Efficient and Selective Electrochemical CO₂ to Formic Acid Conversion: A First-Principles Study of Single-Atom and Dual-Atom Catalysts on Tin Disulfide Monolayers

Electrochemical CO₂ reduction reaction (CO₂RR) is a sustainable approach to recycle CO₂ and address climate issues but needs selective catalysts that operate at low electrode potentials. Single-atom catalysts (SACs) and dual-atom catalysts (DACs) have become increasingly popular due to their versatility, unique properties, and outstanding performances in electrocatalytic reactions. In this study, we used Density Functional Theory along with the computational hydrogen electrode methodology to study the stability and activity of SACs and DACs by adsorbing metal atoms onto SnS₂ monolayers. With a focus on optimizing the selective conversion of CO₂ to formic acid, our analysis of the thermodynamics of CO₂RR reveals that the Sn-SAC catalyst can efficiently and selectively catalyze formic acid production, being characterized by the low theoretical limiting potentials of −0.29 V. The investigation of the catalysts stability suggests that structures with low metal coverage and isolated metal centers can be synthesized. Bader analysis of charge redistribution during CO₂RR demonstrates that the SnS₂ substrate primarily provides the electronic charges for the reduction of CO₂, highlighting the substrate’s essential role in the catalysis, which is also confirmed by further electronic structure calculations.