HOPG上ALD沉积Al2O3介电薄膜的生长行为研究

本文采用原子层沉积(ALD)的方法,选择三甲基铝(TMA)和H₂O₂作为反应前驱体,在高定向热解石墨(HOPG)基体上沉积Al₂O₃。系统研究了反应温度和生长周次对Al₂O₃生长行为的影响。研究表明：受HOPG表面饱和成键的影响,Al₂O₃在衬底表面处形核困难,在生长初期主要表现为台阶处择优生长,其形态为线状结构。当沉积100周次Al₂O₃时,其中在沉积温度为50 °C、150 °C和200 °C时呈现为纳米线状结构,而在100 °C时呈现为非连续薄膜。随着生长周次的增加,不同温度下沉积态Al₂O₃都趋于形成连续薄膜,表明其生长行为发生了由三维岛状生长模式向二维平面生长模式的转变。分析认为,生长模式的转变是由纳米线状结构横向生长造成的;横向生长速率主要受生长温度影响。拉曼结果表明：沉积后的石墨烯层结构未受影响,可保留其原有的优越性能。     

Photoactive Electrodes Incorporating Electrosprayed Bacterial Reaction Centers

Highly efficient light absorption and charge separation within the photosystem and reaction center (RC) complexes of photosynthetic plants and bacteria are of great interest for solar cell and photo detector applications, since they offer almost unity quantum yield and expected ultimate power conversion efficiencies of more than 18% and 12%, respectively. In addition, the charge separated states created by these protein complexes are very long lived compared to conventional semiconductor solar cells. In this work, a novel technique is presented for the deposition of photosynthetic protein complexes, by electrospraying RCs of Rhodobacter sphaeroides onto highly ordered pyrolytic graphite (HOPG) electrodes. Remarkably, it is shown that the RCs not only survive exposure to the high electric fields but also yield peak photocurrent densities of up to 7 μA cm^?2, which is equal to the highest value reported to date.     

Quasi in situ XPS study of electrochemical oxidation and reduction of highly oriented pyrolytic graphite in [1-ethyl-3-methylimidazolium][BF4] electrolytes

Highly oriented pyrolytic graphite (HOPG) electrodes were electrochemically oxidised and reduced in 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF₄] electrolytes and studied by X-ray photoelectron spectroscopy (XPS). Sample preparation and transfer have been performed under inert nitrogen atmosphere in a preparation chamber directly attached to an ultra high vacuum system. After electrochemical treatment, both, the electrolyte and the electrode surface were investigated. While on the oxidised HOPG surface the core levels of the detected elements shift towards lower energies, on the reduced samples a shift towards higher binding energies is observed. These shifts refer to a Fermi level shift proving that graphite intercalation compounds were formed. Intercalation occurs together with co-intercalation of the ionic liquid. XPS analysis of the ionic liquids before and after electrochemical treatment reveals changes in electrolyte composition. The influence of impurities on electrochemical behaviour and XPS data is discussed.     

高导热炭基功能材料研究进展

与传统的金属导热材料相比,炭基功能材料具有热导率高、密度小、耐高温、比强度和比模量高等优点,因而备受关注.主要介绍了近年来碳纤维(CF)及其复合材料、碳纳米管(CNTs)复合材料、泡沫碳、高取向热解石墨(HOPG)等高导热炭基功能材料的研究进展.     

偏压值对纳米刻蚀影响的研究

STM的刻蚀机理是通过隧道电流引发局域化学反应,以达到刻蚀的目的.在刻蚀过程中,偏压值对针尖状态的影响相当大.本文以STM为手段,研究偏压值对高序石墨表面纳米刻蚀及针尖状态的影响.通过一系列改变偏压值的纳米刻蚀试验,结果表明,在偏压值为4000mV不但刻蚀图像明显,而且对针尖状态的影响较少.     

Electrochemical reactivity at graphitic micro-domains on polycrystalline boron doped diamond thin-films electrodes

This paper deals with the electrochemical reactivity of boron doped diamond (BDD) electrodes. A comparative study has been carried out to show the influence of the presence of graphitic micro-domains upon the surface of these films. Those graphitic domains are sometimes present on as-grown boron doped diamond electrodes. The effect of doping a pure Csp³ diamond electrode is established by highly oriented pyrolytic graphite (HOPG) abrasion onto the diamond surface. In order to establish the effect of doping on a pure Csp³ diamond electrode, the amount of graphitic domains was increased by means of HOPG crystals grafted onto the BDD surface. Indeed that method allows the enrichment of the Csp² contribution of the electrode.The presence of graphitic domains can be correlatively associated with the presence of kinetically active redox sites. The electrochemical reactivity of boron doped diamond electrodes shows a distribution of kinetic constants on the whole surface of the electrode corresponding to different active sites. In this paper, we have studied by cyclic voltammetry and electrochemical impedance spectroscopy the kinetics parameters of the ferri/ferrocyanide redox couple in KCl electrolyte. A method is proposed to diagnose the presence of graphitic domains on diamond electrodes, and an electrochemical “pulse cleaning” procedure is proposed to remove them.     

快重离子在石墨中引起表面及体径迹的STM研究

用多种快重离子辐照高定向石墨（HOPG），借助扫描隧道显微镜（STM）系统地研究了表面及体内缺陷，结果表明，离子在表面及解理面上都形成了小丘状的缺陷，且在表面较容易形成，可以用非连续损伤径迹结构来对其进行解释。     

Assembly of Single-Stranded DNA Onto HOPG Surface at Different Temperature: Atomic Force Microscopy Study

Assembly of long single‐stranded DNA (ssDNA) and short oligodeoxynucleotides onto bare highly oriented pyrolytic graphite (HOPG) at different temperature has been studied. It was indicated that both long ssDNA and oligodeoxynucleotides can sequentially form network, straight chains, and layer structures when the adsorption temperature was changed from room temperature, 37–55°C. High‐resolution atomic force microscopy (AFM) imaging of the layer structures revealed that they are composed of parallel ssDNA chains with relatively higher height and tend to form patterns with three‐fold symmetry. These new findings are significantly important for understanding assembly characterization of ssDNA. In addition, this assembly method for ssDNA is expected to be used for preparation of DNA structures in biosensing and DNA‐based nanodevices. SCANNING 34: 302–308, 2012. © 2012 Wiley Periodicals, Inc.     

Data scattering in scanning tunneling spectroscopy

We investigated the scattering of current-voltage data obtained with scanning tunneling spectroscopy (STS) at room temperature at a solid-liquid interface on highly oriented pyrolytic graphite (HOPG) and in ultrahigh vacuum on HOPG and Au(111). For both experimental conditions, the data scattering can be described by a lognormal function for a moderate number of subsequent measurements. The lognormal distribution of the current can be explained by a normal distribution of the tip-surface distance. We give a simple empirical rule for STS data sorting.