(702a) Novel Quaternary Pt-Ru-Ni-Ti Alloy System for Direct Methanol Fuel Cell Electrocatalyst

Direct methanol fuel cells (DMFC) are of interest as suitable power sources for consumer electronic devices as well as remote and auxiliary power units for transportation. The main advantage of DMFC is the use of liquid methanol rather than gaseous hydrogen as the operating fuel used in the hydrogen fueled proton exchange membrane fuel cell (PEM). The relatively sluggish kinetics of the electrochemical reactions occurring on the catalyst layers at the electrode surface combined with the methanol crossover to the cathode compartment reduces the power density of the DMFC. There is therefore a critical need to research and develop new and improved electro-catalysts with higher catalytic activity in order to enhance the efficiency and power density of DMFC, while lowering the precious metal loadings to realize the much desired cost savings to match the performance. Currently, Pt-Ru alloy of nominal composition Pt-50at.% Ru is considered the most suitable catalyst composition yielding the best catalytic activity and is hence widely recognized as the anode catalyst for use in DMFCs. Improved anode catalysts can be obtained by synthesizing high surface area Pt-Ru based alloy catalysts combined with engineered proper alloy design by modifying the chemical composition of the alloy, and doping or alloying with other elements onto the catalyst structure. It has been proposed that addition of other alloying elements could reduce material loss during cycling and particle ripening. Ni-Zr and Ni-Ti have been previously shown to be electrochemically active and stable under anode conditions. In the present work, we report bulk synthesis of nanocrystalline Pt-Ru-Ni-Ti based quaternary alloys, for use as DMFC anodes, by a facile wet chemical synthesis route. X-ray results show complete alloying and formation of phase pure Pt(Ru,Ni,Ti) solid solution, and also nanocrystalline nature of the alloy. Alloy materials have been shown to have high BET surface areas (> 200 m²/g). Cyclic voltammetry and polarization results indicate that the nano-crystalline Pt-Ru-Ni-Ti alloy of suitable compositions, possessing good chemical homogeneity, reveals excellent catalytic activity, demonstrating the potential of the Pt-Ru-Ni-Ti based electrocatalysts for direct methanol fuel cells.