共查询到20条相似文献,搜索用时 0 毫秒
1.
Jae Ho Choi Soon Young Noh Sam Duck Han Soo Kyung Yoon Chang-Soo Lee Taek-Sung Hwang Young Woo Rhee 《Korean Journal of Chemical Engineering》2008,25(5):1026-1030
The oxidation of formic acid by the palladium catalysts supported on carbon with high surface area was investigated. Pd/C
catalysts were prepared by using the impregnation method. 30 wt% and 50 wt% Pd/C catalysts had a high BET surface area of
123.7 m2/g and 89.9 m2/g, respectively. The fuel cell performance was investigated by changing various parameters such as anode catalyst types,
oxidation gases and operating temperature. Pd/C anode catalysts had a significant effect on the direct formic acid fuel cell
(DFAFC) performance. DFAFC with Pd/C anode catalyst showed high open circuit potential (OCP) of about 0.84 V and high power
density at room temperature. The fuel cell with 50 wt% Pd/C anode catalyst using air as an oxidant showed the maximum power
density of 99 mW/cm2. On the other hand, a fuel cell with 50 wt% Pd/C anode catalyst using oxygen as an oxidant showed a maximum power density
of 163 mW/cm2 and the maximum current density of 590 mA/cm2 at 60 °C. 相似文献
2.
Sam Duck Han Jae Ho Choi Soon Young Noh Kunyik Park Soo Kyung Yoon Young Woo Rhee 《Korean Journal of Chemical Engineering》2009,26(4):1040-1046
Palladium particles supported on porous carbon of 20 and 50 nm pore diameters were prepared and applied to the direct formic
acid fuel cell (DFAFC). Four different anode catalysts with Pd loading of 30 and 50 wt% were synthesized by using impregnation
method and the cell performance was investigated with changing experimental variables such as anode catalyst loading, formic
acid concentration, operating temperature and oxidation gas. The BET surface areas of 20 nm, 30 wt% and 20 nm, 50 wt% Pd/porous
carbon anode catalysts were 135 and 90 m2/g, respectively. The electro-oxidation of formic acid was examined in terms of cell power density. Based on the same amount
of palladium loading with 1.2 or 2 mg/cm2, the porous carbon-supported palladium catalysts showed higher cell performance than unsupported palladium catalysts. The
20 nm, 50 wt% Pd/porous carbon anode catalyst generated the highest maximum power density of 75.8 mW/cm2 at 25 °C. Also, the Pd/porous carbon anode catalyst showed less deactivation at the high formic acid concentrations. When
the formic acid concentration was increased from 3 to 9 M, the maximum power density was decreased from 75.8 to 40.7 mW/cm2 at 25 °C. Due to the high activity of Pd/porous carbon catalyst, the cell operating temperature has less effect on DFAFC
performance. 相似文献
3.
Jeong Soo Kim Jae Keun Yu Hyo Song Lee Jin Yong Kim Young Chun Kim Jong Hee Han In Hwan Oh Young Woo Rhee 《Korean Journal of Chemical Engineering》2005,22(5):661-665
We investigated the effect of temperature, oxidant and catalyst loading on the performance of direct formic acid fuel cell
(DFAFC). When oxidant was changed from air to oxygen, the power density was increased to 17.3 mW/ cm2 at 25 ‡C. The power density of DFAFC operated with oxygen showed a maximum value of 40.04 mW/cm2 with the temperature rise from room temperature to 70 °C. The highest power density of DFAFC using air was observed for Pt-Ru
black catalyst with loading of 8 mgPt/cm2 at room temperature. At 70 ‡C; however, the performance of catalyst with the loading of 4 mgPt/cm2 was higher than that of 8 mgPt/cm2. The DFAFC, operated with oxygen and catalyst of 4 mgPt/cm2 loading, showed the best performance at all temperature range. The enhancement of cell performance with an increase of catalyst
loading is believed to come from an increase of catalyst active sites. However, operated at higher temperature or with oxygen,
the cell with higher catalyst loading showed lower performance than expected. It is speculated that the thick catalyst layer
inhibits the proton transport. 相似文献
4.
Xingwen Yu 《Electrochimica acta》2010,55(24):7354-7361
PtPb/C and PtSb/C bi-metallic catalysts were synthesized by chemical deposition of Pb or Sb on a commercial 40% Pt/C catalyst. The performances of catalysts with a range of compositions were compared in a multi-anode direct formic acid fuel cell in order to optimize compositions and evaluate the statistical significance of differences between catalysts. The catalytic activity for formic acid oxidation increased approximately linearly with adatom coverage for both PtPb/C and PtSb/C, to maxima at fractional coverages of ca. 0.7. At a cell voltage of 0.5 V, the currents at the optimum Pb or Sb coverages were ca. 8 times higher than at unmodified Pt/C. CO-stripping results indicate that the presence of Pb or Sb facilitates the oxidation of adsorbed CO. In addition, both metals appear to produce electronic effects that inhibit poison formation on the modified Pt surface. 相似文献
5.
Carbon supported PtBi bimetallic catalysts (PtBi/C) prepared by depositing Bi on a commercial Pt/C catalyst and by codeposition of Pt and Bi have been compared for formic acid oxidation in a multi-anode direct formic acid fuel cell. Both types of catalyst gave much higher cell performances than the Pt/C, with only low amounts of Bi (Pt to Bi mole ratios of 11:1 and 14:1, respectively) required for optimum performance. The high Pt to Bi ratio for the best codeposited catalyst indicates that the Bi was concentrated at the surface, and this is consistent with X-ray diffraction and X-ray photoelectron spectroscopy results. However, cyclic voltammetry revealed a strong electronic effect that is inconsistent with surface decoration. The effects of the Bi have been attributed to selective blocking of sites at which CO is formed. 相似文献
6.
We report the mass transport characteristics of formic acid and performance enhancement in a direct formic acid fuel cell in terms of the property of anode components. The effect of hydrophobicity of anode diffusion media as well as catalyst layer was investigated applying different cell temperature and fuel concentration. The operation over 80 °C and concentrated formic acid is of great advantage to the enhancement of catalytic activity and better water management. On the other hand, the conductivity of formic acid decreases by means of the formation of more complex chains of formic acid and the fuel cell resistance increases by membrane dehydration effect due to the hygroscopic property of formic acid, resulting in overall decrease of cell performance and long-term stability. Optimizing operating conditions, the use of 60% PtRu/C with only 1 mg/cm2 on plain carbon paper can be one of the good choice to achieve both sustainable power performance and higher utilization of anode catalysts keeping cell resistance. 相似文献
7.
A demonstration of direct formic acid fuel cells (DFAFCs) generating very high power density at ambient temperature is reported. In particular, the performance of the Pd black as an anode catalyst for DFAFCs with different formic acid feed concentrations at different operating temperatures has been evaluated. The Pd black based DFAFCs with dry air and zero backpressure can generate a maximum power density of 248 and 271 mW cm–2 at 22 °C and 30 °C respectively. The open cell potential is 0.90 V. These results show that DFAFCs are potentially excellent alternative power sources for small portable electronic devices. 相似文献
8.
Previous work has shown that palladium catalysts are quite active for formic acid electrooxidation, but the catalysts need to be periodically regenerated to remove a CO impurity from the surface. The objective of this paper is to determine whether antimony additions could suppress the CO formation under fuel cell conditions. We find that antimony doubles the rate of reaction in an electrochemical cell, but the increase is less in real fuel cell conditions. The current that is produced at 0.6 V is approximately 14% greater for the fuel cell containing antimony additions than the palladium anode catalyst. In a constant-current test, we find that the fuel cell assembled with palladium-antimony anode catalyst produces 18% more voltage than the palladium anode catalyst after 9 h of operation. These results show that the antimony additions that significantly improve oxidation in the electrochemical cell have a much lesser impact in the formic acid fuel cell - they do not suppress CO formation in the fuel cell as anticipated. 相似文献
9.
10.
直接甲酸燃料电池研究进展 总被引:1,自引:0,他引:1
直接甲酸燃料电池是近年来出现的一类新型燃料电池.本文从直接甲酸燃料电池的原理、阳极和阴极催化剂、小型直接甲酸燃料电池电池堆的研究开发等几个方面,对直接甲酸燃料电池的国内外研究现状进行了较为系统的介绍,并指出了直接甲酸燃料电池目前的发展遇到的困难及挑战. 相似文献
11.
Direct formic acid fuel cells (DFAFC) currently employ either Pt-based or Pd-based anode catalysts for oxidation of formic acid. However, improvements are needed in either the activity of Pt-based catalysts or the stability of Pd-based catalysts. In this study, a number of carbon-supported Pt-based and Pd-based catalysts, were prepared by co-depositing PdM (M = Bi, Mo, or V) on Vulcan® XC-72 carbon black, or depositing another metal (Pb or Sn) on a Pt/C catalyst. These catalysts were systematically evaluated and compared with commercial Pd/C, PtRu/C, and Pt/C catalysts in a multi-anode DFAFC. The PtPb/C and PtSn/C catalysts were found to show significantly higher activities than the commercial Pt/C catalyst, while the PdBi/C provided higher stability than the commercial Pd/C catalyst. 相似文献
12.
We reported that various compositions of AuPt nanoparticles synthesized as an anode material for formic acid fuel cell were investigated. Its surface characteristics were systematically analyzed using XRD and TEM and anodic electrocatalytic activity was studied using a linear sweep voltammetry technique in 0.5 M H2SO4 + 1 M HCOOH. In addition, the voltage-current curve and power density of home-made AuPt-based membrane-electrode-assembly (MEA) and commercial Pt0.5Ru0.5-based MEA was measured at 60 °C in 9 M formic acid. The maximum power density of Au0.6Pt0.4-based MEA was 30% higher than that of PtRu-based MEA which were 200 mW cm−2 and 155 mW cm−2, respectively. 相似文献
13.
Due to the inherent inertness of carbon nanotubes (CNTs), one of the most significant challenges in the preparation of CNT-supported catalysts is achieving a uniform deposition of nanoparticles on the surface of the nanotubes. In this paper, we report on the preparation and characterization of Pd nanoparticles supported on untreated multi-walled carbon nanotubes (MWCNTs), synthesized in the presence of glutamate. The results of Raman spectroscopy revealed that this synthetic procedure does not have a detrimental effect on the surface structure of MWCNTs. Transmission electron microscopy (TEM) measurements indicated that the dispersion of Pd nanoparticles on untreated-MWCNTs in the presence of glutamate were uniform, and a narrow particle size was observed. X-ray diffraction (XRD) patterns indicated that the Pd/MWCNT catalyst possessed a face-centered cubic crystal structure. Cyclic voltammetry and chronoamperometry tests demonstrated that the obtained Pd/MWCNT catalyst displayed superior electrocatalytic activity and stability in formic acid oxidation, as compared to both a Pd/MWCNT catalyst synthesized without glutamate and a Pd catalyst on acid-oxidized MWCNTs, under otherwise identical experimental conditions. These results indicate that the catalyst developed in this study is a superior candidate for direct formic acid fuel cells (DFAFCs). 相似文献
14.
Chaojie Song Mohammad Khanfar Peter G. Pickup 《Journal of Applied Electrochemistry》2006,36(3):339-345
Pt black and PtRu black fuel cell anodes have been modified with Mo oxide and evaluated in direct methanol, formaldehyde and
formic acid fuel cells. Mo oxide deposition by reductive electrodeposition from sodium molybdate or by spraying of the fuel
cell anode with aqueous sodium molybdate resulted in similar performance gains in formaldehyde cells. At current densities
below ca. 20 mA cm−2, cell voltages were 350–450 mV higher when the Pt catalyst was modified with Mo oxide, but these performance gains decreased
sharply at higher current densities. For PtRu, voltage gains of up to 125 mV were observed. Modification of Pt and PtRu back
catalysts with Mo oxide also significantly improved their activities in direct formic acid cells, but performances in direct
methanol fuel cells were decreased. 相似文献
15.
Jae Kwang Lee 《Electrochimica acta》2008,53(21):6089-6092
We first reported on electrocatalytic activity and stability of antimony modified platinum (PtSbupd) as anode catalyst in direct formic acid fuel cells. Sb modified Pt (PtSbupd) was prepared by underpotential deposition technique applying constant potential of 0.2 V (vs. Ag/AgCl, 3M KCl) and its modified surface was characterized by XRD and XPS. The electrocatalytic oxidation activity by cyclic voltammograms and the single cell power performance of Sb modified Pt were measured and their results were compared with the data of unmodified Pt electrode. PtSbupd induced lower onset potential of formic acid oxidation and twice higher power density of 250 mW cm−2 was observed. 相似文献
16.
Wet-chemical assembling process has been developed for the formation of the anode electrocatalyst layers of a micro tubular direct formic acid fuel cell. By using this method, a porous layer of Pd nano-catalyst was bonded onto the inner surface of a tubular polymer electrolyte membrane by chemical reduction of Pd complex impregnated in the membrane. The performance characteristics as a function of parameters such as catalyst loading amount of Pd or the cell temperature were evaluated by using a half-cell testing method. The micro tubular DFAFC with a 2.5 mg-Pd cm−2 anode and 6 mg-Pt cm−2 cathode fabricated by wholly wet-chemical assembling process exhibited a peak power density over 4 mW cm−2 under passive and air breathing conditions at ambient temperature and pressure. 相似文献
17.
Jinglin Zhou Xiongfu Zhang Jian Zhang Haiou Liu Li Zhou KingLun Yeung 《Catalysis communications》2009,10(14):1804-1807
A thin layer of silicalite-1 zeolite membrane was grown on the surface of Ni/SiO2 and Ni/Al2O3 catalyst beads after seeding and secondary regrowth to create core–shell catalysts that are resistant to alkali poisoning from direct internal reforming-molten carbonate fuel cell (DIR-MCFC). The zeolite shell thickness was optimized to prevent poisoning and minimize diffusion resistance. An out-of-cell test was designed to simulate the fuel cell operating conditions, which showed that the new core–shell catalysts maintained a high activity similar to the original fresh catalyst in spite of the exposure to alkali vapor at high temperature. The conventional Ni/SiO2 and Ni/Al2O3 catalysts suffered higher than 80% decrease in activity for steam reforming of methane reaction (SRM). 相似文献
18.
The Pt3Sn/C catalyst with high electrochemical activity was synthesized under optimizing preparation conditions. The surface of carbon support pretreated by strong acid contains many O-H and CO groups, which will increase the active sites of PtSn/C catalysts. The catalyst structure was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and temperature programmed reduction (TPR). The co-reduction of Pt4+ and Sn2+ ions causes Sn to enter Pt crystal lattice to form PtSn alloy whose surface, however, contains tin oxides with Sn4+ and Sn2+ valences, which can promote the ethanol oxidation. The crystallinity of PtSn decreases with the reduction of the atomic ratio of Pt:Sn. By prolonging the reaction time of formic acid, the forward anodic peak current of ethanol oxidation reaches 16.2 mA on the Pt3Sn/C catalyst with 0.025 mg Pt loading. 相似文献
19.
Palladium catalyst poisoned in the anode of direct formic acid fuel cell (DFAFC) during constant current discharging can be fully regenerated by a non-electrochemical method, i.e. just switching pure water to DFAFC for 1 h. Electrochemical impedance spectrum of DFAFC during the discharging and regeneration were recorded and analyzed. No much difference could be found for the high-frequency resistance of DFAFC after discharging while the charge transfer resistance in the mediate-frequency region increased significantly. The voltage variation during the regeneration showed that one platform of 0.35 V was formed by the intermediate species of formic acid oxidation, which is proven to be critical for cell performance regeneration. The results indicated that the absorption of poisoning species on Pd was the main reason for the decaying of cell performance. 相似文献
20.
This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst
loading in anodes for methanol electrooxidation. The direct methanol fuel cell’s (DMFC) anodic catalysts, Pt-Ru/C, were prepared
by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances. The reducing agent
was added in hot solution with the protection of inert gases or just air, and in cold solution with inert gases. The catalysts
were treated at different temperatures. Their performance was tested by cyclic voltammetry and potentiostatic polarization
by utilizing their inherent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/LH2SO4 solution. The structures and micro-surface images of the catalysts were determined and observed by X-ray diffraction and
transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance
for methanol electrooxidation than that prepared in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy
in carbon. Its size is small, only about 4.5 nm. The catalytic performance is affected by the order of the reducing agent
added. The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better
than that prepared by adding it in the solution at 0°C and then heating it up to the reducing temperature. The structure of
the catalyst was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase
in particle size with the ascension of heat treatment temperature. In addition, the stability of the catalyst was improved
after heat treatment.
Translated from Journal of Harbin Institute of Technology, 2006, 38 (4): 541-545 [译自: 哈尔滨工业大学学报] 相似文献