The influence of a new fabrication procedure on the catalytic activity of ruthenium-selenium catalysts

A new procedure has been introduced to enhance catalytic activity of ruthenium-selenium electro-catalysts for oxygen reduction, in which materials are treated under hydrogen atmosphere at elevated temperatures. The characterisation using scanning electron microscopy, energy dispersive spectroscopy or energy dispersive X-ray spectroscopy exhibited that the treatment at 400 degrees C made catalysts denser while their porous nature remained, led to a good degree of crystallinity and an optimum Se:Ru ratio. The half cell test confirms feasibility of the new procedure; the catalyst treated at 400 degrees C gave the highest reduction current (55.9 mA cm(-2) at -0.4 V) and a low methanol oxidation effect coefficient (3.8%). The direct methanol fuel cell with the RuSe 400 degrees C cathode catalyst (2 mg RuSe cm(-2)) generated a power density of 33.8 mW cm(-2) using 2 M methanol and 2 bar oxygen at 90 degrees C. The new procedure produced the catalysts with low decay rates. The best sample was compared to the Pt and to the reported ruthenium-selenium catalyst. Possible reasons for the observations are discussed. (c) 2006 Elsevier Ltd. All rights reserved.