表面预处理对石墨烯上范德瓦耳斯外延生长GaN材料的影响

基于范德瓦耳斯外延生长的氮化镓/石墨烯材料异质生长界面仅靠较弱的范德瓦耳斯力束缚,具有低位错、易剥离等优势,近年来引起了人们的广泛关注.采用NH_3/H_2混合气体对石墨烯表面进行预处理,研究了不同NH_3/H_2比对石墨烯表面形貌、拉曼散射的影响,探讨了石墨烯在NH_3和H_2混合气氛下的表面预处理机制,最后在石墨烯上外延生长了1.6μm厚的GaN薄膜材料.实验结果表明:石墨烯中褶皱处的C原子更容易与气体发生刻蚀反应,刻蚀方向沿着褶皱进行;适当NH_3/H_2比的混合气体对石墨烯进行表面预处理可有效改善石墨烯上GaN材料的晶体质量.本研究提供了一种可有效提高GaN晶体质量的石墨烯表面预处理方法,可为进一步研究二维材料上高质量的GaN外延生长提供参考.     

碳载钴酞菁催化剂的一步法制备及其在碱性条件下对氧的电催化还原

通过固相加热,一步合成了以VulcanXC-72(碳黑)为载体的碳载钴酞菁(CoPc/C)复合催化剂,其可用作空气电极的氧还原催化剂。通过X射线衍射、红外光谱等测试技术对催化剂进行了表征。利用极化曲线和交流阻抗(EIS)方法测试了其在碱性介质(6mol/LKOH)中对氧还原的催化性能。结果显示,得到的产物为CoPc/C复合物,平均粒径30nm。以磷酸处理的碳黑为载体,在600℃下制备的CoPc/C复合催化剂表现出最佳的催化活性。以其制备的电极在空气气氛下-0.03V(Hg/HgO)电位时即可产生明显氧还原电流,-0.2V时电流密度达90×10-3A/cm2。     

高效无空穴传输层碳基钙钛矿太阳能电池的制备与性能研究

碳基钙钛矿太阳能电池因稳定性高、成本低廉而备受关注,但由于钙钛矿与碳电极之间能级匹配度不高,界面阻力大而导致效率不及金属基钙钛矿太阳能电池.本文制备了碳基无空穴传输层FTO/c-TiO₂/m-TiO₂/CH₃NH₃PbI₃/Carbon电池结构.通过对介孔二氧化钛层、钙钛矿层厚度进行优化,并对钙钛矿的薄膜形貌及钙钛矿激发电子寿命、可见光吸收度、载流子的提取与分离等进行深度分析,讨论了电池效率提升的内在机理.当介孔氧化钛层和钙钛矿层达到最优厚度时,钙钛矿太阳能电池获得了开路电压（V_oc）为0.93 V、电流密度（J_sc）为21.75 mA/cm²、填充因子为55%、光电转化效率达到11.11%.同时对电池进行了稳定性研究,在室温湿度为40%–50%的条件下放置15 d电池性能依旧稳定保持原来的95%,优于金属基钙钛矿太阳能电池,从而为碳电极钙钛矿太阳能电池的商业化发展提供了可能.     

Temperature-frequency dependence and mechanism of dielectric properties for γ-Y2Si2O7

This paper reports that single-phase γ-Y2Si2O7 is prepared via a sufficient blending and cold-pressed sintering technique from Y2O3 powder and SiO2 nanopowder. It studies the dielectric properties of γ-Y2Si2O7 as a function of the temperature and frequency. The γ-Y2Si2O7 exhibits low dielectric loss and non-Debye relaxation behaviour from 25 to 1400℃ in the range of 7.3-18 GHz. The mechanism for polarization relaxation of the as-prepared γ-Y2Si2O7 differing from that of SiO 2 is explained. Such particular dielectric properties could potentially make specific attraction for extensive practical applications.     

含N-吡啶联吡唑杂环的(磺)酰胺类化合物的设计、合成及生物活性

以氯虫酰胺结构为基础, 设计合成了一系列含N-吡啶联吡唑杂环的酰胺及磺酰胺类化合物. 所有化合物的结构均通过元素分析和 ¹H NMR确证. 生物活性测试结果表明, 部分化合物对东方粘虫(4龄幼虫)和尖音库蚊(幼虫)表现出较好的杀灭活性. 化合物4a, 4k和5b在浓度为100 mg/L时对东方粘虫(4龄幼虫)的致死率均高于50%, 化合物4g 在浓度为2 mg/L时对尖音库蚊(幼虫)的致死率达100%.     

Collisional Quantum Interference on Rotational Energy Transfer： Relation Between Integral Interference Angle and Rotational Quantum Number in Na2（A^1∑u^＋,ν=8～b^3∏0u,ν=14）-Na System

Collisional quantum interference （CQI） on rotational energy transfer was observed in Na2（A^1∑u^＋,ν=8～b^3∏0u,ν=14） system in collision with Na [Chem. Phys. Lett. 318 （2000） 107], and the degree of the interference was measured. The integral interference angle was obtaJned through theoretical calculation. We will research the factors that have effect on collisional quantum interference on rotational energy transfer in Na2（A^1∑u^＋,ν=8～b^3∏0u,ν=14）-Na system. Basing on the time-dependent first order Born approximation, and taking into account the anlsotroplc Lennard Jones interaction potentials and ＂straight-line＂ trajectory approximation, we obtain the factors that have effect on CQI in Na2-Na system, and obtain the relation between the integral interference angle and rotational quantum number.     

镍有序纳米孔洞阵列厚膜的制备和表征

以阳极氧化铝为模板,通过两步复型的方法,制备了金属镍的有序纳米孔洞阵列厚膜.镍膜的孔道彼此平行,呈六角排列,孔径约40 nm,孔洞间距80 nm,孔密度约1011个/cm2 .     

太赫兹亚波长人工结构传感应用

近年来,太赫兹科学技术在快速发展,它在毒品、爆炸物、有毒危险品等安全检查及反恐怖方面展现出独特的应用前景。常用的自由空间太赫兹时域光谱技术,尽管具有很多优越性和良好的应用前景,但影响其性能提高和进一步推广应用的一些实际问题仍然存在,如对光斑尺寸和样品体积、质量要求等。近年来,随着亚波长人工结构(包括超材料和表面等离子激元器件)的出现,为该问题的解决提供了新的契机。文章综述了作者在太赫兹亚波长人工结构器件传感应用所开展的一系列研究工作,其中包括薄膜材料传感、不同标号汽油传感以及同位素传感等,显著地提高了被测物质的探测灵敏度,同时降低了对被测物质的体积、质量要求,实现了高灵敏、微量物质传感,为太赫兹安全检查及反恐怖应用提供了技术借鉴。此外,文章还介绍了太赫兹亚波长人工结构传感器件未来的发展前景和面临的挑战。     

Axial Ligand Coordination Tuning of the Electrocatalytic Activity of Iron Porphyrin Electrografted onto Carbon Nanotubes for the Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is essential in many life processes and energy conversion systems. It is desirable to design transition metal molecular catalysts inspired by enzymatic oxygen activation/reduction processes as an alternative to noble-metal-Pt-based ORR electrocatalysts, especially in view point of fuel cell commercialization. We have fabricated bio-inspired molecular catalysts electrografted onto multiwalled carbon nanotubes (MWCNTs) in which 5,10,15,20-tetra(pentafluorophenyl) iron porphyrin (iron porphyrin FeF₂₀TPP) is coordinated with covalently electrografted axial ligands varying from thiophene to imidazole on the MWCNTs’ surface. The catalysts’ electrocatalytic activity varied with the axial coordination environment (i. e., S-thiophene, N-imidazole, and O-carboxylate); the imidazole-coordinated catalyst MWCNTs-Im-FeF₂₀TPP exhibited the highest ORR activity among the prepared catalysts. When MWCNT-Im-FeF₂₀TPP was loaded onto the cathode of a zinc−air battery, an open-cell voltage (OCV) of 1.35 V and a maximum power density (P_max) of 110 mW cm⁻² were achieved; this was higher than those of MWCNTs-Thi-FeF₂₀TPP (OCV=1.30 V, P_max=100 mW cm⁻²) and MWCNTs-Ox-FeF₂₀TPP (OCV=1.28 V, P_max=86 mW cm⁻²) and comparable with a commercial Pt/C catalyst (OCV=1.45 V, P_max=120 mW cm⁻²) under similar experimental conditions. This study provides a time-saving method to prepare covalently immobilized molecular electrocatalysts on carbon-based materials with structure–performance correlation that is also applicable to the design of other electrografted catalysts for energy conversion.     

MnS纳米线阵列上MnS花状球的水热合成

通过水热处理的方法,在氧化铝模板表面生成的MnS纳米线阵列上合成了六方相MnS花状球。利用场发射扫描电镜,透射电子显微镜,高分辨透射电子显微镜,选区电子衍射和X射线衍射对制备的样品进行了分析与表征。结果表明MnS花状球是在MnS纳米线阵列上生长的,纳米线的直径为70～80nm,与氧化铝模板的孔径一致且结晶性较好。随着阳极氧化氧化铝模板(AAO)的孔洞长度的减少,MnS花状球的数量快速增加。提出了MnS复合纳米结构可能的生长机制:氧化铝模板和反应中硫脲分解产生的H2S气体对产物的最终形貌有很重要的影响。室温光致发光光谱显示在420nm处存在一个很强的MnS带边发射峰。