Pd-based, Direct Methanol Fuel Cell Cathode Catalyst Research

Electrocatalyst is one of the key materials in direct methanol fuel cells and strongly affect the activity, stability and durability of DMFC. The studies of cathodic electrocatalysts with low cost and methanol tolerant have important value in the theory and application for DMFCs.This thesis mainly investigated the preparation of Pd/C, PdFe/C, PdCo/C cathodic catalysts and their electrocatalytic performance on the oxygen reduction reaction (ORR). The main results obtained are as follows:1. Pd/C electrocatalyst is prepared by the thermal decomposition of Pd(Ac)2 with using 1-octadecene as the solvent and oleic acid(OA) and oleylamine(OLA) as surfactants. The produced as-prepared Pd/C electrocatalyst is characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and the electrocatalytic performance on the ORR are tested with cyclic voltammetry. The Pd NPs size in the Pd/C catalyst is about 4.5 nm, and owns high dispersion. The CV studies show that as-prepared Pd/C electrocatalyst has higher electrocatalytic activity for the oxygen reduction than that of Pd/C electrocatalyst prepared with liquid reduction method.2. Carbon-supported PdFe bimetallic NPs with relatively small particle size and single-phase fcc disordered structure was prepared by direct thermal decomposition method of metallic acetate salt at 300℃. The obtained PdFe/C electrocatalyst shows an excellent electrocatalytic activity for the ORR, which is likely attributed to the inhibition of generation of surface palladium oxides and the change of the Pd-Pd mean interatomic distance. Importantly, the obtained PdFe/C electrocatalyst contains no any impurity ions since metallic acetate salts are used as reaction precursors. Consequently, the tedious wash post-treatment of catalyst is effectively avoided.3. Carbon-supported PdCo bimetallic NPs with relatively small particle size and single-phase fcc disordered structure has been prepared by direct thermal decomposition method of metallic acetate salt at 200℃. The obtained PdCo/C electrocatalyst shows an excellent electrocatalytic activity for the ORR, which is likely attributed to the change of Pd-Pd mean interatomic diatance.