Composite nanostructures of black TiO2/WO3 on rGO nanosheets for photoelectrochemical water splitting

Abstract

A uniform dispersion of black TiO2 nanoparticles and WO3 nanorods on rGO nanosheets was assessed for its photoelectrochemical water splitting activity. A facile solution-based approach was employed to synthesize the black TiO2 nanoparticles and WO3 nanorods, whereas the modified Hummer's method was used to prepare the rGO nanosheets. The composite nanostructure was obtained using a solvothermal approach. Visible light absorption was improved significantly, and the bandgap was narrowed for nanocomposites (1.76 eV) than W-TiO2 nanoparticles (3.10 eV). The structural changes were validated using various analytical techniques like XRD, Raman, and XPS analysis. The morphology of the individual constitutions and composites was examined by TEM. Photoelectrochemical analysis showed that the composite nanostructures of black TiO2/WO3/rGO exhibited enhanced water splitting activity under visible light irradiation (0.83 mA cm−2 at 0 V). This enhancement was attributed mainly to the more efficient photoinduced charge (electron–hole) separation and transportation involved in the composite nanostructures.