A Purely Inorganic Quasi‐Keggin Polyoxometalate for Photocatalytic Conversion of Carbon Dioxide to Carbon Monoxide

A pure inorganic cluster, H 47 Na 2 Co 4 Mo 24 (PO 4 ) 11 O 72  ⋅ 15H 2 O (denoted as { Co 4 Mo 24 }), has been successfully synthesized by hydrothermal method. Notably, the assembly of a central {Co 2 PO 4 } tetrahedron and four peripheral {Co[P 4 Mo 6 ]} fragments gives rise to a rare “quasi‐Keggin” structure of { Co 4 Mo 24 }, in which Co linkers continue to bridge adjacent substructures, resulting in the generation of 3D framework with large cavities. Benefitting from the combination of strong reductive {P 4 Mo 6 } units and Co active centers, the photocatalytic system with { Co 4 Mo 24 } as heterogeneous catalyst exhibits excellent activity for CO 2 conversion to CO, offering the CO formation rate of 1848.3 μ mol g −1 h −1 with high selectivity of 97.0 %. Besides, thermogravimetric and X‐ray diffraction analysis confirm that { Co 4 Mo 24 } can maintain stable during the photocatalytic reaction process.