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

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.