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Growth and Electronic Properties of Ag Nanoparticles on Reduced CeO2-x（111） Films

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Chinese Journal of Chemical Physics 2012年第6期25卷 713-718,I0004页

作者： Dan-dan Kong Yong-he Pan Guo-dong Wang Hai-bin Pan jun-fa zhu National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei230029 China

Ag nanoparticles grown on reduced CeO2-x thin films have been studied by X-ray plhotoelec- tron spectroscopy and resonant photoelectron spectroscopy of the valence band to understand the effect of oxygen vacancies in the CeO2-x thin films on the growth and interracial elec- tronic properties of Ag. Ag grows as three-dimensional particles on the CeO2-x （111） surface at 300 K. Compared to the fully oxidized ceria substrate surface, Ag favors the growth of smaller particles with a larger particle density on the reduced ceria substrate surface, which can be attributed to the nucleation of Ag on oxygen vacancies. The binding energy of Ag3d increases when the Ag particle size decreases, which is mainly attributed to the final-state screening. The interracial interaction between Ag and CeO2_x（lll） is weak. The resonant enhancement of the 4f level of Ce3＋ species in RPES indicates a partial Ce4＋--＋Ce3＋ reduction after Ag deposited on reduced ceria surface. The sintering temperature of Ag on CeO 1.85 （111） surface during annealing is a little higher than that of Ag on CeO2 （111） surface, indicating that Ag nanoparticles are more stable on the reduced ceria surface.

关键词： Silver Ceria Growth Electronic structure X-ray photoelectron spectroscopy Resonant photoelectron spectroscopy

Effect of Mn Promoter on Structure and Performance of K-Co-Mo Catalyst for Synthesis of Higher Alcohols from CO Hydrogenation

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Chinese Journal of Chemical Physics 2016年第6期29卷 671-680,I0001页

作者： Wei Xie Li-li Ji Ji-long Zhou Hai-bin Pan jun-fa zhu Yi Zhang Song Sun jun Bao Chen Gao NationalSynchrotronRadiationLaboratory CollaborativeInnovationCenterofChemistryforEnergyMaterialsUniversityofScienceandTechnologyofChinaHefei230029China StateKeyLaboratoryofOrganic-InorganicComposites BellingUniversityofChemicalTechnologyBeijing100029China CASKeyLaboratoryofMaterialsforEnergyConversion DepartmentofMaterialsScienceandEngineeringUniversityofScienceandTechnologyofChinaHefei230025China

A series of Mn-doped K-Co-Mo catalysts were prepared by a sol-gel method. The catalyst structure was well characterized by X-ray diffraction, N2 physisorption, NH3 temperature- programmed adsorption, in situ diffuse reflectance infrared Fourier transform spectroscopy, and X-ray absorption fine structure spectroscopy. The catalytic performance for higher alcohol synthesis from syngas was measured. It was found that the Mn-doped catalysts ex- hibited a much higher activity as compared to the unpromoted catalyst, and in particular the C2＋ alcohol selectivity increased significantly. The distribution of alcohol products de- viated from the Anderson-Schulz-Flory law. The portion of methanol in total alcohol was suppressed remarkably and the ethanol became the predominant product. Characterization results indicated that the incorporation of Mn enhanced the interaction of Co and Mo and thus led to the formation of Co-Mo-O species, which was regarded as the active site for the alcohol synthesis. Secondly, the presence of Mn reduced the amount of strong acid sites significantly and meanwhile promoted the formation of weak acid sites, which had a positive effect on the synthesis of alcohol. Furthermore, it was found that the incorporation of Mn can enhance the adsorption of linear- and bridge-type CO significantly, which contributed to the formation of alcohol and growth of carbon chain and thus increased the selectivity to C2＋OH.

关键词： CO hydrogenation Sol-gel method Mo-based catalyst Mn promoter Higheralcohols synthesis

Interaction of cobalt with ceria thin films and its influence on supported Au nanoparticles

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Chinese Chemical Letters 2017年第8期28卷 1760-1766页

作者： Wei-Jia Wang Yan Wang Qian Xu Huan-Xin Ju Tao Wang Zhi-Jie Tao Shan-Wei Hu jun-fa zhu National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology University of Science and Technology of ChinaHefei 230029China

The interaction of Co with ceria thin films and its influence on the sintering behavior of Au were investigated by scanning tunneling microscopy（STM）, synchrotron radiation photoemission spectroscopy（SRPES） and X-ray photoelectron spectroscopy（XPS）. The strong interaction between Co and CeO_2（111） leads to oxidation of Co to Co^（2＋） at 300 K, accompanied by partial reduction of ceria surface at low Co coverages. Subsequent Co deposition results in an increasing fraction of metallic Co. Annealing to high temperatures induces Co^（2＋）ions diffuse into the CeO_2 film, while the small metallic Co islands agglomerate into larger ones. The bimetallic Co–Au particles were prepared by deposition of Au on the existing Co particles on ceria surfaces. The sintering behavior of Co–Au bimetallic surfaces is found to be highly determined by the stoichiometry of ceria supports. The addition of Co to the Au/CeO_2 surface suppresses the sintering of Au particles at high temperatures in comparison with that of pure Au particles. However, Au particles are less stable on the Co/CeO_（1.82） layer than on CeO_（1.82） surface.

关键词： Cobalt Gold Ceria SRPES XPS STM

Stability and protection of nanowire devices in air

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Nano Research 2018年第6期11卷 3353-3361页

作者： Zhen He Muhammad Hassan Huan-Xin Ju Rui Wang Jin-Long Wang Jia-Fu Chen jun-fa zhu Jian-Wei Liu Shu-Hong Yu Division of Nanomaterials & Chemistry Hefei National Laboratory for Physical Sciences at the Microscale Collaborative Innovation Center of Suzhou Nano Science and Technology Department of Chemistry CAS Center for Excellence in Nanoscience Hefei Science Center of CAS University of Science and Technology of China Hefei 230026 China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei230026 China

Nanowire devices have attracted considerable attention because of their unique structure and novel properties, and have opened up significant development opportunities. However, not many studies have focused on their stability and durability under practical conditions, which limits the rapid development of real applications. Herein, we systematically investigate three different treatments, polymer coating, inert atmosphere protection, and thickness-induced self-protection, to protect the tellurium nanowire devices from oxidation when exposed to open air. The degree of oxidation was monitored by examining changes in the valence states of tellurium element and in the morphology of the nanowires~ After the protective treatments, the tellurium nanowire devices showed improved stability and remained stable even after 800 days of storage. This work highlights the importance of investigating the stability of nanowire devices, especially for their practical applications.

关键词： stability protection tellurium nanowires nanowire devices assembly

Natural Nanofibrous Cellulose-Derived Solid Acid Catalysts

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Research 2019年第1期2019卷 1043-1053页

作者： Zhen-Yu Wu Peng Yin Huan-Xin Ju Zhi-Qin Chen Chao Li Si-Cheng Li Hai-Wei Liang jun-fa zhu Shu-Hong Yu Division of Nanomaterials&Chemistry Hefei National Laboratory for Physical Sciences at the MicroscalCAS Center for Excellence in NanoscienceHefei Science Center of CASCollaborative Innovation Center of Suzhou Nano Science and TechnologyDepartment of ChemistryUniversity of Science and Technology of ChinaHefei 230026China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230026China

Solid acid catalysts(SACs)have attracted continuous research interest in past years as they play a pivotal role in establishing environmentally friendly and sustainable catalytic processes for various chemical *** of low-cost and efcient SACs applicable to diferent catalysis processes are of immense signifcance but still very challenging so ***,we report a new kind of SACs consisting of sulfonated carbon nanofbers that are prepared via incomplete carbonization of low-cost natural nanofbrous cellulose followed by sulphonation with sulfuric *** prepared SACs feature nanofbrous network structures,high specifc surface area,and abundant sulfonate as well as hydroxyl and carboxyl ***,the nanofbrous SACs exhibit superior performance to the state-of-the-art SACs for a wide range of acid-catalyzed reactions,including dimerization of�-methylstyrene,esterifcation of oleic acid,and pinacol *** present approach holds great promise for developing new families of economic but efcient SACs based on natural precursors via scalable and sustainable protocols in the future.

关键词： holds incomplete establishing

In situ Investigations of Interfacial Degradation and Ion Migration at CH3NH3PbI3 Perovskite/Ag Interfaces

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Chinese Journal of Chemical Physics 2019年第3期32卷 299-305,I0001,I0013-I0015页

作者： Xiong Li Hong-he Ding Gui-hang Li Yan Wang Zhi-min fang Shang-feng Yang Huan-xin Ju jun-fa zhu National Synchrotron Radiation Laboratory and Department of Chemical Physics University of Science and Technology of ChinaHefei 230029China Hefei National Laboratory for Physical Sciences at the Microscale Key Laboratory of Materials for Energy ConversionChinese Academy of SciencesDepartment of Materials Science and EngineeringSynergetic Innovation Center of Quantum Information & Quantum PhysicsUniversity of Science and Technology of ChinaHefei 230026China

Interfacial properties between perovskite layers and metal electrodes play a crucial role in the device performance and the long-term stability of perovskite solar ***,we report a comprehensive study of the interfacial degradation and ion migration at the interface between CH3NH3PbI3 perovskite layer and Ag *** in situ photoemission spectroscopy measurements,we found that the Ag electrode could induce the degradation of perovskite layers,leading to the formation of PbI2 and AgI species and the reduction of Pb^2+ions to metallic Pb species at the *** unconventional enhancement of the intensities of I 3d spectra provides direct experimental evidences for the migration of iodide ions from CH3NH3PbI3 subsurface to Ag ***,the contact of Ag electrode and perovskite layers induces an interfacial dipole of 0.3 eV at CH3NH3PbI3/Ag interfaces,which may further facilitate iodide ion diffusion,resulting in the decomposition of perovskite layers and the corrosion of Ag electrode.

关键词： Perovskite solar cells Interfacial degradation Ions migration Photoemission spectroscopy

Anti-photocorrosive photoanode with RGO/PdS as hole extraction layer

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Science China Materials 2020年第10期63卷 1939-1947页

作者： Guo-Qiang Liu Yi Li Yuan Yang Feng-Jia fan Guang-Hao Ding Liang Wu jun Hu Jin-Lan Peng Qian Xu jun-fa zhu Shu-Hong Yu Division of Nanomaterials&Chemistry Hefei National Laboratory for Physical Sciences at the MicroscaleInstitute of EnergyHefei Comprehensive National Science CenterCAS Center for Excellence in NanoscienceDepartment of ChemistryInstitute of Biomimetic Materials&ChemistryUniversity of Science and Technology of ChinaHefei 230026China CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics University of Science and Technology of ChinaHefei 230026China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Center for Micro-and Nanoscale Research and fabrication University of Science and Technology of ChinaHefei 230026China

Photoelectrochemical(PEC)hydrogen production is of great interest as an ideal avenue towards clean and renewable ***,the instability and low energy conversion efficiency of photoanodes hinder their practical *** we address these issues by introducing a hole extraction layer(HEL)which could rapidly transfer and consume photogenerated *** HEL is constructed by reduced graphene oxide(RGO)and other cocatalysts that enable rapid transfer and subsequent consumption of holes,***,we showcase a high-stability photoanode composed of CdSeTe nanowires(CST NWs)and RGO/PdS nanoparticles(PdS NPs)based *** photoanode achieves excellent photocorrosion resistance,which allows stable hydrogen evolution for>2 h at 0.5 VRHE.

关键词： CdSeTe photoelectrochemistry hole extraction layer photocorrosion photoanode

Could π-aromaticity cross an unsaturated system to a fully saturated one?

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Chinese Chemical Letters 2024年第6期35卷 298-302页

作者： Shicheng Dong jun zhu State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials(iChem)Fujian Provincial Key Laboratory of Theoretical and Computational ChemistryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China School of Science and Engineering The Chinese University of Hong KongShenzhen 518172China

The classification of π-/σ-aromaticity depends on the electrons with the dominating ***,π-andσ-aromaticity are used to describe the unsaturated and saturated systems,***,it is rarely reported that π-aromaticity is dominated in a saturated *** we demonstrate that π-aromaticity could be dominating in several fully saturated four-membered rings(4MRs),supported by various aromaticity indices including ΔBL,NICS,EDDB,MCI,and Ad *** origin of suchπ-aromaticity in saturated rings could be attributed to an introduction of two additional electrons into the π-type LUMO of the parent neutral *** findings represent a novel approach to achieve π-aromaticity into a fully saturated system which has traditionally been dominated by σ-aromaticity.

关键词： π-Aromaticity Saturated rings Silicon

Topological Stability and Entropy for Certain Set-valued Maps

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Acta Mathematica Sinica,English Series 2024年第4期40卷 962-984页

作者： Yu ZHANG Yu jun zhu School of Mathematical Sciences Xiamen UniversityXiamen 361005P.R.China

In this paper,the dynamics(including shadowing property,expansiveness,topological stability and entropy)of several types of upper semi-continuous set-valued maps are mainly considered from differentiable dynamical systems points of *** is shown that(1)if f is a hyperbolic endomorphism then for eachε>0 there exists a C^(1)-neighborhood U of f such that the induced set-valued map F_(f,U)has theε-shadowing property,and moreover,if f is an expanding endomorphism then there exists a C^(1)-neighborhood U of f such that the induced set-valued map F_(f,U)has the Lipschitz shadowing property;(2)when a set-valued map F is generated by finite expanding endomorphisms,it has the shadowing property,and moreover,if the collection of the generators has no coincidence point then F is expansive and hence is topologically stable;(3)if f is an expanding endomorphism then for eachε>0 there exists a C^(1)-neighborhood U of f such that h(F_(f,U,ε))=h(f);(4)when F is generated by finite expanding endomorphisms with no coincidence point,the entropy formula of F is ***,the dynamics of the set-valued maps based on discontinuous maps on the interval are also considered.

关键词： Set-valued map orbit space hyperbolic endomorphism perturbation shadowing expansiveness topological stability entropy