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S. Nahirniak et al.
11]; controlling the operating temperature [12]; and using particles of different
morphology [13].
14.1.2 Nanostructured SnO 2 Layers for Their Use in Gas
Sensors
Parameters of SnO 2 -based gas sensors (stability, sensitivity, selectivity, and response
time) can be greatly improved by reducing the size of SnO 2 particles to nanometer
dimensions and by using the single-crystalline SnO 2 nanoparticles of different
morphology (0D and 1D). The latter will significantly improve the sensor response
due to less defects in crystals, large specific surface area, and bigger surface to
volume ratio of particles.
Nanocrystalline materials are characterized by the highest values of the sensor
signal through the high specific surface area and, thus, higher adsorption capacity
[5]. SnO 2 particles with a diameter of 10 ÷ 30 nm are capable to adsorb much larger
number of molecules of different gases than massive materials by reason of more
branched structure of their surface [14].
In addition to the crystallites’ size and the relationship between them, the ratio
of surface area to volume also has a great influence. The increase of it causes
significant changes in sensitivity of the sensor [15]. From this point of view, onedimensional (1D) nanostructures deserve special attention [16]. Semiconductor
1D nanostructures represent an important and broad class of nanosized wirelike
structures that can be rationally and predictably synthesized in the same crystalline
form with controlled chemical composition, diameters, length, and high-precision
doping levels [17, 18].
Nanoscale materials, with their large specific surface area and possible quantum
retention effects, show excellent mechanical, thermal, chemical, electrical, and
optical properties in contrast to their bulk analogues. Control of the determined
size, crystallinity, and composition of 1D nanostructures leads to the discovery
of their unique properties, thus enabling different applications that would not be
possible in the case of materials of massive dimension [19]. Among the various
1D nanostructures, semiconductor tin (IV) oxide nanostructures are particularly
interesting through their promising application in optoelectronic and electrical
devices due to good conductivity and transparency in the visible region.
With the use of 1D SnO 2 nanostructures as sensitive elements of gas sensors,
the following advantage is predicted: the morphology of one-dimensional materials
provides a high value of the specific surface area while maintaining their sufficient
chemical and thermal stability with minimal energy consumption and low mass.
High values of the specific surface area indicate that a significant part of atoms (or
molecules) will be concentrated on the surface. Thereby, the reaction between the
target gas and the chemically active chemisorbed molecules (O − , O 2− , H + , and
OH − ) becomes possible at low temperatures.
S. Nahirniak et al.
11]; controlling the operating temperature [12]; and using particles of different
morphology [13].
14.1.2 Nanostructured SnO 2 Layers for Their Use in Gas
Sensors
Parameters of SnO 2 -based gas sensors (stability, sensitivity, selectivity, and response
time) can be greatly improved by reducing the size of SnO 2 particles to nanometer
dimensions and by using the single-crystalline SnO 2 nanoparticles of different
morphology (0D and 1D). The latter will significantly improve the sensor response
due to less defects in crystals, large specific surface area, and bigger surface to
volume ratio of particles.
Nanocrystalline materials are characterized by the highest values of the sensor
signal through the high specific surface area and, thus, higher adsorption capacity
[5]. SnO 2 particles with a diameter of 10 ÷ 30 nm are capable to adsorb much larger
number of molecules of different gases than massive materials by reason of more
branched structure of their surface [14].
In addition to the crystallites’ size and the relationship between them, the ratio
of surface area to volume also has a great influence. The increase of it causes
significant changes in sensitivity of the sensor [15]. From this point of view, onedimensional (1D) nanostructures deserve special attention [16]. Semiconductor
1D nanostructures represent an important and broad class of nanosized wirelike
structures that can be rationally and predictably synthesized in the same crystalline
form with controlled chemical composition, diameters, length, and high-precision
doping levels [17, 18].
Nanoscale materials, with their large specific surface area and possible quantum
retention effects, show excellent mechanical, thermal, chemical, electrical, and
optical properties in contrast to their bulk analogues. Control of the determined
size, crystallinity, and composition of 1D nanostructures leads to the discovery
of their unique properties, thus enabling different applications that would not be
possible in the case of materials of massive dimension [19]. Among the various
1D nanostructures, semiconductor tin (IV) oxide nanostructures are particularly
interesting through their promising application in optoelectronic and electrical
devices due to good conductivity and transparency in the visible region.
With the use of 1D SnO 2 nanostructures as sensitive elements of gas sensors,
the following advantage is predicted: the morphology of one-dimensional materials
provides a high value of the specific surface area while maintaining their sufficient
chemical and thermal stability with minimal energy consumption and low mass.
High values of the specific surface area indicate that a significant part of atoms (or
molecules) will be concentrated on the surface. Thereby, the reaction between the
target gas and the chemically active chemisorbed molecules (O − , O 2− , H + , and
OH − ) becomes possible at low temperatures.