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 kg_Zn⁻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.