First principles, plane wave self-consistent field calculations were executed using the generalized gradient approximation (GGA) method using QUANTUM ESPRESSO. 33a Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional with projector-augmented wave type pseudopotentials were used to treat electron core interactions in all the atoms. A kinetic energy and charge density cut-off of 30 Ry and 300 Ry, respectively, were applied for better convergence. The slab models for Cu contained four atomic layers with the bottom two layers fixed, while the slab models for CTC contained 1 Sn atom and 2 Cl atoms on the surface of 5 nuclear layers of Cu with the bottom two layers fixed. In the aperiodic directions, at least 15Ǻ vacuum space was added to each model to avoid interactions between neighbouring images. The structural coordinates of the relaxed Cu, CTC, CTC-CO and CTC-CO-K slabs are given in the supporting information. Complete structural relaxation with k- mesh of 6 × 6 × 1 was performed until the total energy was converged to 10 -5 eV and the residual forces on all unconstrained atoms were less than 0.02 eV Ǻ -1 . The conducting nature of the system was incorporated through the method of tetrahedra in calculating the electronic properties. The binding energy of CO and K was computed as the difference between the energy of the composite system and the sum of the energies of the clean surface and uncoordinated adsorbate. GDEs. Briefly, the electrochemical performance of the CTC electrodes is done by bubbling CO2 into the cathode compartment electrolyte (catholyte) at a flow rate of 50 mL min -1 , and a constant potential was applied to the SnCl4/Cu2O cathodes with a potentiostat. The effluent gas stream was collected, and the reaction products were analysed every 30 min with gas and ion chromatography.