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Defect engineering of water-dispersible g-C_(3)N_(4) photocatalysts by chemical oxidative etching of bulk g-C_(3)N_(4) prepared in different calcination atmospheres 被引量:3
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作者 Thi Kim Anh Nguyen Thanh-Truc Pham +2 位作者 Bolormaa Gendensuren Eun-Suok Oh Eun Woo Shin 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2022年第8期232-243,共12页
In this study,water-dispersible graphitic carbon nitride(g-C_(3)N_(4))photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C_(3)N_(4) that was polymerized thermally in different... In this study,water-dispersible graphitic carbon nitride(g-C_(3)N_(4))photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C_(3)N_(4) that was polymerized thermally in different calcination atmospheres such as air,CO_(2),and N_(2).The different calcination atmospheres directly influenced the physicochemical and optical properties of both bulk and water-dispersible g-C_(3)N_(4),changing the photocatalytic degradation behavior of methylene blue(MB)and tetracycline hydrochloride(TCHCl)for water-dispersible g-C_(3)N_(4).The bubble-burst process in the thermal polymerization of thiourea produced defective edges containing C=O groups that preferred substituting the C-NHx groups over bulk g-C_(3)N_(4).In the oxygen-free N_(2) atmosphere among the different calcination atmospheres,more C=O functional groups were generated on the defective edges of bulk g-C_(3)N_(4),resulting in the highest N vacancy of the tri-s-triazine structure.During the successive chemical oxidation,S-or O-containing functional groups were introduced onto water-dispersible g-C_(3)N_(4).The water-dispersible g-C_(3)N_(4) photocatalyst from the oxygen-free N_(2) atmosphere(NTw)contained the most O-and S-functional groups on the g-C_(3)N_(4) surface.Consequently,NTw exhibited the highest photocatalytic activity in the MB and TC-HCl photodegradation because of its slowest recombination process,which was ascribed to the unique surface properties of NTw such as abundant functional groups on the defective edges and N-deficient property. 展开更多
关键词 g-C_(3)N_(4) Water-dispersible photocatalyst Calcination atmosphere Charge separation Chemically oxidative etching Defect edges
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Controlled oxidative etching of gold nanorods revealed through in-situ liquid cell electron microscopy
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作者 Wen Wang Tao Xu +7 位作者 Tingting Bai Chao Zhu Qiubo Zhang Hongtao Zhang Hui Zhang Zhirui Guo Haimei Zheng Litao Sun 《Science China Materials》 SCIE EI CSCD 2020年第12期2599-2605,共7页
Oxidative etching can be a powerful approach to modify the morphology of nanoscale materials for various applications.Unveiling of the etching mechanisms and morphological evolution during etching is critical.Using th... Oxidative etching can be a powerful approach to modify the morphology of nanoscale materials for various applications.Unveiling of the etching mechanisms and morphological evolution during etching is critical.Using the liquid cell transmission electron microscopy,we investigate the etching behavior of gold nanorods under different electron beam dose rates:caseⅠ,3.5×10^9 Gy s^-1;caseⅡ,1.5×10^10 Gy s^-1;caseⅢ,4.5×10^10 Gy s^-1.The Au nanorod develops facets at the tips(caseⅠ)or adopts a transit ellipsoid shape and eventually dissolves(caseⅡ),depending on the dose rate.The rapid etching under an even higher dose rate(caseⅢ)may lead to the formation of Au3+ion-rich intermediates around the nanorod,which further accelerates the lateral etching and unexpectedly increases the aspect ratio of the nanorod.Our quantitative analysis shows that the critical size of the nanorod,below which the etching rate increases significantly with the reduction of nanorod size,may vary subject to the degree that the system is away from equilibrium.These results provide significant insights into the oxidative etching mechanisms and shed light on the rational design and synthesis of nanostructures. 展开更多
关键词 in-situ liquid transmission electron microscope oxidative etching etching mechanism electron dose rate GOLD
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Influence of surface etching pretreatment on PEO process of eutectic Al–Si alloy 被引量:1
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作者 李康 李文芳 +2 位作者 张果戈 王敏 唐鹏 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第9期1572-1578,共7页
To solve the problems generally encountered during the plasma electrolytic oxidation(PEO) of Al alloys with high Si content, a pretreatment of chemical etching was applied before the process. The influence of such pre... To solve the problems generally encountered during the plasma electrolytic oxidation(PEO) of Al alloys with high Si content, a pretreatment of chemical etching was applied before the process. The influence of such pretreatment was studied by SEM, EDS and XRD. The pretreatment presents a significant effect on positive voltage at the beginning stage of PEO, leading to higher voltage over the whole process. The difference between the positive voltages of non-etched and etched specimens decreases gradually with the increase of processing time. The pretreatment exhibits much less influence on the negative voltage. For the sample with surface pretreatment, the average growth rate of PEO coating is increased from 0.50 to 0.84 μm·min-1and the energy consumption is decreased from 6.30 to 4.36 k W·h·μm-1·m-2. At the same time, both mullite and amorphous Si O2 contents are decreased in the coating. 展开更多
关键词 Plasma electrolytic oxidation Eutectic Al–Si alloy Pretreatment etching
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A novel oxidation-based wet etching method for AlGaN/GaN heterostructures
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作者 蔡金宝 王金延 +5 位作者 刘洋 徐哲 王茂俊 于民 解冰 吴文刚 《Journal of Semiconductors》 EI CAS CSCD 2013年第8期201-204,共4页
A novel wet etching method for AlGaN/GaN heterojunction structures is proposed using thermal oxidation f ollowed by wet etching in KOH solution.It is found that an AlGaN/GaN heterostructure after high temperature oxid... A novel wet etching method for AlGaN/GaN heterojunction structures is proposed using thermal oxidation f ollowed by wet etching in KOH solution.It is found that an AlGaN/GaN heterostructure after high temperature oxidation above 700℃could be etched off in a homothermal(70℃) KOH solution while the KOH solution had no etching effects on the region of the AlGaN/GaN heterostructure protected by a SiO_2 layer during the oxidation process.A groove structure with 150 nm step depth on an AlGaN/GaN heterostructure was formed after 8 h thermal oxidation at 900℃followed by 30 min treatment in 70℃KOH solution.As the oxidation time increases,the etching depth approaches saturation and the roughness of the etched surface becomes much better.The physical mechanism of this phenomenon is also discussed. 展开更多
关键词 AlGaN/GaN wet etching thermal oxidation KOH solution
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Thickness-dependent patterning of MoS2 sheets with well-oriented triangular pits by heating in air 被引量:10
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作者 Haiqing Zhou Fang Yu +9 位作者 Yuanyue Liu Xiaolong Zou Chunxiao Cong Caiyu Qiu Ting Yu Zheng Yan Xiaonan Shen Lianfeng Sun Boris I. Yakobson James M. Tour 《Nano Research》 SCIE EI CAS CSCD 2013年第10期703-711,共9页
Patterning ultrathin MoS2 layers with regular edges or controllable shapes is appealing since the properties of MoS2 sheets are sensitive to the edge structures. In this work, we have introduced a simple, effective an... Patterning ultrathin MoS2 layers with regular edges or controllable shapes is appealing since the properties of MoS2 sheets are sensitive to the edge structures. In this work, we have introduced a simple, effective and well-controlled technique to etch layered MoS2 sheets with well-oriented equilateral triangular pits by simply heating the samples in air. The anisotropic oxidative etching is greatly affected by the surrounding temperature and the number of MoS2 layers, whereby the pit sizes increase with the increase of surrounding temperature and the number of MoS2 layers. First-principles computations have been performed to explain the formation mechanism of the triangular pits. This technique offers an alternative avenue to engineering the structure of MoS2 sheets. 展开更多
关键词 layered MoS2 oxidative etching thickness-dependent triangular pits
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Mechanistic insight into gold nanorod transformation in nanoscale confinement of ZIF-8
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作者 Cheongwon Bae Jaedeok Lee +5 位作者 Lehan Yao Suhyeon Park Yeonju Lee Jieun Lee Qian Chen Juyeong Kim 《Nano Research》 SCIE EI CAS CSCD 2021年第1期66-73,共8页
Core-shell hybrid nanomaterials have shown new properties and functions that are not attainable by their single counterparts.Nanoscale confinement effect by porous inorganic shells in the hybrid nanostructures plays a... Core-shell hybrid nanomaterials have shown new properties and functions that are not attainable by their single counterparts.Nanoscale confinement effect by porous inorganic shells in the hybrid nanostructures plays an important role for chemical transformation of the core nanoparticles.However,metal-organic frameworks(MOFs)have been rarely applied for understanding mechanical insight into such nanoscale phenomena in confinement,although MOFs would provide a variety of properties for the confining environment than other inorganic shells such as silica and zeolite.Here,we examine chemical transformation of a gold nanorod core enclosed by a zeolitic imidazolate framework(ZIF)through chemical etching and regrowth,followed by quantitative analysis in the core dimension and curvature.We find the nanorod core shows template-effective behavior in its morphological transformation.In the etching event,the nanorod core is spherically carved from its tips.The regrowth on the spherically etched core inside the ZIF gives rise toformation of a raspberry-like branched nanostructure in contrast to the growth of an octahedral shape in bulk condition.We attribute the shell-directed regrowth to void space generated at the interfaces between the etched core and the ZIF shell,intercrystalline gaps in mult-domain ZIF shells,and local structural deformation from the acidic reaction conditions. 展开更多
关键词 nanoscale confinement core-shell structure gold nanorod metal-organic framework oxidative etching reductive regrowth
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Increased chemical reactivity of single-walled carbon nanotubes on oxide substrates: In situ imaging and effect of electron and laser irradiations
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作者 Hasan-al Mehedi Johann Ravaux +5 位作者 Khadija Yazda Thierry Michel Said Tahir Michael Odorico Renaud Podor Vincent Jourdain 《Nano Research》 SCIE EI CAS CSCD 2016年第2期517-529,共13页
We studied the oxygen etching of individual single-walled carbon nanotubes on silicon oxide substrates using atomic force microscopy and high-temperature environmental scanning electron microscopy. Our in situ observa... We studied the oxygen etching of individual single-walled carbon nanotubes on silicon oxide substrates using atomic force microscopy and high-temperature environmental scanning electron microscopy. Our in situ observations show that carbon nanotubes are not progressively etched from their ends, as frequently assumed, but disappear segment by segment. Atomic force microscopy, before and after oxidation, reveals that the oxidation of carbon nanotubes on substrates proceeds through a local cutting that is followed by a rapid etching of the disconnected nanotube segment. Unexpectedly, semiconducting nanotubes appear more reactive under these conditions than metallic ones. We also show that exposure to electron and laser beams locally increases the chemical reactivity of carbon nanotubes on such substrates. These results are rationalized by considering the effect of substrate-trapped charges on the nanotube density of states close to the Fermi level, which is impacted by the substrate type and the exposure to electron and laser beams. 展开更多
关键词 single-walled carbon nanotubes environmental scanning electron microscopy oxidative etching substrate-trapped charges electron and laser irradiations
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Enhanced absorption of Ag diamond-type nanoantenna arrays 被引量:1
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作者 袁纵横 李骁男 +1 位作者 郭亚东 黄静 《Optoelectronics Letters》 EI 2015年第1期13-17,共5页
The optical metal nanoantenna on thin film solar cell is effective to enhance light absorption. In this paper, the diamond-type Ag nanoantenna arrays are proposed for increasing the efficiency of solar cells by locali... The optical metal nanoantenna on thin film solar cell is effective to enhance light absorption. In this paper, the diamond-type Ag nanoantenna arrays are proposed for increasing the efficiency of solar cells by localized surface plasmons resonance(LSPR). The effect of metal nanoantenna on the absorption enhancement is theoretically investigated by the finite difference time domain(FDTD) method. Broadband absorption enhancements in both visible and near-infrared regions are demonstrated in case of solar cell with diamond-type Ag nanoantennas. The spectral response is manipulated by geometrical parameters of the nanoantennas. The maximum enhancement factor of 1.51 for solar cell is obtained. For comparison, the other three nanoantennas are also analyzed. The results show that the solar cell with optimized diamond-type nanoantenna arrays is more efficient in optical absorption. 展开更多
关键词 photonic electrolyte oxidizing fabrication applying etching pores porosity specially illumination
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