Measurement of Oxygen Exchange Kinetics on Thin-Film La[sub 0.6]Sr[sub 0.4]CoO[sub 3−δ] Using Nonlinear Electrochemical Impedance Spectroscopy

In order to probe the mechanism of reduction on mixed-conducting oxides, we have measured the nonlinear harmonic impedance response of a dense thin-film electrode of . By combining a well-defined geometry with detection of small nonlinear harmonics, this approach reveals the nonlinear rate law governing reduction/oxidation. Comparison to various models based on nonequilibrium thermodynamics suggests that reduction on is limited by dissociative adsorption. To the authors' knowledge, this is the first isolation of the full nonlinear rate law governing exchange on a perovskite oxide.