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

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.