In-Situ Noble Fabrication of Bi₂S₃/BiVO₄ Hybrid Nanostructure through a Photoelectrochemical Transformation Process for Solar Hydrogen Production

Here, we establish a methodology and phenomena for systematically assessing the photoelectrochemical transformation of the BiVO₄ to Bi₂S₃/BiVO₄ hybrid heterostructure during in-situ solar hydrogen generation. The photoelectrochemical transformation involves a facile anion exchange process by reacting BiVO₄ photoelectrodes with Na₂S/Na₂SO₃ electrolyte. X-ray photoelectron spectroscopy and transmission electron microscopy analyses confirmed the successful transformation of BiVO₄ into the Bi₂S₃/BiVO₄ nanostructure matrix. The photocurrent density of the ABV3 photoelectrode is optimized to be 3.3 mA cm^-2 with hydrogen generation activity (∼417 μmol cm^-2 h^-1) under simulated sunlight at 0.67 V versus reversible hydrogen electrode (RHE). The impacts of other factors such as crystal structure, enhancing light harvesting, and increasing electron-hole separation on the photoelectrochemical performance and stability of Bi₂S₃/BiVO₄ hybrid photoanodes are highlighted. A model based on the photoelectrochemical transformation is also proposed to explain the growth and charge transport phenomenon in Bi₂S₃/BiVO₄ hybrid nanostructured photoanodes. These findings are expected to shed light on further understanding and design of a novel strategy of engineering electronic band structure through photoelectrochemical transformation, which plays a key role in the enhanced performance of hybrid nanostructures in the fields of energy conversion.