Bifacial Modulation of Carrier Transport in BiVO4 Photoanode for Stable Photoelectrochemical Water Splitting via Interface Engineering

Monoclinic bismuth vanadate photoanodes promise high efficiency-to-cost ratios for photoelectrochemical (PEC) water splitting owing to their suitable band structure and ease of synthesis. However, inadequate charge separation and sluggish oxidation kinetics remain a fundamental challenge. This study investigates bifacially interface engineered BiVO4 photoanodes by considering a seed-layer and NiOOH oxygen evolution catalyst (OEC) over-layer to regulate the charge carrier transport and improve the overall PEC water-splitting performance. The modification of the BiVO4/FTO interface stimulates electron flow towards fluorine-doped tin oxide (FTO) and a NiOOH over-layer improves the facile hole transfer from BiVO4 to the electrolyte. Compared to the moderate photocurrent density of a bare BiVO4 photoanode (1.5 mA cm(-2)), the interface-engineered Seed_BiVO4_NiOOH photoanode shows a remarkably high (approximate to 3.4 times higher) photocurrent density of 5.10 mA cm(-2) at 1.23 V vs reversible hydrogen electrode with impressive long-term stability over 9 h under illumination. The optimally interface engineered Seed_BiVO4_NiOOH photoanode shows an excellent photoconversion efficiency (1.83%), with significant improvement in bulk charge separation efficiency. This work presents a promising strategy for the development of a highly stable PEC water-splitting device and eliminates the intrinsic material shortcomings of the bare BiVO4 photoanode by modulating the carrier transport via bifacial interface engineering.