Polymer supported graphene-CdS composite catalyst with enhanced photocatalytic hydrogen production from water splitting under visible light

A polymer supported graphene structure was synthesized using organic microspheres as the support of the graphene oxide. Graphene oxide was reduced to graphene and CdS was decorated on the surface of the graphene through a solvothermal process. The photocatalytic hydrogen production reaction was carried out using the composite catalyst under visible light irradiation (lambda > 400 nm). A series of composite catalysts were synthesized with different reaction time. The maximal hydrogen production rate of 175 mu mol h(-1) was obtained from the 3 h prepared sample (PSGM/rGO/CdS-3), which is 19.3 times higher than the mechanical mixing sample with the same composition. The quantum efficiency of the PSGM/rGO/CdS-3 sample was 3.99% at 420 nm. Graphene served as electron acceptor and hydrogen evolution sites to promote the separation of the photo-induced charge carriers. Quantum size effect was observed from ultraviolet-visible diffuse reflectance spectroscopy and PL measurements. The presence of quantum size effect widened the bandgap of the catalyst and enhanced the photocatalytic hydrogen production rate. The stability of the composite catalyst was tested and demonstrated that this graphene-based composite catalyst was a stable and potential catalyst for photocatalytic hydrogen production. (C) 2015 Elsevier B.V. All rights reserved.