Installing earth-abundant metal active centers to covalent organic frameworks for efficient heterogeneous photocatalytic CO2 reduction

Photocatalytic conversion of CO2 into energy carriers has been recognized as a highly promising strategy for achieving the virtuous carbon cycle in nature. The realization of this process depends on an efficient catalyst to reduce the reaction barrier. Herein, we report a series of transition metal ion modified crystalline covalent organic frameworks (COFs) for the heterogeneous photocatalytic reduction of CO2. By coordinating different kinds of open metal active species into COFs, the resultant DQTP (2,6-diaminoanthraquinone - 2,4,6-tri-formylphloroglucinol) COF-M (M = Co/Ni/Zn) exerts a strong influence on the activity and selectivity of products (CO or HCOOH). Significantly, DQTP COF-Co exhibits a high CO production rate of 1.02 x 10(3)mu mol h(-1) g(-1), while DQTP COF-Zn has a high selectivity (90% over CO) for formic acid generation (152.5 mu mol h(-1) g(-1)). This work highlights the great potential of using stable COFs as platforms to anchor earth-abundant metal active sites for heterogeneous CO2 reduction.