Study of the Cost Functional for Free Material Design Problems

We study properties of the cost functional arising in free material optimization problems, with special emphasis on semicontinuity and its relation to convexity.     

Optoelectronic properties of benzotrithiophene isomers: A density functional theory study

Benzotrithiophene (BTT) isomers were investigated using density functional theory (DFT) and time‐dependent DFT (TD‐DFT) with the aim to explore their structures, linear optical properties, vertical and adiabatic ionization potentials (IP_v and IP_a), electron affinities (EA_v and EA_a), and reorganization energies (λ). The computed bond lengths and bond angles at the B3LYP/6–311+G (d, p) level of theory are in good agreement with experimental crystal structures of the known BTTs. These molecules are planar with zero dihedral angle, making them an ideal backbone for high charge mobility. The UV–visible spectra of BTT isomers are in the range 280–360 nm. All BTT isomers have low hole/electron reorganization energies, which is the main characteristic of good hole/electron transporting materials, and these isomers in turn have potential applications in the field of organic materials.     

Thermochemical investigation of Zr doping in LiNi8/12Co2/12Mn2/12O2 based on phase equilibria simulation

The doping behavior of Zr in LiNi_8/12Co_2/12Mn_2/12O₂ (LNCM) is investigated by a simulation of the phase equilibria for the Li-(M^*,Zr)-O system (M^* = Ni, Co, Mn) based on first-principles calculations followed by a thermochemical post-analysis of the resultant phase diagrams. The results indicate that the stable state at the synthetically stoichiometric composition of LNCM with Zr is a mixture of undoped LNCM with a Li₂ZrO₃ secondary phase; doping of Zr in the LNCM crystal is not thermodynamically favored. The energies of various states comprising LNCM supercells with defects, secondary phases, and Zr doping are examined, and the equilibrium doping concentration of Zr is calculated by considering the entire LNCM:Zr crystal as a statistical combination of these states. The doping concentration of Zr in the LNCM crystal is calculated to be very low, which enables balanced control between doping and coating, as recently reported through experimentation. The dopability of Zr is expected to increase with the depletion of O₂ supply during the heating of a system with a precisely controlled Li to M^* ratio, but this behavior is affected by the formation of defects, especially by M^* substitution for Li.     

Atomistic study of GaSe/Ge(111) interface formed through van der Waals epitaxy

Layered materials can be grown on various substrates through van der Waals epitaxy (vdWE) regardless of lattice mismatch. The atomistic study of the film-substrate interface in vdWE is becoming increasingly important due to their expected applications as two-dimensional (2D) materials. In this contribution, we have grown GaSe thin films on Ge(111) substrates by molecular beam epitaxy and studied the GaSe/Ge(111) interface using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Cross-sectional HAADF-STEM observations revealed that the grown layers adopt predominantly the expected wurtzite-like structure and stacking, but layers with zinc-blende-like structure, similar to Ga₂Se₃ but apparently different, and other layer stacking sequences, exist locally near the film-substrate interface. These results demonstrate that even in vdWE, structural changes can occur in the grown layers adjacent to the substrate, highlighting the importance of such interface for synthesizing and applying ultimately thin 2D materials.     

MIL-101(Fe)高效催化 β-蒎烯与甲醛的Prins缩合制备诺卜醇

通过水热晶化法制备了MIL-101(Fe)金属有机骨架材料, 利用X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR)、 热重分析(TG)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)和X射线光电子能谱(XPS)对催化剂的结构和形貌进行了表征. 结果表明, 该材料用于催化β-蒎烯与甲醛的Prins缩合制备诺卜醇反应的效果优异; 催化剂合成温度、 合成时间、 催化剂用量、 反应溶剂、 反应温度和反应时间对β-蒎烯的反应结果均有一定影响. 在相似的反应条件下, 合成的MIL-101(Fe)催化β-蒎烯制备诺卜醇反应的最佳条件为使用150 ℃下反应15 h合成的催化剂MIL-101(Fe), 在90 ℃下反应8 h得到的β-蒎烯转化率高达97.3%, 诺卜醇选择性达到96.7%.     

MOFs基材料在光催化CO2还原中的应用

系统总结了金属有机框架(MOFs)基材料在光催化还原CO₂中的最新研究进展, 其中包括MOFs直接作为光催化剂和作为复合光催化2个主要部分, 讨论了MOFs基光催化剂在催化还原CO₂方面展现出的独特优势, 并对MOFs基光催化剂的结构稳定性与CO₂转化效率等问题进行讨论与分析, 对未来发展趋势进行了展望.     

室温离子液体法合成新型三维共价有机骨架材料

采用室温离子热法合成了一种氟取代的具有五重贯穿金刚石拓扑结构的三维共价有机骨架材料(COFs), 记为JUC-515. 与高温溶剂热法不同的是, 室温离子液体法具有反应温度和压力低、 反应时间短、 操作简单、 无需催化剂和不产生有机蒸汽污染等优势. 制备的材料具有高度结晶性、 较大的孔隙率和良好的CO₂选择性吸附性能.     

NiCo_2S_4六角片作为钠离子电池负极材料的电化学性能及储钠动力学

通过共沉淀以及后续的气相硫化成功制备了横向边长约为2μm,纵向厚度约为30 nm的NiCo_2S_4六角片,并研究了其作为钠离子电池负极材料的电化学性能。电化学性能测试结果显示在1000 mA·g~(-1)的电流密度下,NiCo_2S_4电极循环60次后仍然可保持约387mAh·g~(-1)的可逆比容量。此外,NiCo_2S_4电极还具有良好的倍率性能,在200、400、800、1000和2000mA·g~(-1)的电流密度下,容量分别为542、398、347、300和217mAh·g~(-1)。通过进一步动力学机制分析发现,NiCo_2S_4电极的良好的倍率性能得益于其二维片层状结构诱导产生的赝电容。上述结果表明,NiCo_2S_4纳米六角片是一种极具潜力的钠离子电池负极材料。     

化学生物学综合实验教材建设

高质量实验教材是本科实验教学的重要保证,在创新型人才的培养中发挥着巨大的作用。本文从编写背景、指导思想、项目编写与修订等方面介绍了化学生物学综合实验教材的建设情况。该教材经历了十多年实验教学的考验,能较好满足相关学科的学生培养需要。