Electrochemical Properties of Barium Cerate Doped with Zinc for Methanol Oxidation

Barium cerate and its zinc doped series, BaCe/sub 1-x/Zn/sub x/O/sub 3/ with 0.02 <= x <= 0.16, were synthesized using ammonia as a co-precipitant. The influence of zinc on phase and morphology was characterized using XRD and SEM, respectively. XRD revealed orthorhombic crystallinity for x= 0 to 14 mol% but distorted hexagonal phase for x = 16 mol%. SEM images revealed homogeneity of synthesized powders. The synthesized materials were then tested for their function as electrocatalyst for model analyte, methanol. Methanol electro-oxidation in acidic media was studied by modifying platinum electrode with BaCeO/sub 3/ materials using cyclic voltammetry. Kinetic (k/sub s,h/, D/sub o/) and thermodynamic parameters (E/sub a/, delta G, delta H, delta S) were estimated for methanol electroxidation. The deduced value of diffusion coefficient of order of 10/sup -10/ cm/sup 2/ s/sup -1/ indicated faster kinetics of methanol oxidation using BaCeO/sub 3/ than zinc doped sample in H/sub 2/SO/sub 4/ medium. The increasing temperature and methanol concentration enhanced the peak currents which pointed to the suitability of these materials as electrocatalysts. The stability and catalytic activity of these materials at various temperatures also aided to their potentiality in PEMFC application. (author)