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Chinese Journal of Chemistry 2016年第8期34卷 795-800页

作者： Pan Zhou dawei he Key Laboratory of Luminescence and Optical Information Ministry of Education Institute of Optoelectronic Technology Beo'ing Jiaotong University Beijing 100044 China

In this study, core-shell structured Li3V2(PO4)3/C wrapped in graphene nanosheets has been successfully prepared. The reduction of graphene oxide and the synthesis of Li3V2(PO4)3/C are carried out simultaneously using a chemical route followed by a solid-state reaction. The effects of conducting graphene are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra and electrochemical measurements. The results reveal that the graphene sheets not only form a compact and uniform coating layer throughout the Li3V2(PO4)3/C, but also stretch out and cross-link into a conducting network around the Li3V2(PO4)3/C particles. Thus, the graphene decorated Li3V2(PO4)3/C electrode exhibits superior high-rate capability and long-cycle stability. It delivers a reversible discharge capacity of 178.2 mAh·g−1 after 60 cycles at a current density of 0.1 C, and the rate performances of 176, 169.3, 156.1 and 135.7 mAh·g−1 at 1, 2, 5 and 10 C, respectively. The superior electrochemical properties make the graphene decorated Li3V2(PO4)3/C composite a promising cathode material for high-performance lithium-ion battery.

关键词： lithium-ion battery cathode material Li3V2(PO4)3/C graphene nanosheet electrochemical performance

Enhanced microwave absorption performance of MOF-derived hollow Zn-Co/C anchored on reduced graphene oxide

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Chinese Physics B 2021年第6期30卷 610-616页

作者： Yue Wang dawei he Yongsheng Wang Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiaotong UniversityBeijing 100044China

Composite materials assembled by metal/carbon nanoparticles and 2 D layered flakes can provide abundant interfaces,which are beneficial for high-performance microwave absorbers. herein, Zn-Co/C/RGO composites, composed of ZnCo metal-organic framework-derived Zn-Co/C nanoparticles and reduced graphene oxide(RGO), were obtained through a facile method. The multilayer structure was due to the introduction of hollow Zn-Co/C nanoparticles in the RGO sheets. ZnCo/C nanoparticles provided abundant polarization and dipole centers on the RGO surface, which enhanced the microwave absorption abilities. Different concentrations of RGO were introduced to optimize impedance matching. The minimum reflection loss(R_(L)) of Zn-Co/C/RGO with a thickness of 1.5 mm reached-32.56 dB with the bandwidth corresponding to R_(L) at-10 dB, which can reach 3.92 GHz, while a minimum R_(L) of-47.15 dB at 11.2 GHz was also obtained at a thickness of 2.0 mm. The electromagnetic data demonstrate that Zn-Co/C/RGO presented excellent absorption performance and has potential for application in the microwave absorption field.

关键词： microwave absorption metal nanoparticles metal-organic framework(MOF) reduced graphene oxide

Research of Luminescence Properties on MO-RE2 O3 -B2 O3: Eu, Mn(M=Mg, Ca, Sr; RE=Y, La, Gd)

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Journal of Rare Earths 2004年第z1期22卷 133-136页

作者： Liang Zhongyi he dawei Shi Yanning Ministry of Education Key Lab Lab of Materials for Information Storage and Display Institute of Photoelectron Technology Northern Jiao Tong University Beijing 100044 China

A series of phosphor of MO-RE2 O3-B2 O3: Eu, Mn ( M = Mg, Ca, Sr; RE = Y, La, Gd) were prepared and *** spectra exhibited high absorption in UV region (370 ~ 400 nm).There existed two valence states for europium ions Eu2+ and Eu 3+, the broad emission band peaking at 515 nm correspond to the 5d-4f emission transition of Eu2+ , the sharp emission peaking at 590 and 610 nm correspond to the 5D0→7FJ(J = 1,2,3,4) emission transition of Eu 3 + By the introduction of Mg and Y into MO-RE2O3-B2O3: Eu, blue-green emission was restrained ultimately and red emission peaking at 610 nm was enhanced strongly, intensity and colorimetric purity of red light were both ***, Mg1-xSrxO-Y2O3-B2O3: Eu was also researched, the introduction of Sr into MgO-Y2O3-B2O3:Eu gives rise to a shift to longer wavelengths of the position of the excitation peak, and the emission spectra varies with the increasing of x simultaneously.

关键词： luminescence long wave-UV excitation phosphor rare earths

Synthesis and Luminescence Properties of Ba2 MgSi2 O7 : Eu2+ under UV Excitation

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Journal of Rare Earths 2004年第z1期22卷 129-132页

作者： Shi Yanning he dawei Liang Zhongyi Ministry of Education Key Lab Lab of Materials for Information Storage and Display Institute of Photoelectron Technology Beijing Jiaotong University Beijing 100044 China

Eu2+ activated pyrosilicate phosphor were prepared under a reducing atmosphere by solid-state *** crystal structure of Ba2 MgSi2 O7: Eu2+ was analyzed by XRD *** excitation spectrum of Ba2MgSi2 O7; Eu2+ is composed of two broad bands centered at about 310 nm and 395 nm *** the emission spectra, the peak wavelength is at about 507 nm under 380 nm UV *** was found that the introduction of Zn2+ into Ba2MgSi2O7: Eu2+ Can effectively increase its emission intensity without changing the position of emission *** the Eu2 + and Ce3 + codoped pyrosilicate phosphor is the efficient bluish green phosphor under the excitation of long UV light and its emission intensity is stronger than Eu2+ doped pyrosilicate phosphor.

关键词： luminescence pyrosilicate long UV excitation rare earths

New BaBrCl:Eu^(2+) phosphors for X-ray image recording

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Chinese Science Bulletin 2009年第20期54卷 3639-3642页

作者： WANG YongSheng MENG XianGuo he dawei Key Laboratory of Luminescence and Optical Information Institute of Optoelectronic Technology Beijing Jiaotong University Beijing 100044 China

Photostimulated luminescence(PSL) is observed in BaBrCl:Eu2+ after X-ray irradiation at room *** is suggested by PSL stimulation spectrum and difference absorption spectrum(DAS) that F centers are formed upon X-ray irradiation and both spectra show two bands which are centered at about 550 nm and 675 nm *** enables the use of semiconductor light-emitting diodes(LED) instead of gas lasers for *** PSL intensity increases linearly with X-ray irradiation dose increasing,and the conversion efficiency is 29% that for the standard commercial storage phosphor BaFBr:Eu from Fuji imaging plate.

关键词： X射线照射荧光粉影像记录光激励发光吸收光谱铕气体激光器发光二极管

Enhanced carrier mobility in MoSe_(2) by pressure modulation

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Nano Research 2023年第11期16卷 12738-12744页

作者： Zhiying Bai he Zhang Jiaqi he dawei he Jiarong Wang Guili Li Jinxuan Bai Kun Zhao Xiaohui Yu Yongsheng Wang Xiaoxian Zhang Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiaotong UniversityBeijing 100044China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China Songshan Lake Materials Laboratory Dongguan 523808China

Two-dimensional(2D)materials hold great potential for the development of next-generation integrated circuits(ICs)at the atomic ***,it is still very challenging to build high performance *** of the main factors that limit the incorporation of 2D materials into IC technology is their relatively low carrier ***,the engineering strategies that focus on optimizing performance continue to ***,using a spatiotemporal resolved pump-probe setup,the carrier transport performance and relaxation process of few-layer and bulk MoSe_(2) under pressure were investigated nondestructively and *** results show that pressure can tune the transport performance *** particular,under pressure regulation,the carrier mobility of the bulk MoSe_(2) increases by~4 times;meanwhile,the carrier lifetimes of the samples become *** the processes almost return to their initial state after the pressure release,it is still surprising to see that the carrier mobilities of fewlayer and bulk MoSe2 are still~1.5 and 2 times enhanced,and carrier lifetimes are still shorter than the initial *** with the Raman spectra under pressure,we consider that it is caused by the enhanced layer coupling and lattice *** combination of enhanced mobility and shortened lifetime in MoSe_(2) under pressure holds great potential for optoelectronic applications under the deep ocean and deep earth.

关键词： transition metal dichalcogenides(TMDs) pressure carrier relaxation transport performance spatiotemporally resolved pump-probe spectroscopy

Effect of annealing treatment on the performance of organic photovoltaic devices using SPFGraphene as electron-accepter material

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Science China(Physics,Mechanics & Astronomy) 2012年第8期55卷 1356-1361页

作者： WANG HaiTeng he dawei WANG YongSheng LIU ZhiYong WU HongPeng WANG JiGang ZHAO Yu Key Laboratory of Luminescence and Optical Information Ministry of Education Institute of Optoelectronic Technology Beijing Jiaotong University Beijing 100044 China

We have researched the performances of organic photovoltaic devices with the bulk heterojunction （BHJ） structure using the organic solution-processable functionalized graphene （SPFGraphene） material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT：PSS/P3OT：PCBM-SPFGraphene/LiF/A1. Given the P3OT/PCBM （1：1） mixture with 8wt% of SPFGraphene, the open-circuit voltage （Voc） of the device reaches 0.64 V, a short-circuit current density （J^c） reaches 5.7 mA/cm2, a fill factor （FF） reaches 0.42, and the power conversion efficiency （7？） reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement In the P3OT：PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital （LUMO）-SPFGraphene-A1. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital （HOMO） and LUMO of the donoffacceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180℃ show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.

关键词： SPFGraphene P3OT HOMO LUMO

Preparation of long-branched polyethylene by in situ poly-merization using late transition metal and metallocene catalysts

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Chinese Science Bulletin 2001年第24期46卷 2054-2057页

作者： LIU Zhongyang GUO Cunyue MAZhi WANG Jun XU Demin he dawei HU Youliang State Key Lab of Engineering Plastics Center for Molecular ScienceInstitute of ChemistryChinese Academy of SciencesBeijing 100080China Beijing Lab of Catalysis China National Petroleum Corporation Key Lab of CatalysisBeijing 100080China

An in situ polymerization method was investigated to prepare long-branched polyethylene (LBPE) with ethylene alone and a single cocatalyst, methylalumoxane (MAO), by using a dual functional catalytic system containing late transition metal oligomerization catalyst and metal-locene copolymerization catalyst. The obtained long-branched polyethylene has the characteristics of low melting point, high activity and well-dispersed sequence distribution.

关键词： long-branched polyethylene in situ polymerization late transition metal catalyst metallocene catalyst.

Enhanced exciton diffusion from interlayer charge-transfer transitions in PtSe2/MoSe_(2) van der Waals heterojunction

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Nano Research 2023年第11期16卷 12809-12816页

作者： Jiarong Wang dawei he Zhiying Bai Guili Li Jinxuan Bai Keqin Liu Fangying Ren Xiaojing Liu Jiaqi he Weiya Zhou Jianlin Sun Yongsheng Wang Xiaoxian Zhang Yuchao Yang Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiaotong UniversityBeijing 100044China Beijing Advanced Innovation Center for Integrated Circuits School of Integrated CircuitsPeking UniversityBeijing 100871China School of Electronic and Computer Engineering Peking UniversityShenzhen 518055China Center for Brain Inspired Chips Institute for Artificial IntelligenceFrontiers Science Center for Nano-optoelectronicsPeking UniversityBeijing 100871China Center for Brain Inspired Intelligence Chinese Institute for Brain Research(CIBR)Beijing 102206China College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectronic devices at atomic ***,due to the damage caused by the device fabrication process,their inherent properties such as carrier mobility are obscured,which hinders the improvement of device performance and the incorporation of vdWs materials into next-generation integrated ***,combining pump-probe spectroscopic and scanning probe microscopic techniques,the intrinsic optoelectronic properties of PtSe_(2)/MoSe_(2)heterojunction were nondestructively and systematically *** heterojunction exhibits a broad-spectrum optical response and maintains ultrafast carrier dynamics(interfacial charge transfer~0.8 ps and carrier lifetime~38.2 ps)*** in-plane exciton diffusion coefficient of the heterojunction was extracted(19.4±7.6 cm^(2)∙s^(−1)),and its exciton mobility as high as 756.8 cm^(2)∙V−1∙s^(−1)was deduced,exceeding the value of its *** enhancement was attributed to the formation of an n-type Schottky junction between PtSe_(2)and MoSe_(2),and its built-in electric field assisted the ultrafast transfer of photogenerated carriers from MoSe_(2)to PtSe_(2),enhancing the in-plane exciton diffusion of the *** results demonstrate that PtSe_(2)/MoSe_(2)is suitable for the development of broadspectrum and sensitive optoelectronic ***,the results contribute to a fundamental understanding of the performance of various optoelectronic devices based on such PtSe_(2)two-dimensional(2D)heterostructures.

关键词： van der Waals heterostructures ultrafast carrier dynamics exciton diffusion pump-probe spectroscopy scanning probe microscopy

Designing a spatial pattern to rebalance the orientation of development and protection in Wuhan

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Journal of Geographical Sciences 2020年第4期30卷 569-582页

作者： JIN Gui SHI Xin he dawei GUO Baishu LI Zhaohua SHI Xianbin College of Urban and Environmental Sciences Central China Normal UniversityWuhan 430079China Faculty of Resources and Environmental Science Hubei UniversityWuhan 430062China Hubei Geological Survey Institute Wuhan 430030China

Patterns of spatial development and protection form a basic category of geoscience,and redesigning them is a popular subject of research in regional sustainable development that is important for ecological civilization *** authors here report a case study of Wuhan city using the circuit theory model and minimum cumulative resistance(MCR)model to rebalance its spatial protection and *** results show the following:(1)Using the density of the gross domestic product(GDP),density of population,rate of urbanization,and access to transportation as evaluation indicators,seven core areas of development in Wuhan were identified,accounting for 59%of the total number of streets,that exhibited a “circular-satellite”spatial structure.(2)According to the importance of ecosystem services,ecological sensitivity,land use type,and slope of the terrain,the resistance surface of spatial development in Wuhan had a stereoscopic spatial form of an“inverted pyramid,”with high surroundings and a low *** area of low resistance accounted for 6.64%of the total area of Wuhan.(3)Based on coupling analysis using the MCR and spatial morphological characteristics of current,nine axes of spatial development with a total area of 427.27 km2 and eight key strategic points with a total area of 40.02 km2 were *** that were prioritized for development accounted for 9.63%of Wuhan's total area.(4)By combining the characterization of the development axis with the structure of the three-level core area,we extracted the structure of spatial development of "one heart,two wings,and three belts" in *** research framework and empirical results can provide scientific guidance for the urban spatial layout,the development of regional linkages,and ecological environmental protection in China.

关键词： spatial development and protection circuit theory model minimum cumulative resistance model core area development axis Wuhan