Lattice-strained and ultra stable non-noble metal electrocatalysts for overall water splitting

Endeavors to curb the advanced, cost-efficient and ultra stable electrocatalysts for electrochemical water splitting is critically important for energy conversion. However, their limited electrocatalytic behavior caused by large particles (> 10 nm) has leaded to decreased active surface and interaction with the supporting matrix. Herein, we designed a three-dimensional networked multi-metallic phosphides nanosheet arrays in situ grown on nickel foam (NiCoP-Ni2P/NF), within ultrafine nanoparticles (ca. 2.4 nm) evenly distributed on the skeleton, and the lattice of NiCoP is tensilely strained and contains rich phosphorous vacancies that induce localized compressive strain. Combining experimental investigation and theory calculations on hydrogen/oxygen evolution reaction (HER/OER), the as-established NiCoP-Ni2P/NF electrodes realize superior electrocatalytic performance is attributed to the strain effect, that is, tensile strain enhances OER while compressive strain facilitates HER. Moreover, the elaborately fabricated NiCoP-Ni2P/NF electrode can be cycled over 300 and 30 hours for hydrogen and oxygen evolution reactions at 10 mA cm–2, respectively. The concept of lattice strain couples with phosphorous vacancies imposes the rational design of active and ultra stable non-noble metal electrocatalysts for sustainable hydrogen production.