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Effects of surface oxide species and contents on SiC slurry viscosity 被引量:3
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作者 NING Shufan LI Hongyan +2 位作者 CHEN Wei LIU Bin CHEN Shoutian 《Rare Metals》 SCIE EI CAS CSCD 2005年第3期240-245,共6页
The disadvantageous effects of colloidal SiO2 layer and micro-content of metal oxide adsorbed on SiC powder surface on SiC slurry stable dispersion were studied, and the novel method to avoid this disadvantage was pro... The disadvantageous effects of colloidal SiO2 layer and micro-content of metal oxide adsorbed on SiC powder surface on SiC slurry stable dispersion were studied, and the novel method to avoid this disadvantage was proposed. By acidwashing, on the one hand, because the maximum Zeta potential of SiC powder increases to 72.49 mV with the decreasing content of metal oxide adsorbed on the SiC powder surface, the repulsion force between SiC powders that dispersed in slurry is enhanced, thus the SiC powder can be fully dispersed in slurry. On the other hand, after HF acidwashing, with the OH^- group adsorbed on SiC powder surface destroyed and replaced by the Fion, the hydrogen bond adsorbed on the OHgroup is also destroyed. Therefore, the surface property of the SiC powder is changed from hydrophilic to hydrophobic; H2O that adsorbed on SiC powder surface is released and can flow freely, and it actually increases the content of the effective flow phase in the slurry. These changes of SiC powder surface property can be proved by XPS and FTIR analysis. Finally, the viscosity of SiC slurry is decreased greatly, and when the viscosity of the slurry is lower than 1 Pa·s, the solid volume fraction of SiC powder in the slurry is maximized to 61.5 vol.%. 展开更多
关键词 SiC powder water base slurry acidwashing surface oxide Zeta potential HYDROPHOBIC slurry viscosity
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XPS STUDIES OF OXIDATION BEHAVIOR OF NICKEL AND THERMAL STABILITY OF SURFACE OXIDES 被引量:1
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作者 ZHAO Liangzhong PAN Chenghuang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1989年第8期133-137,共5页
Surface oxidation of polycrystalline nickel foil in air and pure water at different temperatures and the thermal stability of the surface oxides have been investigated by means of XPS.In ad- dition to NiO,Ni_2O_3 is f... Surface oxidation of polycrystalline nickel foil in air and pure water at different temperatures and the thermal stability of the surface oxides have been investigated by means of XPS.In ad- dition to NiO,Ni_2O_3 is formed especially after long periods of air exposure.Nickel surfaces are much less reactive to pure water than to air.The thermal stability of the surface oxides is related to oxidative temperature.The surface species of oxides formed by air exposure at temperatures below 120℃ can be reduced into nickel metal after heating the sample in vacuum at 300℃ for only 10 minutes (in the case of room temperature) to 1 h (in the case of 120℃). This reduction is caused by reaction with surface carbon contaminants.However,the surface species of nickel oxides formed by air exposure with heating at temperatures above 200℃ can not be reduced into metal after heating the sample in vacuum at 300℃ for 1h. 展开更多
关键词 XPS NICKEL surface oxide thermal stability
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Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation
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作者 Qiancheng Zhang Limin Zhang +3 位作者 Feng Jiang Honghu Tang Li Wang Wei Sun 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第2期261-267,共7页
The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challe... The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena. 展开更多
关键词 GALENA CHALCOPYRITE ferric ions flotation separation surface oxidation
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A review of ^(17)O isotopic labeling techniques for solid-state NMR structural studies of metal oxides in lithium-ion batteries
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作者 Xiaoli Xia Lei Zhu +2 位作者 Weiping Tang Luming Peng Junchao Chen 《Magnetic Resonance Letters》 2024年第2期46-53,共8页
Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structur... Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structural and dynamic details.Herein,we commence with a brief introduction to recent research on lithium-ion battery oxide materials studied using ^(17)O solid-state NMR spectroscopy.Then we delve into a review of ^(17)O isotopic labeling methods for tagging oxygen sites in both the bulk and surfaces of metal oxides.At last,the unresolved problems and the future research directions for advancing the ^(17)O labeling technique are discussed. 展开更多
关键词 ^(17)O solid-state NMR ^(17)O isotopic labeling methods Bulk and surfaces of metal oxides DFT calculation
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Formation mechanism of surface oxide layer of grain-oriented silicon steel 被引量:3
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作者 Jia-long Qiao Fei-hu Guo +2 位作者 Sheng-tao Qiu Xing-zhong Zhang Hai-jun Wang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2021年第3期327-334,共8页
The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the ... The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the calculation of thermodynamics and kinetics.The surface oxide layer with 2.3μm in thickness is mainly composed of SiO_(2),a small amount of FeO and Fe_(2)SiO_(4).During the formation of surface oxide layer,the restriction factor was the diffusion of O in the oxide layer.At the initial stage of the decarburization annealing,FeO would be formed on the surface layer.SiO_(2) and silicate particles rapidly nucleated,grew and formed a granular oxide layer in the subsurface.As the oxidation layer thickens,the nucleation of new particles decreases,and the growth of oxide particles would be dominant.A lamellar oxide layer was formed between the surface oxide layer and the steel matrix,and eventually formed a typical three-layer structure.During the high temperature annealing,MgO mainly reacted with SiO_(2) and Fe_(2)SiO_(4) in the surface oxide layer to form Mg2SiO_(4) and Fe_(2)SiO_(4) would respond first,thus forming the glass film with average thickness of 4.87μm. 展开更多
关键词 Grain-oriented silicon steel Decarburizing annealing surface oxide layer Formation mechanism Glass film
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Importance of surface oxide for the tribology of a Zr-based metallic glass 被引量:4
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作者 S.J.KANG K.T.RITTGEN +3 位作者 S.G.KWAN H.W.PARK R.BENNEWITZ A.CARON 《Friction》 CSCD 2017年第1期115-122,共8页
Thermally grown surface oxide layers dominate the single-asperity tribological behavior of a Zr60Cu30Al10 glass.Increase in oxidation time leads to an increased contribution of shearing and a corresponding decreased c... Thermally grown surface oxide layers dominate the single-asperity tribological behavior of a Zr60Cu30Al10 glass.Increase in oxidation time leads to an increased contribution of shearing and a corresponding decreased contribution of ploughing to friction.This change in the dominating friction and wear mechanism results in an overall minor decrease of the friction coefficient of oxidized surfaces compared to the metallic glass sample with native surface oxide.Our results demonstrate the importance of creating a stable oxide layer for practical applications of metallic glasses in micro-devices involving sliding contact. 展开更多
关键词 metallic glasses surface oxide FRICTION WEAR NANOTRIBOLOGY atomic force microscopy
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Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron sputtering 被引量:2
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作者 王学进 梁春军 +6 位作者 管康萍 李德华 聂玉昕 朱世秋 黄峰 张葳葳 成正维 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第9期3512-3515,共4页
This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering, and then aged under circumstance for years. Samples were chara... This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering, and then aged under circumstance for years. Samples were characterized with several different techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, and Raman, when they were fresh from sputter chamber and aged after years, respectively, in order to determine their structure and composition. It finds that a small amount of sodium occurred on the surface of vanadium dioxide films, which was probably due to sodium ion diffusion from soda-lime glass when sputtering was performed at high substrate temperature. It also finds that aging for years significantly affected the nonstoichiometry of vanadium dioxide films, thus inducing much change in Raman modes. 展开更多
关键词 surface oxidation vanadium dioxide FILMS magnetron sputtering
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INVESTIGATION OF BEHAVIOR OF AMMONIUM SULFATE ON SURFACE OF IRON OXIDE Rong Sheng LI~*, Jing Feng CHEN, Hun YANG, Wu Yang ZHANG Dept. of Chemistry, Jilin University, Changchun 130023,
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作者 Quan WEI Testing Center, Jilin University 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第5期463-466,共4页
hhen ammonium sulfate-iron oxide is treated below 573 K, ammonium sulfate can spontaneously desperse on the surface of iron oxide. Simultaneously ammonium sulfate decomposes to some extent. During or after the dispers... hhen ammonium sulfate-iron oxide is treated below 573 K, ammonium sulfate can spontaneously desperse on the surface of iron oxide. Simultaneously ammonium sulfate decomposes to some extent. During or after the dispersion, sulfate ion can interact with Fe atom on the surface of iron oxide to form a sort of surface sulfato complex of Fe and thus is transformed from the isolated into the bidentately bound form. Above 573 K the sulfato complex of Fe will gradually decompose with a further increase in temperature. 展开更多
关键词 of Chemistry Wu Yang ZHANG Dept Jing Feng CHEN INVESTIGATION OF BEHAVIOR OF AMMONIUM SULFATE ON surface OF IRON oxide Rong Sheng LI Jilin University Changchun 130023 Hun YANG
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New Evidences for the Adsorption of Methane over Oxide Surfaces
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作者 Fa Qiang XU Shi Kong SHEN Jin Zhen XUE(National Synchrotron Radiation Laboratory.University of Science and Technology of China.Hefei 230029.)(Key State Laboratory for Oxo Synthesis and Selective Oxidation. Lanzhou Institute of Chemical Physics.Chinese Ac 《Chinese Chemical Letters》 SCIE CAS CSCD 1996年第9期875+873-874,共3页
It is indicative of the TSR result that CH4 was strongly adsorbed on well degassed SrCO3 surface at high temperatUre.A desorption peak of CH4 was found in CH4TPD profile which appeared at ca. 310℃.The strong adsorpti... It is indicative of the TSR result that CH4 was strongly adsorbed on well degassed SrCO3 surface at high temperatUre.A desorption peak of CH4 was found in CH4TPD profile which appeared at ca. 310℃.The strong adsorption of CH4 over the surface of SrCO3 was attributed to the strong basicity of SrO sites resulted from decomposition of SrCO_3 展开更多
关键词 OVER New Evidences for the Adsorption of Methane over oxide surfaces
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Study on the surface of hydrous titanium oxide adsorbent for extracting uranium from seawater-Ⅱ. The surface of HTO
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作者 Chen Huizhen and Jiang Anbei Third Institute of Oceanography, State Oceanic Administration, Xiamen, ChinaLanzhou Institute of Chemical Physics, Academia Sinica, Lanzhou, China Present address: Analysis and Testing Centre, Xiamen University, Xiamen, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1991年第1期83-92,共10页
This is second paper summarizing the study on the hydrous titanium oxide absorbent for extracting uranium fromseawater. The investigation is performed by means of X- ray photoelectronic energy spectroscopy for chemica... This is second paper summarizing the study on the hydrous titanium oxide absorbent for extracting uranium fromseawater. The investigation is performed by means of X- ray photoelectronic energy spectroscopy for chemical analysis ( ESC A ) , determination of surface hydroxy radical, Fourier-transfer infrared spectrophotometry (FT-IR ) , electron paramagnetic resonance (EPR), inductively coupled Plasma torch (ICP), etc. The emphasis is laid upon the exploration of HTO surface and a discussion about the adsorption micromechanism. 展开更多
关键词 In Study on the surface of hydrous titanium oxide adsorbent for extracting uranium from seawater The surface of HTO
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First-principle calculations of interaction of O_2 with pyrite, marcasite and pyrrhotite surfaces 被引量:2
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作者 赵翠华 陈建华 +2 位作者 李玉琼 陈晔 李伟洲 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第2期519-526,共8页
The interaction of O2 with pyrite, marcasite and pyrrhotite surfaces was studied using first-principle calculations to obtain the oxidization mechanisms of these minerals. The results show that the adsorption energy o... The interaction of O2 with pyrite, marcasite and pyrrhotite surfaces was studied using first-principle calculations to obtain the oxidization mechanisms of these minerals. The results show that the adsorption energy of O2 on pyrrhotite surface is the largest, followed by that on marcasite surface and then pyrite surface. O2 molecules adsorbed on pyrite, marcasite and pyrrhotite surfaces are all dissociated. The oxygen atoms and surface atoms of pyrite, marcasite and pyrrhotite surfaces have different bonding structures. Due to more atoms on pyrrhotite and marcasite surfaces interaction with oxygen atoms, the adsorption energies of O2 on pyrrhotite and marcasite surfaces are larger than that on pyrite surface. Larger values of Mulliken populations for O?Fe bond of pyrrhotite surface result in relative larger adsorption energy compared with that on marcasite surface. 展开更多
关键词 iron sulfide O2 adsorption surface oxidation FIRST-PRINCIPLE
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Impact of oxygen incorporation on interface optimization and defect suppression for efficiency enhancement in Cu_(2)ZnSn(S,Se)_(4)solar cells
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作者 Shicheng Deng Songfan Wang +7 位作者 Yuanyuan Wang Qian Xiao Yuena Meng Dongxing Kou Wenhui Zhou Zhengji Zhou Zhi Zheng Sixin Wu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第8期77-85,I0003,共10页
Kesterite Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells suffer from severe carrier recombination,limiting the photovoltaic performance.Unfavorable energy band alignment at the p-n junction and defective front interface are ... Kesterite Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)solar cells suffer from severe carrier recombination,limiting the photovoltaic performance.Unfavorable energy band alignment at the p-n junction and defective front interface are two main causes.Herein,oxygen incorporation in CZTSSe via absorber air-annealing was developed as a strategy to optimize its surface photoelectric property and reduce the defects.With optimized oxygen incorporation conditions,the carrier separation and collection behavior at the front interface of the device is improved.In particular,it is found that oxygen incorporated absorber exhibits increased band bending,larger depletion region width,and suppressed absorber defects.These indicate the dynamic factors for carrier separation become stronger.Meanwhile,the increased potential difference between grain boundaries and intra grains combined with the decreased concentration of interface deep level defect in the absorber provide a better path for carrier transport.As a consequence,the champion efficiency of CZTSSe solar cells has been improved from 9.74%to 12.04%with significantly improved open-circuit voltage after optimized air-annealing condition.This work provides a new insight for interface engineering to improve the photoelectric conversion efficiency of CZTSSe devices. 展开更多
关键词 KESTERITE Thin film solar cell Interface optimization surface oxidation Defect suppression
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Water-oxygen interaction on marcasite(101)surface:DFT calculation 被引量:4
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作者 Junjie Zhang Yuqiong Li Jianhua Chen 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第1期191-199,共9页
Marcasite(FeS2)is widespread in nature,its oxidation plays a vital role in acid mine drainage,mineral resource recovery,and photoelectric material applications.In this paper,the oxidation mechanism of marcasite has be... Marcasite(FeS2)is widespread in nature,its oxidation plays a vital role in acid mine drainage,mineral resource recovery,and photoelectric material applications.In this paper,the oxidation mechanism of marcasite has been studied for the first time using density functional theory(DFT).It is found that,unlike the oxidation of pyrite,the oxidation of marcasite merely occurs at surface S atoms.Under the coexistence of water and oxygen,S atoms around surface Fe atoms are replaced by O atoms.The surface S sites are initially oxidized to form S==O bonds,and continue to adsorb oxygen to gradually generate SO3^2-,SO4^2-species,and eventually FeSO4.In this process,H2O molecules participate in neither oxidation nor dissociation,and they are adsorbed on surface Fe sites in the form of molecules,i.e.,all O atoms in SO4^2-derive from oxygen rather than water molecules. 展开更多
关键词 MARCASITE surface oxidation ADSORPTION Density functional theory
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Effect of deep oxidation of chalcopyrite on surface properties and flotation performance 被引量:2
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作者 Qingyun Luo Qing Shi +2 位作者 Dezhi Liu Binbin Li Saizhen Jin 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第4期907-914,共8页
In this study, chalcopyrite was oxidized in hydrogen peroxide(H_(2)O_(2)) solutions of different concentrations to simulate different degrees of oxidation in real ores, and the effects of H_(2)O_(2) treatment on chalc... In this study, chalcopyrite was oxidized in hydrogen peroxide(H_(2)O_(2)) solutions of different concentrations to simulate different degrees of oxidation in real ores, and the effects of H_(2)O_(2) treatment on chalcopyrite surface properties and flotation performance were investigated by surface analysis techniques and floatation experiments, which implied the reason for the poor grade and recovery of oxidized chalcopyrite concentrate in the production process of the ore. Flotation results showed that when the concentration of H_(2)O_(2) increased from 0%(by weight) to 5%, the flotation recovery of chalcopyrite decreased sharply.However, with increasing H_(2)O_(2) concentration from 5% to 30%, chalcopyrite recovery improved relatively to different degrees with different collector concentrations. Analyses of X-ray photoelectron spectroscopy(XPS) and inductively coupled plasma-atomic optical emission spectrophotometry(ICP-OES) results indicated that the pretreatment with H_(2)O_(2) caused that hydrophilic substance formed on chalcopyrite surface with the dissolution of copper ions, and the dissolution amount of copper increased with the increase of H_(2)O_(2) concentration. UV–visible spectrophotometer and Fourier transform infrared spectrum(FTIR) studies indicated that the pretreatment of chalcopyrite with H_(2)O_(2) had little effect on the adsorption amount of potassium butyl xanthate(PBX) on chalcopyrite surface. However, due to the dissolution of copper ions, PBX interacted with chalcopyrite mainly as buthyl dixanthogen(BX)_(2). 展开更多
关键词 CHALCOPYRITE surface oxidation FLOTATION surface analysis
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Enhanced oxygen reduction reaction performance over Pd catalysts by oxygen-surface-modified SiC 被引量:1
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作者 Jing Li Xiang Sun +3 位作者 Yongzheng Duan Dongmei Jia Yuejin Li Jianguo Wang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第6期963-970,共8页
Obtaining a detailed understanding of the surface modification of supports is crucial;however,it is a challenging task for the development and large-scale fabrication of supported electrocatalysts that can be used as ... Obtaining a detailed understanding of the surface modification of supports is crucial;however,it is a challenging task for the development and large-scale fabrication of supported electrocatalysts that can be used as alternatives to Pt-based catalysts for the oxygen reduction reaction(ORR).In this study,commercial silicon carbide(SiC)was modified through surface oxidization(O-SiC)to support the use of Pd nanoparticles(Pd NPs)as electrocatalysts for ORR.The obtained Pd/O-SiC catalysts exhibited better ORR activity,stronger durability,and higher resistance to methanol poisoning than that exhibited by commercial Pt/C.The role of the support in enhancing the ORR performance,especially the oxidization of SiC surfaces,was discussed in detail based on the experimental characterizations and density functional theory calculations.The underlying mechanism of the superior ORR performance of Pd/O-SiC catalysts was attributed to the charge transfer from SiC_(x)O_(y)to Pd NPs on the surfaces of SiC and the strong metal–support interactions(SMSIs)between Pd and SiC_(x)O_(y).The charge transfer enhanced the ORR activity by inducing electron-rich Pd,increased the adsorption of the key intermediate OOH,and decreased the Gibbs free energy of the critical ORR step.Furthermore,SMSIs enhanced the ORR stability of the Pd/O-SiC catalyst.This study provided a facile route for designing and developing highly active Pd-based ORR electrocatalysts. 展开更多
关键词 Silicon carbide surface oxidization Oxygen reduction reaction Density functional theory Charge transfer Electron-rich Pd
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Compounded Surface Modification of ZK60 Mg Alloy by High Current Pulsed Electron Beam+Micro-plasma Oxidation 被引量:3
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作者 高波 郝仪 +3 位作者 涂赣峰 石为喜 于福晓 李世伟 《Plasma Science and Technology》 SCIE EI CAS CSCD 2010年第1期67-70,共4页
In this study, compounded surface modification technology-high current pulsed electron beam (HCPEB) + micro-plasma oxidation (MPO) was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of... In this study, compounded surface modification technology-high current pulsed electron beam (HCPEB) + micro-plasma oxidation (MPO) was applied to treat ZK60 Mg alloys. The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB+MPO compounded treatment were investigated by SEM. The results showed that the density of the ceramic layer of HCPEB+MPO-treated ZK60 Mg alloy was improved and defects were reduced compared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treated by HCPEB+MPO was divided into three zones, namely the top loose ceramic zone, middle compact zone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy before and after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamic polarization curves. It was found that the corrosion current density of ZK60 Mg alloys could be reduced by about three orders of magnitude, from 311μA/cm^2 of the original sample to 0.2μA/cm^2 of the HCPEB+MPO-treated sample. This indicates the great application potential of the HCPEB+MPO compounded surface modification technology in improving the corrosion resistance of ZK60 Mg alloys in the future. 展开更多
关键词 ZK60 Mg alloy high current pulsed electron beam micro-plasma oxidation compounded surface modification corrosion resistance
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Unraveling the catalytically active phase of carbon dioxide hydrogenation to methanol on Zn/Cu alloy: Single atom versus small cluster 被引量:1
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作者 Xiao-Kuan Wu Hui-Min Yan +3 位作者 Wei Zhang Jie Zhang Guang-Jie Xia Yang-Gang Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第10期582-593,I0015,共13页
Methanol synthesis from CO_(2)hydrogenation catalyzed by Zn/Cu alloy has been widely studied,but there is still debate on its catalytic active phase and whether the Zn can be oxidized during the reaction process.What ... Methanol synthesis from CO_(2)hydrogenation catalyzed by Zn/Cu alloy has been widely studied,but there is still debate on its catalytic active phase and whether the Zn can be oxidized during the reaction process.What is more,as Zn atoms could locate on Zn/Cu alloy surface in forms of both single atom and cluster,how Zn surface distribution affects catalytic activity is still not clear.In this work,we performed a systematic theoretical study to compare the mechanistic natures and catalytic pathways between Zn single atom and small cluster on catalyst surface,where the surface oxidation was shown to play the critical role.Before surface oxidation,the Zn single atom/Cu is more active than the Zn small cluster/Cu,but its surface oxidation is difficult to take place.Instead,after the easy surface oxidation by CO_(2)decomposition,the oxidized Zn small cluster/Cu becomes much more active,which even exceeds the hardlyoxidized Zn single atom/Cu to become the active phase.Further analyses show this dramatic promotion of surface oxidation can be ascribed to the following factors:i)The O from surface oxidation could preferably occupy the strongest binding sites on the center of Zn cluster.That makes the O intermediates bind at the Zn/Cu interface,preventing their too tight binding for further hydrogenation;ii)The higher positive charge and work function on the oxidized surface could also promote the hydrogenation of O intermediates.This work provided one more example that under certain condition,the metal cluster can be more active than the single atom in heterogeneous catalysis. 展开更多
关键词 CO_(2)hydrogenation surface oxidation Zn/Cu alloy Catalytically active phase
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Surface magnetization of siderite mineral 被引量:5
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作者 Wu Xiqing Xu Pengyun +2 位作者 Duan Yunfeng Hu Cong Li Guoping 《International Journal of Mining Science and Technology》 SCIE EI 2012年第6期816-821,共6页
Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-cont... Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature,pH value,stirring rate and reaction time.No addition of any iron-containing reagent is required.The temperature of 60 ℃,NaOH concentration of 0.10 mol/L;stirring rate of 900 r/min and the reaction time of 10 min are the optimal conditions.The results show that the siderite recovery in magnetic separation increased from 26.9% to 88.8% after surface magnetization.Magnetization kinetic equation is expressed as 1 [1(e0.269)]1/3 = Kt.Activation energy for the magnetization reaction is 4.30 kJ/mol.VSM,SEM and XPS were used to characterize the siderite,and results show that the saturated magnetization(rs) of siderite increased from 0.652 to 2.569Am2 /kg,the magnetic hysteresis was detected with a coercive force of 0.976 A/m after magnetization;Fe2P3/2 electron binding energy changed which reflects the valence alteration in iron on the surface and the formation of ferromagnetic Fe3O4. 展开更多
关键词 Iron ores Magnetic separation surface magnetization Air oxidation Fe3O4 chemical synthesis
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Surface modifications of biometallic commercially pure Ti and Ti–13Nb–13Zr alloy by picosecond Nd:YAG laser 被引量:1
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作者 Slađana Laketić Marko Rakin +3 位作者 MilošMomčilović Jovan Ciganović Đorđe Veljović Ivana Cvijović-Alagić 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2021年第2期285-295,共11页
The effects of picosecond Nd:YAG laser irradiation on chemical and morphological surface characteristics of the commercially pure titanium and Ti–13Nb–13Zr alloy in air and argon atmospheres were studied under diffe... The effects of picosecond Nd:YAG laser irradiation on chemical and morphological surface characteristics of the commercially pure titanium and Ti–13Nb–13Zr alloy in air and argon atmospheres were studied under different laser output energy values.During the interaction of laser irradiation with the investigated materials,a part of the energy was absorbed on the target surface,influencing surface modifications.Laser beam interaction with the target surface resulted in various morphological alterations,resulting in crater formation and the presence of microcracks and hydrodynamic structures.Moreover,different chemical changes were induced on the target materials’surfaces,resulting in the titanium oxide formation in the irradiation-affected area and consequently increasing the irradiation energy absorption.Given the high energy absorption at the site of interaction,the dimensions of the surface damaged area increased.Consequently,surface roughness increased.The appearance of surface oxides also led to the increased material hardness in the surface-modified area.Observed chemical and morphological changes were pronounced after laser irradiation of the Ti–13Nb–13Zr alloy surface. 展开更多
关键词 commercially pure titanium Ti-13Nb-13Zr alloy surface modification Nd:YAG laser laser-induced damage hard oxidized surface
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Highly stable two-dimensional graphene oxide:Electronic properties of its periodic structure and optical properties of its nanostructures 被引量:1
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作者 张琴 张红 程新路 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第2期533-539,共7页
According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide(C_2O).Using density functional theory(DFT), C_2O is found to be a direct gap semiconductor. In additi... According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide(C_2O).Using density functional theory(DFT), C_2O is found to be a direct gap semiconductor. In addition, we obtain the absorption spectra of the periodic structure of C_2O, which show optical anisotropy. To study the optical properties of C_2O nanostructures, time-dependent density functional theory(TDDFT) is used. The C_2O nanostructure has a strong absorption near 7 eV when the incident light polarizes along the armchair-edge. Besides, we find that the optical properties can be controlled by the edge configuration and the size of the C_2O nanostructure. With the elongation strain increasing, the range of light absorption becomes wider and there is a red shift of absorption spectrum. 展开更多
关键词 two-dimensional(2D) materials graphene oxide surface plasmons
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