Сколтех — новый технологический университет, созданный в 2011 году в Москве командой российских и зарубежных профессоров с мировым именем. Здесь преподают действующие ученые, студентам дана свобода в выборе дисциплин, обучение включает работу над собственным исследовательским проектом, стажировку в индустрии, предпринимательскую подготовку и постоянное нахождение в международной среде.

Архив метки: nanometer

Seminar: Nanomaterials For Industrial Applications: Theory Contributions To Heterogeneous Catalysis, Gas Separation And Storage

Nanomaterials are increasingly used by various industries. Image courtesy of Brookhaven National Laboratory

Nanomaterials are increasingly used by various industries. Image courtesy of Brookhaven National Laboratory

How can researchers support industry by designing new nanometer-sized materials with outstanding features?

Join us as we host Dr. Andreas Hauser for a seminar titled “Nanomaterials For Industrial Applications: Theory Contributions To Heterogeneous Catalysis, Gas Separation And Storage”

When: November 20, 2014; 13.30 – 15.00

Where: Russian Quantum Center Auditorium, Ural building (-1 floor), Moscow School of Management

SEMINAR ABSTRACT

The properties of molecular structures in the nanometer range and below vary significantly with system size. Though difficult to predict and far from the asymptotic bulk properties, these fluctuations leave a lot of freedom for the design of novel materials with outstanding features.

This talk focuses on the application of electronic structure theory to a selection of topical problems such as membranes for chiral resolution of drug molecules or the separation and storage of gases, and the usage of subnanometer-sized metal particles for heterogeneous catalysis.

Special focus is given to bimetallic alloys for the dehydrogenation of “light end alkanes”, which could open a potential pathway to efficient alkane metathesis and oligomerization reactions.

Their relevance in the context of renewable energies as well as petroleum industries is discussed. Potential projects and their embedding into teaching concepts are suggested to stimulate an open discussion.

Dr. Andreas Hauser, guest speaker at the Skoltech seminar

Dr. Andreas Hauser, guest speaker at the Skoltech seminar

SPEAKER INTRODUCTION

Dr. Andreas Hauser is a physicist working in the field of theoretical chemistry and was recently employed at UC Berkeley as a joint postdoc in the groups of Prof. Martin Head-Gordon (Theoretical Chemistry) and Prof. Alex T. Bell (Biomolecular and Chemical Engineering).

During his stay he participated in the XC2 initiative, a research project of British Petrol on Light Ends Upgrading, Fischer-Tropsch Synthesis, Biomass Deoxygenation and Oxygenate Coupling.

Previous postdoctoral research in the group of Prof. Peter Schwerdtfeger was concerned with the application of nanoporous membranes to various problems of gas separation and storage.

The Perfect Defect: Researcher Unveils Nanowire Growth Mystery

Growing nanowires is a delicate and complex process. Now a Skoltech researcher teamed up with international scientists to reveal a new way to monitor and guide growth by using the material's defects. Image courtesy of nist.gov

Growing nanowires is a delicate and complex process. Now a Skoltech researcher teamed up with international scientists to reveal a new way to monitor and guide growth by using the material’s defects. Image courtesy of nist.gov

Nano-wires have fascinated and intrigued researchers for decades. These extremely thin and elongated structures (10−9 meter) are considered to be promising materials for high efficiency electronic devices. They are particularly useful in chemical and biological sensors, solar cells, field emission devices, and lasers. But crucial parts of the process that guide their growth remained a mystery. Now Professor Albert Nasibulin, a researcher at Skoltech, teamed up with colleagues from Denmark and Finland to reveal new facts about the behavior of nano-wires during metal oxidation: the process occurs without catalysts and is guided by planar defects. Simply put, faults serve as both guides and engines for growth. The researchers published their findings in the scientific journal Nano Letters. These could help future efforts to control the properties of nano-wires.

High yield nano-wires have applications in batteries and transparent conductive electrodes. Their use as tribological (interacting surfaces) additives is also high on many scientists priority list. Despite a wide scientific interest, nano-wires synthesis is usually limited to just a few methods in which a catalyst, namely gold nano-particles, plays the main role. In contrast, non-catalytic methods produce purer nano-materials and could minimize the number of technological steps required for their production.

However, the process underlying nano-wire growth without a catalyst remained unknown. Moreover, it was widely disputed if any nano-scale wire growth is possible without using nanometer sized particles as guides.

Scanning electron microscopy images of various nanowires synthesized by heating metal at ambient conditions. Source Nanotechnology 20, 165603 (2009).

Scanning electron microscopy images of various nanowires synthesized by heating metal at ambient conditions. Source Nanotechnology 20, 165603 (2009).

In the past, researchers from Aalto University (Finland) proposed a novel method to grow metal oxide nano-wires without a catalyst, by simply oxidizing pure metals in air (Figure 1). However, the mechanism guiding their formation was not fully understood. Latest advances in electron microscopy allow for closer examination of chemical reactions without disrupting them.

Yet recently Prof. Albert Nasibulin of Skoltech (Skolkovo Institute of Science and Technology), Dr. Simas Rackauskas of Aalto University (Finland), and researchers from Kemerovo State University and the Technical University of Denmark have achieved a breakthrough: they examined in situ nano-wire growth.

The researchers synthesized CuO (Copper Oxide) nano-wires by oxidizing samples of pure copper inside a transmission electron microscope. Then they have been able to observe and follow the complete process of nano-wire formation. The atomic level investigation shows how layers of Copper Oxide are organized at the tip of growing nano-wire. They nucleate only at the specific position on the surface, which is associated with planar crystal defects known as twin boundaries.

Thus, the study unambiguously showed that nano-wire growth might occur without catalyst particles. Moreover, these observations reveal that all nanowires contain defects, which are crucial to guide the materials’ growth.

The nanowire growth starts from the atomic layer nucleation at the crystal defect (twin boundary) and continues forming a long range ordering along the defect. The figures show TEM images revealing the twin boundary defects in the nanowire crystal and the mechanism of its layer-by-layer growth (Source: Nano Letters. Article ASAP DOI: 10.1021/nl502687s).

The nanowire growth starts from the atomic layer nucleation at the crystal defect (twin boundary) and continues forming a long range ordering along the defect. The figures show TEM images revealing the twin boundary defects in the nanowire crystal and the mechanism of its layer-by-layer growth (Source: Nano Letters. Article ASAP DOI: 10.1021/nl502687s).

In the future, one can expect this work to be the starting point of a new approach. Defects could be used for nano-wire growth control. Consequently, they can even help shape the materials’ geometry, in a similar way to the catalyst assisted method (Figure 2).

“Catalyst-free methods are attractive for facile fabrication of pure nano-wires without the need for catalyst preparation and subsequent purification of the produced material”, suggests Prof. Albert Nasibulin of Skoltech. “Now, when the mechanism guiding the nano-materials growth without catalysts is understood, the next step is controlled synthesis of pure nano-wires with specific properties for their mass application”.

The results have been recently published in the scientific journal Nano Letters.

Rackauskas, H. Jiang, J. B. Wagner, S. D. Shandakov, T. W. Hansen, E. I. Kauppinen, and A. G. Nasibulin. In Situ Study of Noncatalytic Metal Oxide Nanowire Growth. Nano Letters. Article ASAP DOI: 10.1021/nl502687s. (http://dx.doi.org/10.1021/nl502687s)

 

* The Skolkovo Institute of Science and Technology (Skoltech) is a private graduate research university in Skolkovo, Russia, a suburb of Moscow. Established in 2011 in collaboration with MIT, Skoltech educates global leaders in innovation, advance scientific knowledge, and foster new technologies to address critical issues facing Russia and the world. Applying international research and educational models, the university integrates the best Russian scientific traditions with twenty-first century entrepreneurship and innovation.

 

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