Abstract
The present disclosure provides for an exemplary energy storage device and methods of forming thereof, comprising an exemplary conductive graphene ink on exemplary substrates to form durable, flexible, and facile graphene films and energy storage devices for use with and within a variety of electronics and devices.
Claims
1. A conductive graphene ink comprising: a) 20% to about 70% by mass of a binder solution comprising a binder and a first solvent; and b) a reduced graphene oxide dispersion comprising reduced graphene oxide, and a second solvent; wherein the conductive graphene ink has a viscosity of at least about 1,000 centipoise.
2. The conductive graphene ink of claim 1, wherein at least one of the first solvent and the second solvent comprises water, ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof.
3. The conductive graphene ink of claim 1, wherein the binder comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof.
4. The conductive graphene ink of claim 1, wherein the conductive graphene ink has a viscosity of at most about 10,000 centipoise.
5. The conductive graphene ink of claim 1, wherein the conductive graphene ink has a C:O mass ratio of about 2:1 to about 40:1.
6. A method of forming a conductive graphene ink comprising: forming a binder solution comprising: heating a first solvent; adding a binder to the first solvent; mixing the binder and the first solvent; and cooling the binder and the first solvent; forming a reduced graphene oxide dispersion comprising a second solvent and reduced graphene oxide; forming a graphene solution comprising the binder solution and the reduced graphene oxide dispersion; and mixing the graphene solution under a vacuum degree of about −0.05 MPa to about −0.2 MPa to form a conductive graphene ink.
7. The method of claim 6, wherein at least one of the first solvent and the second solvent comprises water, ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof.
8. The method of claim 6, wherein the binder comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof.
9. The method of claim 6, wherein the first solvent is heated to a temperature of about 35° C. to about 125° C.
10. The method of claim 6, wherein the binder is added to the first solvent during the mixing of the binder and the first solvent, over a period of time of about 45 minutes to about 240 minutes.
11. The method of claim 6, wherein, after the binder is fully added to the first solvent, the binder and the first solvent are mixed for a period of time of about 7 minutes to about 30 minutes.
12. The method of claim 6, wherein the mixing of the graphene solution is performed with at least one of a stirring speed of about 15 rpm to about 125 rpm, and a dispersing speed of about 50 rpm to about 4,500 rpm.
13. The method of claim 6, wherein the graphene solution is mixed during one or more intervals, wherein each interval comprises a period of time of about 0.5 minutes to about 30 minutes.
14. The method of claim 6, wherein the binder and the first solvent are cooled to a temperature of about 10° C. to about 40° C.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Features of the disclosure are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the embodiments are utilized, and the accompanying drawings or figures (also “FIG.” and “FIGS.” herein), of which:
(2) FIG. 1 shows an illustration of the composition of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(3) FIG. 2A shows an exemplary schematic illustration of chains of carbon black interconnected through a conductive graphene sheet, in accordance with some embodiments of the present disclosure.
(4) FIG. 2B shows an exemplary schematic illustration of a binder stabilizing the graphene ink, in accordance with some embodiments of the present disclosure.
(5) FIG. 2C shows an exemplary schematic illustration of the chemical interactions between binder and the components of the graphene ink, in accordance with some embodiments of the present disclosure.
(6) FIG. 3A shows an exemplary image of a carbon particle comprising carbon black, in accordance with some embodiments of the present disclosure.
(7) FIG. 3B shows an exemplary transmission electron microscopy (TEM) image of a commercially available form of carbon black, in accordance with some embodiments of the present disclosure.
(8) FIG. 3C shows an exemplary TEM image of a second commercially available form of carbon black, in accordance with some embodiments of the present disclosure.
(9) FIG. 3D shows an exemplary TEM image of a third commercially available form of carbon black, in accordance with some embodiments of the present disclosure.
(10) FIG. 4 shows an exemplary image of raw graphene, in accordance with some embodiments transmission electron microscopy, which is used to make the graphene sheet 101.
(11) FIG. 5A shows an image of an exemplary conductive graphene ink being removed from a mixer, in accordance with some embodiments of the present disclosure.
(12) FIG. 5B shows an image of an exemplary conductive graphene ink being poured into a beaker, in accordance with some embodiments of the present disclosure.
(13) FIG. 5C shows an image of an exemplary conductive graphene ink in a jar, in accordance with some embodiments of the present disclosure.
(14) FIG. 6A shows a first optical microscopy image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(15) FIG. 6B shows a second optical microscopy image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(16) FIG. 7A shows a first high-magnification scanning electron microscopy (SEM) image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(17) FIG. 7B shows a second high-magnification SEM image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(18) FIG. 7C shows a third high-magnification SEM image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(19) FIG. 7D shows a fourth high-magnification SEM image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(20) FIG. 8 shows an image of an exemplary apparatus for forming a conductive graphene ink, in accordance with some embodiments of the present disclosure.
(21) FIG. 9 shows a particle size distribution chart of an exemplary conductive graphene ink.
(22) FIG. 10 shows a Raman spectra chart of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(23) FIG. 11 shows an X-ray diffraction chart of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(24) FIG. 12A shows an image of an exemplary conductive graphene ink on an exemplary substrate, in accordance with some embodiments of the present disclosure.
(25) FIG. 12B shows an image of an exemplary roll of a conductive graphene ink-coated substrate, in accordance with some embodiments of the present disclosure.
(26) FIG. 13 shows an image of an exemplary graphene film comprising a conductive graphene logo on an exemplary substrate, in accordance with some embodiments of the present disclosure.
(27) FIG. 14A shows an image of an exemplary graphene films comprising arrays of two interdigitated electrodes formed from an exemplary conductive graphene ink and an exemplary substrate, in accordance with some embodiments of the present disclosure.
(28) FIG. 14B shows an image of an exemplary graphene films comprising arrays of three interdigitated electrodes formed from an exemplary conductive graphene ink and an exemplary substrate, in accordance with some embodiments of the present disclosure.
(29) FIG. 15A shows an image of an exemplary radio frequency identification device printed on an exemplary conductive graphene ink on an exemplary paper substrate, in accordance with some embodiments of the present disclosure.
(30) FIG. 15B shows an image of an exemplary radio frequency identification device printed on an exemplary conductive graphene ink on an exemplary paper substrate, in accordance with some embodiments of the present disclosure.
(31) FIG. 16 shows a schematic illustration of an exemplary method of forming a graphene film, in accordance with some embodiments of the present disclosure.
(32) FIG. 17 shows an image of an exemplary method of forming a graphene film with a brush, in accordance with some embodiments of the present disclosure.
(33) FIG. 18 shows an illustration of an exemplary method of forming a graphene film with a doctor blade, in accordance with some embodiments of the present disclosure.
(34) FIG. 19A shows an image of an exemplary doctor blade apparatus, in accordance with some embodiments of the present disclosure.
(35) FIG. 19B shows an image of an exemplary graphene film formed with a doctor blade, in accordance with some embodiments of the present disclosure.
(36) FIG. 20 shows an image of an exemplary method of coating a substrate with graphene ink with a screen printer, in accordance with some embodiments of the present disclosure.
(37) FIG. 21A shows an image of an exemplary substrate in a roll-to-roll printer, in accordance with some embodiments of the present disclosure.
(38) FIG. 21B shows an image of an exemplary graphene ink coating an exemplary substrate in a roll-to-roll printer, in accordance with some embodiments of the present disclosure.
(39) FIG. 21C shows an image of an exemplary graphene film formed by a roll-to-roll printer, in accordance with some embodiments of the present disclosure.
(40) FIG. 22 shows a plot of the sheet resistance and dry thickness of an exemplary conducting graphene coating, in accordance with some embodiments of the present disclosure.
(41) FIG. 23 shows an current-voltage plot of an exemplary conducting graphene coating, in accordance with some embodiments of the present disclosure.
(42) FIG. 24A shows a graph of the sheet resistance of exemplary conducting graphene-coated substrates with a dry coating thickness of 41 micrometers, in accordance with some embodiments of the present disclosure.
(43) FIG. 24B shows a graph of the sheet resistance of exemplary conducting graphene-coated substrates with a wet coating thickness of 200 micrometers, in accordance with some embodiments of the present disclosure.
(44) FIG. 25 shows an exemplary apparatus for testing the resistance of a conductive graphene ink coated on a substrate, in accordance with some embodiments of the present disclosure.
(45) FIG. 26A shows a plot of the bend radius and the resistance change of an exemplary graphene-coated substrate under convex bending, in accordance with some embodiments of the present disclosure.
(46) FIG. 26B shows an illustration of the convex bending radius of an exemplary graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(47) FIG. 26C shows a plot of the bend radius and the resistance change of an exemplary graphene-coated substrate under concave bending, in accordance with some embodiments of the present disclosure.
(48) FIG. 26D shows an illustration of the concave bending radius of an exemplary graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(49) FIG. 27A shows a graph of the resistance change of exemplary flat, bent, and twisted graphene-coated substrates, in accordance with some embodiments of the present disclosure.
(50) FIG. 27B shows an image of an exemplary flat graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(51) FIG. 27C shows an image of an exemplary bent graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(52) FIG. 27D shows an exemplary image of a first exemplary twisted graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(53) FIG. 27E shows an image of a second exemplary twisted graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(54) FIG. 28 shows a plot of the bend cycles at a radius of about 10 mm and the resistance change of an exemplary graphene-coated substrate, in accordance with some embodiments of the present disclosure.
(55) FIG. 29A is an illustration of a conductive graphene ink comprising silver nanoparticles below percolation, in accordance with some embodiments of the present disclosure.
(56) FIG. 29B is an illustration of a conductive graphene ink comprising silver nanoparticles with a percolation threshold of about 15%, in accordance with some embodiments of the present disclosure.
(57) FIG. 29C is an illustration of a conductive graphene ink comprising silver nanoparticles with a percolation threshold of less than 1%, in accordance with some embodiments of the present disclosure.
(58) FIG. 30 shows TEM images of exemplary silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel, in accordance with some embodiments of the present disclosure.
(59) FIG. 31A displays an exemplary solution comprising silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel, in accordance with some embodiments of the present disclosure.
(60) FIG. 31B displays the exemplary solution of FIG. 31A after resting for about one week, in accordance with some embodiments of the present disclosure.
(61) FIG. 32 shows TEM images of exemplary silver nanowires formed by injecting the silver-based solution into the reaction vessel over a period of time of about 15 minutes, in accordance with some embodiments of the present disclosure.
(62) FIG. 33A displays an exemplary solution comprising silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel, in accordance with some embodiments of the present disclosure.
(63) FIG. 33B displays the exemplary solution of FIG. 33A after resting for about one week, in accordance with some embodiments of the present disclosure.
(64) FIG. 34 shows TEM images of exemplary silver nanowires formed with a high viscosity binder, in accordance with some embodiments of the present disclosure.
(65) FIG. 35 shows an image of an exemplary conductive silver-based ink comprising silver nanowires formed with a high viscosity binder, in accordance with some embodiments of the present disclosure.
(66) FIG. 36 shows optical microscope images of an exemplary film comprising silver nanowires formed by a solvothermal method, in accordance with some embodiments of the present disclosure.
(67) FIG. 37 shows an image of an exemplary conductive silver-based ink comprising silver nanowires formed with a high viscosity binder, in accordance with some embodiments of the present disclosure.
(68) FIG. 38 shows an image of an exemplary apparatus for forming silver nanowires formed by a solvothermal method, in accordance with some embodiments of the present disclosure.
(69) FIG. 39 shows TEM images of exemplary silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments of the present disclosure.
(70) FIG. 40A shows an image of an exemplary conductive silver-based ink during seeding and nucleation of the silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments of the present disclosure.
(71) FIG. 40B shows an image of an exemplary conductive silver-based ink during growth of the silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments of the present disclosure.
(72) FIG. 41A shows a TEM image of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure.
(73) FIG. 41B shows another TEM image of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure.
(74) FIG. 41C shows another TEM image of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure.
(75) FIG. 41D shows another TEM image of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure.
(76) FIG. 41E shows another TEM image of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure.
(77) FIG. 41F shows another TEM image of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure.
(78) FIG. 42A shows an image of an exemplary conductive additive comprising silver nanowires before nucleation, in accordance with some embodiments of the present disclosure.
(79) FIG. 42B shows an image of an exemplary conductive additive comprising silver nanowires at nucleation initiation, in accordance with some embodiments of the present disclosure.
(80) FIG. 42C shows an image of an exemplary conductive additive comprising silver nanowires during nucleation, in accordance with some embodiments of the present disclosure.
(81) FIG. 42D shows an image of an exemplary conductive additive during silver nanowire growth, in accordance with some embodiments of the present disclosure.
(82) FIG. 43A shows a front image of an exemplary apparatus for forming a conductive additive comprising silver nanowires, in accordance with some embodiments of the present disclosure.
(83) FIG. 43B shows a perspective image of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure.
(84) FIG. 43C shows a detailed front image of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure.
(85) FIG. 43D shows a detailed perspective image of an exemplary bath and reaction chamber of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure.
(86) FIG. 43E shows a highly detailed front image of an exemplary bath and reaction chamber of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure.
(87) FIG. 43F shows a highly detailed perspective image of an exemplary bath and reaction chamber of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure.
(88) FIG. 44 shows a TEM image of exemplary silver nanoparticles formed by a first method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure.
(89) FIG. 45A shows a first image of an exemplary dispersion of silver nanoparticles formed by a first method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure.
(90) FIG. 45B shows a second image of an exemplary dispersion of silver nanoparticles formed by a first method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure.
(91) FIG. 46A shows an image of an exemplary first solution of silver nanoparticles heated to 100° C., in accordance with some embodiments of the present disclosure.
(92) FIG. 46B shows an image of an exemplary first solution of silver nanoparticles heated to 110° C., in accordance with some embodiments of the present disclosure.
(93) FIG. 46C shows an image of an exemplary first solution of silver nanoparticles heated to 120° C., in accordance with some embodiments of the present disclosure.
(94) FIG. 46D shows an image of an exemplary first solution of silver nanoparticles heated to 130° C., in accordance with some embodiments of the present disclosure.
(95) FIG. 46E shows an image of an exemplary first solution of silver nanoparticles heated to 145° C., in accordance with some embodiments of the present disclosure.
(96) FIG. 46F shows an image of an exemplary first solution of silver nanoparticles heated to 160° C., in accordance with some embodiments of the present disclosure.
(97) FIG. 47 shows a TEM image of exemplary silver nanoparticles formed by a second method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure.
(98) FIG. 48 shows an current-voltage curve of an exemplary film comprising an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
DETAILED DESCRIPTION
(99) Provided herein are graphene materials, fabrication processes, and devices with improved performance. Optionally, in some embodiments, the present disclosure provides devices and methods for forming a conductive graphene ink comprising a graphene material and devices and methods for forming a conductive graphene film comprising a substrate coated with a conductive ink comprising a graphene material. Such graphene inks and films avoid the shortcomings of conductive inks. The conductive graphene ink can be used to form patterns and shapes comprising electrodes and wires on a substrate.
(100) Various aspects of the disclosure described herein may be applied to any of the particular applications set forth below or in any other type of manufacturing, synthesis, or processing setting. Other manufacturing, synthesis, or processing of materials may equally benefit from features described herein. For example, the methods, devices, and systems herein may be advantageously applied to manufacture (or synthesis) of various forms of graphene or graphene oxide. The embodiments described herein may be applied as a stand-alone method, device, or system or as part of an integrated manufacturing or materials (e.g., chemicals) processing system. It shall be understood that different aspects of the disclosure may be appreciated individually, collectively, or in combination with each other.
(101) Reference will now be made to the figures. It will be appreciated that the figures and features therein are not necessarily drawn to scale. The schematic illustrations, images, formulas, charts, and graphs referred to herein represent fabricated exemplary devices that serve as a representation of the appearance, characteristics, and functionality of the devices produced by the exemplary methods described herein.
(102) While preferable embodiments have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art. It should be understood that various alternatives to the embodiments described herein may be employed.
(103) Provided herein per FIGS. 1 to 7D are conductive graphene inks and components for the fabrication of the conductive inks thereof. FIG. 1 shows an illustration of the composition of an exemplary conductive graphene ink, in accordance with some embodiments. Per FIG. 1, the exemplary conductive graphene ink 100 comprises a graphene sheet 101, a carbon particle 102, a binder 103, a surfactant 104, a defoamer 105, and a first solvent 106.
(104) FIGS. 2A-2C show exemplary schematic illustrations of the chemical bonds within a conductive graphene ink, in accordance with some embodiments. FIG. 2A shows an exemplary schematic illustration of chains of carbon black interconnected through a conductive graphene sheet, in accordance with some embodiments of the present disclosure. Per FIG. 2A, although interconnected carbon particle chains 204 of carbon particles 202 within graphene inks are capable of conducting an electrical current, the isolation of the carbon particle chains 204 must be overcome to enable continuous conductivity within graphene inks 200. However, embedding the carbon particle chains 204 within conductive graphene sheets 201 through van der Waals forces forms a continuous conductive graphene ink 200.
(105) FIG. 2B shows an exemplary schematic illustration of a binder stabilizing the graphene ink, in accordance with some embodiments. FIG. 2C shows an exemplary schematic illustration of the chemical interactions between binder and the components of the graphene ink, in accordance with some embodiments. Per FIGS. 2A to 2C, the conductive graphene ink optionally further comprises a binder 203, wherein the a negatively charged backbone of the binder 203 forms stable emulsions within, and further increases the conductivity of, the conductive graphene ink. Optionally, in some embodiments, the binder 203 comprises a polymer. Optionally, in some embodiments, the polymer comprises a synthetic polymer. Optionally, in some embodiments, the synthetic polymer comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof. Optionally, in some embodiments, the binder is incorporated into the conductive graphene ink via a binder solution. Carboxymethyl cellulose, an exemplary polymer binder, forms extensive hydrogen bonding with both carbon particles 202 and graphene sheets 201, thus increases the stability of the conductive graphene ink. Furthermore, the use of a binder increases the adhesion of the components within the conductive graphene ink, the adhesion of the conductive graphene ink to a substrate, and the flexibility of the graphene film produced therewith. Per FIGS. 2B and 2C, the conductive graphene ink optionally further comprises a solvent. Some forms of carbon particles 202, such as carbon black, contains surface functional groups comprising, for example, —H, —OH, —CO, —COOH, which render its surface hydrophilic to increase its interaction with solvents and the graphene sheets 201.
(106) FIG. 3A shows an exemplary image of a carbon particle 202 comprising carbon black, in accordance with some embodiments of the present disclosure. FIG. 3B shows an exemplary transmission electron microscopy (TEM) image of a commercially available form of carbon black, in accordance with some embodiments of the present disclosure. FIG. 3C shows an exemplary TEM image of a second commercially available form of carbon black, in accordance with some embodiments of the present disclosure. FIG. 3D shows an exemplary TEM image of a third commercially available form of carbon black, in accordance with some embodiments of the present disclosure. Carbon black is a material typically produced by the incomplete combustion of heavy petroleum products such as fluid catalytic cracking tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. As seen in FIGS. 3B-3D, carbon black is a form of paracrystalline carbon that typically has a high surface area-to-volume ratio. Forms of carbon black include but are not limited to Super C45, Super C65, and Super P.
(107) FIG. 4 shows an exemplary image of raw graphene, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, raw graphene is used to make the graphene sheet.
(108) FIGS. 5A-5C show images of an exemplary conductive graphene ink in accordance with some embodiments of the present disclosure. FIG. 5A shows an image of an exemplary conductive graphene ink being removed from a mixer, in accordance with some embodiments of the present disclosure. FIG. 5B shows an image of an exemplary conductive graphene ink being poured into a beaker, in accordance with some embodiments of the present disclosure. FIG. 5C shows an image of an exemplary conductive graphene ink in a jar, in accordance with some embodiments of the present disclosure. As seen in FIGS. 5A-5C, the conductive graphene ink is highly viscous. As shown, the conductive graphene ink is black. Optionally, in some embodiments, the conductive graphene ink is blue, green, red, yellow, orange, indigo, violet, or any combination thereof.
(109) FIG. 6A shows a first optical microscopy image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. FIG. 6B shows a second optical microscopy image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. FIG. 7A shows a first high-magnification scanning electron microscopy (SEM) image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. FIG. 7B shows a second high-magnification SEM image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. FIG. 7C shows a third high-magnification SEM image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. FIG. 7D shows a fourth high-magnification SEM image of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure.
(110) Optionally, in some embodiments, the conductive graphene ink has a viscosity of at most about 10,000 centipoise. Optionally, in some embodiments, the conductive graphene ink has a surface area of at least about 40 m.sup.2/g. Optionally, in some embodiments, the graphene ink has a resistivity when dry of about 0.01 ohm/sq/mil to about 60 ohms/sq/mil.
(111) Provided herein is a method of forming a conductive graphene ink comprising: forming a binder solution; forming a reduced graphene oxide dispersion; and forming a graphene solution comprising the binder solution, the reduced graphene dispersion, a third solvent, a conductive additive, a surfactant, and a defoamer; and mixing the graphene solution to form a conductive graphene ink. Optionally, in some embodiments, forming a binder solution comprises heating a first solvent, adding a binder to the first solvent, mixing the binder and the first solvent, and cooling the binder and the first solvent. Optionally, in some embodiments, the reduced graphene oxide dispersion comprises a second solvent and reduced graphene oxide.
(112) FIG. 8 shows an image of an exemplary apparatus for forming a conductive graphene ink, in accordance with some embodiments of the present disclosure. Per FIG. 8, the exemplary apparatus for mixing a binder of a conductive graphene ink comprises a first mechanical mixer 801, a beater 802, and a hot plate 803.
(113) Optionally, in some embodiments, the process of forming a binder solution comprises: heating a first solvent 810, adding a binder 812 to the first solvent 810, mixing the binder 812 and the first solvent 810, and cooling the binder 812 and the first solvent 810.
(114) Optionally, in some embodiments, at least one of the first solvent, the second solvent, and the third solvent comprises water, an organic solvent, or any combination thereof. Optionally, in some embodiments, at least one of the first solvent, the second solvent, and the third solvent comprises water and an organic solvent. Optionally, in some embodiments, the organic solvent comprises ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof. Optionally, in some embodiments, at least one of the first solvent, the second solvent, and the third solvent comprises water, ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof.
(115) Optionally, in some embodiments, the binder comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof.
(116) Optionally, in some embodiments, the conductive additive comprises a carbon-based material. Optionally, in some embodiments, the carbon-based material comprises a paracrystalline carbon. Optionally, in some embodiments, the paracrystalline carbon comprises carbon black, acetylene black, channel black, furnace black, lamp black, thermal black, or any combination thereof. Optionally, in some embodiments, the conductive additive comprises silver. Optionally, in some embodiments, the silver comprises silver nanoparticles, silver nanorods, silver nanowires, silver nanoflowers, silver nanofibers, silver nanoplatelets, silver nanoribbons, silver nanocubes, silver bipyramids, or any combination thereof.
(117) Optionally, in some embodiments, the surfactant comprises perfluorooctanoic acid, perfluorooctane sulfonate, perfluorohexane sulfonic acid, perfluorononanoic acid, perfluorodecanoic acid, polyethylene glycol alkyl ethers, octaethylene glycol monododecyl ether, pentaethylene glycol monododecyl ether, polypropylene glycol alkyl ethers, glucoside alkyl ethers, decyl glucoside, lauryl glucoside, octyl glucoside, polyethylene glycol octylphenyl ethers, Triton X-100, polyethylene glycol alkylphenyl ethers, nonoxynol-9, glycerol alkyl esters polysorbate, sorbitan alkyl esters poloxamers, polyethoxylated tallow amine, Dynol 604, or any combination thereof.
(118) Optionally, in some embodiments, the defoamer comprises an insoluble oil, a silicone, a glycol, a stearate, an organic solvent, Surfynol DF-1100, alkyl polyacrylate, or any combination thereof. Optionally, in some embodiments, the insoluble oil comprises mineral oil, vegetable oil, white oil, or any combination thereof. Optionally, in some embodiments, the silicone comprises polydimethylsiloxane, silicone glycol, a fluorosilicone, or any combination thereof. Optionally, in some embodiments, the glycol comprises polyethylene glycol, ethylene glycol, propylene glycol, or any combination thereof. Optionally, in some embodiments, the stearate comprises glycol stearate, stearin, or any combination thereof. Optionally, in some embodiments, the organic solvent comprises ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof.
(119) High quantities of water in water-based conductive graphene inks may optionally increase the surface tension of the ink. In some applications, such as in inkjet printing, however, a low, controlled surface tension and viscosity is required to maintain consistent jetting through the print head nozzles. The addition of a surfactant may reduce the surface tension of an ink because as the surfactant units move to the water/air interface, their relative force of attraction weakens as the non-polar surfactant heads become exposed.
(120) A specific ink viscosity is important for some applications. For example, a viscosity of greater than about 1000 mPa.Math.s is ideal for ink for screen printing, wherein a viscosity lower than 20 mPa.Math.s works best for inkjet printing. Optionally, in some embodiments, the viscosity of the conductive graphene ink can be controlled by the amount of at least one of the first solvent, the second solvent, the third solvent, and binder used, wherein lower quantities of at least one of the first solvent, the second solvent, and the third solvent form inks with lower viscosities.
(121) Optionally, in some embodiments, the mixing of the binder and the first solvent is performed by a first mechanical mixer. Optionally, in some embodiments, the mixing of the binder solution, the first solvent, the conductive additive, and the RGO dispersion is performed by a second mechanical mixer. Optionally, in some embodiments, the second mechanical mixer mixes the graphene solution at a stirring speed of about 15 rpm to about 125 rpm. Optionally, in some embodiments, the second mechanical mixer mixes the graphene solution during one or more intervals, wherein each interval comprises a period of time of about 0.5 minute to about 30 minutes. Optionally, in some embodiments, the second mechanical mixer mixes the graphene solution under a vacuum degree, and wherein the vacuum degree is equal to the ambient pressure. Optionally, in some embodiments, the second mechanical mixer mixes the graphene solution under a vacuum degree, and wherein the vacuum degree is about −0.05 MPa to about −0.2 MPa.
(122) Optionally, in some embodiments, the method of forming the binder dictates the mechanical and electrical performance characteristics of the conductive graphene ink and the graphene films formed thereby. Optionally, in some embodiments, the method herein is capable of producing a conductive graphene ink capable of forming a thin consistent layer with a low lateral thickness, when coated on a substrate.
(123) FIG. 9 shows a particle size distribution chart of an exemplary conductive graphene ink. Optionally, in some embodiments, the particle size distribution of the conductive graphene ink, per FIG. 9, was determined by measuring the static light scattering of a dilute solution of homogeneously disbursed conductive graphene ink. As seen in FIG. 9, the exemplary conductive graphene ink comprises particles ranging from about 1 μm to about 50 μm, wherein the most prevalent particle size is about 2 μm.
(124) FIG. 10 shows a Raman spectra chart of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the Raman spectra of the conductive graphene ink, per FIG. 10, were obtained with a 633 nm laser with a 10 second acquisition time on samples of conductive graphene ink that were drop-cast onto a silicon wafer.
(125) FIG. 11 shows an X-ray diffraction chart of an exemplary conductive graphene ink, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the X-ray diffraction graphs of the conductive graphene ink, per FIG. 11, were obtained by measuring the spectra of a purified graphene oxide that is drop-cast onto a zero-background silicon over a 15 minute scan from a 2theta of 0 to 40 degrees.
(126) FIGS. 12A-14B show images of exemplary graphene films comprising conductive graphene ink on a substrate. FIG. 12A shows an image of an exemplary conductive graphene ink on an exemplary substrate, in accordance with some embodiments of the present disclosure. FIG. 12B shows an image of an exemplary roll of a conductive graphene ink coated substrate, in accordance with some embodiments of the present disclosure. Per FIGS. 12A and 12B, the graphene films 1200 comprise a conductive graphene ink 1202 covering a majority of the exemplary substrate 1201. Optionally, in some embodiments, the substrate 1201 comprises metal, plastic, paper, wood, silicon, metal, glass, fiberglass, carbon fiber, ceramics, fabric, or any combination thereof. Optionally, in some embodiments, the conductive graphene ink 1202 covers at least a portion of the substrate 1201. Optionally, in some embodiments, the conductive graphene ink 1202 covers the entirety of the substrate 1201. Optionally, in some embodiments, the graphene film 1200 comprises a conductive graphene ink 1202 covering a majority of the substrate 1201 wherein a portion of the substrate 1201 not covered by the conductive graphene ink 1202 is removed. Optionally, in some embodiments, the graphene film 1200 can be cut to form graphene film 1200 ribbons, particles, shapes, cutouts, wires, connectors, or any combination thereof.
(127) FIG. 13 shows an image of an exemplary graphene film comprising a conductive graphene logo on an exemplary substrate, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the graphene film 1200 comprises a conductive graphene ink 1202 that is screen-printed to form a logo on an exemplary substrate 1201. Optionally, in some embodiments, the printing resolution of the conductive graphene ink 1202 on an exemplary substrate 1201 is defined, and only limited by, the resolution of the printer used to deposit the conductive graphene ink 1202. Optionally, in some embodiments, the substrate 1201 comprises metal, wood, glass, paper, an organic material, cloths, plastics, fiberglass, carbon cloth, carbon fiber, silicon, or any combination thereof.
(128) FIGS. 14A and 14B shows images of an exemplary graphene films comprising arrays of interdigitated electrodes formed from an exemplary conductive graphene ink and an exemplary substrate, in accordance with some embodiments. FIG. 14A shows an image of an exemplary graphene films comprising arrays of two interdigitated electrodes formed from an exemplary conductive graphene ink and an exemplary substrate, in accordance with some embodiments of the present disclosure. FIG. 14B shows an image of an exemplary graphene films comprising arrays of three interdigitated electrodes formed from an exemplary conductive graphene ink and an exemplary substrate, in accordance with some embodiments of the present disclosure. As shown, the exemplary graphene film 1200 comprises interdigitated electrodes 1401a, 1401b formed from the conductive graphene ink 1202 and the substrate 1201 and comprising two and four electrodes, respectively. Optionally, in some embodiments, the exemplary graphene film 1200 comprises interdigitated electrodes 1401a, 1401b comprising two, three, four, five, six, seven, eight, or more electrodes. Optionally, in some embodiments, the number of interdigitated electrodes 1401a, 1401b formed by the conductive graphene ink 1202 on an exemplary substrate 1201 is defined, and only limited by, the resolution of the printer used to deposit the conductive graphene ink 1202. Per FIGS. 14A and 14B, the exemplary graphene film 1200 comprises an array of interdigitated electrodes 1401a, 1401b, wherein one or more of the interdigitated electrodes 1401a, 1401b within the exemplary graphene film 1200 may be separated and used individually.
(129) FIG. 15A shows an image of an exemplary graphene film comprising arrays of radio frequency identification (RFID) chips formed from an exemplary conductive graphene ink and an exemplary substrate, in accordance with some embodiments. An array of exemplary non-limiting RFID chips 1501 comprises an exemplary substrate 1201 coated with an exemplary conductive graphene ink 1202 is shown in FIG. 15A. Optionally, in some embodiments, the number of interdigitated electrodes 1401a, 1401b formed by the conductive graphene ink 1202 on an exemplary substrate 1201 is defined, and only limited by, the resolution of the printer used to deposit the conductive graphene ink 1202. Per FIGS. 14A and 14B, the exemplary graphene film 1200 comprises an array of interdigitated electrodes 1401a, 1401b, wherein one or more of the interdigitated electrodes 1401a, 1401b within the exemplary graphene film 1200 may be separated and used individually.
(130) FIG. 15B shows an image of an exemplary RFID device printed on an exemplary conductive graphene ink on an exemplary paper substrate, in accordance with some embodiments of the present disclosure. An exemplary non-limiting RFID chip 1501 is shown in FIG. 15 wherein the exemplary conductive graphene ink 1202 is coated on an exemplary substrate 1201, wherein the substrate 1201 comprises paper.
(131) FIG. 16 shows a schematic illustration of an exemplary method of forming a graphene film, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the method of forming a graphene film 1600 comprises coating a substrate 1601 with a conductive graphene ink 1602, and drying 1603 the conductive graphene ink 1602 on the substrate 1601. Optionally, in some embodiments, drying 1603 the conductive graphene ink 1602 on the substrate 1601 forms a graphene coating 1604 comprising a highly porous array of graphene sheets 1605. Optionally, in some embodiments, the method of forming a graphene film 1600 further comprises compressing 1606 the graphene coating 1604 to form a compressed laminate 1607. Optionally, in some embodiments, the compressed laminate 1607 comprises a highly dense array of graphene sheets 1608.
(132) FIG. 17 shows an image of an exemplary method of forming a graphene film with a brush, in accordance with some embodiments. As seen in FIG. 17, an exemplary graphene ink 1602 is applied by a brush. Additionally, an exemplary substrate 1601, comprising paper, is shown in FIG. 17. Alternatively, the exemplary graphene ink 1602 is applied by a roller, a pipette, a pen, or any other known method of applying a liquid to a substrate. Optionally, in some embodiments, the ability of the exemplary graphene ink 1602 to be safely and easily applied to a substrate 1601 enables its use in such applications as prototyping, educational demonstrations, and learning activities.
(133) FIGS. 18 to 19B display an exemplary method of forming a graphene film with a doctor blade. FIG. 18 shows an illustration of an exemplary method of forming a graphene film with a doctor blade, in accordance with some embodiments of the present disclosure. FIG. 19A shows an image of an exemplary doctor blade apparatus, in accordance with some embodiments of the present disclosure. FIG. 19B shows an image of an exemplary graphene film formed with a doctor blade, in accordance with some embodiments of the present disclosure.
(134) An exemplary method of forming a graphene film with a doctor blade, per FIG. 18, comprises depositing graphene ink 1602 onto a substrate 1601 and translating a doctor blade 1800 from one end to another end of the a substrate 1601 to form a coating of the graphene ink 1602 with a consistent thickness. As seen in FIGS. 19A and 19B, the doctor blade 1800 is configured to produce a graphene film with a consistent thickness. Optionally, in some embodiments, the doctor blade 1800 can be adjusted to spread a certain thickness of the graphene ink 1602 onto a substrate 1601. Optionally, in some embodiments, the thickness of the graphene ink 1602 affects the electrical properties of the graphene film. Optionally, in some embodiments, the doctor blade 1800 applies the graphene ink 1602 onto the entirety of the substrate 1601.
(135) FIG. 20 shows an image of an exemplary method of coating a substrate with graphene ink with a screen printer, in accordance with some embodiments of the present disclosure. Per FIG. 20, the exemplary method of forming a graphene film with a screen printer comprises depositing a screen onto a substrate, depositing graphene ink onto the screen and translating a squeegee from one end to another end of the a substrate to form a coating of the graphene ink with a consistent thickness. Optionally, in some embodiments, the screen comprises a stencil that is impermeable to the ink. Optionally, in some embodiments, screen printing is configured to produce a graphene film with a consistent thickness. Optionally, in some embodiments, the screen printer is adjusted to spread a certain thickness of the graphene ink onto a substrate. Optionally, in some embodiments, the screen printer applies the graphene ink onto the entirety of the substrate or one or more portions of the substrate.
(136) FIGS. 21A-21C show images of an exemplary method of coating a substrate with graphene ink with a roll-to-roll printer, in accordance with some embodiments of the present disclosure. FIG. 21A shows an image of an exemplary substrate in a roll-to-roll printer, in accordance with some embodiments of the present disclosure. FIG. 21B shows an image of an exemplary graphene ink coating an exemplary substrate in a roll-to-roll printer, in accordance with some embodiments of the present disclosure. FIG. 21C shows an image of an exemplary graphene film formed by a roll-to-roll printer, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, roll-to-roll printing is configured to produce a graphene film with a consistent thickness. Optionally, in some embodiments, the roll-to-roll printer is adjusted to spread a certain thickness of the graphene ink onto a substrate. Optionally, in some embodiments, the roll-to-roll printer applies the graphene ink onto the entirety of the substrate, or one or more portions of the substrate.
(137) Alternatively, in this or any other embodiment, any other method or combination of methods known to those of skill in the art can be used to apply the graphene ink to a substrate to form a graphene film.
(138) FIGS. 22-25 show the performance of exemplary graphene films. FIG. 22 shows a plot of the sheet resistance and dry thickness of an exemplary conducting graphene coating, in accordance with some embodiments of the present disclosure. Per FIG. 22, the sheet resistance of the exemplary non-limiting conducting graphene coating decreases from about 120 ohms/sq as the coating thickness increases from about 7 micrometers to about 41 micrometers. The sheet resistance of a graphene film is generally tuned by adjusting the thickness of the conductive graphene ink that coats the substrate. Optionally, in some embodiments, the graphene film has a resistivity of about 0.01 ohm/sq/mil to about 60 ohms/sq/mil.
(139) FIG. 23 shows an current-voltage (I-V) plot of an exemplary conducting graphene coating, in accordance with some embodiments of the present disclosure. As seen in FIG. 23, the linear I-V curve of an exemplary non-limiting graphene film comprising a substrate and a conductive graphene ink with a 300 micrometer wet coating thickness displays a high conductivity.
(140) FIG. 24A shows a graph of the sheet resistance of exemplary conducting graphene-coated substrates with a dry coating thickness of 41 micrometers, in accordance with some embodiments of the present disclosure. FIG. 24B shows a graph of the sheet resistance of exemplary conducting graphene-coated substrates with a wet coating thickness of 200 micrometers, in accordance with some embodiments of the present disclosure. The sheet resistance measurements in four distinct regions of exemplary conducting graphene-coated substrates, per FIGS. 24A and 24B, are consistent and uniform. As sheet resistance is indicative of sheet thickness, the uniform sheet resistance measurements denote a highly uniform thickness.
(141) FIG. 25 shows an exemplary apparatus for testing the resistance of an exemplary conductive graphene ink-coated substrate, in accordance with some embodiments of the present disclosure. As shown per FIG. 25, the exemplary non-limiting apparatus measures the resistance between the exemplary conductive graphene ink 2502 and the exemplary substrate 2501 by a multimeter 2503.
(142) FIG. 26A shows a plot of the bend radius and the resistance change of an exemplary graphene coated substrate under convex bending, in accordance with some embodiments of the present disclosure. FIG. 26B shows an illustration of the convex bending radius of an exemplary graphene coated substrate, in accordance with some embodiments of the present disclosure. FIG. 26C shows a plot of the bend radius and the resistance change of an exemplary graphene coated substrate under concave bending, in accordance with some embodiments of the present disclosure. FIG. 26D shows an illustration of the concave bending radius of an exemplary graphene coated substrate, in accordance with some embodiments of the present disclosure. While the sheet resistance of the exemplary non-limiting graphene ink 2602-coated substrate 2601 slightly increases at extreme bending radii 2603 of about 1.75 mm, FIGS. 26A and 26C show that the resistance returns to baseline once the radius 2603 is increased, or once the graphene ink 2602-coated substrate 2601 is flattened. This resistance reversibility is indicative that the graphene ink 2602-coated substrate 2601 herein is highly flexible and durable and maintains its performance characteristics under a convex bending force 2604 or a concave bending force 2605.
(143) FIG. 27A shows a graph of the resistance change of exemplary flat, bent, and twisted graphene-coated substrates, in accordance with some embodiments of the present disclosure. FIG. 27B shows an image of an exemplary flat graphene-coated substrate, in accordance with some embodiments of the present disclosure. FIG. 27C shows an image of an exemplary bent graphene-coated substrate, in accordance with some embodiments of the present disclosure. FIG. 27D shows an exemplary image of a first exemplary twisted graphene-coated substrate, in accordance with some embodiments of the present disclosure. FIG. 27E shows an image of a second exemplary twisted graphene-coated substrate, in accordance with some embodiments of the present disclosure. As seen in FIG. 27A, a bent device 2702, a first exemplary twisted device 2703, and a second exemplary twisted device 2704 of FIGS. 27C-27E exhibit 99.6%, 98.7%, and 98.4% of the resistance of an exemplary flat device 2701 of FIG. 27B, respectively. The minor resistance decrease caused by bending and twisting indicates that the graphene-coated substrates herein are highly flexible and durable and maintain their performance characteristics under strain.
(144) FIG. 28 shows a plot of the bend cycles at a radius of about 10 mm and the resistance change of an exemplary graphene-coated substrate, in accordance with some embodiments of the present disclosure. As seen in FIG. 28, cyclical bending for up to about 1,000 cycles shows no discernable resistance decrease, proving that the exemplary conductive graphene ink can be coated onto a variety of rigid or flexible substrates to form high-conductivity rigid or flexible devices.
(145) Disclosed herein, per FIGS. 29A to 41F, are conductive silver-based inks, along with methods and apparatus for synthesis thereof. In some embodiments, the conductive silver-based ink comprises a primary solvent and silver nanowires. In some embodiments, the conductive silver-based ink comprises a primary solvent and silver nanoparticles. In some embodiments, the conductive silver-based ink comprises a primary solvent and silver nanoparticles. In some embodiments, the conductive silver-based ink comprises a primary solvent and silver nanowires.
(146) Silver nanostructures, such as silver nanowires and silver nanoparticles, are optimal conductive elements in the fabrication of electrodes, electronics components, energy storage components, and a wide variety of other applications. Silver demonstrates a high thermal and electrical conductivity, allowing it to form durable electronic components. Additionally, silver exhibits intriguing optical properties that enable its use in transparent electronics, such as for solar cells, touch screens, and flexible displays.
(147) In some embodiments, the conductive silver-based ink comprises a primary solvent, silver nanoparticles, and silver nanowires. In some embodiments, the primary solvent comprises water, ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof.
(148) FIG. 29A is an illustration of a conductive ink comprising silver nanoparticles below percolation, in accordance with some embodiments of the present disclosure. FIG. 29B is an illustration of a conductive ink comprising silver nanoparticles with a percolation threshold of about 15%, in accordance with some embodiments of the present disclosure. FIG. 29C is an illustration of a conductive ink comprising silver nanoparticles with a percolation threshold of less than 1%, in accordance with some embodiments of the present disclosure. Percolation threshold is defined as the percentage of the conductive elements that are not interconnected. A low percolation threshold to enable high interconnectivity allows for greater conductivity. Method parameters, such as the component quantities, the order of operation, time periods, and temperatures herein, are configured to ensure a low percolation threshold of the conductive silver-based ink. As shown in FIGS. 29A-29C, in some embodiments, the conductive silver-based ink comprising silver nanoparticles requires a higher percolation threshold than a conductive ink comprising silver nanowires.
(149) Provided herein are methods for forming silver nanowires and silver nanoparticles wherein the methods are generally characterized as follows: Method A: Rapid mixing of a precursor solutions into the reactor. Method B: Injection of the precursors to the reactor at a controlled rate and temperature to control the kinetics of nanowire formation. Method C: Employing polymers, such as polyethylene glycol 400 medium, and employing a reducing agent to control the viscosity of the reaction medium. Method D: Solvothermal silver nanowire formation with a sealed Teflon-line stainless steel autoclave. Method E: Formation of nanowires with an ionic liquid catalyst. Method F: Controlling kinetics of nucleation and growth of nanowires through temperature control.
(150) One aspect provided herein is a method of forming silver nanowires comprising: heating a secondary solvent; adding a catalyst solution and a polymer solution to the secondary solvent to form a first solution; injecting a silver-based solution into the first solution to form a second solution; centrifuging the second solution; and washing the second solution with a washing solution to extract the silver nanowires. Alternatively, in some embodiments of the present disclosure, the methods herein are configured form at least one of a silver nanoparticle, a silver nanorod, a silver nanoflower, a silver nanofiber, a silver nanoplatelet, a silver nanoribbon, a silver nanocube, or a silver bipyramid. In some embodiments, the silver nanowires are configured to be used in a conductive silver-based ink. Alternatively, in some embodiments, the silver nanowires are configured to be used as a conductive additive in a conductive graphene ink.
(151) Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the catalyst solution by a factor of about 20 to about 700. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the catalyst solution by a factor of at least about 20. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the catalyst solution by a factor of at most about 700. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the polymer solution by a factor of about 1.5 to about 6.5. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the polymer solution by a factor of at least about 1.5. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the polymer solution by a factor of at most about 6.5.
(152) Optionally, in some embodiments, the secondary solvent is heated to a temperature of about 75° C. to about 300° C. Optionally, in some embodiments, the secondary solvent is heated for a period of time of about 30 minutes to about 120 minutes. Optionally, in some embodiments, the secondary solvent is stirred while being heated. Optionally, in some embodiments, the stirring is performed by a magnetic stir bar. Optionally, in some embodiments, the stirring is performed at a rate of about 100 rpm to about 400 rpm.
(153) Optionally, in some embodiments, the secondary solvent comprises a glycol. Optionally, in some embodiments, the glycol comprises ethylene glycol, polyethylene glycol 200, polyethylene glycol 400, propylene glycol, or any combination thereof. Optionally, in some embodiments, the polymer solution comprises a polymer comprising polyvinyl pyrrolidone, sodium dodecyl sulfonate, vitamin B2, poly(vinyl alcohol), dextrin, poly(methyl vinyl ether), or any combination thereof.
(154) Optionally, in some embodiments, the catalyst solution comprises a catalyst comprising (a chloride) CuCl.sub.2, CuCl, NaCl, PtCl.sub.2, AgCl, FeCl.sub.2, FeCl.sub.3, tetrapropylammonium chloride, tetrapropylammonium bromide, or any combination thereof. Optionally, in some embodiments, the catalyst solution has a concentration of about 2 mM to about 8 mM. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the catalyst solution by a factor of about 75 to about 250.
(155) Optionally, in some embodiments, the polymer has a molecular weight of about 10,000 to about 40,000. Optionally, in some embodiments, the polymer solution has a concentration of about 0.075 M to about 0.25 M. Optionally, in some embodiments, the kinetics of silver nanowire formation is controlled by adjusting the viscosity of the reaction medium. Optionally, in some embodiments, employing a polymer solution, such as polyethylene glycol 200 or polyethylene glycol 400, the viscosity of which is 6 times higher than that of ethylene glycol, slows down the growth rate of silver particles to form different nanostructures.
(156) Optionally, in some embodiments, the silver-based solution comprises a silver-based material comprising AgNO.sub.3. Optionally, in some embodiments, the silver-based solution has a concentration of about 0.05 M to about 0.2 M. Optionally, in some embodiments, the volume of the secondary solvent is greater than the volume of the silver-based solution by a factor of about 1.5 to about 6.5. Optionally, in some embodiments, the silver-based solution is injected into the first solution over a period of time of about 1 second to about 900 seconds.
(157) Some embodiments further comprise heating the second solution before the process of centrifuging the second solution. Optionally, in some embodiments, the heating of the second solution occurs over a period of time of about 30 minutes to about 120 minutes. Optionally, in some embodiments, the centrifuging occurs at a speed of about 1,500 rpm to about 6,000 rpm. Optionally, in some embodiments, the centrifuging occurs over a period of time of about 10 minutes to about 40 minutes.
(158) Some embodiments further comprise cooling the second solution before the process of centrifuging the second solution. Optionally, in some embodiments, the second solution is cooled to room temperature. Optionally, in some embodiments, the washing solution comprises ethanol, acetone, water, or any combination thereof.
(159) Optionally, in some embodiments, washing the second solution comprises a plurality of washing cycles comprising about two cycles to about six cycles. Some embodiments further comprise dispersing the silver nanowires in a dispersing solution. Optionally, in some embodiments, the dispersing solution comprises ethanol, acetone, and water, or any combination thereof.
(160) FIG. 30 shows TEM images of exemplary silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel, in accordance with some embodiments of the present disclosure. As seen in FIG. 30, the exemplary silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel comprise both short silver nanowires and silver nanoparticles.
(161) FIGS. 31A and 31B show the stability of a solution of the exemplary silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel. FIG. 31A displays an exemplary solution comprising silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel, in accordance with some embodiments of the present disclosure. FIG. 31B displays the exemplary solution of FIG. 31A after resting for about one week, in accordance with some embodiments of the present disclosure.
(162) FIG. 32 shows TEM images of exemplary silver nanowires formed by injecting the silver-based solution into the reaction vessel over a period of time of about 15 minutes, in accordance with some embodiments of the present disclosure. As seen in FIG. 32, the exemplary silver nanowires formed by injecting the silver-based solution into the reaction vessel over a period of time of about 15 minutes comprise silver nanowires having a diameter and a length of about 15 μm to about 20 μm and about 165 nm to about 260 nm, respectively. Optionally, in some embodiments, the sheet resistance of the silver nanowires formed by injecting the silver-based solution into the reaction vessel over a period of time of about 15 minutes is about 3 ohms/sq to about 16 ohms/sq.
(163) FIGS. 33A-B show the stability of a solution of the exemplary silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel. FIG. 33A displays an exemplary solution comprising silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel, in accordance with some embodiments. FIG. 33B displays the exemplary solution of FIG. 33A after resting for about one week, in accordance with some embodiments.
(164) As seen in FIGS. 31A and 31B and 33A and 33B, the exemplary solution of FIG. 31B is more translucent than the exemplary solution of FIG. 33B, in accordance with some embodiments of the present disclosure. As such, the exemplary silver nanowires formed by injecting the silver-based solution into the reaction vessel over a period of time of about 15 minutes may exhibit more stability than the exemplary silver nanowires formed by immediately injecting the silver-based solution into the reaction vessel. In some cases, increased stability allows the exemplary conductive silver-based ink to be stored for long periods of time, without requiring remixing or reconstitution.
(165) FIG. 34 shows TEM images of exemplary silver nanowires formed with a high viscosity binder, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the high viscosity binder slows the growth rate of the silver nanowires. Optionally, in some embodiments, the high viscosity binder comprises polyethylene glycol 400. It can be seen per FIG. 34 that the exemplary silver nanowires formed with a high viscosity binder may comprise mostly nanoparticles. FIG. 35 shows an image of an exemplary conductive silver-based ink comprising silver nanowires formed with a high viscosity binder, in accordance with some embodiments of the present disclosure.
(166) FIG. 36 shows optical microscope images of an exemplary film comprising silver nanowires formed by a solvothermal method, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the solvothermal method comprises forming a silver nanowire in a sealed system. Optionally, in some embodiments, the solvothermal method comprises forming silver nanowires at a high pressure. Optionally, in some embodiments, the solvothermal method comprises forming silver nanowires away from open air. It can be seen per FIG. 36, that the exemplary silver nanowires formed by a solvothermal method may comprise agglomerated nanoparticles. FIG. 37 shows an image of an exemplary conductive silver-based ink comprising silver nanowires formed with a high viscosity binder, in accordance with some embodiments of the present disclosure. FIG. 38 shows an image of an exemplary apparatus for forming silver nanowires formed by a solvothermal method, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the apparatus for forming silver nanowires formed by a solvothermal method comprises an autoclave. Optionally, in some embodiments, the autoclave comprises a stainless steel autoclave. Optionally, in some embodiments, the autoclave comprises a Teflon lined autoclave. Optionally, in some embodiments, the apparatus herein forms at least one of a silver nanoparticle, a silver nanorod, a silver nanowire, a silver nanoflower, a silver nanofiber, a silver nanoplatelet, a silver nanoribbon, a silver nanocube, a silver bipyramid, or any combination thereof.
(167) Optionally, in some embodiments, the method further comprises adding an ionic liquid catalyst. Optionally, in some embodiments, the ionic liquid catalyst comprises tetrapropylammonium chloride, tetrapropylammonium bromide, or any combination thereof. FIG. 39 shows TEM images of exemplary silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments. It can be seen per FIG. 39 that the exemplary silver nanowires formed by a solvothermal method may comprise nanowires and nanorods. FIGS. 40A and 40B show images of the formation of an exemplary conductive silver-based ink comprising silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments of the present disclosure.
(168) FIG. 40A shows an image of an exemplary conductive silver-based ink during seeding and nucleation of the silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments of the present disclosure. FIG. 40B shows an image of an exemplary conductive silver-based ink during growth of the silver nanowires formed with an ionic liquid catalyst, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the conductive silver-based ink reaches a temperature of about 120° C. during the seeding and nucleation of the silver nanowires. Optionally, in some embodiments, the conductive silver-based ink, per FIG. 40A, displays a light brown color during the seeding and nucleation of the silver nanowires. Optionally, in some embodiments, the conductive silver-based ink reaches a temperature of about 160° C. during the growth of the silver nanowires. Optionally, in some embodiments, the conductive silver-based ink, per FIG. 40B, displays a milky white color during the growth of the silver nanowires.
(169) Optionally, in some embodiments, the viscosity of the conductive silver-based ink comprising an ionic liquid catalyst has a viscosity of about 4 mPa.Math.s at a temperature of about 22.7° C. Optionally, in some embodiments, the viscosity of the conductive silver-based ink comprising an ionic liquid catalyst has a viscosity of about 2 mPa.Math.s to about 8 mPa.Math.s at a temperature of about 22.7° C. The low viscosity of the conductive inks provided herein allow for accurate, precise, and consistent printing.
(170) FIGS. 41A-41F show TEM images of exemplary silver nanowires formed with controlled nucleation and growth, in accordance with some embodiments of the present disclosure. It can be seen per FIGS. 41A-41F that the exemplary silver nanowires formed with controlled nucleation and growth may comprise long and thin nanowires. Optionally, in some embodiments, controlled nucleation and growth comprises controlling the temperature of the conductive solution to about 120° C. during the nucleation of the silver nanowires. Optionally, in some embodiments, controlled nucleation and growth comprises controlling the temperature of the conductive solution to about 160° C. during the growth of the silver nanowires.
(171) Optionally, in some embodiments, the silver nanowires formed with controlled nucleation and growth comprise a width of about 40 nm to about 125 nm. Optionally, in some embodiments, the silver nanowires formed with controlled nucleation and growth comprise a width of about 75 nm. Optionally, in some embodiments, the silver nanowires formed with controlled nucleation and growth comprise a length of about 7 um to about 100 um. Optionally, in some embodiments, the silver nanowires formed with controlled nucleation and growth comprise a length of about 15 μm to about 50 μm. Optionally, in some embodiments, the silver nanowires formed with controlled nucleation and growth comprise an aspect ratio of about 120:1 to about 1250:1. Optionally, in some embodiments, the silver nanowires formed with controlled nucleation and growth comprise an aspect ratio of about 200:1 to about 700:1. Optionally, in some embodiments, further nucleation control yields longer and thinner silver nanowires.
(172) FIGS. 42A-42D show images of the controlled nucleation and growth of an exemplary conductive silver-based ink comprising silver nanowires, in accordance with some embodiments of the present disclosure. FIG. 42A shows an image of an exemplary conductive silver-based ink comprising silver nanowires before nucleation, in accordance with some embodiments of the present disclosure. FIG. 42B shows an image of an exemplary conductive silver-based ink comprising silver nanowires at nucleation initiation, in accordance with some embodiments of the present disclosure. FIG. 42C shows an image of an exemplary conductive silver-based ink comprising silver nanowires during nucleation, in accordance with some embodiments of the present disclosure. FIG. 42D shows an image of an exemplary conductive silver-based ink during silver nanowire growth, in accordance with some embodiments of the present disclosure. It can be seen, per FIGS. 42A-42D, that the exemplary conductive silver-based ink is translucent before nucleation and becomes more opaque, white, and chalky as nucleation initiates and growth of the silver nanowires.
(173) FIGS. 43A-43F show images of an exemplary apparatus for forming a conductive silver-based ink comprising silver nanowires. FIG. 43A shows a front image of an exemplary apparatus for forming a conductive silver-based ink comprising silver nanowires, in accordance with some embodiments of the present disclosure. FIG. 43B shows a perspective image of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure. FIG. 43C shows a detailed front image of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure. FIG. 43D shows a detailed perspective image of an exemplary bath and reaction chamber of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure. FIG. 43E shows a highly detailed front image of an exemplary bath and reaction chamber of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure. FIG. 43F shows a highly detailed perspective image of an exemplary bath and reaction chamber of the exemplary apparatus of FIG. 43A, in accordance with some embodiments of the present disclosure. As seen in FIG. 43A, the exemplary apparatus for forming a conductive silver-based ink comprising silver nanowires comprises a syringe pump 4301, a bath 4302, a hot plate 4303, and a reaction vessel 4304.
(174) Optionally, in some embodiments, the syringe pump 4301 is configured to deposit the silver-based solution into the reaction vessel 4304. Optionally, in some embodiments, the syringe pump 4301 is configured to deposit a set volume of the silver-based solution into the reaction vessel 4304 at a set rate. Optionally, in some embodiments, the bath 4302 comprises an oil bath. Optionally, in some embodiments, the hot plate 4303 is configured to heat the bath 4302, which heats the reaction vessel 4304. Optionally, in some embodiments, the hot plate 4303 is configured to mix the contents of the reaction vessel 4304 with a stirring rod. Optionally, in some embodiments, the hot plate 4303 is configured to mix the contents of the reaction vessel 4304 with a stirring rod at a rotational velocity of about 10 rpm to about 4,500 rpm. Optionally, in some embodiments, the apparatus further comprises the stirring rod. Optionally, in some embodiments, the reaction vessel 4304 comprises a glass reaction vessel.
(175) Provided herein per FIGS. 44-48 are silver nanoparticles and methods of forming the silver nanoparticles. FIG. 44 shows a TEM image of exemplary silver nanoparticles formed by a first method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure. In some embodiments, the second method of forming silver nanoparticles comprises: forming a first solution comprising a silver based solution, a secondary solvent, and a polymer solution; stirring the first solution; heating the first solution; cooling the first solution; centrifuging the first solution; and washing the first solution. Optionally, in some embodiments, the first solution is cooled to ambient temperature. Optionally, in some embodiments, the polymer solution prevents agglomeration of the silver nanoparticles. In some embodiments, the silver nanoparticles are configured to be used in a conductive silver-based ink. Alternatively, in some embodiments, the silver nanoparticles are configured to be used as a conductive additive in a conductive graphene ink. Optionally, in some embodiments, the small size of the silver nanoparticle enables the conductive silver-based ink to be used by an inkjet printer or in an inkjet printing process.
(176) Optionally, in some embodiments, the silver-based solution comprises a silver-based material comprising AgNO.sub.3. Optionally, in some embodiments, the polymer solution comprises a synthetic polymer. Optionally, in some embodiments, the synthetic polymer comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof. Optionally, in some embodiments, the binder is a dispersant. Optionally, in some embodiments, the binder comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof. Optionally, in some embodiments, the secondary solvent comprises a glycol. Optionally, in some embodiments the glycol comprises ethylene glycol, polyethylene glycol 200, polyethylene glycol 400, propylene glycol, or any combination thereof.
(177) FIG. 45A shows a first image of an exemplary dispersion of silver nanoparticles formed by a first method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure. FIG. 45B shows a second image of an exemplary dispersion of silver nanoparticles formed by a first method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure. Optionally, in some embodiments, the method further comprises redispersing the first solution. The exemplary non-limiting dispersions in FIGS. 45A and 45B comprise a dispersion of the first solution in water. Optionally, in some embodiments, the first solution is redispersed in ethanol, isopropyl alcohol, N-methyl-2-pyrrolidone, cyclohexanone, terpineol, 3-methoxy-3-methyl-1-butanol, 4-hydroxyl-4-methyl-pentan-2-one, methyl isobutyl ketone, or any combination thereof.
(178) FIG. 46A-46F show images of an exemplary apparatus for nanoparticle formation and exemplary first solutions of nanoparticles heated to different temperatures, in accordance with some embodiments. FIG. 46A-46F show images of exemplary first solutions of silver nanoparticles heated to 100° C., 110° C., 120° C., 130° C., 145° C., and 160° C., respectively, in accordance with some embodiments. Per FIG. 46A-46F, it can be seen that higher heating temperatures produce first solutions with silver nanoparticles that are more opaque and white, while lower heating temperatures produce first solutions with silver nanoparticles that are more translucent and yellow.
(179) FIG. 47 shows a TEM image of exemplary silver nanoparticles formed by a second method of silver nanoparticle formation, in accordance with some embodiments of the present disclosure. In some embodiments, the second method of forming silver nanoparticles comprises: heating a secondary solvent; adding a silver-based solution and a polymer solution to the secondary solvent to form a first solution; stirring the first solution; heating the first solution; and washing the first solution. Optionally, in some embodiments, the silver-based solution and the polymer solution are added simultaneously to the secondary solvent. Optionally, in some embodiments, the silver-based solution and the polymer solution are added by a two-channel syringe to the secondary solvent. Optionally, in some embodiments, adding the silver-based solution and the polymer solution to the secondary solvent to form the first solution and stirring the first solution are performed simultaneously. Optionally, in some embodiments, the second method further comprises redispersing the first solution. Optionally, in some embodiments, the first solution is redispersed in water. Optionally, in some embodiments, the polymer solution prevents agglomeration of the silver nanoparticles.
(180) Optionally, in some embodiments, the silver-based solution comprises a silver-based material comprising AgNO.sub.3. Optionally, in some embodiments, the polymer solution comprises a synthetic polymer. Optionally, in some embodiments, the synthetic polymer comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof. Optionally, in some embodiments, the binder is a dispersant. Optionally, in some embodiments, the binder comprises carboxymethyl cellulose, polyvinylidene fluoride, poly(vinyl alcohol), poly(vinyl pyrrolidone), poly(ethylene oxide), ethyl cellulose, or any combination thereof. Optionally, in some embodiments, the secondary solvent comprises a glycol. Optionally, in some embodiments the glycol comprises ethylene glycol, polyethylene glycol 200, polyethylene glycol 400, propylene glycol, or any combination thereof.
(181) Finally, provided herein are conductive silver-based films comprising a substrate and a conductive silver-based ink. Optionally, in some embodiments, the conductive silver-based ink comprises silver nanowires, silver nanoparticles, or both. Optionally, in some embodiments, the conductive silver-based ink is a conductive silver-based hydrate. In some embodiments, the silver nanoparticles are configured to be used in a conductive silver-based ink. Alternatively, in some embodiments, the silver nanoparticles are configured to be used as a conductive additive in a conductive graphene ink. Optionally, in some embodiments, the small size of the silver nanoparticle enables the conductive silver-based ink to be used by an inkjet printer or in an inkjet printing process.
(182) FIG. 48 shows an I-V curve of an exemplary film comprising an exemplary conductive silver-based ink, in accordance with some embodiments of the present disclosure. The I-V curve, per FIG. 48, indicates that the conductive silver-based inks formed by the methods herein exhibit high energy storage and transmission capability and are configured to increase the electrical performance of conductive silver-based inks and conductive films formed therewith. Additionally, exemplary films comprising the exemplary conductive silver-based inks herein exhibit a sheet resistance of about 7 μΩ.Math.cm to about 28 μΩ.Math.cm. In some embodiments, a conductive film formed from the conductive silver-based inks herein exhibit a sheet resistance of about 14 μΩ.Math.cm.
(183) Optionally, in some embodiments, the conductive silver-based ink comprises silver nanowires, wherein the conductive silver-based film has a sheet resistance of about 0.3 ohm/sq/mil to about 1.8 ohms/sq/mil. Optionally, in some embodiments, the conductive silver-based ink comprises silver nanoparticles, wherein the conductive film has a sheet resistance of about 0.01 ohm/sq/mil to about 0.04 ohm/sq/mil.
Terms and Definitions
(184) Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Any reference to “or” herein is intended to encompass “and/or” unless otherwise stated.
(185) As used herein, and unless otherwise defined, the term “about” refers to a range of values within plus and/or minus 10% of the specified value.
(186) As used herein, and unless otherwise specified, the term RGO refers to reduced graphene oxide.
(187) As used herein, and unless otherwise specified, the term SEM refers to a scanning electron microscopy.
(188) As used herein, and unless otherwise specified, the term TEM refers to a transmission electron microscopy.
(189) As used herein, and unless otherwise specified, the term RFID refers to radio frequency identification.
(190) As used herein, the term “percolation threshold” refers to a mathematical concept representing the formation of long-range connectivity in random systems. Below the threshold a giant connected component does not exist; while above it, there exists a giant component of the order of system size.
(191) As used herein, the term “molecular weight” refers to an average molecular weight, a peak average molecular weight, a number average molecular weight, or a weight average molecular weight.
(192) While preferable embodiments of the present methods and devices taught herein have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the methods and devices taught herein. It should be understood that various alternatives to the embodiments of the methods and devices taught herein described herein may be employed in practicing the methods and devices taught herein. It is intended that the following claims define the scope of the methods and devices taught herein and that methods and structures within the scope of these claims and their equivalents be covered thereby.
NON-LIMITING EXAMPLES
(193) In one non-limiting example of silver nanowire synthesis, 50 mL of ethylene glycol was added to the reaction vessel with a stir bar. The vessel was then suspended in an oil bath and heated at 155° C. for 1 hour under magnetic stirring at 200 rpm. An amount of 400 μL of 4 mM CuCl.sub.2/ethylene glycol solution were then added, and the solution was heated and stirred continuously for additional 15 minutes to ensure a homogenous solution. An amount of 15 mL of 0.147 M poly(vinyl pyrrolidone), sodium dodecyl sulfonate, vitamin B2, poly(vinyl alcohol), dextrin, and poly(methyl vinyl ether) with a molecular weight of 20,000 was then dissolved in an ethylene glycol solution and was then injected into the reaction vessel. Finally, 15 mL of 0.094 M AgNO.sub.3/ethylene glycol solution was injected into the solution immediately or over the course of 15 minutes. The solution was allowed to react for 1 hour before it was cooled to room temperature. The silver nanowires were collected by centrifuging the solution at 3,000 rpm for 20 minutes and washing with ethanol. This washing process was repeated 3 times to remove excess ethylene glycol and poly(methyl vinyl ether). The final silver product was re-dispersed and stored in ethanol.
(194) In another non-limiting example of silver nanowire synthesis, 500 mL of ethylene glycol was added to the reaction vessel to which a stir bar was added; the vessel was then suspended in an oil bath and heated at 120° C. for 1 hour under magnetic stirring (200 rpm). This was followed by the addition of 4 mL of 4 mM CuCl.sub.2/ethylene glycol solution. The solution was then heated and stirred continuously for additional 15 minutes to ensure a homogenous solution. Then, 150 mL of 0.147 M poly(vinyl pyrrolidone) (molecular weight 20,000) dissolved in an ethylene glycol solution was injected into the reaction vessel using a burette. Lastly, 150 mL of 0.094 M AgNO.sub.3/ethylene glycol solution was injected slowly to the hot solution; this step was accomplished using syringe pump where the solution was fed into the solution at a rate of 70 mL/hour. All of the AgNO.sub.3 solution was injected in the course of 130 minutes. To allow for the growth of silver nanowires, the reaction temperature was then increased to 160° C. and maintained at this temperature for 1 hour. The resulting silver was collected by centrifugation at 5000 rpm for 10 minutes and washed with acetone. This washing process was repeated 2 times (one with water, the other with ethanol) to remove excess ethylene glycol and poly(vinyl pyrrolidone). The final silver product was re-dispersed and stored in ethanol.
(195) In a non-limiting example of silver nanoparticle synthesis, silver nitrate (AgNO.sub.3) was dissolved in ethylene glycol along with poly(vinyl pyrrolidone) (molecular weight=20,000). Then, 330 mL of ethylene glycol was mixed with 200 mL of 0.25 M AgNO.sub.3 and 200 mL of poly(vinyl pyrrolidone) with concentrations from 0.027 M and up to 0.37 M in ethylene glycol. This solution was stirred in the reactor shown in the next slide, followed by heating at 160° C. When the final temperature is attained, the reaction was maintained at this temperature for 45 more minutes to allow for the growth of silver nanoparticles. After the completion of the reaction, the solution was cooled down to room temperature, and silver nanoparticles were collected by centrifugation and then washed with ethanol several times.
(196) In another non-limiting example of silver nanoparticle synthesis, a precursor solution was injected into preheated solvent in the reactor. Ethylene glycol (330 mL) was added to a 1 L three-neck round bottom flask, heated with stirring in an oil bath at 160° C. for 1 hour. After 60 minutes, AgNO.sub.3 (200 mL of a 0.25 M solution in ethylene glycol) and poly(vinyl pyrrolidone) (200 mL of a 0.37 M solution in ethylene glycol calculated based on molar mass of a repeating unit) were simultaneously added with a two-channel syringe pump at a rate of 20 mL/min to the stirring solution. The reactor was further heated to 160° C. and maintained at this temperature for 45 more minutes. Samples were washed with ethanol and re-dispersed in water for analysis
