Durability Meets Performance: A LaCoO3–MoS2 Composite for Electrochemical Overall Water Splitting

Designing bifunctional catalysts for green hydrogen production is the key to realizing efficient and scalable water electrolysis. While bifunctional electrocatalysts can reduce the system design complexity and lower the operational cost by catalyzing both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) within the same electrolyte, incorporating dual active sites into one framework often involves trade-offs between activity and durability. This work reports a chemically integrated LaCoO₃–MoS₂ (LCM) composite as a noble-metal-free bifunctional catalyst for alkaline water splitting. Among a series of LaCoO₃–MoS₂ composites synthesized, the composition LCM-100 exhibits the highest electrochemical performance. Unlike physically mixed counterparts with weak interfacial contact and poor charge transport, the hierarchical architecture of LCM-100, featuring edge-exposed MoS₂ nanosheets chemically anchored onto a redox-active, structurally stable LaCoO₃ support, enables strong interfacial coupling and efficient electron transfer. This leads to superior electrocatalytic activity toward both the HER (236 mV) and the OER (1.64 V vs reversible hydrogen electrode, RHE) at 10 mA cm^–2 in alkaline media. In a full water-splitting electrolyzer, LCM-100 coated on a neutral carbon paper substrate initially delivers a cell voltage of 1.70 V_RHE at 10 mA cm^–2, which improves to 1.67 V_RHE after chronopotentiometric activation and exhibits impressive stability at 250 mA cm^–2 for 100 h. These findings underscore the effectiveness of chemical integration in designing noble-metal-free bifunctional catalysts for practical water-splitting applications.