Electrocatalytic reduction of hydrogen peroxide on modified graphite electrodes: application to the development of glucose biosensors

Abstract

The electrocatalytic activities of a series of compact graphites modified with microquantities of platinum metals (Pd or Pt+Pd) towards the electrochemical reduction of hydrogen peroxide were characterised. Operational parameters such as the optimal working potential, the influence of temperature and the resulting electrode characteristics were examined. The benefits of using graphite modified with Pt+Pd (mixture ratio 30%:70%) as the basic transducer in a glucose biosensor with improved sensitivity were demonstrated. It was proven that, under the working conditions chosen, the selected electrode (whether bare or covered with an enzyme layer) did not respond to any glutathione, uric acid or ascorbic acid (which all normally occur in biological fluids) present.

Electrocatalytic Reduction of Hydrogen Peroxide on Palladium-Gold Codeposits on Glassy Carbon: Applications to the Design of Interference-Free Glucose Biosensor

“…The value of the apparent Michaelis constant K app M = 405 μM was found to be 1.8 times as low as the one determined at 25 • C. In Table 3, the operational characteristics of the examined electrode were compared to the ones of the glucose oxidase enzyme electrode, determined through immobilization of GOx on porous graphite (GMZ), modified from a solution containing Pd and Au mixed in a ratio of 70% : 30% [10]. The glucose oxidase enzyme electrodes will be referred to as follows:…”

“…On it, by immobilizing GOx in accordance with a previously reported procedure [10], a new glucose oxidase enzyme electrode was developed. The possibility to determine quantitatively glucose at potentials of −100 and −50 mV in a phosphate-citrate buffer pH 7.0, at temperatures of 25 • C and 35 • C (Table 2), was examined.…”

“…Our research has shown that highly porous graphite materials, modified through potentiostatic deposition of Pt, Pd, and mixtures of (Pd+Pt) and (Pd+Au) in varied proportions, prove to be effective electrocatalysts for the reduction of hydrogen peroxide at low working potentials [9,10]. In addition, modified graphites were characterised with a simple modification protocol, high operational stability over a wide pH-range, and high operational stability with retaining catalytic activity for over 1 year that motivated us to use them as electrochemical transducers in the design of amperometric biosensors based on the electroreduction of hydrogen peroxide.…”

“…Alternatively, reducing electrochemically H 2 O 2 at low working potentials (usually around 0 V versus Ag/AgCl) [5], where interfering substances are electrochemically inert, allows for a much more selective assay of the analyte. In respect to studies on the surface modified with micro-and nanostructures carbonaceous electrodes as efficient electrocatalysts of hydrogen peroxide, both oxidation and reduction [6][7][8][9][10][11][12][13] are currently on high demand.…”

“…Various types of carbonaceous materials have been investigated most often as modified electrodes for determining H 2 O 2 : graphite [6,14], glassy carbon [7,8,10,[15][16][17][18][19], carbon-paste electrodes [20,21], carbon nanotubes [22][23][24], and so forth. With these electrodes, the selectivity of the electrochemical response to hydrogen peroxide is improved by using different catalytically active modification components: transition metals and their oxides [15,21], platinum metals, dispersed on their own or mixed with other platinum metals [7,25], and with nanostructured composite films [8,26].…”