Efficient CO2 Capture and In-Situ Electrocatalytic Conversion on MgO Surface by Metal Single-Atom Engineering: A Comprehensive DFT Study

CO2 capture and electrochemical CO2 conversion are both extremely energy-intensive processes, and synergistic coupling between the two processes can increase the ecological sustainability of the system and decrease the cost of the generated products. Here, we investigated the enhancement of CO2 capture performance on MgO (100) surface by thirteen types of metal single -atom engineering using density functional theory (DFT) method. The doping of Pt, Ru, or Rh single atom transforms the adsorption of CO2 on the surface of MgO (10 0) from physical to chemical processes. The MgO surface doped with Ru single atom has the maximum CO2 adsorption energy of -1.46 eV. Notably, this chemical interaction with the surface activates inactive O = C = O bond of CO2 significantly, which is advantageous for the generation of the intermediate *COOH during the electrochemical conversion process. Reaction pathway analysis shows that Ru@MgO surface exhibits high activity and selectivity for the electrochemical conversion of CO2 to CH4. DFT results show that Ru@MgO can be used to separate CO2 from flue gas and electro-catalyze CO2 into CH4 in-situ efficiently, paving the way for the development of a novel CO2 separation technology with low energy consumption and high efficiency.