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Simulation of gas-solid flow characteristics of the circulating fluidized bed boiler under pure-oxygen combustion conditions

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Chinese Journal of Chemical engineering 2024年第6期70卷 9-19页

作者： Kaixuan Gao Xiwei Ke Bingjun Du Zhenchuan Wang Yan Jin Zhong Huang Yanhong Li Xuemin Liu Key Laboratory of Special Equipment Safety and Energy-Saving for state Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China Department of Energy and power engineering Tsinghua UniversityBeijing 100084China School of Electrical and power engineering Taiyuan University of TechnologyTaiyuan 030024China

Under the pressure of carbon neutrality,many carbon capture,utilization and storage technologies have witnessed rapid development in the recent years,including oxy-fuel combustion(OFC)***,the conventional OFC technology usually depends on the flue gas recirculation system,which faces significant investment,high energy consumption,and potential low-temperature corrosion *** these deficiencies,the direct utilization of pure oxygen to achieve particle fluidization and fuel combustion may reduce the overall energy consumption and CO_(2)-capture *** this paper,the fundamental structure of a self-designed 130 t·h^(-1) pure-oxygen combustion circulating fluidized bed(CFB)boiler was provided,and the computational particle fluid dynamics method was used to analyze the gas-solid flow characteristics of this new-concept boiler under different working *** results indicate that through the careful selection of design or operational parameters,such as average bed-material size and fluidization velocity,the pure-oxygen combustion CFB system can maintain the ideal fluidization state,namely significant internal and external particle ***,the contraction section of the boiler leads to the particle backflow in the lower furnace,resulting in the particle suspension concentration near the wall region being higher than that in the center ***,the upper furnace still retains the classic core-annulus flow *** addition to increasing solid circulation rate by reducing the average bed-material size,altering primary gas ratio and bed inventory can also exert varying degrees of influence on the gas-solid flow characteristics of the pure-oxygen combustion CFB boiler.

关键词： Circulating fluidized bed Pure-oxygen combustion Gas-solid flow characteristics Simulation CO_(2)capture

An all-metallic nanovesicle for hydrogen oxidation

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National Science Review 2024年第06期 233-242页

作者： Juntao Zhang Lujie Jin Hao Sun Xiaozhi Liu Yujin Ji Youyong Li Wei Liu Dong Su Xuerui Liu Zhongbin Zhuang Zhiwei Hu Qi Shao Xiaoqing Huang state Key Laboratory of Physical Chemistry of solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Key Laboratory for Special Functional Materials of Ministry of Education National &Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology School of Materials Science and EngineeringCollaborative Innovation Center of Nano Functional Materials and Applications Henan University Institute of Functional Nano and Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials& Devices Soochow University state Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences state Key Lab of Organic-Inorganic Composites Beijing University of Chemical Technology Max Planck Institute for Chemical Physics of solids College of Chemistry and Chemical engineering and Materials Science Soochow University

Vesicle, a microscopic unit that encloses a volume with an ultrathin wall, is ubiquitous in ***, it remains a huge challenge to create its inorganic metal-based artificial counterparts. Here,inspired by the formation of biological vesicles, we proposed a novel biomimetic strategy of curling the ultrathin nanosheets into nanovesicles, which was driven by the interfacial strain. Trapped by the interfacial strain between the initially formed substrate Rh layer and subsequently formed RhRu overlayer, the nanosheet begins to deform in order to release a certain amount of strain. Density functional theory（DFT）calculations reveal that the Ru atoms make the curling of nanosheets more favorable in thermodynamics applications. Owing to the unique vesicular structure, the RhRu nanovesicles/C displays excellent hydrogen oxidation reaction（HOR） activity and stability, which has been proven by both experiments and DFT calculations. Specifically, the HOR mass activity of RhRu nanovesicles/C are 7.52 A mg（Rh+Ru）-1at an overpotential of 50 m V at the rotating disk electrode（RDE） level; this is 24.19 times that of commercial Pt/C(0.31 m A mgPt-1). Moreover, the hydroxide exchange membrane fuel cell（HEMFC） with RhRu nanovesicles/C displays a peak power density of 1.62 W cm-2in the H2-O2condition, much better than that of commercial Pt/C(1.18 W cm-2). This work creates a new biomimetic strategy to synthesize inorganic nanomaterials, paving a pathway for designing catalytic reactors.

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The properties of GaMnN films grown by metalorganic chemical vapour deposition using Raman spectroscopy

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Chinese Physics B 2012年第7期21卷 513-517页

作者：邢海英牛萍娟谢玉芯 School of Electronics and Information engineering Tianjin Polytechnic University engineering research center of high power solid state lighting application system School of Electrical engineering&Automation Tianjin Polytechnic University

An investigation of room-temperature Raman scattering is carried out on ferromagnetic semiconductor GaMnN films grown by metalorganic chemical vapour deposition with different Mn content values. New bands around 300 and 669 cm-1, that are not observed in undoped GaN, are found. They are assigned to disorder-activated mode and local vibration mode （LYM）, respectively. After annealing, the intensity ratio between the LVM and E2（high） mode, i.e., ILVM/IE2 （high）, increases. The LO phonon-plasmon coupled （LOPC） mode is found in GaMnN, and the frequency of the LOPC mode of GaMnN shifting toward higher side is observed with the increase in the Mn doping in GaN. The ferromagnetic character and the carrier density of our GaMnN sample are discussed.

关键词： diluted magnetic semiconductor metalorganic chemical vapour deposition Ram^n scat-tering

Boosting photocatalytic water vapor splitting by the integration of porous g-C_(3)N_(4)and carbonized melamine foam

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Science China Materials 2024年第9期67卷 2957-2964页

作者： Shujian Wang Dongjie Liu Chunyang Zhang Jie Huang Shidong Zhao Kejian Lu Biao Wang Hao Peng Yitao Si Maochang Liu International research center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an710049China School of Chemistry and Chemical engineering Southeast UniversityNanjing211189China Suzhou Academy of Xi’an Jiaotong University Suzhou215123China Gree Altairnano New Energy Inc. Zhuhai519040China

We report a photothermally-induced liquid-solid/gas-solid-decoupling photocatalytic water-splitting system,where a carbonized melamine foam(CMF)and a porous g-C_(3)N_(4)(PCN)serve as the photothermal substrate and model photocatalyst,***,liquid water is transformed into the gaseous phase over the CMF due to the photothermal effect,and the generated vapor can be split into hydrogen by PCN via the *** unique biphasic photocatalytic system exhibits a high hydrogen production rate of 368.1µmol h^(-1),which is 2.4 and 25.6 times larger than those of the traditional triphasic PCN system(151.7µmol h^(-1))and g-C_(3)N_(4)(CN)system(14.4µmol h^(-1)),*** improved photocatalytic performance is mainly attributed to the optimized energy and mass transfer at the gas-liquid-solid reaction interface,where gas products are rapidly desorbed in the photocatalytic *** work provides a novel strategy to enhance the photocatalytic performance from the perspectives of energy and mass flow.

关键词： photocatalytic photothermal mass transfer g-C_(3)N_(4) gas-solid

Deep ultraviolet light-emitting diodes based on a well-ordered AlGaN nanorod array

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Photonics research 2019年第9期7卷 941-947页

作者： LIANG ZHANG YANAN GUO JIANCHANG YAN QINGQING WU YI LU ZHUOHUI WU WEN GU XUECHENG WEI JUNXI WANG JINMIN LI research and Development center for solid state lighting Institute of SemiconductorsChinese Academy of SciencesBeijing100083China center of Materials Science and Optoelectronics engineering University of Chinese Academy of SciencesBeijing100049China Beijing engineering research center for the3rd Generation Semiconductor Materials and application Beijing100083China state Key Laboratory of solid-state lighting Beijing100083China

The nanorod structure is an alternative scheme to develop high-efficiency deep ultraviolet light-emitting diodes(DUV LEDs). In this paper, we first report the electrically injected 274-nm AlGaN nanorod array DUV LEDs fabricated by the nanosphere lithography and dry-etching technique. Nanorod DUV LED devices with good electrical properties are successfully realized. Compared to planar DUV LEDs, nanorod DUV LEDs present>2.5 times improvement in light output power and external quantum efficiency. The internal quantum efficiency of nanorod LEDs increases by 1.2 times due to the transformation of carriers from the exciton to the free electron–hole, possibly driven by the interface state effect of the nanorod sidewall surface. In addition, the nanorod array significantly facilitates photons escaping from the interior of LEDs along the vertical direction, contributing to improved light extraction efficiency. A three-dimensional finite-different time-domain simulation is performed to analyze further in detail the TE-and TM-polarized photon extraction mechanisms of the nanostructure. Our results demonstrate the nanorod structure is a good candidate for high-efficiency DUV emitters.

关键词： Deep ultraviolet light-emitting diodes based on a well-ordered AlGaN nanorod array AlGaN

Advances and prospects in nitrides based light-emitting-diodes

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Journal of Semiconductors 2016年第6期37卷 1-14页

作者：李晋闽刘喆刘志强闫建昌魏同波伊晓燕王军喜 research and Development center for solid state lighting Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China state Key Laboratory of solid state lighting Beijing 100083China Beijing engineering research center for the 3rd Generation Semiconductor Materials and application geijing 100083China

Due to their low power consumption,long lifetime and high efficiency,nitrides based white lightemitting-diodes（LEDs） have long been considered to be a promising technology for next generation *** this work,we provide a brief review of the development of GaN based *** pioneering and significant experiment results of our group and the overview of the recent progress in this field are *** hope it can provide some meaningful information for the development of high efficiency GaN based LEDs and solid-statelighting.

关键词： nitrides light-emitting-diodes MOCVD multiple-quantum-well p-doping

Fabrication and characteristics of excellent current spreading GaN-based LED by using transparent electrode-insulator-semiconductor structure

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Journal of Semiconductors 2017年第8期38卷 44-48页

作者： Chenglin Qi Yang Huang Teng Zhan Qinjin Wang Xiaoyan Yi Zhiqiang Liu Semiconductor lighting Technology research and Development center Institute of SemiconductorsState Key Laboratory of Solid State LightingBeijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application Chinese Academy of Sciences

GaN-based vertical light-emitting-diodes （V-LEDs） with an improved current injection pattern were fabricated and a novel current injection pattern of LEDs which consists of electrode-insulator-semiconductor （E1S） structure was proposed. The EIS structure was achieved by an insulator layer （20-nm Ta2O5） deposited between the p-GaN and the ITO layer. This kind of EIS structure works through a defect-assisted tunneling mechanism to realize current injection and obtains a uniform current distribution on the chip surface, thus greatly improving the current spreading ability of LEDs. The appearance of this novel current injection pattern of V-LEDs will subvert the impression of the conventional LEDs structure, including simplifying the chip manufacture technology and reducing the chip cost. Under a current density of 2, 5, 10, and 25 A/cm2, the luminous uniformity was better than conventional structure LEDs. The standard deviation of power density distribution in light distribution was 0.028, which was much smaller than that of conventional structure LEDs and illustrated a huge advantage on the current spreading ability of EIS-LEDs.

关键词： electrode-insulator-semiconductor (EIS) light emitting diodes (LEDs) tunneling mechanism lumi-nous unifomaity current spreading

Double-cliff-layer uni-traveling-carrier photodiode with high responsivity and ultra-broad bandwidth

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Chinese Optics Letters 2024年第5期22卷 100-105页

作者：韩亚茹田雨欣熊兵孙长征王健郝智彪韩彦军汪莱李洪涛甘霖罗毅 Beijing National research center for Information Science and Technology(BNRist) Department of Electronic EngineeringTsinghua UniversityBeijing 100084China Flexible Intelligent Optoelectronic Device and Technology center Institute of Flexible Electronics Technology of THUJiaxing 314006China

A novel backside-illuminated double-cliff-layer uni-traveling-carrier(DCL-UTC)photodiode with both high responsivity and ultra-broad bandwidth is designed and demonstrated.A thick absorption layer is adopted for high responsivity,and a depletion region with double cliff layers is proposed to alleviate the space charge effect and maintain overshoot electron velocity under large *** addition,inductive coplanar waveguide electrodes are employed to enhance the frequency response *** 6-μm-diameter photodiode exhibits a high responsivity of 0.51 A/W and a large 3-dB bandwidth of 102 GHz.A high RF output power of 2.7 dBm is recorded at 100 GHz.

关键词： uni-traveling-carrier photodiode high responsivity broad bandwidth

Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged backilluminated modified uni-traveling-carrier photodiode

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Opto-Electronic Science 2024年第7期3卷 20-29页

作者： Yuxin Tian Boyu Dong Yaxuan Li Bing Xiong Junwen Zhang Changzheng Sun Zhibiao Hao Jian Wang Lai Wang Yanjun Han Hongtao Li Lin Gan Nan Chi Yi Luo Beijing National research center for Information Science and Technology(BNRist) Department of Electronic EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Information Science of Electromagnetic Waves(MoE) Department of Communication Science and EngineeringFudan UniversityShanghai 200433China Flexible Intelligent Optoelectronic Device and Technology center Institute of Flexible Electronics Technology of THUJiaxing 314000China

This paper presents a wide-bandwidth back-illuminated modified uni-traveling-carrier photodiode(MUTC-PD)packaged with standard WR-5 rectangular waveguide for high-speed wireless *** optimized epitaxy structure and coplanar waveguide electrodes,the fabricated 4-μm-diameter PD exhibits ultra-flat frequency response and high saturation *** passive circuits including low-loss bias-tee and E-plane probe are designed to package the PD into a compact module with waveguide *** packaged PD module has demonstrated a flat frequency response with fluctuations within±2.75 d B over a broadband of 140–220 GHz and a high saturated output power of-7.8 d Bm(166μW)at 140 *** wireless communication applications,the packaged PD is used to implement 1-m free space transmission at carrier frequencies of 150.5 and 210.5 GHz,with transmission rates of 75 and 90 Gbps,respectively.

关键词： modified uni-traveling-carrier photodiode integrated bias-tee E-plane probe flat frequency response high saturation power WR-5 output THz wireless communications