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

A uniform dispersion of black TiO 2 nanoparticles and WO 3 nanorods on rGO nanosheets was assessed for its photoelectrochemical water splitting activity. A facile solution-based approach was employed to synthesize the black TiO 2 nanoparticles and WO 3 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-TiO 2 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 TiO 2 /WO 3 /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. Schematic diagram for the proposed mechanism of heterojunction photocatalysis for the hydrogen production. • Black TiO 2 /WO 3 /rGO nanocomposites were prepared as photoanode. • The bandgap energy of the composite was significantly narrowed to 1.76 eV. • Black TiO 2 /WO 3 /rGO nanocomposites exhibit enhanced visible-NIR light absorption. • The enhanced photocurrent density of 0.83 mA cm −2 at 0 V was achieved. • The enhancement is due to more efficient charge separation and transportation.