Catalytic oxidation of reduced nicotinamide adenine dinucleotide at a microband 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 of the resulting nickel hexacyanoferrate films indicate the presence of a couple of redox peaks which correspond to the hexacyanoferrate(II/III) redox couple. The nickel hexacyanoferrate modified microband gold electrode shows an excellent electrocatalytic activity for oxidation of reduced nicotinamide adenine dinucleotide (NADH) in phosphate buffer solution (pH 7.0), with an overpotential ca. 340 mV lower than that of 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 determined using a rotating disk electrode. The further experimental results show that the rate constant decreases with increasing NADH concentration. The mechanism of the oxidation of NADH catalyzed by the nickel hexacyanoferrate modified gold electrode is discussed.