Enhanced electrocatalytic activity for oxygen reduction over carbon-supported LaMnO3 prepared by reverse micelle method

Carbon-supported LaMnO3 was prepared by a reverse micelle method. Aqueous s olutions of nitrates of La and Mn (A) and N(CH3)(4) OH (B) were brought int o reverse micelle solutions by using NP-5 surfactant and cyclohexane solven t, respectively. Carbon powder was mixed with solution A and B stepwise, an d the resulting suspension was subjected to a series of treatments to colle ct carbon powder loaded with a precursor of the oxide, which was calcined a t 600 degrees C under N-2 flow to convert the precursor to LaMnO3. The gas diffusion-type oxygen electrode using the carbon- supported oxide thus prep ared showed surprisingly high electrocatalytic activity for oxygen reductio n. The current density was as high as 300 mA cm(-2) at -80 mV vs. Hg/HgO in 8 M KOH at 60 degrees C under air flow. This performance was maintained un disturbed for the 140 h testing period. (C) 1998 The Electrochemical Societ y. S1099-0062(98)08-016-X. All rights reserved.