Facilitated Photocatalytic CO2 Reduction in Aerobic Environment on a Copper‐Porphyrin Metal–Organic Framework

Herein, we fabricated a π–π stacking hybrid photocatalyst by combining two two‐dimensional (2D) materials: g‐C3N4 and a Cu‐porphyrin metal–organic framework (MOF). After an aerobic photocatalytic pretreatment, this hybrid catalyst exhibited an unprecedented ability to photocatalytically reduce CO2 to CO and CH4 under the typical level (20 %) of O2 in the air. Intriguingly, the presence of O2 did not suppress CO2 reduction; instead, a fivefold increase compared with that in the absence of O2 was observed. Structural analysis indicated that during aerobic pretreatment, the Cu node in the 2D‐MOF moiety was hydroxylated by the hydroxyl generated from the reduction of O2. Then the formed hydroxylated Cu node maintained its structure during aerobic CO2 reduction, whereas it underwent structural alteration and was reductively devitalized in the absence of O2. Theoretical calculations further demonstrated that CO2 reduction, instead of O2 reduction, occurred preferentially on the hydroxylated Cu node. After aerobic pretreatment, the MOF node of the hybrid catalyst was hydroxylated and exhibited an unprecedented ability to photocatalytically reduce CO2 to CO and CH4. Intriguingly, the addition of 20 % O2 did not suppress CO2 reduction; rather, a fivefold increase was found when compared to the lack of O2.