First Principles Calculations Combining Microkinetic Model for MXene Supported Single Atom Catalysts Screening and...

The dynamic co-adsorption of possible intermediates on the single atom catalysts (SACs) under working conditions critically influences the mechanisms of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). This work investigates oxygen vacancy site supported single atoms on MXene W₂CO₂ (M₁-W₂CO₂) using density functional theory (DFT) and microkinetic simulations to reveal the effect of dynamic adsorption. The screening results differ significantly with and without considering this effect. Without dynamic adsorption, only Pt₁-W₂CO₂(O_v) and Au₁-W₂CO₂(O_v) are identified as OER and ORR SACs, respectively. When further considering single intermediate adsorption, more M₁-W₂CO₂(O_v) are screened out as promising OER SACs such as Pt₁(Rh₁, Ni₁)-W₂CO₂(O_v), and ORR SACs such as Pt₁(Ag₁, Au₁)-W₂CO₂(O_v). The reason for the difference is the ΔG_*OH with intermediates (*OH, *O) covered moves toward the optimal region of the volcano plot for ΔG_L and ΔG_*OH. Compared with uncovered case, the d-band center of Pt₁(Rh₁, Ni₁) decreases with *OH covered, and adsorbate surface interaction weakens, which means ΔG_*OH would increase. Considering multiple intermediates yields the same trend. This study highlights the importance of dynamic adsorption in theoretical screening and provides guidance for designing efficient single-atom electrocatalysts for OER and ORR.