Atomically Dispersed Dual-Metal ORR Catalyst with Hierarchical Porous Structure for Zn-Air Batteries.

Abstract

The metal-nitrogen-carbon (M-N-C)-based catalysts are promising to replace PGM (platinum group metal) to accelerate oxygen reduction reaction due to their excellent electrocatalytic performance. However, the inferior intrinsic activity and poor active site density confining further improvement in their performance. Modulating the electronic structure and reasonably designing the pore structure are widely acknowledged effective strategies to boost the activity of the M-N-C catalysts. However, it is a great challenge to form abundant pores to regulate the electronic structure via the facile method. Herein, a hierarchical, porous dual-atom catalyst FeNi-NPC-1000 has been architectured by the Na2CO3 template method and bimetallic doping modification strategy. Benefitting from the optimized pore and electronic structure, the as-prepared FeNi-NPC-1000 possesses a high specific surface area (1412.8 m2 g-1) and improved ORR activity (E1/2 = 0.877 V vs RHE), which is superior to that of Pt/C (E1/2 = 0.867 V vs RHE). With the evidence of AC-STEM, XAS, and DFT, the FeNi-N8-C moiety is proven to be the key active site to realize high-efficiency ORR catalysis. When assembled it as an air cathode of ZABs, FeNi-NPC-1000 displays superior discharge performance (Pmax = 367.1 mW cm-2) and a stable battery long-life. This article will provide a new strategy for designing dual-metal atomic catalysts applied in metal-air batteries.