Effect of functionalized carbon as Pt electrocatalyst support on the methanol oxidation reaction (original) (raw)
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Carbon, 2006
Chemical modification of Carbon Vulcan XC-72R for fuel cell applications has been undertaken. Treated carbons were used as carriers for the deposition of Pt nanoparticles and used as electrocatalysts. The influence of the carbon treatment, as well as that of the Pt nanoparticles generation and their deposition route has been studied. The behaviour of the electrocatalysts in the CO and hydrogen oxidation reaction (HOR) has been studied. It was observed that carbon pre-treatment lead to difference behaviour in the CO oxidation reaction compared with the performance over non treated supports. In this way, CO oxidation was controlled by the nature of the support rather than by the nature of the Pt particles alone.
Methanol electrooxidation on PtRu nanoparticles supported on functionalised carbon black
Catalysis Today, 2006
The effect of the preparation method of PtRu electrocatalysts and the chemical treatment of support on the performance for methanol electrooxidation has been studied. Carbon supported PtRu catalysts were synthesized from aqueous solution of H2PtCl6 and RuCl3 precursors by two different methods: colloidal (using NaHSO3) and impregnation. The carbon black Vulcan XC-72R was functionalised with H2O2 and HNO3. A commercial PtRu/C catalyst purchased from Johnson and Matthey was used as reference. The obtained electrocatalysts were characterized by XPS, XRD, TEM, EGA-MS, TGA and TXRF. Chronoamperometry in methanol and COads stripping experiments were conducted to check their electrocatalytic activity. Electrocatalysts obtained by the colloidal method and supported on functionalised carbon black with HNO3 and especially with H2O2, showed better performances (CO tolerance and superior methanol oxidation ability) than those obtained by the impregnation method and the commercial one.
Applied Catalysis B-environmental, 2017
In this work, a novel procedure to enhance the catalytic activity of Pt/C for the MOR by promoting surface Pt-Ru metal interactions is proposed. Vulcan is functionalized with home-prepared ruthenium (II) arene compound [(η 6-C 6 H 5 OCH 2 CH 2 OH)RuCl 2 ] 2 (Ru-dim) and labeled C Ru-dim. Then, Pt/C Ru-dim is synthesized by the polyol method. Also, Vulcan functionalized with RuCl 3. XH 2 O (Ru-com) and non-functionalized Vulcan are used to prepare Pt/C Ru-com and Pt/C, respectively. The results show that functionalization with Rudim maintains the electronic sp 2 hybridization of the graphitic segment of Vulcan. Physicochemical characterization strongly suggests the formation of Pt-Ru alloyed phases at Pt/C Ru-dim : XRD shows about 50% Ru alloyed, while XPS indicates a shift of 0.31 eV towards higher BE of Pt 0. Such Pt-Ru interactions enhance the performance of Pt/C Ru-dim for the MOR in acid media by reaching a current density of 45.0 mA cm-2 , twofold increase compared to Pt/C. Moreover, the onset potential of 0.25 V determined for Pt/C Rudim is 0.14 V more negative relative to Pt/C. In summary, Pt/C Ru-dim shows enhanced catalytic properties for Direct Methanol Fuel Cells (DMFCs) applications.
Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon
Electrochimica Acta, 2008
PtRu nanoparticles deposited on a carbon black substrate are catalysts commonly employed for the electrooxidation of methanol and carbon monoxide-containing hydrogen feeds [1,. However, improvement of effective electrocatalysts is an essential goal in the development of a practical DMFC. The use of carbon black as a support for noble metals is frequent in the electrodes of polymer membrane electrolyte fuel cells, but the impact of the chemical and physical properties of the carbon on electrocatalytic performance are not yet sufficiently understood. The presence of oxygen surface groups influences the surface behaviour of carbons to a considerable extent . As examples, the wettability and adsorptive behaviour of a carbon, as well as its catalytic and electrical properties, are influenced by the nature and extent of such surface groups. The varying role of oxygenated functionalities on the formation of the dispersed platinum has been established [5-8], but not with an additional metal such as ruthenium. In the present investigation we report how the performance in methanol electrooxidation of PtRu nanoparticles deposited on a carbon black substrate, previously functionalized with oxygen surface groups, is improved.
Methanol oxidation on MoO 3 promoted Pt/C electrocatalyst
2011
MoO 3 is incorporated into Vulcan carbon XC-72R by solidestate reaction under intermittent microwave heating (IMH) method. The Pt nanoparticles are dispersed by microwaveassisted polyol process. The physicochemical characterization reveals that MoO 3 and Pt nanoparticles are evenly deposited on Vulcan carbon XC-72R. The non-conducting MoO 3 is electrochemically reduced to nonstoichiometric and electroconductive hydrogen molybdenum bronze (H x MoO 3) in acidic solution. The peak current for methanol electrooxidation is about 128% higher on Pt-MoO 3 /C electrode than Pt-Ru/C electrode. Also, there is a significant increase in the electrode response toward stability test which can be attributed to hydrogen molybdenum bronze phase and its direct role in the conversion of CO to CO 2. Intermittent microwave heating method is effective for incorporating oxide materials in Vulcan XC-72R in a short span of time which is evidenced by the formation of hydrogen molybdenum bronze phase during the CV measurements.
Effect of third metal on the electrocatalytic activity of PtRu/Vulcan for methanol electro-oxidation
Journal of Solid State Electrochemistry, 2008
The effect of a third metal on the activity of PtRu/ Vulcan toward methanol oxidation reaction (MOR) is studied. An efficient method to prepare ternary catalysts was used, which allows the introduction of the third metal to PtRu/ Vulcan without altering its particle size or dispersion. Ni, Mo, Co, and Ir were chosen and added to PtRu/Vulcan, based on theoretical and experimental literature results, anticipating enhancement in the catalytic activity of PtRu/Vulcan. The composition of the third metal can be varied from trace to considerable amounts. Transmission electron microscopy and energy-dispersive X-ray analysis were used to determine the particle size, dispersion, and the composition of the ternary catalysts. Cylic voltammetry, chronoamperometry, and COstripping voltammetry were used to analyze and compare the activities of the catalysts at 25°C. It has been found that the addition of even trace amounts of third metal significantly affects the catalytic activity of PtRu toward MOR.
Several Pt-Co catalyst nanoparticles supported on sulfur-modified carbon nanotubes (CNTs) have been synthesized and used for methanol oxidation reaction (MOR) in acidic solutions. The catalysts were prepared by impregnation of the catalyst precursors on the CNTs and then alloying at 800°C under an atmosphere of H 2 /Ar. The results indicated that in spite of high annealing temperature, the catalyst nanoparticles were highly distributed on the support with an average particle size of $3 nm and narrow size distribution. Among the catalysts, Pt 3 Co/CNT showed highest MOR activity. Moreover, the high temperature annealing process resulted in the formation of faceted cubo-octahedral nanocrystals with high stability in acid solutions and electrochemical environments. The results demonstrated the effectiveness of sulfur-modified CNTs as a precursor for the synthesis of catalyst nanoparticles, without the need for tedious pretreatment procedures to modify CNTs or complex equipments to achieve high dispersion of nanoparticles on the CNT support.
Pt and PtRu nanoparticles deposited on single-wall carbon nanotubes for methanol electro-oxidation
Journal of Power Sources, 2007
Platinum (Pt) and platinum-ruthenium (PtRu) nanoparticles supported on Vulcan XC-72 carbon and single-wall carbon nanotubes (SWCNT) are prepared by a microwave-assisted polyol process. The catalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The PtRu nanoparticles, which are uniformly dispersed on carbon, have diameters of 2-6 nm. All the PtRu/C catalysts display the characteristic diffraction peaks of a face centred cubic Pt structure, excepting that the 2θ values are shifted to slightly higher values. The results from XPS analysis reveal that the catalysts contain mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV) and Ru(IV). The electrooxidation of methanol is studied by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. Both PtRu/C catalysts have high and more durable electrocatalytic activities for methanol oxidation than a comparative Pt/C catalyst. Preliminary data from a single direct methanol fuel cell using the SWCNT supported PtRu alloy as the anode catalyst delivers high power density.
Journal of Power Sources, 2007
In the anodes of direct methanol fuel cells (DMFCs), Pt poisoning by CO adsorption during methanol electro-oxidation has been a serious problem. Efforts to overcome or minimize this obstacle have largely involved investigations of PtRu bimetallic catalysts. In order to prepare fine PtRu alloyed hydrosols, we used non-ionic surfactants including L121, Pluronic P123, P65, Brij 35, and Tween 20 as stabilizers in this study. The sizes of the prepared metal particles change with the surfactant used. The finest metal hydrosol is obtained when Pluronic P123 and P65 are used. The resulting metal hydrosols with Pluronic P123, Brij 35 and Tween 20 are supported on Vulcan XC-72R. PtRu/XC-72R prepared with Pluronic P123 exhibits the best catalytic activity due to better dispersion of the alloyed metal. To improve further the activity of the PtRu catalyst, the commercial Vulcan XC-72R is replaced with carbon spherule (CS), a home-made carbon support. Electrochemical analyses such as cyclic voltammetry and galvanostatic-polarization tests are performed to evaluate the prepared catalyst. PtRu/CS has a superior performance to PtRu/XC-72R in methanol electro-oxidation when Pluronic P123 is employed as the stabilizer. The higher conductivity and larger inter-particle space of the CS appear to facilitate methanol electro-oxidation.