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61.
Tunable Oxygen Activation for Catalytic Organic Oxidation: Schottky Junction versus Plasmonic Effects 下载免费PDF全文
Ming Gong Shan Zhou Jiahua Hu Min Zhi Yang You Song Bai Prof. Jun Jiang Prof. Qun Zhang Prof. Xiaojun Wu Prof. Yujie Xiong 《Angewandte Chemie (International ed. in English)》2014,53(12):3205-3209
The charge state of the Pd surface is a critical parameter in terms of the ability of Pd nanocrystals to activate O2 to generate a species that behaves like singlet O2 both chemically and physically. Motivated by this finding, we designed a metal–semiconductor hybrid system in which Pd nanocrystals enclosed by {100} facets are deposited on TiO2 supports. Driven by the Schottky junction, the TiO2 supports can provide electrons for metal catalysts under illumination by appropriate light. Further examination by ultrafast spectroscopy revealed that the plasmonics of Pd may force a large number of electrons to undergo reverse migration from Pd to the conduction band of TiO2 under strong illumination, thus lowering the electron density of the Pd surface as a side effect. We were therefore able to rationally tailor the charge state of the metal surface and thus modulate the function of Pd nanocrystals in O2 activation and organic oxidation reactions by simply altering the intensity of light shed on Pd–TiO2 hybrid structures. 相似文献
62.
Back Cover: Surface Polarization Matters: Enhancing the Hydrogen‐Evolution Reaction by Shrinking Pt Shells in Pt–Pd–Graphene Stack Structures (Angew. Chem. Int. Ed. 45/2014) 下载免费PDF全文
63.
建立了饲料中克仑特罗、莱克多巴胺、喷布特罗、妥布特罗等18种β-兴奋剂的QuEChERS结合高效液相色谱-串联质谱的检测方法。饲料样品加水分散后经4%(v/v)氨水乙腈提取,加入25 mg十八烷基硅烷(C18)和50mg N-丙基乙二胺(PSA)吸附剂分散固相萃取净化后,以高效液相色谱-串联质谱进行定性和定量分析。采用Agilent Zorbax Eclipse XDB-C18(50 mm×4.6 mm,1.8μm)分析柱,以甲醇-0.1%(v/v)甲酸水溶液为流动相进行梯度洗脱,串联质谱在多反应监测(MRM)正离子模式下进行检测,基质外标法定量。结果表明,18种待测物在质量浓度为5~200μg/L范围内线性关系良好,相关系数为0.9912~0.9995;在0.05、0.1、0.5 mg/kg 3个浓度加标水平下,饲料中18种β-兴奋剂的平均回收率为78.4%~107.1%,相对标准偏差(RSD)为3.5%~12.3%,定量限(以信噪比≥10计)均为0.05 mg/kg。该方法准确、灵敏,前处理简单,可作为饲料中克仑特罗等18种β-兴奋剂筛选和确认的检测方法。 相似文献
64.
通过酚醛树酯包覆和碳热反应在富锂正极材料表面原位构建碳和尖晶石双壳保护结构, 对这种核壳结构的正极材料进行了结构和形貌表征, 并研究了其电化学性能. 研究发现, 尖晶石相为材料提供了三维锂离子迁移通道, 碳包覆层显著提高了正极材料的电子电导率, 两种效应的共同作用极大降低了材料的电化学阻抗, 提升了材料的放电比容量, 这种多壳层结构正极材料还具有优异的倍率性能, 在5C倍率下放电比容量可达到135.1 mA·h/g. 相似文献
65.
Yunong Li Lei Wang Jingxiang Low Di Wu Canyu Hu Wenbin Jiang Jun Ma Chengming Wang Ran Long Li Song Hangxun Xu Yujie Xiong 《中国化学快报》2020,31(1):231-234
Efficient catalytic system with low energy consumption exhibits increasing importance due to the upcoming energy crisis.Given this situation,it should be an admirable strategy for reducing energy input by effectively utilizing incident solar energy as a heat source during catalytic reactions.Herein,aza-fused7 r-conjugated microporous polymer(aza-CMP)with broad light absorption and high photothermal conversion efficiency was synthesized and utilized as a support for bimetallic AuPd nanocatalysts in light-driven benzyl alcohol oxidation.The AuPd nanoparticles anchored on aza-CMP(aza-CM P/Au_xPdy)exhibited excellent catalytic performance for benzyl alcohol oxidation under 50 mW/cm^2 light irradiation.The improved catalytic performance by the aza-CMP/Au_xPdy is attributed to the unique photothermal effect induced by aza-CMP,which can promote the catalytic benzyl alcohol oxidation occurring at Au Pd.This work presents a novel approach to effectively utilize solar energy for conventional catalytic reactions through photothermal effect. 相似文献
66.
Self-assembled supramolecular networks are promising spacer layer for electronic decoupling from the metal substrate.However,the mechanism behind of how the intrinsic electronic structure of spacer layers affects the adsorbate is still unclear.Here a hydrogen bonded network composed of n-type semiconducting molecules 3,4,9,10-perylene-tetracarboxylic-dianhydride(PTCDA)is prepared under ultra-high vacuum to serve as a spacer layer for functional organics C60 on Au(111).The geometric and electronic information of C60 was investigated by scanning tunneling microscopy and scanning tunneling spectroscopy(STM/STS)at 5 K.Effective decoupling from the metal surface yields an energy gap of 3.67 eV for C602nd,merely considering the HOMO-LUMO peak separation.The broadening of resonance peaks in STS measurements however indicates unneglected interlayer interactions in this hetero-organic system.Moreover,we scrutinize the nucleation sites of C60 on PTCDA layer and attribute this to the decreased diffusion capability on a less dense molecular arrangement possessing inhomogeneous spatial distribution of unoccupied molecular orbitals. 相似文献
67.
ZHANG Junjie WANG Can DUAN Ruomeng PENG Chencheng YANG Biao CAO Nan ZHANG Haiming CHI Lifeng 《高等学校化学研究》2020,36(4):685-689
The derivatives of aromatic cores bearing alkyl chains with different lengths are of potential interest in on-surface chemistry, and thus have been widely investigated both at liquid-solid interfaces and in vacuum. Here, we report on the structural evaluation of self-assembled 1,3,5-tri(4-dodecylphenyl)benzene(TDPB) molecules with increased molecular coverages on both Au(111) and Cu(111) surfaces. As observed on Au(111), rhombic and herringbone structures emerge successively depending on surface coverage. In the case of Cu(111), the same process of phase conversion is also observed, but with two distinct structures. In comparison, the self-assembled structures on Au(111) surface are packed more densely than that on Cu(111) surface under the same preparation conditions. This may fundamentally result from the higher adsorption energy of TDPB molecules on Cu(111), restricting their adjustment to optimize a thermodynamically favorable molecular packing. 相似文献
68.
Chao Wang Jiafang Piao Yujie Li Xiancheng Tian Yuanchen Dong Dongsheng Liu 《Angewandte Chemie (International ed. in English)》2020,59(35):15176-15180
The shape of eukaryotic cells is determined by the cytoskeleton associated with membrane proteins; however, the detailed mechanism of how the integral morphologies with structural stability is generated and maintained is still not fully understood. Here, based on the Frame‐Guided Assembly (FGA) strategy, we successfully prepared hetero‐liposomes with structural composition similar to that of eukaryotic cells by screening a series of transmembrane peptides as the leading hydrophobic groups (LHGs). It was demonstrated that the conformation and transmembrane mode of the LHGs played dominant roles during the FGA process. The FGA liposomes were formed with excellent stability, which may further provide evidence for the cytoskeleton–membrane protein–lipid bilayer model. Taking advantage of the biocompatibility and stability, the FGA liposomes were also applied to prepare novel drug delivery vehicles, which is promising in diagnostic imaging and cancer therapy applications. 相似文献
69.
Starch nanoparticle (SNP)‐based pressure sensitive adhesives (PSAs) with core‐shell particle morphology (starch nanoparticle core/acrylic polymer shell) are produced via seeded, semi‐batch emulsion polymerization at 15 wt% SNP loading (relative to total polymer weight) and 40 wt% latex solids. Crosslinker and chain transfer agent (CTA) are introduced to the acrylic shell polymer formulation at a range of concentrations according to a 32 factorial design to tailor the latex and adhesive properties of SNP‐based latexes. The crosslinker and CTA show no significant effect on polymerization kinetics, particle size, and viscosity. Latex gel content is predicted using an empirical model, which is a function of crosslinker and CTA concentration. Both the gel content and glass transition temperature strongly affect the adhesive properties (tack, peel strength, and shear strength) of the SNP‐based latex films. 3D response surfaces for the adhesive properties are constructed to facilitate the design of SNP‐based PSAs with desired properties. 相似文献
70.