Yttrium‐ and nitrogen‐doped NiCo phosphide nanosheets for high‐efficiency water electrolysis

Abstract Engineering high‐performance and low‐cost bifunctional catalysts for H₂ (hydrogen evolution reaction [HER]) and O₂ (oxygen evolution reaction [OER]) evolution under industrial electrocatalytic conditions remains challenging. Here, for the first time, we use the stronger electronegativity of a rare‐Earth yttrium ion (Y³⁺) to induce in situ NiCo‐layered double‐hydroxide nanosheets from NiCo foam (NCF) treated by a dielectric barrier discharge plasma NCF (PNCF), and then obtain nitrogen‐doped YNiCo phosphide (N‐YNiCoP/PNCF) after the phosphating process using radiofrequency plasma in nitrogen. The obtained N‐YNiCoP/PNCF has a large specific surface area, rich heterointerfaces, and an optimized electronic structure, inducing high electrocatalytic activity in HER (331 mV vs. 2000 mA cm⁻²) and OER (464 mV vs. 2000 mA cm⁻²) reactions in 1 M KOH electrolyte. X‐ray absorption spectroscopy and density functional theory quantum chemistry calculations reveal that the coordination number of CoNi decreased with the incorporation of Y atoms, which induce much shorter bonds of Ni and Co ions and promote long‐term stability of N‐YNiCoP in HER and OER under the simulated industrial conditions. Meanwhile, the CoN‐YP₅ heterointerface formed by plasma N‐doping is the active center for overall water splitting. This work expands the applications of rare‐Earth elements in engineering bifunctional electrocatalysts and provides a new avenue for designing high‐performance transition‐metal‐based catalysts in the renewable energy field.