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1.
Methanol electrooxidation was investigated on Pt–Ru electrocatalysts supported on glassy carbon. The catalysts were prepared
by electrodeposition from solutions containing chloroplatinic acid and ruthenium chloride. Bulk composition analysis of the
Pt–Ru catalyst was performed using an X-ray detector for energy dispersive spectroscopy analysis (EDX). Three different compositions
were analyzed in the range 0–20 at.% Ru content. Tafel plots for the oxidation of methanol in solutions containing 0.1–2 M
CH3OH, and in the temperature range 23–50 °C showed a reasonably well-defined linear region. The slope of the Tafel plots was
found to depend on the ruthenium composition. The lower slope was determined for the Pt catalyst, varying between 100 and
120 mV dec−1. The values calculated for the alloys were higher, ranging from 120 to 140 mV dec−1. The reaction order for methanol varies from 0.5 to 0.8, increasing with the ruthenium content. The activation energy calculated
from Arrhenius plots was found to change with the catalyst composition, showing a lower value around 30 kJ mol−1 for the alloys, and a higher value, of 58.8 kJ mol−1, for platinum. The effect of ruthenium content is explained by the bifunctional reaction mechanism. 相似文献
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R.S. Amin R.M. Abdel Hameed K.M. El-Khatib M. Elsayed Youssef A.A. Elzatahry 《Electrochimica acta》2012
Pt catalyst was supported on Vulcan XC-72R containing 5 wt.% NiO using NaBH4 as a reducing agent. The prepared catalyst was heat-treated at 400 °C. XRD, TEM and EDX analyses were applied to characterize Pt–NiO/C electrocatalyst. The introduction of NiO reduces the particle size of Pt crystallites. The electrocatalytic activity of Pt–NiO/C electrocatalysts was examined towards methanol oxidation reaction in 0.5 M H2SO4 solution using cyclic voltammetry and chronoamperometry techniques. A three fold increment in the oxidation current density was gained at Pt–NiO/C electrocatalyst compared to Pt/C one. The corresponding chronoamperograms showed high steady state current density values suggesting better stability of Pt–NiO/C electrocatalyst towards the carbonaceous poisoning species. The enhanced electrocatalytic performance and the long-term cycle durability of Pt–NiO/C electrocatalyst are attributed to the strong interaction between Pt and NiO and the formation of small Pt crystals. 相似文献
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A.S. Aricò A.K. Shukla K.M. El-Khatib P. Cretì V. Antonucci 《Journal of Applied Electrochemistry》1999,29(6):673-678
The structure, chemistry and morphology of commercially available carbon-supported and unsupported Pt–Ru catalysts are investigated by X-ray diffraction, energy-dispersive analysis by X-rays and electron microscopy. The catalytic activities of these materials towards electrooxidation of methanol in solid-polymer-electrolyte direct methanol fuel cells have been investigated at 90C and 130C with varying amounts of Nafion ionomer in the catalytic layer. The unsupported Pt–Ru catalyst exhibits higher performance with lower activation-control and mass-polarization losses in relation to the carbon-supported catalyst.On leave from the 相似文献
5.
Carbon-supported Pt–Ru–WOx/C catalysts for application in PEMFC anodes were synthesized by a modified Bönnemann method. Their electrocatalytic activity for the oxidation of H2/CO mixtures and CH3OH was measured by E/i-curves in PEM single cell arrangements under working conditions. Information about composition, microstructure and nanomorphology was obtained by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence analysis (XFA) and transmission electron microscopy (TEM). X-ray diffraction data at room temperature show only one single Pt f.c.c. phase; no evidence of Ru, W and their oxides, respectively, is found. Hence, the presence of W and Ru as amorphous oxide species seems likely. Surface-sensitive XPS measurements detect Pt0, platinum oxide and hydroxide species, metallic Ru, ruthenium oxide, hydrous ruthenium oxide and WO3. For the crystalline platinum phase particle sizes of less than 2 nm were determined by TEM images and XRD patterns via solving the Scherrer equation. Temperature-dependent XRD measurements were performed to show the influence of ageing on the catalyst structure. 相似文献
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Zheng Zhao Lu Zhang Qiaohua Tan Feifei Yang Jimmy Faria Daniel Resasco 《American Institute of Chemical Engineers》2019,65(1):151-160
Aqueous phase reforming (APR) of ethanol has been studied over a series of Ru and Pt catalysts supported on carbon and titania, with different metal loadings and particle sizes. This study proposed that, on both metals, ethanol is first dehydrogenated to acetaldehyde, which subsequently undergoes C C cleavage followed by different paths, depending on the catalyst used. For instance, although monometallic Pt has high selectivity toward H2 via dehydrogenation, it has a low efficiency for C C cleavage, lowering the overall H2 yield. Large Ru particles produce CH4 through methanation, which is undesirable because it consumes H2. Small Ru particles have lower activity but higher selectivity toward H2 rather than CH4. On these small particles, CO blocks low-coordination sites, inhibiting methanation. The combination of the two metals in bimetallic Ru–Pt catalysts results in improved performance, benefiting from the desirable properties of each Ru and Pt, without the negative effects of either. © 2018 American Institute of Chemical Engineers AIChE J, 65: 151–160, 2019 相似文献
8.
《Ceramics International》2017,43(14):10698-10707
To prevent undesirable reactions between the cathode and electrolyte materials in cathode-supported solid oxide fuel cells (SOFCs), the co-sintering temperature of these two layers must be lowered. In the present work, we employed different strategies to lower the co-sintering temperature of cathode–electrolyte bilayers for micro-tubular SOFCs by increasing the cathode sintering shrinkage and adding sintering aids to the electrolyte. Strontium-doped lanthanum manganite (LSM) and yttria-stabilized zirconia (YSZ) were used as the cathode and electrolyte materials, respectively. To facilitate densification of the electrolyte layer by controlling the shrinkage of the cathode support, the particle size of the LSM powder was reduced by high-energy ball milling and different amounts of micro-crystalline cellulose pore former were used. Sintering aids, namely NiO and Fe2O3, were also added to the YSZ electrolyte to further improve its low-temperature sintering. Our results indicate that with the improvement in the cathode support shrinkage and use of the small amounts of sintering aids, the cathode–electrolyte co-sintering temperature can be reduced to 1250–1300 °C. It was also observed that the presence of the sintering aids helps to reduce the reactivity between the LSM cathode and YSZ electrolyte. 相似文献
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《Catalysis communications》2008,9(2):256-261
The catalytic performance of Cu–ZnO/Pd-β catalyst for syngas to LPG (Liquefied Petroleum Gas) has been investigated in this paper. The kind of zeolite, SiO2/Al2O3 ratio in Pd-β, Pd-β particle size, Pd content in Pd-β, and reaction conditions, have been optimized. The results showed that the suitable reaction conditions for syngas to LPG over Cu–ZnO/Pd-β are: 325–350 °C, 2.1–3.6 MPa, 4.5–9 g h/mol gas velocity (W/F), and 37–75 ratio of SiO2/Al2O3. At the optimal conditions, Cu–ZnO/Pd-β could exhibit an excellent catalytic performance for syngas to LPG: 72.2% CO conversion, 45.3% hydrocarbon yield and 78.0% LPG selectivity in hydrocarbons could be achieved. 相似文献
11.
Dae-Soo Yang Kwang-Sik Sim Hai-Doo Kwen Seong-Ho Choi 《Journal of Industrial and Engineering Chemistry》2012,18(1):538-545
Pt–M@FP-MWNT catalysts (M = Ru, Ni, Co, Sn, and Au) were prepared by one-step γ-ray irradiation. Two different types of functional polymers (FP), such as poly(vinylphenyl boronic acid) (PVPBAc) and poly(vinylpyrorridone) (PVP), were used as anchoring agents, when Pt–M nanoparticles were deposited on the multi-walled carbon nanotube (MWNT) using γ-ray irradiation in aqueous solution at room temperature. The obtained Pt–M@FP-MWNT catalysts were then characterized by XRD, TEM, and elemental analysis. The catalytic efficiency of the Pt–M@FP-MWNT catalysts was examined for CO stripping and MeOH oxidation for use in a direct methanol fuel cell (DMFC). The catalytic efficiency of the Pt–M@FP-MWNT catalyst for MeOH oxidation follows this order: Pt–Sn@FP-MWNT > Pt–Co@FP-MWNT > Pt–Ru@FP-MWNT > Pt–Au@FP-MWNT > Pt–Ni@FP-MWNT catalysts. The CO adsorption capacity of the Pt–M@FP-MWNT catalyst for CO stripping is as follows: Pt–Ru@FP-MWNT > Pt–Sn@FP-MWNT > Pt–Au@FP-MWNT > Pt–Co@FP-MWNT > Pt–Ni@FP-MWNT catalyst. 相似文献
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L. Giorgi A. Pozio C. Bracchini R. Giorgi S. Turtù 《Journal of Applied Electrochemistry》2001,31(3):325-334
The oxidation kinetics of H2 and H2 + 100 ppm CO were investigated on Pt, Ru and Pt–Ru electrocatalysts supported on a high-surface area carbon powder. The atomic ratios of Pt to Ru were 3, 1 and 0.33. XRD, TEM, EDS and XPS were used to characterize the electrocatalysts. When alloyed with ruthenium, a decrease in mean particle size and a modification of the platinum electronic structure were identified. Impedance measurements in H2SO4, at open circuit potential, indicated different mechanisms for hydrogen oxidation on Pt/C (Tafel–Volmer path) and Pt–Ru/C (Heyrowsky–Volmer path). These mechanisms also occur in the presence of CO. Best performances, both in H2 and H2 + CO, were achieved by the catalyst with the ratio Pt/Ru = 1. This is due to a compromise between the number of free sites and the presence of adsorbed water on the catalyst. For CO tolerance, an intrinsic mechanism not involving CO electroxidation was proposed. This mechanism derives from changes in the electronic structure of platinum when alloyed with ruthenium. 相似文献
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A. S. Aricò E. Modica I. Ferrara V. Antonucci 《Journal of Applied Electrochemistry》1998,28(9):881-887
An electrode-kinetic study of the oxidation of CO and CO/H2 mixtures on a Pt–Ru/C catalyst was carried out in phosphotungstic acid (PWA) electrolyte. The influence of temperature, CO partial pressure and proton concentration on the electrochemical oxidation rate was investigated. An apparent activation energy of about 50kJmol–1 was found for CO oxidation at 0.6V vs NHE. Fractional reaction orders close to 0.5 and –0.4 with respect to carbon monoxide and proton concentration, respectively, were observed. Tafel slopes were close to 136mVdec–1 at 70°C for both CO and CO/H2 oxidation. The PWA electrolyte appeared to promote the methanol electrooxidation by increasing the rate of water discharge at the electrode. 相似文献
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F. Smeacetto M. Salvo F.D. D’Hérin Bytner P. Leone M. Ferraris 《Journal of the European Ceramic Society》2010,30(4):933-940
This work describes the design of three new glass and glass ceramic compositions to join the ceramic electrolyte (YSZ wafer) to the metallic interconnect (Crofer22APU) in planar SOFC stacks. The designed sealants are low-sodium, barium free and boron-oxide free silica-based glasses.The sealing process was optimized for the most promising composition and joined Crofer22APU/glass–ceramic sealant/YSZ samples were morphologically characterized and tested for 300 h in humidified hydrogen atmosphere at the fuel cell operating temperature of 800 °C. The study showed that the use of the glass–ceramic was successful in joining the YSZ ceramic electrolyte to the Crofer22APU metallic interconnect and in preventing severe corrosion effects at the Crofer22APU/glass–ceramic interface after static treatments in humidified hydrogen at 800 °C for 300 h. 相似文献
16.
Dongxia Liu Yaritza M. López-De Jesús John R. Monnier Christopher T. Williams 《Journal of Catalysis》2010,269(2):376-387
A series of silica-supported Pt, Ru, and Pt–Ru catalysts has been synthesized using dendrimer–metal nanocomposite (DMN) precursors prepared by both co- and sequential complexation with metal salts. The catalysts have been characterized by several techniques, including electron microscopy, temperature-programmed titration of adsorbed oxygen, and X-ray diffraction. Liquid-phase selective hydrogenation of 3,4-epoxy-1-butene (EpB) was used as a probe reaction to evaluate their catalytic performance. The bimetallic catalyst prepared by the co-complexation method exhibits a superior catalytic activity compared to the sequential one, and is much more active than a conventional catalyst prepared by incipient wetness. The activity enhancement is attributed to a bifunctional performance of the PtRu alloy sites created, based on a strong correlation between turnover frequencies, and both the alloy compositions and metal surface site distributions. In addition, the co-complexation catalyst is selective toward crotonaldehyde, suggesting that this reaction pathway is favored on the PtRu sites. 相似文献
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Jing Xu Like Ouyang Guo-Jin Da Qian-Qian Song Xue-Jing Yang Yi-Fan Han 《Journal of Catalysis》2012,285(1):74-82
H2O2 synthesis directly from H2 and O2 over supported Pd–Pt alloy catalysts was carried out using a semibatch reactor under ambient conditions. As compared to pure Pd, the performance of Pd–Pt catalysts was enhanced significantly. The promotional role of Pt was studied systematically by using in situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption (DRIFTS), quantitative powder X-ray diffraction (XRD), X-rays photoelectron spectroscopy (XPS), and temperature-programmed desorption of H2/O2 (H2/O2-TPD). The spectra of DRIFT, XPS, and XRD demonstrate the formation of Pd–Pt alloy particles, which surfaces are enriched by Pt accompanying with possible electron transfer from Pd to Pt. The addition of Pt into Pd phase was proposed to impact on reactants adsorption, stabilization of intermediates such as OOH and OH radicals, and the formation and decomposition of H2O2. 相似文献
18.
Guillermo Díaz-Sainz Manuel Alvarez-Guerra José Solla-Gullón Leticia García-Cruz Vicente Montiel Angel Irabien 《American Institute of Chemical Engineers》2020,66(9):e16299
The use of bismuth-based catalysts is promising for formate production by the electroreduction of CO2 captured from waste streams. However, compared to the extensive research on catalysts, only a few studies have focused on electrochemical reactor performance. Hence, this work studied a continuous-mode gas–liquid–solid reaction system for investigating CO2 electroreduction to formate using Bi-catalyst-coated membrane electrodes as cathodes. The experimental setup was designed to analyze products obtained in both liquid and gas phases. The influence of relevant variables (e.g., temperature and input water flow) was analyzed, with the thickness of the liquid film formed over the cathode surface being a key parameter affecting system performance. Promising results, including a high formate concentration of 34 g/L with faradaic efficiency for formate of 72%, were achieved. 相似文献
19.
Je-Young Woo Kwang-Mun Lee Bong-Chul Jee Cheol-Hwi Ryu Cheol-Hun Yoon Jang-Hoon Chung Yong-Ryul Kim Sang-Bong Moon An-Soo Kang 《Journal of Industrial and Engineering Chemistry》2010,16(5):688-697
Membrane electrode assemblies (MEAs) of covalently cross-linked sulfonated poly(ether ether ketone) (CL-SPEEK)/heteropolyacids (HPAs) composite polymer with platinum-based alloys such as Pt–Ru–Co and Pt–Ru–Ni were prepared and their electrochemical properties for water electrolysis were investigated. The HPAs, which were used in the composite membranes, were tungstophosphoric acid (TPA) (the part of TPA data was permitted by the previous authors), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA). The MEAs with Pt–Co, Pt–Ru–Co, and Pt–Ru–Ni in the anode catalyst layer were prepared by means of a non-equilibrium impregnation–reduction (I–R) method. The electrocatalytic properties of composite membranes, such as the cell voltage and coulombic charge in CV, were in the following order: CL-SPEEK/MoPA40 > CL-SPEEK/TPA30 > CL-SPEEK/TSiA40 (wt%). For the optimum cell applications of water electrolysis, the cell voltage of Pt/PEM/Pt–Ru–Co (Electrodeposited (Dep)-MoPA) MEA with a CL-SPEEK/MoPA40 membrane was 1.70 V at 80 °C and 1 A cm?2, and this voltage carried a value lower than that of 1.81 V of Nafion 117. In addition, the observed activity of Pt–Ru–Co (75:12:13 by EDX) is a little higher than that of Pt–Ru–Ni (79:10:11 by EDX). The mean coulombic charge and activity enhancement of Pt–Ru–Co catalysts, with and without electrodeposition, showed the same CV profiles of the Pt–Ru–Co catalysts and were in the following order: Nafion 117 < CL-SPEEK/TSiA40 < CL-SPEEK/TPA30 < CL-SPEEK/MoPA40. The current density peak of electrodeposited electrodes was a little better than those of inactivated electrodes on the same membranes. The current peak by Pt–Ru–Co with CL-SPEEK/MoPA40 (Dep-MoPA) is more than about three times as high as those of Pt electrodes on the same membranes. 相似文献
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The electrooxidation of methanol, ethanol, and 2-propanol was investigated with interdigitated array electrodes (IDAEs). The IDAE oxidizes alcohol at the generator and reduces the reaction intermediates produced by the oxidation process at the collector. Thus, the reaction intermediates can be estimated with the IDAE. The IDAE in the present work was made of sputter deposited Pt and Pt–Ru. The use of Ru free and added electrodes provides information on the effect of Ru addition on the alcohol oxidation. Cyclic voltammetric analyses revealed that Ru addition enhances the oxidation currents and reduces the Eonset of the alcohols. The detectable reaction intermediate at the methanol and ethanol oxidation was proton, while the intermediate species was acetone in 2-propnaol oxidation. 相似文献