MESOPOROUS MATERIALS FROM NANOPARTICLE ENHANCED POLYSACCHARIDES

Abstract

There is described a mesoporous composite material comprising carbon nanoparticles dispersed in a mesoporous carbonaceous material.

Claims

1. A mesoporous composite material comprising carbon nanoparticles dispersed in a mesoporous carbonaceous material.

2. A mesoporous composite material according to claim 1 wherein the carbon nanoparticles are substantially homogenously dispersed in the mesoporous carbonaceous material.

3. A mesoporous composite material according to claim 1 or 2 wherein the carbon nanoparticles are based on one or more of graphene, graphene oxide, graphite and carbon nanotubes.

4. A mesoporous composite material according to claim 3 wherein the carbon nanoparticles are based on graphene or graphene oxide.

5. A mesoporous composite material according to any one of the preceding claims wherein the carbon nanoparticles are based on graphite.

6. A mesoporous composite material according to any one of claims 1 to 4 wherein the carbon nanoparticles are based on carbon nanotubes.

7. A mesoporous composite material according to any one of the preceding claims wherein the mesoporous carbonaceous material is derived from one or more mesoporous polysaccharides.

8. A mesoporous composite material according to claim 7 wherein the mesoporous carbonaceous material is produced by the carbonisation of one or more mesoporous polysaccharides.

9. A mesoporous composite material according to any one of the preceding claims wherein the mesoporous composite material precursor is in the form of a stable organic gel before the carbonisation step.

10. A mesoporous composite material according to any one of the preceding claims wherein the C:O ratio is tuneable.

11. A mesoporous composite material according to any one of the preceding claims wherein the composite material is shaped in different forms.

12. A mesoporous composite material according to claim 11 wherein the composite material is a monolith with a tuneable micro-/mesopore structure throughout.

13. A mesoporous composite material according to any one of the preceding claims wherein the material has a tailored pore distribution.

14. A mesoporous composite material according to any one of the preceding claims wherein the material has improved electrical conductivity.

15. A mesoporous composite material according to any one of the preceding claims wherein the material has improved thermal conductivity.

16. A mesoporous composite material according to any one of the preceding claims wherein the material has improved absorption in the electromagnetic spectrum.

17. A mesoporous composite material according to any one of the preceding claims wherein the material incorporates extra functionality via specific functionalisation on the nanoparticle surface.

18. A mesoporous composite material according to any one of claims 1 to 15 wherein the material incorporates extra functionality via temperature mediated carbonisation of the polysaccharide or the polysaccharide/nanoparticle hybrid.

19. A mesoporous composite material according to any one of the preceding claims wherein the material has controllable macroporosity (density).

20. A method of preparing a mesoporous composite material comprising carbon nanoparticles dispersed in a mesoporous carbonaceous material according to claim 1, said method comprising: dispersion of the carbon nanoparticles in a molten carbonaceous material.

21. A method of preparing a mesoporous composite material according to claim 19 wherein the mesoporous carbonaceous material is prepared by solvent exchange and drying of the carbonaceous material.

22. A mesoporous composite material, method, as herein described with reference to the accompanying description, examples and figures.

Description

[0055] The invention will now be described by way of example only and with reference to the accompanying figures in which:

[0056] FIG. 1 illustrates Raman spectra of mesoporous nanocomposites from starch (mnfst) carbonised at 800° C. following the procedure described in Examples 2 to 4: (a) mnfst-graphene (0.23% wt.), (b) mnfst-graphite(0.3% wt.), (c) mnfst-GO(1% wt.), (d) mnfst-GO(1% wt.) (Note//not made according to Example 2), (e) mesoporous carbonaceous material made using the same method without incorporating nanoparticles.

[0057] FIG. 2 is an SEM of a mesoporous nanocomposite from starch-GO (1% wt.) carbonised to 800° C.;

[0058] FIG. 3 is an SEM of a mesoporous nanocomposite from starch-graphite (5% wt.) carbonised to 800° C.;

[0059] FIG. 4 is a plot of Capacitance (F g.sup.−1) versus Scan rate (mV s.sup.−1) obtained from cyclic voltammograms for St-graphite(3% wt.) made according to Example 5, and a mesoporous carbonaceous material made using the same method without incorporating nanoparticles.

[0060] FIG. 5 is a plot of Capacitance (F g.sup.−1) versus Cycle number obtained from Galvanostatic charge-discharge experiments for starch graphite (St-graphite) (3% wt.) made according to Example 5, and a mesoporous carbonaceous material, Starbon 800 (St800) made using the same method without incorporating nanoparticles.

[0061] FIG. 6 is an HTEM of graphene doped sample (0.23 wt. %)

[0062] FIG. 7 is an HTEM of carbonaceous materials with dispersed graphite

RESULTS AND EXAMPLES

Example 1

Solvent Exchange Method

[0063] Incorporating sulfolane to a starch aqueous gel produces a starch- water-sulfolane gel. Distillation at 40° C. under vacuum produces a starch-sulfolane gel. Incorporating toluene produces a starch-toluene gel. Addition of p-toluenesulfonic acid (TsOH) and subsequent carbonisation produces a mesoporous carbonaceous material, and a sulfolane-toluene mixture. On carbonisation of the starch-toluene gel, toluene is recovered, and on distillation of the sulfolane-toluene mixture, both solvents are also fully recovered.

Example 2

Monolithic Mesoporous Materials

[0064] A method for preparation of monolithic mesoporous materials from polysaccharide precursors and carbon based nanoparticles, and chemically functionalised carbon based nanoparticles. In this case a mixture of graphene oxide (1 wt. %) with starch was employed using the method detailed in paragraphs [0021] and [0022]. The starch-GO mixture (5 g) and 25 ml 4of water was added to a 35 ml microwave vial. And the following experimental procedure employed: The contents of the vial were heated in a CEM discover laboratory microwave at 140° C. for 1 minute. TsOH was then added to the contents and the mixture was sonicated for 3 minutes and then poured into moulds that were maintained at 5° C. for 24 hours. Subsequently, the shaped solid gel was placed in a vacuum tube and sulfolane was added in sufficient quantity to cover the material. The tube was then placed under vacuum and heated from 20 to 80° C. in 10° C. increments over a period of 10 hours. The sulfolane was then removed and toluene added, it was heated at 70° C. for 1 hour and held at 50° C. for 12 hours. The toluene was then removed and the sample placed in a vacuum oven at 70° C. for 24 hours. The sample was then carbonised by heating under vacuum according to the following program: 1° C./min to 120° C., 0.2° C./min to 180° C., hold for 4 hours, 0.2° C./min to 300° C., hold for 3 hours, 0.3° C./min to 400° C., 1° C./min to 800° C.

[0065] The material obtained as a monolith had a total pore volume higher than 0.4 ml/g with degree of mesoporosity higher than 85%, a density of 0.5 gcm.sup.−3 and a conductivity of 660 Sm.sup.−1. The morphology of this material can be observed in the SEM image of FIG. 2, and characteristic bands are observed in the Raman spectrum in FIG. 1c.

Example 3

Monolithic Mesoporous Materials

[0066] Material was prepared as Example 2, but with a graphene content of 0.23 wt. %. The starch-rGO mixture (5 g) and 25 ml of water was added to a 35 ml microwave vial. The subsequent experimental procedure employed was as in Example 2.

[0067] The material obtained as a monolith has total pore volume higher than 0.4 ml/g with degree of mesoporosity higher than 85%, a density of 0.22 gcm.sup.−3 and a conductivity of 366 Sm.sup.−1. Characteristic bands are observed in the Raman spectrum in FIG. 1a.

Example 4

Monolithic Mesoporous Materials

[0068] Material was prepared as Example 2, but with a graphite content of 0.3 wt. %. Starch and graphite were premixed and ball-milled for 1 hour at 500 rpm. The starch-graphite mixture (5 g) and 25 ml of water was added to a 35 ml microwave vial. The subsequent experimental procedure employed was as in example 2.

[0069] The material obtained as a monolith has total pore volume higher than 0.4 ml/g with degree of mesoporosity higher than 85%, a density of 0.25 gcm.sup.−3 and a conductivity of 255 m.sup.−1. Characteristic bands are observed the Raman spectra in FIG. 1b.

Example 5

Monolithic Mesoporous Materials

[0070] Material was prepared as Example 2, with a graphite content of 3 wt. %. Starch and graphite were premixed and ball-milled for 30 minutes at 500 rpm. The starch-graphite mixture (5 g) and 25 ml of water was added to a 35 ml microwave vial. The subsequent experimental procedure employed was as in example 2.

[0071] The material obtained as a monolith has total pore volume higher than 0.4 ml/g with degree of mesoporosity higher than 85% and a capacitance greater than 125 Fg.sup.−1 (cyclic voltammetry) (see FIG. 4) at a scan rate of 2 mV using 2.0 M H.sub.2SO.sub.4 solution as the electrolyte and greater than 99% capacitance retention after 10000 cycles (galvanostatic charge/discharge experiments) (see FIG. 5).

Example 6

Monolithic Mesoporous Materials

[0072] Material was prepared as Example 2, with a graphite content of 5 wt. %. Starch and graphite were premixed and ball-milled for 1 hour at 500 rpm. The starch-graphite mixture (5 g) and 25 ml of water was added to a 35 ml microwave vial. The subsequent experimental procedure employed was as in example 2.

[0073] The material obtained as a monolith has total pore volume higher than 0.4 ml/g with degree of mesoporosity higher than 85%, a density of 0.15 gcm.sup.−3 and a conductivity of 461 Sm.sup.−1. The morphology of this material can be observed in the SEM image of FIG. 3.

Example 7

Textural Properties of the Proposed Materials

[0074] Information about textural properties of some of the examples of obtained mesoporous carbonaceous composite materials derived from native polysaccharides incorporating carbon-based nanoparticles is shown in Table 1.

TABLE-US-00001 TABLE 1 Average Carbon-based Loading S.sub.BET V Pore diameter nanoparticle (%) (m.sup.2g.sup.−1) (cm.sup.3g.sup.−1) (nm) Graphene oxide 1 241 1.22 9.3 Graphene 0.23 390.7 1.44 7.7 Graphite 5 448 0.52 5.3 Graphite 0.3 251.9 1.05 8.9

Example 8

High-Resolution Transmission Electron Microscopy

[0075] Information about distribution of carbon nanoparticles within carbonaceous matrix for some of the examples is shown in FIGS. 6 and 7 herein.

Competitors

[0076] 1. Mesoporous carbon composite containing carbon nanotube; EP 1686106 B 1

REFERENCES

Patent References

[0077] P1 Worldwide Patent WO2007104798 A3, Nov. 1 2007 “Mesoporous carbonaceous materials, preparation and use thereof” [0078] P2 Worldwide Patent WO2004041915 A1 “Method to produce graphite/polymer composites” [0079] P3 Chinese Patent CN 103342348 A, Jun. 14 2013 “Preparation method for graphene/carbon microsphere composite” [0080] P4 Chinese Patent CN102544459A, Jan. 12 2012 “Method for preparing graphene-coated carbon microsphere material by coating graphene oxide on carbon microsphere” [0081] P5 European Patent EP 0109839 B1, Sep. 6 1989 “Method of making graphite electrodes”

Non-Patent References

[0082] 1 Knox J H, Ross P: Carbon-based packing materials for liquid chromatography-structure, performance, and retention mechanisms. Advances in Chromatography, Vol 37 1997; 37:73-119. [0083] 2 Kruk M, Jaroniec M, Ryoo R, Joo S H: Characterization of ordered mesoporous carbons synthesized using mcm-48 silicas as templates. Journal of Physical Chemistry B 2000; 104:7960-7968. [0084] 3 Hu Z H, Srinivasan M P, Ni Y M: Novel activation process for preparing highly microporous and mesoporous activated carbons. Carbon 2001; 39:877-886. [0085] 4 Zhang F Q, Meng Y, Gu D, Yan Y, Yu C Z, Tu B, Zhao D Y: A facile aqueous route to synthesize highly ordered mesoporous polymers and carbon frameworks with ia(3)over-bard bicontinuous cubic structure. Journal of the American Chemical Society 2005; 127:13508-13509. [0086] 5 Karimi B, Biglari A, Clark J H, Budarin V: Green, Transition-Metal-Free Aerobic Oxidation of Alcohols Using a Highly Durable Supported Organocatalyst. Angewandte Chemie International Edition, 46, 7210-7213 (2007) DOI: 10.1002/anie.200701918 [0087] 6 Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. “Electric Field Effect in Atomically Thin Carbon Films”, Science 306 (5696): 666-669 (2004). doi:10.1126/science.1102896 [0088] 7 Salavagione, Horacio J; Martinez Gerardo, Ellis, Gary, Graphene-Based Polymer Nanocomposites, in Physics and Applications of Graphene -Experiments (Ed: Mikhailov, Sergey), InTech Publishing, Rijeka, Croacia Vol. 1, Cap. 9, p.169-192 (2011) ISBN: 978-953-307-217-3 [0089] 8 Ŝupová, M; Martynková, Gra{circumflex over (z)}yna S; Barabaszová, K. “Effect of Nanofillers Dispersion in Polymer Matrices: A Review”, Sci. Advanced Mater., 3 (1), 1-25 (2011) doi: 10.1166/sam.2011.1136 [0090] 9 “Polysaccharide Nanocomposites Reinforced with Graphene Oxide and Keratin-Grafted Graphene Oxide”, Ind. Eng. Chem. Res., 51, 3619-3629 (2012) dx.doi.org/10.1021/ie200742x [0091] 10 a) “Raman Spectrum of Graphene and Graphene Layers”, Phys. Rev. Lett. 97, 187401 (2006) dx.doi.org/10.1103/PhysRevLett.97.187401. [0092] 10 b) Yan Wang, Daniel C. Alsmeyer, and Richard L. McCreery, Chem. Mater, 1990, 2, 557-563 “Raman Spectroscopy of Carbon Materials: Structural Basis of Observed Spectra”