Hierarchical CdMoO4 nanowire–graphene composite for photocatalytic hydrogen generation under natural sunlight

Abstract

Herein, a facile in situ solvothermal technique for the synthesis of a CdMoO₄/graphene composite photocatalyst is reported. Graphene oxide (GO) was synthesised by an improved Hummers' method and was further used for the in situ synthesis of graphene via GO reduction and the formation of a CdMoO₄ nanowire/graphene composite. The structural phase formation of tetragonal CdMoO₄ was confirmed from X-ray diffraction measurements. The small nanoparticle assembled nanowires, prismatic microsphere morphology and crystalline nature of the synthesized material were investigated using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Due to its unique morphology and stability, the CdMoO₄/graphene composite was used as a photocatalyst for H₂O splitting. In comparison to pristine CdMoO₄, the CdMoO₄/graphene composite showed the best hydrogen evolution rate, i.e. 3624 μmole h⁻¹ g⁻¹, with an apparent quantum yield of 30.5%. The CdMoO₄/graphene composite has a higher photocatalytic activity due to the inhibition of charge carrier recombination. H₂ production measurements showed that the ternary semiconductor/graphene composite has enhanced photocatalytic activity for H₂ generation.