Preparation, electrochemical properties and electrocatalytic activity of Zn-substituted tungstoborate modified electrode.

3-Aminopropyltrimethoxysilane (APTMS) was covalently grafted on a glassy carbon electrode (GCE) by silicon-oxygen bonds formation. The APTMS-modified GCE was used as a suitable charged substrate to fabricate Keggin Zn-substituted tungstoborate (BW11Zn)-consisting monolayer film through layer-by-layer assembly based on the electrostatic attraction. This modification strategy is proven to be a general one suitable for anchoring many kinds of POMs on the APTMS-modified GCE. The APTMS/BW11Zn film obtained on GCE is electrochemically active in acid aqueous solutions and exhibited three pairs of well defined, stable and quasi-reversible cyclic voltammetry peaks in the pH range 0-2. The anodic and cathodic peak currents are linearly proportional to the scan rate in the 200-1000 mV s(-1), indicating a surface confined electrode process. The formal potentials of BW11Zn film, E0 versus saturated calomel electrode (SCE), are -0.27, -0.43, -0.55 V in pH 1 H2SO4 solution and changed linearly with the slope of 44, 63, and 60 mV/pH in the pH range 0-2, respectively. The BW11Zn/APTMS/GC electrode shows good catalytic activity for the reduction of BrO3-, NO2- and H2O2.