Modified electrode with hydrotalcite-like materials and their response during electrochemical oxidation of blue 69

In order to evaluate the electrocatalytic properties, Mg/Al and Mg/Ca/Al hydrotalcite-like materials (LDHs) and their corresponding mixed oxide were immersed in a carbon paste electrode matrix to obtain the so-called modified carbon paste electrode (MCPE). Previous to preparation of MCPE, LDH materials were characterized by different techniques, as XRD, FTIR and BET analysis. The electrochemical response of the electrodes was characterized in neutral conditions using reactive blue 69 dye as a probe molecule. Linear sweep voltammetry (LSV), cyclic voltammetry (CV), multi-sweep cyclic voltammetry (MSCV) and open circuit potential transient techniques were employed. Different current magnitudes in the oxygen evolution reaction (OER) were found as a function of thermal treatment and supporting electrolyte (pH). On the other hand, in a solution containing 250 ppm of the probe molecule at neutral pH, peaks attributed to blue 69 oxidation were found at ca. 0.65 and 0.95 V/SCE. The presence of calcium, as additional divalent cation, and the rehydration of the mixed oxide, due to memory effect, have a positive performance, increasing the magnitude of the electrocatalytic process.