Recent advances and perspectives on iron-based photocatalysts

Global warming caused by the overuse of non-renewable fossil energy has resulted in serious global energy and environmental issues, including resource scarcity, melting glaciers, fires and locust plague. Accordingly, the design and development of high-performance, earth-abundant, non-toxic and cost-effective photocatalysts to realize solar energy conversion, organic pollutant degradation, carbon dioxide reduction and hydrogen production are considered the most effective methods to resolve both the energy and environmental crises. Iron is the second most abundant metal (5.0%) on Earth and has been extensively introduced in photocatalytic reactions to improve the generation, separation and utilization efficiency of charge carriers owing to its suitable band gap, redox position and low redox overpotential. Thus, iron-based photocatalysts have gained prominence as viable candidates owing to their abundance, eco-friendliness and exceptional photocatalytic performance. This critical review delves into the recent advances in the design of iron-based nanomaterials. Initially, we present an overview of the recent advancements in the design of iron-based heterojunctions (type II, Z-scheme, and S-scheme heterojunctions). Subsequently, we thoroughly summarize the application of iron-based photocatalysts in oxygen and hydrogen evolution reactions, carbon dioxide conversion and nitrogen fixation. Finally, we outline the future perspectives for the improvement of next-generation iron-based photocatalysts. Iron based nanomaterials/complexes/alloys/MOFs have been discussed for CO2 reduction, N2 fixation, pollutants degradation and OER/HER via type II, Z-scheme and S-scheme heterojunctions.