Promotion of carbon-supported platinum-ruthenium catalyst for electrodecomposition of methanol

A bimetallic catalyst consisting of a 7 wt % Pt₇₀-Ru ₃₀/C was prepared by the coprecipitation method and activated by a hydrogen reduction at 470 K. Physical characterization by TPR indicated that Pt atoms in the bimetallic crystallites deposited on freshly prepared catalysts tended to segregate to the crystallite surface during the activation. Catalytic activity of activated catalysts was examined by CV for oxidation of methanol. Current density obtained from the bimetallic catalyst was found to be enhanced by a combination of physical promotion with CeO₂ and chemical treatment of oxidation. The extent of enhancement varied with the loading of CeO₂ promoter and the temperature of oxidation treatment. A dramatic (370%) increase in the current density resulted from a promotion of 15% CeO ₂ and an oxidation treatment at 570 K. Models for changes of the physical structure of deposited bimetallic crystallites on the CeO₂ promotion and the oxidation treatment are proposed on the basis of the results presented here.