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Critical role of carbon support in metal nanoaggregate facilitating Fe-N-C catalyst for PEM fuel cell application

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Journal of Energy Chemistry 2024年第10期97卷 669-676,I0014页

作者： Liming Guo Xin Wan Qingtao Liu Xiaofang Liu Jiaxiang shang Ronghai Yu Jianglan Shui School of Materials Science and Engineering Beihang UniversityBeijing 100191China Tianmushan Laboratory Hangzhou 310023ZhejiangChina

Metal nanoaggregates can simultaneously enhance the activity and stability of Fe-N-C catalysts in proton-exchange-membrane fuel cells(PEMFC).Previous studies on the relevant mechanism have focused on the direct interaction between FeN_(4)active sites and metal ***,the role of carbon support that hosts metal nanoaggregates and active sites has been ***,a Fe-N-C catalyst encapsulating inactive gold nanoparticles is prepared as a model catalyst to investigate the electronic tuning of Au nanoparticles(NPs)towards the carbon *** NPs donate electrons to carbon support,making it rich inπelectrons,which reduces the work function and regulates the electronic configuration of the FeN_(4)sites for an enhanced ORR ***,the electron-rich carbon support can mitigate the electron depletion of FeN_(4)sites caused by carbon support oxidation,thereby preserving its high *** yield and accumulation of H_(2)O_(2)are thus alleviated,which delays the oxidation of the catalyst and benefits the *** to the electron-rich carbon support,the composite catalyst achieves a top-level peak power density of 0.74 W/cm^(2) in a 1.5 bar H_(2)-air PEMFC,as well as the improved *** work elucidates the key role of carbon support in the performance enhancement of the FeN-C/metal nanoaggregate composite catalysts for fuel cell application.

关键词： Fuel cells Oxygen reduction reaction Fe-N-C Hetero-structure catalyst Carbon support

Electrocatalysts with atomic-level site for nitrate reduction to ammonia

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Journal of Energy Chemistry 2024年第9期96卷 642-668页

作者： Shuai Yin Rong Cao Yifan Han Jiachangli shang Jing Zhang Wei Jiang Guigao Liu National Special Superfine Powder Engineering Research Center School of Chemistry and Chemical EngineeringNanjing University of Science and TechnologyNanjing 210094JiangsuChina School of Pharmacy Jiangsu UniversityZhenjiang 212013JiangsuChina

Ammonia(NH_(3))is an important raw material for modern agriculture and industry,being widely demanded to sustain the sustainable development of modern ***,the industrial production methods of NH_(3),such as the traditional Haber-Bosch process,have drawbacks including high energy consumption and significant carbon dioxide *** recent years,the electrocatalytic nitrate reduction reaction(NO_(3)RR)powered by intermittent renewable energy sources has gradually become a multidisciplinary research hotspot,as it allows for the efficient synthesis of NH_(3)under mild *** this review,we focus on the research of electrocatalysts with atomic-level site,which have attracted attention due to their extremely high atomic utilization efficiency and unique structural characteristics in the field of NO_(3)***,we introduce the mechanism of nitrate reduction for ammonia synthesis and discuss the in-situ characterization techniques related to the mechanism ***,we review the progress of the electrocatalysts with atomic-level site for nitrate reduction and explore the structure-activity relationship to guide the rational design of efficient ***,the conclusions of this review and the challenges and prospective of this promising field are presented.

关键词： Ammonia synthesis Nitrate reduction Electrocatalysts with atomic-level site Reaction mechanism In-situ characterization techniques

Asymmetrically coordinated single atom Cu catalyst with unsaturated C-Cu-N structure for CO_(2) reduction to CO

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Nano Research 2024年第5期17卷 3911-3918页

作者： Zheng Liu Yuxuan Liu Jingqiao Zhang Ting Cao Zhiyi Sun Juzhe Liu Huishan shang State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China SEPA Key Laboratory of Eco-Industry Chinese Research Academy of Environmental SciencesBeijing 100012China The Key Laboratory of Resources and Environmental System Optimization Ministry of EducationCollege of Environmental Science and EngineeringNorth China Electric Power UniversityBeijing 102206China School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China

Single atom catalysts(SACs)play a crucial role in energy catalysis due to their distinct coordination environment and high atomic utilization *** study focuses on the synthesis of a monatomic Cu catalyst with Cu-N1C1 coordination anchored to N-doped Ti_(3)C_(2)T_(x) MXene(Cu SA@N-Ti_(3)C_(2)T_(x))to achieve efficient reduction of CO_(2) to *** characterization,including morphology and multispectral analysis,confirmed the uniform distribution of asymmetrically coordinated Cu atoms in unsaturated C-Cu-N bridge fragments on Ti_(3)C_(2)T_(x).The Cu SA@N-Ti_(3)C_(2)T_(x) catalyst exhibited an excellent CO selectivity with Faraday efficiency of 97.4%at-0.58 V *** hydrogen electrode(RHE)and satisfactory *** in situ X-ray absorption fine structure(XAFS)results confirmed that the carbon dioxide reduction reaction(CO_(2)RR)product distribution is mainly affected by potential-dependent valence change of Cu *** findings highlight the extensive potential of tuning coordination structure of MXene-based single-atom catalysts for CO_(2) reduction reactions.

关键词： cooper single atom atomic regulation MXene Ti_(3)C_(2)T_(x) CO_(2)reduction

A review of microwave-metal discharge interaction:Mechanism,regulation,and application for synthesis of nanomaterials

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Nano Research 2024年第10期17卷 9225-9254页

作者： Yixuan Xie Ruiqian Shi Benwei Fu Chengyi Song Wen shang Peng Tao Tao Deng State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National Engineering Research Center of Special Equipment and Power System for Ship and Marine Engineering Shanghai 200030China

Placing metals within microwave ovens has been generally viewed as a dangerous practice because of occurrence of violent discharge,but in recent years such discharge phenomenon has attracted increasing attention and has enabled a variety of exciting *** this work,we provide a comprehensive review of fundamental understanding of microwave-metal discharge interaction and its state-of-the-art application for nanomaterials *** introduce the microscopic interaction between different categories of materials and the electric and magnetic field of *** microwave-metal interaction,we highlight its size-dependence and point out the influence of the oxide layer on the surface of *** discuss the required conditions for occurrence of discharge,microscopic formation mechanism,and characteristic features of microwave-metal discharge *** analyzing the influence from the microwave input,discharging metals,and surrounding discharging media,we discuss the strategy for systematical regulation of the discharge *** describe the applications of the microwave-metal discharge for facile synthesis of various functional nanomaterials including core-shell carbon/metal,metal oxides,metal chalcogenides,intermetallic compounds,metallic nanoparticles and metallic compounds,and organic ***,the challenges in precise characterization and dynamic regulation of the discharge process as well as exciting application opportunities are discussed.

关键词： microwave-metal interaction discharge microwave heating skin depth nanomaterial synthesis

Taiji-TianQin-LISA network:Precisely measuring the Hubble constant using both bright and dark sirens

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 59-77页

作者： shang-Jie Jin Ye-Zhu Zhang Ji-Yu Song Jing-Fei Zhang Xin Zhang Key Laboratory of Cosmology and Astrophysics(Liaoning)&College of Sciences Northeastern UniversityShenyang 110819China Key Laboratory of Data Analytics and Optimization for Smart Industry(Ministry of Education) Northeastern UniversityShenyang 110819China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern UniversityShenyang 110819China

In the coming decades,the space-based gravitational-wave(GW)detectors such as Taiji,TianQin,and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole binaries(MBHBs).In this work,we investigate the potential of GW standard sirens from the Taiji-TianQin-LISA network in constraining cosmological *** the optimistic scenario in which electromagnetic(EM)counterparts can be detected,we predict the number of detectable bright sirens based on three different MBHB population models,i.e.,popⅢ,Q3d,and *** results show that the TaijiTianQin-LISA network alone could achieve a constraint precision of 0.9%for the Hubble constant,meeting the standard of precision ***,the Taiji-TianQin-LISA network could effectively break the cosmological parameter degeneracies generated by the CMB data,particularly in the dynamical dark energy *** combined with the CMB data,the joint CMB+Taiji-TianQin-LISA data offerσ(w)=0.036 in the wCDM model,which is close to the latest constraint result obtained from the CMB+SN *** also consider a conservative scenario in which EM counterparts are not *** to the precise sky localizations of MBHBs by the Taiji-TianQin-LISA network,the constraint precision of the Hubble constant is expected to reach 1.2%.In conclusion,the GW standard sirens from the Taiji-TianQin-LISA network will play a critical role in helping solve the Hubble tension and shedding light on the nature of dark energy.

关键词： space-based gravitational wave detection standard sirens the Taiji-TianQin-LISA network the Hubble constant dark energy

Porous nanocomposites with enhanced intrinsic piezoresistive sensitivity for bioinspired multimodal tactile sensors

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Microsystems & Nanoengineering 2024年第1期10卷 243-256页

作者： Jianpeng Zhang Song Wei Caichao Liu Chao shang Zhaoqiang He Yu Duan Zhengchun Peng State Key Laboratory of Radio Frequency Heterogeneous Integration(Shenzhen University) School of Physics and Optoelectronic EngineeringShenzhen University518060 ShenzhenGuangdong ProvinceP.R.China Linksense Technology Ltd. 518060 ShenzhenGuangdong ProvinceP.R.China

In this work,we propose porous fluororubber/thermoplastic urethane nanocomposites(PFTNs)and explore their intrinsic piezoresistive sensitivity to *** experiments reveal that the intrinsic sensitivity of the PFTN-based sensor to pressure up to 10 kPa increases up to 900%compared to the porous thermoplastic urethane nanocomposite(PTN)counterpart and up to 275%compared to the porous fluororubber nanocomposite(PFN)*** pressures exceeding 10 kPa,the resistance-pressure relationship of PFTN follows a logarithmic function,and the sensitivity is 221%and 125%higher than that of PTN and PFN,*** the excellent intrinsic sensitivity of the thick PFTN film,a single sensing unit with integrated electrode design can imitate human skin for touch detection,pressure perception and traction *** sensing range of our multimodal tactile sensor reaches~150 Pa,and it exhibits a linear fit over 97%for both normal pressure and shear *** also demonstrate that an electronic skin,made of an array of sensing units,is capable of accurately recognizing complex tactile interactions including pinch,spread,and tweak motions.

关键词： sensation intrinsic modal

A Railway Fastener Inspection Method Based on Abnormal Sample Generation

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 565-592页

作者： Shubin Zheng Yue Wang Liming Li Xieqi Chen Lele Peng Zhanhao shang Higher Vocational and Technical College Shanghai University of Engineering ScienceShanghai200437China School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai201620China shanghai Engineering Research Centre of Vibration and Noise Control Technologies for Rail Transit Shanghai University of Engineering ScienceShanghai201620China

Regular fastener detection is necessary to ensure the safety of ***,the number of abnormal fasteners is significantly lower than the number of normal fasteners in real *** supervised inspectionmethods have insufficient detection ability in cases of imbalanced *** solve this problem,we propose an approach based on deep convolutional neural networks(DCNNs),which consists of three stages:fastener localization,abnormal fastener sample generation based on saliency detection,and fastener state ***,a lightweight YOLOv5s is designed to achieve fast and precise localization of fastener ***,the foreground clip region of a fastener image is extracted by the designed fastener saliency detection network(F-SDNet),combined with data augmentation to generate a large number of abnormal fastener samples and balance the number of abnormal and normal ***,a fastener inspection model called Fastener ResNet-8 is constructed by being trained with the augmented fastener *** show the effectiveness of our proposed method in solving the problem of sample imbalance in fastener *** and quantitative comparisons show that the proposed F-SDNet outperforms other state-of-the-art methods in clip region extraction,reaching MAE and max F-measure of 0.0215 and 0.9635,*** addition,the FPS of the fastener state inspection model reached 86.2,and the average accuracy reached 98.7%on 614 augmented fastener test sets and 99.9%on 7505 real fastener datasets.

关键词： Railway fastener sample generation inspection model deep learning

Federated learning-outcome prediction with multi-layer privacy protection

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Frontiers of Computer Science 2024年第6期18卷 186604-186604页

作者： ZHANG Yupei LI Yuxin WANG Yifei WEI Shuangshuang XU Yunan shang Xuequn School of Computer Science Northwestern Polytechnical University MIIT Lab of Big Data Storage and Management

Learning-outcome prediction (LOP) is a long-standing and critical problem in educational routes. Many studies have contributed to developing effective models while often suffering from data shortage and low generalization to various institutions due to the privacy-protection issue. To this end, this study proposes a distributed grade prediction model, dubbed FecMap, by exploiting the federated learning (FL) framework that preserves the private data of local clients and communicates with others through a global generalized model. FecMap considers local subspace learning (LSL), which explicitly learns the local features against the global features, and multi-layer privacy protection (MPP), which hierarchically protects the private features, including model-shareable features and not-allowably shared features, to achieve client-specific classifiers of high performance on LOP per institution. FecMap is then achieved in an iteration manner with all datasets distributed on clients by training a local neural network composed of a global part, a local part, and a classification head in clients and averaging the global parts from clients on the server. To evaluate the FecMap model, we collected three higher-educational datasets of student academic records from engineering majors. Experiment results manifest that FecMap benefits from the proposed LSL and MPP and achieves steady performance on the task of LOP, compared with the state-of-the-art models. This study makes a fresh attempt at the use of federated learning in the learning-analytical task, potentially paving the way to facilitating personalized education with privacy protection.

关键词： federated learning local subspace learning hierarchical privacy protection learning outcome prediction privacy-protected representation learning

Improving hydrogen storage thermodynamics and kinetics of Ce-Mg-Ni-based alloy by mechanical milling with TiF_(3)

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Journal of Magnesium and Alloys 2024年第4期12卷 1593-1607页

作者： Hongwei shang Wei Zhang Xin Wei Yaqin Li Zeming Yuan Jun Li Yanghuan Zhang School of Mechanical and Electrical Engineering Chuzhou UniversityChuzhou 239000China Department of Functional Material Research Central Iron and Steel Research InstituteNo.76 Xueyuannan RoadHaidian DistrictBeijing 100081China Key Laboratory of Integrated Exploitation of Bayan-Obo Multi-Metal Resources Inner Mongolia University of Science and TechnologyBaotou 014010China China Rare Earth New Material(Weishan)Co. Ltd.Jining 277600China

Mg-based hydrides are too stable and the kinetics of hydrogen absorption and desorption is not *** efficient way to improve these shortcomings is to employ reactive ball milling to synthesize the nanocomposite materials of Mg and *** this experiment,TiF_(3)was selected as an additive,and the mechanical milling method was employed to prepare the experimental *** alloys used in this experiment were the as-cast Ce_(5)Mg_(85)Ni_(10),as-milled Ce_(5)Mg_(85)Ni_(10)and Ce_(5)Mg_(85)Ni_(10)+3 wt.%*** phase transformation,structural evolution,isothermal and non-isothermal hydrogenation and dehydrogenation performances of the alloys were inspected by XRD,SEM,TEM,Sievert apparatus,DSC and *** revealed that nanocrystalline appeared in the as-milled *** with the as-cast alloy,ball milling made the particle dimension and grain size decrease dramatically and the defect density increase *** addition of TiF_(3)made the surface of ball milling alloy particles markedly coarser and more *** milling and adding TiF_(3)distinctly improved the activation and kinetics of the ***,ball milling along with TiF_(3)can decrease the onset dehydrogenation temperature of Mg-based hydrides and slightly ameliorate their thermodynamics.

关键词： Mg-based hydrides TiF_(3) Ball milling Thermodynamics Kinetics