A Hexadecanuclear Cobalt-Added Tungstogermanate Containing Counter Cobalt Hydrates: Synthesis, Structure and Photocatalytic Properties.

The synthesis and exploration of the properties of structurally-new polyoxometalates (POMs) has been attracting considerable research interest. In this work, a hexadecanuclear cobalt-added tungstogermanate, H(NH)Na{Co(HO)}{Co(μ-OH)(PO)}·23-HO (), was synthesized under hydrothermal conditions and characterized by various techniques. Compound can effectively drive the heterogeneous photocatalytic hydrogen evolution reaction in the presence of [Ir(ppy)(dtbbpy)][PF] as the photosensitizer, with triethanolamine (TEOA) and N-Hydroxy succinimide (NHS) used as the dual sacrificial reagents. Control experiments revealed the important role of NHS in enhancing the hydrogen-evolution activities. Under optimal catalytic conditions, a hydrogen yield of 54.21 μmol was achieved after 10-h photocatalysis, corresponding to a hydrogen evolution rate of 1807.07 μmol·g·h. Stability studies demonstrated that catalyst can be isolated and reused for three successive photocatalytic cycles with negligible decline of the H yield, indicating the stability and recycling robustness of catalyst .