Effects of incorporation of Cu and Ag in Pd on electrochemical oxidation of methanol in alkaline solution

Pd fine particles were prepared by heterogeneous reaction of PdOx with dry methanol as well as by the NaBH4 reduction method. The former method was fo und to give Pd nanoparticles (similar to 5 nm). Similarly f.c.c. structured , single phase nanoparticles of alloy compositions Pd0.8Cu0.2, Pd0.5Cu0.5, Pd0.8Ag0.2 and Pd0.5Ag0.5 were prepared by the heterogeneous reaction of dr y methanol with intimate mixtures of PdOx + CuOx and PdOx + AgNO3. The elec trochemical properties of the porous unsupported electrodes, prepared from these materials, in alkaline solutions, were investigated by cyclic voltamm etry and steady-state polarization measurements. Various processes taking p lace during potential scanning in the presence and absence of methanol in 6 M KOH solution are discussed. Steady-state polarization data indicate that the methanol oxidation reaction (MOR) activity decreases with incorporatio n of Cu and Ag into the Pd lattice. The extent of decrease in the MOR activ ity is less for Cu addition than for Ag addition.