The Influence of La Doping on Structural, Optical …
377
Table 6 The rates (υ H2 ) of
photocatalytic hydrogen
evolution in the presence of
photocatalysts
Sample
TiO 2
1La/TiO 2
2La/TiO 2
υ H2 × 10 −7 , mol/min
3.3
4.7
5.6
evolution is caused by photocatalytic water reduction involving TiO 2 and La/TiO 2
in the presence of co-catalyst Pd/SiO 2 and an electron donor (ethanol).
As can be seen from Fig. 11 and Table 6, the rate of photocatalytic H 2 production
in the presence of La/TiO 2 composites is 1.4–1.7 times higher compared to pure
titanium dioxide.
Our results are in good agreement with the fact that La decreases the recombination rate of photogenerated charges by collecting electrons from TiO 2 while holes
remained on TiO 2 [50]. In combination with the other structural and textural factors
noted above, La/TiO 2 composites demonstrated higher photoactivity in the reaction
of Safranin T photodestruction and H 2 photoproduction in comparison with pure
TiO 2 .
4 Conclusions
Mesoporous nanocomposite materials La/TiO 2 with different lanthanum contents
were synthesized by sol–gel method. It was established that the content of rutile in
the La/TiO 2 composites is twice higher compared to pure TiO 2 . It was found that
doping with La leads to a decrease in the anatase crystallite sizes from 10 to 8 nm and
rutile crystallite sizes from 7 to 5 nm. The specific surface area of La/TiO 2 composites
increases by two times compared with pure TiO 2 . The absorption edge of La/TiO 2
samples shifts to shorter wavelengths (blue shift) compared with pure TiO 2 . The
banggap energy values of the samples increase compared with pure titanium dioxide.
It was found that La/TiO 2 nanocomposites exhibit higher photocatalytic activity than
pure TiO 2 in Safranine T photodestruction (decolorization) and H 2 photoproduction.
The enhanced photocatalytic activity of the La/TiO 2 samples is mainly determined
by a decrease in the recombination rate of photogenerated charges, small particle
size, and larger surface area due to the doping with La.
Acknowledgements Support of the National Academy of Sciences of Ukraine under the Research
Programs “Development of alternative methods for the preparation of nanosized oxide catalysts and
composites based on Mo, Ti, Zr, Nb and Sn” 2018–2022, “Fundamental problems of nanostructured systems, nanomaterials and nanotechnologies” 2016–2020 and VC-180 “Optical, electrophysical and structural properties of disordered molecular systems and nanocomposites” 2016–2020 is
gratefully acknowledged.
Availability of data and materials
The present research results have not been published before. Data and Materials are all in the
main text, figures, and tables. Compliance with ethical standards.
Conflict of interests The authors declare that they have no competing interests.
377
Table 6 The rates (υ H2 ) of
photocatalytic hydrogen
evolution in the presence of
photocatalysts
Sample
TiO 2
1La/TiO 2
2La/TiO 2
υ H2 × 10 −7 , mol/min
3.3
4.7
5.6
evolution is caused by photocatalytic water reduction involving TiO 2 and La/TiO 2
in the presence of co-catalyst Pd/SiO 2 and an electron donor (ethanol).
As can be seen from Fig. 11 and Table 6, the rate of photocatalytic H 2 production
in the presence of La/TiO 2 composites is 1.4–1.7 times higher compared to pure
titanium dioxide.
Our results are in good agreement with the fact that La decreases the recombination rate of photogenerated charges by collecting electrons from TiO 2 while holes
remained on TiO 2 [50]. In combination with the other structural and textural factors
noted above, La/TiO 2 composites demonstrated higher photoactivity in the reaction
of Safranin T photodestruction and H 2 photoproduction in comparison with pure
TiO 2 .
4 Conclusions
Mesoporous nanocomposite materials La/TiO 2 with different lanthanum contents
were synthesized by sol–gel method. It was established that the content of rutile in
the La/TiO 2 composites is twice higher compared to pure TiO 2 . It was found that
doping with La leads to a decrease in the anatase crystallite sizes from 10 to 8 nm and
rutile crystallite sizes from 7 to 5 nm. The specific surface area of La/TiO 2 composites
increases by two times compared with pure TiO 2 . The absorption edge of La/TiO 2
samples shifts to shorter wavelengths (blue shift) compared with pure TiO 2 . The
banggap energy values of the samples increase compared with pure titanium dioxide.
It was found that La/TiO 2 nanocomposites exhibit higher photocatalytic activity than
pure TiO 2 in Safranine T photodestruction (decolorization) and H 2 photoproduction.
The enhanced photocatalytic activity of the La/TiO 2 samples is mainly determined
by a decrease in the recombination rate of photogenerated charges, small particle
size, and larger surface area due to the doping with La.
Acknowledgements Support of the National Academy of Sciences of Ukraine under the Research
Programs “Development of alternative methods for the preparation of nanosized oxide catalysts and
composites based on Mo, Ti, Zr, Nb and Sn” 2018–2022, “Fundamental problems of nanostructured systems, nanomaterials and nanotechnologies” 2016–2020 and VC-180 “Optical, electrophysical and structural properties of disordered molecular systems and nanocomposites” 2016–2020 is
gratefully acknowledged.
Availability of data and materials
The present research results have not been published before. Data and Materials are all in the
main text, figures, and tables. Compliance with ethical standards.
Conflict of interests The authors declare that they have no competing interests.