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Full-Text Articles in Engineering Science and Materials
Recent Advances In Bismuth-Based Co2 Reduction Electrocatalysts, Rui Zhou, Na Han, Yan-Guang Li
Recent Advances In Bismuth-Based Co2 Reduction Electrocatalysts, Rui Zhou, Na Han, Yan-Guang Li
Journal of Electrochemistry
Carbon dioxide (CO2) is an economical, secure and sustainable carbon resource around us. Its effective capture and recycling have been the focus of our entire society. Using the electrochemical method, CO2 can be reduced to different value-added chemicals or fuels. This approach not only would mitigate CO2 accumulation in the atmosphere, but also would help alleviate our dependence on fossil fuel. In this article, the basic principle and process of electrochemical CO2 reduction are first introduced. The recent development in bismuth-based catalysts for electrocatalytic CO2 reduction is reviewed with an emphasis on their preparation, …
Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang
Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang
McKelvey School of Engineering Theses & Dissertations
Cellulose is biodegradable, renewable, and abundant in nature thus cellulose (or paper)-based products can be inexpensively produced and recycled. Among cellulosic materials, bacterial nanocellulose (BNC) draws a special research attention due to the inherent three-dimensional nanofibrous structure, excellent mechanical flexibility, high purity and well-defined surface chemistry, and cost-efficient, scalable and environment-friendly synthesis. BNC can be biosynthesized by Gluconacetobacter xylinus, which is the most characterized BNC producer among various microorganisms. BNC is composed of highly pure cellulose nanofibrils, produced from well-defined dextrose through biochemical steps and subsequent self-assembling of the secreted cellulose fibrils which has the dimension ranges from 25 to …
Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang
Multifunctional Nanocomposites Based On Bacterial Cellulose, Qisheng Jiang
McKelvey School of Engineering Theses & Dissertations
Cellulose is biodegradable, renewable, and abundant in nature thus cellulose (or paper)-based products can be inexpensively produced and recycled. Among cellulosic materials, bacterial nanocellulose (BNC) draws a special research attention due to the inherent three-dimensional nanofibrous structure, excellent mechanical flexibility, high purity and well-defined surface chemistry, and cost-efficient, scalable and environment-friendly synthesis. BNC can be biosynthesized by Gluconacetobacter xylinus, which is the most characterized BNC producer among various microorganisms. BNC is composed of highly pure cellulose nanofibrils, produced from well-defined dextrose through biochemical steps and subsequent self-assembling of the secreted cellulose fibrils which has the dimension ranges from 25 to …
Implementation Of New System For Oxygen Generation And Carbon Dioxide Removal, Angelo Peter Karavolos
Implementation Of New System For Oxygen Generation And Carbon Dioxide Removal, Angelo Peter Karavolos
Open Access Theses & Dissertations
This research effort develops an integrated system for CO2 removal and O2 production. A unique material, dodeca-tungsto-phosphoric acid (H3PO4W12O3; henceforth referred to as DTPA) is mixed with tetra-ethyl-ortho-silicate Si(OC2H5)4 or TEOS. This mixture exhibits unique properties of heat absorption and high electrical conductivity. In the system described herein, the DTPA resides within a cross linked arrangement of TEOS. The DTPA furnishes a source of O2, while the TEOS furnishes structural support for the large DTPA crystals. In addition, the large amount of H2O within the crystal also adsorbs CO2. It can also be cross-linked with other polymers such as polycarbonate, …
The Analysis Of The Tribological Properties Of Multiple Strengthened Nanocomposite Of The Cu-Al2o3 System, Zeljko J. Kamberovic
The Analysis Of The Tribological Properties Of Multiple Strengthened Nanocomposite Of The Cu-Al2o3 System, Zeljko J. Kamberovic
Zeljko J Kamberovic
This paper presents the results of examined tribological properties of the multiple strengthened nanocomposite Cu-Al2O3 system. Cu-Al2O3 composite powder was obtained by combination of the thermo-chemical procedure and mechanical alloying, which is a completely new approach to synthesis of these materials. The synthesized powders were cold pressed with 940MPa and sintered in hydrogen atmosphere in temperature range of 725-925o C during 15-120 minutes. The samples were thermo- mechanically treated in two stages after sintering: cold rolling with the final reduction degree of 30% and annealing at 800o C for 1h in hydrogen atmosphere. Characterization of the sintered, rolled and annealed …
Effect Of Concentration On Electrospun Polyacrylonitrile (Pan) Nanofibers, Ji-Huan He, Yu-Qin Wan, Jian-Yong Yu
Effect Of Concentration On Electrospun Polyacrylonitrile (Pan) Nanofibers, Ji-Huan He, Yu-Qin Wan, Jian-Yong Yu
Ji-Huan He
Abstract: An allometrical scaling relationship between the diameter of electrospun nanofiber and solution concentration is established, the scaling exponent differs greatly between different polymers and the same polymer with different molecules or the same molecules with different properties. The diameter of electrospun polyacrylonitrile (PAN) nanofibers increases approximately linearly with solution concentration.
Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic
Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic
Zeljko J Kamberovic
This paper is a contribution to characterization of Cu-Al2O3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.
Determination Of Al2o3 Particle Size In Cu-Al2o3 Nanocomposite Materials Using Uv Spectrophotometry, Zeljko J. Kamberovic
Determination Of Al2o3 Particle Size In Cu-Al2o3 Nanocomposite Materials Using Uv Spectrophotometry, Zeljko J. Kamberovic
Zeljko J Kamberovic
In order to achieve improved mechanical properties of dispersion strengthened nanocomposite, without influencing electrical and thermal conductivity it is necessary for dispersoide to be nano sized and uniformly distributed in base metal matrix. In this paper are presented the results concerning possibility of using UV spectrophotometry for determination of alumina particle size in Cu-Al2O3 system. Presented results show that this method is unefficient as method for determination of dispersoide particle size, due to the coalescence of particles false results are obtained, i.e. particle size significantly higher then one determined by image analysis.
Sintering Of Cu–Al2o3 Nano-Composite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Sintering Of Cu–Al2o3 Nano-Composite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Zeljko J Kamberovic
This paper presents the synthesis of nano-composite Cu–Al2O3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu–Al2O3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA–TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20–50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by …
Synthesis And Sintering Of Cu-Al2o3 Nanocomposite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Synthesis And Sintering Of Cu-Al2o3 Nanocomposite Powders Produced By A Thermochemical Route, Zeljko J. Kamberovic
Zeljko J Kamberovic
By hydrometallurgy and powder metallurgy along with prognosis of physical- chemical properties, a synthesis of new improved materials can be successfully performed with in advance pre-set properties which is conditioned by a quality of starting powders i.e. by improving their structure. In accordance with that, this paper presents synthesis of the nanocomposite Cu-Al2O3 powder by thermochemical method and sintering with a comparative analysis of the mechanical and electrical properties of obtained solid samples. Nanocrystaline Cu-Al2O3 powders were produced by thermochemical method through following stages: spray-drying, oxidation of precursor powder, reduction by hydrogen and homogenisation. Characterization of powders included differential-thermal and …
Bubble Electrospinning For Mass Production Of Nanofibers, Yong Liu, Ji-Huan He
Bubble Electrospinning For Mass Production Of Nanofibers, Yong Liu, Ji-Huan He
Ji-Huan He
A new bottom-up gas-jet electrospinning process for mass production is presented. A bubble-induced cone on the surface of polymer solution is equivalent to the Taylor cone in traditional electrospinning, which is a must for producing nanofibers. In this study bubbles are produced by compressed air or nitrogen through a nozzle settled in the bottom of the solution. Multiple jets are observed during the electrospinning process as predicted for it is easy to many bubble-induced cones on the solution surface. The new electrospinning mechanism can be used for mass production of nanofibers.
The Synthesis Of Ultrafine And Nanocomposite Powders Based On Copper, Silver And Alumina, Zeljko J. Kamberovic
The Synthesis Of Ultrafine And Nanocomposite Powders Based On Copper, Silver And Alumina, Zeljko J. Kamberovic
Zeljko J Kamberovic
Contemporary materials with predetermined properties can be successfully synthesized by utilising the principles of hydrometallurgy and powder metallurgy. The results of developing a new procedure for the synthesis of ultrafine and nanocomposite powders based on copper, silver and alumina are presented in this paper. A two-component nanocomposite powder, Cu-Al2O3, was synthesized by a thermochemical procedure, by deposition from an aqueous solution of soluble metal salts, Cu(NO3)2 and Al(NO3)3. A three-component Cu-Ag-Al2O3 powder was produced by mechanically alloying nanocomposite Cu-Al2O3 powder and Cu-Ag powder, synthesized by the thermochemical procedure. The produced powders were characterized by determining the particle specific area, pouring …