Transition metal atom anchored by defective WSSe monolayer as bifunctional single atom catalyst for ORR and OER

Bifunctional electrocatalysts with high catalytic activity toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key for developing efficient energy conversion and storage technology. Here, we investigated the ORR and OER electrocatalytic activity of transition metal atoms (TM) anchored at the S and Se vacancy sites of WSSe monolayer (TM@S-WSSe, TM@Se-WSSe) via performing the first-principles calculation. Our result shows that the single atom catalysts (SACs) Pt@S-WSSe and Pt@Se-WSSe have low ORR/OER overpotentials (η^ORR/η^OER) of 0.31/0.36 V and 0.43/0.34 V, respectively. The η^ORR and η^OER at SAC Pt@S-WSSe are even lower compared with the previously studied SACs. Besides, the Gibbs free energy changes of the key intermediate adsorption are close to the values at ideal catalyst. Our calculations demonstrate the promising potential of Pt@S-WSSe and Pt@Se-WSSe as ORR and OER bifunctional SACs. More importantly, the superior ORR and OER catalytic activity of TM@S-WSSe and TM@Se-WSSe are well explained via the intrinsic feature of SACs as well as the interaction between the TM atom and the intermediates. Especially, we demonstrate that the magnetic moment and the catalytic activity of SACs TM@S-WSSe and TM@Se-WSSe is closely correlated. Our result provides new idea for designing highly effectual ORR and OER bifunctional SACs.