Abstract:

By the means of density functional theory calculation (DFT) and ab initio molecular dynamics (AIMD) simulation, the capacities of hydrogen activation and hydrogen spillover over Co₉S₈ surface were examined. The optimized structure, reaction and activation energy of hydrogen dissociative adsorption and the spillover network, and stability of S—H or Co—H bond were all calculated. The results showed that certain S-top site, Co-top site, S-Co-bridge site and S-Co-multi-membered-ring site were available for dissociation, and the molecular hydrogen could be effectively activated by two adjacent S-top sites of (111) surface. The AIMD simulation for S—H bonds of S-top site testified the current towards breaking, and then the spillover network calculation further proved the hydrogen migration was kinetically unlimited over (001) and (111) surfaces. In short, the Co₉S₈ surface indicated excellent performance in the area of hydrogen dissociation and hydrogen spillover, which represented enormous potential for hydrogen spillover in CoMoS catalytic system.

Key words: hydrogen activation, hydrogen spillover, Co₉S₈, CoMoS, density functional theory

摘要：

采用密度泛函理论（DFT）计算及从头算分子动力学（AIMD）模拟方法，深入分析了Co₉S₈的氢活化及氢溢流性能。对氢解离吸附的构型优化、反应能、活化能以及氢溢流网络、S—H键与Co—H键的稳定性进行了计算。研究结果显示，在特定的S-top位、Co-top位、S-Co-bridge位和S-Co-多元环位上，氢分子能够发生解离吸附，且分子氢可以在(111)表面两个相邻的S-top位点被高效活化。AIMD模拟结果验证了S-top位的S—H键断裂的倾向，并且氢溢流网络进一步揭示了(001)和(111)两表面氢溢流在动力学上的高度可行性。综上，Co₉S₈表面在氢解离和氢溢流方面展现出优异的性能，在CoMoS催化体系中具有显著的氢溢流潜力。

关键词: 氢活化, 氢溢流, 八硫化九钴, CoMoS, 密度泛函理论