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Strong and conductive reduced graphene oxide-MXene porous films for efficient electromagnetic interference shielding

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Nano Research 2022年第6期15卷 4916-4924页

作者： Yu Zhang Ming-Ke Xu zhenguo Wang Tianyu Zhao Liu-Xin Liu Hao-Bin Zhang Zhong-zhen Yu State Key Laboratory of Organic-Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing 100029China

Lightweight,flexible,and electrically conductive porous films are promising for efficient electromagnetic interference(EMI)***,the mechanical and electrical properties of porous films are far from ***,we fabricate mechanically flexible and electrically conductive reduced graphene oxide(rGO)-Ti_(3)C_(2)T_(x)MXene(rG-M)porous films with optimized continuous cellular morphology by a controlled hydrazine foaming *** presence of MXene prevents excessive expansion of the rG-M film,improves the electron conduction paths,and enhances the mechanical *** resultant rG-M porous film has superior mechanical and electric performances compared to its rGO counterpart,giving one of the highest tensile strengths(24.5 MPa)among the porous films,a high electrical conductivity of 74.4 S·cm^(−1),and an excellent broadband EMI shielding from 8 to 26.5 GHz.A high EMI shielding effectiveness of 52.6 dB is achieved for the porous film by adjusting its thickness and treatment procedure,providing a feasible fabrication route for lightweight and high-performance EMI shielding materials.

关键词： graphene MXene electromagnetic interference shielding porous films electrical conductivity

Adsorption behavior of CO_(2)/H_(2)S mixtures in calcite slit nanopores for CO_(2) storage:An insight from molecular perspective

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Petroleum Science 2024年第4期21卷 2444-2456页

作者： Cheng Qian zhen-Hua Rui Yue-Liang Liu Kai Du Chen Liu Yang Zhao Xiao-Min Ma State Key Laboratory of Petroleum Resources and Engineering China University of PetroleumBeijing102249China College of Petroleum Engineering China University of PetroleumBeijing102249China College of Carbon Neutrality Future Technology China University of PetroleumBeijing102249China College of Petroleum China University of Petroleum-Beijing at KaramayKaramay83400XinjiangChina College of Mining Engineering Taiyuan University of TechnologyTaiyuan030024ShanxiChina

It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) *** CO_(2) produced from industrial exhaust contains impurity gases such as H_(2)S that might impact CO_(2) sequestration due to competitive *** study makes a commendable effort to explore the adsorption behavior of CO_(2)/H_(2)S mixtures in calcite slit *** Canonical Monte Carlo(GCMC)simulation is employed to reveal the adsorption of CO_(2),H_(2)S as well as their binary mixtures in calcite *** show that the increase in pressure and temperature can promote and inhibit the adsorption capacity of CO_(2) and H_(2)S in calcite nanopores,***_(2)exhibits stronger adsorption on calcite surface than H_(2)*** energy plays the dominating role in the adsorption *** energy accounts for 97.11%of the CO_(2)-calcite interaction energy and 56.33%of the H_(2)S-calcite interaction energy at 10 MPa and 323.15 *** presence of H_(2)S inhibits the CO_(2) adsorption in calcite nanopores due to competitive adsorption,and a higher mole fraction of H_(2)S leads to less CO_(2) *** quantity of CO_(2) adsorbed is lessened by approximately 33%when the mole fraction of H_(2)S reaches ***_(2) molecules preferentially occupy the regions near the po re wall and H_(2)S molecules tend to reside at the center of nanopore even when the molar ratio of CO_(2) is low,indicating that CO_(2) has an adsorption priority on the calcite surface over H_(2)*** addition,moisture can weaken the adsorption of both CO_(2) and H_(2)S,while CO_(2) is more *** interestingly,we find that pure CO_(2) is more suitable to be sequestrated in the shallower formations,i.e.,500-1500 m,whereas CO_(2)with H_(2)S impurity should be settled in the deeper reservoirs.

关键词： Adsorption behavior CO_(2)/H_(2)S binary mixtures Molecular perspective Calcite slit nanopores CO_(2)sequestration

Luminescence Properties and Crystal Growth of Er/Yb Codoped KGd(WO_4)_2

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Chinese Journal of Structural Chemistry 2005年第8期24卷 879-884页

作者： WANG Yan TU Chao-Yang ZHU Zhao-Jie LI Jian-Fu YOU zhen-Yu WU Bai-Chang State Key Laboratory of Structural Chemistry Fujian Institute of Research on theStructure of Matter The Chinese Academy of Sciences ChinaFuzhou Fujian 350002

In this paper, the spectral and luminescence properties of a series of KGd（WO4）2 powder samples codoped with different concentrations of Er^3＋ and Yb^3＋ were reported,and the best doping concentrations were found to be lat% Er^3＋ and 10at% Yb^3＋ for attaining the strongest intensity. The Er^3＋/yb^3＋ codoped KGd（WO4）2 crystal with good optical quality was grown by the TSSG method and the growth conditions were presented. The unpolarized absorption and emission spectra of the crystal have been measured. The strong absorption peak is at 980 nm with a FWHM of 65 nm, and the emission peak is at 1536 nm when pumped by 976 rim. The fluorescence lifetime of manifold ^4I13/2 is estimated to be 4.5 ms at room *** of Er, Yb：KGW crystal have shown it to have necessary combination of properties to get an effective generation of - 1.54 μm eye-safe radiation with laser diode pumping.

关键词： Er Yb:KGW crystal luminescence properties,crystal growth optical properties

Phase Transition and Elastic Properties of NbN under Hydrostatic Pressure

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Journal of Wuhan University of Technology(Materials Science) 2014年第1期29卷 49-57页

作者：任达华 AN Xinyou 程新路 LUO Xuan YANG Ruizhuang ZAHNG zhen WU Weidong Institute of Atomic and Molecular Physics Sichuan University Reseach Center of Laser Fusion CAEP

First-principles pseudopotential calculations are performed to investigate the phase transition and elastic properties of niobium nitrides （NbN）. The lattice parameters a0 and c0/a0, elastic constants Cu, bulk modulus B0, and the pressure derivative of bulk modulus B0＇ are calculated. The results are in good agreement with numerous experimental and theoretical data. The enthalpy calculations predict that NbN undergoes phase transition from NaCl-type to NiAs-type structure at 13.4 GPa with a volume collapse of about 4.0% and from AsNi-type to CW-type structure at 26.5 GPa with a volume collapse of about 7.0%. Among the four types of structures, CW-type is the most stable structure. The elastic properties are analyzed on the basis of the calculated elastic constants. Isotropic wave velocities and anisotropic elasticity of NbN are studied in detail. The longitudinal and shear-wave velocities, Vr, Vs and V increase with increasing pressure, respectively. The Debye temperature OD increases monotonically with increasing pressure except for NiAs-type structure. Both the longitudinal velocity and the shear-wave velocity increase with pressure for wave vector along all the propagation directions, except for VTA（[100]） and VTA[001]（[110]） with NaCl structure and VTA[001]（[100]） with the other three types of structures.

关键词： phase transition elastic properties isotropic wave velocity anisotropic elasticity NbN

Structural and Photoluminescence Characterization of GaN Film Grown on Si(111)Substrate

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Chinese Physics Letters 1999年第4期16卷 293-294页

作者： YE Zhi-zhen ZHANG Hao-xiang LU Huan-ming ZHAO Bing-hui State Key Laboratory of Silicon Materials Zhejiang UniversityHangzhou 310027

GaN epilayer grown on Si(111)substrate by a novel vacuum reaction method rather than metal organic chemical vapor deposition or molecule beam epitaxy is *** electron micrograph shows that surface of GaN film is flat and crack-free.A pronounced GaN(0002)peak appears in the x-ray diffraction *** full width at half-maximum(FWHM)of the double-crystal x-ray rocking curve for(0002)diffraction from the GaN epilayer is *** photoluminescence spectrum shows that the GaN epilayer emits light at the wavelength of 365nm with an FWHM of 8nm(74.6meV).

关键词： Si(111) GaN vacuum

Advances in electrochemical reduction of carbon dioxide to formate over bismuth-based catalysts

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Rare Metals 2021年第9期40卷 2327-2353页

作者： Yu-Hong Wang Wen-Jun Jiang Wei Yao Zai-Lun Liu Zhe Liu Yong Yang Li-zhen Gao College of Environmental Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University Xi’anXi’an 710072China School of Mechanical Engineering University of Western AustraliaPerth 6009Australia

Selective CO_(2) reduction to formate with highadded value is one of the most technologically and economically feasible pathways to realize electrochemical CO_(2) fixation. Bismuth-based catalysts have the advantages of nontoxicity, low cost, high abundance, as well as excellent stability. In addition, bismuth-based catalysts display excellent selectivity for the electrochemical reduction of CO_(2) to formate in aqueous electrolytes due to high-hydrogen evolution overpotential. Hence, bismuthbased catalysts are by far the most commercially available materials for electrochemical reduction of CO_(2) to *** this review, the electrochemical reduction of CO_(2) to formate over bismuth-based catalysts is elaborated. Firstly,this review describes performance evaluation indexes,evaluation systems and reaction mechanisms of the electrochemical reduction of CO_(2) to formate over bismuthbased catalysts. Subsequently, the research means to reveal the reaction mechanism of electrochemical reduction of CO_(2) to formate over bismuth-based catalysts and the performance improvement strategies of the reaction are described in detail. Finally, the opportunities and challenges in this encouraging field are discussed. We believe that this review will contribute to further development of electrochemical reduction of CO_(2) to formate over bismuthbased catalysts.

关键词： Electrochemical CO_(2)reduction Formate Bismuth-based catalysts Reaction research Performance improvement

Ancient water wells reveal a prolonged drought in the lower Yellow River area about 2800 years ago

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Science Bulletin 2018年第20期63卷 1324-1327页

作者： Shiyong Yu Xuexiang Chen Xiuling Liu zhen Fang Junfeng Guo Senyang Zhan Hui Fang Fahu Chen School of Geography Geomaticsand PlanningJiangsu Normal UniversityXuzhou 221116China Joint International Research Laboratory for Environmental and Social Archaeology 5handong Universityfinan 250100China Jinan Municipal Institute of Archaeology jinan 250062China Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100101China

Proxy records from the North Atlantic realm reveal that large and rapid cooling known as the Bond events continued into the Holocene [1],repeatedly punctuating what is conventionally thought to have been a relatively stable *** that the Holocene is the most recent interglacial period that has spurred the development of modern societies,scrutinizing climate variabil- ity during this period is important not only for predicting the trend of future climate changes,but also for better understanding the driving forces behind the rise and fall of ancient civilizations.

关键词： water wells drought Yellow River area

One-step synthesis of self-healable hydrogels by the spontaneous phase separation of linear multi-block copolymers during the emulsion copolymerization

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Chinese Chemical Letters 2017年第4期28卷 868-874页

作者： Lan-Lan Li Ru-Yi Jiang Jin-Xing Chen Mo-zhen Wang Xue-Wu Ge CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China Petro China Company Limited Beijing 100007China

Self-healable polyacrylamide-based hydrogels were prepared at room temperature via a one-step emulsion copolymerization of acrylamide（AM）,dodecyl 2-methacryIate（DM）,and 5-acetylaminopentyl acrylate（AAPA） using sodium dodecyl sulfonate（SDS） as the emulsifier and ammonium persulfate（APS）as the *** produced linear multi-block copolymer chains are composed of randomly-linked hydrophilic polyacrylamide segments（PAM） and hydrophobic segments constituted by DM and AAPA units（P（DM-co-AAPA））.The P（DM-co-AAPA） segments will self-aggregate into hydrophobic microdomains during the polymerization process driven by the hydrophobic interactions,and finally separate from water phase,acting as the crosslinks and leading to the formation of strong hydrogels with a storage modulus as high as 400 *** hydrophobic microdomains will be dissolved in water when the temperature increases to 70℃,resulting in a temperature-responsive reversible sol-gel transition of the prepared ***,the prepared hydrogels have excellent self-healing *** broken hydrogels can be automatically healed into a body with a same strength within 2-min＇s *** work provides a new simple way to prepare reversible physical crosslinked hydrogel with high strength and self-healing efficiency.

关键词： Self-healing 5-Acetylaminopentyl acrylate Hydrogen bond Emulsion copolymerization

Quantum Mechanical Analysis of Sodium Alginate Effects on the Konjac Glucomannan Stability

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Chinese Journal of Structural Chemistry 2015年第8期34卷 1187-1196页

作者： MA zhen PANG Jie LIN Mei-Ling XIE Bing-Qing CHEN Han CHEN Jing-Ling College of Food Science Fujian Agriculture and Forestry University Department of Physics Jefferson Physical Lab Harvard University Chern Institute of Mathematics Nankai University

Konjac glucomannan （KGM） and sodium alginate were chosen as the research objects, and the hydrogen bond conformation of compound system was studied with the molecular dynamics simulation, which simulated the energy variety in composite process. Combining with Hamiltonian in quantum mechanics calculation, the mechanism of hydrogen bond in KGM and sodium alginate compound system stability was analyzed from a micro angle. The results showed that, the hydrogen bonds occurring between the molecule of KGM and sodium alginate are in large number, and they mainly appeared between the -OH on C（6）, C（3） in the mannose residues of KGM and C（2）, C（3） of sodium alginate. The formation of hydrogen bonds results in the energy expectation value of the Hamiltonian thermal density matrix of the compound system to be negative, the energy of the system to decrease, and the compounds tending to form stable conformations.

关键词： Konjac glucomannan sodium alginate composite molecular dynamics quantum