A sensitive mercury-free lead (Pb 2þ ) sensor has been proposed based on an ordered mesoporous carbon and Nafion composite film (OMC/Nafion) coated glassy carbon electrode. The analysis of Pb 2þ using anodic stripping voltammetry (ASV) includes two steps. Pb 2þ ions are firstly reduced and deposited on the electrode surface in a Pb 2þ solution (10 mL) during a preconcentration step biased at À 1.0 V, followed by a measurement step by differential pulse voltammetry (DPV) within the potential range of À 0.8 to À 0.3 V (scan rate: 20 mV/s, frequency: 20 Hz, amplitude: 50 mV, pulse width: 50 ms). Linear calibration curve was found to be from 20 nM to 2 mM for Pb 2þ with a sensitivity of 17.4 AE 1.38 mA/mM after a 5-min of preconcentration. The detection limit was estimated to be around 4.60 AE 0.12 nM at the signal to noise ratio of 3. Reproducibility (RSD%) was found to be 3.0% for a single sensor with eight measurements and 4.3% for five sensors prepared with identical procedures. The practical application of the proposed lead sensor was verified by determination of trace level of Pb 2þ in tap water sample.

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Nanosized Prussian blue (PB) particles were synthesized with a chemical reduction method and then the PB nanoparticles were assembled on the surface of multiwall carbon nanotubes modified glassy carbon electrode (PB/ MWNTs/GCE). The results showed that the PB/MWNTs nanocomposite exhibits a remarkably improved catalytic activity towards the reduction of hydrogen peroxide. Glucose oxidase (GOD) was immobilized on the PB/MWNTs platform by an electrochemically polymerized o-phenylenediamine (OPD) film to construct an amperometric glucose biosensor. The biosensor exhibited a wide linear response up to 8 mM with a low detection limit of 12.7 mM (S/N ¼ 3). The Michaelis -Menten constant K m and the maximum current i max of the biosensor were 18.0 mM and 4.68 mA, respectively. The selectivity and stability of the biosensor were also investigated.

Two new transition‐metal (TM) complex salts of the Wells‐Dawson polyanion: [Cu(2,2′‐bpy)3]2[Cu(2,2′‐bpy)2]2[P2W18O62] (1) and [2,2′‐bpy]8[Fe(2,2′‐bpy)3]8[P2W18O62]4·9H2O (2) (2,2′‐bpy = 2,2′‐bipyridine), have been synthesized under hydrothermal conditions by using pre‐prepared α‐K6P2W18O62·15H2O as a precursor. Crystal data for compound 1: monoclinic, space group C2/c, a = 20.722(4) Å, b = 21.988(4) Å, c = 29.614(6) Å, β = 104.32(3)°, V = 13074(5) Å3, Z = 4; for compound 2: triclinic, space group ${\rm P}{\bar 1}$, a = 15.804(3) Å, b = 27.519(6) Å, c = 27.566(6) Å, α = 72.71(3)°, β = 89.94(3)°, γ = 89.90(3)°, V = 11447(5) Å3, Z = 1. Compounds 1 and 2 have been characterized by single‐crystal X‐ray diffraction, IR spectra, thermogravimetric analysis, XPS spectra and cyclic voltammetry. The two compounds were used as solid bulk modifiers to fabricate bulk‐modified carbon paste electrodes (1‐, 2‐CPE). The electrochemical behaviors of 1‐, 2‐CPE have been studied in detail. The redox behavior of the parent Wells‐Dawson type cluster was maintained completely in compounds 1 and 2.

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An inorganic‐organic hybrid solid (H6/5bppy)5[P2W18O62]·4.5H2O (1) (bppy = 4‐(5‐(4‐bromophenyl)pyridin‐2‐yl)pyridine) was hydrothermally synthesized by using pre‐constructed Wells‐Dawson type salt α‐K6P2W18O62·15H2O as inorganic moiety. The crystal structure keeps integrated and steady under the interactions together of aryl packing, hydrogen bonding and halogen bonding. X‐ray single crystal structure analysis reveals that compound 1 contains cavities with the sizes of about 6 × 8Å, in which H2O molecules are captured. The hybrid was used as a solid bulk modifier to fabricate a three‐dimensional bulk‐modified carbon paste electrode (1‐CPE) by direct mixing. The electrochemical and electrocatalytic behavior of the 1‐CPE has been studied in detail. The results exhibit that the redox ability of the Wells‐Dawson polyanions can be maintained in the hybrid solid, which has a good electrocatalytic activity toward the reduction of bromate and hydrogen peroxide. A hydrodynamic voltammetric experiment was performed to characterize the electrode as an amperometric sensor for the determination of hydrogen peroxide. The 1‐CPE showed long‐term stability and excellent reproducibility of surface renewal.