A pH-dependent microkinetic modeling guided synthesis of porous dual-atom catalysts for efficient oxygen reduction in Zn-air batteries

Abstract

The oxygen reduction reaction (ORR) plays a crucial role in diverse energy conversion devices, such as zinc-air batteries (ZABs). Highly-efficient screening, rational design and precise synthesis of active and stable ORR electrocatalysts will advance ZAB technology for practical applications but they remain very challenging. Herein, we utilized a pH-field coupled microkinetic model to identify Fe1Co1-N6 as the optimal dual-atom catalyst (DAC) for ORR in alkaline media. According to theoretical prediction, a Fe1Co1-N-C DAC with a hierarchically porous structure was synthesized by a hard-template method following a CO2 activation process. The prepared Fe1Co1-N-C DAC exhibits superior ORR activity and stability to the benchmark Pt/C catalyst. More impressively, the Fe1Co1-N-C based ZABs exhibit excellent performance including a high open-circuit voltage (1.51 V), a very high energy density (1079 W h kgZn−1), the best-ever rate capability (from 2 to 600 mA cm−2), and ultra-long ZAB lifespan (over 3600 h/7200 cycles under 5 mA cm−2). This work not only demonstrates that highly-efficient screening combined with rational design of DACs with optimal active sites and pore structures can boost their practical applications, but also presents a highly promising and effective way to synthesize different electrocatalysts for diverse applications.