Transition metal functionalized graphene is good candidate for hydrogens storage material [1-3]. Transition metal atoms interact with carbon of substrate material through Dewar [4] and hydrogen molecules with Kubas [5] interaction and offer good binding energy. However due to higher cohesive energy of transition metals, synthesis of such material remains bottleneck. Boron-doping into graphene has been studied [6-8] to eliminate clustering of transition and alkali metal atoms. In this work, an alternate approach of using graphene oxide as base material is studied. Hydrogen adsorption in vanadium decorated graphene oxide is studied with density functional theory calculations based on generalized gradient approximation. The epoxyl and hydroxyl groups in graphene oxide can provide active sites for the binding of vanadium and help to mitigate the clustering problem. From the preliminary calculations, it is found that graphene oxide has very high binding energy of ~6.2 eV for vanadium, higher than the cohesive energy of vanadium (5.31 eV). Further, single vanadium atom can bind four H₂ molecules with an average adsorption energy of -0.5 eV. Graphene oxide is easy to synthesis and based on the value of vanadium binding energy it is easy to decorate with vanadium. Thus, vanadium decorated graphene oxide is promising material for hydrogen storage material.

References:

1. Yildirim T, Ciraci S. Titanium-decorated carbon nanotubes as a potential high-capacity hydrogen storage medium. Physical review letters. 2005 May 5;94(17):175501.
2. Zhao Y, Kim YH, Dillon AC, Heben MJ, Zhang SB. Hydrogen storage in novel organometallic buckyballs. Physical review letters. 2005 Apr 22;94(15):155504.
3. Durgun E, Ciraci S, Yildirim T. Functionalization of carbon-based nanostructures with light transition-metal atoms for hydrogen storage. Physical Review B. 2008 Feb 4;77(8):085405.
4. Mingos DM. A historical perspective on Dewar's landmark contribution to organometallic chemistry. Journal of Organometallic Chemistry. 2001 Oct 15;635(1):1-8.
5. Kubas Gregory J. Molecular hydrogen complexes: coordination of a. sigma. bond to transition metals. Accounts of Chemical Research. 1988 Mar;21(3):120-8.
6. Park HL, Chung YC. Hydrogen storage in Al and Ti dispersed on graphene with boron substitution: First-principles calculations. Computational Materials Science. 2010 Oct 31;49(4): S297-301.
7. Beheshti E, Nojeh A, Servati P. A first-principles study of calcium-decorated, boron-doped graphene for high capacity hydrogen storage. Carbon. 2011 Apr 30;49(5):1561-7.
8. Tokarev A, Avdeenkov AV, Langmi H, Bessarabov DG. Modeling hydrogen storage in boron‐substituted graphene decorated with potassium metal atoms. International Journal of Energy Research. 2015 Mar 25;39(4):524-8.