Synergistic promotion effects of hierarchical NiS/neodymium–doped CoS₂ interfaces-supported NC for high-performance water-splitting and zinc–air batteries

Developing efficient and durable multifunctional catalysts is crucial to advance sustainable energy conversion technologies. Here, we introduce a rationally designed transition metal sulphide catalyst, NiS/Nd–CoS₂@NC, in which the sulphurisation process plays a crucial role in optimising the electrocatalytic properties of the neodymium–doped precursor. This tailored sulphide architecture significantly enhances the intrinsic activity and electronic structure, resulting in outstanding trifunctional performance for the HER, OER, and ORR. The NiS/Nd–CoS₂@NC material demonstrates a low overpotential of 38 mV for HER and 191 mV for OER at 10 mA cm⁻² in alkaline medium. The material also exhibits superior ORR activity, achieving a high half-wave potential of +0.84 V and a favoured four-electron reaction pathway. The two-electrode device based on NiS/Nd–CoS₂@NC_(−,+), requires a cell voltage of only 1.53 V to deliver 10 mA cm⁻² and maintains long-term operational stability over 70 h towards overall water splitting. Meanwhile, the zinc–air battery using the NiS/Nd–CoS₂@NC cathode delivers a high maximum power density of 177.12 mW cm⁻², together with remarkable long-term stability for a continuous operation for 1500 h at 10 mA cm⁻² with negligible voltage decay. This work reveals the critical role of rare-earth elements in tailoring transition metal sulphides for electrocatalytic applications and provides a promising route towards high-performance multifunctional catalysts for renewable energy conversion.