LaS/CoS2 Heterojunction Nanorods for Enhanced Bifunctional Oxygen Catalysis in Zinc–Air Batteries

Abstract

Conventional rechargeable zinc–air batteries (RZABs) are largely hindered by the sluggish reaction kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air cathode. Therefore, the rational design of highly active bifunctional electrocatalysts is crucial for advancing performance of the energy storage system. In this study, we synthesized uniform porous LaS/CoS₂ heterojunction nanorods, in which LaS was introduced into transition metal sulfide to construct abundant sulfur vacancies and well-defined heterointerfaces. This not only effectively regulated the electronic structure of the LaS/CoS₂ heterojunctions but also significantly enhanced their bifunctional catalytic activity, which possessed an ORR/OER voltage gap of as low as 0.72 V. The RZAB assembled with LaS/CoS₂ as an air cathode had a high peak power density of ca. 190 mW cm^–2, stable open-circuit voltage of ca. 1.54 V, and remarkable specific capacity of ca. 801.7 mAh g_Zn^–1. The RZAB device maintained stable charge–discharge cycling over 480 h with negligible performance degradation, surpassing the performance of conventional Pt/C and RuO₂-based counterparts across multiple evaluation metrics. This work elucidated the synergistic effect between sulfur vacancies and heterojunction interfaces and mechanistic insight into their role in promoting electrocatalytic activity. These findings provide a promising strategy for the design of efficient and durable bifunctional catalysts for next-generation metal–air batteries.