一维纳米Co_3O_4,Ag/Co_3O_4及CuO/Co_3O_4的合成与电催化性能(英文)

采用水热合成法制备了Co3O4及复合Ag/Co3O4、CuO/Co3O4一维纳米产品。用XRD,FE-SEM和TEM手段对产品进行了表征。采用循环伏安法研究了合成产品修饰的玻碳电极在碱性溶液中对对硝基苯酚的电催化还原性能。与裸玻碳电极相比,1mmol·L-1的对硝基苯酚在用Co3O4、特别是CuO/Co3O4修饰的玻碳电极上还原的峰电流明显增大,用Ag/Co3O4(Ag/Co原子比分别为1∶5和2∶5)修饰的玻碳电极催化还原对硝基苯酚时,尽管还原峰电流增大不是太大,但其峰电位明显降低(分别降低0.265和0.371V)。     

纳米片聚结Co3O4微球催化甲苯燃烧

采用乙二胺辅助的水热法制备了纳米片聚结的Co₃O₄微球. 利用多种分析技术表征了其物化性质,并评价了其对甲苯燃烧的催化活性. 结果表明,由添加1.0 ml乙二胺经140 ℃水热处理12 h后制得的Co₃O₄样品呈纳米片聚结的微球状表面形貌. Co₃O₄微球样品的比表面积约为66 m² g^-1. 与体相Co₃O₄样品相比,Co₃O₄微球样品具有较高的氧吸附物种浓度和较好的低温还原性. 当空速为20000 ml g^-1 h^-1时,在Co₃O₄微球样品上甲苯转化率达到50%和90%时的反应温度分别为230和254 ℃. 这与该样品具有较大的比表面积、较高的氧吸附物种浓度和较好的低温还原性相关.     

Zur Bestimmung des Kobalts als Co3O4

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层状Co3O4的制备及其电化学电容行为

以P123为模板水热合成制备了Co₂(OH)₂CO₃前驱体，200 ℃热处理后得到了具有层状结构的Co₃O₄。循环伏安、恒流放电等电化学测试表明，200 ℃所得Co₃O₄电极在6 mol·L^-1 KOH溶液中和-0.1～0.5 V(vs Ag/AgCl)电位范围内，具有较好的循环稳定性能，单电极比电容达到505 F·g^-1。     

Synthesis of morphology-controllable mesoporous Co3O4 and CeO2

Recently, extensive works have been devoted to the morphology control of mesoporous materials with respect to their use in various applications. In this paper, we used two kinds of mesoporous silica, SBA-15 rods and spheres as hard templates to synthesize morphology-controllable mesoporous metal oxides. By carefully controlling the loading of metal precursors in the mesopores of the hard template, mesoporous Co₃O₄ and CeO₂ with different morphologies, such as micrometer-sized rod, hollow sphere, saucer-like sphere, and solid sphere were conveniently obtained. The structural properties of these materials were characterized by XRD, BET, SEM and TEM. In addition, it is found that the differences observed in the textural properties of the two mesoporous metal oxides nanocasted from the same template can be attributed to the properties of metal precursors and the interaction between metal oxide and SiO₂. Thus-obtained mesoporous metal oxides with such special morphologies may have a potential application in the field of environmental catalytic oxidation.     

Catalytic oxidation of methane over Pd/Co3O4

The catalytic activity of Pd/Co₃O₄ toward methane oxidation has been examined in this study as a function of Pd loading, reaction temperature, space velocity and methane concentration in the reaction gas mixture. The bare oxide is quite active achieving a 100% methane conversion at 480°C under the reaction conditions used. The catalyst with the highest Pd loading tested of 10 wt.% yields the best activity curve, but the 5 wt.% Pd/Co₃O₄ catalyst performs nearly as well. Complete conversion for this catalyst is attained at 300°C and the activity remains stable over a 90-min test period.     

Magnetic Co3O4 nanowires,preparation and properties

The Co₃O₄ nanowires have been successfully synthesized via modified template method.The as-prepared products have been characterized by EDS,TEM and HRTEM analysis.The magnetic behavior of it is investigated by a magnetic property measurement system.The nanowires exhibit some novel magnetic properties,which are different from its bulk material.The temperature dependence curves of magnetization in zero-field-cooling and field-cooling exhibit two peaks of antiferromagnetic at blocking temperature of～23 K and～31 K,respectively.The field dependent M（H） curves of the Co₃O₄ nanowires at T = 5 and 300 K both exhibit PM properties.Moreover,the diameter of nanowires is hence determined according to the finite size effect as approximately 7-11 nm,in consistent with the characterizations by HRTEM.     

Co3O4纳米片的制备及其电化学电容性能

以配位超分子化合物为前驱物,通过液相氧化分解得到了六方形CoOOH纳米片,进而在空气中热处理制得了Co₃O₄纳米片。利用XRD、TEM、FESEM对CoOOH和Co₃O₄纳米片的结构和形貌进行了表征。电化学测试表明,Co₃O₄纳米片电极在6 mol·L^-1 KOH溶液中表现出良好的电化学电容特性,在电流密度为1 A·g^-1其单电极比容量可达到227 F·g^-1。     

溶剂热法合成纳米立方状Co3O4及其电容特性研究

以聚乙二醇为分散剂，在水-正丁醇体系中采用溶剂热法合成纳米立方状Co₃O₄。采用IR、XRD和TEM等手段对前驱物及产物的物相和形貌进行表征，对溶剂热法合成Co₃O₄的反应机理进行初步研究，并以Scherrer公式计算出样品平均晶粒尺寸为21.6 nm。通过循环伏安、恒流充放电、交流阻抗等测试对Co₃O₄电极的电化学性能进行表征。结果表明，在2 mol·L^{-1相似文献}   

聚合物燃烧方法制备Co3O4纳米粒子

纳米粒子因其独特的物理化学特性成为近年来材料科学领域的研究热点。制备方法是获得性能优越材料的关键。Co3O4具有正常的尖晶石结构，Co^2 占据八面体位置，在空气中低于800℃时十分稳定，是优良的催化剂材料^[1,2]，采用燃烧方法可通过控制反应条件在不发生沉淀的情况下获得化学组成均匀的复合氧化物粉体^[4-7]，本利用聚合物燃烧方法探索制备粒径均匀，分散性好的立方Co3O4纳米粒子，选择聚乙烯醇（PVA）的原因是其分子内包含大量的羟基极性基团，能与金属离子尤其是过渡金属离子形成良好的化学键，促使金属离子在PVA高分子的网络中均匀螯合分布，有利于最终形成分散性良好的粉体。     

Co3O4纳米线的丙三醇辅助合成及其电化学性质

以硝酸钴和丙三醇为反应物通过反应条件的改变控制制备出Co3O4纳米线.利用粉末X射线衍射(XRD),扫描电子显微镜(SEM)和透射电子显微镜(TEM)对产物的形貌与结构进行了表征.实验发现,在低扫描速率下,Co3O4纳米线电极的循环伏安(CV)曲线呈现出两对氧化还原峰.恒电流充放电实验中,氧化钴纳米线电极在1A.g-1电流密度下的电容为163F.g-1;在1和4A.g-1条件下,其容量随循环次数的增加先上升后下降,1000次充放电循环后容量保持率分别在98%和80%以上,继续增加循环次数则容量下降比较明显.锂离子电池性质测试中,氧化钴纳米线的放电容量为1124mAh.g-1,然而放电容量随循环次数增加下降较快.基于实验结果,对Co3O4纳米线的形成机理及其结构与电化学性质之间的关系进行了探讨.     

氮掺杂碳纳米管负载Co3O4氧还原电催化剂的制备与性能

以碳纳米管(CNT)为原料,通过负载维生素B₁₂,简单热解得到了一种氮掺杂碳纳米管(N/CNT)负载低含量Co₃O₄纳米颗粒的氧还原电催化剂(Co₃O₄@N/CNT)。得益于均匀分散的Co₃O₄纳米颗粒以及氮掺杂,Co₃O₄@N/CNT表现出了优异的氧还原催化性能,其半波电位达到了0.844 V(vs RHE),超越了商业Pt/C(0.820 V(vs RHE))。与Pt/C相比,基于Co₃O₄@N/CNT组装的锌-空气电池表现出了更优的放电性能和循环稳定性。     

Electrochemical deposition and properties of PbO2 + Co3O4 composites

Electrolysis of suspensions of Co₃O₄ particles in Pb²⁺-containing electrolytes has been used for depositing PbO₂ + Co₃O₄ composite layers on Ni rotating dise anodes. A sufficiently high angular speed of the electrode is necessary to obtain layers of homogeneous thickness and Co₃O₄ concentration. The volume fraction of Co₃O₄ particles in the deposit α reaches a limiting value of ca. 0.1 when the volume fraction of particles in suspension C exceeds 0.008. The current density j has little effect on α as long as it is in the range 1 to 20 mA cm⁻²; if j increases further, α decreases.PbO₂ + Co₃O₄ composite layers have been studied as electrode materials for the oxygen evolution reaction (mainly in NaOH solution). The overpotential and Tafel slope decrease upon increasing α. At a fixed potential, j is roughly proportional to OH⁻ concentration. The PbO₂ + Co₃O₄ electrode performance is fairly stable at 25°C but declines with time at higher temperature.     

氮掺杂碳纳米管负载Co3O4氧还原电催化剂的制备与性能

以碳纳米管(CNT)为原料,通过负载维生素B₁₂,简单热解得到了一种氮掺杂碳纳米管(N/CNT)负载低含量Co₃O₄纳米颗粒的氧还原电催化剂(Co₃O₄@N/CNT)。得益于均匀分散的Co₃O₄纳米颗粒以及氮掺杂,Co₃O₄@N/CNT表现出了优异的氧还原催化性能,其半波电位达到了0.844 V(vs RHE),超越了商业Pt/C(0.820 V(vs RHE))。与Pt/C相比,基于Co₃O₄@N/CNT组装的锌-空气电池表现出了更优的放电性能和循环稳定性。     

Co3O4空心球的简易合成及其电化学性能

通过简易的水热法"一锅"制备了Co3O4空心球。借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和傅里叶变换红外光谱法(FTIR)等对Co3O4的结构和形貌进行了表征。结果表明,产物由Co3O4纳米粒子构成,并形成明显的空心多孔结构。循环伏安法(CV)测试表明,所制得的Co3O4空心球呈现良好的电化学性能。本文同时对Co3O4空心球结构的形成过程和可能的机理进行了分析和讨论。     

聚多巴胺功能化的四氧化三钴纳米复合材料的制备及电催化性能

通过简单的自聚合反应在四氧化三钴表面包覆聚多巴胺膜,联合使用纳米铂和辣根过氧化物酶用于电催化还原过氧化氢。结果表明,聚多巴胺的使用增强后续纳米铂的负载量和辣根过氧化物酶的生物活性;四氧化三钴、纳米铂和辣根过氧化物酶的多重信号放大作用,大大增强了该复合材料的催化活性,提高了过氧化氢传感器的灵敏度。优化实验条件下,传感器对过氧化氢的检测范围为0.1～700μmol·L^-1,检测限为0.08μmol·L^-1。     

Catalytic decomposition of H2O2 on Co3O4 doped with MgO and V2O5

The effects of doping of Co₃O₄with MgO (0.4–6 mol%) and V₂O₅ (0.20–0.75 mol%) on its surface and catalytic properties were investigated using nitrogen adsorption at −196°C and decomposition of H₂O₂ at 30–50°C. Pure and doped samples were prepared by thermal decomposition in air at 500–900°C, of pure basic cobalt carbonate and basic carbonate treated with different proportions of magnesium nitrate and ammonium vanadate. The results revealed that, V₂O₅ doping followed by precalcination at 500–900°C did not much modify the specific surface area of the treated Co₃O₄ solid. Treatment of Co₃O₄ with MgO at 500–900°C resulted in a significant increase in the specific surface area of cobaltic oxide. The catalytic activity in H₂O₂ decomposition, of Co₃O₄ was found to suffer a considerable increase by treatment with MgO. The maximum increase in the catalytic reaction rate constant (k) measured at 40°C on Co₃O₄ due to doping with 3 mol% MgO attained 218, 590 and 275% for the catalysts precalcined at 500, 700 and 900°C, respectively. V₂O₅-doping of Co₃O₄ brought about a significant progressive decrease in its catalytic activity. The maximum decrease in the reaction rate constant measured at 40°C over the 0.75 mol% V₂O₅-doped Co₃O₄ solid attained 68 and 93% for the catalyst samples precalcined at 500 and 900°C, respectively. The doping process did not modify the activation energy of the catalyzed reaction but much modified the concentration of catalytically active constituents without changing their energetic nature. MgO-doping increased the concentration of CO³⁺–CO²⁺ ion pairs and created Mg²⁺–CO³⁺ ion pairs increasing thus the number of active constituents involved in the catalytic decomposition of H₂O₂. V₂O₅-doping exerted an opposite effect via decreasing the number of CO³⁺–CO²⁺ ion pairs besides the possible formation of cobalt vanadate.     

聚多巴胺功能化的四氧化三钴纳米复合材料的制备及电催化性能

通过简单的自聚合反应在四氧化三钴表面包覆聚多巴胺膜,联合使用纳米铂和辣根过氧化物酶用于电催化还原过氧化氢。结果表明,聚多巴胺的使用增强后续纳米铂的负载量和辣根过氧化物酶的生物活性;四氧化三钴、纳米铂和辣根过氧化物酶的多重信号放大作用,大大增强了该复合材料的催化活性,提高了过氧化氢传感器的灵敏度。优化实验条件下,传感器对过氧化氢的检测范围为0.1~700 μmol·L^-1,检测限为0.08 μmol·L^-1。     

纳米Co3O4的制备、 表征及CO低温催化氧化

Various nanometer Co₃O₄ samples were prepared and the catalytic performance of CO oxidation were examined. It was found that the activities of the catalysts were greatly changed with variation of the preparation methods and pretreatment conditions. Among the samples tested, Co₃O₄ prepared by using dodecylbenzene sulfonic acid sodium salt(DBS) as the surfactant, calcined at 300 ℃ showed the highest activity and it was able to oxidize completely CO even at -78 ℃. Characterization of these samples by XRD and BET means showed that the catalytic acitivity increased with the decrease of the average particle size, suggests that the average particle size of nanometer Co₃O₄ samples is the main controlling factor of the catalytic activity.     

一锅法制备Co3O4/g-C3N4复合光催化剂及其光催化性能

以三聚氰胺和六水合氯化钴为原料,一锅法制备Co_3O_4负载的多孔石墨相氮化碳(Co_3O_4/g-C_3N_4)复合光催化材料。采用X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光光谱(PL)等手段对其结构和光学特性进行表征。以盐酸四环素(TC)为目标污染物,评价了不同负载量Co_3O_4/g-C_3N_4复合光催化剂的可见光催化性能。结果表明,所制备的Co_3O_4/g-C_3N_4复合光催化剂为多孔结构,其比表面积较大,并在可见光区域具有显著的吸收。利用原位生成的Co_3O_4纳米粒子在氮化碳表面形成异质结构,可有效转移光生载流子,降低光生电子-空穴的再结合率,从而提高光催化活性。并且存在最佳Co_3O_4复合量,当六水合氯化钴加入量为三聚氰胺的8%(w/w)时,所制备的复合光催化剂CoCN-8具有最佳的光催化性能。在可见光的照射下,60 min内可降解85%的TC,而同样条件下,纯g-C_3N_4仅降解23%的TC。