Synthesis, activation and electrochemical study of platinum and platinum-based bimetallic nanoparticles for anode catalysts of direct methanol fuel cells (DMFCs)

Carbon-supported Pt and Pt-based bimetallic nanoparticles are active anode catalysts for DMFCs. It has been demonstrated that the catalytic activity of particles is strongly dependent on the size, shape, composition and size-distribution of particles. In this dissertation, the capping agents-based colloidal method was employed to synthesize Pt, Pt/Ru, Pt/Sn and Pt/Re nanoparticles with narrow size distribution. Controlling the particle size and composition was achieved by simply varying the amount of capping agents and the molar ratio of precursors. The as-prepared particles had a narrow size distribution and could be dispersed in hydrocarbon solvents. More significantly, a series of non-thermal or low-temperature treatments were successfully devised to activate the catalytic activity of the as-prepared particles, without inducing particle sintering and oxidation. The activity of nanoparticle catalysts was characterized by cylic voltammetry and CO stripping experiments. It was found that the carbon-supported nanoparticles were catalytically active for both methanol and CO oxidaion, and the activity of particles were shown to be size- and composition-dependent. In addition, the Pt-based bimetallic particles showed a higher CO-tolerance compared with pure Pt particles, due to the "bifuctional mechanism", and these bimetallic particles could be potentially used as CO-tolerant anode catalysts in fuel cell technology.