A Core/Shell Bi₂S₃/BiVO₄ Nanoarchitecture for Efficient Photoelectrochemical Water Oxidation

The construction of nanostructured heterostructure is a potent strategy for achieving high-performance photoelectrochemical (PEC) water splitting. Among these, constructing BiVO₄-based heterostructure stands out as a promising method for optimizing light-harvesting efficiency and reducing severe charge recombination. Herein, we present a novel approach to fabricate a type II heterostructure of core/shell Bi₂S₃/BiVO₄ using electrolytic deposition and successive ionic layer adsorption and reaction (SILAR) methods. We identify the type II heterostructure and the difference in fermi energy using UV-Vis spectroscopy, X-ray photoelectron spectroscopy, and PEC measurements. This redistribution of charges due to the fermi energy difference induces an interfacial built-in electric field from BiVO₄ to Bi₂S₃, reinforcing the photogenerated hole transfer kinetics from BiVO₄ to Bi₂S₃. The Bi₂S₃/BiVO₄ heterostructure exhibits a superior photocurrent (6.0 mA cm^-2), enhanced charge separation efficiency (85 %), and higher open-circuit photovoltage (350 mV). Additionally, the heterostructure displays a prolonged average lifetime of charge (1.63 ns), verifying this heterojunction could boost interfacial carriers' migration via an additional nonradiative quenching pathway. Furthermore, the lower photoluminescence (PL) intensity demonstrates the interfacial built-in electric field is beneficial for boosting charge migration.