Electrochemical oxidation of H{sub 2} and CO in a H{sub 2}-H{sub 2}O-CO-CO{sub 2} systems at the interface of a Ni-YSZ cermet electrode and YSZ electrolyte
The electrochemical oxidation of H{sub 2} and CO in a H{sub 2}-H{sub 2}O-CO-CO{sub 2} system at the interface of a porous Ni-yttria stabilized zirconia (YSZ) cermet electrode and YSZ electrolyte has been studied using complex-impedance spectroscopy and direct-current polarization measurements of 1,023 and 1,273 K under a constant oxygen partial pressure. The polarization resistance increased when the CO concentration ratio, p{sub CO}[p{sub H{sub 2}} + p{sub CO}], exceeded 0.2 and 0.5 at 1,023 and 1273 K, respectively. The electrochemical oxidation rate of H{sub 2} was 1.9--2.3 times and 2.3--3.1 times higher than that of CO at 1,023 and 1,273 K, respectively, and the water-gas shift reaction was found to be much faster than the electrode reaction at both temperatures. An equivalent-circuit analysis of the complex-impedance spectra suggested that the lower electrochemical oxidation rate of CO (compared to H{sub 2}) was caused mainly by the larger diffusion resistance of CO than H{sub 2} on the electrode surface at 1,023 K, and by both the larger surface diffusion resistance and charge-transfer resistance at 1,273 K.
- Research Organization:
- Tokyo Gas Co., Ltd. (JP)
- OSTI ID:
- 20080556
- Journal Information:
- Journal of the Electrochemical Society, Vol. 147, Issue 5; Other Information: PBD: May 2000; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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