Multichannel Photon Stimulated C-C Coupling for CO₂ Reduction in a Mixed Water/Acetonitrile Solvent

Designing effective photocatalysts for carbon dioxide reduction reaction (CO₂RR) requires a precise understanding of the dynamically photocatalytic mechanism under real conditions (e.g. solvent, light field). Herein, we coupled ab-initio non-adiabatic molecular dynamics (NAMD) simulation and density functional theory (DFT) calculation to theoretically reveal the detailed dynamic process for C-C Coupling under light field on Co-supported monolayer black phosphorus (BP) catalyst Co@BP. Specially, Co@BP features excellent property for photocatalyst: high stability, long-lived photogenerated carriers and stronger reducing ability. Thermodynamically, it shown that a dramatic difference in catalytic properties with 99.99 % selectivity for HCOOH in solvent-free condition (E_a=0.29 eV) and 99.34 % selectivity for CH₂CH₂ in solution (E_a=0.33 eV). Slow-growth based MD simulation results uncover that mixed solvent of water/acetonitrile (H₂O/ACN) is beneficial for the formation of C₂₊ product and the optimal ratio H₂O/ACN (1 : 9) mixture solvent for the conversion of CO₂ to CH₂CH₂. Under light irradiation, we found that multichannel photons enable adsorbed CHO* to couple with CHO species diffusing from nearby active sites, further forming C₂ intermediates in solution. This work highlights the importance of the reaction medium on the photogenerative carrier dynamics and offers a strategy to regulate product selectivity in photocatalytic CO₂ conversion.