Stabilized Single-Atom Catalysts on 2D Supports for CO₂-to-Liquid Fuel Conversion: Beyond Conventional DFT Insights via Stability–Selectivity Descriptor Mapping

The electrochemical reduction of carbon dioxide (CO₂) into liquid fuels represents a promising pathway toward sustainable energy storage and carbon neutrality. Single-atom catalysts (SACs) have emerged as highly efficient systems due to their maximized atom utilization and tunable electronic structures. However, their practical application is hindered by poor stability and the tendency of isolated atoms to aggregate under reaction conditions. In this study, we propose the design of SACs stabilized on two-dimensional (2D) supports, specifically nitrogen-doped graphene and MXene substrates, to overcome these limitations. Density functional theory (DFT) simulations and experimental insights suggest that strong coordination between the single metal atom and heteroatom-doped 2D lattices can suppress migration and aggregation, thereby enhancing catalytic durability. Furthermore, the electronic coupling between the active site and the conductive 2D support facilitates charge transfer, improving selectivity toward C₂+ liquid products such as ethanol and propanol. This work highlights a rational strategy for engineering robust SACs and provides a pathway for scalable CO₂ valorization into high-value liquid fuels. In addition to conventional DFT analysis, we introduce a stability–selectivity descriptor framework that correlates adsorption energy, charge transfer, and limiting potential into a unified map. This approach enables rapid screening of SAC–support combinations beyond case-by-case simulations. Furthermore, we propose a conceptual design principle for dual-functional MXene–graphene hybrid supports, which has not been reported previously. These insights extend the scope of SAC design from incremental improvements toward predictive and scalable catalyst engineering.