氮气流量对金刚石膜生长的影响研究

采用电子辅助化学气相沉积法(EA-CVD)制备掺氮金刚石薄膜,研究了不同氮气流量对金刚石膜的生长速率、表面形貌和膜品质的影响.实验发现,在较低的氮气流量下,金刚石膜的生长速率增加,在较高的氮气流量下生长速率减小.利用SEM、Raman光谱、XPS等测试手段对样品的表面形貌及品质进行了表征.结果表明,当氮气流量为4sccm时金刚石膜的结晶比较完整;当氮气流量为8sccm时生成与(100)面共存的"菜花状".氮气流量的进一步增加,"菜花"表面(100)晶面显露的数量明显降低,非金刚石碳含量和氮杂质含量增加,金刚石膜的品质明显下降.     

金刚石膜的氮掺杂行为

采用电子辅助化学气相沉积法(EA-CVD)制备了氮掺杂金刚石膜,用SEM、Raman光谱、XPS、EPR等测试手段研究了金刚石薄膜的品质和膜中的氮杂质状态。结果表明,随着氮气流量的增加,金刚石膜的形貌从完整的晶面逐渐变为与(100)面共存的“菜花状”,且非晶碳的含量增加,品质下降。金刚石膜中氮以Ns0、[N—V]0和[N—V]-1的形式存在,在较低氮气流量下[N—V]0和[N—V]-1的含量较多,Ns0氮杂质的质量分数在1.50×10-5～4.83×10-4之间变化。     

硼掺杂金刚石薄膜电极在酸碱盐中的电化学性质研究

通过热丝化学气相沉积技术,在P型单晶衬底上制备了掺硼金刚石薄膜电极。采用扫描电子显微镜和X射线衍射分析了丙酮流量对硼掺杂金刚石薄膜电极的表面形貌的影响,采用循环伏安法分析硼掺杂金刚石薄膜电极在不同浓度的酸碱盐电解液中的电化学特性。结果表明,硼掺杂金刚石薄膜质量随着丙酮流量的增加而先提高后下降的趋势,并且硼掺杂金刚石薄膜电极在不同电解质中存在不同的电化学窗口,中性溶液中的电化学窗口最宽在3.2 V以上,具有极强的电化学氧化性能。     

热丝化学气相沉积制备BDD薄膜电极的电催化特性

研究了热丝化学气相沉积法(HFCVD)制备得到掺硼金刚石膜电极电催化氧化典型有机物苯酚的特性.Raman光谱测试显示制备BDD电极具有较好的金刚石相,循环伏安测试表明该电极具有较高的析氧过电位(+2.3V vsSCE).在电催化氧化苯酚过程中,化学需氧量(COD)能够有效去除,降解过程中有较高的电流效率,在COD较高的情况下,瞬时电流效率(ICE)可达100%,随着COD的降低ICE逐渐减少.催化实验结果表明,BDD电极是一种优良的电催化降解有机物新型电极.     

富氮N_2/CH_4/H_2体系中金刚石纳米线的制备研究

使用微波等离子体化学气相沉积(MPCVD)法在富氮N_2/CH_4/H_2体系中纳米金刚石膜沉积进行研究。使用扫描电子显微镜对纳米金刚石膜的表面形貌进行测试,使用光射线光电子能谱(XPS)和拉曼光谱对纳米金刚石膜的表面化学结构进行表征。结果表明,氮气浓度的改变对纳米金刚石膜的表面形貌和晶粒尺寸都有明显影响。在氮气浓度为85%时,纳米金刚石膜的表面由平均长度为2.5μm金刚石纳米线组成,晶粒尺寸在85%最低,为8 nm。纳米金刚石膜氮元素含量随氮气浓度上升而上升在95%为2.68%。晶粒尺寸下降,晶界含量上升,C=C键含量上升;晶粒尺寸上升,晶界含量下降,C=C含量下降。C-C键含量随着晶粒尺寸下降而下降,随晶粒尺寸上升而上升,同时C-C峰的FWHM值在氮气浓度为85%时最低为1.16 e V。     

稀土铒改性钛基PbO2电极的制备和性能

采用电沉积法制备了稀土铒改性钛基PbO₂电极,用SEM、EDS和XRD技术分析了表面物相和结构,用EIS、线性极化扫描、荧光光谱分析和苯酚降解实验对其性能进行了表征。结果表明,稀土铒改性钛基PbO₂电极镀层的结构主要为β-PbO₂晶型,其晶粒明显细化,比表面积增大;电致生成羟基自由基的能力是未改性电极的2.3倍;改性电极具有更小的电化学反应电阻和更高的阳极析氧过电位。苯酚降解实验表明,稀土铒掺杂改性明显提高了钛基PbO₂电极的电催化性能,2h降解率达91.8%。     

CV和Tafel曲线对稀土掺杂Ti/SnO2-Sb电极电催化性能研究

采用热分解法制备了稀土Dy、Nd、Eu及Gd掺杂Ti/SnO2-Sb电极,以苯酚为目标有机物,研究了所制备电极降解有机物的性能.在500 mg/L苯酚溶液中进行了所制备电催化电极的循环伏安(CV)特性分析,研究发现4种稀土(Dy、Nd、Eu和Gd)掺杂电极中苯酚在Nd掺杂Ti/SnO2-Sb(Ti/SnO2-Sb-Nd)电极上的直接氧化的峰电流最高,为4.46 mA/cm2.在0.5 mol/L的H2SO4溶液中进行了Tafel曲线测试,4种稀土掺杂Ti/SnO2-Sb电极的析氧电位分别为2.293、2.313、2.277、2.263 V(vs.Ag/AgCl).结果表明,所制备的4种稀土掺杂电极降解苯酚的性能与采用CV和Tafel曲线方法分析的结果一致,可以采用电化学方法评价电极的电催化氧化性能.     

微波功率对掺氮纳米金刚石薄膜组成、结构及性能的影响

以CH4和CO2作生长金刚石薄膜的反应气体,以Ar作载气将三聚氰胺甲醇饱和溶液带入沉积室内作氮掺杂源,用微波等离子体化学气相沉积法在单晶硅衬底上制备出掺氮纳米金刚石薄膜。通过拉曼光谱、原子力显微镜、霍尔效应研究了掺氮纳米金刚石薄膜的组成、结构和导电性能,重点研究了微波输入功率对薄膜特性的影响。结果表明,制备的掺氮纳米金刚石薄膜具有良好的电子导电性,且随着激发等离子体微波功率的增大,其晶粒尺寸、晶界宽度、表面粗糙度和电导率增大,在最佳微波功率条件下制备出电子电导率高、材料质量好的纳米金刚石薄膜。     

金刚石膜电极的电化学研究

概述了电化学水处理方法、高硼掺杂金刚石膜电极的电化学研究.介绍了高硼掺杂金刚石膜电极的制备、金刚石膜电极在无机和有机废水处理方面的应用.实验表明金刚石膜电极对有代表性的污水具有明显的降解作用,可与其它处理方式结合.     

氮掺杂和SnO2纳米粒子负载对全固态对称型石墨烯超级电容器性能的影响

电极材料是影响超级电容器性能的主要因素。本研究采用溶剂热法合成石墨烯和氮掺杂石墨烯, 通过简单的化学法在其表面负载SnO₂纳米粒子。利用刮涂工艺在FTO玻璃表面制备石墨烯、SnO₂/石墨烯、氮掺杂石墨烯和SnO₂/氮掺杂石墨烯薄膜, 并经400℃热处理。分别以制备的石墨烯基薄膜和PVA/H₃PO₄为电极和电解质组装对称型全固态超级电容器。测试结果表明, 与石墨烯相比, 氮掺杂石墨烯具有较大的晶粒尺寸、较高的比表面积和较高的超电容性能; SnO₂纳米粒子负载可显著提高石墨烯和氮掺杂石墨烯的超电容性能。     

氮掺杂TiO_2中空复合微球的制备及可见光光催化性能

为了提高TiO2的可见光光催化性能,以微米级聚苯乙烯微球为模板,钛酸四丁酯为前驱体,三乙胺为氮源,采用静电吸附自组装法制备了粒径为1.20μm、壳层的厚度约为30nm且球形形貌良好的氮掺杂TiO2中空复合微球,采用SEM、XPS、XRD和紫外-可见分光光度计研究了其结构及光催化性能。结果表明:氮进入TiO2晶格内取代了部分O并改变了晶格中Ti和O的化学状态,但对TiO2晶型结构没有明显影响;氮掺杂后的TiO2中空复合微球禁带宽度变窄,氮掺杂TiO2中空复合微球不仅在紫外区有较强的光吸收能力,在可见光区也表现出较强的光响应性,对甲基橙的光催化降解率较Degussa P25型纳米TiO2的明显增强。研究结果对TiO2在光催化领域的应用具有理论指导意义。     

A STUDY ON THE THERMAL STABILITY TO 1000°C OF VARIOUS CARBON ALLOTROPES AND CARBONACEOUS MATTER BOTH UNDER NITROGEN AND IN AIR

The thermal behavior of graphite, C₆₀ fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA-DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C₆₀ and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed.

The combustion reaction in air flow of graphite, C₆₀ and C₇₀ fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA-DTA at a heating rate of 20°C/min. C₇₀ fullerene and fullerene black have been found to be the most reactive carbon materials with O₂. The role played by C₇₀ in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O₂ attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C₆₀ fullerene appears closer to that of graphite although it appears to be more reactive with O₂. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA-DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed.     

Morphological and electrochemical properties of boron-doped diamond films on carbon cloths with enhanced surface area

The electrochemical properties of doped diamond electrodes (10¹⁷–10¹⁹ B cm^− 3) grown on carbon fiber cloths in H₂SO₄ 0.1 mol L^− 1 electrolyte were investigated. Cyclic voltammograms of B-doped diamond/carbon fiber cloth and carbon fiber cloth electrodes showed that both kinds of electrodes possess similar working potential windows of about 2.0 V. The electrode capacitance was determined by impedance spectroscopy and chronopotentiometry measurements and very close values were obtained. The capacitance values of the diamond film on carbon fiber cloths were 180 times higher than the ones of diamond films on Si. In this paper we have also discussed the capacitance frequency dependence of diamond/carbon cloth electrodes.     

Ti掺杂MoS2薄膜的抗氧化性和电学性能

用磁控溅射在硅片上制备MoS₂和Ti-MoS₂薄膜,并将其在恒温恒湿箱中在AT 30℃、RH 70%条件下存储360 h。使用XRD谱、XPS谱和紫外-可见分光光度计、四探针测试仪表征分析薄膜的结构、在恒温恒湿条件下存储前后的表面化学状态和电学性能,研究了Ti掺杂对薄膜抗氧化性和电学性能的影响。结果表明：Ti掺杂影响MoS₂薄膜的晶体取向。随着Ti靶电流的增大薄膜的结晶性变差,Ti靶电流为0.6A时薄膜呈无定型结构且禁带宽度减小、电导率提高;在恒温恒湿条件下存储后薄膜的部分氧化而呈MoS₂与MoO₃的复合状态,随着Ti靶电流的增大I_Mo-O/I_Mo-S比提高、禁带宽度略有增大,Ti靶电流为0.4A的Ti-MoS₂薄膜其化学稳定性较高。     

金刚石/Al(或AlSi合金)复合材料性能衰退及抑制

采用气体压力浸渗法制备了金刚石/Al、金刚石/AlSi7和金刚石/AlSi9复合材料,对比研究了其暴露在空气中的性能衰退行为。研究表明,界面反应产物Al₄C₃会潮解生成Al（OH）₃,增大界面热阻,导致金刚石/Al复合材料性能衰退。Al基体中添加Si元素可以显著降低其性能衰退速率,其机制为:金刚石中C元素在Al液中溶解度的降低和Si在金刚石颗粒表面的优先析出,抑制了Al₄C₃的生成量;此外,金刚石/AlSi复合材料致密度的提高,对Al₄C₃与水汽的接触起到阻碍作用。讨论了抑制金刚石/Al复合材料性能衰退的几种可行方法,有望进一步提高其在潮湿环境中的使用寿命。      

Electron emission from nitrogen-doped polycrystalline diamond/Si heterostructures

The field electron emission from polycrystalline diamond/silicon and nitrogen-doped polycrystalline diamond/silicon structures obtained by HF CVD deposition method has been investigated. Electron emission currents from the samples were measured in a chamber at the pressure equal to 2·10^?6 Pa in sphere-to-plane diode configuration with the 5 ??m distance between electrodes. As expected, the results confirm the relation between the structure of diamond films and their emission properties. The type of silicon substrate also influences the value of emission currents and the diamond/n-Si heterostructures exhibit better electron emission than diamond/p-Si ones. The nitrogen doping significantly enhances the electron emission from the heterostructures and their emission parameters. The values of the threshold field between 2 V/??m and 3 V/??m were registered, the values of emission current close to 1 mA/cm² at 5 V/??m for the nitrogen-doped films were obtained. The shape of current-voltage characteristics for nitrogen-doped polycrystalline films may be interpreted in terms of stochastic distribution of diameters of conducting channels which form the emission centers.     

Effects of enhanced nucleation on the growth and thermal performance of diamond films deposited on BeO by hot filament CVD technique

A method of controlling the feeding concentration of methane was applied in a hot-filament chemical vapor deposition (HFCVD) in order to improve the nucleation of diamond on the beryllium oxide substrates. The nucleation density and the morphologies of diamond were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) while the thermal conductivities of substrates and the composites were detected by laser-diathermometer. The results show that the diamond thin film is in larger grain size with lower roughness when CH₄ and H₂ enter the chamber, respectively, rather than as a mixture, and the composites’ conductivity soared by 21%–31% compared with BeO substrates. At the conditions of separated gas entry, several projects with changes of the CH₄ flux during depositing were designed to discuss the influence of CH₄ concentration on diamond nucleation. The uniform and compact diamond thin films were acquired when the ratio of CH₄:H₂ at nucleation stage was in the range of 4%–8%.     

Zn2SiO4-ZnO-生物炭复合物的制备及其可见光催化H2O2降解甲硝唑

以松木碱解液代替NaOH溶液作为锌盐沉淀剂, 采用水热法制备了Zn₂SiO₄-ZnO-生物炭三元复合材料(SOB-x-y, x代表松木粉的用量, y代表NaOH浓度), 通过不同手段对样品进行表征, 研究了光催化H₂O₂降解甲硝唑的性能。结果表明, 制备的催化剂由枣核状硅锌矿型Zn₂SiO₄介晶、多边形六方晶相ZnO和松木生物炭构成; 与纯六方晶相ZnO相比, 它具有更大的比表面积与孔容、更小的带隙能和更弱的荧光发射, 因而具有更好的光催化活性。Zn₂SiO₄-ZnO-生物炭对甲硝唑的光催化H₂O₂降解过程符合准一级动力学方程, 其催化活性随NaOH浓度的增大而提高, 随松木粉用量的增加先增加后减小, 以SOB-3-4的性能最优。SOB-3-4的速率常数(k)和降解率(η)随pH的降低而增大, 随H₂O₂浓度的升高而增大, 随催化剂用量的增加先增大后减小; 甲硝唑的降解率随其初始浓度的升高逐渐越低。当初始pH为3、催化剂用量为0.4 g/L、H₂O₂投加浓度为80 mmol/L及甲硝唑初始浓度为300 mg/L时, k为2.68×10 ^-2 min ^-1, 反应3 h后η达到99.70%。本研究结果对处理难降解制药废水提供了重要的实验依据。     

高性能自支撑不锈钢网@MoS2锂离子电池负极材料

为了提高MoS₂作为Li离子电池负极材料整体的导电性和稳定性,将纳米化的MoS₂与其它导电性好的材料进行复合,通过水热法在导电基底不锈钢网(Stainless steel net, SS)上原位合成了一层MoS₂纳米花,制备了无粘结剂的自支撑结构的SS@MoS₂负极材料。纳米花状的MoS₂和导电性优异的SS提高了电子和Li离子的扩散速率,同时改善了电极的反应动力学。当作为Li离子电池负极材料时,SS@MoS₂电极表现出优异的储Li性能,特别是具有显著的大倍率充放电性能,即在1 000 mA/g的大电流密度下循环600次,比容量仍保持在862.1 mA·h/g。      

金刚石膜/氧化铝陶瓷复合材料的介电特性和热学性能研究

研究了金刚石膜/氧化铝陶瓷复合材料作为超高速、大功率集成电路封装基板材料的可行性。采用电容法测量了复合材料的介电性质,结果表明在氧化铝上沉积金刚石膜,能有效降低基片材料的介电系数。碳离子预注入处理使介电损耗降低(从5×10^-3降低到2×10^-3),且频率稳定性更好。金刚石膜的沉积可明显提高基片的热导率,随着薄膜厚度的增加,复合材料的热导率单调递增。当薄膜厚度超过100μm时复合材料的介电系数下降到6.5、热导率上升至3.98W/cm·K,热导率接近氧化铝的20倍。