Dual Regulation of Reduction and Oxidation Center in Metal–Organic Frameworks to Boost CO ₂ Photoreduction

Abstract

Abstract The efficiency of photocatalytic CO 2 reduction is governed by multiple critical factors, including visible‐light absorption, charge separation, hole utilization, and CO 2 adsorption/activation. However, simultaneous regulation of these factors in a single photocatalyst to facilitate CO 2 photoreduction remains underexplored. Herein, we proposed a dual‐regulation strategy to concurrently modulate the reduction center via heteroatom substitution and the oxidation center via 2,2,6,6‐tetramethylpiperidoxyl (TEMPO) coordination in cobalt porphyrin‐based metal–organic frameworks (Co‐MOFs), resulting in series of strong redox photocatalysts (TEMPO@Co‐XN 3 ‐MOF, X═N, O, and S) for efficient CO 2 photoreduction. Remarkably, CO yield with the dual‐regulated TEMPO@Co‐SN 3 ‐PCN can reach 2000 µmol g −1 , over 10 and 50 times higher than that with single‐regulated Co‐SN 3 ‐PCN and the typical Co‐N 4 ‐PCN, respectively. Moreover, the photogenegrated hole can efficiently drive the photooxidation of lactic acid to pyruvic acid with a 85% yield, while the in situ‐generated CO is directly utilized in a tandem carbonylation reaction to afford benzophenone with a 90% yield. Investigations reveal that the dual regulation of redox centers endows TEMPO@Co‐SN 3 ‐PCN with efficient hole utilzation, efficient charge separation, strong CO 2 adsorption and activation, thereby facilitating green‐synthesis of pyruvic acid and carbonyl compounds via a negative carbon emission process.