7 Applications Perspectives of Nanodispersed Chalcogenides of Transition. . .
111
Table 7.2 Values of the
width of the bandgap,
calculated theoretically for
some chalcogenides of
transferred metals [45]
Material Width of the Bandgap, eV
MoS 2
1,84
MoSe 2
1,60
WS 2
1,97
WSe 2
1,66
investigators. Unfortunately, the used them method of powerful bond couldn’t be
able to describe clearly the electron structure of molybdenum (IV) chalcogenides.
In 1973, another work was published. In this work, the authors used the method
of plane waves. The investigation had shown that the bandgap for MoS 2 was is not
less than 1 eV and it is not exactly 0,2 eV [29]. It was also shown that exciting
maximums are 2 eV. They are observed in the spectra of optical absorption and
related to d-orbitals of molybdenum. This allowed MoS 2 and similar compounds of
the elements of the 4-th group to be classified as a separate class of semiconductors.
These assumptions had been confirmed experimentally with the development of Xray methods [42].
The work with the measurement of angle dependence of X-ray spectra of
adsorption was published at the same time along with the work about data on
electron structure of MoS 2 , MoSe 2 , and WS 2 . The data on electron structure had
been obtained by the method of spherical waves [43, 44]. The authors also showed
that MoS 2 is a semiconductor with indirect bandgap in deadline.
The values of width of the band gap of some chalcogenides of transition
metals had been calculated theoretically in another work. The data are presented in
Table 7.2.
7.5 Conclusions
Photocatalysis currently is a branch of science that is rapidly evolving and can
contribute to solving many environmental and energy tasks in a world of growing
scientific progress. For this it is necessary to actively explore the properties
of those materials and compositions that can be used for obtaining effective
photocatalysts. Contradictory data have been published concerning the mechanisms
of photocatalytic reactions, and mainly titanium photocatalysts are researched.
Mechanisms of reaction with other photocatalysts have not been studied sufficiently.
Nanodispersed chalcogenides of transition metals in photocatalysis have a broad
range and therefore deserve separate detailed consideration. Special attention in
further studies should be given to obtaining film chalcogenides of transition metals
as the most promising for industrial use.
Acknowledgments The authors thank the National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” for the opportunity to carry out this research.
111
Table 7.2 Values of the
width of the bandgap,
calculated theoretically for
some chalcogenides of
transferred metals [45]
Material Width of the Bandgap, eV
MoS 2
1,84
MoSe 2
1,60
WS 2
1,97
WSe 2
1,66
investigators. Unfortunately, the used them method of powerful bond couldn’t be
able to describe clearly the electron structure of molybdenum (IV) chalcogenides.
In 1973, another work was published. In this work, the authors used the method
of plane waves. The investigation had shown that the bandgap for MoS 2 was is not
less than 1 eV and it is not exactly 0,2 eV [29]. It was also shown that exciting
maximums are 2 eV. They are observed in the spectra of optical absorption and
related to d-orbitals of molybdenum. This allowed MoS 2 and similar compounds of
the elements of the 4-th group to be classified as a separate class of semiconductors.
These assumptions had been confirmed experimentally with the development of Xray methods [42].
The work with the measurement of angle dependence of X-ray spectra of
adsorption was published at the same time along with the work about data on
electron structure of MoS 2 , MoSe 2 , and WS 2 . The data on electron structure had
been obtained by the method of spherical waves [43, 44]. The authors also showed
that MoS 2 is a semiconductor with indirect bandgap in deadline.
The values of width of the band gap of some chalcogenides of transition
metals had been calculated theoretically in another work. The data are presented in
Table 7.2.
7.5 Conclusions
Photocatalysis currently is a branch of science that is rapidly evolving and can
contribute to solving many environmental and energy tasks in a world of growing
scientific progress. For this it is necessary to actively explore the properties
of those materials and compositions that can be used for obtaining effective
photocatalysts. Contradictory data have been published concerning the mechanisms
of photocatalytic reactions, and mainly titanium photocatalysts are researched.
Mechanisms of reaction with other photocatalysts have not been studied sufficiently.
Nanodispersed chalcogenides of transition metals in photocatalysis have a broad
range and therefore deserve separate detailed consideration. Special attention in
further studies should be given to obtaining film chalcogenides of transition metals
as the most promising for industrial use.
Acknowledgments The authors thank the National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” for the opportunity to carry out this research.