Advances in Ta₃N₅-Based Photoanodes for Photoelectrochemical Hydrogen Production and Beyond

Photoelectrochemical (PEC) water splitting has garnered significant attention as a highly promising and environmentally sustainable route for direct solar-to-hydrogen conversion. Nevertheless, its practical application hinges critically on highly efficient and stable photoanode materials. Tantalum nitride (Ta₃N₅), an n-type semiconductor featuring an ideal bandgap and suitable energy band edges for water splitting, has emerged as a prominent candidate for PEC hydrogen generation. In this review, recent progress in Ta₃N₅-based photoanodes for solar energy conversion is comprehensively summarized. It begins with an overview of basic properties of Ta₃N₅, with an emphasis on its advantages and key challenges for solar water splitting. Next, the main fabrication methods for Ta₃N₅ film photoanodes are introduced. Highlighted are the effective performance enhancement strategies via improving light absorption, charge separation, and surface reaction kinetics. Furthermore, the development of Ta₃N₅-based PEC tandem cells for unassisted overall water splitting is discussed. Beyond hydrogen production, their emerging applications for the coproduction of high-value-added chemicals and other hydrocarbon fuels are also presented. Finally, the ongoing challenges and future prospects of Ta₃N₅ photoanodes for solar fuel production are discussed. It is anticipated that this comprehensive review can provide an instructive guideline for the rational design of high-performance Ta₃N₅-based photoanodes toward efficient solar energy conversion and storage.