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Numerical study of flow and thermal characteristics of pulsed impinging jet on a dimpled surface

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 106-117页

作者： Amin Bagheri Kazem Esmailpour Morteza Heydari Renewable energy Research center Damavand BranchIslamic Azad UniversityDamavandIran

This research comprehensively investigates the flow and thermal characteristics of a pulsating impinging jet over a dimpled surface.It analyzes the impact of key parameters(e.g.,inlet velocity pulsation functions,pulsation frequency,amplitude,dimple pitch,dimple depth,Reynolds number)on flow patterns and heat transfer.Validated computational fluid dynamics and the Re-normalization group turbulence model are employed to accurately simulate complex turbulent flow behavior.Local and average heat transfer coefficients are calculated and compared to steady impingement cases,revealing the potential benefits of pulsation for heat transfer enhancement.The study also examines how pulsation-induced flow modulation and thermal mixing affect heat transfer mechanisms.Results indicate that combining fluctuating flow with a dimpled surface can improve heat transfer rates.In summary,increasing pulsation amplitude consistently enhances heat transfer,while the effect of frequency varies between impinging and wall jet zones.

关键词： Pulsating impinging jet Dimpled surface Heat transfer enhancement Pulsation frequency and amplitude Coherent structures

Electronegativity-assisted optimized electronic structure of functionalized-Pt catalysts for boosting oxygen reduction kinetics

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Rare Metals 2024年第5期43卷 1965-1976页

作者： Jin Long Kai-Wen Zhuang Wei Liao Yan An Bin Wang Chen-Zhong Wu Jian-Xin Cao Qing Wang Jun-Song Chen Qing-Mei Wang Guizhou University Key Laboratory of Green Chemical and Clean energy Technology School of Chemistry and Chemical Engineering Guizhou University Guizhou University Engineering Research center of Efficient Utilization for Industrial Waste Guizhou University Institute of Dual-Carbon and New energy Technology Innovation and Development of Guizhou Province Department of Dermatology West China Hospital Sichuan University Institute for catalysis Hokkaido University School of Materials and energy University of Electronic Science and Technology of China Interdisciplinary Materials Research center Institute for Advanced Study Chengdu University

Opportunity to harmonize aspects of oxygen reduction reaction(ORR) performance and structure, and morphology, as well as composition, is urgent for the commercialization of proton exchange membrane fuel cells. Herein, we demonstrate the design and synthesis of a functionalized-supported-Pt catalyst(Pt@HNC) featuring a hollow nitrogen-modified dodecahedral carbon substrate obtained by a stress-induced-shrink tailoring route. The asobtained Pt@HNC catalyst possesses enhanced ORR performance, in particular with half-wave potential, mass activity(MA) and specific activity, which greatly exceed the commercial Pt/C. The density functional theory(DFT)calculations further confirmed that the charge redistribution induced by the electronegativity differences improved the electron interaction between Pt and HNC support. The optimized electronic structure of Pt weakens the reaction energy barrier on the Pt@HNC surface and adsorption of*OH species, thus cooperatively improving the intrinsic activity toward ORR. Additionally, our work indeed provides a guide for the future design of functional nanomaterials in the field of catalysts and clean energy.

关键词： Proton exchange membrane fuel cell (PEMFC) Oxygen reduction catalysis Supported Pt-based catalyst Stability

Constructing energetic covalent organic frameworks with high stability and low sensitivity

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Chinese Chemical Letters 2024年第3期35卷 544-548页

作者： Hui-Min Guo Xiao-Yu Dong Shan Wang Qian-You Wang Shuang-Quan Zang Henan Key Laboratory of Crystalline Molecular Functional Materials Green Catalysis Centerand College of ChemistryZhengzhou UniversityZhengzhou 450001China

Developing new functional explosives that display high stability,good energy performance,and low sensitivity are one of the key directions of energetic materials research.In this work,two-dimensional(2D)Schiff-based energetic covalent organic frameworks(COFs)are prepared based on triaminoguanidine salts with different anions as building blocks.Benefiting from the robust covalent bond in 2D extended polygons and strongπ-πinteractions in the eclipsed interlayers,the synthesized energetic COFs showed higher thermal stability and lower mechanical sensitivity than their precursor salts.More importantly,incorporating triaminoguanidine salts into COFs effectively increase the corrosion resistance to metal under high humidity conditions,which is due to the imine moieties in COFs functioning asπacceptors and offering strong bonding with metallic ions.This work provides a new pathway for the development of high-performance energetic materials.

关键词： Covalent organic frameworks Energetic materials High thermal stability Low sensitivity Corrosion resistance

Enhancing MXene-based supercapacitors:Role of synthesis and 3D architectures

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Journal of energy Chemistry 2024年第4期91卷 1-26页

作者： Wen Siong Poh Wen Jie Yiang Wee-Jun Ong Pau Loke Show Chuan Yi Foo School of energy and Chemical Engineering Xiamen University MalaysiaSelangor Darul EhsanMalaysia&College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Kelip-kelip!center of Excellence for Light Enabling Technologies Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia center of Excellence for NaNo energy&catalysis Technology(CONNECT) Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia Department of Chemical Engineering Khalifa UniversityShakhbout Bin Sultan St-Zone 1Abu DhabiUnited Arab Emirates Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection Wenzhou UniversityWenzhou 325035ZhejiangChina Department of Chemical and Environmental Engineering Faculty of Science and EngineeringUniversity of Nottingham MalaysiaJalan Broga43500 SemenyihSelangor Darul EhsanMalaysia Department of Sustainable Engineering Saveetha School of EngineeringSIMATSChennai 602105India

MXene has been the limelight for studies on electrode active materials,aiming at developing supercapacitors with boosted energy density to meet the emerging influx of wearable and portable electronic devices.Despite its various desirable properties including intrinsic flexibility,high specific surface area,excellent metallic conductivity and unique abundance of surface functionalities,its full potential for electrochemical performance is hindered by the notorious restacking phenomenon of MXene nanosheets.Ascribed to its two-dimensional(2D)nature and surface functional groups,inevitable Van der Waals interactions drive the agglomeration of nanosheets,ultimately reducing the exposure of electrochemically active sites to the electrolyte,as well as severely lengthening electrolyte ion transport pathways.As a result,energy and power density deteriorate,limiting the application versatility of MXene-based supercapacitors.Constructing 3D architectures using 2D nanosheets presents as a straightforward yet ingenious approach to mitigate the fatal flaws of MXene.However,the sheer number of distinct methodologies reported,thus far,calls for a systematic review that unravels the rationale behind such 3D MXene structural designs.Herein,this review aims to serve this purpose while also scrutinizing the structure–property relationship to correlate such structural modifications to their ensuing electrochemical performance enhancements.Besides,the physicochemical properties of MXene play fundamental roles in determining the effective charge storage capabilities of 3D MXene-based electrodes.This largely depends on different MXene synthesis techniques and synthesis condition variations,hence,elucidated in this review as well.Lastly,the challenges and perspectives for achieving viable commercialization of MXene-based supercapacitor electrodes are highlighted.

关键词： MXene 3D architectures Synthesis design Supercapacitor energy storage

Delving into the dissimilarities in electrochemical performance and underlying mechanisms for sodium and potassium ion storage in N-doped carbon-encapsulated metallic Cu2Se nanocubes

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Journal of energy Chemistry 2024年第8期95卷 336-347页

作者： Xinyu Wang Yanan Xu Xiaofeng Liu Lei Tan Huaiqiang Gu Xin Du Dan Li College of Chemistry Zhengzhou University Green catalysis center College of Chemistry Zhengzhou University Institute of Theoretical Physics Lanzhou University School of Nuclear Science and Technology Lanzhou University Key Laboratory of Advanced energy Materials Chemistry(Ministry of Education) College of Chemistry Nankai University State Key Laboratory of Chemistry and Utilization of Carbon Based energy Resources College of Chemistry Xinjiang University

The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical performance.Herein,metallic Cu2Se encapsulated with N-doped carbon（Cu2Se@NC） was prepared using Cu2O nanocubes as templates through a combination of dopamine polymerization and hightemperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu2Se@NC with excellent electrochemical performance in sodium ion batteries（SIBs） and potassium ion batteries（PIBs）.The composite exhibited excellent rate performance(187.7 mA h g-1at 50 A g-1in SIBs and 179.4 mA h g-1at 5 A g-1in PIBs) and cyclic stability(246,8 mA h g-1at 10 A g-1in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction（XRD） and ex situ transmission electron microscope（TEM）.In particular,the final products in PIBs of K2Se and K2Se3species were determined after discharging,which is different from that in SIBs with the final species of Na2Se.The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu2Se,leading to the introduction of built-in electric field on heterojunction to improve electron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.

关键词： Cu2Se nanocubes DFT calculations Ion storage mechanism Potassium ion batteries Sodium ion batteries

Feasibility of low-intensity ultrasound treatment with hydroxylamine to accelerate the initiation of partial nitrification and allow operation under intermittent aeration

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Journal of Environmental Sciences 2024年第5期139卷 446-459页

作者： Jianxiong Jian Xiaojian Liao Zhihua Mo Shoupeng Li Lei Li Shaojin Chen Zhenhua Huang Junhao Chen Wencan Dai Shuiyu Sun Guangzhou Key Laboratory Environmental catalysis and Pollution Control Guangdong Key Laboratory of Environmental Catalysis and Health Risk ControlSchool of Environmental Science and EngineeringInstitute of Environmental Health and Pollution ControlGuangdong University of TechnologyGuangzhou 510006China Guangdong Province Solid Waste Recycling and Heavy Metal Pollution Control Engineering Technology Research center Guangdong Polytechnic of Environmental Protection EngineeringFoshan 528216China Analysis and Test center Guangdong University of TechnologyGuangzhou 510006China

Partial nitrification is a key aspect of efficient nitrogen removal,although practically it suf-fers from long start-up cycles and unstable long-term operational performance.To address these drawbacks,this study investigated the effect of low intensity ultrasound treatment combined with hydroxylamine(NH2OH)on the performance of partial nitrification.Results showthat compared with the control group,low-intensity ultrasound treatment(0.10W/mL,15 min)combined with NH2OH(5 mg/L)reduced the time required for partial nitrification initiation by 6 days,increasing the nitrite accumulation rate(NAR)and ammonia nitro-gen removal rate(NRR)by 20.4% and 6.7%,respectively,achieving 96.48% NRR.Mechanis-tic analysis showed that NH2OH enhanced ammonia oxidation,inhibited nitrite-oxidizing bacteria(NOB)activity and shortened the time required for partial nitrification initiation.Furthermore,ultrasonication combined with NH2OH dosing stimulated EPS(extracellular polymeric substances)secretion,increased carbonyl,hydroxyl and amine functional group abundances and enhanced mass transfer.In addition,16S rRNA gene sequencing results showed that ultrasonication-sensitive Nitrospira disappeared from the ultrasound+NH_(2)OH system,while Nitrosomonas gradually became the dominant group.Collectively,the results of this study provide valuable insight into the enhancement of partial nitrification start-up during the process of wastewater nitrogen removal.

关键词： Partial nitrification Low-intensity ultrasound Hydroxylamine Ammonia oxidizing bacteria Nitrite oxidizing bacteria

Study on the fast elimination of smoke particle based on electro-acoustic coupling agglomeration technology

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Particuology 2024年第5期88卷 1-10页

作者： Jie Feng Mingfeng Lu Kaige Wang Kun Luo Mingzhou Yu Guangxue Zhang Jiangrong Xu Shuping Pan Hailin Gu The Institute for energy Engineering China Jiliang UniversityHangzhou310018China State Key Laboratory of Clean energy Utilization Zhejiang UniversityHangzhou310027China Qingshanhu energy Research center Zhejiang UniversityHangzhou310017China Zhejiang Ecological Environment Monitoring center Hangzhou310012China

Fire smoke,which consists large amounts of fine particles,is considered as the fatal factor in fires.In this study,a fast smoke particle elimination method based on electro-acoustic coupling agglomeration technology is proposed.First,the experimental results show that the electro-acoustic coupling agglomeration has higher smoke elimination efficiency compared to single-field.The smoke transmission is much less than 80%after 30s of single acoustic or electric field action,while the coupled field reaches 90%.Then,the effects of acoustic frequency,sound pressure level and voltage on the smoke elimination characteristics are discussed.It is found that the optimal acoustic frequency is 1.5kHz.While as the sound pressure level and voltage increase,the elimination efficiency first increases and then tends to stabilize,the critical values of the sound pressure level and voltage are 135 dB and 7kV.This indicates that there is an optimal combination of the three variables.Finally,through the theoretical analysis of particle movement and the micro-morphology of agglomerates,the particle agglomeration mechanism under the electro-acoustic coupling is analyzed.This study provides a new idea for the fast elimination of fire smoke particle.

关键词： Smoke particle Agglomeration Electro-acoustic coupling Smoke elimination

Photo-induced 1,2-aryl migration of 2-chloro-1-arylpropanone under batch and flow conditions:Rapid,scalable and sustainable approach to 2-arylpropionic acids

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Chinese Chemical Letters 2024年第2期35卷 366-369页

作者： Qiao Li Minjie Liu Meifen Jiang Li Wan Yingtang Ning Fen-Er Chen College of Chemical Engineering Zhejiang University of TechnologyHangzhou 310014China Engineering center of catalysis and Synthesis for Chiral Molecules Fudan UniversityShanghai 200433China Shanghai Engineering center of Industrial catalysis for Chiral Drugs Shanghai 200433China Institute of Pharmaceutical Science and Technology Zhejiang University of TechnologyHangzhou 310014China

We report the photo-mediated 1,2-aryl migration of 2‑chloro-1-arylpropanones to 2-arylpropionic acids using HCOONa as an acid scavenger.This pragmatically focused study obviates the multiple-step sequence in the industrially employed,ZnO-promoted rearrangement strategy,and offers rapid access to various 2-arylpropionic acids under environmentally friendly conditions.Furthermore,the successful transfer of this batch photochemistry to a continuous flow platform led to improved scalability and enabled the gram-scale synthesis of loxoprofen.

关键词： Green chemistry Flow chemistry 2-Arylpropionic acids Photo-Favorskii reaction

Construction of a Metallacyclopentadiene Ring through the Attack of Carbanions to M≡C Bond Followed by C—H Activation

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Chinese Journal of Chemistry 2024年第3期42卷 235-242页

作者： Chun Tang Shengjie Zhang Zhengyu Lu Qian Li Ming Luo Dafa Chen Haiping Xia State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringCollaborative Innovation Center of Chemistry for Energy MaterialsXiamen UniversityXiamenFujian361005 China Shenzhen Grubbs Institute and Guangdong Provincial Key Laboratory of catalysis Department of ChemistrySouthern University of Science and TechnologyShenzhenGuangdong518055 China

Metallacyclopentadienes are important metallacycles and regarded as intermediates in many reactions,therefore,new methods to achieve them are anticipated.In this study,a formal[3+2]method,through the reactions of an osmapentalyne with benzyl carbanions,was developed.The reactions underwent a nucleophilic attack of carbanions to the Os≡C bond,followed by C—H activation to form the five-membered osmacyclopentadiene ring.Most of the reactions were carried out at room temperature,the substituents on the aromatic rings of benzyl carbanions are diverse,and the resulting products contain an Os—H bond,representing a novel type of 10C-carbolong complexes.This work provides a new convenient route to construct metallacyclopentadienes,which is expected to further promote the development of such a type of substances.

关键词： Metallacyclopentadiene Carbolong chemistry Osmium C–H activation Nucleophilic addition