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Study of Ruthenium-Promoted Pt Electrocatalyst: Chemical State and Stability of Ruthenium

Author: MaJunHong
Tutor: WangAnJie；XuBaiQing
School: Dalian University of Technology
Course: Industrial Catalysis
Keywords: Methanol Electro-oxidation Platinum electrocatalyst Ruthenium oxide hydrate Tungsten oxide Molybdenum oxide The stability of the catalyst
CLC: O643.36
Type: PhD thesis
Year: 2010
Downloads: 192
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Abstract


PtRu anode catalyst of the catalyst is by far the most effective direct methanol fuel cell (DMFC) what oxidation state of ruthenium in the actual electro-catalytic process to act as an effective Cocatalysis have not yet been clarified. Systematically investigated additives ruthenium chemical state of its co-catalyst performance relationship is undoubtedly of great significance for improving the catalytic activity of the Pt-based catalyst and to improve the performance of the DMFC. Prepared in the present work the series hungry aqueous nail oxide (RuO x H y) species Pt-(RuOxHy) m / MWCNTs catalyst (m Ru / Pt atomic ratio), the system of the composition of the catalyst (Ru / Pt atomic ratio), pretreatment factors such as the potential impact of the catalytic properties of hydrated ruthenium oxide to help a variety of ways and a stabilizing effect on the anode catalyst hydrated nail species in-depth exploration and research, the following main results: 1) Preparation of a Pt-step-by-step load ( RuO x H y) m / MWCNTs series electro-catalyst, the use of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, temperature-programmed reduction and thermal gravimetric analysis by means of the structure and composition of the catalyst system characterized. The results showed that the synthetic samples nails species are RuOxHy state exists to provide a basis as a separate to visits RuOxHy Cocatalysis. The contrast effects of cyclic voltammetry pretreatment of the catalytic properties of the electrode catalyst narrow potential (-0.20 to 0.46 V vs. SCE) and extended the potential range (-0.20 to 0.96 V vs. SCE), found RuOxHy effective in promoting CO on Pt oxidative removal of the catalyst, but it will also lead to a decline in Pt electrochemical active surface area. Narrow potential range of pre-treatment does not result in the loss of the dissolution of the RuOxHy, Pt-(RuOxHy) 0.10/MWCNTs showed the highest methanol oxidation activity for the corresponding Pt / MWCNTs 9 to 10 times. Expand the potential range of pretreatment cause obvious RuOxHy dissolution, the Pt-RuO x H y catalyst performance decreased significantly. Through modulation of preparation conditions (e.g.: MWCNTs pretreatment mode, the ruthenium precursor solution concentration, and RuOxHy the drying temperature, etc.), affect the Pt-RuO-the of HY catalyst performance and RuOxHy stability factors discussed. 2) found that the presence of a transition metal oxide (WOM, or MooM), can effectively improve the stability of the Pt-(RuOxHy) 0.10/MWCNTs catalyst RuOxHy. In the expansion potential range in the pretreatment process, the degree of dissolution of RuO x H y from Pt-RuOxHy/MWCNTs 70% significantly reduced to approximately 15% the Pt-RuOxHy-WOm/MWCNTs and Pt-RuOxHy-MoOm/MWCNTs of samples, Pt-RuO x H y The Pt -WOm/MWCNTs and Pt-RuOxHy-MoOm/MWCNTs of CO tolerance performance is significantly better than Pt-RuOxHy/MWCNTs methanol electro-oxidation of the intrinsic activity of more than 2 times the Pt-RuOxHy/MWCNTs. 3) found significantly better than the XC-72 carbon black load the Pt-RuOxHy sample RuOxHy stability in an acidic electrolyte the MWCNTs load the Pt-RuOxHy, samples. However, the introduction of the WOm or MoOm Pt-RuOxHy/XC on to further improve RuOxHy stability in an acidic electrolyte is not significant. These results indicate that, RuO x H y in acidic electrolytes the stability and WOm or closely related to the same vector type MoOm the RuOxHy stabilizing effect.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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