Highly efficient, selective, and durable photocatalytic system for CO₂ reduction to formic acid

We discovered an extremely suitable sacrificial electron donor, 1,3-dimethyl-2-(o-hydroxyphenyl)-2,3-dihydro-1H-benzo[d]imidazole, for the selective photocatalytic reduction of CO₂ to formic acid using a Ru(II)–Ru(II) supramolecular photocatalyst. The efficiency, durability, and rate of photocatalysis are significantly increased (Φ_HCOOH = 0.46, TON_HCOOH = 2766, TOF_HCOOH = 44.9 min⁻¹) in comparison with those using 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole or 1-benzyl-1,4-dihydronicotinamide.