Active‐Site Interactions in a Synergistic Porous Structured Fe Nanoparticle–Carbon Electrocatalyst for Enhanced Redox Reactions in Alkaline Zn–Air Batteries

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Abstract
In practical applications, zinc–air batteries (ZABs) require high‐performance, durable, and cost‐effective electrocatalysts for the critical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Here, we describe a reflux synthesis method of constructing a porous catalyst by introducing turmeric yellow into extremely porous bio‐carbon (PC) materials that contain iron nanoparticles (Fe NPs); these catalysts are known as Fe NPs@PC. These catalysts have become a significant substitute for high‐performance cathodes in ZABs because their electrochemical properties can improve ORR performance. In addition to enhancing conductivity, the OER/ORR bifunctional active sites must be balanced by optimizing the FeC and FeFe interactions within the active site. X‐ray absorption analysis and density functional theory confirmed that strong iron‐carbon interactions promote OER ( η 10 = 320 mV) and ORR ( E 1/2 = 0.786 V) activity and exhibit a smaller potential gap of 0.764 V of Fe NPs@PC‐700 catalyst. The impact of this redox activity enhances the high‐power density (219 mW cm −2 ) and long‐term charge–discharge cycle stability (85 h@3 mA cm −2 ) of ZABs. This work charts a viable route for the assembly of practical ZABs by regulating bifunctional electrocatalysts via appropriate modification of active sites.

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