纳米6H-SiC薄膜的等离子体化学气相沉积及其紫外发光

采用螺旋波等离子体化学气相沉积技术在Si(100)衬底上制备了具有纳米结构的碳化硅(SiC)薄膜.通过X射线衍射、傅里叶红外吸收和扫描电子显微镜等技术对所制备薄膜的结构、形貌以及键合特性进行了分析,利用光致发光技术研究了样品的发光特性.分析表明,在500℃的衬底温度和高氢气稀释条件下,所制备的纳米SiC薄膜红外吸收谱主要表现为SiC TO声子吸收,X射线衍射显示所制备的纳米SiC薄膜为6H结构.采用氙灯作为激发光源,不同氢气流量下所制备的样品在室温下呈现出峰值波长可变的紫外发光.     

ZnO纳米晶须的形态控制及其结构表征

采用激光分子束外延法先在Si(111)衬底上制备Zn薄膜,在不同的氧气体积流量和生长温度下,用热蒸发法在镀有Zn薄膜的Si(111)衬底上制备了不同形貌的ZnO纳米晶须。分别用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)对样品的成分、微结构和形貌进行了表征。Zn薄膜在高温下被氧化,并为晶体生长提供均匀的成核点,有利于形成一定大小和数量的ZnO晶核。研究结果表明,氧气体积流量和生长温度对ZnO纳米晶须的形貌有一定的影响。     

超长六角多型纳米SiC晶须的光学性质

采用改进的PECVD技术首次制备出六角多型SiC纳米晶须.高分辨率电镜观察其直径在18～50 nm之间,长度为0.3μm～6mm.Raman光谱表明它是六角多型(4H)纳米SiC晶须.紫外光激发出现高强度蓝光发射.同时在550～620 nm和700～750 nm处分别出现两宽带发射,经计算其中蓝光发射带,4H-SiC带隙为3.98eV,这一发光现象与量子力学计算结果不符,说明了SiC晶须光学性质的特殊性.     

纳米6H-SiC薄膜的等离子体化学气相沉积及其紫外发光

采用螺旋波等离子体化学气相沉积技术在Si(100)衬底上制备了具有纳米结构的碳化硅(SiC)薄膜.通过X射线衍射、傅里叶红外吸收和扫描电子显微镜等技术对所制备薄膜的结构、形貌以及键合特性进行了分析,利用光致发光技术研究了样品的发光特性.分析表明,在500℃的衬底温度和高氢气稀释条件下,所制备的纳米SiC薄膜红外吸收谱主要表现为SiC TO声子吸收,X射线衍射显示所制备的纳米SiC薄膜为6H结构.采用氙灯作为激发光源,不同氢气流量下所制备的样品在室温下呈现出峰值波长可变的紫外发光.     

VLS机制下SiC晶须的生长

采用化学气相沉积(CVD)法以气-液-固(VLS)机制生长了碳化硅(SiC)晶须,系统研究了基片表面的气流状况、生长温度和反应室总气压等对SiC晶须形貌的影响。研究结果表明:当基片表面存在较强的平流状态时,以生长SiC薄膜为主,很难形成晶须;生长温度及反应室总气压对晶须的直径有较大影响,合适的生长温度以及较高的总压有利于晶须的生长。     

超长六角多型纳米SiC晶须的光学性质

采用改进的PECVD技术首次制备出六角多型SiC纳米晶须. 高分辨率电镜观察其直径在18～50nm之间,长度为0.3μm～6mm. Raman光谱表明它是六角多型（4H）纳米SiC晶须. 紫外光激发出现高强度蓝光发射. 同时在550～620nm和700～750nm处分别出现两宽带发射,经计算其中蓝光发射带,4H-SiC带隙为3.98eV,这一发光现象与量子力学计算结果不符，说明了SiC晶须光学性质的特殊性.     

超长六角多型纳米SiC晶须的光学性质

采用改进的PECVD技术首次制备出六角多型SiC纳米晶须.高分辨率电镜观察其直径在18～50 nm之间,长度为0.3μm～6mm.Raman光谱表明它是六角多型(4H)纳米SiC晶须.紫外光激发出现高强度蓝光发射.同时在550～620 nm和700～750 nm处分别出现两宽带发射,经计算其中蓝光发射带,4H-SiC带隙为3.98eV,这一发光现象与量子力学计算结果不符,说明了SiC晶须光学性质的特殊性.     

SiC纳米晶/非晶复合纳米纤维的制备和场发射性能研究

采用阵列碳纳米管作为模板制备出了SiC纳米晶/非晶复合纳米纤维(以下称SiC纳米纤维),并对其晶体结构、形貌和精细结构使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HR-TEM)进行了表征.比较了SiC纳米纤维和碳纳米管模板的场发射性能,研究了SiC纳米纤维直径的变化对其绝对场增强因子的影响.结果表明:SiC纳米晶/非晶复合纳米纤维具有特殊的"树状"结构,顶端及"树枝"中分布着大量的SiC纳米晶粒.SiC纳米晶粒以及特殊的分支结构增强了SiC纳米纤维的场发射性能,开启场强低至1.1 V/μm,仅为相同直径碳纳米管模板的1/2.随着SiC纳米纤维直径的减小,绝对场增强因子β0呈明显增大趋势.     

nc-SiC/SiO_2镶嵌薄膜材料的制备、结构和发光特性

采用二氧化硅/碳化硅复合靶,用射频磁控共溅射技术和后高温退火的方法在Si(111)衬底上制备了碳化硅纳米颗粒/二氧化硅基质(nc-SiC/SiO2)镶嵌结构薄膜材料。用X射线衍射(XRD),傅里叶红外吸收(FTIR),扫描电子显微镜(SEM)和光致发光(PL)实验分析了薄膜的微结构以及光致发光特性。实验结果表明,样品薄膜经高温退火后,部分无定形SiC发生晶化,形成β-SiC纳米颗粒而较均匀地镶嵌在SiO2基质中。以280nm波长光激发薄膜表面,有较强的365nm的紫外光发射以及458nm和490nm处的蓝光发射,其发光强度随退火温度的升高显著增强,发光归结为薄膜中与Si—O相关的缺陷形成的发光中心。     

SiC薄膜的化学汽相沉积及其研究进展

介绍了SiC薄膜的一种主要制备方法———化学汽相沉积(CVD)法制备SiC薄膜的近年研究进展,并对所制备薄膜的结构特征与物理性质进行了简要评述。     

汽车尾气净化技术现状及发展

综述了汽车尾气治理的常用方法,介绍了微波技术与等离子体技术在汽车尾气净化中的应用现状，指出用微波与廉价催化剂相结合的集成净化是一个有研究和应用价值的汽车尾气治理方法。     

Modulating Trinary-Heterostructure of MoS2 via Controllably Carbon Doping for Enhanced Electrocatalytic Hydrogen Evolution Reaction

Understanding the phase transitions process of 2D transition metal dichalcogenides (2D-TMDs) from semiconducting (2H) to metallic (1T, 1T′) phase provides directionality for the iteration of hydrogen evolution catalysis. So far, the phase engineering methods are intensively explored, serving as practical tools for discovering low-cost novel nanomaterials for electronic and electrode devices in the realm of energy storage and catalysis. However, the heterostructures between 2H/1T, 2H/1T′, or 1T/1T′, functionalizing as critical active sites in the electrocatalytic process, are overlooked. Herein, a facile carbon doping paradigms, enabling augmentation of MoS₂ phase transition, together with density functional theory calculations and rationales to explain the counterintuitive directionality of transitions is reported. The experiment and simulation results indicate that the existence of carbon as interstitial atoms is more favorable to the phase transition than the substitution atoms. The heterogeneous interfaces between 2H and 1T or 1T′ are more conducive to charge transfer. As expected, the trinary-heterostructure nanofilm displays excellent electrocatalytic activities both in micro-electrochemical measurements and conventional electrolytic cells. The results provide a fresh insight into the 2D-TMDs phase transition mechanism and guide for trinary-heterostructure electrocatalysts for scalable production.     

不同碳源包覆LiFePO_4正极材料的合成及电化学性能

采用单一碳源和复合碳源,以固相反应法合成了碳包覆型LiFePO4正极材料。借助ECT、XRD、SEM和循环伏安仪对LiFePO4正极材料进行了表征,研究了不同包覆碳源对所制LiFePO4正极材料电化学性能的影响。结果表明,与使用其他碳源相比,在使用六次甲基四胺与蔗糖作为复合碳源时,LiFePO4正极材料的包覆碳量降低了40%左右;首次可逆放电容量提高了20%左右,达到141mAh/g;循环20次后的容量保持率提高了2%左右。由该种LiFePO4正极材料制作的锂离子电池具有较好的自我修复能力。     

Y-型纳米碳管的HRTEM研究

本文对Y-型纳米碳管的形貌和微观结构进行了HRTElVl表征,并探讨了其形成机理。结果表明：形成的Y-型纳米碳管内包裹Fe纳米微粒,管径分布在50—60nm之间;在反应中由于催化剂Fe纳米微粒粒径、形状和表面曲率不同,使纳米碳管在生长过程中产生分支,形成Y-型纳米碳管。     

Ordered Mesoporous C70 with Highly Crystalline Pore Walls for Energy Applications

Mesoporous materials with carbon framework structure can offer distinctive functionalities with tunable electronic or catalytic properties. Many synthetic routes including hard or soft templating approaches are developed for the fabrication of various ordered mesoporous carbon based materials which have demonstrated unique catalytic and energy storage properties. So far, most of these techniques deliver only mesoporous carbon with amorphous wall structures which limit their performance in many applications. Fullerenes exhibit unique structure and significant properties including superconductivity, electrochemical stability, and heat resistance. Herein, for the first time, the preparation of highly ordered mesoporous fullerene C₇₀ materials with tunable porous structure and controlled rod‐shaped morphology through the thermal oligomerization of fullerene C₇₀ molecules inside the mesopore channels of SBA‐15 silica as a hard template with the help of chlorinated aromatics, wherein the solubility of fullerenes is high, is reported. It is demonstrated that these metal‐free mesoporous fullerene C₇₀ framework with a high surface area and bimodal pores with multifunctionality exhibit excellent performance in the oxygen reduction reaction for fuel cells and supercapacitors. This simple strategy can also be extended to other fullerene nanostructures with different carbon atoms which can exhibit interesting physicochemical properties and find applications in catalysis and energy storage.     

In Situ Induction of Strain in Iron Phosphide (FeP2) Catalyst for Enhanced Hydroxide Adsorption and Water Oxidation

Carbon‐based materials have been widely used in heterogeneous catalysis because of their advantages of high surface area, thermal stability, and chemical inertness. However, their role in the catalysis is not fully understood although most studies conclude that the coupling between the carbon support and catalyst could reduce the charge transfer resistance and improve the kinetics of catalytic reactions such as water splitting. In this study, a carbon‐modified FeP₂ electrocatalyst with a one‐step strategy is synthesized. The tensile strain is introduced in situ in the ab crystal plane of the FeP₂ catalyst. This leads to charge redistribution between H and O atoms in the OH bonds and enhances the adsorption of reaction intermediates. In the water oxidation process, this results in a decrease in the energy barrier for the rate‐determining step, specifically, the chemical step of *OH adsorption preceded by one‐electron transfer. Benefiting from the optimized adsorption energy, the strained catalysts exhibit excellent oxygen evolution reaction (OER) activity with a low overpotential in addition to their increased stability. This study provides a new strategy for the introducing of strains in functional materials and provides new insights into the influence of carbon modification on OER activity.     

FinFET器件总剂量效应研究进展

全面综述鳍式场效应晶体管(FinFET)的总剂量效应,包括辐照期间外加偏置、器件的工艺参数、提高器件驱动能力的特殊工艺、源/漏掺杂类型以及不同栅介质材料和新沟道材料与FinFET总剂量效应的关系。对于小尺寸器件,绝缘体上硅(SOI)FinFET比体硅FinFET具有更强的抗总剂量能力,更适合于高性能抗辐照的集成电路设计。此外,一些新的栅介质材料和一些新的沟道材料的引入,如HfO₂和Ge,可以进一步提高FinFET器件的抗总剂量能力。     

室内空气净化装置研究

随着生活水平的日益提高,室内环境日益受到人们的重视。具有初效过滤网、高效过滤、活性碳过滤网同时应用光催化技术的新型空气净化装置具有良好的室内空气污染物净化作用,且无二次污染。本文针对由初、高效过滤、活性碳及光触媒组成的空气净化装置进行研究,重点讨论了高效过滤、活性碳过滤和光触媒装置。研究证明该装置具有推广应用价值。     

Winning combination [integrated gasification combined-cycle process]

This paper focuses on one of the environmentally-friendly coal-based generating technologies, the so-called integrated gasification combined-cycle (IGCC) process. This process implies the production of a synthetic gas which provides the fuel source to a gas turbine power plant operating in combined-cycle mode. The IGCC process features the inherent efficiency of combined-cycle operation, more straightforward carbon separation, and fuel flexibility including the use of biomass.     

Au Catalyzed Carbon Diffusion in Ni: A Case of Lattice Compatibility Stabilized Metastable Intermediates

Nickel is a crucial catalyst for its excellent performance in active carbon atom–related catalysis such as hydrocarbon steam reforming and 1D carbon nanostructures preparation. The carbon diffusion activity in Ni is of critical importance in understanding the catalytic behavior and thereby the performance optimization. However, the carbonization process is still vague because of the hardly identified intermediates. In this paper, the metastable intermediates of nickel carbonization process are successfully stabilized by taking advantage of the epitaxial growth to elevate the structure transformation energy barrier. X‐ray diffraction, high‐resolution transmission electron microscopy, and synchrotron X‐ray absorption near edge structure data evidence the face‐centered cubic (fcc)? Ni _x C nature of the intermediates and thus an fcc? Ni _x C‐intermediated nickel carbonization process from fcc? Ni to hexagonal close‐packed (hcp)‐Ni₃C is revealed, which is also confirmed by the Vienna ab initio simulation package calculation from the viewpoint of energy evolution. To the best of the knowledge, it is the first time to report the identification of the fcc? Ni _x C. More importantly, the introduction of Au is found promoted the catalytic growth of graphitic carbon using either oleylamine or C₂H₄ as carbon resource. The Au@Ni‐based hybrid catalysts exhibit lower reaction temperature and much higher carbon output than pure Ni.