Microwave synthesis of a CoSe2/graphene–TiO2 heterostructure for improved hydrogen evolution from aqueous solutions in the presence of sacrificial agents

Abstract

A heterogeneous material consisting of a tube type TiO₂ was grown in the presence of a CoSe₂/graphene hybrid, as a high-performance photocatalyst material, through a fast microwave-assisted technique. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopic analysis, UV-vis absorbance spectra and UV-vis diffuse reflectance spectra (DRS) analysis. The hydrogen evolution rate for ternary composites was found to be markedly high compared to bare TiO₂ and binary CoSe₂/graphene composites. This extraordinary photocatalytic activity for hydrogen evolution arises from the positive synergistic effect between the CoSe₂ and graphene components in our heterogeneous system. The optical properties were also found to be affected by the different weight% of graphene in the composites by observing their respective band gaps from the DRS spectra.