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Switched-capacitor Based Seven-level Boost Inverter with a Reduced Number of Devices

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 381-391页

作者： Weijie Lin Jun Zeng Bo Fu Zhixing Yan junfeng.liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China WISDRI Engineering&Research Incorporation Limited Wuhan 430074China Department of Energy Aalborg UniversityAalborg 9220Denmark School of Automation Science and Engineering South China University of TechnologyGuangzhou 510641China

The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and *** by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this *** proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy *** configuration of topology and operating principles are illustrated in *** natural balance of capacitors and capacitance calculations are deduced as ***,the comparative study is conducted for different types of *** results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power ***,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.

关键词： Multilevel inverters voltage gain natural balance renewable energy generation reduced number of elements

All-optical nanoscale thermometry with silicon carbide color centers

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Photonics Research 2024年第8期12卷 1696-1702页

作者： CHENGYING liu HAIBO HU ZHENGTONG liu SHUMIN XIAO junfeng WANG YU ZHOU QINGHAI SONG Ministry of Industry and Information Technology Key Laboratory of Micro-Nano Optoelectronic Information System Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic SystemsHarbin Institute of TechnologyShenzhen 518055China Pengcheng Laboratory Shenzhen 518055China Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area Shenzhen-Hong Kong International Science and Technology ParkShenzhen 518045China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China College of Physics Sichuan UniversityChengdu 610065China

All-optical thermometry plays a crucial role in precision temperature measurement across diverse *** defects in solids are one of the most promising sensors due to their excellent sensitivity,stability,and ***,it faces limitations,such as the microwave heating effect and the complexity of spectral *** these challenges,we introduce a novel approach to nanoscale optical thermometry using quantum defects in silicon carbide(SiC),a material compatible with complementary metal-oxide-semiconductor(CMOS)*** method leverages the intensity ratio between anti-Stokes and Stokes emissions from SiC color centers,overcoming the drawbacks of traditional techniques such as optically detected magnetic resonance(ODMR)and zero-phonon line(ZPL)*** technique provides a real-time,highly sensitive(1.06%K^(-1)),and diffraction-limited temperature sensing protocol,which potentially helps enhance thermal management in the future miniaturization of electronic components.

关键词： carbide optical centers

A novel silver-doped nickel oxide hole-selective contact for crystalline silicon heterojunction solar cells

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 93-101页

作者： junfeng Zhao Xudong Yang Zhongqing Zhang Shengpeng Xie Fangfang liu Anjun Han Zhengxin liu Yun Sun Wei liu Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Engineering Research Center of Thin Film Photoelectronic TechnologyInstitute of Photoelectronic Thin Film Devices and Technology of Nankai University(Ministry of Education)Tianjin 300350China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 201800China

Based on its band alignment,p-type nickel oxide(NiO_(x))is an excellent candidate material for hole transport layers in crystalline silicon heterojunction solar cells,as it has a smallΔEV and largeΔEC with crystalline ***,to overcome the poor hole selectivity of stoichiometric NiO_(x) due to its low carrier concentration and conductivity,silver-doped nickel oxide(NiO_(x):Ag)hole transport layers with high carrier concentrations were prepared by co-sputtering high-purity silver sheets and pure NiO_(x) *** improved electrical conductivity of NiO_(x) was attributed to the holes generated by the Ag^(+)substituents for Ni^(2+),and moreover,the introduction of Ag^(+)also increased the amount of Ni^(3+)present,both of which increased the carrier concentration in NiO_(x).Ag^(+)doping also reduced the c-Si/NiO_(x) contact resistivity and improved the hole-selective contact with NiO_(x).Furthermore,the problems of particle clusters and interfacial defects on the surfaces of NiO_(x):Ag films were solved by UV-ozone oxidation and high-temperature annealing,which facilitated separation and transport of carriers at the c-Si/NiO_(x) *** constructed c-Si/NiO_(x):Ag solar cell exhibited an increase in open-circuit voltage from 490 to 596 mV and achieved a conversion efficiency of 14.4%.

关键词： band alignment nickel oxide hole transport layer silver-doped nickel oxide UV-ozone

Characteristics and sources of peroxyacetyl nitrate(PAN)in the rural North China Plain:Results from1-year continuous observations

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Journal of Environmental Sciences 2024年第4期138卷 719-731页

作者： Xin liu Xiaowei He Chenglong Zhang Yifei Song Shuyang Xie Chengtang liu Pengfei liu Yuanyuan Zhang Yujing Mu junfeng.liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sources of PAN in rural *** this study,we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP *** average concentrations of PAN were 1.10,0.75,0.65,and 0.88 ppbv in spring,summer,autumn,and winter,respectively,with a 1-year average of 0.81±0.60 *** indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN,which is an important reason for the low concentration of PAN in *** speculate that since the correlation between PAN and O_(3) in winter is significantly lower than that in other seasons,the observed regional transport of PAN cannot be ignored in *** budget analysis,regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days,respectively,which showed that regional transport played key roles during the photochemical pollution of the rural NCP in *** potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in *** winter,the transported PAN was mainly from Langfang,Hengshui,and southern *** findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.

关键词： Photochemical pollution Peroxyacetyl nitrate(PAN) Seasonal variations Regional transport Rural area

Non-perturbative dynamics of flat-band systems with correlated disorder

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Chinese Physics B 2024年第9期33卷 547-551页

作者： Qi Li junfeng.liu Ke liu Zi-Xiang Hu Zhou Li GBA Branch of Aerospace Information Research Institute Chinese Academy of SciencesGuangzhou 510535China Guangdong Provincial Key Laboratory of Terahertz Quantum Electromagnetics Guangzhou 510700China School of Physics and Materials Science Guangzhou UniversityGuangzhou 510006China Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 401331China University of Chinese Academy of Sciences Beijing 100039China

We develop a numerical method for the time evolution of Gaussian wave packets on flat-band lattices in the presence of correlated *** achieve this,we introduce a method to generate random on-site energies with prescribed *** verify this method with a one-dimensional(1D)cross-stitch model,and find good agreement with analytical results obtained from the disorder-dressed evolution *** allows us to reproduce previous findings,that disorder can mobilize 1D flat-band states which would otherwise remain *** explained by the corresponding disorder-dressed evolution equations,such mobilization requires an asymmetric disorder-induced coupling to dispersive bands,a condition that is generically not fulfilled when the flat-band is resonant with the dispersive bands at a Dirac point-like *** exemplify this with the 1D Lieb *** analytical expressions are not available for the two-dimensional(2D)system due to its complexity,we extend the numerical method to the 2D a–T3 model,and find that the initial flat-band wave packet preserves its localization when a=0,regardless of disorder and ***,when a̸=0,the wave packet shifts in real *** interpret this as a Berry phase controlled,disorder-induced wave-packet *** addition,we present density functional theory calculations of candidate materials,specifically Hg1−*** flat-band emerges near the G point(α=0)in the Brillouin zone.

关键词： flat-band system dynamics correlated disorder

Ionic liquid-trimetallic electrocatalytic system for C–O bond cleavage in lignin model compounds and lignin under ambient conditions

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Nano Research 2024年第4期17卷 2420-2428页

作者： Guangyong liu Yumiao Lu junfeng Lu Yanlei Wang Shijing Liang Hongyan He Lilong Jiang National Engineering Research Center of Chemical Fertilizer Catalyst Fuzhou UniversityFuzhou 350002China CAS Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex SystemsBeijing Key Laboratory of Ionic Liquids Clean ProcessInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China Longzihu New Energy Laboratory Zhengzhou Institute of Emerging Industrial TechnologyZhengzhou 450000China

Electrocatalytic depolymerization of lignin into value-added chemicals offers a promising technique to make biorefining ***,we report a robust trimetallic PdNiBi electrocatalyst for reductive C–O bond cleavage of different lignin model dimers and oxidized lignin under mild *** reduction reaction proceeds with complete substrate conversion and excellent yields toward monomers of phenols(80%–99%)and acetophenones(75%–96%)in the presence of an ionic liquid electrolyte with operational *** experimental investigations together with density functional theory(DFT)calculations reveal that the outstanding performance of the catalyst results from the synergistic effect of the metal elements,which facilitates the easier formation of a key Cαradical intermediate and the facile desorption of the as-formed products at the *** results open up new opportunities for lignin valorization through the green electrocatalytic approach.

关键词： electrocatalytic depolymerization lignin Ionic liquids density functional theory(DFT)calculation

Single-Component Color-Tunable Smart Organic Emitters with Simultaneous Multistage Stimuli-Responsiveness and Multimode Emissions

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Research 2024年第2期2023卷 719-728页

作者： Yu Yan Chengfang liu Jianzhong Fan Yusheng Li Huanling liu Qian Wang Xiangchun Lil junfeng Li Wen-Yong Lai State Key Laboratory of Organic Electronics and Information Displays(SKLOEID) Institute of Advanced Materials(IAM)School of Chemistry and Life SciencesNanjing University of Posts&Telecommunications9 Wenyuan RoadNanjng 210023China Shandong Province Key Laboratory of Medical Physics and Image Processing Technology School of Physics and ElectronicsShandong Normal UniversityJinan 250358China

Achieving color-tunable emission in single-component organic emitters with multistage stimuli-responsiveness is of vital significance for intelligent optoelectronic applications,but remains enormously ***,we present an unprecedented example of a color-tunable single-component smart organic emitter(DDOP)that simultaneously exhibits multistage stimuli-responsiveness and multimode *** based on a highly twisted amide-bridged donor-tcceptor-donor structure has been found to facilitate intersystem crossing,form multimode emissions,and generate multiple emissive species with multistage *** pristine crystalline powders exhibit abnormal excitation-dependent emissions from a monomer-dominated blue emission centered at 470 nm to a dimer-dominated yellow emission centered at 550 nm through decreasing the ultraviolet(UV)excitation wavelengths,whereas DDOP single crystals show a wide emission band with a main emission peak at 585 nm when excited at different *** emission behaviors of pristine crystalline powders and single crystals are different,demonstrating emission features that are closely related to the aggregation *** work has developed color-tunable single-component organic emitters with simultaneous multistage stimuli-responsiveness and multimode emissions,which is vital for expanding intelligent optoelectronic applications,including multilevel information encryption,multicolor emissive patterns,and visual monitoring of UV wavelengths.

关键词： donor excitation Smart

Yolk-shell FeCu/NC electrocatalyst boosting high-performance zinc-air battery

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Nano Research 2024年第9期17卷 7918-7925页

作者： Chen Liang Tianyu Zhang Shilun Sun Aijuan Han Zenghui Qiu Haijun Xu junfeng.liu State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China College of Mathematics&Physics Beijing University of Chemical TechnologyBeijing 100029China Beijing Bioprocess Key Laboratory Beijing University of Chemical TechnologyBeijing 100029China

Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further ***,additional structural optimization is necessary to enhance mass transport and achieve higher power density in practical ***,using ZIF-8 as a template,we synthesized yolk-shell catalysts featuring complex sites of Fe single atoms and Cu nanoclusters(y-FeCu/NC)via partial etching and liquid-phase *** synthesized y-FeCu/NC catalyst exhibits high specific surface area and mesoporous *** with the advantages of highly active sites and yolk-shell structure,the y-FeCu/NC catalyst demonstrated outstanding catalytic performance in the oxygen reduction reaction,achieving a half-wave potential(E_(1/2))of 0.97 V in 0.1 M *** a practical energy device,Zn-air battery(ZAB)assembled with y-FeCu/NC catalyst achieved a remarkable power density of 356.3 mW·cm^(-2),representing an improvement of approximately 28.5%compared to its solid FeCu/NC ***,it showcased impressive stability,surpassing all control samples.

关键词： atomic Fe-N4 sites Cu nanoclusters yolk-shell structure oxygen reduction reaction zinc-air battery

Microstructures and Properties of Biomedical Mg-Zn-Sn-Zr Rolled Alloys

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 766-773页

作者：周生刚 ZHANG Daxin XU Yang DUAN Jihao LI Tao liu junfeng WANG Peng 曹勇 Faculty of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093China

The as-cast Mg-2.0Zn-1.5Sn-xZr(x=0,0.4,0.6,0.8,1.0 wt%)alloy was rolled with the pressure less than 5%each *** microstructure,mechanical properties,corrosion properties and biocompatibility of the alloy were *** microstructure of the alloy was observed and analyzed by scanning electron microscope,and the tensile test was carried out by universal tensile *** corrosion resistance of the alloy in Hank's solution was studied by hydrogen evolution experiment and electrochemical test,and the biocompatibility of the alloy was tested by L929 *** results show that Mg-2Zn-1.5Sn-xZr alloy has excellent mechanical *** elongation of Mg-2Zn-1.5Sn-xZr alloy decreases with the increase of Zr content,but the tensile strength first increases and then decreases with the increase of Zr *** the Zr content is 0.8 wt%,the maximum tensile strength of the alloy is 235 *** results of hydrogen evolution experiment and electrochemical analysis show that the corrosion resistance of the alloy is the best when the Zr content is 0.8 wt%,and all the five alloys have high *** conclusion,the rolled alloy has good properties and has broad application prospects in the field of biomaterials.

关键词： magnesium alloy corrosion performance mechanical properties biocompatibility