Protein-mediated synthesis of iron single atom electrocatalyst with highly accessible active sites for enhanced pH-universal oxygen reduction

Facile synthesis of highly efficient non-precious metal electrocatalysts is intriguing as these catalysts are used in the oxygen reduction reaction (ORR). Herein, we describe an effective protein-mediated approach to access atomically dispersed iron electrocatalyst (Fe SAs/NC) with enhanced accessible metal active sites. This Fe catalyst achieves an exceptional ORR activity in the pH-universal range, especially in alkaline and acid electrolytes with half-wave potentials of 0.93 and 0.84 V (vs RHE), respectively. The unique electronic structure of Fe sites with enhanced electron/proton transportation ability contributes to the optimized adsorption/desorption of oxygen intermediates. In addition, it shows robust durability and excellent tolerance to methanol crossover in pH-universal media. Impressively, it displays encouraging performance when employed in a zinc-air battery, demonstrating a peak power density of 275.1 mW cm−2 and a specific capacity of 753.8 mAh g−1. The extremely long-term operational stability of more than 250 h further provides significant potential for its application.