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News Article | May 24, 2017
Site: www.eurekalert.org

The research group led by Profs. FU Qiang and BAO Xinhe from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences revealed both the geometric constraint and confinement field in two-dimensional (2D) space between a graphene overlayer and Pt(111). The researchers demonstrated a new concept of confined catalysis under 2D materials, which they have named "catalysis under cover." These findings were published in the latest issue of PNAS, in an article entitled "Confined catalysis under two-dimensional materials." Small spaces in nanoreactors may have big implications for chemistry. The chemical nature of molecules and reactions within nanospaces can be changed significantly due to the nanoconfinement effect. Understanding the fundamentals of confined catalysis has become an important topic in heterogeneous catalysis. 2D nanoreactors formed under 2D materials can provide a well-defined model for exploring confined catalysis. The scientists chose a graphene/Pt (111) surface as a model for studying confined catalysis using density functional theory (DFT) calculations. They showed that the adsorption of atoms and molecules on the Pt(111) surface is weakened under graphene. A similar result has been found on Pt(110) and Pt(100) surfaces covered with graphene. Both the geometric constraint and confinement field imposed by the 2D cover are attributed to the observed confinement phenomena. The general tendency for weakened surface adsorption under the confinement of a graphene overlayer enables feasible modulation of surface reactions by placement of a 2D cover. The concept "catalysis under cover" can be applied to reactions between two opposite 2D walls interacting with each other through van der Waals forces. The concept helps in the design of high-performance nanocatalysts interfacing with 2D material overlayers. The research group demonstrated the confinement-induced modulation of surface reactivity in a Pt-catalyzed oxygen reduction reaction (ORR) under 2D covers. It is known that oxygen binding to Pt is relatively strong and all means of weakening this binding can be used to promote the reaction. When placing different 2D materials such as graphene and h-BN on the surface, oxygen binding with Pt weakens, thus effectively enhancing ORR activity. Confined catalysis under 2D materials can be applied to supported nanocatalysts. Metal nanoparticles may be encapsulated by 2D materials, thus forming core-shell nanostructures. The active core structures are well protected by the outer shells and catalyst stability is improved. Furthermore, catalyst activity can be enhanced by the confinement of the outer shells. This study was supported by the National Natural Science Foundation of China, the Ministry of Science and Technology of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, and the Collaborative Innovation Center of Chemistry for Energy Materials.


Converting CO2 from a detrimental greenhouse gas into value-added liquid fuels not only contributes to mitigating CO emissions, but also reduces dependence on petrochemicals. However, since CO is a fully oxidized, thermodynamically stable and chemically inert molecule, the activation of CO and its hydrogenation to hydrocarbons or other alcohols comprises challenging tasks. Most research to date, unsurprisingly, is focusing on selective hydrogenation of CO to short-chain products, while few studies on long-chain hydrocarbons, such as gasoline-range (C -C ) hydrocarbons. The key to this process is to search for a highly efficient catalyst. The research team led by Dr. SUN Jian and Prof. GE Qingjie in Dalian Institute of Chemical Physics has succeeded in preparing a highly efficient, stable, and multifunctional Na-Fe O /HZSM-5 catalyst for the direct production of gasoline from CO hydrogenation. This catalyst exhibited 78 percent selectivity to C -C as well as low CH4 and CO selectivity under industrial relevant conditions. And gasoline fractions are mainly isoparaffins and aromatics, thus favoring the octane number. Moreover, the multifunctional catalyst exhibited a remarkable stability for 1,000 h on stream, which definitely has the potential as a promising industrial catalyst for CO utilization to liquid fuels. In-depth characterizations indicate that this catalyst enables RWGS over Fe O sites, olefin synthesis over Fe C sites and oligomerization/aromatization/isomerization over zeolite acid sites. The concerted action of the active sites calls for precise control of their structures and proximity. This study paves a new path for the synthesis of liquid fuels by utilizing CO2 and H . Furthermore, it provides an important approach for dealing with the intermittency of renewable sources (sun, wind and so on) by storing energy in liquid fuels. This work was published in Nature Communications. More information: Jian Wei et al, Directly converting CO2 into a gasoline fuel, Nature Communications (2017). DOI: 10.1038/ncomms15174


News Article | October 26, 2016
Site: www.nature.com

Dalian National Laboratory will focus on reducing carbon emissions from coal. After five years of preparation, China has officially opened a clean-energy research centre that will spearhead the country's efforts to develop new ways to reduce its carbon emissions. "Our goal is to lead energy research in the country, and to rank among the world's top energy labs," says Can Li, head of the Dalian National Laboratory for Clean Energy (DNL), which was inaugurated in early October. Li says the facility will combine all major areas of energy research, including cleaner fossil fuels, solar power, and fuel cell technologies. The lab is based at the Dalian Institute of Chemical Physics (DICP), a subsidiary of the Chinese Academy of Sciences (CAS). The DNL's 600 scientists will be housed in a sprawling 40,000-square meter research complex on DICP's campus, where construction of the 204-million-renminbi (US$32 million) facility began in late 2006 after approval from the Chinese Ministry of Science and Technology. "Now is a major turning point for the DNL," says Tao Zhang, director of DICP. "We are transitioning from the planning and team-building stage to actual research." Mindful that China relies on coal for more than two-thirds of its electricity, Li expects the DNL to focus much of its resources on clean fossil-fuel technologies, at least initially. This plays to the strengths of the DICP, which has developed methanol-to-olefins conversion processes that help to reduce waste in the industrial processing of coal. In cooperation with the Shenhua Group, China's largest coal supplier, the DICP last year opened a factory using its technology. The DICP also has an ongoing energy research partnership with international oil giant BP. The DNL is expected to establish similar links with businesses and research institutions in China and abroad. "Much of the research scope is strategically defined by China's unique energy resources, and will be critical for the development of the country in the next few decades," says Peidong Yang, department head at the Joint Center for Artificial Photosynthesis at the Lawrence Berkeley National Laboratory in California. "Establishing the national lab is a great first step." The DNL's research into renewable energy sources will be more modest, however. "We are a latecomer in terms of solar-power research," says Li, who hopes that the lab will be able to leapfrog into more cutting-edge areas of renewable-energy research, such as artificial photosynthesis. The DNL sprang from the Chinese government's 2006 plan to set up ten national laboratories, each focusing on a broad topic, such as protein science or modern rail transportation. But the government has yet to set up a separate fund for those initiatives; the science ministry declined to comment on the situation. For now, the DICP is investing more than 289 million renminbi a year — over half of its annual research budget — in the DNL. More than half of that funding stream comes from DICP's business collaborations, with the remainder from government-funded research programs. "We are faced with some very fierce competition from labs all over the world, and money is one of the necessary ingredients to keep us going," says Li. "We hope for more funding from the government, but we are also prepared to generate revenues on our own."


« Quanergy acquires Otus People Tracker software from Raytheon BBN for advanced autonomous driving and security LiDAR applications | Main | NOHMs raises $5M for commercializing non-flammable, ionic-liquid containing electrolytes for EV batteries » Researchers at Dalian Institute of Chemical Physics (China) have synthesized an advanced catalytic layer in the membrane electroide assembly (MEA) for proton exchange membrane fuel cells (PEMFCs) using vertically aligned polymer–polypyrrole (PPy) nanowire arrays as ordered catalyst supports. In a paper published in the Journal of Power Sources, they report that a single cell fitted with their MEA yields a maximum performance of 762.1 mW cm−2 with a low Pt loading (0.241 mg Pt cm−2, anode + cathode). The advanced catalyst layer indicates better mass transfer in high current density than that of commercial Pt/C-based electrode. The mass activity is 1.08-fold greater than that of US Department of Energy (DOE) 2017 target. Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising alternative energy sources for stationary and transportation applications because of their high power density, quick start-up, zero or low emission, and low operating temperature. However, the cost of the PEMFCs must be reduced for wide adoption. Over the past decades, significant research has been devoted to decrease the cost of cell components without sacrificing their performance and durability and to decrease the amount of platinum (Pt). Many studies have focused on (1) the development of non-Pt-group metal catalysts and (2) the utilization of other metals (Pd, Fe, Co, Ni, and Cu) with Pt to form a core-shell structure or alloy, or the improvement of Pt utilization efficiency with an ordered electrode structure. Of these efforts, the development of advanced catalytic layer architecture is of importance to obtain an efficient membrane electrode assembly (MEA), which is the core part of PEMFCs and has significantly influenced the performance and durability of fuel cells. The team investigated PtPd alloy catalysts with various Pt loadings formed on PPy nanowire arrays in the anode or cathode (PtPd-PPy). The arrays were hot-pressed on both sides of a Nafion membrane to construct a membrane electrode assembly (without additional ionomer). The ordered thin catalyst layer (approximately 1.1 μm) was applied in a single cell as the anode and the cathode without additional Nafion ionomer. Since there is no additional ionomer on the catalyst layer of the proposed electrode, the water film acts as the proton-conducting pathway. They concluded that the high performance attained is due to the ordered electrode structure with a high Pt utilization and the improvement of the mass transport of the reactant and products in high current density. Broadly, the benefits of the approach are: However, cell performance needs further improvement through structure optimization. Our work provides a novel idea for the fabrication of a core-shell structure catalyst in the microscale and a new method to prepare a thin-film electrode. Furthermore, the approach developed in this work is of good scalability and is beneficial to the development of other fuel cells.


News Article | November 11, 2016
Site: www.cemag.us

Scientists from the Moscow Institute of Physics and Technology (MIPT), Semenov Institute of Chemical Physics of the Russian Academy of Sciences (ICP RAS), and Chuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine (ISC NASU) have proposed a model nanosized dipole photomotor based on the phenomenon of light-induced charge redistribution. Triggered by a laser pulse, this tiny device is capable of directed motion at a record speed and is powerful enough to carry a certain load. The research findings were published in the Journal of Chemical Physics. “The unprecedented characteristics of dipole photomotors based on semiconductor nanoclusters offer the prospect of more than just addressing a certain scarcity of the translational photomotors family. These devices could actually be applied wherever rapid nanoparticle transport is required. In chemistry and physics, they could help develop new analytical and synthetic instruments, while in biology and medicine they could be used to deliver drugs to diseased tissues, improve gene therapy strategies, and so on,” says Prof. Leonid Trakhtenberg of the Department of Molecular and Chemical Physics at MIPT, who is the leader of the research team and the head of the Laboratory of Functional Nanocomposites at ICP RAS. Prof. Trakhtenberg collaborated with Prof. Viktor Rozenbaum, who heads the Department of Theory of Nanostructured Systems at ISC NASU, to develop the theory of photoinduced molecular transport. This theory provides a framework for the design of nanomachines, whose motion can be controlled by a laser. The scientists have established the relationship between several model parameters (e.g., particle dimensions, photoexcitation conditions etc.) and the key performance characteristic of the device—its average velocity. Brownian Motors Directed nanomotors have prototypes in nature. Living organisms make use of protein devices driven by external nonequilibrium processes of a different nature, which are known as Brownian, or molecular motors. They are capable of converting random Brownian motion into directed translational motion, reciprocation, or rotation. Brownian motors are involved in muscle contraction, cell mobility (flagellar motility of bacteria), and the intra- and intercellular transport of organelles and relatively large particles of various substances (e.g., phagocytosis, or “cell eating”, and elimination of metabolic waste products from the cell). These devices operate with an amazingly high efficiency approaching 100%. “Understanding the underlying mechanisms of the operation of naturally occurring molecular motors enables us not only to replicate them but also to design new highly efficient multifunctional artificial devices that could eventually be applied in nanorobotics. For the last several decades, researchers and engineers in various fields have been working together and making some real progress towards the development of controllable nanomachines. The results of their work were recognized as a highly relevant achievement and a significant advance in science and technology, when the 2016 Nobel Prize in Chemistry was awarded ‘for the design and synthesis of molecular machines,’” says Prof.  Rozenbaum. A Brownian motor operates by switching between at least two discrete states, which is achieved by means of chemical reactions, thermal action, AC signals, or light pulses. In the latter case, the device is referred to as a photomotor. About ten years ago, a model was developed to describe the work of a translational dipole photomotor that operates due to photoexcitation of the molecule (particle) into a state with a dipole moment different from that in the ground state. The larger the difference between the total dipole moments of the nanoparticle in the two energy states, the higher the average velocity and efficiency of the motor. Laser Triggering The proposed motor is activated by a resonant laser pulse, which excites electrons in the cylinder-shaped semiconductor nanocluster causing a separation of charges and giving rise to an electrostatic interaction between the particle and the polar substrate. Subjecting the nanocylinder to periodic resonant laser pulses causes its potential energy in the field of the substrate to vary with time, which in turn enables directed motion. Photomotors based on inorganic nanoparticles outperform their organic molecule based counterparts in terms of efficiency and average velocity. In a cylinder-shaped semiconductor nanocluster, the value of the dipole moment before irradiation is close to zero, but photoexcitation of an electron from the bulk to the surface gives rise to an enormous dipole moment (approx. 40 D for a cylinder with a height of ca 15 Å). “Owing to the fact that the parameters of the device have been optimized, our proposed model photomotor based on a semiconductor nanocylinder moves at a record speed of 1 mm/s, which is approximately three orders of magnitude faster than similar models based on organic molecules or motor proteins in living organisms,” the authors of the study told us.


News Article | February 23, 2017
Site: www.eurekalert.org

The research group led by Profs. BAO Xinhe and YANG Fan from Dalian Institute of Chemical Physics of the Chinese Academy of Sciences discovered that oxide nanostructures (NSs) with a diameter below 3nm could exhibit an oxidation resistance much more superior than larger NSs. By investigating the oxidation mechanism at the atomic level, the team proposed, for the first time, a "dynamic size effect", that determines the stability of supported nanoparticles. These findings were published in the latest issue of Nature Communications, entitled "Enhanced oxidation resistance of active nanostructures via dynamic size effect". This study not only brings the atomic understanding of the dynamic remodeling mechanism of nanocatalyst under the atmosphere, but also provides a new interface control for the development of anti-corrosion and anti-oxidation nano-protective coating. A major challenge limiting the practical applications of nanomaterials is that the activities of NSs increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Yet, several nanocrystalline materials were also reported previously to exhibit improved oxidation resistance with respect to bulk materials and have been applied as anti-corrosion coatings. The lack of general consensus on the oxidation resistance of oxide NSs has been attributed to the limited understanding on the underlying mechanism of oxidation. Particularly, the oxidation kinetics of NSs with diameters below 5 nm have rarely been studied. Scientists thus constructed FeO NSs with different sizes on Pt (111) and studied their oxidation kinetics using high resolution scanning tunneling microscopy (STM) and density-functional theory (DFT) calculations. Reducing the size of active FeO NSs was found to increase drastically their oxidation resistance and a maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. The team found the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. Specifically, the study shows that FeO NSs with a size below 3.2 nm could undergo a facile and complete reconstruction, when O2 dissociates at the coordinatively unsaturated ferrous centers at the edges of FeO NSs. Accompanying the reconstruction, the dissociated oxygen atoms are stabilized at the edges of FeO NSs and could not penetrate into the interface FeO and Pt, thereby inhibiting the further oxidation of FeO NSs. FeO NSs with dimensions above 3.2 nm are easier to be oxidized, because of their inability to complete the reconstruction, accompanied by the formation of surface dislocations. In other words, small FeO NSs are more susceptible to dynamic changes in the reaction, to achieve a relatively stable structure. The authors term this as the "dynamic size effect" and found it to govern the chemical properties of active NSs. To demonstrate the generality of dynamic size effect, the researchers also studied CoO NSs supported on Pt (111) or Au (111), and found similar oxidation-resistant behavior for NSs below 3 nm.


News Article | February 24, 2017
Site: www.nanotech-now.com

Abstract: The research group led by Prof. BAO Xinhe from Dalian Institute of Chemical Physics, Chinese Academy of Sciences discovered that oxide nanostructures (NSs) with a diameter below 3 nm could exhibit an oxidation resistance much more superior than larger NSs. By investigating the oxidation mechanism at the atomic level, the team proposed, for the first time, a "dynamic size effect", that determines the stability of supported nanoparticles. These findings were published in the latest issue of Nature Communications, entitled "Enhanced oxidation resistance of active nanostructures via dynamic size effect". This study not only brings the atomic understanding of the dynamic remodeling mechanism of nanocatalyst under the atmosphere, but also provides a new interface control for the development of anti-corrosion and anti-oxidation nano-protective coating. A major challenge limiting the practical applications of nanomaterials is that the activities of NSs increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Yet, several nanocrystalline materials were also reported previously to exhibit improved oxidation resistance with respect to bulk materials and have been applied as anti-corrosion coatings. The lack of general consensus on the oxidation resistance of oxide NSs has been attributed to the limited understanding on the underlying mechanism of oxidation. Particularly, the oxidation kinetics of NSs with diameters below 5 nm have rarely been studied. BAO's team and Prof. YANG Fan thus constructed FeO NSs with different sizes on Pt (111) and studied their oxidation kinetics using high resolution scanning tunneling microscopy (STM) and density-functional theory (DFT) calculations. Reducing the size of active FeO NSs was found to increase drastically their oxidation resistance and a maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. The team found the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. Specifically, the study shows that FeO NSs with a size below 3.2 nm could undergo a facile and complete reconstruction, when O2 dissociates at the coordinatively unsaturated ferrous centers at the edges of FeO NSs. Accompanying the reconstruction, the dissociated oxygen atoms are stabilized at the edges of FeO NSs and could not penetrate into the interface FeO and Pt, thereby inhibiting the further oxidation of FeO NSs. FeO NSs with dimensions above 3.2 nm are easier to be oxidized, because of their inability to complete the reconstruction, accompanied by the formation of surface dislocations. In other words, small FeO NSs are more susceptible to dynamic changes in the reaction, to achieve a relatively stable structure. The authors term this as the "dynamic size effect" and found it to govern the chemical properties of active NSs. To demonstrate the generality of dynamic size effect, the researchers also studied CoO NSs supported on Pt (111) or Au (111), and found similar oxidation-resistant behavior for NSs below 3 nm. 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.


News Article | February 16, 2017
Site: www.newscientist.com

The chemistry that gives festive sparklers their sparkle could be used to reduce the hazards of falling space junk. Researchers have demonstrated that a mixture similar to that used in fireworks can help bring dead satellites back to Earth safely. Descending space junk largely ends up in the oceans, but that doesn’t mean we can turn a blind eye to the issue. In 2011, a Delta II rocket stage and a fuel tank came to Earth in Mongolia. Last year an old Chinese rocket stage landed in Myanmar, shaking houses. “We actually get quite a lot of stuff falling,” said William Ailor at Aerospace, a non-profit company in California that studies orbital debris. Safely de-orbiting dead satellites or used rocket stages is a serious challenge, and space agencies around the world are working on solutions. Part of the problem is that a lot of space junk is made of titanium, which has a high melting point: about 1670 °C. Most satellites completely burn up in our atmosphere, but the titanium alloy pieces are more likely to survive re-entry. Even worse, some of these are aerodynamically shaped, making them more likely to reach the ground. Now, Denis Dilhan at the French space agency and his colleagues have come up with a solution: making metal satellite parts burn up more efficiently as they enter the atmosphere, using thermite – a mixture of metal powder, fuel and metal oxide. Best known for its role in fireworks and welding, it releases heat when ignited. The team say bits of thermite attached to titanium components would self-ignite when a satellite (or a piece of it) hits the upper atmosphere. That could melt holes in the metal, changing the shape of components and making them more likely to break up. A team led by Konstantin Monogarov at the Semenov Institute of Chemical Physics in Moscow, Russia, came up with a working thermite formula that would suit this application. To do this, they strapped various types of thermite to some titanium and fired a laser at it. A mixture of aluminium and cobalt oxide worked best: it took less time to ignite than other formulations, and did so at a lower temperature – down to about 590 °C if the aluminium particles are nano-sized. It’s a clever idea, says Ailor. If future satellites included thermite, they would need less fuel because there would be no need for a de-orbit burn to put them on what seems a safe trajectory. Apart from there being much less chance of a spent rocket tank or stage ending up in a farmer’s field, use of thermite would save money and effort, too. But in the real world, a thermite pellet might get shielded from re-entry heat – it might be on the trailing side of the spacecraft, for example – and so have trouble igniting. “The issue is verification,” says Ailor. “How do you know it’s doing what you thought it would?”


Reactions occurring at a carbon atom with a tetrahedral environment proceeding through the back-side attack Walden inversion mechanism are one of the most important and useful classes of reactions in chemistry. The bimolecular nucleophilic substitution (SN2) reaction is the most common reaction of that type. In a SN2 reaction, a nucleophile approaches a saturated carbon from one side, displaces a leaving group on the opposite side of the carbon atom, resulting in inversion of the carbon center. Decades of extensive studies revealed that a gas-phase SN2 reaction with a center barrier exhibits an inverse secondary kinetic isotope effect (KIE) on thermal rate constant at room temperature, i.e. kH/kD A research term led by Prof. ZHANG Donghui from State Key Laboratory of Molecular Reaction Dynamics of Dalian Institute of Chemical Physics has carried out an accurate quantum dynamics study of the H' + CH4 � CH3H' + H substitution reaction and its isotope analogies. The reaction is the simplest reaction proceeding through the back-side attack Walden inversion mechanism, with a D3h transition state and a static barrier height of 1.6 eV. It is very similar to the gas-phase SN2 reactions with central barriers, except that there exists pre- and post-reaction wells in SN2 reactions stemming from strong ion-dipole interaction between reagents/products. They found that the reaction threshold energy is considerably higher than the barrier height, and the reaction manifests different isotope effect. In term of cross section beyond reaction threshold energy, it has a large normal secondary isotope effect with the reactivity for the H' + CH4 � CH3H' + H reaction substantially larger than that for H' + CHD3 � CD3H' + H reaction. However, in term of thermal rate constant it has a reverse secondary KIE with the rate for H + CH4 slightly smaller than that for H + CHD3. In order to explore the dynamics origin of these different isotope effects, they analyzed the change of the umbrella angle of the non-reacting methyl group as the reaction proceeds. According to the minimum energy path (MEP), the umbrella angle should change synchronously during the reaction with the incoming of H atom and elongation of the breaking CH bond to reach 90° at the static saddle point. However, it turned out that for the H' + CHD3 substitution reaction the umbrella motion of the non-reacting CD3 group is slow in responding to the attack of the incoming H atom during the reaction. The reaction does not proceed along MEP as shown by the black reaction path in the figure. Instead, it proceeds on the red path with the umbrella angle larger than 90° at the dynamical saddle point and the corresponding barrier height higher than the static barrier height. Because the umbrella motion depends on the masses of the methyl group, isotope replacement of D atom to H atom can enhance the reactivity substantially, resulting in a large normal isotope effect on cross sections. Furthermore, because the initial umbrella excitation of methyl group can accelerate the umbrella motion during reaction substantially, it can dramatically enhance the reactivity. As a result, the thermal rate constant for the reaction is exclusively determined by the contributions from the umbrella excited states. As the contributions from the umbrella excited states for the H + CD3H reaction beat those for the H + CH4 reaction, the reaction exhibits an inverse secondary KIE. All the phenomena found from this study for the H+CH4 substitution reactions, including higher threshold energy, a reverse secondary KIE at room temperature, and a large normal isotope effect for reaction cross section, have been observed for gas-phase SN2 reactions with barriers. We anticipate that the mechanisms uncovered from this study play important roles in these gas-phase SN2 reactions. Therefore, this study only not represents the first accurate theoretical study of a Walden inversion reaction which provided unprecedented dynamical details and a clear physical picture of the dynamics, but also sheds light on the dynamics of gas-phase SN2 reactions.


News Article | November 3, 2016
Site: www.rdmag.com

Scientists from the Semenov Institute of Chemical Physics of the Russian Academy of Sciences (ICP RAS) and the Moscow Institute of Physics and Technology (MIPT) have demonstrated that sensors based on binary metal oxide nanocomposites are sensitive enough to identify terrorist threats and detect environmental pollutants. The results of their study have been published in Sensors and Actuators B: Chemical. Due to rapid industrial growth and the degradation of the environment, there is a growing need for the development of highly effective and selective sensors for pollutant detection. In addition, gas sensors could also be used to monitor potential terrorist threats. "Choosing the right sensor composition can make a device at least ten times more effective and enable an exceptionally fast response, which is crucial for preventing terrorist attacks," says Prof. Leonid Trakhtenberg of the Department of Molecular and Chemical Physics at MIPT, who is the leader of the research team and the head of the Laboratory of Functional Nanocomposites at ICP RAS. According to the research findings, the most promising detection systems are binary metal oxide sensors, in which one component provides a high density of conductive electrons and another is a strong catalyst. A mixed system of that kind has the two necessary components for effective gas detection, viz., an electron donor and a substance "accommodating" the reaction. An additional factor contributing to faster sensor response is the formation of chemisorption centers, i.e., the chemically active spots on the nanocrystals that facilitate gas molecule adsorption. "We are planning further research into the possibilities for sensor design presented by the multicomponent metal oxide nanocomposites incorporating nanofibers. The development of new effective sensor compositions will be based on a reasonably balanced approach involving both the experimental tests and the advancement of our theoretical understanding of the sensing mechanisms," comments Prof. Trakhtenberg. A rather promising approach to the development of new gas detection systems is the use of "core-shell type" composite metal oxide nanofibers, where the "core" and the "shell" are composed of two different oxides.

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