Upcycling Post‐Harvest Soybean Straw Into FeCo Alloy‐Embedded N, S Co‐Doped Carbon as Electrocatalysts for Rechargeable Zinc–Air Batteries

ABSTRACT

The sluggish kinetics of oxygen reduction and evolution reactions (ORR/OER) at air cathodes restrict the practical performance of rechargeable zinc–air batteries (ZABs), driving the urgent demand for low‐cost, robust non‐noble metal bifunctional electrocatalysts. Abundant agricultural soybean straw, featuring native porous frameworks and abundant oxygenated functional groups, represents a promising carbon substrate that facilitates electrolyte penetration and homogeneous immobilization of catalytic active sites. Herein, we report a facile ZnCl ₂ ‐assisted pyrolysis strategy to fabricate FeCo alloy nanoparticles embedded within N, S co‐doped biomass‐derived carbon (denoted FeCo@NSC‐900) via the high‐value upcycling of waste soybean straw. Enabled by the multi‐component synergistic effect between FeCo alloys, heteroatom coordination sites and porous carbon matrix, the as‐synthesized FeCo@NSC‐900 exhibited outstanding bifunctional electrocatalytic activity: it delivered an ORR half‐wave potential of 0.880 V versus reversible hydrogen electrode (RHE). When assembled as the air cathode of rechargeable ZABs, FeCo@NSC‐900 afforded a peak power density of 211.26 mW cm ⁻² and a specific capacity of 798.60 mAh g ⁻¹ at 10 mA cm ⁻² . More importantly, the assembled battery achieved remarkable cycling stability over 160 h. This study offers a sustainable design paradigm for converting waste agricultural biomass into bifunctional air electrodes.