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Simulation of ^(13)C NMR chemical shifts of carbinol carbon atoms using quantitative structure-spectrum relationships 被引量:2
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作者 戴益民 黄可龙 +3 位作者 李浔 曹忠 朱志平 杨道武 《Journal of Central South University》 SCIE EI CAS 2011年第2期323-330,共8页
A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear reg... A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method. 展开更多
关键词 carbinol carbon atom ^13C nuclear magnetic resonance chemical shift topological indices quantitative structure-spectroscopy relationship
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Enrichment characteristic of carbon atoms in solid-liquid zone of high carbon steel under different directional solidification rates
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作者 Yong Wan Shan Gao +3 位作者 Meng-hua Li Li-qiang Zhang Yong-hong Wen Ming-ming Song 《China Foundry》 SCIE CAS 2021年第5期488-496,共9页
To reveal the formation mechanism and main influencing factors of C-segregation in high carbon steel under different solidification rates(40,80,160,200 and 320μm·s^(-1)),the enrichment characteristics of carbon ... To reveal the formation mechanism and main influencing factors of C-segregation in high carbon steel under different solidification rates(40,80,160,200 and 320μm·s^(-1)),the enrichment characteristics of carbon atoms in the solid-liquid zone of Fe-0.61%C steel were studied using a zone melting liquid metal cooling apparatus and electron probe microanalysis.The relationships among micro-segregation of carbon atoms,solid-liquid interface morphology and solidification rate were fully discussed.The results show that large dendrite spacing and a slow-moving dendritic interface create less resistance and more time for the migration of interdendritic carbon atoms to liquid zone.This results in the continuous enrichment of carbon atoms in liquid zone,further expands the solid-liquid temperature range,prolongs the solidification time of molten steel,and causes the formation of carbon micro-segregation at the solidification end as the solidification rate is 40μm·s^(-1).Conversely,abundant and elongated secondary dendrite arms with small spacing seriously impede the diffusion of interdendritic carbon-rich molten steel to liquid zone.As a result,there is only obvious dendrite segregation,but little difference in the carbon content along the solidification direction as solidification rate exceeds 200μm·s^(-1). 展开更多
关键词 enrichment characteristic high carbon steel solid-liquid zone carbon atom DENDRITE solidification rate
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Branched alkanes with quaternary carbon atoms in Chinese soils: Potential environmental implications 被引量:6
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作者 BAI Yan FANG Xiaomin +3 位作者 WANG Yongli Fabien Kenig CHEN Xiuling WANG Youxiao 《Chinese Science Bulletin》 SCIE EI CAS 2006年第9期1115-1122,共8页
Lipids extracted from 26 modern soils collected from different climate zones in China and Mongolia are analyzed using gas chromatography- mass spectrometry. These extracts contain pseudo- homologous families of 5,5-di... Lipids extracted from 26 modern soils collected from different climate zones in China and Mongolia are analyzed using gas chromatography- mass spectrometry. These extracts contain pseudo- homologous families of 5,5-diethylalkanes (5,5- DEAs), 6,6-diethylalkanes, 5-butyl-5-ethylalkanes and 6-butyl-6-ethylalkanes, which are first detected in modern soils. All these pseudohomologous series display exclusively odd or exclusively even carbon numbers, clearly indicating a biosynthetic origin, and their carbon number distributions generally covary. The distributions of 5,5-DEAs exhibit strong regional variations, correlated with the spatial distributions of climate and vegetation. The lower molecular weight 5,5-DEAs, maximizing at C21 or C23, dominate in southeast and southwest China samples, while the higher molecular weight 5,5-DEAs with a mode at C29 dominate in cold, arid northwest China and Mongolia. The results demonstrate that the distribution of 5,5-DEAs can serve as a new independent proxy, indicating variations in soil ecosystems and climates, just like the well-known proxy of n-C15—21/n-C22—33 ratios. 展开更多
关键词 烷烃 BAQCs 脂类 土壤 环境影响
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Photochemical naphthylation at(α-carbon atom of carbonyl and its equivalences
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作者 WU,Bi-Qi ZENG,Fan-Wen +2 位作者 LI,Wei ZHAO,Yong WU,Guo-Sheng Shanghai Institute of Organic Chemistry,The Chinese Academy of Sciences,Shanghai 200032 《Chinese Journal of Chemistry》 SCIE CAS CSCD 1992年第1期73-81,共0页
The photostimulated reaction of halonaphthalene with a series of carbanions derived from, propionic acid derivatives in liquid ammonia led to the naphthylation at a-carbon of the carbanions in an isolated yield rangin... The photostimulated reaction of halonaphthalene with a series of carbanions derived from, propionic acid derivatives in liquid ammonia led to the naphthylation at a-carbon of the carbanions in an isolated yield ranging from 25% to 86%.In all cases,the dehalonaphthalenes were found to, be by-products and the reaction was inhibited by p-dinitrobenzere.An electron transfer from the carbanion to the halonaphthalene followed by ejection of halogen led to naphtbyl radical,as predicted by comparing the LUMOs of the carbanions and the halonaphthalenes,was involved in the process. Absence of the alkylnaphthalene and 1,2-dinaphthylalkane in the products indicates the smooth electron transfer between(Naph-Nu)^+ and Naph-X.C-vs.O-naphthylation is fully addressed in terms of MNDO calculations and acid-base principle. 展开更多
关键词 carbon atom of carbonyl and its equivalences Photochemical naphthylation at
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IMPROVED FABRICATION METHOD FOR CARBON NANOTUBE PROBE OF ATOMIC FORCE MICROSCOPY(AFM) 被引量:1
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作者 XU Zongwei DONG Shen +1 位作者 GUO Liqiu ZHAO Qingliang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2006年第3期373-375,共3页
An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy (AFM) here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two hig... An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy (AFM) here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two high precision microtranslators. When silicon probe and carbon nanotube are very close, several tens voltage is applied between them. And carbon nanotube is divided and attached to the end of silicon probe, which mainly due to the arc welding function. Comparing with the arc discharge method before, the new method here needs no coat silicon probe with metal film in advance, which can greatly reduce the fabrication's difficulty. The fabricated carbon nanotube probe shows good property of higher aspect ratio and can more accurately reflect the true topography of silicon grating than silicon probe. Under the same image drive force, carbon nanotube probe had less indentation depth on soft triblock copolymer sample than silicon probe. This showed that carbon nanotube probe has lower spring constant and less damage to the scan sample than silicon probe. 展开更多
关键词 carbon nanotube (CNT) atomic force microscope (AFM) Probe Fabrication
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Hybridization of Carbon Atomic Orbitals in the Carbon Cluster Cn
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作者 陈琼 王成瑞 《Chinese Science Bulletin》 SCIE EI CAS 1994年第21期1790-1794,共5页
In recent years,the stable existence of the C<sub>180</sub> has been observed in mass spectroscopy.The existence of C<sub>180</sub>, C<sub>540</sub>,…with I<sub>h</sub>... In recent years,the stable existence of the C<sub>180</sub> has been observed in mass spectroscopy.The existence of C<sub>180</sub>, C<sub>540</sub>,…with I<sub>h</sub> symmetry can be calculated theoretically, and it has been expected that C<sub>540</sub> is a stable construction. 展开更多
关键词 carbon cluster ELEMENTARY carbon POLYHEDRON atomIC ORBITAL hybridization.
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On-line Preconcentration of Trace Nickel from Electrolytic Manganese Using Minicolumn Packed Activated Carbon for Electrothermal Atomic Absorption Spectrometry 被引量:2
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作者 姚俊 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2004年第4期17-20,共4页
The online flow injection preconcentration and electrothermal atomic absorption spectrometry method were used for the determination of trace nickel in electrolytic manganese samples by sorption on a conical minicolumn... The online flow injection preconcentration and electrothermal atomic absorption spectrometry method were used for the determination of trace nickel in electrolytic manganese samples by sorption on a conical minicolumn packed with activated carbon at pH 9.0. The nickel was eluted from the minicolumn with 10%(v/v) nitric acid. An enrichment factor of 190-fold for a sample volume of 10mL was obtained. The detection limit (DL) of nickel with the use of the preconcentration method was 13ng·g -1in the original solid sample. The precision for 10 replicate determinations at 150ng·g -1 nickel concentration was 5.2% relative standard deviation (RSD). The calibration graph was linear with a correlation coefficient of r=0.9996 up to concentration of 660ng·g -1 nickel. 展开更多
关键词 online preconcentration NICKEL electrothermal atomic absorption spectrometry activated carbon electrolytic manganese
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THEORETICAL ANALYSIS AND EXPERIMENTAL STUDY OF CARBON NANOTUBE PROBE AND CONVENTIONAL ATOMIC FORCE MICROSCOPY PROBE ON SURFACE ROUGHNESS
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作者 WANG Jinghe WANG Hongxiang XU Zongwei DONG Shen WANG Shiqian ZHANG Huali 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第5期62-64,共3页
In this paper, three different tips are employed, i.e., the carbon nanotube tip, monocrystalline silicon tip and silicon nitride tip. Resorting to atomic force microscope (AFM), they are used for measuring the surfa... In this paper, three different tips are employed, i.e., the carbon nanotube tip, monocrystalline silicon tip and silicon nitride tip. Resorting to atomic force microscope (AFM), they are used for measuring the surface roughness of indium tin oxide (ITO) film and the immunoglobulin G (IgG) proteins within the scanning area of 10 μm×10 μm and 0.5 μm×0.5 μm, respectively. Subsequently, the scanned surface of the ITO film and IgG proteins are analyzed by using fractal dimension. The results show that the ffactal dimension measured by carbon nanotube tip is biggest with the highest frequency components and the most microscopic information. Therefore, the carbon nanotube tip is the ideal measuring tool for measuring super-smooth surface, which will play a more and more important role in the high-resolution imaging field. 展开更多
关键词 atomic force microscope carbon nanotube probes Fractal dimension
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Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry 被引量:3
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作者 XIAO Jun-ping ZHOU Qing-xiang BAI Hua-hua 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2007年第10期1266-1271,共6页
In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes (MWCNTs) and established a new method for the determination of trace cadmium in environment with flame atomic absorption ... In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes (MWCNTs) and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry. The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing. Parameters influencing the recoveries of target analytes were optimized. Under optimal conditions, the target analyte exhibited a good linearity (R^2=0.9992) over the concentration range 0.5-50 ng/ml. The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively. The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%. All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters. 展开更多
关键词 multiwalled carbon nanombes (MWCNTs) solid-phase extraction flame atomic absorption spectrometry
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Energetics and electronic structure of a single copper atomic chain wrapped in a carbon nanotube:a first-principles study
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作者 张建民 杜秀娟 +1 位作者 王素芳 徐可为 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第12期5468-5473,共6页
In the generalized gradient approximation, the energy and electronic structure are investigated for a single copper atomic chain wrapped in (4, 4), (5, 5) and (6, 6) armchair carbon nanotubes by using the first-... In the generalized gradient approximation, the energy and electronic structure are investigated for a single copper atomic chain wrapped in (4, 4), (5, 5) and (6, 6) armchair carbon nanotubes by using the first-principles projector-augmented wave potential within the framework of density functional theory. The results show that the (4, 4) and (5, 5) tubes are too narrow to wrap a Cu chain, but the (6, 6) tube is nearly ideal to wrap a Cu chain on its centre axis. Wider tubes are anticipated to wrap more than one Cu chain spontaneously with forces amounting to a fraction of a nanonewton. Although the tube-chain interaction decreases with the increase of the tube diameter of (4, 4), (5, 5) and (6, 6) successively, the charge density of the Cu@(6, 6) combined system still does not show complete superposition of that of the pristine (6, 6) tube and Cu chain. Successively reducing the restrictions of (4, 4), (5, 5) and (6, 6) tubes on the Cu chain leads to a reduction in shift of the highest peak of the Cu chain towards lower energies, that is from -0.5177 eV of the isolated Cu chain to -1.36785 eV, -0.668 eV and -0.588 eV for the Cu@(4, 4), Cu@(5, 5) and Cu@(6, 6) systems, respectively. In reverse, the strong metallic character of the Cu chain also enhances the metallic character of the combined systems so that the broader pseudogaps of the pristine carbon nanotubes around the Fermi level change into the narrow pseudogaps of the combined systems. 展开更多
关键词 copper atomic chain carbon nanotube electronic structures FIRST-PRINCIPLE
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Preconcentration of copper with multi-walled carbon nanotubes pretreated by potassium permanganate cartridge for solid phase extraction prior to flame atomic absorption spectrometry 被引量:2
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作者 Jun Ping Xiao Qing Xiang Zhou Hua Hua Bai 《Chinese Chemical Letters》 SCIE CAS CSCD 2007年第6期714-717,共4页
A procedure for the preconcentration of copper was described in this paper using multi-walled carbon nanotubes (MWCNTs) oxidized by potassium permanganate as the adsorbent for the enrichment of trace copper in water s... A procedure for the preconcentration of copper was described in this paper using multi-walled carbon nanotubes (MWCNTs) oxidized by potassium permanganate as the adsorbent for the enrichment of trace copper in water samples. Important parameters, such as the sample pH, the concentration and volume of eluent, sample flow rate and volume, and interference of coexisting ions, were investigated. The obtained results indicated that proposed method possessed an excellent analytical performance. The linear range, the detection limit, and precison (RSD) were 1–100 ng/mL (R(2) = 0.9993), 0.32 ng/mL and 2.88%, respectively. The results showed that copper could be adsorbed quantitatively on the pretreated MWCNTs with potassium permanganate, and proposed method was very useful in the monitoring of copper in the environment. 展开更多
关键词 Multi-walled carbon nanotubes Solid phase extraction (SPE) Flame atomic absorption spectrometry
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Determination of Carbon by Means of Microwave Plasma Torch Atomic Emission Spectrometry
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作者 ZHANG Han-qi YUAN Xiang-lin +1 位作者 YE Dong-mei ZHAO Xiao-jun and JIN Qin-han (Department Of Chemistry, Jilin University, Changchun, 130023)ZHU Zhi-ping(Department of Chemistry, Northeast Normal University, Changchun, 130024) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1996年第1期32-36,共5页
The determination of carbon by means of microwave plasma torch atomic emission spectrometry(MPT-AES) was studied. Aqueous samples were introduced with a pneumatic nebulization system. The detection limit for carbon wa... The determination of carbon by means of microwave plasma torch atomic emission spectrometry(MPT-AES) was studied. Aqueous samples were introduced with a pneumatic nebulization system. The detection limit for carbon was 0. 047μg/mL.The method was applied to the analysis for tap water and results were satisfactory. 展开更多
关键词 Microwave plasma torch atomic emission spectrometry carbon
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Problems on Hybridization of Carbon Atomic Orbitals in C_(60) Molecules
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作者 陈琼 王成瑞 《Chinese Science Bulletin》 SCIE EI CAS 1993年第11期916-919,共4页
Since the stable C<sub>60</sub> and C<sub>70</sub> carbon clusters with macroscopic quantity were prepared and separated successfully in laboratory, the studies of the new molecule have aroused... Since the stable C<sub>60</sub> and C<sub>70</sub> carbon clusters with macroscopic quantity were prepared and separated successfully in laboratory, the studies of the new molecule have aroused great attention. Investigation has been conducted on such elementary carbon polyhedrons from various angles and some achievements have been obtained. As far as the structure of the C<sub>60</sub> molecules is concerned, H. W. Kroto et al. proposed that it is of a thirty- 展开更多
关键词 ELEMENTARY carbon POLYHEDRON C60 molecule atomic orbital hybridization.
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Behavior of pure and modified carbon/carbon composites in atomic oxygen environment
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作者 Xiao-chong Liu Lai-fei Cheng +2 位作者 Li-tong Zhang Xin-gang Luan Hui Mei 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第2期190-195,共6页
Atomic oxygen (AO) is considered the most erosive particle to spacecraft materials in low earth orbit (LEO). Carbon fiber, car-bon/carbon (C/C), and some modified C/C composites were exposed to a simulated AO en... Atomic oxygen (AO) is considered the most erosive particle to spacecraft materials in low earth orbit (LEO). Carbon fiber, car-bon/carbon (C/C), and some modified C/C composites were exposed to a simulated AO environment to investigate their behaviors in LEO. Scanning electron microscopy (SEM), AO erosion rate calculation, and mechanical property testing were used to characterize the material properties. Results show that the carbon fiber and C/C specimens undergo significant degradation under the AO bombing. According to the effects of AO on C/C-SiC and CVD-SiC-coated C/C, a condensed CVD-SiC coat is a feasible approach to protect C/C composites from AO degradation. 展开更多
关键词 atomic oxygen OXIDATION carbon/carbon composites ceramic matrix composites
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Atomic Layer Deposition-Assisted Construction of Binder-Free Ni@N-Doped Carbon Nanospheres Films as Advanced Host for Sulfur Cathode 被引量:3
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作者 Jun Liu Aixiang Wei +4 位作者 Guoxiang Pan Qinqin Xiong Fang Chen Shenghui Shen Xinhui Xia 《Nano-Micro Letters》 SCIE EI CAS CSCD 2019年第4期147-160,共14页
Rational design of hybrid carbon host with high electrical conductivity and strong adsorption toward soluble lithium polysulfides is the main challenge for achieving high-performance lithium-sulfur batteries(LSBs).Her... Rational design of hybrid carbon host with high electrical conductivity and strong adsorption toward soluble lithium polysulfides is the main challenge for achieving high-performance lithium-sulfur batteries(LSBs).Herein,novel binder-free Ni@N-doped carbon nanospheres(N-CNSs)films as sulfur host are firstly synthesized via a facile combined hydrothermal-atomic layer deposition method.The cross-linked multilayer N-CNSs films can effectively enhance the electrical conductivity of electrode and provide physical blocking“dams”toward the soluble long-chain polysulfides.Moreover,the doped N heteroatoms and superficial NiO layer on Ni layer can work synergistically to suppress the shuttle of lithium polysulfides by effective chemical interaction/adsorption.In virtue of the unique composite architecture and reinforced dual physical and chemical adsorption to the soluble polysulfides,the obtained Ni@N-CNSs/S electrode is demonstrated with enhanced rate performance(816 mAh g?1 at 2 C)and excellent long cycling life(87%after 200 cycles at 0.1 C),much better than N-CNSs/S electrode and other carbon/S counterparts.Our proposed design strategy offers a promising prospect for construction of advanced sulfur cathodes for applications in LSBs and other energy storage systems. 展开更多
关键词 atomic layer deposition Nickel N-DOPED carbon NANOSPHERES SULFUR CATHODE Lithium-sulfur batteries
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Spin-Dependent Transport in Carbon Nanotubes with Chromium Atoms
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作者 Stanislav P. Repetsky Oleg V. Tretyak +1 位作者 Iryna G. Vyshivanaya Dmitriy K. Cheshkovskiy 《Journal of Modern Physics》 2014年第17期1896-1891,共7页
Method is developed for self-consistent calculation of the energy spectrum of free energy and electrical disordered crystals. Processes of electron scattering on the ionic core potential of different sort, fluctuation... Method is developed for self-consistent calculation of the energy spectrum of free energy and electrical disordered crystals. Processes of electron scattering on the ionic core potential of different sort, fluctuations of charge, spin density and lattice vibrations are taken into account. Electronic states of the system are described using tight binding multiband model. The nature of the spin-dependent electron transport of carbon nanotubes with chromium atoms adsorbed on the surface is explained. The value of the spin polarization of electron transport is determined by the difference of the partial densities of states of electrons with opposite spin projection at the Fermi level and the difference between the relaxation times of electron states. The value of the spin polarization of the electric current increases with increasing of Cr atoms concentration and magnitude of the external magnetic field. 展开更多
关键词 Spin-Dependent Transport carbon NANOTUBES with CHROMIUM atomS TIGHT Binding Model Localized Magnetic MOMENT Free Energy Electrical Conductivity TENSOR
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Determination of Atomic Fractions of Isotopes Carbon-13 and Nitrogen-15 Directly in Glicine, L-Leucine, Isoleucine and Alanine
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作者 Levani Eliashvili Lamzira Parulava Vakhtang Betlemidze 《American Journal of Analytical Chemistry》 CAS 2023年第5期229-237,共9页
Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the cas... Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible. 展开更多
关键词 Mass Spectrometer Mass Spectrum Fragmentary Ion Ionization Mass-to-Charge Ratio Intensity of Ionic Current carbon-13 Nitrogen-15 atomic Fraction Isotope-Modified
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Positively charged carbon electrocatalyst for enhanced power performance of L-ascorbic acid fuel cells 被引量:1
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作者 Myounghoon Choun Hye Jin Lee Jaeyoung Lee 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第5期793-797,共5页
Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functio... Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functional groups and its electro-catalytic activity is still unclear. In this paper, we prepared different levels of oxidized carbons by a simple acid treatment and investigated the correlation between the surface oxygen functional groups of acid-treated carbon and electro-catalytic activity in an electrooxidation of L-ascorbic acid. Positively charged carbon was demonstrated by lone pair electron of oxygen from valence band spectra study. It was revealed that the positively charged carbon, especially involved in carbonyl, showed enhanced the electro-catalytic activity through both better adsorption of negatively charged reactants and lowered LUMO by electronegativity of oxygen. 展开更多
关键词 Vitamin-C electrooxidation ELECTRONEGATIVITY carbon atomic charge Surface oxygen
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A Scheme for Calculating Atomic Structures beyond the Spherical Approximation 被引量:1
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作者 Mitiyasu Miyasita Katsuhiko Higuchi Masahiko Higuchi 《Journal of Modern Physics》 2011年第5期421-430,共10页
We present a scheme for calculating atomic single-particle wave functions and spectra with taking into ac-count the nonspherical effect explicitly. The actual calculation is also performed for the neutral carbon atom ... We present a scheme for calculating atomic single-particle wave functions and spectra with taking into ac-count the nonspherical effect explicitly. The actual calculation is also performed for the neutral carbon atom within the Hartree-Fock-Slater approximation. As compared with the conventional atomic structure of the spherical approximation, the degenerate energy levels are split partially. The ground state values of the total orbital and spin angular momenta are estimated to be both about unity, which corresponds to the term P3PP in the LS-multiplet theory. This means that the nonspherical effect may play an essential role on the description of the magnetization caused by the orbital polarization. 展开更多
关键词 Nonspherical Distribution Of ELECTRONS SPHERICAL APPROXIMATION ORBITAL Polarization atomic Structure carbon atom
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The decisive role of adsorbed OH^(*)in low‐potential CO electro‐oxidation on single‐atom catalytic sites 被引量:1
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作者 Yang Li Xian Wang +7 位作者 Ying Wang Zhaoping Shi Yuqi Yang Tuo Zhao Zheng Jiang Changpeng Liu Wei Xing Junjie Ge 《Carbon Energy》 SCIE EI CAS CSCD 2023年第9期63-73,共11页
CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catal... CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis. 展开更多
关键词 adsorbed CO^(*)and OH^(*) carbon‐based Rh single‐atom catalysts CO electro‐oxidation reaction electron interaction MNx moiety
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