Structural and electronic properties of CuInSe2

Structural investigation on monocrystalline CuInSe₂ samples has been made. From the single crystal results, the space group of CuInSe₂ was confirmed to be Iˉ42d and the crystal solidification direction was investigated. Compositional uniformity of the ingots was established by EPMA and it was found that the indium concentration was greater than that for copper. Systematic annealing experiments were carried out in vacuum at different temperatures (as low as 160° C) and for different times. Large variation in resistivity was observed after the annealing treatment. P-type samples were found to convert to n-type after the heat-treatments.     

Metathesis as a versatile tool in oleochemistry

Olefin metathesis, awarded with the Nobel Prize in Chemistry 2005 for Chauvin, Grubbs and Schrock, has emerged as a powerful tool for organic as well as polymer chemistry. In oleochemistry, this reaction is well known and has been applied for many decades. Examples include the functionalization of the double bonds of different oleochemicals or the (direct) polymerization of plant oils via metathesis. More recent developments, particularly the development of better and more robust catalysts, allow for highly efficient cross‐metathesis reactions opening new possibilities for the direct introduction of chemical functionalities. Within this contribution, the development of metathesis in oleochemistry will be discussed, covering self‐metathesis as well as more recent developments in the field of cross‐metathesis that lead to desired platform chemicals.     

大功率CO_2激光器非平衡态合成WO_3／Fe_2O_3新型陶瓷催化剂──Ⅱ．WO_3／Fe_2O_3烯烃歧化反应催化剂的催化活性

用大功率ＣＯ２激光器熔制ＷＯ３／Ｆｅ２Ｏ３新型烯烃歧化反应催化剂。考查了催化剂组成、激光功率及熔炼时间与丙烯歧化反应催化活性之间的关系。     

双环戊二烯聚合反应热力学和动力学研究

研究了ＤＣＰＤ－ＷＯＣｌ４－ＡｌＥｔ３体系前阶段的反应动力学，采用ＧＣ法分析了不同反应条件下的动力学数据，发现ｌｇ（［ＤＣＰＤ］０／［ＤＣＰＤ］）￣ｔ存在线性关系，说明该体系在前段的聚合反应为一链式反应符合二级反应模型。同时还对该体系聚合反应热力学也进行了研究；对聚合反应的ΔＨｐ、ΔＳｐ、ΔＧｐ进行了讨论。     

Design and control of an olefin metathesis reactive distillation column

This paper considers the design and control of a reactive distillation column in which one reactant is consumed and two products are formed (A?B+C). The volatilities are α_B>α_A>α_C, i.e. the reactant is intermediate boiling between the two products. The metathesis of 2-pentene is considered as the demonstrative example. The column has a single feed of the intermediate boiling reactant. The distillate contains mostly light component and the bottoms mostly heavy.Three designs are considered: the base case (low-conversion/low-pressure), a low-conversion/high-pressure case and a high-conversion/high-pressure case. The base design is obtained from the literature, and the other two steady-state designs are optimized with respect to the total annual cost. All the designs are found to be openloop stable. Five control structures are studied for the base design. Then the best two structures are applied to the remaining two designs. This category of reactive distillation exhibits less challenging problems than other categories since it uses a single feed, which eliminates the need for the control structure to perfectly balance two fresh feeds.Simulation results demonstrate that effective dynamic control is provided by a control structure that uses two temperatures to maintain the purities of both product streams. No internal composition measurement is required. This structure is found to be robust and stable and rejects loads and tracks setpoints very well.     

Novel fluorescent polynorbornenes with multi-functional armed structure by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization and atom transfer radical polymerization

Novel organosoluble fluorescent polynorbornenes with multi-functional armed structure were designed and prepared by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). A bromo-containing functional norbornene (NBMBr) was prepared from the Diels-Alder reaction of cyclopentadiene and allyl bromide. The diblock copolymer of 5-(N-carbazolyl methyl)bicycle[2.2.1]hept-2-ene (CbzNB) and NBMBr was successfully prepared using living ROMP and used as a novel macroinitiator [poly(CbzNB-b-NBMBr)] for ATRP. Carbazoyl-containing multi-functional armed copolymer with poly(methyl methacrylate) (PMMA) was prepared by using poly(CbzNB-b-NBMBr) as a macroinitiator for ATRP. Strong fluorescence emissions (370-450 nm) were observed in the low excimer-forming multi-functional armed fluorescent polynorbornenes. The fact is that low excimer-forming carbazole-containing polymeric compound would apparently be favorable in photoconductive materials. The multi-functional armed structure make this compound an attractive candidate for applications as multi-modified hole transport materials in molecular electronic devices. Multi-modification could be further considered to be carried out by using such a functional bromo group at the end of multi-arms.     

Lateral WSe2 Homojunction through Metal Contact Doping: Excellent Self-powered Photovoltaic Photodetector

Here an IR-heating chemical vapor deposition (CVD) approach enabling fast 2D-growth of WSe₂ thin films is reported, and the great potential of metal contact doping in building CVD-grown WSe₂-based lateral homojunction is demonstrated by contacting with TiN/Ni metals in favor of holes/electrons injection. Shortening nanosheet channel to ≈2 µm leads to pronounced enhancement in the performance of diode. The fabricated WSe₂-based diode exhibits high rectification ratios without the need of gate modulation and can work efficiently as photovoltaic cell, with maximum open circuit voltage reaching up to 620 mV and a high power conversion efficiency over 15%, empowering it as superb self-powered photodetector for visible to near-infrared lights, with photoresponsivity over 0.5 A W⁻¹ and a fast photoresponse speed of 10 µs under 520 nm illumination. It is of practical significance to achieve well-performed photovoltaic devices with CVD-grown WSe₂ using fab-friendly metals and simple processing, which will help pave the way toward future mass production of optoelectronic chips.     

Epitaxial growth of large-area and highly crystalline anisotropic ReSe<Subscript>2</Subscript> atomic layer

The anisotropic two-dimensional (2D) layered material rhenium disulfide (ReSe2) has attracted considerable attention because of its unusual properties and promising applications in electronic and optoelectronic devices.However,because of its low lattice symmetry and interlayer decoupling,anisotropic growth and out-of-plane growth occur easily,yielding thick flakes,dendritic structure,or flower-like structure.In this study,we demonstrated a bottom-up method for the controlled and scalable synthesis of ReSe2 by van der Waals epitaxy.To achieve controllable growth,a micro-reactor with a confined reaction space was constructed by stacking two mica substrates in the chemical vapor deposition system.Within the confined reaction space,the nucleation density and growth rate of ReSe2 were significantly reduced,favoring the large-area synthesis of ReSe2 with a uniform monolayer thickness.The morphological evolution of ReSe2 with growth temperature indicated that the anisotropic growth was suppressed at a low growth temperature (＜600 ℃).Field-effect transistors employing the grown ReSe2 exhibited p-type conduction with a current ON/OFF ratio up to 10s and a hole carrier mobility of 0.98 cm2/(V.s).Furthermore,the ReSe2 device exhibited an outstanding photoresponse to near-infrared light,with responsivity up to 8.4 and 5.1 A/W for 850-and 940-nm light,respectively.This work not only promotes the large-scale application of ReSe2 in high-performance electronic devices but also clarifies the growth mechanism of low-lattice symmetry 2D materials.     

用于烯烃复分解反应的钌茚基催化剂的合成研究进展

基于钌金属的烯烃复分解反应现今已成为一种至关重要且快速有效的催化反应类型,在聚合领域以及现代有机合成的应用方面起着改革性的推进作用。作为烯烃复分解反应催化剂的一种,钌茚基催化剂在该领域得到成功应用。结合近年来钌茚基催化剂在烯烃复分解反应中的合成研究进展,简述了其发展过程,介绍了该领域创新性的研究成果,重点论述了一些新型钌茚基催化剂的合成方法,并且探讨了辅助配体的结构对催化剂稳定性和活性的影响,最后对其发展方向以及应用前景进行了展望。     

Mechanochemically assisted room temperature solid state metathesis reaction for the synthesis of MMoO4 (M = Ca, Sr and Ba)

This communication reports a novel mechanochemically assisted room temperature solid state metathesis reaction for the synthesis of submicron-size alkaline-earth molybdates crystallizing in a tetragonal Scheelite structure. The solids were characterized by powder XRD, FTIR, TGA, DTA, SEM, EDAX and TEM to ascertain their composition, phase homogeneity and morphology.