Interfacial coupling of Ce-CoSe nanoneedle arrays with MXene for efficient overall water splitting.

Designing highly effective, low-cost bifunctional electrocatalysts without noble metals for overall water splitting remains a significant challenge. In this work, interfacial coupling of Ce-doped CoSe nanoneedle arrays with MXene (Ce-CoSe/MXene) is developed via the facile hydrothermal and selenization methods. The extensive specific surface area and favorable hydrophilicity of TiAlC, combined with the optimized electronic structure and abundant active sites from Ce-doping and selenization, contribute to the exceptional bifunctional electrocatalytic performance of the Ce-CoSe/MXene electrode. Specifically, this heterostructure achieves a low hydrogen evolution reaction (HER) overpotential of 34 mV at 10 mA cm, an oxygen evolution reaction (OER) overpotential of 279 mV at 100 mA cm, and an overall water splitting (OWS) potential as low as 1.45 V at 10 mA cm. In-situ Raman spectroscopy reveals that surface reconstruction would improve catalytic activity and stability. Theoretical calculations indicate that the Ce-CoSe/MXene can improve the adsorption of intermediates and facilitate HER/OER process by lowering the kinetic barrier, thereby enhancing electrocatalytic activity. This research marks a substantial advancement in the development of low-cost, efficient electrocatalysts for overall water splitting.