Preparation of Pt/CeO2/HCSs anode electrocatalysts for direct methanol fuel cells

Hollow carbon spheres (HCSs) were prepared through a simple hydrothermal method using silica particles and glucose as the template and carbon precursor, respectively. HCSs used as supports for platinum catalysts deposited with cerium oxide (CeO₂) were prepared for application as anode catalysts in direct methanol fuel cells. The composition and structure of the samples were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic properties of the as-prepared catalysts for methanol oxidation were investigated by cyclic voltammetry (CV). The Pt/CeO₂/HCSs catalyst heated at 550 °C for 1 h exhibited the best catalytic activity for methanol oxidation.     

Electrocatalytic properties of platinum on hard carbon spherules derived from deoiled asphalt for methanol oxidation

In the present contribution, hard carbon spherules (HCSs) were synthesized from a deoiled asphaltene and were used as supporting materials for platinum (Pt) electrocatalyts. Pt nanoparticles were well dispersed on the surface of HCSs by an impregnation–reduction method. The morphology and microstructure of the as-prepared Pt/HCSs composites were studied by means of X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) techniques. The electrocatalytic properties of the Pt/HCS electrode for methanol oxidation were investigated by cyclic voltammetry and high electrocatalytic activity was observed.     

Improved kinetics of methanol oxidation on Pt/hollow carbon sphere catalysts

Hollow carbon spheres (HCSs) have been prepared by combining the hydrothermal method and intermittent microwave heating (IMH) technique. The preparation factors affecting the performance of the HCSs are studied. The results show that Pt nanoparticles supported on HCSs (Pt/HCS), which were heated for 3 min in a microwave oven, give the best performance for methanol oxidation. The higher electrochemical active surface area of the Pt/HCS catalysts results in higher catalytic activity for methanol oxidation compared to that of the commercial Pt/C catalyst at the same Pt loadings. Higher exchange current density and lower reaction activation free energy are observed on Pt/HCS catalysts, indicating improved kinetics. It is recognized that the hollow structure of the Pt/HCS with open microspores and nanochannels is responsible for this higher catalytic activity for methanol oxidation.     

Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors

ABSTRACT: MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO20.33H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.     

维生素A醛的合成研究

研究维生素A醛的合成方法。以维生素A醇为原料,经过烯丙位氧化制得维生素A醛。通过对科林试剂及其衍生物、活性MnO2作为维生素A醇的烯丙位氧化剂进行研究,确定了活性MnO2作为制备维生素A醛的氧化剂。通过对活性MnO2制备方法的研究,开发了晶型为G型的活性MnO2。G型的活性MnO2用于维生素A醛的制备中,其氧化活性高,选择性好,制备的维生素A醛粗品含量达到80%以上,氧化收率达70%以上。产品通过精制,含量可达95%以上,精制收率达94%以上。     

低温固相反应法在纳米电极材料合成中的应用

介绍了低温固相合成技术的特点和优势，以及该技术在制备二次碱锰电池正极材料及其改性添加剂中的应用，纳米级MnO2正极材料以及由纳米改性添加剂修饰的MnO2正极材料在深度放电时具有更优越的性能。     

高孔率泡沫状MnO_2催化材料的制备及其催化性能

以泡沫海绵为基体材料,采用电镀的方法制备了高孔率泡沫状MnO_2催化材料,测定其孔隙率和比表面积,利用X射线光电子能谱和扫描电镜对MnO_x膜层的组成和形貌进行分析,并通过臭氧催化分解试验评价其催化性能。结果表明,泡沫状MnO_2催化材料具有超大的比表面积,约为29.6 m~2·m~(-3),孔隙率达95%以上,6片高孔率泡沫状MnO_2催化片对臭氧的催化率第9天后仍高达97.75%,具有良好的催化性能。     

Fenton+MnO_2+A/O组合工艺处理过氧化甲乙酮生产废水

利用Fenton+MnO_2+A/O组合工艺处理过氧化甲乙酮生产废水。在Fenton+MnO_2预处理阶段对影响废水COD去除率的主要因素进行了考察,得到反应的最佳条件:p H=2.7,30%H_2O_2投加量为0.1 L/L,FeSO_4·7H_2O投加量为5 g/L,MnO_2投加量为8 g/L,MnO_2氧化反应时间为45 min。废水经Fenton+MnO_2氧化预处理后可生化性由0.14提高到了0.25左右。废水经Fenton+MnO_2+A/O组合工艺处理后,出水COD稳定低于500 mg/L。     

熔盐法合成MnO2粉体及其超级电容性能

采用熔盐法在不同温度下制备了MnO2粉体.X射线衍射仪分析表明:粉体样品为α-MnO2和γ-MnO2晶混合物,反应温度越高样品的结晶程度越好.将MnO2粉体与石墨、乙炔黑、聚四氟乙烯、羧甲基纤维素按质量比为75:10:10:2:3进行混合,在10 MPa压力下压制成电极.在2 mol/L (NH4)2SO4溶液中,用三电极体系对MnO2电极样品进行电化学性能测试.结果表明:制备粉体的反应温度是影响MnO2粉体制备的电极的电化学性能的重要因素,反应温度为450 ℃的粉体制备的电极样品电容性能最好.循环伏安测试表明该样品在0～1.0 V电位窗口范围内具有较好的矩形特征;交流阻抗测试结果显示样品具有典型的电容阻抗特性,其等效串联电阻和电极反应电阻分别为0.064 Ω和2.825 Ω.在电流密度为2 mA/cm2,恒流充放电时测得其放电比容量可达246.46 F/g.     

碳纳米管负载纳米MnO2复合材料对Pb2+吸附的研究

采用液相氧化还原法制备MnO2/MWNTs复合材料,通过SEM(扫描电子显微镜)观察MnO2在MWNTs表面的负载情况,XRD(X射线衍射仪)显示MnO2是以无定形态排列在MWNTs表面。吸附过程的前10分钟达到平衡吸附量的70%,80min达到吸附平衡,温度升高有益于吸附,pH值对吸附影响很大,吸附量随着pH值的上升而增加,对Pb2+脱除率甚至达到了95.31%。     

MnO2/MWNTs纳米材料的制备及对Cu（Ⅱ）吸附的研究

采用液相氧化还原法制二氧化锰/多壁碳纳米管(MnO2/MWNTs)复合材料,通过扫描电子显微镜(SEM)观察MnO2在MWNTs表面的负载情况,X射线衍射仪(XRD)显示MnO2是以无定形态排列在MWNTs表面。MnO2/MWNTs相比于MWNTs对Cu(Ⅱ)吸附能力提高了100%,MnO2最优负载量为30%,吸附过程的前10 min达到平衡吸附量的70%,80 min达到吸附平衡。温度升高有益于吸附。pH对吸附影响很大,吸附量随着pH的上升而增加,对Cu(Ⅱ)脱除率甚至达到了95.31%。     

MnO/MnO2对磷酸盐低熔玻璃性能的影响

;制备了含锰ZnO-Sb2O3-P2O5系统无铅低熔玻璃,其组成的配比(摩尔分数)为40.7%P2O5·36%ZNO-10%Sb2O3·2%Li2O·4%Na2O·3.3?O·4?O.借助红外光谱及差热分析考察了0～8%(摩尔分数)MaO及MaO2替代ZnO后对玻璃耐水性和低熔性的影响,借助紫外-可见光谱分析了锰离子在玻璃中的价态.结果表明:MaO/MnO2的引入改善了玻璃的耐水性,且以MaO2的作用更为显著;此外,锰的引入未明显提高玻璃的转变温度和软化温度,对密度及膨胀系数的影响也很小.玻璃中锰离子的价态主要与其在原料中的价态一致,同时存在有少量的Mn3 .在制备磷酸盐低熔玻璃时,MnO2是非常具有实用价值的一种组分.     

二氧化锰晶型对吡哆醇氧化反应的稳定性研究

以吡哆醇（1）为起始原料,经二氧化锰选择性氧化反应制得吡哆醛（2）,通过X射线衍射脚）分析不同市售二氧化锰的晶型,研究不同晶型对催化氧化能力的影响,发现较优的晶型为γα-MnO2（混铆。     

乙醇超临界干燥制备二氧化锰超细粉体

以MnCl2和NaOH为原料,利用超临界流体干燥技术(SCFD)制备了MnO2超细粉 体,采用X-射线衍射、粒度分析和扫描电镜确定了粒子的形貌和粒径,结果表明,采用超临界流 体干燥技术可以制备出颗粒细、大小均匀的纳米粒子。     

MnO2/MCNTs的制备及电容性能的研究

利用酸处理使多壁碳纳米管(MCNTs)表面功能化,继而结合原位化学液相沉淀法,成功制备了MnO2/MCNTs二元复合材料,并采用XRD、FTIR、SEM和TEM研究了材料的晶体结构和表面形态,运用循环伏安和交流阻抗方法研究其电化学性能.结果表明:MnO2/MCNTs二元复合材料的电容性能优于纯MnO2,且不同的MCNTs管径及长度对MnO2/MCNTs二元复合材料电化学性能及表面有影响.     

超临界流体干燥技术制备纳米二氧化锰

采用溶胶法和超临界流体干燥技术，在533K，7．6MPa的条件下，用超临界乙醇作为干燥剂制备纳米级二氧化锰，采用X射线衍射，透射电镜确定了二氧化锰粒子的行貌和粒径，结果表明，用超临界流体干燥技术可以得到颗粒细，大小均匀，抗团聚非常好的纳米粒子。     

MnO_2对APP-PER-MA膨胀阻燃体系热解过程的协同作用

从热重分析、热解活化能以及红外光谱等几个方面研究了氧化锰(MnO2)对以聚磷酸铵(APP)为酸源,季戊四醇(PER)为炭源,蜜胺为气源的经典膨胀型阻燃剂(IFR)热分解性能的影响。从傅立叶红外光谱的角度看,300~400℃时MnO2的存在加快了体系的分解和无机酸的生成速度,改变了IFR热解发生的时间,但是并没有从根本上改变热解过程。从表观活化能的角度看MnO2的添加提高了IFR阻燃剂第一、二阶段的热解活化能,降低了第三、四阶段的热解活化能。热重分析显示MnO2对IFR分解最后阶段残留量影响最大。     

纳米MnO_2的制备及其在废水处理中的应用

简述了MnO2晶体的基本形态特征,综述了目前纳米MnO2常用的合成方法,介绍了国内外对MnO2在废水处理中研究与应用现状,分析了当前研究中存在的问题与对策,并对MnO2的应用前景进行了展望。     

新生MnO2对甲基红的吸附性能研究

以MnSO4和KMnO4为主要原料制备出新生MnO2,并用新生MnO2对甲基红废水进行吸附实验,研究了甲基红废水的pH值、新生MnO2的用量和吸附时间等因素对吸附性能的影响。实验结果表明,在室温条件下,当溶液中甲基红质量浓度为100 mg/L、处理量为100 mL、pH值为4、吸附3 h、新生MnO2用量为40 mg时,甲基红的脱色率可达98.2%。     

氯酸镁氧化Mn~(2+)沉积法制化学MnO_2及其特性研究

在一定条件下，以氯酸镁氧化Ｍｎ２＋沉积法制化学ＭｎＯ２（简称（ＣＭＤ），对其进行ＭｎＯ２含量、视密度、肼指数、放电性能以及红外与差热等分析。结果表明，制得的ＣＭＤ电化活性较高，有望替代电解ＭｎＯ２（简称ＥＭＤ）作为干电池的阴极活性材料。