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

## TL;DR

This paper introduces a new electrocatalyst made of iron nanoparticles and bio-carbon to improve the performance of zinc-air batteries.

## Contribution

A novel synthesis method using turmeric yellow to create a porous Fe NPs@PC catalyst with enhanced ORR/OER activity is presented.

## Key findings

- Fe NPs@PC-700 catalyst achieves an OER η10 of 320 mV and ORR E1/2 of 0.786 V.
- The catalyst shows a potential gap of 0.764 V and a high power density of 219 mW cm−2.
- The catalyst enables long-term stability with 85 hours of charge-discharge cycles at 3 mA cm−2.

## 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.

The synthesis of environmentally benign bio‐carbon‐supported metal nanoparticles and a brief study of the iron–carbon interaction enhance the redox activity of oxygen evolution reaction and oxygen evolution reaction techniques in Zn–air batteries.© 2026 WILEY‐VCH GmbH