Photocatalytic Hydrogen Evolution by Flexible Graphene Composites Decorated with Ni(OH)2 Nanoparticles

This work presents the hydrogen evolution produced by flexible graphene composites (FGCs) fabricated by a casting method. Ni(OH)(2) nanoparticles were also grown on the FGCs by using a wet chemical method. Those nanoparticles present spherical shapes and are uniformly distributed on the surface of the FGCs. The hydrogen generation activity in water for the FGCs with and without Ni(OH)(2) nanoparticles was produced by UV light excitation. The FGCs decorated with Ni(OH)(2) nanoparticles had a hydrogen generation rate 2.66 times higher than the FGCs without nanoparticles. It was also observed that the surface of the FGCs is oxidized during the photocatalytic process (formation of graphene oxide); this in turn helped to create actives sites for the generation of the electron hole pairs during the irradiation under UV light and to transfer of charge from the FGCs' surface to the electron trapping centers (Ni(OH)(2) nanoparticles). Further, reuse experiments of the FGCs demonstrated that their stability for the hydrogen generation improved due to the presence of Ni(OH)(2) nanoparticles, since the hydrogen generation rate after three cycles of use decreased by 46% and by 84% in the FGCs with and without Ni(OH)(2) nanoparticles, respectively. The flexibility of the graphene composites facilitated their introduction and removal from the water container where the photocatalytic generation of H-2 occurred. Hence, our results suggest that the FGCs could be a feasible option for water splitting in industrial reactors.