Immobilization of Fe3N nanoparticles within N-doped carbon nanosheet frameworks as a high-efficiency electrocatalyst for oxygen reduction reaction in Zn-air batteries

Abstract

Rational design and feasible synthesis of economical, efficient and durable electrocatalysts as alternatives to precious metal-based catalysts toward the oxygen reduction reaction (ORR) is extremely desirable for the advancement of future sustainable energy devices. Herein, we demonstrate a feasible hydrogel-bridged nitridation method to construct a 3D hierarchical carbon nanohybrid consisting of uniform Fe3N nanoparticles immobilized by N-doped carbon nanosheet frameworks (abbreviated as Fe3N@N–C). Lyophilization and subsequent nitridation treatment of the hydrogel formed by chitosan and K3[Fe(CN)6] result in the formation of Fe3N@N–C catalyst. The firm coupling of well-dispersed Fe3N nanoparticles with the carbon nanosheet frameworks confers the synthesized Fe3N@N–C catalyst with abundant Fe–N–C active sites, robust mechanical strength and improved reaction kinetics. Consequently, the Fe3N@N–C catalyst shows excellent ORR activity, superb stability and remarkable tolerance to methanol in alkaline condition, as compared with commercial Pt/C catalyst. Remarkably, when applied as an air cathode catalyst in a primary Zn-air battery, the Fe3N@N–C catalyst displays comparable performance to the commercial Pt/C catalyst with high power density and specific capacity. The proposed strategy in this work is anticipated to inspire the future design of cost-effective yet high-performance electrocatalysts for advanced electrochemical applications.