Preparation of defect-rich Ni3P-NiB-FeB heterostructure as efficient bifunctional electrocatalyst for overall water splitting

Designing transition metal-based heterointerfaces and creating defects are identified as prospective strategies for substituting the expensive noble metal-based catalysts for realizing efficient water electrocatalysis to alleviate the energy and environmental crisis. Herein, pleated sheet-like NiP3-NiB-FeB heterostructure nanoarrays with three-phase heterojunctions and luxuriant defects were developed and grown in-situ on carbon cloth as effective self-supported bifunctional electrocatalysts for water-splitting by a facile one-step solution titration method. As expected, the Ni3P-NiB-FeB reveals remarkable electrocatalytic performance, requiring only 134 mV and 275 mV overpotentials to achieve the current density of 10 mA cm−2 for HER and 100 mA cm−2 for OER, respectively, whose performance exceeds most transition metal-based catalysts in previous reports. More encouragingly, the electrolyzer with Ni3P-NiB-FeB as a working electrode can attain a current density of 10 mA cm−2 at a low voltage of 1.63 V accompanied by a long cycle stability of at least 36 h. The large specific surface area, abundant heterogeneous phase interfaces, and rich defective sites jointly contribute to the exposure of more active sites, regulation of the regional electron density, and promotion of the electrical conductivity, while the introduction of electronegativity P and electron-deficient B also impart Ni3P-NiB-FeB with strong electronic interactions and fast charge transfer, thus endowing Ni3P-NiB-FeB with excellent catalytic activity. This work opens up new opportunities in multi-phase heterointerfaces and defects engineering of transition metal-based borides and phosphides as efficient multifunctional electrocatalysts for practical water splitting.