Electrodeposited CoSe2 supported on BiVO4 as an efficient photoanode for the enhanced photoelectrochemical water oxidation†

Designing an efficient photoanode material for photoelectrochemical (PEC) water splitting is critical for clean and sustainable solar-driven hydrogen production. A material with great potential for the PEC water oxidation is bismuth vanadate (BiVO₄). In this study, a novel and efficient composite photoanode was fabricated by electrodepositing a film of CoSe₂ on BiVO₄ and employed for PEC water oxidation. The as-prepared CoSe₂/BiVO₄ photoanode exhibited a significantly enhanced PEC performance in the oxygen evolution reaction (OER), with a photocurrent density of 5.89 mA cm⁻² at 1.23 V vs. RHE, which was four times higher compared to the bare BiVO₄ photoanode (1.49 mA cm⁻²). The highest value of applied bias photon-to-current efficiency (ABPE) of CoSe₂/BiVO₄ (0.86%) was also 4.5 times higher than BiVO₄ (0.19%). Furthermore, compared to BiVO₄, the composite photoanode demonstrated an improved electrochemical stability, charge transfer kinetics in OER, and electrical conductivity. The remarkable enhancement observed in the PEC performance of the CoSe₂/BiVO₄ photoanode can be attributed to the suppressed electron–hole recombination and faster charge transfer kinetics at the electrode/electrolyte interface. The superior performance of CoSe₂/BiVO₄ makes it a promising photoanode material for the enhanced PEC water oxidation.