Highly efficient photosynthesis of syngas and pinacol from CO₂ and 1-phenylethanol via amine-regulated redox pathways

Integrating photocatalytic CO ₂ reduction with oxidative organic synthesis offers a promising policy for maximizing charge carrier utilization, enabling the simultaneous production of solar fuels and fine chemicals. Herein, highly efficient photoredox catalysis of CO ₂ reduction to syngas (CO: 467.1 μmol·h ^-1 , H ₂ : 78.4 μmol·h ^-1 ), coupled with 1-phenylethanol oxidation to pinacol (553.9 μmol·h ^-1 ) is attained over diethylenetriamine modified CdS, delivering a record-high apparent quantum yield of 25%, 100% pinacol selectivity, and a unity reaction stoichiometry. The amine groups effectively modulate both the reductive and oxidative pathways by enhancing CO ₂ capture and activation and stabilizing C-centered radicals, respectively. Also, they prompt charge carrier separation and transfer by forming strong Cd-N bonds with CdS. Mechanistic studies reveal that excited holes drive 1-phenylethanol oxidation to pinacol via carbon radical dimerization, while donating protons to boost CO ₂ -to-CO reduction via sequential proton-assisted electron transfer processes. This work lights up the route for building advanced artificial photosynthetic systems through precise surface engineering with functional organic groups.