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Fabrication, modification and environmental applications of TiO

S. ROHANI, T. ISIMJAN, A. MOHAMED, H. KAZEMIAN, M. SALEM, T. WANG

《化学科学与工程前沿(英文)》 2012年 第6卷 第1期   页码 112-122 doi: 10.1007/s11705-011-1144-6

摘要: Among the semiconductors, titanium dioxide has been identified as an effective photocatalyst due to its abundance, low cost, stability, and superior electronic energy band structure. Highly ordered nanotube arrays of titania were produced by anodization and mild sonication. The band gap energy of the titania nanotube arrays was reduced to 2.6 eV by co-doping with Fe, C, N atoms using an electrolyte solution containing K Fe(CN) . The photoconversion of phenol in a batch photoreactor increased to more than 18% based on the initial concentration of phenol by using a composite nanomaterial consisting of titania nanotube arrays and Pt/ZIF-8 nanoparticles. A layer-by-layer assembly technique for the deposition of titania nanoparticles was developed to fabricate air filters for the degradation of trace amounts of toluene in the air and preparation of superhyrophobic surfaces for oil-water separation and anti-corrosion surfaces.

关键词: TiO2 nanotube arrays and nanoparticles     anodization     bandgap modification     layer-by-layer deposition     oil-water separation    

SiO2 passivation layer grown by liquid phase deposition for silicon solar cell application

Yanlin CHEN,Sihua ZHONG,Miao TAN,Wenzhong SHEN

《能源前沿(英文)》 2017年 第11卷 第1期   页码 52-59 doi: 10.1007/s11708-016-0429-3

摘要: Surface passivation is one of the primary requirements for high efficient silicon solar cells. Though the current existed passivation techniques are effective, expensive equipments are required. In this paper, a comprehensive understanding of the SiO passivation layer grown by liquid phase deposition (LPD) was presented, which was cost-effective and very simple. It was found that the post-annealing process could significantly enhance the passivation effect of the LPD SiO film. Besides, it was revealed that both chemical passivation and field-effect passivation mechanisms played important roles in outstanding passivation effect of the LPD SiO film through analyzing the minority carrier lifetime and the surface recombination velocity of n-type and p-type silicon wafers. Although the deposition parameters had little influence on the passivation effect, they affected the deposition rate. Therefore, appropriate deposition parameters should be carefully chosen based on the compromise of the deposition rate and fabrication cost. By utilizing the LPD SiO film as surface passivation layer, a 19.5%-efficient silicon solar cell on a large-scale wafer (156 mm × 156 mm) was fabricated.

关键词: Si solar cell     passivation     SiO2     liquid phase deposition     carrier lifetime    

Fabrication and mechanical properties of single-wall carbon nanotubes and hyperbranched diazonium salt multilayers

LI Xinyang, FAN Pengwei, TUO Xinlin, WANG Xiaogong

《化学科学与工程前沿(英文)》 2008年 第2卷 第3期   页码 286-290 doi: 10.1007/s11705-008-0058-4

摘要: Acidized single-wall carbon nanotubes (SWNTs) were fabricated into multilayers with a hyperbranched azobenzene-containing polymeric diazonium salt (PDAS) using the layer-by-layer adsorption technique. The fabrication process, multilayer thickness variation, multilayer surface morphology and the interaction between SWNTs and PDAS were monitored by UV-Vis absorption spectroscopy, optical ellipsometry, Atomic Force Microscopy, Scanning Electron Microscopy and Raman spectroscopy. Moreover, the nanomechanical properties of the multilayer films were measured by nanoindentation. All results show that SWNTs and PDAS can be fabricated into multilayers based on the cooperation of electrostatic absorption and chemical cross-linkage between SWNTs and PDAS. Further, this cooperation endows the SWNT/PDAS multilayer films with outstanding nanomechanical properties. The hardness and modulus are about 2.0GPa and 10.0GPa, respectively. Finally, the SWNT/PDAS multilayer film can be peeled off to be a free-standing film.

关键词: PDAS     layer-by-layer     interaction     cooperation     single-wall    

无溶剂气相制备用于可持续分离过程的膜材料 Perspective

赵俊杰, Karen K. Gleason

《工程(英文)》 2020年 第6卷 第12期   页码 1432-1442 doi: 10.1016/j.eng.2020.05.002

摘要:

可用于水净化、碳捕集、生物燃料生产、燃料电池运行以及节能工业分离操作的可持续化工过程亟待发展下一代膜材料。膜的无溶剂制备不仅消除了有机溶剂的潜在环境问题,而且解决了脆弱聚合物基材的膨胀问题。此外,采用无溶剂气相沉积方法可以减少合成微孔材料[如金属有机骨架(MOF)]所需的活化步骤。本文综述了几种真空沉积工艺,包括引发式化学气相沉积(iCVD)、引发式等离子体增强化学气相沉积(iPECVD)、无溶剂气相沉积原位聚合(SLIP)、原子层沉积(ALD) 和分子层沉积(MLD)。这些无溶剂气相沉积方法在制备薄膜复合膜结构中的超薄选择层方面极具优势,而且能够保形地修饰纳米级孔道并精确调节孔径和孔内官能团。所制备的膜在气体分离、 纳滤、海水淡化和水/油分离等方面表现出颇具应用潜力的性能。因此,开发新型膜材料、放大可用于无溶剂气相沉积的高通量反应器将对化学工业产生巨大影响。

关键词: 膜分离     化学气相沉积     原子层沉积     分子层沉积     薄膜     金属有机骨架     聚合物     先进制造    

Phosphorene: Current status, challenges and opportunities

Anandarup Goswami, Manoj B. Gawande

《化学科学与工程前沿(英文)》 2019年 第13卷 第2期   页码 296-309 doi: 10.1007/s11705-018-1783-y

摘要: The field of 2-dimensional (2D) materials has witnessed a sharp growth since its inception and can majorly be attributed to the substantial technical and scientific developments, leading to significant improvements in their syntheses, characterization and applications. In the list of 2D materials, the relatively newer addition is phosphorene, which ideally consists of a single layer of black phosphorous. Keeping in mind the past, and ongoing research activities, this short account offers a brief overview of the present status and the associated challenges in the field of phosphorene-related research, with special emphasis on their syntheses, properties, applications and future opportunities.

关键词: phosphorene     black phosphorous     anisotropy     single layer     thermoelectric     chemical vapor deposition     catalysis     battery     supercapacitor    

Chemically reactive solute transfer in a boundary layer slip flow along a stretching cylinder

Swati Mukhopadhyay

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 385-391 doi: 10.1007/s11705-011-1101-4

摘要: This paper presents the distribution of a solute undergoing a first order chemical reaction in an axisymmetric laminar boundary layer flow along a stretching cylinder. Velocity slip condition at the boundary is used instead of no-slip condition. Similarity transformations are used to convert the partial differential equations corresponding to momentum and concentration into highly nonlinear ordinary differential equations. Numerical solutions of these equations are obtained by the shooting method. The velocity decreases with increasing slip parameter. The skin friction as well as the mass transfer rate at the surface is larger for a cylinder than for a flat plate.

关键词: boundary layer     stretching cylinder     partial slip     mass transfer     similarity solution    

Modeling nanostructured catalyst layer in PEMFC and catalyst utilization

Jiejing ZHANG, Pengzhen CAO, Li XU, Yuxin WANG

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 297-302 doi: 10.1007/s11705-011-1201-1

摘要: A lattice model of the nanoscaled catalyst layer structure in proton exchange membrane fuel cells (PEMFC) was established by Monte Carlo method. The model takes into account all the four components in a typical PEMFC catalyst layer: platinum (Pt), carbon, ionomer and pore. The elemental voxels in the lattice were set fine enough so that each average sized Pt particulate in Pt/C catalyst can be represented. Catalyst utilization in the modeled catalyst layer was calculated by counting up the number of facets of Pt voxels where “three phase contact” are met. The effects of some factors, including porosity, ionomer content, Pt/C particle size and Pt weight percentage in the Pt/C catalyst, on catalyst utilization were investigated and discussed.

关键词: catalyst layer     PEM fuel cell     lattice model     Monte Carlo method     catalyst utilization    

Crystallographic orientation effect on cutting-based single atomic layer removal

Wenkun XIE, Fengzhou FANG

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 631-644 doi: 10.1007/s11465-020-0599-x

摘要: The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive factors that could not be neglected in cutting at such a scale. In the present study, the crystallographic orientation effect on the cutting-based single atomic layer removal of monocrystalline copper is investigated by molecular dynamics simulation. When undeformed chip thickness is in the atomic scale, two kinds of single atomic layer removal mechanisms exist in cutting-based single atomic layer removal, namely, dislocation motion and extrusion, due to the differing atomic structures on different crystallographic planes. On close-packed crystallographic plane, the material removal is dominated by the shear stress-driven dislocation motion, whereas on non-close packed crystallographic planes, extrusion-dominated material removal dominates. To obtain an atomic, defect-free processed surface, the cutting needs to be conducted on the close-packed crystallographic planes of monocrystalline copper.

关键词: ACSM     single atomic layer removal mechanism     crystallographic orientation effect     mechanical cutting     Manufacturing III    

Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

Nabarun DEY, Aniruddha SENGUPTA

《结构与土木工程前沿(英文)》 2020年 第14卷 第6期   页码 1462-1475 doi: 10.1007/s11709-020-0674-8

摘要: Slope failure occurs due to an increase in the saturation level and a subsequent decrease in matric suction in unsaturated soil. This paper presents the results of a series of centrifuge experiments and numerical analyses on a 55° inclined unsaturated sandy slope with less permeable, stronger silty sand layer inclusion within it. It is observed that a less permeable, stronger silty sand layer in an otherwise homogeneous sandy soil slope hinders the infiltration of water. The water content of the slope just above the stronger layer increases significantly, compared to elsewhere. No shear band is found to initiate in a homogeneous sandy soil slope, whereas for a non-homogeneous slope, they initiate just above the less pervious, stronger layer. A discontinuity of the shear zone is also observed for the case of a non-homogeneous soil slope. The factor of safety of a non-homogeneous, unsaturated soil slope decreases because of the less permeable, stronger layer. It decreases significantly if this less permeable, stronger soil layer is located near the toe of the slope.

关键词: non-homogeneous slope     stronger soil layer     factor of safety     centrifuge model test     unsaturated soils    

Numerical investigation of the effectiveness of effusion cooling for plane multi-layer systems with different

Dieter BOHN, Robert KREWINKEL

《能源前沿(英文)》 2009年 第3卷 第4期   页码 406-413 doi: 10.1007/s11708-009-0041-x

摘要: Within Collaborative Research Center (SFB) 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants” at RWTH Aachen University, an effusion-cooled multi-layer plate configuration is investigated numerically by the application of a three-dimensional in-house fluid flow and heat transfer solver, CHTflow. CHTflow is a conjugate code, which yields information on the temperature distribution in the solid body. This enables a detailed discussion of the effects of a change in materials. The geometrical set-up and the fluid flow conditions derive from modern gas turbine combustion chambers and bladings. Within the SFB, two different multi-layer systems, one consisting of substrate made of CMSX-4 (a single-crystal super-alloy), an MCrAlY-bondoat and a ZrO thermal barrier coating (TBC), and the other consisting of a NiAl-alloy and a graded bondcoat/TBC, have been investigated. The grading will increase the life-span of the TBC as it can better compensate the different thermal expansion coefficients of different materials. The main focus in this study is on the different substrate materials, because the thermal conductivity of the NiAl is considerably higher than that of CMSX-4, which leads to different temperature profiles in the components. The numerical grid for the simulations contains the coolant supply (plenum), the solid body for the conjugate calculations, and the main flow area on the plate. The effusion-cooling is realized by finest drilled shaped holes with a diameter of 0.2mm. The investigation is concentrated on a cooling hole geometry with a laterally widened fan-shaped outlet, contoured throughout, and one without lateral widening that is only shaped in the TBC-region of the system. Two blowing ratios, =0.28 and =0.48, are investigated, both for a hot gas Mach number of 0.25. The results for the lower blowing ratio and the fully contoured hole are discussed as well as those of the higher blowing ratio and the non-laterally widened hole. These represent two characteristic cases.

关键词: conjugate calculation     effectiveness of effusion cooling     multi-layer systems     CMSX-4     NiAl-FG75    

The influence of manufacturing parameters and adding support layer on the properties of Zirfon

Li XU,Yue YU,Wei LI,Yan YOU,Wei XU,Shaoxing ZHANG

《化学科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 295-305 doi: 10.1007/s11705-014-1433-y

摘要: The composite separator comprising of polysulfone and zirconia was prepared by phase inversion precipitation technique. The influence of manufacturing parameters on its properties was investigated, and the results show that the manufacturing parameters affect the ionic resistance and maximum pore size significantly. A modified composite separator with a support layer was prepared to enhance the tensile strength of separator. By adding support layer, the tensile strength of the separator increases from 1.85 MPa to 13.66 MPa. In order to evaluate the practical applicability of the composite separator, a small-scale industrial electrolytic experiment was conducted to investigate the changes of cell voltage, gas purity and separator stability. The results show that the modified composite separator has a smaller cell voltage and a higher H purity than the asbestos separator, and are promising material for industrial hydrogen production.

关键词: separator     alkaline water electrolysis     manufacturing parameters     support layer    

MHD effect on the critical temperature differences of oscillatory thermocapillary convection in two-layer

Hulin HUANG, Xiaoming ZHOU,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 155-160 doi: 10.1007/s11708-009-0063-4

摘要: The effect of different directional magnetic fields on critical temperature differences of oscillatory thermocapillary convection in a rectangular cavity with differentially heated side walls filled with two viscous, immiscible, incompressible fluids is simulated in the absence of gravity. In this two-layer fluid system, the upper layer fluid is the electrically non-conducting encapsulant boron oxide (BO), while the lower one is the electrically conducting molten indium phosphide (InP). The interface between the two fluids is assumed to be flat and non-deformable. The computational results show that all the magnetic fields along the , and directions can delay the transition from steady convection to oscillatory convection, and critical temperature differences increase with an increasing Hartmann number. Furthermore, the effect of a magnetic field along the direction is strongest, followed by that along the direction, and that along the direction is the weakest for the same intensity of the magnetic field.

关键词: magnetohydrodynamic     magnetic fields     thermocapillary convection     critical temperature difference     oscillatory convection     two-layer fluid system    

Dynamic characteristics analysis of active constrained layer damping plate with various boundary conditions

Jing LU, Yu XIANG, Qiao NI

《机械工程前沿(英文)》 2011年 第6卷 第4期   页码 449-455 doi: 10.1007/s11465-011-0240-0

摘要:

Considering the direct and converse piezoelectric effect, expressions of piezoelectric membrane internal forces in the piezoelectric constrained layer were given. The control equations of the piezoelectric constrained layer and host plate were obtained in according with the thin plate theory. Based on the layer wised principle, the integrated first order differential equation of an active constrained layer damping (ACLD) plate was derived for the simply supported boundary condition. Then, this method was expanded to the ACLD plate with cantilever boundary condition by virtue of geometric analogy method. Employing the extended homogeneous capacity precision integration approach, a high precision semi-analytical method was proposed to analyze the dynamic characteristics of the ACLD plate with various boundary conditions. The comparison with the literature results has verified the accuracy and effectiveness of the present method.

关键词: active constrained layer damping (ACLD) plate     dynamic characteristics     semi-analytical method     extended homogeneous capacity precision integration approach    

Review of characterization and modeling of polymer electrolyte fuel cell catalyst layer: The blessing

Jun HUANG, Zhe LI, Jianbo ZHANG

《能源前沿(英文)》 2017年 第11卷 第3期   页码 334-364 doi: 10.1007/s11708-017-0490-6

摘要: Ionomer impregnation represents a milestone in the evolution of polymer electrolyte fuel cell (PEFC) catalyst layers. Ionomer acts as the binder, facilitates proton transport, and thereby drastically improves catalyst utilization and effectiveness. However, advanced morphological and functional characterizations have revealed that up to 60% of Pt nanoparticles can be trapped in the micropores of carbon support particles. Ionomer clusters and oxygen molecules can hardly enter into micropores, leading to low Pt utilization and effectiveness. Moreover, the ionomer thin-films covering Pt nanoparticles can cause significant mass transport loss especially at high current densities. Ionomer-free ultra-thin catalyst layers (UTCLs) emerge as a promising alternative to reduce Pt loading by improving catalyst utilization and effectiveness, while theoretical issues such as the proton conduction mechanism remain puzzling and practical issues such as the rather narrow operation window remain unsettled. At present, the development of PEFC catalyst layer has come to a crossroads: staying ionomer-impregnated or going ionomer-free. It is always beneficial to look back into the past when coming to a crossroads. This paper addresses the characterization and modeling of both the conventional ionomer-impregnated catalyst layer and the emerging ionomer-free UTCLs, featuring advances in characterizing microscale distributions of Pt particles, ionomer, support particles and unraveling their interactions; advances in fundamental understandings of proton conduction and flooding behaviors in ionomer-free UTCLs; advances in modeling of conventional catalyst layers and especially UTCLs; and discussions on high-impact research topics in characterizing and modeling of catalyst layers.

关键词: polymer electrolyte fuel cell     ultra-thin catalyst layer     electrostatic interactions     characterization and modeling     structure-property-performance relation     water management    

Bridging the gap between laboratory and field moduli of asphalt layer for pavement design and assessment

Huailei CHENG; Liping LIU; Lijun SUN

《结构与土木工程前沿(英文)》 2022年 第16卷 第3期   页码 267-280 doi: 10.1007/s11709-022-0811-7

摘要: Asphalt pavement is a key component of highway infrastructures in China and worldwide. In asphalt pavement design and condition assessment, the modulus of the asphalt mixture layer is a crucial parameter. However, this parameter varies between the laboratory and field loading modes (i.e., loading frequency, compressive or tensile loading pattern), due to the viscoelastic property and composite structure of the asphalt mixture. The present study proposes a comprehensive frequency-based approach to correlate the asphalt layer moduli obtained under two field and three laboratory loading modes. The field modes are vehicular and falling weight deflectometer (FWD) loading modes, and the laboratory ones are uniaxial compressive (UC), indirect tensile (IDT), and four-point bending (4PB) loading modes. The loading frequency is used as an intermediary parameter for correlating the asphalt layer moduli under different loading modes. The observations made at two field large-scale experimental pavements facilitate the correlation analysis. It is found that the moduli obtained via laboratory 4PB tests are pretty close to those of vehicular loading schemes, in contrast to those derived in UC, IDT, and FWD modes, which need to be adjusted. The corresponding adjustment factors are experimentally assessed. The applications of those adjustment factors are expected to ensure that the moduli measured under different loading modes are appropriately used in asphalt mixture pavement design and assessment.

关键词: asphalt mixture layer     stiffness modulus     loading mode     UC/4PB/IDT     FWD     frequency    

标题 作者 时间 类型 操作

Fabrication, modification and environmental applications of TiO

S. ROHANI, T. ISIMJAN, A. MOHAMED, H. KAZEMIAN, M. SALEM, T. WANG

期刊论文

SiO2 passivation layer grown by liquid phase deposition for silicon solar cell application

Yanlin CHEN,Sihua ZHONG,Miao TAN,Wenzhong SHEN

期刊论文

Fabrication and mechanical properties of single-wall carbon nanotubes and hyperbranched diazonium salt multilayers

LI Xinyang, FAN Pengwei, TUO Xinlin, WANG Xiaogong

期刊论文

无溶剂气相制备用于可持续分离过程的膜材料

赵俊杰, Karen K. Gleason

期刊论文

Phosphorene: Current status, challenges and opportunities

Anandarup Goswami, Manoj B. Gawande

期刊论文

Chemically reactive solute transfer in a boundary layer slip flow along a stretching cylinder

Swati Mukhopadhyay

期刊论文

Modeling nanostructured catalyst layer in PEMFC and catalyst utilization

Jiejing ZHANG, Pengzhen CAO, Li XU, Yuxin WANG

期刊论文

Crystallographic orientation effect on cutting-based single atomic layer removal

Wenkun XIE, Fengzhou FANG

期刊论文

Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

Nabarun DEY, Aniruddha SENGUPTA

期刊论文

Numerical investigation of the effectiveness of effusion cooling for plane multi-layer systems with different

Dieter BOHN, Robert KREWINKEL

期刊论文

The influence of manufacturing parameters and adding support layer on the properties of Zirfon

Li XU,Yue YU,Wei LI,Yan YOU,Wei XU,Shaoxing ZHANG

期刊论文

MHD effect on the critical temperature differences of oscillatory thermocapillary convection in two-layer

Hulin HUANG, Xiaoming ZHOU,

期刊论文

Dynamic characteristics analysis of active constrained layer damping plate with various boundary conditions

Jing LU, Yu XIANG, Qiao NI

期刊论文

Review of characterization and modeling of polymer electrolyte fuel cell catalyst layer: The blessing

Jun HUANG, Zhe LI, Jianbo ZHANG

期刊论文

Bridging the gap between laboratory and field moduli of asphalt layer for pavement design and assessment

Huailei CHENG; Liping LIU; Lijun SUN

期刊论文