共查询到16条相似文献,搜索用时 187 毫秒
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本文使用线性电位扫描法还原预恒电位法氧化形成的阳极膜,研究电位对Pb-7Sb,Pb-7Sb-0.3Ag和Pb-5Sb-0.2As三种合金在30℃,4.5MH2SO4溶液中的阳极膜的生长速度的影响,在铅锑合金中添加银可降低合金阳极膜的生长速度,但在高电位1.4V(vs.Hg2SO4电极时,Pb-7Sb-0.3Ag合金上的PbO2膜的生长速度在上述三合金中居首,这可能是由于在银上的氧析出超电势较低的缘故,本文讨论了这种阳极膜的生长机理。 相似文献
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硫酸溶液中铅阳极膜研究的几个问题(二) 总被引:5,自引:0,他引:5
硫酸溶液中铅阳极膜研究的几个问题(二)①柳厚田*王群洲万咏勤周伟舫(复旦大学化学系,上海200433)蔡文斌(厦门大学化学系,厦门361005)在硫酸溶液中开始生长阳极Pb(Ⅱ)膜后不久,表面即形成PbSO4半透膜,该膜仅H+、OH-和H2O可通过,... 相似文献
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铅锑电极上PbO_2生长过程的阻抗跟踪法研究韦国林,杨鸿兴,王家荣(上海大学嘉定校区化学系,上海,201800)利用交流阻抗技术研究Pb/H2SO4体系中电化学过程,通常采用某一等效电路,并对所得的多频率阻抗频谱进行拟合处理,由此获得相关电化学信息。?.. 相似文献
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铅锑合金在硫酸溶液中的阳极膜I.早期阳极膜生长动力学 总被引:2,自引:0,他引:2
本文用线性电位扫描法(20mV.s-1),自I.2V(vs.Hg/Hg2SO4)扫描至-1.2V,研究了三种铅锑合金在3.5MH2SO4溶液中(30℃),经一定时间(60,600,1200,)和240Os)1.2V阳极极化形成的阳极膜,该阳极膜的主要成分可能是PbO.PbSO4,其表面为PbO2.本文摊导出与实验一致的此种阳极膜的生长学方程式,并利用该式测得氧原子在阳极膜中的扩散系数。 相似文献
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Pb及Pb-7w/O Sb合金在氧析出电位区生长的阳极膜 总被引:1,自引:0,他引:1
分别测量了Pb及Pb-7w/0Sb在4.5mol.dm^-^3H^2SO~4(30℃)中于1.3和1.5V(vs.Hg/Hg~2SO~4/4.5mol.dm^-^3H^2SO~4)下在不同时间生长的阳极膜的交流阻抗谱, 并使用线性电位扫描法分析了上述阳极膜的相组成。讨论了上述阳极膜进行的电化学反应的机理, 并据此提出它们的等效电路。实验结果表明上述阳极膜的真实表面积随生长时间而增加, 该膜多孔, 主要由外层为PbO~2的PbO.PbSO~4微粒组成, 锑能显著抑制PbO~2的生长, 特别是在1.3V时。 相似文献
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The effects of sq. wave potential on the growth rate of the anodic films on Pb-7 Sb and Pb-5 Sb-0.2 As in 4.5 mol/dm3 H2SO4 at 30?were studied by a cathodic linear potential sweep method. By applying the sq. wave potential with period of 3600 s, the potentials of the lead alloys were cycled between that corresponding to the charged conditions of a Pb-acid battery (3 different charge potentials were studied: 1.4, 1.3 and 1.2 V vs. Hg/Hg2SO4, resp.) and that to the discharged condition (1.0 V). The anodic films contain grains with many voids among them as observed with SEM. The surface layer of the grain is PbO2, however, the major constituent of the grain is probably PbO.PbSO4. The relation between the quantity of electricity used to form PbO.PbSO4 and the no. of charges is linear for a certain no. of charge-discharge cycles. The conductance of the film is mainly due to the high conductivity of the PbO2 boundary layers of the grains, especially when the grains are in close contact with one another under pressure. 相似文献
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测取了硫酸浓度为0.5~5.1mol.dm^-^3、扫描速度为1~70mV/s的铅的循环伏安曲线.得到两个PbO~2形成峰I和II,相应地假设为PbO和PbSO~4的氧化.在较低的扫描速度下以及稀硫酸溶液中,峰值电位ψpI与扫描速度S几乎无关,峰值电流ipI近似地与(S)^1/2呈直线关系,并与PbSO~4在硫酸溶液中的溶解度相应,所以过程可能受Pb^2+离子在表面膜孔隙内的扩散所控制.在较高的扫描速度下,δψpi/δlogS=50mV,属于不可逆过程,对于峰II PbSO~4的氧化过程也进行了初步讨论. 相似文献
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Masato Takeuchi Kouichirou Tsujimaru Kenji Sakamoto Masaya Matsuoka Hiromi Yamashita Masakazu Anpo 《Research on Chemical Intermediates》2003,29(6):619-629
Platinum-loaded titanium oxide thin-film photocatalysts were prepared by using an ionized cluster beam (ICB) deposition method and a RF magnetron sputtering (RF-MS) deposition method as dry processes. From the results of the photocatalytic oxidation of acetaldehyde with O2 under UV light irradiation, small amounts of Pt loading (less than 10 nm film thickness) were found to dramatically enhance the photocatalytic reactivity. However, when TiO2 thin films were loaded with relatively larger amounts of Pt (more than 30 nm as the film thickness), the photocatalytic reactivity became lower than for the pure TiO2 thin films. Moreover, investigations of the ratio of Pt loaded onto the surface of the thin film catalysts by XPS measurements revealed that the small amounts of Pt loaded exist as very small clusters working to efficiently enhance the charge separation, whereas, large amounts of Pt covers the entire surface of the TiO2 thin films, resulting in a decrease of the photocatalytic reactivity. 相似文献