Oxygen evolution reaction (OER) is an obstacle to the electrocatalytic water splitting due to its unique four-proton-and-electron-transfer reaction process. Many methods, such as engineering heterostructure and introducing oxygen vacancy, have been used to improve the catalytic performance of electrocatalysts for OER. Herein, the above two kinds of regulation are simultaneously realized in a catalyst by using unique ion irradiation technology. A nanosheet structured NiO/NiFe₂O₄ heterostructure with rich oxygen vacancies converted from nickel–iron layered double hydroxides by Ar⁺ ions irradiation shows significant enhancement in both OER and hydrogen evolution reaction performance. Density functional theory (DFT) calculations reveal that the construction of NiO/NiFe₂O₄ can optimize the free energy of O^* to OOH^* process during OER reaction. The oxygen vacancy-rich NiO/NiFe₂O₄ nanosheets have an overpotential of 279 mV at 10 mA cm⁻² and a low Tafel slope of 42 mV dec⁻¹. Moreover, this NiO/NiFe₂O₄ electrode shows an excellent long-term stability at 100 mA cm⁻² for 450 h. The synergetic effects between NiO and NiFe₂O₄ make NiO/NiFe₂O₄ heterostructure have high conductivity and fast charge transfer, abundant active sites, and high catalytic reactivity, contributing to its excellent performance.

中文翻译：

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用于增强电催化水分解的离子辐照诱导富氧 NiO/NiFe2O4 异质结构

析氧反应 (OER) 由于其独特的四质子和电子转移反应过程而成为电催化水分解的障碍。许多方法，如工程异质结构和引入氧空位，已被用于提高 OER 电催化剂的催化性能。在此，上述两种调节是通过独特的离子辐照技术在催化剂中同时实现的。具有富氧空位的纳米片结构 NiO/NiFe ₂ O ₄异质结构，通过 Ar ⁺从镍铁层状双氢氧化物转化而来离子辐照显示出 OER 和析氢反应性能的显着增强。密度泛函理论（DFT）计算表明，NiO/NiFe ₂ O ₄的构建可以优化OER反应过程中O ^*到OOH ^*过程的自由能。富含氧空位的NiO/NiFe ₂ O ₄纳米片在10 mA cm ^{-2 下}具有279 mV的过电位和42 mV dec ^-1的低Tafel斜率。此外，该 NiO/NiFe ₂ O ₄电极在 100 mA cm ^{-2 下}表现出优异的长期稳定性，持续 450 小时。NiO与NiFe ₂的协同作用O ₄使NiO/NiFe ₂ O ₄异质结构具有高导电性和快速电荷转移、丰富的活性位点和高催化反应性，使其具有优异的性能。