While many metal compounds have been widely studied as electrocatalysts for hydrogen evolution reaction (HER), the mechanism of HER on these materials is still not well understood nor why one compound is more electrocatalytically active than another. Here, we report our findings in synthesis and characterization of several Co compounds (CoP, CoS and Co₃O₄) with similar morphology and uniform size but dramatically different HER activities. Electrochemical measurements indicate that CoP has the best HER activity, achieving an overpotential of 80 mV at 10 mA cm⁻², which is much smaller than those for CoS and Co₃O₄. DFT-based computations suggest that electron delocalization resulting from the p-d orbits coupling at the surfaces facilitates HER charge transfer kinetics and an optimal balance between the surface adsorption of H atom and desorption of H₂. Both experimental and computational analyses reveal that the HER activity of the Co compounds is correlated closely with the energy gap between the anion p-band and the Co d-band centers, which can be used as an effective descriptor for HER activity. This work offers the scientific basis for rational design of more efficient metal compound electrocatalysts with high HER activity.

尽管已经广泛研究了许多金属化合物作为放氢反应（HER）的电催化剂，但对于这些材料的HER机理仍未得到很好的理解，也不知道为什么一种化合物比另一种具有更高的电催化活性。在这里，我们报告了在几种形态相似，大小均一但HER活性显着不同的Co化合物（CoP，CoS和Co ₃ O ₄）的合成和表征中的发现。电化学测量表明，CoP具有最佳的HER活性，在10 mA cm ^-2时实现80 mV的过电势，比CoS和Co ₃ O _4的过电势小得多。基于DFT的计算表明，由p引起的电子离域- d轨道在表面处耦合便于HER电荷转移动力学和H原子的表面吸附和解吸为h之间的最佳平衡₂。实验和计算分析均表明，Co化合物的HER活性与阴离子p带和Co d带中心之间的能隙紧密相关，可以用作HER活性的有效描述子。这项工作为合理设计具有较高HER活性的更有效的金属化合物电催化剂提供了科学依据。