Design and construction of bi-metal MOF-derived yolk–shell Ni2P/ZnP2 hollow microspheres for efficient electrocatalytic oxygen evolution

Abstract

It is highly challengeable to explore and design high-performance non-noble metal electrocatalysts for the oxygen evolution reaction (OER) towards highly efficient water electrolysis. Herein, we design and synthesize, for the first time, a novel cost-efficient electrocatalyst, i.e., hierarchical yolk–shell Ni₂P/ZnP₂ hollow microspheres (NZP HMSs), via a two-step strategy involving a solvothermal process and subsequent phosphatization. When utilized as a promising electrocatalyst for the OER, the yolk–shell NZP HMS specimen exhibits more exceptional OER performances than its solid Ni₂P counterpart, including a lower overpotential of 210 mV at 10 mA cm⁻², a smaller Tafel slope of 57.8 mV dec⁻¹ and more superior electrochemical stability in 1 M KOH. The superb electrocatalytic OER properties are attributed to the synergistic contributions from the Ni₂P/ZnP₂ hetero-interface at the nanoscale, favorable electronic conductivity and high electroactive surface area. More significantly, we strongly envision that this simple synthetic methodology can be highly versatile for other hierarchical yolk–shell hollow phosphides towards the OER and beyond.