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Current advances of transition metal dichalcogenides in electromagnetic wave absorption:A brief review

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International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 428-445页

作者： Shijie Zhang Jiying li xiaotian Jin Guanglei Wu School of Material Science and Engineering Henan Province Engineering Research Center of New Cermet Matrix CompositesHenan University of TechnologyZhengzhou 450001China Institute of Materials for Energy and Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China

Transition metal dichalcogenides(TMDs)show great advantages in electromagnetic wave(EMW)absorption due to their unique structure and electrical properties.Tremendous research works on TMD-based EMW absorbers have been conducted in the last three years,and the comprehensive and systematical summary is still a rarity.Therefore,it is of great significance to elaborate on the interaction among the morphologies,structures,phases,components,and EMW absorption performances of TMD-based absorbers.This review is devoted to analyzing TMD-based absorbers from the following perspectives:the EMW absorption regulation strategies of TMDs and the latest progress of TMD-based hybrids as EMW absorbers.The absorption mechanisms and component-performance dependency of these achievements are also summarized.Finally,a straightforward insight into industrial revolution upgrading in this promising field is proposed.

关键词： transition metal dichalcogenides phase manipulation hybrids hierarchical structure absorption mechanism

Facet-dependent activation of oxalic acid over hematite nanocrystals under the irradiation of visible light for efficient degradation of pollutants

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Journal of Environmental Sciences 2024年第8期142卷 204-214页

作者： Zhixiong Yang Yuan li xiaotian Wang Jiaming li Jiquan Wang Gaoke Zhang Hubei Key Laboratory of Mineral Resources Processing and Environment State Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan 430070China Hubei Engineering Consulting Co. Ltd.Wuhan 430071China

Naturally occurring hematite has been widely studied in the Fenton-like system for water pollutant remediation due to its abundance and non-toxicity.However,its inadequate catalytic activity results in difficulty in effectively degrading pollutants in the catalytic degradation system that it constitutes.Thus,we constructed a photochemical system composed of hematite with{001}facet of high activity facet and low-cost and non-toxic oxalic acid(OA)for the removal of various types of pollutants.The removal rate for the degradation of metronidazole,tetracycline hydrochloride,Rhodamine B,and hexavalent chromium by hematite nanoplate with the exposed{001}facet activating OA under visible light irradiation was 4.75,2.25,2.33,and 2.74 times than that by the exposed{110}facet,respectively.Density functional theory(DFT)calculation proved that the OA molecule was more easily adsorbed on the{001}facet of hematite than that on the{110}facet,which would favor the formation of the more Fe(Ⅲ)-OA complex and reactive species.In addition,the reactive site of metronidazole for the attraction of radicals was identified on the basis of the DFT calculation on the molecular occupied orbitals,and the possible degradation pathway for metronidazole included carbon chain fracture,hydroxyethyl-cleavage,denitrogenation,and hydroxylation.Thus,this finding may offer a valuable direction in designing an efficient iron-based catalyst based on facet engineering for the improved activity of Fenton-like systems such as OA activation.

关键词： Hematite Facet exposure Oxalic acid activation Fenton-like system Pollutant removal

Prenatal exposure to perfluorooctane sulfonate and perfluorooctanoate and the risk of preeclampsia: a nested case-control study in Shanghai, China

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Chinese Medical Journal 2023年第7期136卷 857-859页

作者： Ying Zhao Jizi Zhou Huangfang Xu Huanqiang Zhao Ping An Xiaotian Li Yu Xiong Obstetrics and Gynecology Hospital Fudan UniversityShanghai 200090China Shenzhen Maternity&Child Healthcare Hospital ShenzhenGuangdong 518028China

To the Editor:Preeclampsia presents with new-onset hypertension and maternal multi-organ injury that is associated with substantial maternal and fetal morbidity and mortality.[1]Although the etiology remains a mystery,environmental toxicants,especially those that interact with genetic factors and disrupt normal placental function,are emerging as potential risk factors for preeclampsia.

关键词： mortality fetal clamp

A Novel Re-weighted CTC Loss for Data Imbalance in Speech Keyword Spotting

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Chinese Journal of Electronics 2023年第3期32卷 465-473页

作者： LAN xiaotian HE Qianhua YAN Haikang li Yanxiong School of Electronic and Information Engineering South China University of Technology

Speech keyword spotting system is a critical component of human-computer interfaces. And connectionist temporal classifier(CTC) has been proven to be an effective tool for that task. However, the standard training process of speech keyword spotting faces a data imbalance issue where positive samples are usually far less than negative samples. Numerous easy-training negative examples overwhelm the training, resulting in a degenerated model. To deal with it, this paper tries to reshape the standard CTC loss and proposes a novel reweighted CTC loss. It evaluates the sample importance by its number of detection errors during training and automatically down-weights the contribution of easy examples, the majorities of which are negatives, making the training focus on samples deserving more training. The proposed method can alleviate the imbalance naturally and make use of all available data efficiently. Evaluation on several sets of keywords selected from AISHELL-1 and AISHELL-2 achieves 16%–38% relative reductions in false rejection rates over standard CTC loss at 0.5 false alarms per keyword per hour in experiments.

关键词： Speech keyword spotting Connectionist temporal classifier Data imbalance Sample importance re-weighting

Ionic liquid Assisted Imprint for Efficient and Stable Quasi-2D Perovskite Solar Cells with Controlled Phase Distribution

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Nano-Micro Letters 2023年第7期15卷 1-15页

作者： Haibin Peng Dengxue li Zongcai li Zhi Xing xiaotian Hu Ting Hu Yiwang Chen Department of Polymer Materials and Engineering School of Physics and Materials ScienceNanchang University999 Xuefu AvenueNanchang 330031People’s Republic of China College of Chemistry and Chemical Engineering Institute of Polymers and Energy Chemistry(IPEC)Nanchang University999 Xuefu AvenueNanchang 330031People’s Republic of China National Engineering Research Center for Carbohydrate Synthesis/Key Lab of Fluorine and Silicon for Energy Materials and Chemistry of Ministry of EducationJiangxi Normal University99 Ziyang AvenueNanchang 330022People’s Republic of China Peking University Yangtze Delta Institute of Optoelectronics Nantong 226010People’s Republic of China

Although two-dimensional perovskite devices are highly stable,they also lead to a number of challenges.For instance,the introduction of large organic amines makes crystallization process complicated,causing problems such as generally small grain size and blocked charge transfer.In this work,imprint assisted with methylamine acetate were used to improve the morphology of the film,optimize the internal phase distribution,and enhance the charge transfer of the perovskite film.Specifically,imprint promoted the dispersion of spacer cations in the recrystallization process with the assistance of methylamine acetate,thus inhibited the formation of low-n phase induced by the aggregation of spacer cations and facilitated the formation of 3D-like phase.In this case,the corresponding quasi-2D perovskite solar cells delivered improved efficiency and exhibited superior stability.Our work provides an effective strategy to obtain uniform phase distribution for quasi-2D perovskite.

关键词： Imprint Two-dimensional perovskite Phase distribution Charge transfer Stability

Roles of hydroxyl and oxygen vacancy of CeO_(2)·xH_(2)O in Pd-catalyzed ethanol electro-oxidation

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Science China Chemistry 2022年第5期65卷 877-884页

作者： Zhenyu li Jiefei li Zexuan Zheng Kunhong Jiang Tianrun Zheng Dongmin Wang Hang Wei Zhiming Shi Xiaotian Li Haibin Chu College of Chemistry and Chemical Engineering Inner Mongolia Engineering and Technology Research Center for Catalytic Conversion and Utilization of Carbon Resource MoleculesInner Mongolia UniversityHohhot 010021China College of Materials Science and Engineering Jilin UniversityChangchun 130022China College of Chemistry Jilin UniversityChangchun 130012China State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

In the field of noble metal-catalyzed alcohol electro-oxidation reaction(AOR),huge attention is paid on the composition,size,facet,and structure of the metals,while the support engineering should also be emphasized.CeO_(2)has been widely used as a unique support in AOR,primarily due to its abundant oxygen vacancies(O_(v)).Herein,we report CeO_(2)·xH_(2)O nanoparticles with both massive hydroxyl groups(OH)and O_(v)remarkably enhance the catalytic activity and stability of Pd toward ethanol oxidation reaction(EOR).The CO striping experiments and density functional theory(DFT)calculations suggest that OH and O_(v)on CeO_(2)·xH_(2)O surface bring about a large downshift of Pd d-band center and a significant weakening of CO absorption on Pd.Moreover,OH and O_(v)also play synergic roles in the removal of toxic intermediates.Consequently,the important roles of OH and O_(v)of CeO_(2)·xH_(2)O are confirmed in Pd-catalyzed EOR.The facile CeO_(2)·xH_(2)O-enhanced strategy can contribute to the catalyst design for other energy conversion reactions.

关键词： electrocatalysis ceria hydroxyl oxygen vacancy ethanol oxidation reaction

A novel Cu_(1.5)Mn_(1.5)O_(4)photothermal catalyst with boosted surface lattice oxygen activation for efficiently photothermal mineralization of toluene

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Nano Research 2023年第2期16卷 2133-2141页

作者： Qiang Cheng Zhuangzhuang Wang xiaotian Wang Jiaming li Yuan li Gaoke Zhang Shenzhen Research Institute Hubei Key Laboratory of Mineral Resources Processing and EnvironmentState Key Laboratory of Silicate Materials for ArchitecturesWuhan University of TechnologyWuhan 430070China

Developing a novel photothermal catalyst for efficient mineralization of volatile organic compounds(VOCs)is of great significance to control air pollution.Herein,for the first-time,a spinel Cu_(1.5)Mn_(1.5)O_(4)nanomaterial with enhanced surface lattice oxygen activation was successfully obtained by a novel light-driven in situ reconstruction strategy from its precursor(CuMnO_(2))for efficient toluene mineralization.X-ray diffraction(XRD)and high-resolution transmission electron microscopy(HRTEM)analyses confirm that the CuMnO_(2)phase was converted into spinel Cu1.5Mn1.5O4 phase under full spectrum light irradiation.Ultraviolet–visible–near infrared ray(UV–vis–NIR)spectroscopy,X-ray photoelectron spectroscopy(XPS)analysis,and density functional theory(DFT)calculations determine that the strong near-infrared absorption ability and low dissociation energy of oxygen bond in Cu_(1.5)Mn_(1.5)O_(4)are beneficial to its surface lattice oxygen activation.Furthermore,O2-temperature programmed desorption(TPD)and in situ diffuse reflectance infrared transform spectroscopy(DRIFTS)further indicate that the surface lattice oxygen of the Cu_(1.5)Mn_(1.5)O_(4)is easily activated under light irradiation,which can promote ring opening of toluene.This research endows a new design of photothermal nanomaterial with enhanced lattice oxygen activation for deep oxidation of VOCs.

关键词： Cu_(1.5)Mn_(1.5)O_(4)nanomaterial surface lattice oxygen light-driven photothermal catalysis volatile organic compounds

Consistent nighttime light time series in 1992–2020 in Northern Africa by combining DMSP-OLS and NPP-VIIRS data

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Big Earth Data 2022年第4期6卷 603-632页

作者： xiaotian Yuan li Jia Massimo Menenti Min Jiang State Key Laboratory of Remote Sensing Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Department of Geoscience and Remote Sensing Delft University of TechnologyDelftThe Netherlands

Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely populated and data-poor regions such as Northern Africa.The intensity and spatial distribution of nighttime lights provide useful information on human activities and can be observed by space-borne imaging radiometers.Our study helps to bridge the gap between the DMSP-OLS data available until 2013 and the NPP-VIIRS data available since 2013.The approach to calibrate the OLS data includes three steps:a)inter-calibrate the OLS DN data acquired by different sensors in 1992-2013;b)cali-brate the OLS DN data using VIIRS data in 2013;c)generate syn-thetic OLS radiance data by degrading the VIIRS data in 2013-2020.We generated a)a time series of calibrated OLS nighttime light radiance data(1992-2013);b)mean annual VIIRS radiance on stable lights at the OLS spatial resolution for 2013-2020;c)synthetic OLS radiance data generated using VIIRS radiance data degraded to match the radiometric specifications of OLS for 2013-2020.The evaluation of these data products in 2013 documented their accu-racy and consistency.

关键词： Nighttime light time series DMSP-OLS NPP-VIIRS median calibration model human activity northern equatorial Africa Sahel

Magnetic-field-driven switchable adhesion of NdFeB/PDMS composite with gecko-like surface

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Nano Research 2023年第5期16卷 6840-6848页

作者： xiaotian Shi Lei Yang Sheng li Yanjie Guo Zhibin Zhao Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong UniversityXi'an 710049China

Switchable adhesives have attracted widespread attention due to their strong reusability and adaptability to operate stably in complex environments.However,the simple fabrication of adhesive structures and reliable control of adhesion remain challenging.Here,we developed a neodymium iron boron/polydimethylsiloxane(NdFeB/PDMS)magnetic composite with optimal mechanical and magnetic performance.Then we fabricated lamellar structures and setal arrays using a molding and magnetic field-induced process,imitating the multi-level adhesion system of gecko feet.The lamellar can be deformed under the action of a magnetic field to control the adhesion,the setal array is used to enhance adhesion and provide self-cleanability to the adhering surface.Switchable adhesion was realized by applying an external magnetic field,where the maximum adhesion strength was 5.1 kPa,the switchable range was within 40%.Through finite element analysis simulations and experimental verification,it was proved that the adhesion force variation was ascribed to the magnetic field-induced surface deformation.Finally,we installed the adhesive on the end of the robotic arm,realizing the transfer of the target object.This work provides a simple method to fabricate a gecko-like surface and a practical strategy to realize switchable adhesion,which sheds light on broad application potential in production lines,medical products,more.

关键词： switchable adhesives dry adhesion gecko bionics magnetic field