A NEW METHOD FOR THE PREPARATION OF HIGHLY DISPERSED METAL-CARBON CATALYST PD C CATALYST AND ITS PROPERTIES/

Highly dispersed Palladium/Carbon catalyst was prepared by the reducti on of PdI2 which was precipitated on the surface of activated carbon. The essential steps are: (I) the functionalization of the surface of t he carbon with preadsorption of I-; (II) the precipitation of Pd2+ on the carbon surface; (III) the reduction of PdI2 on the carbon surface. The effects of preadsorption of different halogen ions and the reduct ion of temperature on Pd particle size and the crystal structure were studied by transmission electron microscopy (TEM) and selected area di ffraction (SAD) methods. As a comparison, carbon oxidized with HNO3 wa s also used as support. The effects on particle size and crystal struc ture were also studied with TEM and SAD. The adsorption characteristic s of Pd2+ and halogen ions on the carbon were measured by an argentime try method. The results of the electrocatalytic reduction of oxygen sh owed that the catalysts prepared with this new method were more active than those prepared with the carbon preoxidation method.