Electronic Modulation via Dual-Phase Coupling of CoNi Alloy and NiCo2S4 on N, S-Co-Doped Porous Carbon Spheres for High-Performance Rechargeable Zn-Air Batteries.

Abstract

The development of efficient bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries remains constrained by the trade-off between activity and durability. Here, we break this bottleneck by rationally constructing a CoNi alloy/NiCo2S4 dual-phase heterostructure embedded in N, S-codoped porous carbon spheres (CoNi/NiCo2S4@NSPCs) via controlled partial sulfidation. Crucially, this mild process partially converts CoNi nanoparticles into NiCo2S4, preserving the highly conductive alloy phase while creating intimately coupled metal/sulfide heterointerfaces. The resulting architecture synergistically combines alloy conductivity, abundant sulfide active sites, and efficient mass transport through the porous carbon framework. Density functional theory(DFT) calculations reveal that interfacial electronic redistribution optimizes oxygen-intermediate adsorption, thereby accelerating both oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) kinetics. Consequently, the catalyst achieves outstanding bifunctional performance with a low overpotential gap and remarkable operational stability. When employed as an air-cathode catalyst, CoNi/NiCo2S4@NSPCs enables a flexible Zn-air battery (FZAB) with an open-circuit voltage of 1.44 V and a high specific capacity of 656.77 mAh gZn -1, while maintaining stable charge-discharge operation under bending and over 100 h of cycling. These metrics surpass most state-of-the-art bifunctional oxygen electrocatalysts. This work establishes partial sulfidation as a general strategy for engineering dual-phase nonprecious metal electrocatalysts for practical flexible energy applications.

Abstract as supplied by the indexing source. © the authors / publisher.