Platinum-Ruthenium Heterogeneous Catalytic Anodes Prepared by Atomic Layer Deposition for Use in Direct Methanol Solid Oxide Fuel Cells

Abstract

Heterogeneous Pt-Ru catalysts are synthesized by atomic layer deposition (ALD) of Ru onto a porous Pt mesh and employed as the anode in direct methanol solid oxide fuel cells (DMSOFCs). The degree of Rti coverage is controlled by the number of deposition cycles employed in catalyst preparation; samples are prepared using 50, 100, 200, 300, and 400 cycles. The dispersed nature of the ALD Ru coating is confirmed by auger electron spectroscopy and high resolution transmission electron microscopy. DMSOFC performance is measured at several temperatures between 300 and 450 degrees C. Optimal ALD Ru coverage results in DMSOFC power and electrode impedance values close to ones from SOFCs with Pt electrodes running on hydrogen. Thermal stability is also improved significantly, preventing agglomeration of the Pt mesh. X-ray photoelectron spectroscopy is used to analyze the chemical properties of the surface and confirms that increased ALD Ru coverage results in a dramatic reduction in the amount of surface bound carbon monoxide (CO) present after cell operation. This suggests that improved anode kinetics resulted from the reduction of the CO-passivated Pt layer.