The Application Of Amorphous Pt Based Catalyst In Electrocatalytic Methanol Oxidation

Pt and Pt-based nanoparticles deposited on carbon supports dominate as anode catalysts for direct methanol fuel cells(DMFC) due to their high specific surface area, high mass activity and stability. However, the prohibitive cost, scarcity and eventual activity decay of Pt-based catalysts prevents the widespread use and commercialization of fuel cells. To overcome these issues requires a significant increase in the mass activity of Pt-based catalysts. Engineering of catalyst morphology and composition to reduce the usage of Pt offers a promising approach.Pt-based amorphous nanoparticles synthesized by chemical methods have rarely been explored for fuel cell electrocatalysts and offer an interesting avenue to obtain further improvement of Pt mass activity. Moreover, synthesis of nano-sized electrocatalyst in the desired ultrafine size range is an effective approach to improve the mass activity. Phosphorus, with its abundant valence electrons, when incorporated into the catalyst has significant effects on both magnetic and catalytic activity, resulting in ultrafine particles size.In this study, we developed a method to synthesize carbon supported ultrafine Pt-based nanoparticles with amorphous structure. The thesis consists of three parts as following:Part I The Effect of Pt P Nanoparticles Crystallinity in Electrocatalytic Methanol OxidationAmorphous Pt P nanoparticles supported on Vulcan carbon(Pt P a/C) were synthesized, followed by increasing degrees of heat treatment to obtain higher levels of crystallinity in the supported Pt P particles(Pt P-200/C, Pt P-300/C and Pt P-400/C). Structural and compositional analysis by various techniques allowed correlation between the structures of various Pt P states and their resultant catalytic methanol oxidation activity. The results of the electrochemical performance investigation showed that amorphous Pt P a/C has not only better catalytic activity for methanol oxidation but also stronger tolerance to carbon monoxide poisoning compared to the crystalline structure.Part II The Effect of Pt Ni P Nanoparticles Crystallinity in Electrocatalytic Methanol OxidationAmorphous Pt Ni P nanoparticles supported on Vulcan carbon(Pt Ni P a/C) were synthesized, followed by increasing degrees of heat treatment to obtain higher levels of crystallinity in the supported Pt Ni P particles(Pt Ni P-300/C, Pt Ni P-500/C and Pt Ni P-700/C). Structural and compositional analysis by various techniques allowed correlation between the structures of various Pt Ni P states and their resultant catalytic methanol oxidation activity. The results of the electrochemical performance investigation showed that amorphous Pt Ni P a/C has not only better catalytic activity for methanol oxidation but also stronger tolerance to carbon monoxide poisoning compared to the crystalline structure.Part III The Effect of Pt Ru Ni P Nanoparticles Crystallinity in Electrocatalytic Methanol OxidationAmorphous Pt Ru Ni P nanoparticles supported on Vulcan carbon(Pt Ru Ni P a/C) were synthesized, followed by increasing degrees of heat treatment to obtain higher levels of crystallinity in the supported Pt Ru Ni P particles(Pt Ru Ni P-300/C, Pt Ru Ni P-500/C and Pt Ru Ni P-700/C). Structural and compositional analysis by various techniques allowed correlation between the structures of various Pt Ru Ni P states and their resultant catalytic methanol oxidation activity. The results of the electrochemical performance investigation showed that the amorphous structures with medium-range disorder(Pt Ru Ni P-300/C) have not only better catalytic activity, but also better durability for methanol oxidation compared to the long-range disorder and medium-range order structure.