Effects of Cl − on Cu 2 O nanocubes for direct epoxidation of propylene by molecular oxygen

Abstract(#br)Promoters have been widely used in industrial catalysis but understanding the mechanism behind their function is still a challenging subject. As ideal model catalysts, nanocrystal catalysts with well−defined exposing facets and relatively large specific surface have attracted intense attention. We explored the effect of Cl − loading on Cu 2 O nanocubes enclosed by (100) facets for the direct epoxidation of propylene by molecular oxygen. Interestingly, a volcano−type curve was obtained when the selectivity and conversion are plotted as a function of the loading amount of Cl − , indicating that optimal surface O/Cl − ratio is critical for desirable catalytic performance

One-step synthesis of thermally stable artificial multienzyme cascade system for efficient enzymatic electrochemical detection

Abstract(#br)Recently, metal-organic framework (MOF)-based multienzyme systems integrating different functional natural enzymes and/or nanomaterial-based artificial enzymes are attracting increasing attention due to their high catalytic efficiency and promising application in sensing. Simple and controllable integration of enzymes or nanozymes within MOFs is crucial for achieving efficient cascade catalysis and high stability. Here, we report a facile electrochemical assisted biomimetic mineralization strategy to prepare an artificial multienzyme system for efficient electrochemical detection of biomolecules. By using the GO x @Cu-MOF/copper foam (GO x @Cu-MOF/CF) architecture as a proof of concept, efficient enzyme immobilization and cascade catalysis were achieved by in situ..

Tuning electronic structure of PdZn nanocatalyst via acid-etching strategy for highly selective and stable electrolytic nitrogen fixation under ambient conditions

Abstract(#br)Although ambient nitrogen fixation powered by renewable electricity is emerging as a highly attractive alternative to the classical Haber–Bosch process, it still remains extremely challenging. In this work, a facile acid-etching strategy was employed to synthesize defect-rich PdZn nanoparticles (NPs) supported on N-doped hollow carbon polyhedrons (etched-PdZn/NHCP), which could serve as an attractive and efficient electrocatalyst for the nitrogen reduction reaction (NRR). The synthesized etched-PdZn/NHCP electrocatalyst achieved higher NH 3 yields (5.28 μg mg -1 cat. h -1 ) than pristine PdZn NPs in a phosphate buffer solution. Remarkably, the existence of abundant defects in the etched PdZn NPs favored N 2 adsorption and activation, resulting in significantly high Faradaic efficiency (FE) of 16.9% towards NH 3 and outperforming previously reported Pd-based NRR electrocatalysts. Furthermore, the etched-PdZn/NHCP cathode exhibited good long-term electrochemical durability with both the NH 3 production and the FE remaining practically stable after 50 h of electrolysis

Synthesis, phase diagram and magnetic properties of (1-x)BiFeO3-xLaMnO(3) Solid Solution

通讯作者地址: Wu, JTIn this paper, we report the syntheses of (1 - x) BiFeO3-xLaMnO(3) solid solution (x = 0-1) by an improved sol-gel method. With careful characterization of crystal structures of the as-prepared products and the phase transition as a function of temperature, the phase diagram of (1 - x) BiFeO3-xLaMnO(3) solid solution has been determined. With the increasing of x value, the crystal structure of the samples transforms from rhombohedral R3c (x 0.08).National Basic Research Program of China 2011CBA00508 2015CB932301 National Natural Science Foundation of China 21333008 21131005 2140113

Real-space imaging with pattern recognition of a ligand-protected Ag374 nanocluster at sub-molecular resolution

厦门大学化学化工学院郑南峰教授团队长期致力于研究固体功能材料的表界面化学行为，在分子水平上实现对固体功能材料的化学性能的调控与优化。得益于固体表面物理化学国家重点实验室的多学科合作以及能源材料化学协同创新中心的多单位优势互补，郑南峰教授课题组通过与校内外多个课题组的密切合作，近期在功能材料的可控制备、复杂表界面结构的高分辨表征和表界面过程分子机制的深入理解等方面取得系列重要进展，相关成果近期均在Nature Communications发表。 针对纳米颗粒表面配体难被高分辨直接成像的特点，与厦门大学郑兰荪、谢兆雄等教授以及中科院大连化物所杨学明研究员、马志博副研究员和芬兰于韦斯屈莱大学HannuHäkkinen教授等多个团队紧密合作，在利用扫描隧道显微镜表征金属纳米团簇的表面配体层结构方面取得重要进展。以原子结构精确的 Ag374纳米团簇为研究对象，利用超高真空扫描隧道显微镜分别在液氦及液氮温度下获得了单个团簇亚分子高分辨率的拓扑图像。【Abstract】High-resolution real-space imaging of nanoparticle surfaces is desirable for better understanding of surface composition and morphology, molecular interactions at the surface, and nanoparticle chemical functionality in its environment. However, achieving molecular or sub-molecular resolution has proven to be very challenging, due to highly curved nanoparticle surfaces and often insufficient knowledge of the monolayer composition. Here, we demonstrate sub-molecular resolution in scanning tunneling microscopy imaging of thiol monolayer of a 5 nm nanoparticle Ag374 protected by tert-butyl benzene thiol. The experimental data is confirmed by comparisons through a pattern recognition algorithm to simulated topography images from density functional theory using the known total structure of the Ag374 nanocluster. Our work demonstrates a working methodology for investigations of structure and composition of organic monolayers on curved nanoparticle surfaces, which helps designing functionalities for nanoparticle-based applications.The experimental work done in Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences, was supported both by Xiamen University (The National Key R&D Program of China grant 2017YFA0207302, National Natural Science Foundation of China, grant 21731005, 21420102001 and 21721001 the National Key R&D Program of China grant 2017YFA0207302) and DICP (National Natural Science Foundation of China grant 21688102, the Strategic Priority Research Program of Chinese Academy of Science, grant XDB17000000, the National Key Research and Development Program of the MOST of China, grant 2016YFA0200603 and the open fund of the state key laboratory of molecular reaction dynamics in DICP, CAS, grant SKLMRD-K201707). Q.Z. thanks Dr. Huayan Yang for providing the samples for STM imaging. S.M. and H.H. thank T. Kärkkäinen and P. Nieminen for discussions on pattern recognition algorithms. The theoretical and computational work in the University of Jyväskylä was funded by the Academy of Finland (grants 294217, 315549, AIPSE program, and H.H.’s Academy Professorship). H.H. acknowledges the support from China’s National Innovation and Intelligence Introduction Base visitor program. S.K. thanks the Vilho, Yrjö, and Kalle Väisälä Foundation for the grant for doctoral studies. The DFT simulations were done at the Finnish national supercomputing center CSC and at the Barcelona Supercomputing Center (PRACE project “NANOMETALS”). 研究工作得到了科技部、国家自然科学基金委和教育部，中科院先导项目，国家重点研发计划，分子反应动力学国家重点实验室开放课题基金等项目的资助

Rational design and SERS properties of side-by-side, end-to-end and end-to-side assemblies of Au nanorods

By taking advantage of the anisotropy of AuNRs, we design different bifunctional PEG molecules to selectively bind to either the end or side face and simultaneously protect other faces of individual AuNRs. In this way, we successfully achieve orientation-controllable assemblies of AuNRs into side-by-side (SS), end-to-end (EE) and end-to-side (ES) orientations based on the electrostatic interaction between carboxylic PEG and CTAB capping on AuNRs. Furthermore, we find that the different orientations of assembledmotifs in these three types of AuNRs assemblies exhibited different near field coupling between the surface plasma of the neighboring AuNRs, leading to different surface-enhanced Raman signals. Undoubtedly, the current rational design of oriented assembly can be potentially useful for directing anisotropic nanoparticles into well-defined orientations, which provides a powerful route in designing families of novel nanodevices and nanomaterials with programmable electrical and optical properties.National Natural Science Foundation of China[20725310, 90923042]; Research Fund for the Doctoral Program of Higher Education of China[20100121120038]; Natural Science Foundation of Fujian Province of China[2010J01046]; Fundamental Research Funds for the Central Universities[2010121023]; key laboratory of Biomedical Material of Tianji

Stabilization of anti-aromatic and strained five-membered rings with a transition metal

1981年诺贝尔化学奖获得者、美国康奈尔大学RoaldHoffmann教授评价该项工作说：'The　paper is an excellent one--it's　quite a mazing that the parent Os　system,molecule 1,chooses to give the osmapentalyne'。德国化学家Uwe Rosenthal教授等在同期《自然—化学》杂志的《News and Views》栏目以《Breaking the rules》为题撰文评述了这一研究成果。全文地址：http://www.nature.com/nchem/journal/vaop/ncurrent/pdf/nchem.1702.pdfAnti-aromatic compounds, as well as small cyclic alkynes or carbynes, are particularly challenging synthetic goals. The combination of their destabilizing features hinders attempts to prepare molecules such as pentalyne, an 8π-electron anti-aromatic bicycle with extremely high ring strain. Here we describe the facile synthesis of osmapentalyne derivatives that are thermally viable, despite containing the smallest angles observed so far at a carbyne carbon. The compounds are characterized using X-ray crystallography, and their computed energies and magnetic properties reveal aromatic character. Hence, the incorporation of the osmium centre not only reduces the ring strain of the parent pentalyne, but also converts its Hückel anti-aromaticity into Craig-type Möbius aromaticity in the metallapentalynes. The concept of aromaticity is thus extended to five-membered rings containing a metal–carbon triple bond. Moreover, these metal–aromatic compounds exhibit unusual optical effects such as near-infrared photoluminescence with particularly large Stokes shifts, long lifetimes and aggregation enhancement

The preparation of spiral ZnO nanostructures by top-down wet-chemical etching and their related properties

National Basic Research Program of China [2011CBA00508]; National Natural Science Foundation of China [21131005, 21021061, 21073145]; Key Scientific Project of Fujian Province of China [2009HZ0002-1]; Chinese Ministry of Education [212061]; Priority Academic Program Development of Jiangsu Higher Education InstitutionsIn this paper, we report the synthesis of spiral ZnO nanocrystals by the wet-chemical etching of pyramid ZnO nanoparticles in a solvent mixture of oleic acid (OA) and 1-octylamine. Adequate evidence demonstrates that the OA in the mixed solvent acts as the etching agent. The formation of spiral ZnO nanoparticles is due to dislocations in the spiral shape surrounding the c axis formed during the growth of the pyramid ZnO nanoparticles. Moreover, the spiral ZnO nanoparticles exhibit much better gas sensing activity than the pyramid ZnO nanoparticles. Based on the structural analysis, we discuss the relationship between the surface structures and gas sensing properties

Understanding the Formation of Pentagonal Cyclic Twinned Crystal from the Solvent Dependent Assembly of Au Nanocrystals into Their Colloidal Crystals

National Basic Research Program of China [2011CBA00508, 2013CB933901]; National Natural Science Foundation of China [21131005, 21021061, 21333008, 21171141]Due to the presence of high-density twinned-defects and diffuse elastic strain, pentagonal cyclic twinning (PCT) structures may have more fascinating properties than the corresponding single crystalline structure. Although there are a lot of reports concerning the PCT nanocrystals of many monometals and bimetal alloys, the established growth mechanisms of PCT structures are still not straightforward and usually inconsistent with each other. In this Letter, using dodecanethiol-capped Au nanocrystals (NCs) as building blocks, taking self-assembly of Au NCs into their colloidal crystals as the crystallization model, we found the competition of crystal cohesive energy and surface free energy plays an important role in the formation of PCT colloidal crystal. By rationally selecting the solvent to tailor the crystal cohesive energy, the structure of the colloidal crystals can be tuned. PCT structures are more likely to form when the interaction between building blocks is weak, while the single crystal structure is formed when the interaction is strong. The results demonstrate that the thermodynamic factors are the origin of pentagonal cyclic twinning