ISSN:
1572-8838
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Electrical Engineering, Measurement and Control Technology
Notes:
Abstract A novel electrochemical method for the extraction of pure oxygen from air is described. The system consists of an undivided cell with a nickel anode, a carbon–polytetrafluoroethylene (CP) air-fed cathode and a KOH+HO2- solution as electrolyte. In such a Ni–CP cell, oxygen from the air is reduced in the cathode to form HO2- via a two-electron process, whereas anodic generation of oxygen gas can take place by the two-electron oxidation of HO2- and/or the four-electron oxidation of OH- of the medium. Gas chromatography confirmed that the oxygen produced from cells operating up to 190mAcm-2 does not contain hydrogen, as expected if cathodic reduction of H2O does not take place. The presence of HO2- causes a decrease in energy consumption of the cell, since it is easier to oxidize than OH-. Ni–CP cells containing solutions with concentrations of OH- to 2.4moldm-3 and HO2- from 0.1 to 0.5moldm-3 are stable at 25°C for voltages to about 1.0V. These cells work in a steady state in which the same number of moles of HO2- ions electrogenerated at the cathode are also anodically decomposed at the anode, without OH- oxidation. In this state, the oxygen consumed in the cathode is anodically generated and extraction of oxygen from air occurs by a two-electron process. Energy consumptions between 1.710kWhkg-1 O2 and 1.224kWhkg-1 O2 are obtained for bielectronic stable cells operating at 100mAcm-2 and at temperatures between 25°C and 45°C, which are significantly lower than those reported for previous electrochemical oxygen generators based on the anodic decomposition of OH-.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1026475117836
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