共查询到19条相似文献,搜索用时 187 毫秒
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采用电化学直流极化和交流阻抗技术 ,在有光照和黑暗条件下分别研究了半导体硅片在稀释氢氟酸溶液中的电化学特性 .两种电化学技术均对溶液中含有的微量铜 (1 0 - 9wt % -浓度水平 )非常敏感 ,但仅对溶液中的 1 0 - 6 wt % -浓度水平的非离子型表面活性剂敏感 .结果表明 ,有光照条件下在硅 /溶液界面上极易发生电化学反应 ,且该反应对硅表面性质起主导作用 . 相似文献
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通过电化学交流阻抗法研究了3种金属酞菁类大环化合物(FePc, CoPc, FeCoPc2)在碱性溶液中对氧气还原反应(ORR)的电化学催化行为, 各电极的交流阻抗 Nyquist 图谱在高频区和低频区均呈现出2个较明显的半圆和半圆之间(中频区)的压扁的弧形, 采用Zsimpwin阻抗谱分析软件对-02 V(vs. Hg/HgO)电位下的各交流阻抗谱进行等效电路拟合, 提出空气电极ORR反应的等效电路, 并对等效电路中各动力学参数进行了解释, 通过分析得出金属酞菁在碱性溶液中对ORR催化反应是一个伴随中间产物HO-2的2电子转移过程. 同时, 等效电路的拟合结果表明, FeCoPc2/C作为ORR催化剂对减小Rc+Rct效果比FePc/C和CoPc/C明显, 具有更高的催化活性. 相似文献
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采用微波等离子体化学气相沉积法在本征硅上制备掺硼金刚石膜/碳膜平面式复合电极,其中硅片的一面为掺硼金刚石膜,另一面为碳膜。通过SEM和拉曼光谱分析了薄膜的表面形貌和成分,掺硼金刚石膜为纳米级金刚石,碳膜表面有均匀分布的凹坑;利用四探针、循环伏安法和交流阻抗法表征电极导电性和电化学性能,随着沉积时间增加,电极方阻减小;在铁氰化钾溶液中电极发生准可逆氧化还原反应,电势差为119mV,在103Hz附近阻抗为113Ω;多巴胺的检测限为5μmol·L-1。 相似文献
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铜在离子选择性涂层下腐蚀行为的阻抗谱研究 总被引:1,自引:0,他引:1
用电化学交流阻抗技术研究了涂装不同离子造反性涂层的铜电极在3%NaCl溶液中的腐蚀行为,悄同涂装体系的阻抗谱特征,建立了相应的等 电路模型,由阻抗数据解析的结果,讨论了不同离子选择性涂层对铜的防蚀性能。 相似文献
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镀液中金属杂质离子对电镀镍层性能的影响 总被引:1,自引:0,他引:1
向镍电镀原液中引入2 g/L的Co~(2+),Cr3+,Mn~(2+),Fe~(2+),Cd~(2+),Zn~(2+)等离子,通过电镀得到不同的镀层.X射线衍射(XRD)、X射线光电子能谱(XPS)及扫描电子显微镜(SEM)的结果表明,不同金属离子对镍沉积影响不同,金属杂质离子的存在会使镀层中晶粒尺寸变小,影响镍镀层的均匀性和致密度.通过阴极极化曲线、计时电位和交流阻抗等方法探讨了含有不同金属杂质的镀液在电镀过程中电化学行为的规律性.通过镀液的浓度梯度、耐腐蚀、耐热循环及耐高温等实验获得了不同条件下金属杂质在镀液中所允许的浓度范围. 相似文献
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探索了一种储氢合金表面修饰的新方法. 在HF和CuSO4的混合溶液中对MH/Ni电池负极材料AB5型储氢合金进行表面处理, 研究了HF含量对反应的影响;考察了铜颗粒沉积量对表面修饰的影响;测试了修饰后合金电极的电化学性能;应用交流阻抗分析了表面修饰对合金性能影响的作用机理. 电化学测试结果表明, 表面修饰后合金电极具有更好的高倍率放电能力和循环稳定性. EIS分析结果表明, 表面修饰使合金的活性增强, 导电性提高, 欧姆阻抗及电化学阻抗显著降低. 因此, 这种新型表面修饰方法可以有效地改善合金的电化学性能, 使之更好地满足电动车用动力型电源的要求. 相似文献
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A photoassisted anodization process to fabricate arrays of uniform and straight macropores at selected areas of a Si wafer surface was developed. The front- and backside surfaces of n-type Si(100) wafers were coated with a thin Si(3)N(4) layer, and the frontside layer was micro-patterned using photolithography and reactive ion etching to form an array of microscopic openings at selected areas. The inverted pyramid-shape micropits were formed at these openings by anisotropic etching using aqueous KOH solution; these pits act as the initiation sites for the anodization to form macropores. The electrochemical etching was carried out in aqueous HF solution under illumination from the backside of the wafer, on which Au/Cr electric contact was formed following removal of the Si(3)N(4) layer. To improve the uniformity of the formation condition of the macropores at the selected area, holes were area-selectively generated by controlling the illumination condition during the anodization. For this, micropatterns were formed on the Au/Cr layer at the backside surface, which were aligned to those at the frontside surface. The parameters, such as HF concentration, current density, and wafer thickness, i.e., hole diffusion length, were optimized, and the arrays of uniform and high-aspect-ratio macropores were formed at the selected area of the domain at the silicon surface. 相似文献
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本文采用市售纳米硅为硅源,以软化点低、得碳率高、价格便宜的煤沥青作为碳源,通过两步包覆法制备了煤沥青基硅/碳(Si/C/C)复合物,并研究其作为锂离子电池负极材料的电化学性能。 结果表明,所得复合物的粒径在300~350 nm间,Si纳米粒子被C包覆并相互连结成C-Si-C网络结构,其中Si含量为27%的硅/碳复合物(Si/C/C-27%)作为锂电池电极材料表现了良好的储锂性能。 在0.1 A/g的小电流密度下,Si/C/C-27%的放电比容量为1281 mA·h/g;在3 A/g的大电流密度下,其放电比容量仍能保持在582 mA·h/g,表现了良好的倍率性能。Si/C/C-27%在2 A/g的电流密度下经过100次的循环后其比容量保持率为76.61%,表现了良好的循环稳定性。 相比于煤沥青基碳的一次包覆所得的硅/碳复合材料(Si/C),Si/C/C有效提高了Si纳米粒子的导电性并抑制了其在嵌锂和脱锂过程中的体积膨胀。 本文提出的二次包覆的新方法为制备具有优异电化学性能的锂离子电池负极材料提供了新的研究思路。 相似文献
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Xing Xin Xiayin Yao Yiming Zhang Zhaoping Liu Xiaoxiong Xu 《Journal of Solid State Electrochemistry》2012,16(8):2733-2738
The nanostructured Si/graphite composites embedded with the pyrolyzed polyethylene glycol was synthesized from coarse silicon and natural graphite by a facile and cost-effective approach. The Si/C nanocomposite showed the fluffy carbon-coated structure, which was confirmed by the SEM and TEM measurements. The as-obtained Si/C nanocomposite, employed as anode material in lithium-ion batteries, exhibited significantly enhanced rate capability and cycling stability. The improved electrochemical stability of the composite was evaluated by EIS and galvanostatically charge/discharge test. A reversible capacities as high as 85% and 91% of the initial charge capacities, could be maintained for the Si/C nanocomposite electrode after 40 cycles under the high current densities of 500 and 1,000?mA?g?1, respectively. The relatively low cost and excellent electrochemical capability of the Si/C nanocomposite would well meet the challenge in rapid charge and discharge for large-size lithium-ion rechargeable batteries. 相似文献
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单晶硅是Eg为1.1eV的间接带隙半导体材料,在可见光区不发光,不能应用于光电子领域.但是,Canham 1990年首次发现[1],适当条件下形成的多孔硅在室温下就可发出强度能与Ⅲ-Ⅴ族半导体发光二极管相媲美的可见光。 相似文献
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本工作初步探讨了开路电位下对硅片进行预处理时多孔硅的形成过程 .电化学极化实验、扫描电镜和拉曼谱学的研究表明 ,预处理可以加速硅 /溶液界面上的化学或电化学反应 ,从而加快多孔硅的生长过程 ,最终导致光致发光的光谱红移 .多孔硅的厚度随预处理时间的增长而减小 相似文献
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《Electroanalysis》2018,30(2):238-249
A copper nano particles and cerium (IV) oxide modified carbon nanotube based composite on glassy carbon electrode (Cu−CeO2/MWCNT/GCE) was fabricated for simultaneous determination of guanine and adenine. The surface morphology, chemistry and conductance of the prepared electrodes were characterized by scanning electron microscopy (SEM), energy dispersion X‐ray (EDX), X‐Ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The Cu−CeO2/MWCNT/GCE improved electrochemical behaviour of guanine and adenine compared to other electrodes. The modified electrode was also used for individual and simultaneous determination of guanine and adenine. Under optimized conditions, the calibration curves were obtained linearly in the range of 0.20 to 6.00 μM for the guanine and 0.10 to 8.0 μM for the adenine by differential pulse voltammetry. The limits of detection of guanine and adenine were calculated as 0.128 and 0.062 μM, respectively. Interferences studies were also performed in the presence of inorganic and organic compounds. Moreover, the determination of guanine and adenine contents were carried out in a calf thymus DNA sample by the developed method with satisfactory results. 相似文献
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Youliang Zhang Han Chen Ningbo Bai Kaixiong Xiang Wei Zhou 《Russian Journal of Electrochemistry》2016,52(2):181-184
Silicon/carbon microrods are co-deposited on copper substrate and graphite spheres surface using dimethyl dichlorosilance as carbon and silicon precursor. The obtained composites are characterized by X-ray diffraction and scanning electron microscopy. The experimental results show that silicon/carbon microrods deposited on the copper substrate, whose diameter is about 500 nm, are accumulated into sisallike morphology, those deposited on the graphite spheres surface form hedgehog-like feature, whose diameter is about 200 nm and whose top is like cauliflower. When current density of 50 mA/g is applied, charge capacity of silicon/carbon microrods is 1492 mA h/g (deposited on copper substrate) and 693 mA h/g (deposited on the graphite spheres surface). Moreover, silicon/carbon microrods deposited on the graphite spehres and copper substrate respectively deliver the capacity of 592, 985 mA h/g, and display no capacity decay at all after the 20 cycles, when cycled under current density of 500 mA/g. 相似文献