Synthesis of solar and visible-light-active highly ordered titania nanotube arrays (TNTS) for photocatalytic applications / Sim Lan Ching
The present contribution work focused on the development of solar-light and visible light responsive binary and ternary TiO2 nanotube arrays (TNTs) based composite photocatalysts. The developed photocatalysts were implemented for the competent removal of dye and phenolic derivative from the liqui...
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| Format: | Thesis |
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2015
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| Online Access: | http://studentsrepo.um.edu.my/7724/ http://studentsrepo.um.edu.my/7724/1/Thesis_Sim_Lan_Ching_260315.pdf |
| Summary: | The present contribution work focused on the development of solar-light and visible
light responsive binary and ternary TiO2 nanotube arrays (TNTs) based composite
photocatalysts. The developed photocatalysts were implemented for the competent
removal of dye and phenolic derivative from the liquid waste. The implication was also
extended for the photocatalytic conversion of CO2 and H2O to light hydrocarbon. The
binary composite was achieved by mashing-up the semiconductor oxides namely nickel
oxide (NiO) and tin oxide (SnO2) with TNTs through impregnation route. The
morphological analysis revealed that both of the binary composite are bunches free, self
organized and highly ordered with better geometry. The inclusion of semiconductor
oxides onto TNTs significantly promoted the shift towards the visible light spectrum
than that of the unmodified TNTs. The same was reflected in the solar-light-driven
photocatalytic degradation of prominent cationic dye solution, methylene blue (MB)
which was adopted as model pollutant for the binary composite with varied loading.
However, the increasing loading of both NiO and SnO2 did not exert significant effect
on the degradation efficiency of MB. The visible light development was approached
further by including the noble metals and conducting carbon materials. This led to the
formation of ternary composite, bound the localized surface plasmon resonance (LSPR)
and efficient electron transport endorsed by Ag and GO, respectively. The light source
was truncated to artificial visible light to eliminate the unsteady illumination conditions
as seen in solar spectrum. Implicit microscopic and spectroscopic techniques
substantiated the significance of the presence of Ag as nanoparticles (NPs) and the role
of GO in the ternary composite. The ternary exhibited a more appreciable red shift
towards the visible range and plunged the recombination of the electron-hole pair
compared to that of the binary. The photocatalytic investigation was carried out by
degrading MB and additionally chlorinated compound, 2-chlorophenol (2-CP)comprehensively along with their uniqueness in the degradation mechanism. The
reusability studies showed a deprived performance for MB degradation than that of 2-
CP, due to the chemisorption of MB. The successful results from our continuous work
motivated us to further explore the possibility of combining graphene (RGO) and
platinum (Pt) for a complicated gas phase conversion of carbon dioxide (CO2) to light
hydrocarbon under visible light irradiation. This ternary composite was synthesized by
depositing rapid thermally reduced GO over the surface of TNTs which was
predeposited with Pt. The resulting composite demonstrated a stunning visible light
absorption over the others. The prepared composite exhibited its accomplishment by
energetically photoreacting CO2 with H2O for the production of methane. This
synergetic CH4 production rate was attributed predominantly to the coexistence of RGO
and Pt which efficiently prolonged the lifetime of the photoinduced electrons and
extended the visible light response. Thus the present thesis enlightened and overcame
with much promising composite photocatalysts that upbeat the limitations experienced
by most of the conventional photocatalysts. It also provided a demanding sustainable
and greener solution for environmental cleanup and greenhouse gas reduction through
alternative fuel generation. |
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