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THE LABORATORY OF CHEMISTRY AND PHYSICS OF SENSOR AND SEMICONDUCTOR MATERIALS |
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| Materials for sensors Gaskov Alexander e-mail: gaskov@inorg.chem.msu.ru phone: +7 ( 495) 939-54-71 Nanocrystalline materials based on metal oxides for the detection of toxic and hazardous gases in the air. For
centuries, mankind has created a variety of machines to enhance its
features. Created devices for spacecraft missions to other planets ,
submarines to swim under water , people have learned to see in the dark
, consider the stars through a telescope and the smallest particles in
the microscope . However, in the field of artificial olfaction progress
is still quite modest . Not yet created a device which would be able to
compete in their sensitivity and selectivity with the dog's nose ,
which domesticated still in its infancy and continues to use to this
day. Meanwhile , the environment is becoming more aggressive , we live
in a manmade gases emissions , the risk of leakage of natural gas ,
which is let down in almost every home . It should be noted that the
major air pollutants , even as simple as carbon monoxide, nitrogen
oxides , ammonia , hydrogen sulfide is toxic at the concentration unit
in a million molecules . All this requires the creation of highly
miniaturized , highly sensitive and selective " electronic noses " for
early warning of the presence in the air of toxic or explosive gases .
sensorovEst material group hopes that the new materials developed at the Faculty of Chemical laboratory "Chemistry and physics of semiconductor and sensor materials " will substantially increase the artificial olfaction. The basis of such materials are semiconductor nanoparticles : tin oxide , indium or tungsten . Such a particle size between 3 and 10 nanometers are interesting because they have excellent ability to adsorb the molecules of the environment and to transmit information about the amount of adsorbed gases in the form of an electrical signal. Such properties of semiconductor surfaces have been known for a long time , but the main problem that needs to be solved is how to teach particle recognize dangerous molecules , amid a large number of substances is safe . TEM image of nanocrystalline oxide olovaChelovek this purpose uses a variety of chemical and biological receptors to identify the nature of pleasant and unpleasant odors.  Our laboratory has developed a technology of chemical modification of nanoparticles of semiconductors, grafting on the surface of synthetic receptors for directional change their reactivity . These receptors can be not only well-known clusters catalysts of platinum group metals or metal oxides , but also organic receptors on the basis of new macrocyclic compounds synthesized at the Chemistry Faculty . We succeeded in synthesizing modified nanoparticles and show that the nature of the receptors determines the specificity of the material, its ability to respond selectively to one or a group of dangerous gases.  sensing application layer microelectronic chipPonyatno that
enough for practical use to synthesize a compound , it is necessary to
learn to carry it on a microelectronic chip , a special substrate with
electrical contact system and heater. Such microelectronic device
developed by specialists of the Kurchatov Institute , they provide the
desired mode for sensor and largely responsible for its performance.A microelectronic chip , with the sensitive element on the basis of chemically modified nanoparticle is a key element of the gas detector . Several microelectronic chips based nanoparticles with different receptors that are configured for the detection of different molecules can be combined in one detector for analyzing gas mixtures. Such detectors based on 4 microelectronic chips created in cooperation with specialists from Tomsk enterprises " Senseriya " to analyze the major air pollutants and for medical purposes to analyze patients exhalation . Sensitivity detectors based on semiconductor nanoparticles can greatly increase , if you learn how to preallocate and concentrate hazardous gases. This new direction of the laboratory , together with our colleagues from the laboratory kinetics and catalysis , which are developing special adsorbents created highly sensitive multichannel detectors , in which each channel is set to extraction, concentration and  measurement of a certain group of toxic gases.
cooperation (for more info click here )
projects (for more info click here) RFBR 12 -03- 00524_a " The effect of light on the reactivity of nanocrystalline metal oxides coated with quantum dots" ( 2012 - 2014 )
The project aims to create nanocomposites based on nanocrystalline
oxide semiconductor sensitized nanocrystals (quantum dots) CdSe and
study their interactions with the gas phase under irradiation with
light. Fundamental objectives of the project are : (i) development of
methods for the directed synthesis of sensitized materials with
controlled crystallite size of 3-20 nm semiconductor matrix and CdSe
nanocrystals with size 2-6 nm; (ii) the establishment of patterns of
influence of irradiation with light in the visible spectrum on the
electrical properties and reactivity of nanocomposites by reacting with
oxygen and major air pollutants.
State . FTSTP contract № 11.519.11.1009 on " nanoheterogeneeous filamentary materials based on oxide semiconductor chemical sensors" (2012 - 2013 ) State . FTSTP contract № 11.519.11.6047 on " Create photo and gas sensing nanocomposites based on nanocrystalline oxide semiconductor sensitized A2B6 quantum dots " (2012 - 2013 ) Wide bandgap
semiconductors nanocrystals obtained SnO2, In2O3
and ZnO and narrow-gap
CdTe and CdSe, of interest to create a sensitized materials. The
technique of immobilization of quantum dots and nanocomposites obtained
photosensitive SnO2/CdSe and ZnO/CdSe. Such
materials can be used for
gas sensors operating without heating at room temperature under light
conditions . The presence of a sensitizer in semiconductor oxides
emission diodes allow the use of low power to achieve the following
objectives : lowering the resistance of materials, initiate chemical
reactions of molecules detected gas from the semiconductor surface,
the desorption of the reaction products without thermal heating at room
temperature.
State . FTSTP contract № 11.519.11.1009 on " Nanoheterogeneeous filamentary materials based on semiconducting oxides for chemical sensors " (2012 - 2013 ) New
materials , which are whisker SnO2 and ZnO
n-type conductivity ,
which is immobilized on the surface of clusters of CuO (PdO) p-type
conductivity. Such materials have a high specific surface area, high
adsorption capacity and the electrical properties depend strongly on
the composition of the atmosphere. The presence of pn junctions
significantly reduces the flow channel dimensions of the charge
carriers in the filaments and gives hope for a high sensitivity to the
presence of materials nanoheterogeneeous air gas molecules oxidants or
reducing agents.
RFBR 12 -03- 12001_ofi_m "Creating chemically hazardous gas detectors organophosphorus and nitrogen-containing substances on the basis of selective nanocrystalline semiconductors and molecular sieve hubs " (2012 - 2013 )
The project aims to develop methods of detecting hazardous products in
the air based on the technology of combining semiconductor detectors
with preconcentration of target molecules on molecular sieves . Methods
have been developed and synthesized nanocrystalline semiconducting
metal oxides , are chemically modified catalytic clusters having
selectivity to organophosphorus and nitrogen - containing molecules.
Synthesis of nanocrystalline oxides SnO2, In2O3,
ZnO with a crystallite
size controlled in the range of 3-20 nm performed by chemical vapor
deposition from colloidal solutions . Catalytic clusters Au, PtO2,
PdO,
RuO2, CuO, NiO supported on the surface of the
semiconductor matrix
during synthesis or nanocrystalline oxide by an impregnation method .
For selective concentration of target gases complex synthesized
mesoporous aluminosilicates ( zeolite analogues ) with different pore
structure with a system of controlled pore diameter from 30 A to 5.5 A.
The properties of the materials of sensor measurements are carried out
on the bench for a fully automated detection of H2S
and NH3. As used
organophosphorus desired product dimethylmethylphosphonate (DMMP), a
nitrogen-containing substance used as unsymmetrical dimethylhydrazine
(UDMH) .
Designed and developed by the laboratory stand , which allows to control the concentration of the target gas in the air in the range of 20 ppb - 2 ppm. A laboratory prototype multisensor system with preconcentration of target gases , which has been tested at 100 ppb DMMP detection and 0.1mg/m3 UDMH . RFBR 12 -03- and - 31446_mol " Active sites on the surface of nanocrystalline metal oxides and the specificity of their interaction with nitrogen-containing organic compounds " (2012 - 2013 )
For the synthesis of nanocomposites based on nanocrystalline SnO2
impregnation techniques used (including wetness ) , chemical methods "
prishivki " modifier covalent bond. Selected synthesis methods allow to
control the composition and content of the resulting materials used
modifiers (SiO2, Al2O3,
Cr2O3, Nb2O5,
Au). The resulting nanocomposites
were characterized complex techniques - XRD, BET , TPR - H2, TPD -NH3.
Composition highly sensitive materials identified by elemental
analysis, - an X-ray fluorescence spectrometry for total internal
reflection. Characterized by electrical and sensory properties of
materials. Shown that the system SnO2-SiO2
method " prishivki " organic
precursor to the surface modifier can effectively control the
quantitative composition of the resulting samples. It was found that
the growth of the content up to 3 % SiO2 by
weight. samples
simultaneously with increasing the heat treatment temperature to 700 °
C accompanied by increased sensitivity to touch SB .
RFBR 11 -03- 12111_ofi " Photoconductivity and sensory properties of nanocomposites based on hybrid semiconductor matrix sensitized with quantum dots and organometallic compounds " ( 2011 - 2012)
The project with a wide range of modern physico-chemical methods
established structure of hybrid organic -inorganic nanostructured
materials . First conducted a systematic study of the influence of
organic complexes of copper (II) by the amount of sensory response of
tin dioxide in the gas phase . It is shown that administration of these
modifiers results in an increase SnO2 sensor response with respect to
H2S and ethanol vapor in air. It was shown that the formation of a
semi-permeable silicone matrix structure on the surface of SnO2
significantly alters sensory characteristics of tin dioxide . Record
values obtained sensor response to NO2 at the maximum allowable
concentrations ( <100 ppb in air) . It is shown that immobilized
crown arilnaftalimidov N- derivatives on the surface of single crystals
of SnO2 affords systems which are sensitive to
cations Mg2+ and Ca2+
ions in solution. The technique allows to immobilize molecules
fluorophores without loss of chemosensory properties.
Coordinate projects with the framework research program EC and Russia «Surface ionization and novel concepts in nano-MOX gas sensors with increased Selectivity, Sensitivity and Stability for detection of low concentrations of toxic and explosive agents CP-FP 247768 S3 / 02.527.11.0008.» (2009 - 2012) Development and testing of multi- gas detectors of new generation, including semiconductor sensors , combined with the systems of the pre-separation and concentration of molecules on the basis of new chemically modified nanocrystalline metal oxides with high selective sensitivity to toxic and explosive products in the air , including CO, NO2, H2S and NH3.We're sorry, but this page is under construction.
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