A novel dicobalt-substituted tungstoantimonate polyoxometalate: Synthesis, characterization, and photocatalytic water oxidation properties

Abstract

The one-pot assembly reaction of a trilacunary, lone-pair-containing [B-α-SbW9O33]9− precursor with Co2+ ions in an aqueous medium led to the isolation of a novel {SbO3 (H2O)3} bridging, dicobalt-substituted, sandwich-type tungstoantimonate {Co2Sb2 (H2O)10 [B-β-SbW9O33]2}4− (1a). This compound was structurally characterized in the solid state by single-crystal X-ray diffraction, elemental analyses, thermogravimetric analysis, and IR spectroscopy. The most remarkable feature was that 1a comprises two trilacunary [B-β-SbW9O33]9− fragments trapping a novel, centrally symmetric, rhomb-like {Co2 Sb2} belt with 10 terminal water molecules. When combined with the photosensitizer [Ru(bpy)3]2+ and the sacrificial electron acceptor S2O82−, 1a exhibited efficient catalytic activity for water oxidation with a remarkable turnover number (TON) of 193, initial turnover frequency (TOFinitial) of 5.3 s−1, O2 yield of 30.8%, and quantum yield (ΦQY) of 36.2% under light-driven conditions.