Sandwich-like structured NiSe₂/Ni₂P@FeP interface nanosheets with rich defects for efficient electrocatalytic water splitting

Constructing well-defined nanointerfaces is vital to enhance the catalytic performances through electronic coupling effects from different components. However, it is still a challenge to construct metal selenides-based interfacial nanomaterials with satisfactory oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances for overall water splitting. Herein, sandwich-like structured NiSe₂/Ni₂P@FeP nanosheet arrays are rationally constructed, which starts from NiSe₂ arrays directly on carbon cloth as backbones, followed by coating FeP nanoparticles on the backbones through the phosphorization process. Further, abundant nanointerfaces with rich defects and disordered structure are constructed during the phosphorization process, which can boost the charge transfer rate and provide rich electroactive sites. Consequently, as-synthesized NiSe₂/Ni₂P@FeP nanosheet arrays exhibit good HER and OER performances with small overpotentials, low Tafel slopes and good stability. Further, the overall water splitting device built by NiSe₂/Ni₂P@FeP exhibits a voltage of 1.554 V to attain 10 mA cm⁻². Our current work may provide some new insights on rationally constructing nanointerfaces with rich defects to boost the catalytic performances for overall water splitting.