Interfacial engineering of Bi-based heterojunction for boosting photocatalytic nitrogen fixation: a perspective review

Photocatalytic ammonia synthesis, which leverages solar energy to convert nitrogen and water into ammonia, presents a sustainable and environmentally friendly alternative to the energy-intensive Haber-Bosch process. However, the effective activation of the particularly strong N≡N bond remains a significant challenge. Bismuth (Bi)-based materials have been identified as promising photocatalysts due to their strong absorption of visible light, high nitrogen adsorption capacity, and low toxicity. To further improve their photocatalytic performance, extensive research has been directed toward the design of Bi-based heterojunctions. This review highlights the essential and often decisive influence of heterojunction interface engineering in enhancing photocatalytic nitrogen fixation performance. Unlike traditional heterojunction construction, precise interfacial engineering - including the development of built-in electric fields, chemical bonds at the interface, atomic-scale charge transfer pathways, and defect-mediated active sites can fundamentally modulate charge separation, promote N2 adsorption and activation, and enhance structural stability. A systematic summary of recent advancements in various Bi-based heterojunctions (e.g., Type II, Z-scheme, and S-scheme) is provided, with particular emphasis on how interface design governs reaction mechanisms and catalytic efficiency. Finally, current challenges and future perspectives are discussed to inform the rational design of high-performance catalysts and to further the development of photocatalytic nitrogen fixation through interface-focused strategies.