Engineering interfacial band bending over bismuth vanadate/carbon nitride by work function regulation for efficient solar-driven water splitting

Nature-inspired artificial Z-scheme photocatalyst offers great promise in solar overall water splitting, but its rational design, construction and interfacial charge transfer mechanism remain ambiguous. Here, we design an approach of engineering interfacial band bending via work function regulation, which realizes directional charge transfer at interface and affords direct Z-scheme pathway. Taking BiVO4 as prototype, its oxygen vacancy concentration is reduced by slowing down the crystallization rate, thereby changing the work function from smaller to larger than that of polymeric carbon nitride (PCN). Consequently, the photoinduced charge transfer pathway of BiVO4/PCN is switched from type-II to Z-scheme as evidenced by synchronous illuminated X-ray photoelectron spectroscopy (XPS) and femtosecond transient absorption spectroscopy. Specifically, the direct Z-scheme BiVO4/PCN shows superior photocatalytic performance in water splitting. This work provides deep insights and guidelines to constructing heterojunction photocatalysts for solar utilization.