To generate “green hydrogen,” electrochemical water splitting is regarded as the most promising method, which requires highly efficient bifunctional electrocatalysts to accelerate the hydrogen and oxygen evolution reactions (HER and OER). Herein, a “d-electron complementation” principle to develop such candidates is proposed. By taking advantage of the filling characteristics of 3d orbitals, vanadium-cobalt phosphide (V-CoP) is synthesized. According to X-ray absorption fine structure and X-ray photoelectron spectroscopy investigation, V can disorder the coordination environment of Co, leading to increased/decreased charge density in Co(P)/Co(O). As a result, V-CoP shows impressive bifunctional activity, which only needs overpotentials of 46 and 267 mV to deliver 10 mA cm⁻² for the HER and OER, respectively. Density functional theory calculations reveal that the accelerated H₂O dissociation process on the VO_x/CoO_x/CoP surface and H conversion kinetics on the V-neighboring CoCo bridge site result in promoted HER activity. Furthermore, the up-shifted d-band center of V-CoOOH endows the V-neighboring Co site with a lowered energy barrier for the OER. This work serves as a proof-of-concept for the application of the “d-electron complementation” principle, which can be a generalized guideline to design and develop novel highly efficient catalysts.

中文翻译：

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“d-电子互补”诱导的磷化钴，用于高效的整体水分解

为了产生“绿色氢”，电化学水分解被认为是最有前途的方法，它需要高效的双功能电催化剂来加速析氢和析氧反应（HER和OER）。在此，提出了开发此类候选物的“d-电子互补”原理。利用3d轨道的填充特性，合成了磷化钒钴（V-CoP）。根据 X 射线吸收精细结构和 X 射线光电子能谱研究，V 可以扰乱 Co 的配位环境，导致 Co(P)/Co(O) 中电荷密度的增加/减少。因此，V-CoP 显示出令人印象深刻的双功能活性，仅需要 46 和 267 mV 的过电位即可提供 10 mA cm ^-2分别为 HER 和 OER。密度泛函理论计算表明，VO _x /CoO _x /CoP 表面上加速的 H ₂ O 解离过程和 V 相邻 Co  Co 桥位上的 H 转化动力学导致 HER 活性的提高。此外，V-CoOOH 的上移 d 带中心赋予 V 相邻的 Co 位点降低的 OER 能垒。这项工作作为“d-电子互补”原理应用的概念验证，可以作为设计和开发新型高效催化剂的通用指南。