Engineering high-performance BiVO4 homo- and heterojunction Photoanodes for solar-driven Photoelectrochemical water splitting applications

Green hydrogen has secured its foothold as the most promising fossil fuel-alternative, with over half a century of intensive research focusing on the development of photoelectrochemical (PEC) water splitting system. The higher overpotential required for an oxygen evolution reaction necessitates the development of a highly performing photoanode as compared to photocathode, as it reduces the externally applied bias needed for a water splitting reaction. Bismuth vanadate (BiVO₄) has emerged as an immensely potential candidate, due to its favorable bandgap, earth abundance and good chemical stability. However, the rapid charge carrier recombination and sluggish oxygen evolution reaction have severely undermined BiVO₄'s water splitting performance. To fully unleash its potential, modifications are necessary, with the formation of homo- and heterojunctions showing significant contributions in enhancing PEC water oxidation. This review comprehensively discusses and highlights the strategies for constructing homo- and heterojunction of BiVO₄, as well as the insights in boosting the solar water splitting performance. The review on the formation of homojunction is classified into doping, facet and morphology-engineered homojunction, while the formation of heterojunction is classified based on the functional properties, n-n, p-n and Z-scheme heterojunction. The development of an unbiased solar-driven PEC water splitting system based on heterostructured BiVO₄ is also thoroughly discussed, along with perspective on current and future research related to PEC water oxidation. This review aims to provide an extensive coverage of research on engineering homo- and heterojunctions for BiVO₄-based photoanode, which will also serve as a reference for other semiconductors in enhancing their various PEC applications.