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

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, suitable band positions, and a long photogenerated electron lifetime, 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.

一种卓越的单原子光催化剂，Ti@C₄N₃，经密度泛函理论（DFT）计算和非绝热分子动力学（NAMD）模拟，理论研究表明其能有效将CO₂转化为C₂H₆。Ti@C₄N₃光催化剂在热、化学和机械稳定性方面均表现出显著特性。电子学性质上，其具有强吸收特性、适宜的能带位置以及较长的光生电子寿命，使得光生电子能够迁移至表面。尤为值得注意的是，高价态活性位点能够通过双重激活机制有效地激活两个CO₂分子：在光照条件下，弱吸附的CO₂通过导电带最低点（CBM）的光电子诱导发生光诱导激活；而在无光照的情况下，Ti位点的强路易斯酸性通过反捐赠π键诱导CO₂的激活。对比模拟结果表明，CO₂的双重激活归因于热与光学的协同效应。此外，在光照条件下，两个被激活的CO₂物种易于结合形成草酸，其能量障碍仅为0.19 eV，并进一步以低至1.09 eV的活化能还原为C₂H₆。