Nanocomposite based on graphene for reversible storage of hydrogen

Abstract

A nanocomposite for the reverse storage of hydrogen based on monolayer sheets of polycrystalline or monocrystalline grapheme having a form of a cylindrical spiral roll of polycrystalline or monocrystalline graphene with a preferably constant spacing in the range from 0.2 to 2 nm, whereby the said spiral roll of polycrystalline graphene has grains with a minimum diameter of 50 nm.

Claims

1. A nanocomposite for the reverse storage of hydrogen in the form of a cylindrical spiral roll which is made from at least a single monolayer sheet of polycrystalline or monocrystalline functionalized graphene with constant separating spacing, wherein the cylindrical spiral roll is wound up onto a carbon core with a diameter in the range of 1 nm to 20 m; the cylindrical spiral roll is composed of at most 50 000 polycrystalline or monocrystalline functionalized graphene sheets; the cylindrical spiral roll has a separating spacing in the range of 0.2 to 2 nm; the cylindrical spiral roll has an external diameter in the range of 500 nm to 5 mm; the cylindrical spiral roll has a width in the range of 0.05 to 1000 mm; the cylindrical spiral roll has functionalized graphene grains with a minimum diameter of 50 nm; the separating spacing is maintained by metal carbide particles and/or non-metal carbide particles that are located in the space between consecutive layers and that cover from 0.1% to 5% of the inner surface of the cylindrical spiral roll; the particles of carbides contain from 1 to 5 molecules; the carbides are selected from the group consisting of Ca, Al, Li, B and Si carbide; and the nanocomposite has a minimum hydrogen storage capacity under a pressure of 5 MPa of 6.5 wt %, wherein the functionalized graphene sheets are formed by functionalizing the graphene sheets with the carbide particles on a single layer of graphene formed on a bimetallic substrate of copper and platinum, after which the copper is selectively etched.

2. The nanocomposite according to claim 1, wherein when: the cylindrical spiral roll is 100 mm wide and with the diameter of 30 m, is made from a single monolayer sheet of polycrystalline graphene that is wound up onto a carbon core with a diameter of 5 m; the monolayer sheet of polycrystalline graphene has grains with size ranging from 100 to 120 nm; the monolayer sheet of polycrystalline graphene measuring 100600 mm is functionalized with Al.sub.4C.sub.3 particles which cover 2.04% of the inner surface of the cylindrical spiral roll; the width of the separating spacing of the cylindrical spiral roll is 0.59 nm; and the cylindrical spiral roll has a hydrogen content of 16 ppm, which is equivalent to about 7.0 wt. % of hydrogen.

3. The nanocomposite according to claim 1, wherein when: the cylindrical spiral roll is 100 mm wide and with the diameter of 65 m, is made from five monolayer sheets of polycrystalline graphene joined by thermal welding and wound up onto a carbon core with the diameter of 8 m; the monolayer sheets of polycrystalline graphene have grains with size ranging from 100 to 120 nm; the monolayer sheets of polycrystalline graphene measuring 100600 mm are functionalized with SiC particles which cover 4% of the inner surface of the cylindrical spiral roll; and the width of the separating spacing of the cylindrical spiral roll is 0.68 nm; and the cylindrical spiral roll has a hydrogen content of 16 ppm, which is equivalent to about 6.5 wt. % of hydrogen.

4. The nanocomposite according to claim 1, wherein the carbide particles are of Al.sub.4C.sub.3.

5. The nanocomposite according to claim 1, wherein the carbide particles are of SiC.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 illustrates a partially unwound roll of the nanocomposite in a perspective view.

DETAILED DESCRIPTION OF THE INVENTION

(2) The proposed invention will be outlined in detail on the basis of the examples of embodiment shown in a drawing representing a partially unwound roll of the nanocomposite in a perspective view.

(3) The spiral layers of the roll are wound on a core and have a shape approximating the Archimedean spiral. The internal surface of the roll is coated with functionalizing particles.

(4) The indicators shown in the drawing denote the following parameters: Adiameter of the core and external fiber, Bwidth of the graphene sheet, Clength of the core and external fiber, and Dpitch of the spiral.

Example 1

(5) A multilayered sheet measuring 100600 mm, containing on the external surface a single layer of polycrystalline graphene with a grain size ranging between 100 to 120 nm, formed on a bimetallic substrate of copper and platinum, was placed in the vacuum chamber of a plasma-chemical reactor equipped with pulsed laser and a target made of aluminum carbide Al.sub.4C.sub.3. After reducing the pressure in the reactor chamber to the level of 10.sup.6 Pa, three nanosecond laser pulses were focused onto the target surface, causing Al.sub.4C.sub.3 ablation and applying particles separated from the target to the graphene-side exposed surface of the plate. After removing the plate from the reactor chamber a polymethyl methacrylate film was attached to the plate surface and copper was selectively etched from the space between platinum and PMMA, obtaining a graphene sheet functionalized with Al.sub.4C.sub.3 particles, on a PMMA carrier, measuring 100600 mm. Carbon cores, 140 mm long and with a diameter of 5 m, were then attached by thermal welding to the two short sides of the graphene sheet. The PMMA carrier was subsequently dissolved in acetone and dried. Functionalized graphene was then rolled into a spiral roll, at which point the external fiber was separated by cutting, and the core section extending beyond the roll was severed. The roll thus prepared was heated under a vacuum of 10.sup.6 Pa at a temperature of 600 C. for 15 minutes. Ultimately, a roll was obtained with the following parameters: external dimensionsdiameter: 30 m, length: 100 mm, weight66 g, density0.76 g/cm.sup.3. By comparing the external diameter of the roll and the diameter of the core, the pitch of the spiral line of functionalized graphene was determined to be 0.59 nm. Analyzing the density of the roll and taking into account the weight of the carbon fiber and the weight of the graphene layer, it was estimated that Al.sub.4C.sub.3 particles had functionalized ca. 2.04% of the internal surface of the roll.

(6) The roll of functionalized polycrystalline graphene thus produced was then subjected to hydrogen (99.996% pure) at a pressure of 5 MPa. Subsequently, an assessment was performed of the quantity of hydrogen absorbed by a roll weighing 66 g, by conducting measurements of IR energy absorption after complete combustion in a stream of inert gas. The weight of the test sample was complemented by a blind sample of spectrally pure silicon. The blind sample weighed ca. 250 mg. The analysis of hydrogen content produced the result of 16 ppm, whichwith respect to the weight of the analyzed sampleis equivalent to ca. 7 wt. % of hydrogen.

Example 2

(7) Five multilayered sheets measuring 100600 mm, containing on the external surface a single layer of polycrystalline graphene with a grain size ranging from 100 to 120 nm, formed on a bimetallic substrate of copper and platinum, were placed successively in the vacuum chamber of a plasma-chemical reactor equipped with a two-electrode target composed of amorphous silicon carbide (SiC) and a spark-ignited target spraying system based on the discharges of a 4 F capacitor. After reducing the pressure in the reactor chamber to the level of 10.sup.6 Pa and filling it with argon to the pressure of 10 hPa, five cycles of capacitor charging and spark-activated discharging were performed, achieving SiC ablation and applying particles separated from the target to the graphene-side exposed surface of the plate. After removing the plate from the reactor chamber a polymethyl methacrylate film was attached to the plate surface and copper was selectively etched from the space between platinum and PMMA, obtaining a graphene sheet functionalized with SiC particles, on a PMMA carrier, measuring 100600 mm. Carbon cores, 140 mm long and with a diameter of 8 m, were then attached by thermal welding to the two short sides of each graphene sheet. The PMMA carrier was then dissolved in acetone and the sheet was dried. The first functionalized graphene sheet was then rolled into a spiral roll, at which point the external fiber was separated by cutting. Subsequent sheets were first thermally attached to the roll, whereupon the initial fiber was cut off and roll winding was continued. After the fifth sheet was wound up the last external fiber was detached and the core section extending beyond the roll was cut off. The roll thus prepared was heated under a vacuum of 10.sup.6 Pa at a temperature of 680 C. for 15 minutes. Ultimately, a roll was obtained with the following parameters: external dimensionsdiameter: 65 m, length: 100 mm, weight340 g, density1.02 g/cm.sup.3. By comparing the external diameter of the roll and the diameter of the core, the pitch of the spiral line of functionalized graphene was determined to be 0.68 nm. Analyzing the density of the roll and taking into account the weight of the carbon fiber and the weight of the graphene layer, it was estimated that SiC particles had functionalized ca. 4% of the internal surface of the roll.

(8) The roll of functionalized polycrystalline graphene thus produced was then subjected to hydrogen (99.996% pure) at a pressure of 5 MPa. Subsequently, an assessment was performed of the quantity of hydrogen absorbed by a roll weighing 340 g, by conducting measurements of IR energy absorption after complete combustion in a stream of inert gas. The weight of the test sample was complemented by a blind sample of spectrally pure silicon. The blind sample weighed ca. 250 mg. The analysis of hydrogen content produced the result of 16 ppm, whichwith respect to the weight of the analyzed sampleis equivalent to ca. 6.5 wt. % of hydrogen.