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

Abstract

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 found to give Pd nanoparticles (~5nm). 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 dry methanol with intimate mixtures of PdOx+CuOx and PdOx+AgNO3. The electrochemical properties of the porous unsupported electrodes, prepared from these materials, in alkaline solutions, were investigated by cyclic voltammetry and steady-state polarization measurements. Various processes taking place during potential scanning in the presence and absence of methanol in 6m KOH solution are␣discussed. Steady-state polarization data indicate that the methanol oxidation reaction (MOR) activity decreases with incorporation of Cu and Ag into the Pd lattice. The extent of decrease in the MOR activity is less for Cu ad dition than for Ag addition.