A novel organic-inorganic hybrid assembled by [Mo8O26]4 clusters and {Cu(pic)2} units: Synthesis, crystal structure and electrochemical sensing properties

The rational design of crystalline materials coupled with polyoxometalate as electrocatalyst is an effective strategy for the sensitive electrochemical detection of H2O2. Here, a novel organic-inorganic hybrid complex [NH4]4[Cu(pic)2]3[Mo8O26] (1) (Hpic=2-picolinic acid) was synthesized via in situ self-assembly synthesis method and fully characterized. Structural analysis reveals that compound 1 adopts a two-dimensional (2D) layered structure based on the 1D {Mo8O26Cu(pic)2}n chains linked with the {Cu2(pic)4}n polymers via Cu-O bridge. The morphology of 1 features a columnar construct, smooth surface and sharp fringes with an average size of <50 µm. Electrochemical studies reveal that compound 1 exhibits the multi-electron redox processes ascribed to MoVI centers, and has good electrocatalytic activity for H2O2 reduction. By utilizing compound 1 as electrode material, the designed electrode shows excellent electrochemical performance for H2O2 detection, including a wide linear range (20–220 µM), high sensitivity of 0.027 µA·µM–1 and a low detection limit of 3.34 µM, as well as good stability and reproducibility.