Self-repairing Al_(2)O_(3)-TiO_(2)coatings fabricated through plasma electrolytic oxidation with various cathodic pulse parameters

The influence of cathodic pulse parameters was evaluated on plasma electrolytic oxidation(PEO)coatings grown on 7075 aluminum alloy in a silicate-based electrolyte containing potassium titanyl oxalate(PTO)using pulsed bipolar waveforms with various cathodic duty cycles and cathodic current densities.The coatings were characterized by SEM,EDS,and XRD.EIS was applied to investigate the electrochemical properties.It was observed that the increase of cathodic duty cycle and cathodic current density from 20%and 6 A/dm^(2) to 40%and 12 A/dm^(2) enhances the growth rate of the inner layer from 0.22 to 0.75μm/min.Adding PTO into the bath showed a fortifying effect on influence of the cathodic pulse and the mentioned change of cathodic pulse parameters,resulting in an increase of the inner layer growth rate from 0.25 to 1.10μm/min.Based on EDS analysis,Si and Ti were incorporated dominantly in the upper parts of the coatings.XRD technique merely detectedγ-Al_(2)O_(3),and there were no detectable peaks related to Ti and Si compounds.However,the EIS results confirmed that the incorporation of Ti^(4+)into alumina changed the electronic properties of the coating.The coatings obtained from the bath containing PTO using the bipolar waveforms with a cathodic duty cycle of 40%and current density values higher than 6 A/dm^(2) showed highly appropriate electrochemical behavior during 240 d of immersion due to an efficient repairing mechanism.Regarding the effects of studied parameters on the coating properties,the roles of cathodic pulse parameters and PTO in the PEO process were highlighted.

新生态MnO_2对水溶性阴离子染料废水的脱色研究

以各种水溶性染料,包括直接染料、酸性媒介染料、活性染料的废水为实验对象,系统研究了新生态MnO2在染料废水脱色过程中的作用。结果表明,受试染料的脱色效果均十分显著,最佳pH≤2.5,脱色作用的机理在于MnO2的表面羟基在酸性条件下发生质子化,可以与阴离子染料以库仑力结合而将其吸附除去。

超级电容器电极材料纳米α-MnO_2的制备及性能研究

用溶胶-凝胶法和沉淀法制备了具有纳米结构的α-MnO2,分别对其进行X-射线衍射(XRD)、扫描电镜(SEM)、循环伏安(CV)等测试,结果发现溶胶-凝胶法所合成的材料是由粒径为60nm的微粒组成,沉淀法所合成的材料粒径在80nm范围.并研究了不同配比的α-MnO2和活性炭组成的复合电极在各种浓度的电解液中的循环伏安性能,发现当电极中α-MnO2质量百分含量为40%～60%时,在0.5mol/LNa2SO4、2.0mol/L(NH4)2SO4、1.0mol/LKCl溶液中的比电容较高,其中在2.0mol/L(NH4)2SO4溶液中的比电容最高可达108.26F/g.

水热温度对MnO_2纳米线结构和电容性能的影响

以KMn O4和Mn SO4为原料,采用水热法合成超级电容器电极材料纳米MnO_2,采用X射线衍射（XRD）、扫描电镜（SEM）、比表面积测试、循环伏安、恒流充放电和电化学阻抗等方法测试MnO_2的结构和电容性能。结果表明,采用水热法可以合成直径为10~90 nm,长度为1~3 cm的α-MnO_2纳米线;水热温度对MnO_2纳米线的晶粒和形貌影响显著,但不改变MnO_2的晶型;随水热温度升高,MnO_2纳米线的晶粒逐渐长大,同时变长变粗,导致比表面逐渐降低;MnO_2纳米线的比电容随水热温度升高呈先增大后减小,当水热温度为140℃时比电容最大,为227 F/g,同时表现出良好的倍率性能。

纳米MnO_2超级电容器电解液性能研究

利用溶胶凝胶法制备纳米MnO2,由该样品制成的电极在(NH4)2SO4电解液中表现出良好的电容性能。考虑到(NH4)2SO4溶液对集流体泡沫镍的腐蚀,开展了向(NH4)2SO4溶液中加入添加剂(Na2SO4、K2SO4、MgSO4)以减缓(NH4)2SO4对泡沫镍腐蚀的研究,研究了添加剂的添加量和电解液的摩尔浓度对MnO2电极的电化学性能和对泡沫镍的腐蚀程度的影响。发现采用MgSO4的摩尔百分含量为50%、电解液的摩尔浓度[以(NH4)2SO4+ 添加剂的摩尔浓度计]为0.5 mol·L-1的电解液基本上不降低MnO电极的电化学性能,却大幅降低对泡沫镍的腐蚀程度。

碱性Zn/MnO_2电池的技术进步与发展潜力(1)

介绍了近年来碱性Zn／MnO2电池的工艺进展，在正极中使用高活性MnOZ2较细的石墨粒子；在负极中使用细粒径Zn粉合金，去Hg、Cd、Pb，以及适宜的胶凝剂、缓蚀剂；在简壳上减小筒壁厚度，使用适宜涂层；使用多孔更薄加有表面活性剂的隔膜；以及其他可提高碱性Zn／MnO2电池性能的措施。指明碱性Zn／MnO2电池仍有较大的发展潜力。

电沉积法制备PANI/MnO_2/石墨烯复合材料及其电化学性能研究

采用简便的脉冲电沉积方法一步合成了呈现层-层分布的三维立体结构的PANI/MnO_2/石墨烯三元复合材料,利用XRD和FT-IR等研究了复合物的结构和组成,SEM和TEM表征了复合物的形貌。同时,通过恒流充放电和循环伏安测试研究了该复合物的电化学性能。结果表明,0.5 A·g^(–1)电流密度下的比容量可达1 120 F·g^(–1),且1 000次循环的稳定性高达99%。出色的超电容性能主要源于石墨烯作为基体,其上均匀分布棒状结构的PANI,MnO_2纳米粒子均匀分布于PANI纳米棒上,形成了一种分级的特殊结构。

超级电容器用(RuO_2/MnO_2)·n H_2O复合电极的研究

采用电沉积法制备超级电容器用钽基(RuO_2/MnO_2)·n H_2O复合薄膜电极材料,制定钽箔基体的预处理方法、复合溶液主盐的配置比例、电沉积参数和热处理参数。重点研究了初始沉积液中Mn^(7+)与Ru^(3+)摩尔浓度比以及不同热处理参数对((RuO_2/MnO_2)·n H_2O复合薄膜附着力与电学性能的影响。借助扫描电镜、X射线衍射仪对薄膜的形貌和物相分析,用电化学工作站对该复合薄膜电化学性能进行测量。实验结果表明,当初始沉积液中Mn^(7+)与Ru^(3+)摩尔比为3:1,热处理温度为250℃,时间为2.5h,所制备出的复合电极薄膜具有较好的附着力和较高的比电容,分别为14.8MPa与418F/g。该复合薄膜在不同扫描速率下的循环伏安图具有高度可逆的氧化和还原曲线,说明其具有很明显的电容特性,是一种较为理想的RuO_2基复合薄膜。

新型稀土固体超强酸SO_4^(2-)/MnO_2/La^(3+)的合成研究

以硫酸锰和硝酸镧为原料,采用共沉淀-浸渍法制备不同比例的SO^(2-)_4/MnO_2/La^(3+)。以催化合成乙酸苄酯为探针反应,考察H_2SO_4浓度、La(NO_3)_3的质量分数、焙烧温度、焙烧时间等因素对其催化活性的影响。结果表明,催化剂制备的最佳条件为:硝酸镧的加人为硫酸锰的3%(质量分数),浸渍浓度为1 mol·L^(-1)的H_2SO_4,焙烧温度为450℃,焙烧时间3 h,酯化率到达最大,为89.7%。

λ-MnO_2及掺杂λ-MnO_2在LiNO_3电液中的电化学性质研究

利用恒电流放电、循环伏安、ＩＣＰ、ＸＲＤ 等技术研究了λＭｎＯ２ 及掺铋、掺钡λＭｎＯ２ 在５ ｍｏｌ·Ｌ－ １ＬｉＮＯ３ 水溶液中的放电性能。得出λＭｎＯ２ 在中性电液中的恒电流放电曲线为三个明显的放电平台，放电机理与λＭｎＯ２ 在有机电液中的放电机理相似。循环伏安测试表明放电的可逆性差，经过掺杂后样品在ＬｉＮＯ３ 中的循环性有一定的改善。

Alternative Strategy for Development of Dielectric Calcium Copper Titanate‑Based Electrolytes for Low‑Temperature Solid Oxide Fuel Cells

The development of low-temperature solid oxide fuel cells(LT-SOFCs)is of significant importance for realizing the widespread application of SOFCs.This has stimulated a substantial materials research effort in developing high oxide-ion conductivity in the electrolyte layer of SOFCs.In this context,for the first time,a dielectric material,CaCu_(3)Ti_(4)O_(12)(CCTO)is designed for LT-SOFCs electrolyte application in this study.Both individual CCTO and its heterostructure materials with a p-type Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2−δ)(NCAL)semiconductor are evaluated as alternative electrolytes in LT-SOFC at 450–550℃.The single cell with the individual CCTO electrolyte exhibits a power output of approximately 263 mW cm^(-2) and an open-circuit voltage(OCV)of 0.95 V at 550℃,while the cell with the CCTO–NCAL heterostructure electrolyte capably delivers an improved power output of approximately 605 mW cm^(-2) along with a higher OCV over 1.0 V,which indicates the introduction of high hole-conducting NCAL into the CCTO could enhance the cell performance rather than inducing any potential short-circuiting risk.It is found that these promising outcomes are due to the interplay of the dielectric material,its structure,and overall properties that led to improve electrochemical mechanism in CCTO–NCAL.Furthermore,density functional theory calculations provide the detailed information about the electronic and structural properties of the CCTO and NCAL and their heterostructure CCTO–NCAL.Our study thus provides a new approach for developing new advanced electrolytes for LT-SOFCs.

负载纳米MnO_2针织物分解溶液中甲醛效率分析

以高锰酸钾和乙醇为原料采用原位液相沉淀法制备了负载纳米MnO_2针织物,通过红外光谱、X-射线衍射光谱和扫描电镜对负载纳米MnO_2针织物进行了表征,分析了负载次数、甲醛初始浓度、反应时间、洗涤次数和重复使用对甲醛分解效率的影响。结果表明,负载纳米MnO_2针织物对甲醛具有较优的氧化分解性能;室温条件下,负载7次纳米MnO_2针织物17 h后即可将浓度为5.00 mg/L甲醛溶液中的甲醛全部分解去除;负载5次纳米MnO_2针织物反应24 h,甲醛去除率为96.5%,且随反应时间延长,所有样品都可将甲醛分解去除;经10次水洗后MnO_2脱落量较小,重复试验结果表明负载纳米MnO_2针织物可循环重复利用。

Zn/MnO_2电池的电解质溶液

对Zn/MnO2 电池所用电解质溶液的发展及其导电性、杂质与净化和添加剂进行了讨论 ,并指出电池的放电特征主要取决于电解质的性质 ,建议对电池的放电特点加强宣传。

不同形貌MnO_2的制备及其电化学性能

用化学共沉淀法和水热法制备了海胆型和纳米线型的MnO_2。采用X射线衍射仪（XRD）、扫描电镜（SEM）对电极材料的物相和形貌进行表征。采用电化学阻抗、循环伏安和恒电流充放电对其进行电化学性能测试。结果表明，采用相同材料不同制备方法得到的MnO_2具有不同的形貌。化学共沉淀法制备的海胆型MnO_2，其直径约为300～500nm；水热法制备的纳米线型MnO_2，其直径约为10～30nm，长度约为100～500nm。两种形貌的MnO_2在6mol·L^-1KOH溶液中具有良好的电容特性，1A·g^-1的电流密度下，海胆型MnO_2的比电容为539F·g^-1；纳米线型MnO_2的比电容为375F·g^-1经过1000圈的循环后，海胆型MnO_2仅损失了15％的比容量。

α-MnO_2/石墨烯纳米复合物的合成及其电化学性能研究

通过回流原位复合方法制备了α-MnO2/石墨烯纳米复合物。通过X-射线衍射(XRD)和热重方法分别对样品进行晶体结构分析和石墨烯含量的计算。采用恒流充放电和交流阻抗法研究石墨烯的添加对α-MnO2负极材料电化学性能的影响,结果表明,在本实验条件下,添加13.5%石墨烯的纳米复合物具有最优的电化学性能,在电流密度为50mA/g时,循环15周之后,充放电容量分别比纯α-MnO2提高了94mAh/g和117mAh/g。随着石墨烯添加量的增加,复合电极的电荷转移电阻减小,交换电流密度增加,有利于电化学反应的进行。

超级电容器用MnO_2基纳米复合材料的进展

介绍二氧化锰(MnO_2)的结构及储能机理,综述近年来MnO_2作为赝电容材料,通过不同材料改性,以提高电化学性能的研究进展。这些材料主要有碳材料、导电聚合物、金属和金属氧化物/硫化物等。展望由MnO_2基纳米复合材料构建的核壳结构的发展趋势。

A symmetric MnO_2/MnO_2 flexible solid state supercapacitor operating at 1.6V with aqueous gel electrolyte

The demand of microelectronic devices postulated high energetic flexible energy storage devices. Flexible solid state supercapacitor is flawless possible candidate to fulfill the requirement of microelectronic devices. This investigation provides practical evidence of the use of flexible solid state supercapacitors based on MnOelectrodes with polyvinylpyrrolidone(PVP)-Li ClOgel electrolyte. Initially, different acid mediated growths of MnOhave been carried. Later, the electrochemical performances of MnOelectrodes have been carried out. Impressively, the fabricated symmetric flexible solid state supercapacitor(FSS-SC) device demonstrates the highest operating potential window of 1.6 V with extended cycling stability. Moreover, the cell exhibits high energy density of 23 Wh/kg at power density of 1.9 k W/kg. It is interesting to note that the device shows excellent flexibility upon bending at angle of 180° for number of times. These results clearly evidenced those symmetric FSS-SC devices based on MnOelectrodes are promising energy storage devices for microelectronic applications.

Influence of MnO_2 Mineralizer on the Crystal Structure,Properties of SiC Kiln Furniture Bonded with Fine Silicon Powder

The properties of SiC kiln furniture bonded with fine silicon powderare related to the bonder’s crystal structure. At high temperature, it will crystallize ina-cristobalite with great bulk effect. MnO2 mineralizer can make a-cristobalite convertto a-tridymite whose bulk effect is small. The crystal structure and its amount were investigated with XRD technique. The influence of different amounts of MnO2 on thecrystal structure and polycrystal transformation, and that of crystal structure on theproperties of kiln furniture were studied. The best proportion of MnO2 added was determined to be 2.0%.

Effects of Yttrium Ion on Formation Mechanism of ZrO_2-Y_2O_3 Ceramic Coatings Formed by Plasma Electrolytic Oxidation on Al-12Si Alloy

ZrO2-Y2O3 ceramic coating was produced by plasma electrolytic oxidation （PEO） on ZAlSil2Cu3Ni2 alloy. The microstructure and phase composition of the coating were investigated by SEM and XRD.： The results show that adding an appropriate amount of yttrium ion can improve the growing rate of ceramic coating at different oxidation stages and decrease arc voltage. The thickness of ZrO2-Y2O3 coating is 16 μn thicker than that of ZrO2 coating and the maximum oxidation rate improves by 0.6 μm/min. In addition, the arc voltage decreases from 227 to 172 V. It can be seen that the rate of oxidation firstly increases to some extent and then decreases with the content of yttrium ion increasing. The growth rate reaches the maximum while the content of yttrium ion is 0.05 g-L-1The maximum thickness is 90 μm.Compared to ZrO2 coating, the micropores of ZrO2-Y2O3 coating are less and the ceramic layer is repeatedly deposited by ZrO2 and Y2O3 ceramic particles. Meanwhile, the binding force between coating and substrate is better and the coating is uniform and compact. The ceramic layer is mainly composed of c-Y0.15Zr0.85O1.93□0.07, m-ZrO2, α-Al2O3, ,γ-Al2O3 and Y2O3. It is indicated that ZrO2 has beert fully stabilized by yttrium ion through the formation of solid solution.

Incorporation mechanism of colloidal TiO_(2) nanoparticles and their effect on properties of coatings grown on 7075 Al alloy from silicate-based solution using plasma electrolytic oxidation

Plasma electrolytic oxidation(PEO)was applied using a pulsed unipolar waveform to produce Al_(2)O_(3)−TiO_(2) composite coatings from sol electrolytic solutions containing colloidal TiO_(2) nanoparticles.The sol solutions were produced by dissolving 1,3,and 5 g/L of potassium titanyl oxalate(PTO)in a silicate solution.Scanning electron microscopy,energy dispersive spectrometry,X-ray diffraction,and Raman spectroscopy were applied to characterizing the coatings.Corrosion behavior of the coatings was investigated using polarization and impedance techniques.The results indicated that TiO_(2) enters the coating through all types of micro-discharging and is doped into the alumina phase.The higher level of TiO_(2) incorporation results in the decrease of surface micro-pores,while the lower incorporation shows a reverse effect.It was revealed that the higher TiO_(2) content makes a more compact outer layer and increases the inner layer thickness of the coating.Electrochemical measurements revealed that the coating obtained from the solution containing 3 g/L PTO exhibits higher corrosion performance than that obtained in the absence of PTO.The coating produced in the absence of PTO consists of γ-Al_(2)O_(3),δ-Al_(2)O_(3) and amorphous phases,while α-Al_(2)O_(3) is promoted by the presence of PTO.