Instabilidades dinâmicas na eletro-oxidação de D-(+)-glicose sobre ouro

The study of gold as electrocatalyst material towards the electro-oxidation of alcohols and sugars in alkaline medium is of special significance due to its high catalytic activity. In this work, were port the emergence of kinetic instabilities in the form of oscillating reaction rates observed during the electro-oxidation of D-(+)-glucose on polycrystalline gold in alkaline medium. The system was studied by means of cyclic voltammetry, chronoamperometry, chronopotentiometry, and Electrochemical Impedance Spectroscopy (EIS). EIS results confirm the presence of a negative differential resistance (NDR) in two different potential regions. Oscillatory behavior was observed under galvanostatic, potentiostatic control modes and in a wide parameter range. Figure 1 exemplifies typical oscillatory time-series recorded during the electro-oxidation of D-(+)-glucose on gold. The occurrence of mixed-mode potential oscillations, cf. Fig. 1 (a), suggests the diversity of surface-poisoning species. Importantly, this is apparently the first data evidencing the emergence of oscillatory kinetics during the electro-oxidation of carbonaceous species on gold surfaces.