Dual activation and C-C coupling on single atom catalyst for CO 2 photoreduction

An excellent single-atomic photocatalyst, Ti@C 4 N 3 , is theoretically found to effectively convert CO 2 to C 2 H 6 by density functional theory (DFT) calculations and non-adiabatic molecular dynamics (NAMD) simulations. The Ti@C 4 N 3 photocatalyst has remarkable stability both thermally, chemically, and mechanically. Electronically, it has strong absorption properties ( λ = 327.77 and 529.61 nm), suitable band positions, and a long photogenerated electron lifetime ( τ e = 38.21 ps), allowing photogenerated electrons to migrate to the surface. Notably, the high-valence active site effectively activates two CO 2 through dual activation: Under light irradiation, the weakly adsorbed CO 2 undergoes photo-induced activation by the photoelectron of conduction band minimum (CBM); without light, the high Lewis acidity of the Ti site induces CO 2 activation through back-donating π-bond. Contrast simulation results uncovered that dual activation of CO 2 is attributed to the thermal and photonic synergy. Furthermore, two activated CO 2 species under light easily couple to form oxalate with the barrier of 0.19 eV, and further reduced to C 2 H 6 with a low activation energy of 1.09 eV.