Understanding the mechanism of the alkaline hydrogen evolution reaction (HER) and finding a design principle to enhance the catalytic performance of electrocatalysts are of great significance in paving the way of alkaline water electrolysis. Here, taking cobalt phosphide (CoP) as a model material, we establish the alkaline HER activity trends as a function of a fundamental property, the proportion of the unoccupied 3d orbital (P_un). By doping CoP with a range of 3d and 4d transition metals with different P_un, we show that the intrinsic alkaline HER kinetics increases with P_un. DFT calculations indicate that the transition metals with higher P_un not only act as the oxophilic sites for enhanced water activation but also modulate the electronic structure of CoP to endow an optimized H adsorption (ΔG_∗H). Moreover, by further comparing the correlation between water adsorption and dissociation or ΔG_∗H and experimental alkaline HER activities, we find that water dissociation is the rate-determining step for alkaline HER.

理解碱性氢放出反应（HER）的机理并找到一种设计原理来增强电催化剂的催化性能，对碱性水电解的铺路具有重要意义。在这里，以钴磷（COP）作为模型材料，建立了碱性她的活动趋势，基本属性的功能，无人居住3d轨道（比例P _UN）。通过用不同的P _un掺杂一系列3d和4d过渡金属掺杂CoP ，我们表明固有的碱性HER动力学随P _un增加。DFT计算表明，P _un较高的过渡金属不仅充当增强水活化的亲氧位点，而且还调节CoP的电子结构以赋予最佳的H吸附（ΔG _{∗ H}）。此外，通过进一步比较水的吸附和解离或ΔG _{∗ H}与实验碱性HER活性之间的相关性，我们发现水解离是碱性HER的速率决定步骤。