Electrocogeneration of hydrogen peroxide: Confocal and potentiostatic investigations of hydrogen peroxide formation in a direct methanol fuel cell

This work aims to fulfil some of the critical challenges associated with the electrochemical processes in commercialisation of an electrocogeneration direct methanol fuel cell: the understanding of the formation, decomposition and removal of hydrogen peroxide at the cathodic chamber. The better understanding of operating conditions on improving the electrocogeneration performance is also valuable for developing an optimal operating condition that enhances electrocogeneration activity. The production and removal of hydrogen peroxide are investigated by sensing the fluorescence signal in the cathodic chamber using confocal microscopy. It is found that the higher production of hydrogen peroxide promotes the intensity but reduces the cell potential due to the depletion of fresh reactant and the accumulation of hydrogen peroxide. Consequently, hydrogen peroxide should be removed efficiently in order to maintain the cell performance. The three-dimensional distribution and concentration of hydrogen peroxide are quantified at various operating potentials using fluorescence mapping, which is a correlation between the fluorescence signal and the concentration of hydrogen peroxide. The simultaneous fluorescence and potentiostatic investigations indicate that the electrocogeneration process is improved significantly by decreasing the cell potentials; the current efficiencies of 85.00, 64.78 and 51.13% are obtained at the operating potentials of 300, 400 and 550 mV respectively.