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News Article | April 28, 2016
Site: www.materialstoday.com

The secret to making the best energy storage materials is growing them with as much surface area as possible. This requires just the right mixture of ingredients prepared in a specific amount and order at just the right temperature to produce a thin sheet of material with the perfect chemical consistency to store energy. A team of researchers from Drexel University, and Huazhong University of Science and Technology (HUST) and Tsinghua University in China, recently discovered a way to improve the recipe and make the resulting materials both bigger and better at soaking up energy. The secret? Just add salt. The team's findings, which are published in a paper in Nature Communications, show that using salt crystals as a template to grow thin sheets of conductive metal oxides produces materials that are larger and possess a greater chemical purity, making them better suited for gathering ions and storing energy. "The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, a professor at HUST's Wuhan National Laboratory for Optoelectronics and an author of the paper. "Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated." In an energy storage device – a battery or a capacitor, for example – energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve, they're becoming smaller and capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and disbursing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to bind to them – which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to the researchers, the problem lies in the process of making the metal oxide nanosheets, which involves either deposition from a gas or chemical etching. Both these processes often leave trace chemical residues that contaminate the material and prevent ions from bonding to it. In addition, materials made in this way are often just a few square micrometers in size. Using salt crystals as a substrate for growing the metal oxide crystals lets them spread out and form a larger sheet of oxide material. Analogous to making a waffle by dripping batter into a pan versus pouring it into a big waffle iron, the key to getting a big, sturdy product is getting the solution – be it batter or a chemical compound – to spread evenly over the template and stabilize in a uniform way. "This method of synthesis, called 'templating' – where we use a sacrificial material as a substrate for growing a crystal – is used to create a certain shape or structure," explained Yury Gogotsi, a professor in Drexel's College of Engineering and head of the A.J. Drexel Nanomaterials Institute, who was another author of the paper. "The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thin, strong and stable nanocrystal. This is the key finding of our research – it means that different salts must be used to produce different oxides." Researchers have used a variety of chemicals, compounds, polymers and objects as growth templates for nanomaterials, but this discovery shows the importance of matching a template to the structure of the material being grown. Salt crystals turn out to be the perfect substrate for growing oxide sheets of magnesium, molybdenum and tungsten. The precursor solution coats the sides of the salt crystals as the oxides begin to form. After they've solidified, the salt is dissolved in a wash, leaving nanometer-thin two-dimensional (2D) sheets on the sides of the salt crystals – and little trace of any contaminants that might hinder their energy storage performance. By making oxide nanosheets in this way, the only factors that limit their growth are the size of the salt crystals and the amount of precursor solution used. "Lateral growth of the 2D oxides was guided by salt crystal geometry and promoted by lattice matching and the thickness was restrained by the raw material supply. The dimensions of the salt crystals are tens of micrometers and guide the growth of the 2D oxide to a similar size," the researchers write in the paper. "On the basis of the naturally non-layered crystal structures of these oxides, the suitability of salt-assisted templating as a general method for synthesis of 2D oxides has been convincingly demonstrated." As predicted, the larger size of the oxide sheets equated to a greater ability to collect and disburse ions from an electrolyte solution – the ultimate test for energy storage devices. Results reported in the paper suggest that use of these materials may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. Gogotsi, along with his students in Drexel’s Department of Materials Science and Engineering, has been collaborating with HUST since 2012 to explore a wide variety of materials for energy storage applications. The lead author of the Nature Communications paper, Xu Xiao, and co-author Tiangi Li, both Zhou's doctoral students, came to Drexel as exchange students to learn about its supercapacitor research. Those visits started a collaboration that was supported by Gogotsi's annual trips to HUST. While the partnership has already yielded five joint publications, Gogotsi speculates that this work is just beginning. "The most significant result of this work thus far is that we've demonstrated the ability to generate high-quality 2D oxides with various compositions," Gogotsi said. "I can certainly see expanding this approach to other oxides that may offer attractive properties for electrical energy storage, water desalination membranes, photocatalysis and other applications." This story is adapted from material from Drexel University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.


Home > Press > Adding some salt to the recipe for energy storage materials: Researchers use common table salt as growth template Abstract: The secret to making the best energy storage materials is growing them with as much surface area as possible. Like baking, it requires just the right mixture of ingredients prepared in a specific amount and order at just the right temperature to produce a thin sheet of material with the perfect chemical consistency to be useful for storing energy. A team of researchers from Drexel University, Huazhong University of Science and Technology (HUST) and Tsinghua University recently discovered a way to improve the recipe and make the resulting materials bigger and better and soaking up energy -- the secret? Just add salt. The team's findings, which were recently published in the journal Nature Communications, show that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure -- which makes them better suited for gathering ions and storing energy. "The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, a professor at HUST's Wuhan National Laboratory for Optoelectronics and an author of the research. Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated." In an energy storage device -- a battery or a capacitor, for example -- energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve they're becoming smaller and capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and disbursing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to attach -- which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to Zhou, Tang and the team from HUST, the problem lies in the process of making the nanosheets -- which involves either a deposition from gas or a chemical etching -- often leaves trace chemical residues that contaminate the material and prevent ions from bonding to it. In addition, the materials made in this way are often just a few square micrometers in size. Using salt crystals as a substrate for growing the crystals lets them spread out and form a larger sheet of oxide material. Think of it like making a waffle by dripping batter into a pan versus pouring it into a big waffle iron; the key to getting a big, sturdy product is getting the solution -- be it batter, or chemical compound -- to spread evenly over the template and stabilize in a uniform way. "This method of synthesis, called 'templating' -- where we use a sacrificial material as a substrate for growing a crystal -- is used to create a certain shape or structure," said Yury Gogotsi, PhD, University and Trustee Chair professor in Drexel's College of Engineering and head of the A.J. Drexel Nanomaterials Institute, who was an author of the paper. "The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thing, strong and stable nanocrystal. This is the key finding of our research -- it means that different salts must be used to produce different oxides." Researchers have used a variety of chemicals, compounds, polymers and objects as growth templates for nanomaterials. But this discovery shows the importance of matching a template to the structure of the material being grown. Salt crystals turn out to be the perfect substrate for growing oxide sheets of magnesium, molybdenum and tungsten. The precursor solution coats the sides of the salt crystals as the oxides begin to form. After they've solidified, the salt is dissolved in a wash, leaving nanometer-thin two-dimensional sheets that formed on the sides of the salt crystal -- and little trace of any contaminants that might hinder their energy storage performance. By making oxide nanosheets in this way, the only factors that limit their growth is the size of the salt crystal and the amount of precursor solution used. "Lateral growth of the 2D oxides was guided by salt crystal geometry and promoted by lattice matching and the thickness was restrained by the raw material supply. The dimensions of the salt crystals are tens of micrometers and guide the growth of the 2D oxide to a similar size," the researchers write in the paper. "On the basis of the naturally non-layered crystal structures of these oxides, the suitability of salt-assisted templating as a general method for synthesis of 2D oxides has been convincingly demonstrated." As predicted, the larger size of the oxide sheets also equated to a greater ability to collect and disburse ions from an electrolyte solution -- the ultimate test for its potential to be used in energy storage devices. Results reported in the paper suggest that use of these materials may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. Gogotsi, along with his students in the Department of Materials Science and Engineering, has been collaborating with Huazhong University of Science and Technology since 2012 to explore a wide variety of materials for energy storage application. The lead author of the Nature Communications article, Xu Xiao, and co-author Tiangi Li, both Zhou's doctoral students, came to Drexel as exchange students to learn about the University's supercapacitor research. Those visits started a collaboration, which was supported by Gogotsi's annual trips to HUST. While the partnership has already yielded five joint publications, Gogotsi speculates that this work is only beginning. "The most significant result of this work thus far is that we've demonstrated the ability to generate high-quality 2D oxides with various compositions," Gogotsi said. "I can certainly see expanding this approach to other oxides that may offer attractive properties for electrical energy storage, water desalination membranes, photocatalysis and other applications." For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Gao H.,Northwestern University | Hu J.,HUST | Wilson C.,U. C. Santa Barbara | Li Z.,Northwestern University | And 2 more authors.
Proceedings of the ACM Conference on Computer and Communications Security | Year: 2010

Online social networks (OSNs) are exceptionally useful collaboration and communication tools for millions of users and their friends. Unfortunately, in the wrong hands, they are also extremely effective tools for executing spam campaigns and spreading malware. In this poster, we present an initial study to detect and quantitatively analyze the coordinated spam campaigns on online social networks in the wild. Our system detected about 200K malicious wall posts with embedded URLs, traced back to roughly 57K accounts. We find that more than 70% of all malicious wall posts are advertising phishing sites.


Xiao F.,HUST | Zhang Z.,HUST | Yin X.,HUST
Proceedings of the Universities Power Engineering Conference | Year: 2015

There are many forms of network structures in the process of smart substation layer. It is significant to research the process layer's reliability under different network structures of relay protection system for the network structure selection of process layer and engineering application. Based on the digitized substation relay protection system structure characteristic, this paper puts forward a reliability analysis method for protection system. The protection system is divided into sampling subsystem and trip subsystem and their fault tree models are established respectively. The method comprehensively considers the equipment failure and repair process and makes use of the fault tree and Monte Carlo simulation to solve the reliability of protection system. Finally, the proposed method is used to evaluate the reliability of the protection system with different network structures. The main elements affecting the reliability of protection system are given by the analysis of the component probability importance. © 2015 IEEE.


Lu L.,Huazhong University of Science and Technology | Shi B.-C.,HUST
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Walsh-Haar function system that was first introduced by us is a new kind of function systems, and has a good global / local property. This function system is called Walsh ordering function system since its generation kernel functions belong to Walsh ordering Walsh function system. We worked out a recursive property of the matrix WH KR m+1 corresponding to the first KR m+1 Walsh-Haar functions in Walsh-Haar function system, and proved that Walsh-Haar function system is perfect and orthogonal similar to Walsh function system and Haar function system. Thus, discrete Walsh-Haar transformation (DW-HT) is an orthogonal transformation that can be widely used in signal processing. In this paper, using the recursive property of the matrix WH KR m+1 and the fast algorithm of discrete Walsh transformation in Walsh ordering, we have designed a fast algorithm of Walsh ordering (k, k-1) type DW-HT based on the bisection technique. As one of its applications, we use it to detect image edges. Compare with some edge-detecting methods, the method in this paper detects more details of image edge. The idea and method used to design the fast algorithm in this paper can be used to design fast algorithms of other ordering (k, k-1) type DW-HTs and other discrete orthogonal transformations. © 2011 SPIE.


Zhang H.-M.,Dr An Yuan Guos Group | Kuang S.,Dr An Yuan Guos Group | Xiong X.,HUST | Gao T.,HUST | And 2 more authors.
Briefings in Bioinformatics | Year: 2013

Transcription factors (TFs) and microRNAs (miRNAs) can jointly regulate target gene expression in the forms of feed-forward loops (FFLs) or feedback loops (FBLs).These regulatory loops serve as important motifs in gene regulatory networks and play critical roles in multiple biological processes and different diseases. Major progress has been made in bioinformatics and experimental study for theTF andmiRNA co-regulation in recent years. To further speed up its identification and functional study, it is indispensable to make a comprehensive review. In this article, we summarize the types of FFLs and FBLs and their identifiedmethods. Then, we review the behaviors and functions for the experimentally identified loops according to biological processes and diseases. Future improvements and challenges are also discussed, which includesmore powerful bioinformatics approaches and high-throughput technologies inTF and miRNA target prediction, and the integration of networks of multiple levels. © The Author 2013. Published by Oxford University Press.


BinMerdhah A.B.,HUST | Yassin A.A.M.,FKKKSA | Muherei M.A.,HUST
Journal of Petroleum Science and Engineering | Year: 2010

Scale formation in surface and subsurface oil and gas production equipment has been recognized to be a major operational problem. It has been also recognized as major causes of formation damage either in injection or producing wells. This study was conducted to investigate the permeability reduction caused by deposition of barium sulfate in sandstone cores from mixing of injected seawater and formation water that contained high concentration of barium ion at various temperatures (50-80 °C) and differential pressures (100-200 psig). The solubility of barium sulfate scale formed and how its solubility was affected by changes in salinity and temperatures (40-90 °C) were also studied. The morphology and particle size of scaling crystals formed as shown by Scanning Electron Microscopy (SEM) were also presented. The results showed that a large extent of permeability damage was caused by barium sulfate that deposited on the rock pore surface. The rock permeability decline indicates the influence of the concentration of barium ions. At higher temperatures, the deposition of BaSO4 scale decreases since the solubility of BaSO4 scale increases with increasing temperature. The deposition of BaSO4 scale during flow of injection waters into porous media was shown by Scanning Electron Microscopy (SEM) micrographs. The results were utilized to build a general reaction rate equation to predict BaSO4 deposition in sandstone cores for a given temperature, brine super-saturation and differential pressures. © 2009 Elsevier B.V. All rights reserved.


Haikou, one of leading historical and cultural city, whose history block and the building overhang is paid close attention to, because of whose entire and continuous value. But it is a long time since established, the function layout and the appearance elements are old, which is far away from the need of society, economy and culture development nowadays, is badly in need of reform. With the start of example area in history cultural block and the following survey, author is going to do a further study of reforming old city background, seeking out suitable local planning method and principle. The article expounds the background, target and constructs intention of Haikou historical block planning design, providing the extended train of thought about the historical block renewal. © (2011) Trans Tech Publications.


Lee M.-H.,National Yunlin University of Science and Technology | Lee M.-H.,Hsiuping University of Science and Technology | Chen J.-R.,Hsiuping University of Science and Technology | Shiue G.-Y.,HUST | And 2 more authors.
Journal of the Taiwan Institute of Chemical Engineers | Year: 2014

To explore the thermal runaway behavior of benzoyl peroxide (BPO) in industrial processes during upsets situations and to compare the difference of values between simulation and experimentation, two calorimeters, differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), were employed to measure thermokinetic data of the thermal decomposition of BPO, and to calculate values of parameters by simulation approach, which were based on kinetic models and the thermal safety software. This study shows the novel finding that benzoyl peroxide (BPO) has an autocatalytic reaction at low temperature. The simulation results showed that the Ea value was 124kJ/mol by VSP2 tests. The Ea value was much closer to Zaman's studies than the Ea values developed by the Kissinger and/or Ozawa methods. The Ea value resulting from the optimal fit approach average was 91.47±17.69kJ/mol also closer to Zaman's studies than values from the Kissinger and Ozawa methods. © 2013 Taiwan Institute of Chemical Engineers.


The team's findings, which were recently published in the journal Nature Communications, show that using salt crystals as a template to grow thin sheets of conductive metal oxides make the materials turn out larger and more chemically pure—which makes them better suited for gathering ions and storing energy. "The challenge of producing a metal oxide that reaches theoretical performance values is that the methods for making it inherently limit its size and often foul its chemical purity, which makes it fall short of predicted energy storage performance," said Jun Zhou, a professor at HUST's Wuhan National Laboratory for Optoelectronics and an author of the research. Our research reveals a way to grow stable oxide sheets with less fouling that are on the order of several hundreds of times larger than the ones that are currently being fabricated." In an energy storage device—a battery or a capacitor, for example—energy is contained in the chemical transfer of ions from an electrolyte solution to thin layers of conductive materials. As these devices evolve they're becoming smaller and capable of holding an electric charge for longer periods of time without needing a recharge. The reason for their improvement is that researchers are fabricating materials that are better equipped, structurally and chemically, for collecting and disbursing ions. In theory, the best materials for the job should be thin sheets of metal oxides, because their chemical structure and high surface area makes it easy for ions to attach—which is how energy storage occurs. But the metal oxide sheets that have been fabricated in labs thus far have fallen well short of their theoretical capabilities. According to Zhou, Tang and the team from HUST, the problem lies in the process of making the nanosheets—which involves either a deposition from gas or a chemical etching—often leaves trace chemical residues that contaminate the material and prevent ions from bonding to it. In addition, the materials made in this way are often just a few square micrometers in size. Using salt crystals as a substrate for growing the crystals lets them spread out and form a larger sheet of oxide material. Think of it like making a waffle by dripping batter into a pan versus pouring it into a big waffle iron; the key to getting a big, sturdy product is getting the solution—be it batter, or chemical compound—to spread evenly over the template and stabilize in a uniform way. "This method of synthesis, called 'templating'—where we use a sacrificial material as a substrate for growing a crystal—is used to create a certain shape or structure," said Yury Gogotsi, PhD, University and Trustee Chair professor in Drexel's College of Engineering and head of the A.J. Drexel Nanomaterials Institute, who was an author of the paper. "The trick in this work is that the crystal structure of salt must match the crystal structure of the oxide, otherwise it will form an amorphous film of oxide rather than a thing, strong and stable nanocrystal. This is the key finding of our research—it means that different salts must be used to produce different oxides." Researchers have used a variety of chemicals, compounds, polymers and objects as growth templates for nanomaterials. But this discovery shows the importance of matching a template to the structure of the material being grown. Salt crystals turn out to be the perfect substrate for growing oxide sheets of magnesium, molybdenum and tungsten. The precursor solution coats the sides of the salt crystals as the oxides begin to form. After they've solidified, the salt is dissolved in a wash, leaving nanometer-thin two-dimensional sheets that formed on the sides of the salt crystal—and little trace of any contaminants that might hinder their energy storage performance. By making oxide nanosheets in this way, the only factors that limit their growth is the size of the salt crystal and the amount of precursor solution used. "Lateral growth of the 2D oxides was guided by salt crystal geometry and promoted by lattice matching and the thickness was restrained by the raw material supply. The dimensions of the salt crystals are tens of micrometers and guide the growth of the 2D oxide to a similar size," the researchers write in the paper. "On the basis of the naturally non-layered crystal structures of these oxides, the suitability of salt-assisted templating as a general method for synthesis of 2D oxides has been convincingly demonstrated." As predicted, the larger size of the oxide sheets also equated to a greater ability to collect and disburse ions from an electrolyte solution—the ultimate test for its potential to be used in energy storage devices. Results reported in the paper suggest that use of these materials may help in creating an aluminum-ion battery that could store more charge than the best lithium-ion batteries found in laptops and mobile devices today. Gogotsi, along with his students in the Department of Materials Science and Engineering, has been collaborating with Huazhong University of Science and Technology since 2012 to explore a wide variety of materials for energy storage application. The lead author of the Nature Communications article, Xu Xiao, and co-author Tiangi Li, both Zhou's doctoral students, came to Drexel as exchange students to learn about the University's supercapacitor research. Those visits started a collaboration, which was supported by Gogotsi's annual trips to HUST. While the partnership has already yielded five joint publications, Gogotsi speculates that this work is only beginning. "The most significant result of this work thus far is that we've demonstrated the ability to generate high-quality 2D oxides with various compositions," Gogotsi said. "I can certainly see expanding this approach to other oxides that may offer attractive properties for electrical energy storage, water desalination membranes, photocatalysis and other applications." Explore further: New nanosheet growth technique has potential to revolutionize nanotechnology industry

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