A polyanion cluster H6Na8Cs3[Co9(μ3-OH)3(H2O)6(HPO4)2(B-α-PW9O34)3]Cl·40H2O (1) was made with the guidance of the lacunary directing strategy under hydrothermal conditions. Compound 1 was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and thermogravimetric analysis, respectively. Single-crystal X-ray diffraction analyses showed that 1 consists of three anions [B-α-PW9O34]9- and a cyclic cationic [Co9(μ3-OH)3(H2O)6]15+ and two anions HPO42-. Variable-magnetic properties indicate antiferromagnetic interactions in 1. Visible-light-driven hydrogen evolution tests demonstrated that 1 was an efficient water reduction catalyst with an H2 evolution rate of 1217.6 μmol h-1 g-1.
Keywords: hydrothermal syntheses; lacunary directing strategy; polyoxometalates; visible-light-driven hydrogen evolution.