Hiroo Numata1, Akihiko Momma2, Ki-ichiro Asako3 and Shiro Haruyama1
1Department of Metallurgical Engineering, Faculty of Engineering, Tokyo Institute of Technology, Tokyo
The kinetics of the O2-/1/2O2 on Pt, Au and Pd electlodes in NaCl-KCl melt at 1023 K have been studied with the galvanostatic double pulse and a.c. impedance methods. The cathodic polarization curves on these electrodes under different partial pressures of oxygen exhibited a diffusion limited current and the cathodic reduction of oxygen proceeds via a two-step mechanism. The rate of the rapid charge transfer step measured with the galvanostatic double pulse method was of the order of 104 A • m-2. Cole-Cole plot of the impedance of the oxygen electrode exhibited a semicircle at high frequencies and a Warburg behavior at low frequencies. The exchange current obtained from the diameter of the semicircle was two orders of magnitude less than that obtained from the galvanostatic double pulse method and probably corresponds to that of the slower reaction step.
electrochemical study, kinetics, oxygen electrode-reaction, galvanostatic double pulse method, alternate current impedance-method, chlorides melt, platinum, gold, palladium
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