原子团簇V_nP_m~+的几何结构与电子性质研究

对激光等离子体反应生成原子团簇ＶｎＰｍ＋进行了量子化学从头算研究，对可能的几何结构进行了试探性计算，并对其中较稳定构型进行了几何优化。结果表明，ＶＰｍ＋中，Ｖ倾向与双磷成键形成平面结构，其中ＶＰ＋４、ＶＰ６＋较稳定。二钒磷化物形成一个生长螺线，从Ｖ２Ｐ４＋至Ｖ２Ｐ８＋，双钒之间间隔的磷原子组成准四面体、五边形、六面体…，多钒磷化物中ＶａＰｂ＋与ＶａＰｂ＋具有相同几何构型，其中Ｖ３Ｐ３＋、Ｖ４Ｐ４＋为三钒、四钒磷化物中最稳定的构型

Interfacial Activation of Catalytically Inert Au (6.7 nm)-Fe3O4 Dumbbell Nanoparticles for CO Oxidation

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Coll Chem & Chem Engn, Dept Chem, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] nanoparticles epitaxially grown on Fe3O4 in Au (6.7 nm)-Fe3O4 dumbbell nanoparticles exhibit excellent stability against sintering, but display negligible catalytic activity in CO oxidation. Starting from various supported Au (6.7 nm)-Fe3O4 catalysts prepared by the colloidal deposition method, we have unambiguously identified the significance of the Au-TiO2 interface in CO oxidation, without any possible size effect of Au. In situ thermal decomposition of TiO2 precursors on Au-Fe3O4 was found to be an effective way to increase the Au-TiO2 interface and thereby optimize the catalytic performance of TiO2-supported Au-Fe3O4 dumbbell nanoparticles. By reducing the size of Fe3O4 from 15.2 to 4.9 nm, the Au-TiO2 contact was further increased so that the resulting TiO2-supported Au (6.7 nm)-Fe3O4 (4.9 nm) dumbbell particles become highly efficient catalysts for CO oxidation at room temperature.National Natural Science Foundation of China 20871100 20721001 Distinguished Young Investigator Grant 20925103 Research Fund for the Doctoral Program of Higher Education of China 200803841010 Natural Science Foundation of Fujian 2009J06005 Key Scientific Project of Fujian Province 2009HZ0002-

Versatile fabrication of aligned SnO2 nanotube arrays by using various ZnO arrays as sacrificial templates

通讯作者地址: Xie, ZX (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] this paper, we describe an effective two-step method for fabricating aligned SnO2 nanotube arrays by using various pre-synthesized ZnO nanorod arrays as sacrificial templates. The composition and structure of as-synthesized SnO2 nanotube arrays were analyzed in detail by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Because there is a special epitaxial relation between the SnO2 walls and ZnO templates, the walls building the SnO2 nanotubes are highly orientated and nearly single-crystalline. Our present study provides an opportunity to investigate related physical and chemical properties and potential applications of such aligned SnO2 nanotubes with nearly single-crystalline nature.National Natural Science Foundation of China 20725310,20721001 ,20673085,20801045 National Basic Research Program of China 2007CB815303 2009CB939804 Key Scientific Project of Fujian Province of China 2005HZ01-

Tailoring the optical property by a three-dimensional epitaxial heterostructure: A case of ZnO/SnO2

Epitaxial growth, as a best strategy to attain a heterostructure with a well-defined and clean interface, usually takes place on a planar substrate. In this paper, using a ZnO/SnO2 core-shell heterostructure as an example, we demonstrate the possibility of establishing a three-dimensional epitaxial interface between two materials with different crystal systems for the first time and show possible tailoring optical properties by building the heteroepitaxial crystal interface. The characterization results of element mapping, high-resolution transmission electron microscopy, and selected area electric diffraction reveal that the as-prepared ZnO/SnO2 heterostructure has a tetrapod-like ZnO core and a SnO2 shell with 15-30 nm, and their special epitaxial relation is (010)(SnO2)||(0110)(ZnO) and [100](SnO2)||[0001](ZnO). Such three-dimensional epitaxy between the ZnO core and SnO2 shell is quite different from the usual planar epitaxy or three-dimensional epitaxy between materials having the same crystal structure. A rational model of such complicated epitaxy has been proposed through investigating the certain structural comparability between the wurtzite ZnO and rutile SnO2 crystals. The as-prepared T-ZnO/SnO2 epitaxial heterostructure exhibits unique luminescence properties in contrast with individual tetrapod ZnO and SnO2 nanostructures, in which the epitaxial interface induces new luminescence properties. This result may inspire great interest in exploring other complicated epitaxy systems and their potential applications in laser, gas sensor, solar energy conversion, photo catalysis, and nanodevices in the future

Glow discharge growth of SnO2 nano-needles from SnH4

Single crystalline SnO2 nano-needles with length up to 6-7 mum and diameter less than 300 nm are synthesized on an Au-coating porous silicon substrate from SnH4 source via a glow discharge process

Desorption Electrospray Ionization Mass Spectrometry for Monitoring the Kinetics of Baeyer-Villiger Solid-State Organic Reactions

Desorption electrospray ionization mass spectrometry (DESI-MS) has been used for monitoring solid-state organic reaction in ambient air, specifically the Baeyer-Villiger (BV) type reaction involving the oxidation of ketones (benzophenone or deoxybenzoin) by m-chloroperbenzoic acid (m-CPBA) in solid-state. The DESI mass spectra obtained at regular intervals during the BV reaction processes are featured, with the amount of ester products increasing as those of ketone reactants decrease. Quantitative analyses of relative intensities of the product, made to quantify the reaction degree of typical solid-state organic reaction (SSOR), show a precision with RSDs of around 5% to 12%, though the RSDs for direct analysis of intensities of the reactant or the product in the solid-state are obviously larger. The kinetics of the Baeyer-Villiger type reactions in solid-state are shown to be dramatically different, in reaction rate, kinetic curve, as well as concentration dependence, from those of the same reactions taking place in solution.NSFC,20525103,20721001 National Basic Research Program of China (973 Program)2007CB81530

Preparation and self-assembly of copper nanoparticles via discharge of copper rod electrodes in a surfactant solution: a combination of physical and chemical processes

地址: 1. Xiamen Univ, Dept Chem, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] nanoparticles with a mean diameter of 10-15 nm were prepared and self-assembled via discharge of bulk copper rods in a cetyltrimethylammonium bromide (CTAB)/ascorbic acid solution. Ascorbic acid was used as a protective agent to prevent the nascent Cu nanoparticles from oxidation in the solution;, otherwise spindle-like Cu2O/CuO structures, with a lateral dimension of 30-50nm and length of up to 100nm, were formed in pure deionized water. The surfactant CTAB had a critical influence on self-assembly of spherical Cu nanostructures (with diameter of 700 nm-1mum). Such a low-temperature and non-vacuum method, exhibiting the characters of both physical and chemical processes, provides a versatile choice for economical preparation and assembly of various metal nanostructures. (C) 2004 Elsevier Inc. All rights reserved

Probing Hydrogen Bond Energies by Mass Spectrometry

E-mail Addresses: [email protected]; [email protected] spectrometry with desorption electrospray ionization (DESI) is demonstrated to be useful for probing the strength of hydrogen bonding, exemplified by various complexes of benzothiazoles and carboxylic acids in the solid state. Efficiencies for fragmentation of the complexes, quantified by collision-induced dissociation (CID) technology, correspond well with energies of the hydrogen bonds of O-H center dot center dot center dot N and N-H center dot center dot center dot O bridging each pair of benzothiazole and carboxylic acid. Linear correlations (with correlation factors of 0.8953 and 0.9928) have been established for the calibration curves of normalized collision energy at 100% fragmentation rate vs the length between donor and acceptor (in the hydrogen bond of O-H center dot center dot center dot N) as well as the slope of the fragmentation efficiency curve vs the average length difference between O-H center dot center dot center dot N and N-H center dot center dot center dot O in the complex. The mechanism responsible for determination of the hydrogen bonds is proposed on the basis of the experiments starting from the mixtures of the complexes as well as labeling with deuterium. As a complement of previously available methods (e.g., X-ray diffraction analysis), expectably, the proposed mass spectrometric method seems to be versatile for probing hydrogen bond energies.NNSF of China 21031004 21021061 U120511