Interface engineering of iron sulfide/tungsten nitride heterostructure catalyst for boosting oxygen reduction activity

Herein, we demonstrate an ion migration approach for constructing iron sulfide/tungsten nitride heterostructure supported over carbon nanoboxes as an efficient and robust electrocatalyst toward the oxygen reduction reaction. Tungsten nitride decorated at iron sulfide induces the electron delocalization of iron sites for facilitating the electron/proton transfer into adsorbed oxygen molecules that is generally proposed as the rate-determining step over the sulfides. It also greatly promote the reversible Fe2+/3+ redox transition during catalysis that determines the durability performance. Therefore, the iron sulfide/tungsten nitride heterostructure catalyst shows much superior activity and long-term stability to pristine iron sulfide, as evidenced in the setups of rotating disk electrode and half-cell gas diffusion electrode. It is explored as an exceptional air cathode of rechargeable zinc-air battery that stably operates for over 140 h without the performance loss. This work offers a novel synthetic strategy for designing transition–metal nitride/sulfide heterostructure and provides an insight into optimized electron configuration via interface engineering.