Robust wrinkled MoS₂/N-C bifunctional electrocatalysts interfaced with single Fe atoms for wearable zinc-air batteries

The ability to create highly efficient and stable bifunctional electrocatalysts, capable of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the same electrolyte, represents an important endeavor toward high-performance zinc-air batteries (ZABs). Herein, we report a facile strategy for crafting wrinkled MoS₂/N-doped carbon core/shell nanospheres interfaced with single Fe atoms (denoted MoS₂@Fe-N-C) as superior ORR/OER bifunctional electrocatalysts for robust wearable ZABs with a high capacity and outstanding cycling stability. Specifically, the highly crumpled MoS₂ nanosphere core is wrapped with a layer of single-Fe-atom-impregnated, N-doped carbon shell (i.e., Fe-N-C shell with well-dispersed FeN₄ sites). Intriguingly, MoS₂@Fe-N-C nanospheres manifest an ORR half-wave potential of 0.84 V and an OER overpotential of 360 mV at 10 mA·cm⁻². More importantly, density functional theory calculations reveal the lowered energy barriers for both ORR and OER, accounting for marked enhanced catalytic performance of MoS₂@Fe-N-C nanospheres. Remarkably, wearable ZABs assembled by capitalizing on MoS₂@Fe-N-C nanospheres as an air electrode with an ultralow area loading (i.e., 0.25 mg·cm⁻²) display excellent stability against deformation, high special capacity (i.e., 442 mAh·g⁻¹_Zn), excellent power density (i.e., 78 mW·cm⁻²) and attractive cycling stability (e.g., 50 cycles at current density of 5 mA·cm⁻²). This study provides a platform to rationally design single-atom-interfaced core/shell bifunctional electrocatalysts for efficient metal-air batteries.