Effect of transition metal oxide nanoparticles on gas adsorption properties of graphene nanocomposites

Porous carbon-based materials suffer from weak binding energies with gas molecules. These weak bindings limit the gas adsorption capacity of the adsorbents especially at room temperature conditions. Current functionalization methods that are used to improve the gas uptake of these systems mostly rely on the introduction of noble and transition metals to the substrate. In this work, we studied the adsorption of H-2 and CO2 gases onto reduced graphene oxide (RGO) decorated by transition metal oxides of TiO2, NiO, Fe3O4 and CuO (named as RGO-X nanocomposites, X: Ti, Ni, Fe, and Cu). Results of hydrogen adsorption isotherms at 298 K and 328 K gave rise to calculated adsorption energies of 9-13 kJ/mol. The enhanced adsorption strengths sorted as RGO-Ti > RGO-Ni > RGO-Fe > RGO-Cu led to hydrogen uptakes of 10-20 mu g/m(2) in RGO-X nanocomposites compared to that of 2 mu g/m(2) in RGO. Results of CO2 adsorption also showed the high potential of TiO2 among studied transition metal oxide nanoparticles as active sites for CO2 adsorption.