Decoding CO₂ Adsorption Modes and CO Yield Variation on TM–N₄ Single-Atom Catalysts via Constant-Potential Computation and Machine-Learning Investigation

We then examined the CO₂RR processes by considering both adsorption modes of CO₂. The transition from CO₂ physisorption to chemisorption modes leads to a shift in the rate-limiting step from CO₂ hydrogenation to CO desorption, the emergence of new active sites for competing hydrogen evolution reactions, and a decrease in electron transfer rates at more negative potentials. Taken together, these observations align with the experimental CO yield profile under increasingly negative potentials, capturing key performance trends of rise, plateau, and decline.

Notably, the calculated <i>U</i>_trans values are consistent with the applied potentials at which CO yield declines for five SACs for which experimental data are available (Mn, Fe, Ni, Cu, and Zn). Thus, this work establishes <i>U</i>_trans as a novel predictive parameter for CO yield performance and offers valuable guidance for the design of advanced SACs in future studies.