CATALYTIC-OXIDATION OF REDUCED NICOTINAMIDE ADENINE-DINUCLEOTIDE AT AMICROBAND GOLD ELECTRODE MODIFIED WITH NICKEL HEXACYANOFERRATE

Nickel hexacyanoferrate films have been deposited on the surface of a microband gold electrode by cyclic voltammetry. Cyclic voltammograms o f the resulting nickel hexacyanoferrate films indicate the presence of a couple of redox peaks which correspond to the hexacyanoferrate(II/I II) redox couple. The nickel hexacyanoferrate modified microband gold electrode shows an excellent electrocatalytic activity for oxidation o f reduced nicotinamide adenine dinucleotide (NADH) in phosphate buffer solution (pH 7.0), with an overpotential ca. 340 mV lower than that o f the bare electrode. The steady-state current increases linearly with NADH concentration in the range of 0.5-8.0 mmol/l. The catalytic rate constant of the modified electrode for the oxidation of NADH is deter mined using a rotating disk electrode. The further experimental result s show that the rate constant decreases with increasing NADH concentra tion. The mechanism of the oxidation of NADH catalyzed by the nickel h exacyanoferrate modified gold electrode is discussed.