RSC Advances
·
2015
·Vol. 5
·期 108
·89015-89024
·
IF 3.84
Yanqiu Pan,Wenjuan Wang,Wei Wang,Tonghua Wang
Theoretical and experimental investigations were conducted to predict particle deposition and layer growth during formation of a dynamic membrane using cross-flow microfiltration. A critical particle size model was developed and solved in radial, circumferential and axial directions by analyzing the forces acting on a single particle. The model accounted for the normal drag, lateral lift, shear-induced and Brownian diffusion forces in the depositional direction, the van der Waals force in the circumferential direction, and the cross-flow drag and van der Waals forces in the axial direction. Cross-flow velocity and feed temperature were selected as representative influencing factors to examine variations of the critical particle sizes with permeate flux. Experiments were then conducted with carbon tubes as the support and zirconium dioxide particles as the coating material to verify the model. Results showed that a dynamic layer with non-uniform thickness along the circumferential direction was formed within the horizontal tube due to gravity. The layer thickness decreased as the cross-flow velocities were increased under a given trans-membrane pressure difference and feed concentration. An appropriately large cross-flow velocity was beneficial to achieve thickness uniformity during formation. The effect of the feed temperature on the critical particle size and layer thickness can be ignored. Comparisons between the theoretical predictions and experimental data of the layer thicknesses displayed good agreements. The effects of trans-membrane pressure differences and feed concentrations were finally examined in the present work.
研究领域:
环境工程
·
化学工程
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DOI
高影响因子
Science China-Information Sciences
·
2024
·Vol. 67
·期 5
·1-9
·
IF 7.3
Liang Jieyuan,Zou Zixing,Liang Junwu,Wang Di,Wang Biao,Chu Anshi,Yi Jiali,Zhang Cheng,Fang Lizhen,Zhang Tian,Liu Huawei,Zhu Xiaoli,Li Dong,Pan Anlian
Bilayer transition metal dichalcogenides (TMDs) balance the high mobility of single layers with the high state density of multilayers and therefore have promising application prospects in high-performance electronics. However, the layer-controlled growth of 2D materials is still confronted with challenges such as poor repeatability between different labs and a limited understanding of the growth mechanism at the atomic scale. Herein, we report a new carbon-assisted chemical vapor deposition process that can realize the growth of WS 2 sheets with high yield, precise thickness controllability, and repeatability. We show that carbon can act as a reducing agent and catalyst that preferentially reacts with the WO 3 precursor to form intermediate WO 3− x products with low-valence state W. The resulting oxycarbide gas has a low surface adsorption energy when deposited on the surface of as-grown WS 2 , which provides nucleation sites for the subsequent layer of WS 2 growth and leads to the vertical growth of WS 2 sheets. The growth mechanism is thoroughly investigated. Electrical transport measurements show that the produced bilayer WS 2 possesses a high carrier mobility (up to 58 cm 2 ·V −1 ·s −1 ) and small subthreshold swing (estimated to be 148 mV/decade), which are among the best reported results for TMDs produced using CVD.
研究领域:
材料科学
·
物理化学
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DOI
高影响因子
Materials
·
2018
·Vol. 11
·期 12
·2482
·
IF 2.467
Jiaxing Sun,Xiao Zhang,Long Bai,Zhiguo Li,Zhao Jia,Jiyou Gu
A novel strategy for fabricating inverted core-shell structured latex particles was implemented to investigate the morphology and properties of polyvinyl acetate (PVAc)-based latex. In this study, active grafting points were synthesized onto the surface of PVAc latex cores via grafting acrylonitrile (AN) to obtain a controllable coating growth of the shell monomer, styrene (St). The effect of shell growth on the morphological evolvement was explored by tuning the time of shell monomer polymerization. Unique particle morphologies, transferring from “hawthorn” type, over “peeled pomegranate” type, to final “strawberry-like” type, were observed and verified by electron microscopy. The morphological structure of latex particles exerted a significant effect on the particle size, phase structure, and mechanical properties of the obtained emulsions. The water-resistance of PVAc-based latex was also evaluated by the water absorption of latex films. More importantly, the experimental results provided a reasonable support for the controlled growth of St monomer, that is, the self-nucleation of dispersive St monomer can be transformed to in-situ coating growth on the PVAc core surface depending on the AN-active grafting points. This fabricating approach provides a reference for dynamical design and control of the latex particle morphology.Keywords:inverted core-shell particle;polyvinyl acetate;acrylonitrile grafting;shell growth;morphological evolution
研究领域:
材料科学
·
高分子化学
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DOI
PubMed
高影响因子
Scientific Reports
·
2016
·Vol. 6
·期 1
·1-10
·
IF 5.228
Zhang Jian,Zhang Qiaoxia,Wang Lianhui,Li Xing’ao,Huang Wei
A model of interface induction for interlayer growing is proposed for bandgap engineering insights into photocatalysis. In the interface of CdS/ZnS core/shell nanorods, a lamellar solid solution intermediate with uniform thickness and high crystallinity was formed under interface induction process. Merged the novel charge carrier transfer layer, the photocurrent of the core/shell/shell nanorod (css-NR) array was significantly improved to 14.0 mA cm −2 at 0.0 V vs. SCE, nearly 8 times higher than that of the perfect CdS counterpart and incident photon to electron conversion efficiency (IPCE) values above 50% under AM 1.5G irradiation. In addition, this array photoelectrode showed excellent photocatalytic stability over 6000 s. These results suggest that the CdS/Zn 1−x Cd x S/ZnS css-NR array photoelectrode provides a scalable charge carrier transfer channel, as well as durability and therefore is promising to be a large-area nanostructured CdS-based photoanodes in photoelectrochemical (PEC) water splitting system.
研究领域:
材料科学
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光催化
·
纳米技术
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DOI
PubMed
高影响因子
Coatings
·
2025
·Vol. 15
·期 2
·177
·
IF 2.8
Zijian Mo,Zupeng Mo,Kaisen Guo,Zhiyun Yu,Huan He,Tianquan Liang
Calcium–magnesium–alumina–silicate (CMAS), as an environmental deposit, deposits on engine components and causes serious damage to traditional thermal barrier coatings (TBCs) at high temperatures. The rare-earth silicate apatite dense reaction layer is regarded as a promising strategy to prevent TBCs from molten CMAS penetration and corrosion. The interactions between the Gd2O3ceramic and CMAS are discussed at various temperatures and times in the study. The main reaction products are gadolinium silicate apatite (Ca2Gd8(SiO4)6O2, Gd-apatite) and melilite phases. Within the first 15 min of interaction, a thin, continuous and dense reaction layer (DRL) consisting of Gd-apatite comes to form, and it thickens with increasing exposure temperature and time. The thickness of the DRL is ~0.8 μm after 15 min of the reaction at 1250 °C and it slowly increases to ~9.1 μm after a duration of 24 h at 1400 °C. This is attributed to CMAS infiltration along the grain boundaries of the Gd-apatite phases in the DRL. The growing rates of the Gd-apatite DRL decrease with reaction time and are significantly influenced by the temperature and the ability of the DRL to inhibit CMAS infiltration.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
Nanoscale
·
2020
·Vol. 12
·期 6
·3715-3722
·
IF 6.895
Long Fang,Xiaoming Yuan,Kunwu Liu,Lin Li,Peng Zhou,Wei Ma,Han Huang,Jun He,Shaohua Tao
Homo-junction and multi-layer structures of transition metal chalcogenide (TMD) materials provide great flexibility for band-structure engineering and designing photoelectric devices. However, the knowledge of van der Waals epitaxy growth limits the development of these heterostructures. Herein, we employed the chemical vapor deposition (CVD) growth strategy to synthesize novel WSe2 homo-junction samples with a triangular monolayer in the center and three AA stacking bilayer flakes connected to the vertexes of the monolayer. The emitted photon energy from the bilayer near the junction showed a blueshift in energy of up to 24 meV compared with bare bilayer WSe2, confirming the charge transfer effect from monolayer to bilayer WSe2. Further growth studies revealed the shape evolution from WSe2 homo-junction to bilayer. The whole homo-junction formation and evolution process cannot be explained by the traditional layer-by-layer growth mechanism. Instead, a direct bilayer growth approach is proposed to explain the bilayer formation and evolution at the vertexes of the bottom layer of WSe2. These findings suggest that the growth of bilayer TMDs is more complex than our previous understanding. This work presents deepens insight into van der Waals epitaxy growth, and thus is valuable for guiding the fabrication of novel homo-junctions for both fundamental science and optoelectronic applications.
研究领域:
材料科学
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光电应用
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DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2024
·
IF 8.1
Yinghui Fan,Wenqing Wang,Abdul Haleem,Jianming Pan,Hao Li
Creating uniform magnetic covalent organic framework (MCOF) adsorbents for effectively capturing and separating gold presents a considerable challenge. However, achieving this uniformity is crucial for resource recycling and environmental protection. This study introduces a monomer-mediated in situ layer-by-layer growth strategy employing a timed injection method for fabricating magnetic covalent organic frameworks. The hybrid MCOFs produced, Fe 3 O 4 @SiO 2 @COF and Fe 3 O 4 @SiO 2 @COF-DMSA, possess abundant binding sites that enhance adsorption capacities, rapid kinetics, and remarkable regeneration performance for gold recovery. Significantly, the Fe 3 O 4 @SiO 2 @COF exhibits a lower gold adsorption capacity (898 mg g −1 ), whereas Fe 3 O 4 @SiO 2 @COF-DMSA exhibits an improved Au (III) selectivity and a larger capacity for adsorption (1116 mg g −1 ). The capturing mechanism of Au (III) by Fe 3 O 4 @SiO 2 @COF-DMSA is predominantly attributed to coordination and reduction, as identified through XPS analysis. This study motivates conceptualizing molecular/ionic capture strategies using core–shell NP/COF hybrid materials to retrieve precious metals.
研究领域:
材料科学
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环境科学
·
化学工程
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产品关联
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2023
·Vol. 33
·期 34
·2301815
·
IF 19
Yunpeng Zheng,Hetian Chen,Zhifang Zhou,Yueyang Yang,Mingchu Zou,Wenyu Zhang,Bin Wei,Jinghan Cai,Jin-Le Lan,Di Yi,Ce-Wen Nan,Yuan-Hua Lin
Thermoelectric oxide thin films are promising in chip cooling. The issues on the orientation of thin films are essential as they are related to the structures, morphologies, and thermoelectric properties. In this regard, the orientation modulation is conducted on La-doped SrTiO 3 thin films on (LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 (LSAT) single crystal substrates. Layer-by-layer growth mode is found in (001)- and (110)- oriented thin films, resulting in few grain boundaries (GBs). In (111)-oriented films, island growth mode leads to columnar grain boundaries that build up potential barriers for electrons to be strongly scattered and filtered, suppressing electron mobility and increasing effective mass. In addition, the GBs serve as oxygen vacancy diffusion paths when annealing, causing increased carrier concentration and lattice contraction. The weighted mobility of 71.9 cm 2 V −1 s −1 and electrical conductivity of ≈600 S cm −1 are realized in the (001)-oriented film at room temperature. Ultimately, outstanding power factor values of ≈569 µW m −1 K −2 (room temperature) and ≈791 µW m −1 K −2 (573 K) are successfully achieved, outperforming those in polycrystalline ceramics and (111)-oriented films. This study systematically investigates the influence of grain boundaries and orientations on SrTiO 3 -based thermoelectric films, which lays a solid foundation for improving thermoelectric performance in other oxide thin films.
研究领域:
材料科学
·
热电学
·
薄膜
·
固体物理学
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DOI
高影响因子
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