Advanced interfacial engineering of oxygen-enriched Fe_xSn_1−xOSe nanostructures for efficient overall water splitting and flexible zinc-air batteries

The rational design of the highly active, durable, and cost-effective catalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is essential for next-generation water splitting systems and zinc-air batteries. Herein, a novel strategy is demonstrated to design iron tin oxyselenide (Fe_xSn_1−xOSe) with enriched oxygen vacancies through a simple and straightforward hydrothermal and subsequent selenization process. The optimal Fe_0.33Sn_0.67OSe catalyst exhibits superior ORR, OER, and HER performances due to the numerous electroactive sites and high synergistic effects. The water electrolyzer requires a small voltage of 1.490 V and incredible reversibility over 24 h. Most interestingly, the Fe_0.33Sn_0.67OSe air-cathode based flexible ZAB exhibits a high power density of 153.96 mW cm⁻² and ultralong cycle life for 400 h. This work opens a new strategy to establish highly active and durable multifunctional catalysts in next-generation energy conversion and storage systems.