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

Abstract

• An ion migration approach is reported for preparing the Fe 1-x S/WN heterostructure. • The electron depletion of iron centers caused by WN promotes the O 2 protonation. • WN component promotes the reversible Fe 2+/3+ redox couple during catalysis. • An exceptional durability is demonstrated in the setups of RDE and half-cell GDL. • Zn-air battery driven by Fe 1-x S/WN delivers a stable and outstanding performance. 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 Fe 2+/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.