非富勒烯受体DA'D型稠环单元的结构修饰及电池性能研究

近年来,设计和合成高性能非富勒烯受体(NFAs)材料已经成为太阳能电池研究领域的前沿课题。基于DA'D型稠环结构的NFAs由于具有吸光系数高、能级和带隙可调、结构易于修饰、分子可高效合成、光电学性能优异等优点而受到了越来越广泛的关注。在短短7年的时间里,能量转换效率(PCE)从3%~4%提高到18%。2019年初邹应萍等报道了一个优秀的受体分子Y6,与PM6共混制备单结电池,获得了15.7%的能量转换效率。Y6类受体材料的中心给电子单元为DA'D型稠环结构,缺电子单元(A')通过氮原子与两个给电子单元(D)并联形成稠环结构,这有助于降低前线分子轨道能级并增强吸收,同时与氮相连的两个烷基链和位于噻吩并噻吩β位的两个侧链则有助于提高溶解度及调节结晶性。自Y6问世以来,人们对分子的结构剪裁进行了深入的研究,并报道了数十种新的结构。在这些新的受体中,DA'D部分的结构裁剪对提高器件效率和太阳能电池的性能起着至关重要的作用。本文对A'、D单元和侧链结构修饰的研究进展进行了综述。通过选择几组受体,对最近报道的分子进行分类,并将它们的光学、电化学、电学和光电性质与精确的结构修饰相关联,从而对结构-性能关系进行全面概述。     

On local spectral properties of Hamilton type operators

In this paper, we introduce the class of Hamilton type operators and study various properties of this class. We show that every Hamilton type operator with property (β) or (δ) is decomposable. In addition, we prove that a Hamilton type operator T satisfies property (β), Dunford’s property (C) and Weyl’s theorem if and only if its adjoint does.     

Highly-efficient photosensitizer based on AIEgen-decorated porphyrin for protein photocleaving

An AIEgen decorated porphyrin(TPETPyP) was easily obtained through a one-step reaction.The bulky TPE in TPETPyP greatly impeded the intermolecular π-π stacking of the porphyrin core,which significantly suppressed aggregation-caused quenching(ACQ) effect of TPETPyP in aqueous solution.The four pyridinium salts formed in TPETPyP also render the whole molecule water solubility,which eliminated its aggregation.TPETPyP exhibited ~1 O_2 quantum yield as high as 0.85 in PBS.Moreover,it also showed high binding affinity to proteins,the major biotarget of ~1 O_2.The high ~1 O_2 quantum yield plus the great binding ability of TPETPyP toward proteins makes it a highly-efficient protein photocleaving agent.Protein electrophoresis experiments demonstrated that TPETPyP can photocleave BSA upon visible light irradiation,indicating that TPETPy P can act as a promising photosensitizer(PS) in PDT.The work here will provide a facile strategy to utilize AIEgens modified traditional PSs for photodynamic therapy(PDT).     

一维六方准晶压电材料反平面Ⅲ型裂纹电塑性分析

论文基于一维六方准晶压电材料反平面问题的基本方程,对Ⅲ型裂纹的电塑性区进行分析.采用条带模型并假设在电塑性区的切应力保持为常数,得到了电塑性区大小的表达式.这种假设方式消除了电场和应力在裂纹尖端的奇异性,这与实际情况相符合,也为一维六方准晶压电材料的断裂分析提供了理论基础.     

Evaluation of the stability of shortcut nitrification-denitrification process based on online specific oxygen uptake rate monitoring

Shortcut nitrification-denitrification (SCND) is widely concerned because of its low energy consumption and high nitrogen removal efficiency. However, the current difficulty lies in the stable maintenance of SCND performance, which leads to the challenge of large-scale application of this new denitrification technology. In this study, the nitrogen removal pathway from complete nitrification-denitrification (CND) to SCND was rapidly realized under high free ammonia (FA), high pH and low dissolved oxygen (DO) conditions. The variations of specific oxygen uptake rate (SOUR) of activated sludge in both processes were investigated by an online SOUR monitoring device. Different curves of SOUR from CND to SCND process were observed, and the ammonia peak obtained based on SOUR monitoring could be used to control aeration time accurately in SCND process. Accordingly, the SOUR ratio of ammonia oxidizing bacteria (AOB) to nitrite oxidizing bacteria (NOB) (SOUR_AOB/SOUR_NOB) was increased from 1.40 to 2.93. 16S rRNA Miseq high throughput sequencing revealed the dynamics of AOB and NOB, and the ratio of relative abundance (AOB/NOB) was increased from 1.03 to 3.12. Besides, SOUR_AOB/SOUR_NOB displayed significant correlations to ammonia removal rate (P<0.05), ammonia oxidation rate / nitrite oxidation rate (P < 0.05), nitrite accumulation rate (P < 0.05) and the relative abundance of AOB/NOB (P < 0.05). Thus, a strategy for evaluation the SCND process stability based on online SOUR monitoring is proposed, which provides a theoretical basis for optimizing the SCND performance.     

《茶经》中的中学化学课程资源

唐代陆羽撰写的《茶经》被誉为“茶叶百科全书”,是中国乃至世界上最早关于茶文化的史料,也是保留最完整、最全面的茶学专著。通过探析《茶经》中蕴含的育人价值,挖掘《茶经》中的化学课程资源。在化学教学中,将《茶经》中与化学知识契合的传统文化内容作为情境载体建立学习桥梁,从化学角度对传统文化内容进行再认识,从文化视角感受化学中蕴含的人文底蕴,帮助学习和理解化学知识,增强文化认同感和民族自豪感。依据新课标中的情境素材建议与要求,梳理了《茶经》中可与高中化学教科书相联系的内容,为创设真实的情境提供素材,利用古代茶器具与中学化学实验仪器之间的相似性创设情境。并且提出了关于中学化学教学中有效融入传统文化的几点建议。     

Ambient Preparation of Benzoxazine-based Phenolic Resins Enables Long-term Sustainable Photosynthesis of Hydrogen Peroxide

Rational design of polymer structures at the molecular level promotes the iteration of high-performance photocatalyst for sustainable photocatalytic hydrogen peroxide (H₂O₂) production from oxygen and water, which also lays the basis for revealing the reaction mechanism. Here we report a benzoxazine-based m-aminophenol-formaldehyde resin (APFac) polymerized at ambient conditions, exhibiting superior H₂O₂ yield and long-term stability to most polymeric photocatalysts. Benzoxazine structure was identified as the crucial photocatalytic active segment in APFac. Favorable adsorption of oxygen/intermediates on benzoxazine structure and commendable product selectivity accelerated the reaction kinetically in stepwise single-electron oxygen reduction reaction. The proposed benzoxazine-based phenolic resin provides the possibility of production in batches and industrial application, and sheds light on the de novo design and analysis of metal-free polymeric photocatalysts.     

Design of Hollow Nanoreactors for Size- and Shape-Selective Catalytic Semihydrogenation Driven by Molecular Recognition

Mimicking the structures and functions of cells to create artificial organelles has spurred the development of efficient strategies for production of hollow nanoreactors with biomimetic catalytic functions. However, such structure are challenging to fabricate and are thus rarely reported. We report the design of hollow nanoreactors with hollow multishelled structure (HoMS) and spatially loaded metal nanoparticles. Starting from a molecular-level design strategy, well-defined hollow multishelled structure phenolic resins (HoMS-PR) and carbon (HoMS-C) submicron particles were accurately constructed. HoMS-C serves as an excellent, versatile platform, owing to its tunable properties with tailored functional sites for achieving precise spatial location of metal nanoparticles, internally encapsulated (Pd@HoMS-C) or externally supported (Pd/HoMS-C). Impressively, the combination of the delicate nanoarchitecture and spatially loaded metal nanoparticles endow the pair of nanoreactors with size–shape-selective molecular recognition properties in catalytic semihydrogenation, including high activity and selectivity of Pd@HoMS-C for small aliphatic substrates and Pd/HoMS-C for large aromatic substrates. Theoretical calculations provide insight into the pair of nanoreactors with distinct behaviors due to the differences in energy barrier of substrate adsorption. This work provides guidance on the rational design and accurate construction of hollow nanoreactors with precisely located active sites and a finely modulated microenvironment by mimicking the functions of cells.     

Frenkel Defect-modulated Anti-thermal Quenching Luminescence in Lanthanide-doped Sc2(WO4)3

Although large amount of effort has been invested in combating thermal quenching that severely degrades the performance of luminescent materials particularly at high temperatures, not much affirmative progress has been realized. Herein, we demonstrate that the Frenkel defect formed via controlled annealing of Sc₂(WO₄)₃:Ln (Ln=Yb, Er, Eu, Tb, Sm), can work as energy reservoir and back-transfer the stored excitation energy to Ln³⁺ upon heating. Therefore, except routine anti-thermal quenching, thermally enhanced 415-fold downshifting and 405-fold upconversion luminescence are even obtained in Sc₂(WO₄)₃:Yb/Er, which has set a record of both the Yb³⁺-Er³⁺ energy transfer efficiency (>85 %) and the working temperature at 500 and 1073 K, respectively. Moreover, this design strategy is extendable to other hosts possessing Frenkel defect, and modulation of which directly determines whether enhanced or decreased luminescence can be obtained. This discovery has paved new avenues to reliable generation of high-temperature luminescence.     

Dual-Atom Catalysts Derived from a Preorganized Covalent Organic Framework for Enhanced Electrochemical Oxygen Reduction

Dual-atom catalysts (DAC) are deemed as promising electrocatalysts due to the abundant active sites and adjustable electronic structure, but the fabrication of well-defined DAC is still full of challenges. Herein, bonded Fe dual-atom catalysts (Fe₂DAC) with Fe₂N₆C₈O₂ configuration were developed through one-step carbonization of a preorganized covalent organic framework with bimetallic Fe chelation sites (Fe₂COF). The transition from Fe₂COF to Fe₂DAC involved the dissociation of the nanoparticles and the capture of atoms by carbon defects. Benefitting from the optimized d-band center and enhanced adsorption of OOH* intermediates, Fe₂DAC exhibited outstanding oxygen reduction activity with a half-wave potential of 0.898 V vs. RHE. This work will guide more fabrication of dual-atom and even cluster catalysts from preorganized COF in the future.