共查询到16条相似文献,搜索用时 125 毫秒
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炭载TiO_2与PEG混合,超声振荡1 h,80℃搅拌2 h。滴加氯铂酸,调节p H值,分别用Na BH4,甲醛及甲酸还原,制得Pt-TiO_2/C催化剂a,b及c。用循环伏安法研究甲醇及CO分别在25℃和60℃的0.5 mol/L H2SO4溶液中在Pt-TiO_2/C上的氧化情况。结果表明,甲醇在60℃的酸性溶液中氧化时3种催化剂的氧化峰电位增大,峰电流密度升高,起始峰电位负移,说明升高温度有利于甲醇氧化,并且无论在25℃还是在60℃,催化剂c的电氧化能力最好,起始氧化电位最低,峰电流和峰电位最大。60℃时CO的峰电流密度和25℃时相比无太大变化,但起始氧化电位和峰电位明显负移,说明升高温度对CO的电氧化很有利,催化剂c的抗CO能力比a,b强,活性最高。 相似文献
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利用循环伏安法电聚合导电高分子聚苯胺,并制备了Pt/PAn/GC电极和Pt/GC电极,优化了苯胺在玻碳电极上的聚合条件,用在H2SO4中的循环伏安曲线对其进行了表征,Pt/PAn/GC电极的制备提高了Pt的分散度,增加了催化剂Pt的利用率。实验结果表明Pt/PAn/GC电极对甲酸电氧化的催化活性明显高于Pt/GC电极和Pt电极,正向扫描和反向扫描时对应的氧化峰电位分别是0.68V、0.45V。峰电流为54.23mA/cm^2和84.23mA/cm^2,为Pt/GC电极的修饰电极1.7倍和1.9倍,为Pt片电极的3.8倍和4.9倍,有效地提高了铂微粒的催化活性,并得到聚合苯胺的最佳条件为扫描速度50mV/s、扫描上限1.2V。 相似文献
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分别以硼氢化钠和乙二醇为还原剂,经络合还原法制备了炭载钯(Pd/C)催化剂。透射电镜(TEM)和X射线粉末衍射谱(XRD)结果表明,以乙二醇为还原剂制备的Pd/C催化剂中Pd粒子具有较小的粒径、均匀的粒径分布和较大的相对结晶度,Pd粒子的平均粒径和相对结晶度分别为4.2±2 nm和1.88。电化学测试结果显示,以乙二醇为还原剂制备的Pd/C催化剂具有较大的电化学活性面积,对甲酸氧化表现出较高的电催化活性和稳定性。 相似文献
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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
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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
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Different Pt and Pd catalysts supported on an activated carbon were prepared by using different metal precursors. Prepared catalysts were pretreated at 400 °C under different atmospheres to decompose the precursor compound and reduce the metal. After pretreatments, the supported catalysts were characterized by H2 chemisorption, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy to know their metal dispersion, particle size, distribution and oxidation state. Afterwards, the catalysts were tested in methanol partial oxidation with two different O2/CH3OH molar ratios. Results obtained in this reaction were compared with those obtained for methanol decomposition in inert atmosphere. For Pt catalysts, there was an increase in methanol conversion and hydrogen production and a decrease in carbon monoxide production under oxidizing conditions. Both methanol conversion and partial oxidation reactions appear to be sensitive to Pt particle structure in the particle size range studied. Results obtained under oxidizing conditions differed between Pd and Pt catalysts. Finally, catalytic activity in methanol partial oxidation was more affected by Pt than Pd particle size in the size range studied. 相似文献
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《Electrochimica acta》1995,40(12):1889-1897
The effect of particle size of ultrafine palladium particles on the electrochemical oxidation of formic acid in a perchloric acid solution has been investigated by cyclic voltammetry (CV) and differential electrochemical mass spectroscopy (DEMS). Except in the hydrogen sorption-desorption region, only carbon dioxide was observed by the DEMS as an oxidation product, and the profile of the imass-E curve was in fair agreement with that of i-E curves. With a decrease in the palladium particle size, the specific activity of the palladium particles for the oxidation of formic acid gradually increased until ca. 3 nm in the mean diameter, and then it steeply decreased. 相似文献
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Takashi Matsui Masaru Harada Kyoko K. Bando Makoto Toba Yuji Yoshimura 《Applied Catalysis A: General》2005,290(1-2):73-80
The sulfur tolerance of monometallic Pd, Pt and bimetallic Pd–Pt catalysts supported on slightly acidic ultra-stable Y (USY) zeolite (SiO2/Al2O3 = 390) and on non-acidic silica, having mesopores with a pore diameter of 3 or 10 nm, were investigated using the CO adsorption method and the extended X-ray adsorption fine structure (EXAFS) method. Well-dispersed noble metal particles supported on USY zeolite and silica with an average pore diameter of 3 nm showed high surface sulfur tolerance and high catalytic hydrogenation activity, although bulk phase sulfidation simultaneously occurred. The synergistic effects of sulfur tolerance were significant in the bimetallic Pd–Pt particles supported on USY zeolite and silica with an average pore diameter of 3 nm. On the other hand, on silica with an average pore diameter of 10 nm, the surface sulfur tolerance of low dispersed noble metals was the lowest, although its bulk phase sulfur tolerance was the highest. The Pd K-edge and Pt LIII-edge EXAFS spectra indicated a strong interaction between the well-dispersed noble metal particles and the supports of the USY zeolite and silica with an average pore diameter of 3 nm. This distorted structure may increase the sulfur tolerance of noble metals, though some surface and bulk phase sulfidation simultaneously occurred. 相似文献