Engineering Science and Materials Commons^™

Experimental And Numerical Investigation On The Irregularity Of Carbonation Depth Of Concrete Under Supercritical Condition, Hao Bao Masc, Min Yu Dr., Jianqiao Ye Dr., Lihua Xu Dr., Yin Chi Dr., J Ye

International Conference on Durability of Concrete Structures

The heterogeneity of a cement-based material results in a random spatial distribution of carbonation depth, which may significantly affect the mechanical properties and durability of the material. Currently, there is a lack of both experimental and numerical investigations aiming at a statistical understanding of this important phenomenon. This paper presents both experimental and numerical supercritical carbonation test results of concrete blocks. The random fields of porosity and two-dimension random aggregate model of concrete were proposed for the simulation. The carbonation depths are measured and distributed along the carbonation boundary by the proposed rapid image processing technique, which are then statistically …

Alkali Reactive Carbonate Rocks: Is It Alkali Silica Reaction (Asr) Or Alkali Carbonate Reaction (Acr)?, Mengesha Beyene, Rc Meininger

International Conference on Durability of Concrete Structures

The root cause of distress in two different concrete structures made from carbonate coarse aggregates that fit the textural and compositional criteria cited for ACR was found to be caused by ASR, not ACR. Stereo-optical examination and transmitted polarized light microscopy (PLM) analysis showed that the concretes contain some dark gray, fine-grained argillaceous dolomitic coarse aggregates in which secondary white deposit filling the cracks extending from these aggregates into the paste (as well as lining air voids) is ASR gel. Back scattered electron (BSE) imaging with EDS spectra and x-ray elemental mappings, clearly confirm that the white secondary deposits consist …

Three-Dimensional Porous Vn Octahedron Catalyst With High Electrocatalytic Efficiency Toward Hydrogen Evolution Reaction, Can Yin, Wei-Wei Fu, Ling Fang, Shi-Li You, Hui-Juan Zhang, Yu Wang

Journal of Electrochemistry

With the rapid development of China’s economy, the demand for energy is increasing, and environmental problems are becoming more and more serious. The development and utilization of highly-clean new energy fuel can effectively alleviate the energy crisis and environmental pollution. Nowadays, exploring high-efficiency, environment-friendly and low-cost catalysts remains the focus of research in the hydrogen evolution reaction (HER). In this research, firstly, we proposed a three-dimensional porous vanadium nitride (VN) with octahedral structure, which was prepared by a calcination treatment method. The VN catalyst showed a good electrocatalytic activity toward HER, involving a small overpotential of 94.0 mV at -10 …

Influences Of Morphology And Nitrogen Doping On The Electrocatalytic Characteristics For Oxygen Reduction Reaction Of Nio/Rgo, Dong Liang, Heng-Yi Fang, Shuo Yao, Jie-Mei Yu, Zhao-Liang Zhang, Zhan-Kun Jiang, Xue-Ping Gao, Tai-Zhong Huang

Journal of Electrochemistry

In this research, the reduced graphene oxide (rGO) supported sheet-like NiO (NiO/rGO) and spherical-like NiO (NiO/N-rGO) catalysts for oxygen reduction reaction (ORR) were prepared. The structures, morphologies and chemical states of the two catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical catalytic performance of the two catalysts for ORR were investigated by cyclic voltammetry (CV), Tafel, linear sweeping voltammetry (LSV), rotating disc electrode (RDE) and rotating ring disc electrode (RRDE) tests. Electrochemical results showed that the current density and onset potential (about 0.89 V) …

Preparation Of Nanostructural Mno-Porous Graphene Hybrid Material By Thermally-Driven Etching Of Mno For Lithium-Air Batteries, Juan Yang, Jun-Wei Lang, Peng Zhang, Bao Liu

Journal of Electrochemistry

In this paper, improving the surface morphology of graphene(GNSs) as designed concept. we describe a MnO/porous-graphene(MnO-PGNSs) was synthesized by a simple site-localized Mn²⁺ on GO (Mn-GO) by charge adsorption and then driving by high-temperature calcination, growing MnO nanoparticles and etching GNSs achieved on step. And Then focus on the key factors of influenced the etch hole formation are analyzed, founded the dispersion of Mn-GO; layer number of GO and calcination temperature also affected the formation of holes. In addition, the MnO-PGNSs as lithium-air battery cathode exhibits high reversible capacity compared with GNSs and PGNs and it is able to …

Special Issue: Electrocatalysis And Fuel Cells, Shuangyin Wang

Journal of Electrochemistry

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A Facile Route To Synthesize Pt-Wo3 Nanosheets With Enhanced Electrochemical Performance For Her, Peng-Jie Jiang, Yi Lv, Chang-Miao Chen, Hong-Cheng He, Yong Cai, Ming Zhang

Journal of Electrochemistry

Platinum-tungsten trioxide (Pt-WO₃) nanosheets were synthesized on nickel foams (NFs) directly. As great conductive networks, NFs substrates could greatly improve the electrode performance of WO₃. The modified platinum nanoparticles not only enhanced the electron transformation of catalysts, but also increased the active sites for hydrogen evolution reaction (HER). Pt-WO₃/NF revealed a better catalytic activity than WO₃/NFs with a smaller Tafel slope (80 mV·dec^-1) and a lower overpotential of 72 mV at the current density of 10 mA·cm^-2. In addition, Pt-WO₃/NF showed great durability and stability during …

Nickel Selenide Derived From [Ni(En)3](Seo3) Complex For Efficient Electrocatalytic Overall Water Splitting, Dan-Dan Chen, Xue-Qing Gao, Hong-Fei Liu, Wei Zhang, Rui Cao

Journal of Electrochemistry

Electrocatalytic water splitting is considered as a promising technology for renewable energy. The development of efficient, stable, cost-effective, and bifunctional catalysts for both water reduction and oxidation has continued to face significant challenges. Herein, we report a robust and highly active nickel selenide (NiSe) spheres grown on carbon cloth (CC) by electrodeposition from a nickel selenite complex which is a single source containing both Ni and Se. A combination of two chemicals containing, separately, Ni and Se is used in traditional preparations of metal selenides, causing possible problems in the uniformity of the products. The as-prepared NiSe-EA/CC electrode exhibited electrocatalytic …

Pd Nanoparticles Supported On The Etched Ni Foams As High-Performance Electrocatalysts For Direct Ethanol Fuel Cells, Chi Zhang, Cheng-Fei Li, Gao-Ren Li

Journal of Electrochemistry

The development of non-Pt anode electrocatalysts with high activity and long-term durability at low cost for fuel cells still remains enormous challenge. Here we report the Pd nanoparticles supported on Ni foams etched by the mixed acids (HNO₃+H₂SO₄+H₃PO₄+CH₃COOH) (Pd/ME-NF) that are designed and fabricated as high-performance electrocatalysts for ethanol oxidation in alkaline media. Because of the advantages of large open space, fast electrolyte penetration/diffusion and rapid electron transfer process, the Pd/ME-NF catalysts exhibited significantly improved electrocatalytic activity and durability compared with the commercial Pd/C catalysts.

Investigations In Electrochemical Thermodynamic And Kinetic Properties Of As-Cast And As-Quenched Cemg10Ni2 Hydrogen Storage Alloys, Feng Hu, Li-Rong Luo, Yong-Zhi Li, Ting-Ting Zhai, Xin Zhao, Yang-Huan Zhang

Journal of Electrochemistry

In order to improve the electrochemical hydrogen storage properties of CeMg₁₀Ni₂ alloy, the rapid quenching technology was used to prepare CeMg₁₀Ni₂ alloys with nano-crystalline and amorphous structure. The microstructures of as-cast and as-spinning sample were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical hydrogen storage properties were investigated by an automatic galvanostatic charging/discharging, high rate discharging (HRD), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results revealed that the as-cast alloy was composed of multiphase structures. The as-quenched alloys were made up of nano-crystalline and/or amorphous structures, and the …

Regulation Of Copper Surface Via Redox Reactions For Enhancing Carbon Dioxide Electroreduction, Bao-Hua Hang, Jin-Tao Zhang

Journal of Electrochemistry

A large-scale application of fossil fuels has led to excessive emission of carbon dioxide (CO₂), resulting in serious environmental issues. A promising path to reducing CO₂ emissions is recycling CO₂ into valuable chemicals and fuels through an electrochemical process. Herein, the redox reactions between copper (Cu) and ferric chloride (FeCl₃) have been utilized to regulate the Cu surface composition and structure, aimed to improve the electrocatalytic activity toward CO₂ reduction. Typically, a series of samples (named Cu-1h, Cu-2h, Cu-3h and Cu-4h) were prepared via the redox reactions for various time from 1 to …

Single-Layer Oxygen Deficiency Δ-Mno2 For Electrochemical Co2 Reduction, Yue-Feng Zhang, Jian-Jun Liu, Zeng-Xi Wei, Xin-Xin Tian, Jian-Min Ma

Journal of Electrochemistry

Manganese dioxide (MnO₂) has been widely used in catalysis. In addition, since the defect engineering can change the electronic properties of the catalyst, here we have systematically studied electrocatalytic carbon dioxide reduction reaction (CO₂RR) on δ-MnO₂ with and without oxygen deficiency, denoted as Ov-MnO₂ and MnO₂, respectively. We calculate the electronic properties and the intermediate of free energy for MnO₂ and Ov-MnO₂ with the help of spin-polarized density functional theory. By analyzing this result, we can find that the introduction of defects change the δ-MnO₂ from semiconducting properties to …

Statuses, Challenges And Strategies In The Development Of Low-Temperature Carbon Dioxide Electroreduction Technology, Xu-Rui Zhang, Xiao-Lin Shao, Jin Yi, Yu-Yu Liu, Jiu-Jun Zhang

Journal of Electrochemistry

Low-temperature carbon dioxide (CO₂) electrochemical reduction technology is a hotspot for research and development in recent years as a way to reduce the negative impact of CO₂ on the environment and to generate energy storage through converting electricity to low-carbon fuels. Although basic research on catalyst activity, product selectivity, and reaction mechanism has been widely reported, the design and practicality of catalytic stability and corresponding electrochemical reactor systems have not been given sufficient attention and systematic development.  In this paper, two important factors affecting the development of CO₂ electrochemical reduction technology in low temperature aqueous solution …

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, …

Electrocatalytic Reduction Of Carbon Dioxide To Carbon Monoxide Using Cobalt Nitride, Chen Ma, Peng-Fei Hou, Peng Kang

Journal of Electrochemistry

Electrocatalytic reduction of carbon dioxide (CO₂) is a promising method to alleviate global warming issues, although it still faces many challenges. Herein, we report cobalt nitride for electrocatalytic reduction of CO₂ to carbon monoxide (CO) in an aqueous electrolyte. A comparison of catalysts with different preparation temperatures and atmospheres suggests that nitrogen doping is critical to improve catalytic activity. For the most active catalyst of 700-Co_5.47N/C, the CO current density reached 9.78 mA·cm^-2 at potential of -0.7 V vs. RHE. In addition, the CO/H₂ ratio could be adjusted from 1:3 to 3:2 by …

Effect Of Morphology Of Fe-N Codoped Carbon Nanomaterial On Electrochemical Reduction Reactions, Er-Ling Li, Fa Yang, Ming-Bo Ruan, Ping Song, Wei-Lin Xu

Journal of Electrochemistry

Graphene nanosheets (GS) and carbon nanotubes have been considered as good catalysts candidates for applications in energy conversion and storage. However, hybrids of GS and carbon nanotubes are always formed in transition metal-based nitrogen-doped system, making the system quite complex for exploring the structure-activity relationship. To prepare the catalysts with desired species controllably, we try to adjust the outcomes with the effect of nitrogen on the growth of carbon nanotubes. In this work, a series of Fe-N co-doped carbon hybrid catalysts containing N-doped GS or hybrids of GS/bamboo carbon nanotubes (BCNTs) or BCNTs were obtained with one-step pyrolyzed method. To …

Electrochemical Detection Of 4-Nitrophenol Based On Glassy Carbon Electrode Modified By Tio2Nps/Rgo Composite, Lin-Na Jiu, Yong-Qiang Cheng

Journal of Electrochemistry

4-nitrophenol (4-NP) has become factitious pollution, and presented a serious threat to the nature and human health. It is necessary to develop a convenient and fast detection method. In this work, the glassy carbon electrode modified by titanium dioxide nanoparticles (TiO₂NPs)/reduced graphene oxide (RGO) composite as an electrochemical sensor was studied for the trace detection of 4-NP. The morphology of the composite was characterized by scanning electron microscopy (SEM). The homogeneous mixing of titanium dioxide nanoparticles and reduced graphene oxide increased the specific surface area of the composite, and facilitated the electrochemical reaction of 4-NP. The electrochemical characteristics …

Preparations And Electrocatalytic Properties Of Cu-Bipy-Btc-Derived Carbon-Based Catalyst For Oxygen Reduction Reaction, Li-Hua Zhang, Jun-Feng Chen, Wan-Tang Huang, Yong-You Hu, Jian-Hua Cheng, Yuan-Cai Chen

Journal of Electrochemistry

Efficient and low-cost oxygen reduction reaction (ORR) electrocatalyst plays a key role for fuel cells. In this paper, ORR active metal organic framework (MOF: Cu-bipy-BTC, bipy = 2,2?-bipyridine, BTC = 1,3,5-tricarboxylate) was prepared using hydrothermal method, and then carbon-based material MOF-800 was obtained from pyrolyzing Cu-bipy-BTC at 800 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption isotherm and X-ray photolectron spectroscopy (XPS) were used to characterize the morphologies and structures of the catalysts. Linear sweep voltammetry (LSV) and current-time curve (i-t) were adopted to evaluate the electrocatalytic properties of the catalysts. The results …

Abrasion Resistance Of High Early-Strength Concrete For Rapid Repair, Nader Ghafoori, Matthew O. Maler, Meysam Najimi, Ariful Hasnat

Civil and Environmental Engineering and Construction Faculty Research

This paper examines the abrasion resistance of high early-strength concrete developed for rapid repair of highways and bridge decks. The cement types chosen for this study included ASTM Type III, ASTM Type V, and Calcium Sulfoaluminate (CSA) cements. A cement content of 386 kg/m3 (650 lb/yd3 ) was maintained for all studied concretes. Test samples were tested after 24 hours and 28 days of curing in order to evaluate compressive strength and depth of wear. Test results revealed that the opening time to attain minimum required compressive strength for CSA cement concrete was one hour, whereas the values for Type …

Preface To Special Issue Of Electrochemical Reduction Of Carbon Dioxide, Qing Li, Min Liu

Journal of Electrochemistry

No abstract provided.

Copper-Based Compounds For Electrochemical Reduction Of Carbon Dioxide, Fan Yang, Pei-Lin Deng, You-Jia Han, Pan Jing, Bao-Yu Xia

Journal of Electrochemistry

The electrochemical reduction of carbon dioxide (CO₂) to useful chemicals and fuels has attracted enormous interest since the deteriorating global warming and energy shortage problems resulted from ever-increasing CO₂ emission. Designing efficient catalysts is of capital significance to realize the efficient and selective conversion of CO₂. Among various catalysts explored, copper-based compounds have promising potentials with acceptable efficiency for hydrocarbon production. Herein, recent advances on copper-based materials are summarized for electrochemical CO₂ conversion. We intend to include the dimensional structure, different forms (alloy, oxide) and molecular catalysts in copper-based catalysts. Moreover, the reaction mechanisms …

Recent Progress In Copper-Based Catalysts For Electrochemical Co2 Reduction, Wen Lei, Wei-Ping Xiao, De-Li Wang

Journal of Electrochemistry

As the situation of energy crisis and environmental pollution become more and more serious, the electrochemical reduction of carbon dioxide (CO₂) has attracted lots of attention because of its multiple meanings such as environment, resources and economic benefits. In this paper, the state of the art electrochemical reduction of CO₂ in aqueous solution is reviewed, and the latest research progress in Cu-based catalysts with different structures and morphologies is summarized. In the end, the application prospects, opportunities and challenges of Cu-based materials are briefly presented to provide an outlook for future research directions.

Rheological Properties Of Modified Crumb Rubber Asphalt Binder And Selecting The Best Modified Binder Using Ahp Method, Mehdi Khalili, Kazem Jadidi, Moses Karakouzian, Serji Amirkhanian

Civil and Environmental Engineering and Construction Faculty Research

Crumb rubber modifier (CRM) is one of the most popular asphalt binder modifiers due to the economic benefits and desired physical and rheological properties of asphalt binders and asphalt mixes. This research focuses on evaluating the properties of rubber-modified asphalt binders and selecting the best modified binder. The modified binders were produced by blending virgin binders with CRM at various contents of different gradations, and different methods of grinding. CRM made through ambient and cryogenic grinding methods with two gradation sizes were produced and tested. Three different virgin binders from two sources were obtained and used. The Analytic Hierarchy Process …

Development Of Experimental And Finite Element Models To Show Size Effects In The Forming Of Thin Sheet Metals, Jeffrey D. Morris

LSU New Orleans Theses and Dissertations

Abstract

An experimental method was developed that demonstrated the size effects in forming thin sheet metals, and a finite element model was developed to predict the effects demonstrated by the experiment. A universal testing machine (UTM) was used to form aluminum and copper of varying thicknesses (less than 1mm) into a hemispherical dome. A stereolithography additive manufacturing technology was used to fabricate the punch and die from a UV curing resin. There was agreement between the experimental and numerical models. The results showed that geometric size effects were significant for both materials, and these effects increased as the thickness of …

General Nonlinear-Material Elasticity In Classical One-Dimensional Solid Mechanics, Ronald Joseph Giardina Jr

LSU New Orleans Theses and Dissertations

We will create a class of generalized ellipses and explore their ability to define a distance on a space and generate continuous, periodic functions. Connections between these continuous, periodic functions and the generalizations of trigonometric functions known in the literature shall be established along with connections between these generalized ellipses and some spectrahedral projections onto the plane, more specifically the well-known multifocal ellipses. The superellipse, or Lam\'{e} curve, will be a special case of the generalized ellipse. Applications of these generalized ellipses shall be explored with regards to some one-dimensional systems of classical mechanics. We will adopt the Ramberg-Osgood relation …

Microstructural Effects On Photocatalytic Performance In Ag3po4/Bi2moo6 Z-Scheme Photocatalyst Systems, Kaleab Mengesha Ayalew

UNLV Theses, Dissertations, Professional Papers, and Capstones

As the world population continues to grow and access to modern industry become increasingly common, humanity finds itself amid an environmental and energy crisis. Natural resources, such as clean water are getting scarce. Currently, the development of high efficiency, green energy sources, and eco-friendly methods for water treatment have become a nonelective task. As a result, photocatalysis, as one of the most promising technologies in utilizing solar energy and pollutant removal, has attracted considerable attention.

However, the practical application of photocatalysis is still elusive because of the difficulty of finding an individual material that can satisfy all the requirements for …

Preparation Of Chitosan-Polyethylene Oxide-Colocasia Esculenta Flour Nanofibers Using Electrospinning Method, Riesca Ayu Kusuma Wardhani, Lia Asri, Muhamad Nasir, Bambang Sunendar Purwasasmita

Journal of Mechanical Engineering Science and Technology (JMEST)

Nanofibers have been prepared from the mixture of chitosan, polyethylene oxide (PEO) and Colocasia esculenta flour (CE flour) by using the electrospinning method. Two different nanofibers were formulated, containing chitosan-PEO and chitosan-PEO-CE flour. The higher concentration of PEO (3%chitosan-6%PEO) (w/v) resulted in more uniform chitosan-PEO electrospun nanofibers without beads. Chitosan-PEO-CE flour was prepared by addition of colloidal CE flour into the solution containing 3%chitosan-6%PEO with variation of the CE flour concentration of 5, 15 and 25% (w/v). Scanning Electron Microscopy demonstrated that the average diameter of chitosan-PEO nanofibers was 128±41 nm, whereas the diameter of chitosan-PEO-CE flour nanofibers was 159±45 …

Study On The Thermal Distortion, Hardness, And Microstructure Of St 37 Steel Plate Joined Using Fcaw, Maijuansyah Maijuansyah, Yanuar Rohmat Aji Pradana, Gaguk Jatisukamto, Solichin Solichin

Journal of Mechanical Engineering Science and Technology (JMEST)

This study sets out to investigate the distortion angle, microstructure, and hardness of St 37 steel plate weld joint produced by FCAW using the welding current of 80, 110, and 140 A. By using flat position, CO2 and E71T-1 wire were utilized as a shielding gas and electrode filler, respectively. The distortion angle measurement was done on 3 different locations of the welded sample perpendicular to weld direction by using bevel protractor. The micro Vickers tests were then applied gradually at the crosssectional surface with a distance of 0, 5, 10 and 15 mm from weld centerline using the load …

Comparison Study Of Mechanical Properties Of Al-Si Alloy With And Without Nanoreinforce Iron Oxide (Fe2o3), Cepi Yazirin, Poppy Puspitasari, Muhamad Fatikul Arif

Journal of Mechanical Engineering Science and Technology (JMEST)

Nanoreinforce materials such as ZnO, eggshell, Al2O3, TiO2, and ZrO2 have been shown to improve the mechanical properties of Al-Si alloy. Nanomaterial Fe2O3 has many applications as catalysts reaction in electronic devices, for example, semiconductor materials, paint formulations, lithium rechargeable batteries, and is often applied in industrial fields. It is known that Fe2O3 can be synthesized through the stirring process on machine and method used will involve several steps that relatively take a long time. In this study, Al-Si alloy reinforced by using nanomaterial Fe2O3 which sintered at a temperature of 600C for 3 hours aimed to improve mechanical and …

The Effect Of Chemical Pretreatment Process On Mechanical Properties And Porosity Of Bacterial Cellulose Film, Tito Arif Sutrisno, Heru Suryanto, Retno Wulandari, M. Muhajir, Shikh Mohd Shahrul Nizan Shikh Zahari

Journal of Mechanical Engineering Science and Technology (JMEST)

Bacterial cellulose (BC) is a natural polymer which have superior properties, like high porosity, high purity, and high permeability. The study objective is to determine the influence of chemical pretreatment on tensile strength and the porosity of BC. The method was to make BC films from pineapple peel extract through fermentation process for 14 days. The pretreatment was conducted by immersion of BC in BmimCl, H2O2, and NaOH solution with a concentration of 2.5%; 5%; and 7.5 %, heated at 80 °C then dried in the oven, and the samples were then tested by a tensile test using ASTM-D636-V standard, …