A New Bis-Keggin Polyoxometallate-Based Bifunctional Catalyst for Efficient Electrochemical Sensing and Photocatalytic Reduction of Cr(VI)

A new polyoxometalate (POM)-based compound {[Co(H₂O)₆](H₂L)₃[H₂[(Co_0.5W_0.5)SiW₁₁O_39.5]₂} [L = N,N′-bis(3-menthylpyridin-yl)naphthalene-2,6-dicarboxamide], was synthesized using a solvothermal method. In this structure, two [(Co_0.5W_0.5)SiW₁₁O₄₀] units are linked by co-vertex oxygen to form a bis-Keggin polyoxometalate dimer, which binds to [Co(H₂O)₆] clusters via hydrogen bonding to form a 1D inorganic chain. The diprotonated organic ligands H₂L²⁺ and the 1D inorganic chains are interconnected by hydrogen bonds to form the 3D supramolecular network. The prepared polyoxometalate compound can be used as a bifunctional material for the electrochemical determination and photocatalytic reduction of Cr(VI) with good performance [LOD: 0.959 μM, reduction rate: 97.5%]. The corresponding anti-interference ability and cycle stability are also studied.