Efficient Electrochemical Detection of Hydrogen Peroxide Based on Silver-Centered Preyssler-Type Polyoxometalate...

Four polyoxometalate (POM)-based organic-inorganic hybrid compounds, namely, (H₂bimb)₆H₈[((Mn(H₂O)₃(μ-bimb))_0.5(Mn(H₂O)₄)(Mn(H₂O)₅)_0.5(AgP₅W₃₀O₁₁₀))₂]·29H₂O (1), [(Cu(Hbimb)(H₂O)₂(μ-bimb)Cu(Hbimb)(H₂O))(Cu(H₂O)₂(μ-bimb)Cu(H₂O)₃)((Cu(H₂O)₂)_0.5(μ-bimb)(Cu(H₂O)₃)_0.5)H₂(AgP₅W₃₀O₁₁₀)]·12.5H₂O (2), (H₂bimb)₂H[(Zn(Hbimb)(H₂O)₄(Zn(Hbimb)(H₂O)₂)_0.5)₂(AgP₅W₃₀O₁₁₀)]·12H₂O (3), and (H₂bimb)₃H₂[(Ag(H₂O)₂)_0.5(Ag(Hbimb)Ag(Hbimb)(μ-bimb)Ag)(Ag(H₂O)₂)_0.5(AgP₅W₃₀O₁₁₀)]·7H₂O (4) (bimb = 1,4-bis(1H-imidazol-1-yl)benzene), were hydrothermally synthesized using a silver-centered Preyssler-type POM K₁₄[AgP₅W₃₀O₁₁₀]·18H₂O (abbreviated as K-{AgP₅W₃₀}) as a precursor. In 1-4, {AgP₅W₃₀} clusters integrating the merits of Ag⁺ and {P₅W₃₀} units are modified by different transition metal (TM)-organic fragments to extend the structures into three-dimensional frameworks. As nonenzymatic electrochemical sensor materials, 1-4 show good electrocatalytic activity, high sensitivity, and a low detection limit for detecting hydrogen peroxide (H₂O₂); 4 possesses the highest sensitivity of 195.47 μA·mM^-1·cm^-2 for H₂O₂ detection. Most importantly, the average level of H₂O₂ detection of these {AgP₅W₃₀}-based materials outperforms that of Na-centered Preyssler-type {NaP₅W₃₀} and most Keggin-type POM-based materials. The performances of such {AgP₅W₃₀} materials mainly stem from the unique advantage of high-negatively charged {AgP₅W₃₀} clusters together with the good synergistic effect between {AgP₅W₃₀} and TMs. This work expands on the research of high-efficiency POM-based nonenzymatic electrochemical H₂O₂ sensors using Ag-containing POMs with high negative charges, which is also of great theoretical and practical significance to carry out health monitoring and environmental analysis.