3.3 Partial Oxidation
31
nanocatalysts depicted 75% yield of H 2 and 100% conversion in 24 h by partial
oxidation of isooctane [12].
3.4 Photocatalytic Activation
Photocatalytic activation of different hydrocarbons and their derivatives for generation of H 2 involves the extensive use of nanotechnology.
VO 2 is recognized as semiconductor with 0.7 eV bandgap, and this ability makes
it a promising candidate for the photocatalysis. Wang et al. reported a body-centeredcubic, nanostructured VO 2 , with remarkable photocatalytic activity for the generation
of hydrogen from ethanol and water mixture. This ability of the VO 2 nanostructures can be attributed to their very high optical bandgap (∼2.7 eV). These nanostructures were prepared by thermal oxidation process; the nanostructures of VO 2
were deposited on Si substrate. The Si substrate was selected because it has low
substrate temperature for producing extensive arrays of aligned nanorods and nanostructures of VO 2 (also for other metal oxides) on its surface. The prepared nanostructures were studied with SEM, TEM, XRD, electron energy loss spectrometry
(EELS), Rutherford backscattering spectrometry (RBS), and selected area (electron)
diffraction (SAD). The VO 2 nanostructures depicted the quantum yield of ∼38.7%
when fabricated and utilized as nanorods. The production rate of hydrogen can be
improved by adjusting the UV-incident angle on VO 2 nanorods (aligned in the form
of film). By correctly adjusting the angle of incident UV light with power density
of ∼27 m W/cm
2 , a high hydrogen production rate of 800 mmol/m
2 h
−1 is achieved
[13].
Pt/TiO 2 (B) nanofibers are noted for their photocatalytic activity in the production
of hydrogen from hydrocarbons. In a study, they are used for the generation of H 2
from neat ethanol. For the synthesis of Pt/TiO 2 (B) nanofibers, firstly, nanofibers of
H 2 Ti 3 O 7 were synthesized via hydrothermal process in NaOH at 130 °C followed
by acidic wash and subsequent drying at 110 °C. Afterward, H 2 Ti 3 O 7 nanofibers
were calcined at 300 °C which resulted in the development of TiO 2 (B) nanofibers.
Later the Pt was impregnated to these fibers. It was observed that with the increase in
calcined temperature by 100 °C, the crystallinity of the TiO 2 (B) nanofibers improved
whereas the dimension and morphology of the fibers remained same. The nanofibers
were characterized with field-emission scanning electron microscope (FE-SEM),
TEM, and Raman spectroscopy. The FE-SEM shows that many of the H 2 Ti 3 O 7 and
TiO 2 (B) nanofibers are tightly held together in the form of fiber bundle. The study
showed that the catalyst which was calcined at 400 °C has the H 2 production rate
similar to the standard P-25 TiO 2 whereas the catalysts which were calcined at above
or below 400 °C had shown comparatively poor results [14].
TiO 2 nanofilms decorated with Pt are also involved in the photocatalytic generation of H 2 from methanol gas. TiO 2 films were developed with tetrabutyl orthotitanate in ethanol followed by the addition of chlorohydric acid. The films were
fabricated by spin coating method on the surface of quartz and calcined at 400 °C.
31
nanocatalysts depicted 75% yield of H 2 and 100% conversion in 24 h by partial
oxidation of isooctane [12].
3.4 Photocatalytic Activation
Photocatalytic activation of different hydrocarbons and their derivatives for generation of H 2 involves the extensive use of nanotechnology.
VO 2 is recognized as semiconductor with 0.7 eV bandgap, and this ability makes
it a promising candidate for the photocatalysis. Wang et al. reported a body-centeredcubic, nanostructured VO 2 , with remarkable photocatalytic activity for the generation
of hydrogen from ethanol and water mixture. This ability of the VO 2 nanostructures can be attributed to their very high optical bandgap (∼2.7 eV). These nanostructures were prepared by thermal oxidation process; the nanostructures of VO 2
were deposited on Si substrate. The Si substrate was selected because it has low
substrate temperature for producing extensive arrays of aligned nanorods and nanostructures of VO 2 (also for other metal oxides) on its surface. The prepared nanostructures were studied with SEM, TEM, XRD, electron energy loss spectrometry
(EELS), Rutherford backscattering spectrometry (RBS), and selected area (electron)
diffraction (SAD). The VO 2 nanostructures depicted the quantum yield of ∼38.7%
when fabricated and utilized as nanorods. The production rate of hydrogen can be
improved by adjusting the UV-incident angle on VO 2 nanorods (aligned in the form
of film). By correctly adjusting the angle of incident UV light with power density
of ∼27 m W/cm
2 , a high hydrogen production rate of 800 mmol/m
2 h
−1 is achieved
[13].
Pt/TiO 2 (B) nanofibers are noted for their photocatalytic activity in the production
of hydrogen from hydrocarbons. In a study, they are used for the generation of H 2
from neat ethanol. For the synthesis of Pt/TiO 2 (B) nanofibers, firstly, nanofibers of
H 2 Ti 3 O 7 were synthesized via hydrothermal process in NaOH at 130 °C followed
by acidic wash and subsequent drying at 110 °C. Afterward, H 2 Ti 3 O 7 nanofibers
were calcined at 300 °C which resulted in the development of TiO 2 (B) nanofibers.
Later the Pt was impregnated to these fibers. It was observed that with the increase in
calcined temperature by 100 °C, the crystallinity of the TiO 2 (B) nanofibers improved
whereas the dimension and morphology of the fibers remained same. The nanofibers
were characterized with field-emission scanning electron microscope (FE-SEM),
TEM, and Raman spectroscopy. The FE-SEM shows that many of the H 2 Ti 3 O 7 and
TiO 2 (B) nanofibers are tightly held together in the form of fiber bundle. The study
showed that the catalyst which was calcined at 400 °C has the H 2 production rate
similar to the standard P-25 TiO 2 whereas the catalysts which were calcined at above
or below 400 °C had shown comparatively poor results [14].
TiO 2 nanofilms decorated with Pt are also involved in the photocatalytic generation of H 2 from methanol gas. TiO 2 films were developed with tetrabutyl orthotitanate in ethanol followed by the addition of chlorohydric acid. The films were
fabricated by spin coating method on the surface of quartz and calcined at 400 °C.