The voltammetry of the aqueous two-electron reduction of the phenothiazine dye methylene green, known to be passivating at platinum electrodes, is reported under simultaneous activation with each of the following techniques: thermal activation in the temperature range 15-80°C, pulsed microwave activation with a modified 800 W, 2.45 GHz domestic microwave oven, 10 Hz pulsed laser activation with a Nd:YAG laser at 532 nm, sonication, or ultrasonic activation where a 20 kHz ultrasonic horn probe is employed to generate an aqueous/ organic solvent emulsion. The relative merits of the five methodologies are compared and discussed in terms of surface activation and cleaning, mass-transport enhancement, and reduction mechanism elucidation. Comparisons are also drawn with the voltammetry of methylene blue, a dye of the same family. This is the first full report of both the effects of microwave heating on surface redox electrochemistry and of the sonoemulsion technique.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry