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

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.