Covalent attachment of a molecular CO2-reduction photocatalyst to mesoporous silica

A molecular CO2-reduction photocatalyst, Re(bpy)(CO)3Cl where bpy = 2,2′-bipyridine, was successfully immobilized on mesoporous silica through covalent attachment and physical adsorption. The covalently attached Re(I) complex demonstrated excellent stability under photochemical conditions and higher activity than its homogeneous counterpart in solar CO2 reduction. In contrast, the physically adsorbed Re(I) complex showed poor photochemical stability and activity. Furthermore, the covalently attached Re(I) photocatalyst possess enhanced absorption in the visible-light region due to derivatization of the bpy ligand with amido groups. Our study suggests that covalent attachment through simple organic linkages is a promising strategy to immobilize molecular CO2-reduction photocatalysts on solid-state surfaces.

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► A molecular photocatalyst was immobilized on mesoporous silica for CO2 reduction.
► Covalent attachment via amide linkages led to enhanced visible-light photoresponse.
► Covalently attached photocatalyst showed excellent stability and good activity.