Cx. Cai et al., COBALT HEXACYANOFERRATE MODIFIED MICROBAND GOLD ELECTRODE AND ITS ELECTROCATALYTIC ACTIVITY FOR OXIDATION OF NADH, Journal of electroanalytical chemistry [1992], 397(1-2), 1995, pp. 185-190
A stable electroactive thin film of cobalt hexacyanoferrate (CoHCF) wa
s electrochemically deposited on the surface of a microband gold elect
rode. The cyclic voltammograms of CoHCF film indicate the presence of
two redox peaks corresponding to the hexacyanoferrate(II/III) redox co
uple. The electrochemical behaviour of CoHCF is related to the concent
ration of supporting electrolyte and counter-ions. The modified electr
ode shows excellent electrocatalytic activity towards the oxidation of
reduced nicotinamide adenine dinucleotide (NADH) in phosphate buffer
solution (pH 7.0), with an overpotential ca.310-370 mV lower than that
of the bare microband cold electrode. The catalytic peak current is p
roportional to NADH concentration in the range 0.5-6.0 mM with a corre
lation coefficient of 0.98. The catalytic rate constant of the modifie
d electrode for the oxidation of NADH is determined using a rotating-d
isc electrode. The mechanism of the oxidation of NADH catalysed by the
electrode is discussed.