Edge engineering on layered WS 2 toward the electrocatalytic reduction of CO 2 : a first principles study.

Transition-metal dichalcogenides (TMDCs) have been modified to show excellent electrocatalytic performance for the CO reduction reaction (CORR). However, little research has been reported on the edge modification of WS and its electrocatalytic CORR. In this work, the edge structure of WS with W atoms exposed in the top layer was established by density functional theory calculations. Through using WS-TM- ( = 1, 2 or 3; = 1 or 2; TM = Zn, Fe, Co or Ni) models by doping TM atoms on the top layer of WS, the effects of dopant species, doping concentration and adsorption sites on their electrocatalytic activity were investigated. Among the models, the active site for the CORR is the W atoms. The doping of TM atoms would affect the bond strength between W and S atoms. After the doping of TM atoms in WS-2TM-1 ones, the electrical conduction of S atoms and the underlying W atoms can greatly be improved. Thus the catalytic activities can be significantly increased, in which the WS-2Zn-1 model shows the best catalytic activity. The limiting potential () of the CORR to CO on the WS-2Zn-1 model is -0.51 V and the Gibbs energy change (Δ) for the adsorption of intermediates on the WS-2Zn-1 model is Δ(COOH*) = -0.37 and Δ(CO*) = -0.51 eV, respectively. Solvation correction showed that WS-2Zn-1 could maintain good catalytic performance in a wide range of pH values. The present results may provide a theoretical basis for the design and synthesis of novel electrocatalysts with high performance for the CORR.