Thickness Dependence of Oxygen Reduction Reaction Kinetics on Strontium-Substituted Lanthanum Manganese Perovskite Thin-Film Microelectrodes

Oxygen reduction reaction ͑ORR͒ kinetics was investigated on dense La 0.8 Sr 0.2 MnO 3 microelectrodes as a function of temperature and microelectrode thickness using electrochemical impedance spectroscopy.The surface oxygen exchange and mixed bulk/threephase-boundary ͑TPB͒ charge transfer process were found to control ORR kinetics at high and low temperatures, respectively.The transition temperature from the mixed bulk/TPB charge transfer control to surface oxygen exchange was found to be highly dependent on the microelectrode thickness ͑ϳ600°C for 65 nm vs ϳ800°C for 705 nm͒.These findings can be used to guide the design of electrodes that can operate at intermediate temperatures.