Partial P-Type Metal Ions Doping Induced Variation of Both Crystal Structure and Oxygen Vacancy Within Cu/SnO2 Metastable Solid Solution Nanofibers for Highly Sensitive C2H2 Sensor

Partial P-type metal ions doping(PPMID) is an alternative method to further enhance the gas sensing performance of N-type metal oxides(NMOs) in contrast to that of P-N metal oxides heterojunctions, but the influences of the introduction of PPMID on the grain size and oxygen vacancies of NMOs have been rarely investigated. Herein, a simple and effective route has been demonstrated to address this problem with Cu²⁺-doped SnO₂ metastable solid solution nanofibers(CSMSSNs) as model and C₂H₂ as target molecule by combining electrospinning and calcination technique. It seems that the introduction of PPMID can also affect crystal structure and oxygen vacancies of NMOs, proven by combining X-ray diffraction(XRD) and X-ray photoelectron spectra(XPS). Thus, PPD, crystal structure and oxygen vacancies have been combined to clarify the enhanced sensing performance of Cu-doped SnO₂ metastable solid solution nanofibers angainst C₂H₂.     

大气环境下飞秒激光对铝靶烧蚀过程的研究

利用时间分辨的光阴影成像技术研究了在大气环境下飞秒激光烧蚀铝靶的动态过程. 在入射激光能量为4 mJ, 激光光斑超过1 mm时, 激光烧蚀区表面物质以近似平面冲击波形式向外喷射; 在同样激光能量下、激光光斑较小时(约0.6 mm), 激光烧蚀区以近似半球型冲击波形式向外喷射. 当激光能量比较大时(7 mJ), 发现空气的电离对于激光烧蚀靶材有着重要影响. 在光轴附近烧蚀产生的喷射物具有额外的柱状和半圆型的结构, 叠加在平面冲击波结构上.     

[2]Catenane Synthesis via Covalent Templating

After earlier unsuccessful attempts, this work reports the application of covalent templating for the synthesis of mechanically interlocked molecules (MiMs) bearing no supramolecular recognition sites. Two linear strands were covalently connected in a perpendicular fashion by a central ketal linkage. After subsequent attachment of the first strand to a template via temporary benzylic linkages, the second was linked to the template in a backfolding macrocyclization. The resulting pseudo[1]rotaxane structure was successfully converted to a [2]catenane via a second macrocyclization and cleavage of the ketal and temporary linkages.     

直接Z型LaNiO3/Mn0.2Cd0.8S异质结催化剂光解水产氢性能及机理探究

以LaNiO_3纳米颗粒为基质,在水热法制备CdS的过程中引入Mn~(2+)离子,原位合成直接Z型LaNiO_3/Mn_(0.2)Cd_(0.8)S异质结光催化剂。分别采用场发射扫描电镜、X射线衍射、X射线光电子能谱、紫外可见漫反射光谱、氮气吸附-脱附测试以及电化学测试等分析方法对制备的催化剂进行表征。在光解水产氢测试中,LaNiO_3/Mn_(0.2)Cd_(0.8)S异质结光催化剂在5 h的H_2产量达到1 190.3μmol,相较于CdS和Mn_(0.2)Cd_(0.8)S,其H_2产量分别提高了 25倍和10倍。荧光和电化学实验证实,Mn~(2+)的引入能够有效地促进光生载流子的分离,同时LaNiO_3/Mn_(0.2)Cd_(0.8)S之间异质结的构筑能有效地促进光生载流子在界面间的迁移、分离,从而促进其光解水产氢效率和稳定性的提高。结合一系列表征和活性测试结果提出直接Z型光解水反应机理,很好地阐述了其光解水产氢活性和稳定性的增强。     

基于吡嗪空穴传输层的合成及在p-i-n型钙钛矿太阳能电池中的应用

钙钛矿太阳能电池由于具有高的光电转换效率,简单的溶液加工工艺,较低的成本等优势因而拥有广阔的应用前景。有机小分子空穴传输层材料在钙钛矿太阳能电池中扮演着极其重要的角色。在本工作中,我们设计和合成了基于吡嗪为分子中心核,三苯胺为分枝的X型空穴传输层材料PT-TPA。与Si-OMeTPA对比,吡嗪的引入不仅不会影响其结晶性,并且能够改善其电荷转移特性和分子中心共平面性,从而显著提升了PT-TPA的空穴迁移率。在非掺杂的情况之下,基于PT-TPA空穴传输层的p-i-n型钙钛矿太阳能电池展现出17.52%的光电转换效率,与相同条件下基于Si-OMeTPA空穴传输层的器件相比,效率提高了近15%。     

Large‐acceptance diamond planar refractive lenses manufactured by laser cutting

For the first time, single‐crystal diamond planar refractive lenses have been fabricated by laser micromachining in 300 µm‐thick diamond plates which were grown by chemical vapour deposition. Linear lenses with apertures up to 1 mm and parabola apex radii up to 500 µm were manufactured and tested at the ESRF ID06 beamline. The large acceptance of these lenses allows them to be used as beam‐conditioning elements. Owing to the unsurpassed thermal properties of single‐crystal diamond, these lenses should be suitable to withstand the extreme flux densities expected at the planned fourth‐generation X‐ray sources.     

异质结碳纳米管的热整流效率

采用非平衡分子动力学方法, 通过分别控制异质结碳纳米管管径、手性和平均温度的方式研究了异质结碳纳米管的热整流效应. 研究表明, 随着异质结碳纳米管两端几何不对称性的增强, 其热整流效率会随之上升, 而异质结碳纳米管两端的手性的改变和夹角的大小都会对热整流效率产生一定的影响. 热整流效率会随着碳纳米管平均温度的上升而下降. 研究异质结碳纳米管热整流效率对于热二极管、碳纳米散热元器件等潜在应用价值有理论指导作用.     

用CdSe/ZnS量子点提高体异质结有机太阳电池的效率

通过掺杂吸收光谱在可见光波段的量子点可提高聚合物对可见光的吸收,因此掺杂CdSe/ZnS核-壳结构量子点(CQDs)能提高聚(3-己基噻吩):[6,6]-苯基-C61-丁酸甲酯(P3HT:PCBM)体异质结太阳电池的能量转换效率.本文研究了CdSe/ZnS量子点在P3HT:PCBM中的不同掺杂比例及其表面配体对太阳电池光伏性能的影响,优化器件ITO(氧化铟锡)/PEDOT:PSS(聚(3,4-乙撑二氧噻吩:聚苯乙烯磺酸)/P3HT:PCBM:(CdSe/ZnS)/Al的能量转换效率达到了3.99%,与相同条件下没有掺杂量子点的参考器件ITO/PEDOT:PSS/P3HT:PCBM/Al相比,其能量转换效率提高了45.1%.     

Synthesis of Bridged Oxafenestranes from Pleuromutilin

Fenestranes are an intriguing class of highly strained molecules possessing a quaternary carbon with bonds that deviate from the canonical tetrahedral geometry. Herein we report the discovery that the natural product pleuromutilin can be used as a structurally complex starting material for the synthesis of a series of bridged cis,cis,cis,cis‐[4.5.5.5]‐ and cis,cis,cis,cis‐[4.5.7.5]oxafenestranes through a carbocation rearrangement cascade. X‐ray crystallographic analysis of several cis,cis,cis,cis‐[4.5.5.5]oxafenestranes shows a significant planarization of the central tetracoordinate carbon atom and demonstrates the influence of bridgehead substituents and bridging rings on planarity.     

N‐Alkylacylamides in Thin Films Display Infrared Spectra of 310‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases

A peptide model is a physical system containing a CONH group, the simplest being HCONHCH₃, N‐methylformamide (NMF). We have discovered that NMF and N‐methylacetamide (NMA), which form hydrogen‐bonded oligomers in thin films on a planar AgX fiber, display infrared (IR) spectra with peaks like those of polypeptide helices. Structures can be assigned by their amide I maxima near 1672 (3₁₀), 1655 (3₁₀), 1653 (α), 1655 (π), and 1635 cm^?1 (π), which are the first IR data for the π‐helix. Sharp peaks are an outcome of immobilization of polar species on the polar surface of silver halides. We report the first use of expanded thin‐film IR spectroscopy, in which plots of every spectrum over the amide I–II range show pauses or slow stages in the increase or decrease of absorption. These are identified as static phases followed by dynamic phases, with the incremental gain or loss of a helix turn. A general theory can be stated for such processes. Density functional calculations show that the NMA α‐helix pentamer (crystal structure geometry) is transformed into a π‐helix‐like form. For the first time, an entire sequence (3₁₀‐helix, α‐helix, π‐helix, quasiplanar species) of spectra has been recorded for NMA.