The synergistic effect of Ni promoter on Mo-S/CNT catalyst towards hydrodesulfurization and hydrogen evolution reactions

The effects of Ni promoter on Mo-S/CNT catalyst towards hydrodesulfurization (HDS) and hydrogen evolution reactions (HER) were studied. Ni promoter was introduced into Mo-S/CNT catalyst by one-step or mechanical mixing method, and Ni species presented in the form of Ni-Mo-S or Ni₃S₄, respectively. Catalytic assessments indicated that Ni-Mo-S structure had obviously better HDS and HER activities than MoS₂ at the same time, while Ni₃S₄ could not improve the activity of MoS₂ towards HDS or HER. The density functional theory (DFT) was also used to simulate and calculate the activation energies needed for HDS and HER on MoS₂ structure and Ni-Mo-S structure, respectively. It was found that the required activation energies for C–S bond breaking and H₂ generation on Ni-Mo-S structure were both significantly lower than that of MoS₂ structure. Therefore, it was proved theoretically that compared with MoS₂ structure, Ni-Mo-S structure had better catalytic activities for both HDS and HER.