STUDY OF THE NICKEL-BASED CHEMICALLY-MODIFIED ELECTRODE OBTAINED BY ELECTROCHEMICAL DEPOSITION OF AN NI-II-TETRAMETHYL-DIBENZO-TETRAAZA [14] ANNULENE COMPLEX - REDOX CATALYSIS OF CARBOHYDRATES IN ALKALINE-SOLUTIONS .2.

The electrochemical treatment of an electropolymerized (Ni(II)L)(n) thin film (where L represents 5,7,12,14-tetramethyl-dibenzo[b, i]-1,4,8,11-tetraaza [14] annulene) gives rise to al nickel-based catalytic deposit on conducting substrates [glassy carbon (GC), platinum, or gold electrodes], which shows strong similarities to the nickel hydroxide electrode. The effect of potential cycling on surface composition, chemical status, and morphology of this nickel-based chemically modified electrode (Ni-CME) has been investigated by cyclic voltammetry (CV) [1], X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. XPS analysis was very useful for characterizing the chemical changes in the nickel coordination caused by electrochemical treatments in alkaline solution. The featureless surface of the as-prepared GC/(Ni(II)L)(n) film compared with the fractal nature of the GC/Ni-CME was revealed by electron micrographs. The Ni-CME exhibits high electrocatalytic activity towards the oxidation of carbohydrates in alkaline solution. The electrooxidation capability of the Ni-CME is highlighted by the amperometric detection of sugars after anion-exchange liquid chromatographic separations with alkaline mobile phases.