A novel NbO-type framework constructed from Dawson-like tungstobismuthate and copper complex fragments

A rare organic–inorganic hybrid compound based on the Dawson-like tungstobismuthate, [H2bipy][Cu(bipy)(H2O)2][Cu(bipy)3][H3BiW18O60]·H2O (bipy: 4,4′-bipyridine) (1a) has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, cyclic voltammetry (CV) and powder XRD. Single-crystal X-ray analysis reveals that in 1a each tungstobismuthate fragment [H3BiW18O60]6− (BiW18) acts as a tetradentate ligand connecting four cationic chains of four Cu-bipy complexes via the terminal oxygen atoms to form a three-dimensional (3D) structure with NbO-type topology. The electrochemical behaviours of 1a were investigated in 0.5 M Na2SO4 + H2SO4 (pH 2.5) solutions by CV. In the potential range between −0.65 and 0.4 V, the compound 1a exhibits the successive redox processes of W and Cu. The electrocatalytic experiments indicate that the compound 1a has good electrocatalytic activities towards the reduction of NO2− and H2O2.