Green Hydrogen Production via Photoelectrochemical Water Splitting with BiVO₄/WO₃ Heterojunction Photoanodes

Abstract

Photoelectrochemical (PEC) water splitting offers a direct route to green hydrogen production using solar energy, but practical photoanodes suffer from poor charge separation and limited photostability. We report a BiVO₄/WO₃ type-II heterojunction photoanode fabricated by pulsed laser deposition and post-annealing, achieving a photocurrent density of 4.82 mA/cm² at 1.23 V vs. RHE under AM 1.5G illumination — a 2.3× improvement over bare BiVO₄. Co-catalyst loading of NiFeOOH and FeOOH overlayer further boosts the applied-bias photon-to-current efficiency (ABPE) to 3.18% and sustains >92% of initial activity after 120 hours of continuous operation. In situ spectroscopy confirms that the WO₃ underlayer promotes hole extraction and suppresses surface recombination at the BiVO₄/electrolyte interface.