Heterostructured CoFe1.5Cr0.5S3O/COFs/BiVO4 photoanode boosts charge extraction for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting can convert the inexhaustible solar energy into green and storable H2 to tackle fossil crisis and meet carbon neutrality. BiVO4 is regarded as a promising photoanode owing to its superior visible light absorption, moderate redox potentials and well chemical stability, but suffering from the rapid recombination of charge carriers and sluggish interfacial water oxidation kinetics. Herein, a heterostructured CoFe1.5Cr0.5S3O/COFs/BiVO4 photoanode was fabricated to accelerate charge carriers′ separation and boost water oxidation. The spinel-type CoFe1.5Cr0.5S3O serving as the co-catalyst enabled to largely lower the overpotential of water oxidation, while COFs acting as an interlayer passivated the interfacial defect between CoFe1.5Cr0.5S3O and BiVO4. Benefiting from the collaboration of CoFe1.5Cr0.5S3O co-catalyst and COFs interlayer, heterostructured CoFe1.5Cr0.5S3O/COFs/BiVO4 photoanode featuring with a prominent charge extraction efficiency reached an impressive water oxidation photocurrent of 5.1 mA cm−2 at 1.23 V vs. RHE under AM 1.5 G irradiation, higher than that of pristine BiVO4, binary COFs/BiVO4 and CFCOS/BiVO4 photoanodes. This work demonstrated that heterostructured BiVO4-based photoanode with co-catalyst and interlayer enables to simultaneously enhance charge carrier utilization efficiency and optimize surface catalysis kinetics for efficient solar-to-fuel conversion.