P-Doped g-C₃N₄ Nanosheet-Modified BiVO₄ Hybrid Nanostructure as an Efficient Visible Light-Driven Water Splitting Photoanode

Here, a solution combustion method was employed to construct a photoanode based on bismuth vanadate (BV) composition. To curtail the fast charge recombination, phosphorus-doped g-C3N4 nanosheets (PCNS) in combination with BV are considered a potential approach. The prepared solution combustion facilitated the formation of a BiVO4-PCNS (BV-PCNS) hybrid photoanode with worm-like morphology with a simple setup. The weight ratio of PCNS/BiVO4 and the loading volume/cm2 were optimized to determine the most efficient photoanode. The highest photocurrent density of 0.5 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE) under 1 sun illumination was achieved for the hybrid nanostructure at 2 wt % of PCNS/BiVO4 and 50 μL loading volume/cm2 (BV-PCNS2-50), which is fivefold higher than that of the BV control sample. It was found that the presence of PCNS resulted in the formation of mid-gap states to enhance the visible light activity of BV-PCNS. A possible charge transfer mechanism is proposed under photoirradiation to show how the optimized deposition parameters influence the reduction of the electron–hole recombination rate of the photoanode and thus improve its photoelectrochemical water splitting performance. Density functional theory calculations were also performed to find the band alignment type formed across the BV/PCNS interface and to suggest the charge transfer mechanism in the BV/PCNS interface.