Light-assisted heterojunction cathode catalysts for zinc-air batteries

Rechargeable zinc-air batteries (ZABs) combine high theoretical energy density with inherent safety, low cost, and environmental compatibility. However, the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics at the air cathode limit energy efficiency and cycle life. Light-assisted heterojunction cathode catalysts, which integrate solar-energy conversion with oxygen electrocatalysis, represent a promising paradigm for enhancing the performance of ZABs. At heterojunction interfaces, band alignment, built-in electric fields, and electronic coupling promote the separation and transport of photogenerated charge carriers. These interfacial effects regulate the electronic structure of active sites and optimize the adsorption of oxygen-containing intermediates. Coupled photoelectric and photothermal effects can further accelerate interfacial reaction kinetics. This review examines operating principles, synergistic mechanisms, structural design strategies, characterization methods, and battery applications of light-assisted heterojunction cathode catalysts. We focus on organic semiconductors, carbon nitride, metal oxides, metal sulfides and phosphides, carbon-based materials, and emerging heterojunction systems. We then assess interfacial stability, light-use efficiency, mechanistic interpretation, standardized evaluation, and scalable fabrication. Finally, we outline priorities for designing efficient and stable light-assisted air cathodes.