Electronic regulation of MoS2 edge sites by d electron transfer of Ni or Co to improve the activity of CO sulfur-resistant methanation

[Display omitted] •Doping Ni/Co to MoS2 shifts d-band center to Fermi level, getting more CO adsorbed.•The d-electrons transfer from Ni/Co to Mo occurred that promoted S vacancies.•The rate-limiting step for CO methanation on Ni or Co doped MoS2 was CO + H→*CHO. The catalyst modified by the difference of transition metal d orbital electrons is a promising strategy to promote its catalytic activity, which has been extensively studied in heterogeneous catalysis. Herein, Ni and Co transition metals were used to modify the MoS2 catalyst and promote activity for sulfur-resistant CO methanation. Characterization results indicated that Ni or Co atoms could be successfully doped into the edge-site of MoS2, which generated more S-vacancy at Mo-edge site and enhanced sulfur-resistant CO methanation activity. The roles of Ni and Co doping in improving activity were explored based on DFT calculation. It was found that Ni or Co could modify the electronic structure, weaken the strength of their interaction with edge S atoms and promote the spontaneous formation of more S vacancies at Mo edge sites. This leads to enhancing the adsorption of CO and weakening the bonding energy between C-O, which implied the facilitation of CO hydrogenation. Moreover, the modified Ni(Co)-Mo-S active sites facilitate the rate-determining step of CO hydrogenation activation to form *CHO species, which contributes to the enhanced activity for sulfur-resistant CO methanation. This work provides an attractive method for modifying MoS2 catalysts for sulfur-resistant CO methanation.