Steric hindrance- and work function-promoted high performance for electrochemical CO methanation on antisite defects of MoS2 and WS2

CO methanation from electrochemical CO reduction reaction (CORR) is significant for sustainable environment and energy, but electrocatalysts with excellent selectivity and activity are still lacking. Selectivity is sensitive to the structure of active sites, and activity can be tailored by work function. Moreover, intrinsic active sites usually possess relatively high concentration compared to artificial ones. Here, antisite defects Mo S2 and W S2 , intrinsic atomic defects of MoS 2 and WS 2 with a transition metal atom substituting a S 2 column, are investigated for CORR by density functional theory calculations. The steric hindrance from the special bowl structure of Mo S2 and W S2 ensures good selectivity towards CO methanation. Coordination environment variation of the active sites, the under-coordinated Mo or W atoms, effectively lowers the work function, making Mo S2 and W S2 highly active for CO methanation with the required potential of -0.47 and -0.49 V vs. reversible hydrogen electrode, respectively. Moreover, high concentration of active sites and minimal structural deformation during the catalytic process of Mo S2 and W S2 enhance their attraction for future commercial application.