Mechanism of Oxygen Reduction Reaction on Monolayer WTe<sub>2</sub> with and without S Dopant at Low Coverage

Transition metal dichalcogenides possess properties such as low cost, easy fabrication, and suitability for various applications. Monolayer WTe2 is a potential electro-catalytic material for the oxygen reduction reaction (ORR). However, the reaction mechanism on pure and S-doped monolayer WTe2 remains unknown; therefore, this work is devoted to clarifying the current topic using density functional theory calculations and a thermodynamics model. We found that the ORR mechanism is a four-electron pathway on pure and S-doped monolayer WTe2. However, S-doped monolayer WTe2 increases the thermodynamic barrier of the ORR compared to pure monolayer WTe2. Therefore, the S dopant decreases the performance of WTe2. The result implies that doping with different elements is not always a method to improve the efficiency of chemical reactions.