Dual activation and C-C coupling on single atom catalyst for CO2 photoreduction

Abstract

Abstract An excellent single-atomic photocatalyst, Ti@C4N3, is theoretically found to effectively convert CO2 to C2H6 by density functional theory (DFT) calculations and non-adiabatic molecular dynamics (NAMD) simulations. The Ti@C4N3 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 CO2 through dual activation: Under light irradiation, the weakly adsorbed CO2 undergoes photo-induced activation by the photoelectron of conduction band minimum (CBM); without light, the high Lewis acidity of the Ti site induces CO2 activation through back-donating π-bond. Contrast simulation results uncovered that dual activation of CO2 is attributed to the thermal and photonic synergy. Furthermore, two activated CO2 species under light easily couple to form oxalate with the barrier of 0.19 eV, and further reduced to C2H6 with a low activation energy of 1.09 eV.