Synergistic Enhancement of β-NiOOH Electrocatalytic Oxygen Evolution Reaction Performance through Transition Metal Atom Doping and Vacancy Modulating

Abstract

Layered β-NiOOH exhibits potential as a non-precious electrocatalyst for the oxygen evolution reaction (OER) owing to its tunable electronic structure through doping and defect modulating. However, the mechanistic relationship between the potential-determining step (PDS) energy barrier and the demand for modulating the electronic structure of the active center remains unresolved. This work systematically investigates the effects of compositional tuning (Cr, Mn, Fe, Co, Cu, Zn, Rh), vacancy modulation (H, O, OH), and their synergistic effect on the OER properties of β-NiOOH using density-functional theory calculations. Results reveal that β-NiOOH achieves superior OER performance through the lattice oxygen mechanism with OH as active sites, where the PDS (*O→*OOH, 0.98 V) suggests weak OHˉ adsorption and an electron-rich active center. Notably, Cu-doping combined with H-vacancy synergistically reduces the overpotential to 0.53 V. This enhancement is attributed to the co-regulation of dopant-vacancy. The d band center moved away from the Fermi level, doping-induced spin polarization promoting d-p hybridization, and increased Bader charge of *OOH from 0.67 e (β-NiOOH) to 1.29 e (Cu_IV-NiOOH-V_H-3), collectively facilitating electron escape from the active site, thereby enhancing OHˉ adsorption and lowering energy barriers. Additionally, the descriptor ($\psi =(\Delta V_{TM}^3+\Delta I_1)/\Delta \chi$$\psi =(\Delta V_{TM}^3+\Delta I_1)/\Delta \chi$) for the compositional modulation of β-NiOOH was established, exhibiting strong correlations with valence electron count difference (ΔV_TM), first ionization energy difference (ΔI₁), and electronegativity difference (Δχ) between dopants and Ni. Fitting result demonstrates a significant linear relationship between descriptor and OER overpotential variation (Δη, $\Delta \eta =-1.20\psi +0.24$$\Delta \eta =-1.20\psi +0.24$, R² = 0.92). This work offers practical and theoretical guidance for the development of high-performance OER electrocatalysts.