A plasma-triggered N–Co–O–Fe motif in Co(OH)2 for efficient electrocatalytic oxygen evolution

Abstract

The rational design and synthesis of oxygen evolution reaction (OER) electrocatalysts remain critical challenges for water electrolysis in hydrogen production. This study used a strategy to activate the lattice oxygen mechanism (LOM) pathway in Co(OH)₂ through uniform co-doping with metallic Fe and nonmetallic N, thereby forming N–Co–O–Fe moieties at the Fe,N–Co(OH)_x interface. The synergistic effects of Fe and N accelerated electron redistribution from Co to Fe atoms, promoting the formation of active high-valent Co(IV) and stimulating lattice oxygen activation. The intrinsic activity of Co(OH)₂ was enhanced. The as-synthesized Fe,N–Co(OH)_x exhibited exceptional performance, with high mass activity (1705 A g_metal⁻¹) and turnover frequency (2.521  s⁻¹), surpassing those of W,N–Co(OH)_x by 80.4 and 57 times (21.2 A g_metal⁻¹ and 0.044  s⁻¹), respectively. In situ spectroscopy and ¹⁸O isotope-labeled differential electrochemical mass spectrometry confirmed that Fe,N–Co(OH)_x achieved direct intramolecular lattice oxygen coupling via the LOM pathway during the OER process. Density functional theory calculations revealed that Fe and N co-doping synergistically modulated the d-band center of Co in Fe,N–Co(OH)_x, reducing the energy barrier for OO* desorption to form oxygen vacancies. The proposed method facilitated the preparation of heteroatom-doped hydroxide catalysts to activate the LOM pathway in the OER by co-regulating multiple defects.