Selective Photocatalytic CO2 Reduction via Enhanced CO2 Adsorption and Activation Over Co-Salen Functionalized Zr-MOF Catalyst.

Achieving highly selective production from photocatalytic CO2 reduction in aqueous systems remains a major challenge due to the competitive hydrogen evolution reaction (HER). Herein, we propose a node-docking strategy to graft Co-Salen molecular complexes onto Zr-MOF (NKM-906) to achieve the selective photoreduction of CO2 to CO. Experimental results demonstrate that the NKM-906 with unique SCU topology and microporous structure can effectively concentrate CO2 molecules near the Co-Salen active sites. Moreover, the confined Co-Salen exhibits superior adsorption and activation toward CO2 over H2O, which is a key factor in suppressing the HER. Density functional theory (DFT) calculations further indicate that, compared to other mononuclear (Ni, Cu, Zn, Mn) and binuclear (Co2) metal-Salen complexes, the mononuclear Co-Salen complex exhibits superior performance in the adsorption and activation of CO2. As a result, the Co-NKM-906 demonstrates a notable CO generation rate of 2.63 mmol g-1 h-1 with a CO selectivity of 83% in a water-containing system, indicating its outstanding catalytic efficacy in the selective photoreduction of CO2.