Water-Assisted Highly Efficient Photocatalytic Reduction of CO to CO with Noble Metal-Free Bis(terpyridine)iron(II) Complexes and an Organic Photosensitizer.

Photocatalytic CO reduction reaction is believed to be a promising approach for CO utilization. In this work, a noble metal-free photocatalytic system, composed of (terpyridine)iron(II) complexes and an organic thermally activated delayed fluorescence compound, has been developed for selective reduction of CO to CO with a maximum turnover number up to 6320, 99.4% selectivity, and turnover frequency of 127 min under visible-light irradiation in dimethylformamide/HO solution. More than 0.3 mmol CO was generated using 0.05 μmol catalyst after 2 h of light irradiation. The apparent quantum yield was found to be 9.5% at 440 nm (180 mW cm). Control experiments and UV-vis-NIR spectroscopy studies further demonstrated that water strongly promoted the photocatalytic cycle and terpyridine ligands rather than Fe(II) were initially reduced during the photocatalytic process.