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

• Published in: ChemPlusChem (Weinheim, Germany) Vol. 86; no. 7; pp. 1014 - 1020
• Main Authors: Liu, Xiao‐Mei, Kang, Run‐Kun, Wang, Ji‐Lei, Li, Jia‐Nian, Chen, Qiao‐Ling, Xu, Yan
• Format: Journal Article
• Language: English
• Published: 01.07.2021
• Subjects: CO2 conversion; inorganic cluster; photocatalysis; polyoxometalate; quasi-Keggin structure
• ISSN: 2192-6506; 2192-6506
• DOI: 10.1002/cplu.202100260

A pure inorganic cluster, H47Na2Co4Mo24(PO4)11O72 ⋅ 15H2O (denoted as {Co4Mo24}), has been successfully synthesized by hydrothermal method. Notably, the assembly of a central {Co2PO4} tetrahedron and four peripheral {Co[P4Mo6]} fragments gives rise to a rare “quasi‐Keggin” structure of {Co4Mo24}, 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 {P4Mo6} units and Co active centers, the photocatalytic system with {Co4Mo24} as heterogeneous catalyst exhibits excellent activity for CO2 conversion to CO, offering the CO formation rate of 1848.3 μmol g−1 h−1 with high selectivity of 97.0 %. Besides, thermogravimetric and X‐ray diffraction analysis confirm that {Co4Mo24} can maintain stable during the photocatalytic reaction process. One inorganic tetrameric cluster {Co4Mo24} has been successfully synthesized, which delivers a rare “quasi‐Keggin” structure by the assembly of {Co2PO4} tetrahedron and four {Co[P4Mo6]} fragments. Notably, {Co4Mo24} as heterogeneous catalyst exhibits excellent photocatalytic activity for CO2 conversion. Under 8 h irradiation, the rate of CO yield can reach up to 1848.3 μmol g−1 h−1 with high selectivity of 97.0 %.