Enhanced charge carrier separation and stable photoelectrochemical water splitting via a high-performance BiVO₄/BiOBr Type-II heterojunction

The development of an ideal photoanode that exhibits broad light absorption, efficient photogenerated carrier separation, and superior transmission efficiency remains a pivotal challenge in enhancing the sluggish photoelectrochemical (PEC) water splitting reaction. Here, we present an efficacious strategy to bolster the PEC performance of oxygen evolution by fabricating a BiVO₄/BiOBr heterojunction through a combined electrochemical deposition-calcination approach and the successive ionic layer adsorption and reaction (SILAR) method. The band structure of BiOBr is optimally aligned with BiVO₄, enabling the heterojunction to significantly enhance the separation efficiency of photogenerated charges and accelerate the kinetics of PEC water oxidation. Under simulated sunlight irradiation, the BiVO₄/BiOBr heterojunction exhibits a remarkable photocurrent density of 2.69 mA/cm² at 1.23 V vs. reversible hydrogen electrode (RHE), surpassing the performance of bare BiVO₄ film (0.46 mA/cm² at 1.23 V vs. RHE) and demonstrating exceptional stability. This work offers novel insights into the rational design and fabrication of solar-driven PEC water splitting photoanodes.