Carbohydrate electro-oxidation on chemically prepared MnO2

Oxidation of dextrose and fructose on MnO2/Pt electrodes prepared by solution phase comproportionation reaction between Mn(II) and Mn(VII) was studied using cyclic voltammetry, chronopotentiometry, steady state polarization and Fehling titration. The deposit was characterized by SEM, EDAX, IR spectrum and emf measurements. Cyclic voltammograms and chronopotentiograms indicate a catalytic EC mechanism to be operative with electrogeneration of Mn(V) as the primary electrochemical process. On this basis a mathematical model was set up to analyse the electrochemical data. The enhanced ease of oxidation of fructose with respect to dextrose was explained by considering the cyclic structures of the carbohydrates. Important role of OH groups in determining the current efficiency of CO group oxidation was pointed out.