Steric Hindrance‐ and Work Function‐Promoted High Performance for Electrochemical CO Methanation on Antisite Defects of MoS₂ and WS₂

Abstract

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, were investigated for CORR by density functional theory calculations. The steric hindrance from the special bowl structure of Mo S2 and W S2 ensured good selectivity towards CO methanation. Coordination environment variation of the active sites, the undercoordinated Mo or W atoms, effectively lowered the work function, making Mo S2 and W S2 highly active for CO methanation with the required potential of À 0.47 and À 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 enhanced their attraction for future commercial application.

Electrocatalytic Reduction of N2 to NH3 Over Defective 1T′‐WX2 (X=S, Se, Te) Monolayers

“…Indeed, the smaller the work function of a catalyst, the better its catalytic performance. Similar conclusion has been drawn for the catalytic activity of 2H‐MoS 2 in CORR by Yao et al [31b] . Our results suggest that steric hindrance at the defects strongly affect the catalytic activity, which can serve as a powerful handle to adjusting the activity of catalysts.…”

Recent advances in defect-engineered molybdenum sulfides for catalytic applications

“…In another Jiang's report, the authors proposed a bowl site structure, which can be a 2S-vacancy or a Mo atom substituting a S 2 column and the bowl sites can achieve the selective reduction of CO 2 to CH 4 . 177,180 In this configuration, *CO formed by CO 2 reduction is adsorbed in the bowl site and due to the steric hindrance, the adsorbate on the bowl site forms repulsive interaction with external species, thus preventing the hydrogenation of carbon and enabling the hydrogenation of oxygen, resulting in the formation of *COH instead of *CHO. Similarly, in the next step, *COH has difficulty forming *CHOH, but instead dehydrates to form *C, thus providing the basis for subsequent protonation to form CH 4 .…”

Work Function-Tailored Nitrogenase-like Fe Double-Atom Catalysts on Transition Metal Dichalcogenides for Nitrogen Fixation

“…Except for the ligand effect, tailoring the work function (φ) of catalysts is another effective strategy to regulate the performance, where a lower φ usually means better activity. − Since φ of MX 2 changes with both M and X variations, , φ of Fe 2 /MX 2 systems can be tailored by altering MX 2 supports. In this work, therefore, considering the similar chemical properties of elements in the same groups, 12 Fe 2 /MX 2 systems (M = V, Cr, Mo, and W; X = S, Se, and Te; NbX 2 and TaX 2 are not included because some of them are stable in 1T phase) with different φ values were thoroughly investigated for N 2 fixation by performing density functional theory (DFT) calculations.…”