Carbazolic Conjugated Organic Polymers for Visible-Light-Driven CO 2 Photoreduction with H 2 O to CO with High Efficiency and Selectivity.

Visible-light-driven CO 2 photoreduction with H 2 O to value-added chemicals in high efficiency and selectivity is significant but challenging. Herein, a series of carbazolic conjugated organic polymers (CB-COPs) with electron donor-acceptor (D-A) structures were prepared, which showed high efficiency for visible-light-driven photocatalytic reduction of CO 2 with H 2 O in a solid-gas mode, affording CO as the exclusive carbonaceous product. Especially, CB-COP-mpd derived from 3,5-di(9H-carbazol-9-yl)pyridine exhibited the highest CO evolution rate up to 191.46 μmol g -1  h -1 with a selectivity of 100 %. Mechanism studies showed that carbazolyl is a promising electron donor candidate for constructing CB-COPs with D-A structures, capable of improving the catalytic efficiency and suppressing H 2 generation. The acceptor building block with excessive electron withdrawing capability was favorable to H 2 O adsorption, thus resulting in the generation of H 2 . This work provides new insights for designing COPs photocatalysts for CO 2 photocatalytic reduction.