高性能Pt纳米管中管电催化剂在甲醇燃料电池中的应用

通过ZnO模板辅助的电沉积方法设计和合成了Pt管中管阵列.作为一种具有利用率高、活性物质传输快的三维结构的电催化剂,Pt管中管阵列显示了高电化学活性面积（64.9 m²/gPt）.与Pt纳米管和商业Pt/C催化剂相比,Pt管中管阵列明显提高了甲醇氧化电催化活性和稳定性.另外,Pt管中管阵列也显示了优越的抗CO毒化能力.这个研究展示了高性能Pt基直接甲醇燃料电池电催化的一个重要进展.     

Pt-TiO2/Graphene催化剂的氧还原和甲醇氧化电催化性能研究

以二(2-羟基丙酸)二氢氧化二铵合钛（TBA）和氧化石墨烯（GO）为前驱体,通过水热法合成出不同TiO₂含量的TiO₂/Graphene（TiO2/G）复合材料,随之用微波醇热法还原Pt前驱体可得Pt-TiO₂/G催化剂. 实验结果表明,TiO₂可与Pt相互作用,添入适量TiO₂的Pt-TiO₂/G催化剂具有较高的氧还原电催化活性及甲醇氧化的电催化活性与稳定性. 但TiO₂电导率偏低,过量TiO₂的添入反而使其电催化性能降低.     

甲醇在不同结构氧化钨-Pt/C催化剂上的电催化氧化行为

采用水热法合成2种氧化钨（WO3）纳米材料,并利用XRD和电子探针显微分析仪（EPMA）进行了表征。 利用循环伏安法研究了Pt-WO3/C电极对甲醇氧化的电催化活性。 结果表明,Pt-WO3/C催化剂对甲醇氧化的电催化活性优于Pt/C催化剂,且氧化钨质量分数为20%的Pt-氧化钨/C催化效果最好。 与青铜相氧化钨掺杂的Pt/C电极比较,掺杂焦绿石型氧化钨的Pt/C电极催化性能有很大提高,这是由于焦绿石型氧化钨表面具有较多OHads。 质量分数20%的Pt-焦绿石型氧化钨/C在0.5 mol/L CH3OH+1 mol/L H2SO4溶液中对甲醇氧化的峰电流密度达到87.2×10-3 A/cm2。     

Eu掺杂的ZnO/MIL-53(Fe)光催化剂的合成及其对醇类选择性氧化的催化性能研究

采用原位合成法将稀土元素Eu掺杂到半导体ZnO中,并与MIL-53（Fe）复合,成功制备了三维（3D）纳米复合光催化剂Eu-ZnO/MIL-53（Fe）,通过X射线衍射（XRD）、红外（FT-IR）、扫描电子显微镜（SEM）、紫外可见漫反射光谱（UV-Vis DRS）、光致发光光谱（PL）、X射线光电子能谱分析（XPS）及电化学阻抗谱（EIS）等手段对复合材料的结构、形貌以及光学电学性能进行了详细的表征.实验结果表明：引入稀土元素可以极大地提高MIL-53（Fe）的光催化效率,同时促进光生电子-空穴的有效分离,使得催化活性进一步提高.通过活性捕捉实验和电化学手段对该反应可能的反应机理进行探究,结果表明：该光催化过程是通过空穴（h⁺）和羟基自由基（·OH）共同作用实现苯甲醇的选择性氧化.通过循环实验和表征参加光反应前后的催化剂的结构来探究该催化剂的光稳定性和热稳定性,结果表明该复合型光催化剂具有良好的光稳定性和热稳定性.     

新型的钛基Ni-Sn/Ti电极的制备及对甲醇氧化反应的电催化活性

利用电热法,一步制备出新型的钛基Ni-Sn/Ti电极(Ni8Sn/Ti, Ni7Sn3/Ti 和 Ni/Ti)。扫描电镜（SEM）图像表明,催化剂以片状的纳米颗粒形式沉积于钛基体上。利用电化学伏安技术、电位阶跃法和电化学交流阻抗谱（EIS）,研究了这些电极在1mol.L�1NaOH溶液中对甲醇氧化反应的电催化活性。研究表明,与Ni7Sn3/Ti,Ni/Ti以及多晶镍电极相比,Ni8Sn/Ti电极对甲醇氧化反应表现出更高的阳极氧化电流和更低的起始电位。EIS分析表明,在本文所考察的阳极电位和甲醇浓度下,Ni8Sn/Ti电极对甲醇氧化反应显示出极低的电荷传递电阻。结果表明,这种新型的钛基Ni8Sn/Ti电极对甲醇氧化反应具有极高的电催化活性。     

嵌段共聚物模板法一步制备WC/C基底电极材料

以酚醛树脂作为碳源,采用嵌段共聚物模板法一步制备新型有序介孔碳化钨/碳（WC/C）纳米颗粒. WC/C颗粒的比表面积为414 m²·g^-1,表面的平均孔径约为38 nm,处于介孔范围内（2 ~ 50 nm）. 通过调节树脂预聚时间以及碳化温度等条件制备出结构形貌较优的WC/C复合材料,并探讨了材料形成机理. 使用X射线衍射、扫描电镜、透射电镜及氮气吸脱附等方法表征了复合材料的结构. 将贵金属铂负载于WC/C表面制备得新电催化材料Pt-WC/C,使用循环伏安法和计时电流法对Pt-WC/C复合材料的电化学性能进行检测,并与商用碳载铂（Pt/C）材料进行对比. 测试结果发现,Pt-WC/C对甲醇的电催化活性以及稳定性等方面都表现出优于商用Pt/C材料的活性,这主要归功于碳化钨高度分散于碳表面.     

一步法绿色合成甲醇燃料电池阳极催化剂

以含有多羟基的聚乙二醇为还原剂,采用水热还原技术一步法制备出Pt/石墨烯复合物电极材料。采用扫描电子显微镜(SEM)技术对石墨烯和Pt/石墨烯材料进行了形貌和结构表征。利用循环伏安电化学测试技术研究了该Pt/石墨烯电极对甲醇燃料小分子的电催化氧化性能。研究结果表明该复合材料作为阳极催化剂对甲醇表现出优异的电催化活性。该电极材料有望用作甲醇燃料电池的阳极催化剂材料。     

Pt微粒修饰纳米纤维聚苯胺电极对甲醇氧化电催化

以脉冲电流法制备的纳米纤维状聚苯胺(PANI)为Pt催化剂载体，用它制备了甲醇阳极氧化的催化电极Pt/（nano-fibular PANI）.研究结果表明, Pt/（nano-fibular PANI）电极对甲醇氧化具有很好的电催化活性,并有协同催化作用.在相同的Pt载量条件下， Pt/（nano-fibular PANI）电极比Pt微粒修饰的颗粒状聚苯胺电极Pt/(granular PANI)具有更好的电催化活性.此外， Pt的电沉积修饰方法同样影响Pt/（nano-fibular PANI）电极对甲醇氧化的催化活性.脉冲电流法沉积Pt形成的复合电极较循环伏安法电沉积得到的Pt复合电极具有更优异的催化活性.     

Pt纳米空球粒径的可控制备及其甲醇电催化氧化

利用表面活性剂十二烷基磺酸钠（SDSN）的调控合成不同粒径的硒模板和铂纳米空球（Pthollow）,并将其修饰于玻碳（GC）基底即可制得Pthollow/GC电极;采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）和X射线光电子能谱等观察表征了Pthollow样品的形貌与组成;以甲醇为探针分子,研究Pthollow/GC和电沉积铂电极（Ptnano/GC）对甲醇氧化的电催化活性. 结果表明,由铂原子簇团构筑的多孔铂纳米空球粒径均匀,分散性好;用4 μmol·L^-1 SDSN控制合成的直径为130 nm的Pthollow制备的Pthollow/GC电极对甲醇氧化的电催化活性最佳.     

Au-Pt催化剂的控制合成及其对乙醇电氧化性能

乙醇电氧化（EOR）是直接乙醇燃料电池和电解乙醇制氢共有的阳极反应.Au@Pt核壳和AuPt合金是广泛使用的两种电催化材料,迄今尚无两者对EOR性能的对比研究.以CO作为还原剂和淬灭剂合成了近似Pt单层的Au@Pt/C催化剂,作为对照,以NaBH₄还原法合成了相同Au∶Pt物质的量比和金属载量的AuPt/C催化剂;运用透射电子显微镜（TEM）、扫描透射电子显微镜-能谱仪（STEM-EDS）、X射线粉末衍射（XRD）和X射线光电子能谱（XPS）等手段综合表征了两者结构之差异,同时以电化学循环伏安法和计时电流法测试了在碱性体系中其对EOR的电催化性能.结果表明,相比于商业化的Pt/C和Au/C,Au@Pt/C和AuPt/C对EOR的活性和稳定性均有着显著提升;Au@Pt/C对EOR的电催化活性和对C-C键断裂能力略优于AuPt/C.双金属催化剂中Au与Pt之间的晶格应力和部分电荷转移等效应可能是其性能提升的主要原因.     

A comparative study of the electrooxidation of C1 to C3 aliphatic alcohols on Ni modified graphite electrode

Nickel modified graphite electrodes(G/Ni) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol,ethanol,1-propanol and 2-propanol in alkaline solutions.The methods of cyclic voltammetry(CV),chronoamperometry(CA) and impedance spectroscopy(EIS) were employed.In CV studies,the electrochemical response,peak current varied in the order of MeOH > EtOH > 1-PrOH > 2-PrOH.Under the CA regime,a higher catalytic rate constant obtained for methanol oxidation was in agreement with CV measurements.Lower charge transfer resistance was obtained for low carbon alcohols oxidation and significantly higher exchange current density was obtained for methanol oxidation.     

氧化锌分散体光反应产生的自由基中间体

溶液中光诱导的电子转移反应已进行了大量的研究。而半导体粉末在水相或非水溶剂中的光化学研究也与自俱增^[1-3]。这种光化学与成像体系、太阳能转换以及光催化或污物的光降解有关。因此,越来越引起人们的重视。     

Oxidation of Methanol and Other Low-Molecular-Weight Alcohols on the RuNi Catalysts in an Alkaline Environment

The results of investigations of the RuNi catalysts, which are designed for the electrooxidation of methanol and other low-molecular-weight alcohols in alkaline solutions, are presented. It is shown that the maximum catalytic activity in this reaction is exhibited by a catalyst, which was synthesized thermochemically on acetylene black AD100 containing 15 wt % RuNi at a 68 : 32 atomic ratio (in at. %) between the metals. The structure of the synthesized catalysts is studied by the methods of x-ray photoelectron spectroscopy and x-ray diffraction analysis (XRDA). The area of the metal surface is determined on the basis of the magnitude of the adsorption of CO from the voltammetric curves. An analysis of the data obtained in this work leads to the conclusion that ruthenium in the composition of the catalyst exists in metallic and partially oxidized states and nickel exists in the form of a nonstoichiometric oxide. In addition it is found that the insertion of nickel into the system leads, as follows from the XRDA data, to the dispersion of ruthenium and, as follows from the voltammetric curves, to a decrease in the specific surface area accessible to the adsorption of CO. This is probably connected with the decoration and blockade of a portion of the ruthenium surface by some nickel oxides. Data on the influence, which is exerted by the concentration of methanol, alkali, and temperature on the electrocatalytic activity of the AD100 + 15 wt % RuNi catalyst at a 68 : 32 atomic ratio (in at. %) between the components, are presented. Rates of the oxidation of methanol, ethanol, n-butanol, and ethylene glycol in identical conditions on the catalyst AD100 + 15 wt % RuNi (68 : 32 at. %) between the metals are compared with one another. The oxidation currents, which are observed at a potential of 0.3 V, are equal to 5.48, 2.67, 0.48, and 0.47 A per gram of the catalyst for ethanol, ethylene glycol, methanol, and n-butanol, respectively.__________Translated from Elektrokhimiya, Vol. 41, No. 7, 2005, pp. 829–839.Original Russian Text Copyright © 2005 by Tarasevich, Karichev, Bogdanovskaya, Kapustin, Lubnin, Osina.     

Gas sensing performance of polyaniline/ZnO organic-inorganic hybrids for detecting VOCs at low temperature

Polyaniline (PANI) was prepared by the chemical oxidative polymerization of aniline, and ZnO, with the mean particle size of 28 nm, was synthesized by a non-aqueous solvent method. The organic-inorganic PANI/ZnO hybrids with different mass fractions of PANI were obtained by mechanically mixing the prepared PANI and ZnO. The gas sensing properties of PANI/ZnO hybrids to different volatile organic compounds (VOCs) including methanol, ethanol and acetone were investigated at a low operating temperature of 90°C. Compared with the pure PANI and ZnO, the PANI/ZnO hybrids presented much higher response to VOCs. Meanwhile, the PANI/ZnO hybrid exhibited a good reversibility and a short response-recovery time, implying its potential application for gas sensors. The sensing mechanism was suggested to be related to the existence of p-n heterojunctions in the PANI/ZnO hybrids.     

Bifunctionality of Cu/ZnO catalysts for alcohol-assisted low-temperature methanol synthesis from syngas:Effect of copper content

Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO_X catalysts while varying the copper content(X). Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content(X) strongly affected the catalytic activity of the Cu/ZnO_X catalysts, and accordingly, the Cu/ZnO_0.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.     

Higher-alcohols biorefinery

The concept of a biorefinery for higher-alcohol production is to integrate ethanol and methanol formation via fermentation and biomass gasification, respectively, with, conversion of these simple alcohol intermediates into higher alcohols via the Guerbet reaction. 1-Butanol results from the selfcondensation of ethanol in this multistep reaction occurring on a single catalytic bed. Combining methanol with ethanol gives a mixture of propanol, isobutanol, and 2-methyl-1-butanol. All of these higher alcohols are usefulas solvents, chemical intermediates, and fuel additives and, consequently, have higher market values than the simple alcohol intermediates. Several new catalysts for the condensation of ethanol and alcohol mixtures to higher alcohols were designed and tested under a variety of conditions. Reactions of methanol ethanol mixtures gave as high as 100% conversion of the ethanol to form high yields of isobutanol with smaller amounts of 1-propanol, the amounts in the mixture depending on the starting mixture. The most successful catalysts are multifunctional with basic and hydrogen transfer components.     

Micellisation thermodynamics of sodium lauroylsarcosinate in water–alcohol binary mixtures

Aggregation of sodium lauroylsarcosinate (SLS) in aqueous solutions of methanol, ethanol, propanol and ethylene glycol at 288–313 K has been determined from conductivity measurement in the range 0–20% v/v of additives. The precise values of the critical micelle concentration (CMC) and the degree of counter-ion dissociation of micelles were obtained at each temperature by fitting the specific conductivity-surfactant concentration curve to the integrated form of the Boltzmann-sigmoid equation. The CMC was found to increase with increase in additive concentrations in the case of methanol and ethylene glycol, while it decreases with increase in ethanol and propanol concentration. The equilibrium model of micelle formation was applied to obtain the thermodynamic parameters of micellisation. The Gibbs free energies were observed to vary only slightly with temperature and additive concentrations. Enthalpy–entropy compensation was observed for all the systems with a constant compensation temperature of ≈300 K and negative compensation enthalpy.     

Preparation and characterization of nano-sized Pt-Ru/C catalysts and their superior catalytic activities for methanol and ethanol oxidation

Carbon-supported PtRu nanoparticles (Ru/Pt: 0.25) were prepared by three different methods; simultaneous reduction of PtCl(4) and RuCl(3) (catalyst I) and changing the reduction order of PtCl(4) and RuCl(3) (catalysts II and III) to enhance the performance of the anodic catalysts for methanol and ethanol oxidation. Structure, microstructure and surface characterizations of all the catalysts were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the XRD analysis showed that all catalysts had a face-centered cubic (fcc) structure with different and smaller lattice parameters than that of pure platinum, showing that the Ru incorporates into the Pt fcc structure by different ratios in all the catalysts. The typical particle sizes of all catalysts were in the range of 2-3 nm. The most active and stable catalyst for methanol and ethanol oxidation is catalyst III, in which a large amount (more than 90%) of PtRu alloy formation was observed. It has been found that this catalyst is about 8.0 and 33.4 times more active at ～0.60 V towards the methanol and ethanol oxidation reactions, respectively, compared to the commercial Pt catalyst.     

Selective synthesis of isobutanol by means of the Guerbet reaction: Part 2. Reaction of methanol/ethanol and methanol/ethanol/n-propanol mixtures over copper based/MeONa catalytic systems

The synthesis of isobutanol via the Guerbet condensation between methanol and ethanol was studied by using sodium methoxide (MeONa) as soluble basic component and copper-based catalysts as heterogeneous dehydrogenating/hydrogenating metal species. The effect of the nature of the catalyst and the relative amount of its individual components with respect to the reacting alcohols as well as of temperature on productivity and selectivity of the process was investigated. The collected data indicated that the copper chromite/MeONa was more active than Cu-Raney/MeONa system. The reaction was shown to proceed with the formation only of n-propanol and isobutanol. Ethanol conversion up to 61% with selectivity to isobutanol up to 98.4% was obtained. The same catalytic systems were also employed in the reaction of the methanol/ethanol/n-propanol ternary mixture. Again copper chromite/MeONa resulted more active than the Cu-Raney/MeONa system. Finally, experiments were carried out on methanol/n-propanol mixtures in the presence of the copper chromite/MeONa catalytic system by recycling both the recovered solid copper component and the liquid reaction mixture for evidencing eventual copper leaching by MeONa. On the basis of the obtained results it was concluded that in the Guerbet reaction copper chromite works as heterogeneous catalyst.     

An ethanol sensor based on cataluminescence on ZnO nanoparticles

A novel gas sensor for the determination of ethanol was proposed in the present work, which was based on the generated cataluminescence emission from catalytic oxidation of ethanol on the surface of ZnO nanoparticles. The cataluminescence characteristics and the effect of different parameters on the signal intensity, such as morphology of synthesized ZnO, temperature and flow rate, were discussed in detail. Under the optimized experimental conditions, the calibration curve of cataluminescence intensity versus ethanol vapor concentration was linear in the range 1.0-100 ppm, and with a detection limit of 0.7 ppm (S/N = 3). Compared with the traditional electrical conductivity-based ZnO gas sensor for the determination of ethanol, the proposed ethanol sensor showed the advantages of high sensitivity, high selectivity and low working temperature.