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21.
We report the electro-oxidation of formaldehyde on polyaniline films modified with Pt nanoparticles (PANI-Pt films) in an aqueous sulfuric acid solution. The electrodeposition of Pt particles on the PANI matrix was found to promote a mass loss of the film, with a similar effect occurring after cycling the PANI films in the acidic medium containing formaldehyde. However, despite the electrochemical instability of PANI-Pt films, on films containing larger amounts of incorporated Pt particles, the oxidation of formaldehyde produces adsorbed CO species (COads) at a lower positive potential than on bulk Pt. Our findings also indicate that electro-oxidation of COads on the PANI-Pt film surface depends not only on the thickness of PANI film but also on the amount of Pt particles incorporated into the PANI matrix. 相似文献
22.
Lead and indium were recovered by electrolysis and nonequilibrium solvent extraction process from lead bullion.The effects of current density,electrolytic period and circle amnant of electrolyte on the electrochemical dissolution of lead and indium were investigated.The effects of extraction phase ratio and mixing time on solvent extraction of indium and striping phase ratio and stripping stage on the loaded organic phase stripping were also investigated.The experimental results indicate that under optimum conditions,the purity of lead deposited on cathode is 98.5% and the deposit rate of lead is 99.9%,the dissolution rate of indium is 94.28%,the extraction rate of indium is 98.69%,the stripping rate of indium is almost 100%,and the impurity elements,such as Zn,Fe and Sn can be removed. 相似文献
23.
研究了在高温,高压(T=180℃,p=1.0~1.2×10^6Pa)的加磷酸盐情况下,苛性碱分解高钙黑钨精矿的工艺,试验表明,高钙钨精矿的分解率(η)可达98%以上,钨酸钠溶液中P/W比值也能满足工艺要求,与常温,常压工艺相比苛性碱的用量降低,分解时间缩短。 相似文献
24.
25.
用差示扫描量热法(DSC)研究了含氢20-240μg/g的N18、Zry-4和M5三种锆合金加热时氢化物完全溶解时的固溶度(TSSD)和冷却时氢化物开始析出时的固溶度(TSSP)并使用TSSD或TSSP数据拟合出最优方程.结果表明,这些合金的TSSD或TSSP差别都很小,TSSD与TSSP之间都存在显著的滞后,是氢化物与基体间的体积错配应变所导致.根据冷却时DSC放热峰的宽度,计算出氢化物从过饱和固溶体中析出的平均速率,并拟合出最优方程.氢化物析出的活化能与氢在锆合金中的扩散激活能近似,表明氢化物的析出受到氢扩散的控制. 相似文献
26.
Raquel P. RochaAdrián M.T. Silva Goran Dra?i?Manuel F.R. Pereira José L. Figueiredo 《Materials Letters》2012,66(1):64-67
Multi-walled carbon nanotubes (MWCNTs) were functionalized by HNO3 hydrothermal oxidation at 200 °C. The degree of surface functionalization was described by an exponential function in terms of HNO3 concentration. Very small Pt particles, with mean particle size of 1.7 ± 0.3 nm, could be supported on the surface of pristine MWCNTs and also on MWCNTs treated with HNO3 concentrations up to 0.20 mol L− 1, while a broader range of particle sizes, and larger Pt particles (3.4 ± 1.3 nm) were obtained on the MWCNTs treated with a higher HNO3 concentration (0.30 mol L− 1). Therefore, the amounts of surface groups and Pt particle sizes can be selected by tuning the HNO3 concentration used in the hydrothermal treatment. 相似文献
27.
测量了表面电阻值不同的两个电极试样的厚度及直流极化特性曲线,并由此分析了以表面电阻值作为电极评价指标的模糊性,提出了以电极极化程度来评价电极性能的概念。 相似文献
28.
Platinum catalyst for CO oxidation has been studied for decades,due to its high activity and good stability.In this work,we prepared three different lantha num oxide or hydroxide supports(LaOx(OH)y),and deposited platinum(Pt) with 0.5 at% via an impregnation approach to synthesize Pt/LaOx(OH)y catalysts.However,we find that these catalysts perform a poor stability for the CO oxidation reaction.The fresh and used samples were comprehensively characterized by multiple techniques including power X-ray diffraction(XRD),X-ray absorption fine structure(XAFS),transmission electron microscopy(TEM),temperature-programmed reduction by carbon monoxide(CO-TPR) and thermogravimetric analysis(TGA),to demonstrate that the oxidized platinum atoms or clusters,without any component of Pt-Pt metallic bond,are highly dispersed on the surface of LaOx(OH)y.Furthermore,the as-formed lanthanum carbonate(La2O2CO3) during the exposure to ambient circumstances or in the reaction atmosphere of CO+O2,severely impair the reactivity of Pt/LaOx(OH)y.On the basis of the obtained experimental results,we have drawn a conclusion that the oxidized PtOx atoms or PtxOy clusters are the active species for CO oxidation,while the formation of lanthanum carbonate is the origin of deactivation on reactivity. 相似文献
29.
30.
赵红凌 《理化检验(物理分册)》2006,42(8):428-429,415
化学溶解法是检验钢板镀锌层质量的一个主要手段。取不同的腐蚀液对镀锌层质量的影响进行了试验和对比。结果表明,选择盐酸-乙二胺(缓蚀剂)溶解锌层,锌层溶解后钢板表面光洁,所得结果的精确度令人满意。 相似文献