Carbon dioxide reduction current potential

A sensor based on this reaction scheme has been described by Hahn [37]. This is a Clark type sensor which operates using a double pulse method. The first pulse is to a potential at which the reduction of oxygen occurs at its diffusion limited rate. The integrated current is used as a measure of oxygen concentration. The second pulse is to a potential where the superoxide ion is oxidised back to oxygen. In the absence of COj the integrated current should match that of the forward pulse. When CO2 is present the reverse pulse is diminished. The difference between the two pulses is therefore a measure of the amount of carbon dioxide present. The interested reader is referred to the review by Hahn for further details of this system. 

An increase of the current density of the O2 reduction at constant potential with the micropore volume was reported for porous carbon electrodes in alkaline solutions by Schwabe and coworkers [10]. The activation of the electrodes with carbon dioxide or water vapor increased the value of A and produced a certain degree of hydrophobicity. 

The electrochemical Incineration of synthetic sewage waste in 12M H2SO4 or urine was studied by Kaba et al. [30]. At a potential of 1.8 V vs. NHE, a 95% reduction in total organic carbon (TOC) occurred on lead dioxide electrodes after 90 h of operation. The addition of a Ce /Ce redox couple to the electrolyte caused a fivefold increase in the current density but only a 1.5-fold increase in the destruction rate. The use of ultrasound also resulted in an increase in the current density and destruction rate. 

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