A periodic DFT study on adsorption of small molecules(CH4,CO,H2O,H2S,NH3)on the WO3(001) surface-supported Au

Gas molecules(such as CH4,CO,H2O,H2S,NH_3)adsorption on the pure and Au-doped WO3(001)surface have been studied by Density functional theory calculations with generalized gradient approximation.Based on the the calculation of adsorption energy,we found the most stable adsorption site for gas molecules by comparing the adsorption energies of different gas molecules on the WO3(001)surface.We have also compared the adsorption energy of five different gas molecules on the WO3(001)surface,our calculation results show that when the five kinds of gases are adsorbed on the pure WO3(001)surface,the order of the surface adsorption energy is CO>H2S>CH4>H2O>NH3.And the results show that NH3 is the most easily adsorbed gas among the other four gases adsorbed on the surface of pure WO3(001)surface.We also calculated the five different gases on the Au-doped WO3(001)surface.The order of adsorption energy was found to be different from the previous calculation:CO>CH4>H2S>H2O>NH3.These results provide a new route for the potential applications of Au-doped WO3 in gas molecules adsorption.     

基于Matlab GUI的微观化学反应过程可视化设计

Based on the quasi-classical trajectory (QCT) method and Matlab GUI technology, we developed a program code for visualizing the collision process of the elementary chemical reactions of the a + bc type. The general methodology of QCT, abstraction of dynamical properties of molecular collisions and the making of Graphical User Interface are introduced. The running results of an application to the reaction F + HCl→HF + Cl is also presented. The results showed that this program could vividly demonstrate the behavior and final state of the atom-diatom collision process in animated form. Students can interact with internal MATLAB code through graphical user interface, observe the reactive behavior and final results in real-time from multiple angles, which helps students to understand the complex reaction mechanism and deepen their perceptual impression of the chemical process at a microscopic atomic/molecular level.     

仿生叠层构型石墨烯对铝基复合材料的纳米摩擦性能的影响

利用纳米压痕和纳米划痕试验表征了仿生叠层构型铝基石墨烯复合材料(Bio-inspired laminated graphene reinforced aluminum martrix composite, BAMC)与纯铝的力学性能和摩擦磨损性能. 鉴于摩擦力由黏着作用和犁沟作用两分量共同组成,对比探究了BAMC与纯铝在微观摩擦磨损过程中的弹塑性转变过程,分析了黏着作用与犁沟作用在摩擦力中的贡献度,揭示了其微观摩擦磨损机制. 结果表明:相较于纯铝,BAMC的纳米硬度提高了约24%,总摩擦系数(Friction coefficient)降低了约28%,黏着作用分量和犁沟作用分量分别降低了32%和16%. 换言之,复合材料中的异质界面产生异质变形诱导强化,进而增强了应变硬化,使仿生叠层石墨烯铝基复合材料的硬度得到明显提升,并且仿生叠层构型的石墨烯主要通过降低黏着作用来实现减磨. 从微纳米尺度揭示了BAMC的力学性能和摩擦磨损性能显著提升的机理,可为提升其摩擦磨损性能提供理论依据. 目前的工作通过纳米划痕和纳米压痕强调了叠层结构石墨烯的添加对块体复合材料的摩擦性能的影响,并表明仿生叠层构型铝基石墨烯是搭建仿生叠层结构的小尺寸理想增强体.      

Influence of substrate temperature on surface textured ZnO:Al films etched with NaOH solution

Transparent conducting Al-doped ZnO (ZnO:Al, AZO) thin films with good optical and electrical characteristics were prepared by direct current pulse magnetron sputtering. Textured surfaces of AZO films were obtained by etching with NaOH solution successfully and the effect of substrate temperature on the surface texture was investigated. The surface is covered with craters after etching with 5% NaOH solution, and the crater diameter decreases gradually as substrate temperature increases. For AZO film deposited at 270, the crater diameters is 0.5-1 μm, which is an effective surface texture for light trapping.     

O2流量对磁控溅射N掺杂TiO2薄膜成分及晶体结构的影响

利用直流脉冲磁控溅射方法在室温下通过改变O₂流量制备具有不同晶体结构的N掺杂TiO₂薄膜,利用台阶仪、X射线光电子能谱仪、X射线衍射仪、紫外-可见分光光度计等设备对薄膜沉积速率、化学成分、晶体结构、禁带宽度等进行分析.结果表明:所制备的薄膜元素配比约为TiO_1.68±0.06N_0.11±0.01,N为替位掺杂,所有样品退火前后均未形成Ti—N相结构,N掺杂TiO₂薄膜的沉积速率、晶体结构等主要依赖于O₂流量.在O₂流量为2 sccm时,N掺杂TiO₂薄膜沉积速率相对较高,薄膜为非晶态结构,但薄膜内含有锐钛矿(anatase)和金红石(rutile)相晶核,退火后薄膜呈anatase和rutile相混合结构,禁带宽度仅为2.86 eV.随着O₂流量的增加,薄膜沉积速率单调下降,退火后样品禁带宽度逐渐增加.当O₂流量为12 sccm时,薄膜为anatase相择优生长,退火后呈anatase相结构,禁带宽度为3.2 eV.综合本实验的分析结果,要在室温条件下制备晶态N掺杂TiO₂薄膜,需在高O₂流量(＞10 sccn)条件下制备. 关键词： 2薄膜')" href="#">N掺杂TiO₂薄膜 磁控溅射 化学配比 晶体结构     

电解质浓度和温度对活性炭电容性能的影响

采用循环伏安、交流阻抗和恒流充放电技术考察了电解质浓度和温度对活性炭电容性能的影响. 活性炭电容器在0.1、0.5、1.0和6.0 mol·L^-1 KOH溶液中性能测试结果表明: 活性炭在高浓度电解质中具有高电容和低内阻, 但电位窗口较窄; 电容和内阻与KOH浓度的对数成正比. 活性炭电容在不同温度(20、40、80 °C)的性能测试结果表明: 高温能够增加电容和降低内阻, 但是却加速了长期充放电过程中电容的衰减.     

基于纳米SnO2材料的二维纳米催化发光传感器研制及其测定甲基叔丁基醚的应用

以碳纳米管(CNT)为模板,采用液相沉积法可控合成了SnO2-CNT复合纳米材料、SnO2纳米棒两种形貌的SnO2纳米材料,研究了它们对甲醇、MTBE催化发光的影响.通过考察两种不同形貌SnO2纳米材料的结构、比表面积与其催化发光的关系,建立了一种二维纳米催化发光传感器,并测定了MTBE产品的纯度和其中的甲醇含量,甲醇...     

准经典轨线研究Li+HF(ν=0, j=0)→LiF+H反应动力学

基于Aguado等人拟合的APW势能面(PES), 运用准经典轨线(QCT)方法, 对反应Li+HF(ν=0, j=0)→LiF+H的动力学性质进行了计算. 主要研究了不同碰撞能条件下的反应截面、转动取向、产物散射角分布和竞争反应模式等. 结果表明, 该反应存在直接提取型和间接插入型两种反应模式, 在低能量下反应以间接插入反应模式为主, 能量大于200 meV时则以直接提取反应为主.     

The study on the dynamic response performance of PEMFC with electrodeposited RuO_2·xH_2O-Pt/C electrode

Dynamic response performance of proton exchange membrane (PEM) fuel cells affects its durability and reliability significantly. In this study, electrodeposited RuO2 xH2O-Pt/C was prepared to promote the PEM fuel cell dynamic response performance. The prepared RuO2 xH2O-Pt/C was characterized by scanning electron microscopy (SEM) equipped with energy disperse spectroscopy (EDS), which shows that RuO2 xH2O was electrodeposited on the surface of Pt/C. Performance of single cells with and without RuO2 xH2O-Pt/C at the cathode under a certain operating condition was studied using cyclic voltammetry, electrochemical impedance spectra (EIS) and polarization curve techniques. When the fuel cell modified with RuO2 xH2O-Pt/C was operated at lower pressure, a faster and more stable dynamic response could be found. Modifying with RuO2 xH2O-Pt/C composite material not only slightly increases the single cell performance but also dramatically improves the dynamic response performance, revealing that RuO2 xH2O-Pt/C can buffer the voltage undershoot whenever the current increases instantly.     

铜-石墨材料摩擦学行为的研究

采用粉末冶金技术制备了铜-石墨烧结材料,通过定速摩擦试验机,研究了石墨含量与第三体形态的关系及对材料摩擦性能的影响.结果表明:石墨含量小于15%时,石墨对材料的孔隙度及摩擦温度影响明显,表现出材料的摩擦磨损性能与石墨含量密切相关,这归因于干摩擦条件下摩擦表面形成的含有石墨粒子的第三体对摩擦性能作用明显.石墨含量低,形成的第三体金属成分高,硬质金属的犁沟作用导致摩擦系数和磨损率较高.随石墨含量增加,第三体中的石墨含量增加,这导致第三体致密程度和黏着程度降低,松散易流动的第三体有利于降低犁沟程度,从而起到降低和稳定摩擦系数、减少磨损率的作用.