Precisely tailoring the electronic structures of electrocatalysts to achieve an optimum hydroxide binding energy (OHBE) is vital to the alkaline hydrogen oxidation reaction (HOR). As a promising alternative to the Pt-group metals, considerable efforts have been devoted to exploring highly efficient Ni-based catalysts for alkaline HOR. However, their performances still lack practical competitiveness. Herein, based on insights from the molecular orbital theory and the Hammer–Nørskov d-band model, we propose an ingenious surface oxygen insertion strategy to precisely tailor the electronic structures of Ni electrocatalysts, simultaneously increasing the degree of energy-level alignment between the adsorbed hydroxide (*OH) states and surface Ni d-band and decreasing the degree of anti-bonding filling, which leads to an optimal OHBE. Through the pyrolysis procedure mediated by a metal–organic framework at a low temperature under a reducing atmosphere, the obtained oxygen-inserted two atomic-layer Ni shell-modified Ni metal core nanoparticle (Ni@O_i-Ni) exhibits a remarkable alkaline HOR performance with a record mass activity of 85.63 mA mg^–1, which is 40-fold higher than that of the freshly synthesized Ni catalyst. Combining CO stripping experiments with ab initio calculations, we further reveal a linear relationship between the OHBE and the content of inserted oxygen, which thus results in a volcano-type correlation between the OH binding strength and alkaline HOR activity. This work indicates that the oxygen insertion into the top-surface layers is an efficient strategy to regulate the coordination environment and electronic structure of Ni catalysts and identifies the dominate role of OH binding strength in alkaline HOR.

中文翻译：

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用于促进碱性氢氧化电催化的插氧镍顶面层

精确调整电催化剂的电子结构以获得最佳的氢氧化物结合能 (OHBE) 对于碱性氢氧化反应 (HOR) 至关重要。作为 Pt 族金属的有希望的替代品，人们投入了大量精力来探索用于碱性 HOR 的高效 Ni 基催化剂。但是，他们的表现仍然缺乏实际竞争力。在此，基于分子轨道理论和 Hammer-Nørskov d 带模型的见解，我们提出了一种巧妙的表面氧插入策略来精确定制 Ni 电催化剂的电子结构，同时提高吸附之间的能级对齐程度氢氧化物 (*OH) 状态和表面 Ni d 带并降低反键填充程度，从而导致最佳 OHBE。_i- Ni) 表现出显着的碱性 HOR 性能，质量活性为 85.63 mA mg ^–1，比新合成的 Ni 催化剂高 40 倍。将 CO 汽提实验与从头计算相结合，我们进一步揭示了 OHBE 与插入氧含量之间的线性关系，从而导致 OH 结合强度与碱性 HOR 活性之间存在火山型相关性。这项工作表明，将氧插入顶表层是调节 Ni 催化剂的配位环境和电子结构的有效策略，并确定了 OH 结合强度在碱性 HOR 中的主导作用。