Synthesis, Optical, Electrical And Catalytic Properties Of Titanium-Based Oxides Materials And Their Sodium-Doped Derivatives
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Date
2016-01
Authors
Chew, Ker Yin
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Barium titanate (BaTiO3) and barium nickel titanate (Ba2NiTi5O13) were
synthesized via sol-gel method. Mechanism of formation of BaTiO3 and Ba2NiTi5O13
was proposed. The effect of Na doping on structural composition and surface
morphology of 3 titanium-based oxides (i.e. titanium dioxide (TiO2), BaTiO3 and
Ba2NiTi5O13) were investigated. The phase structures of TiO2, BaTiO3 and
Ba2NiTi5O13 i.e. anatase, cubic and monoclinic respectively were sustained after Na
doping. This indicates that the substitution of Na on Ti atom was a surface
phenomenon. The morphology transformation of Na-doped BaTiO3 particles was
observed. Hammett indicator showed that the Na-doped Ba2NiTi5O13 has the highest
basicity. From BET result, the Na-doped Ba2NiTi5O13 showed the largest specific
surface area as compared to Na-doped BaTiO3 and Na-doped TiO2. The application of
these titanium-based oxides as the fillers in polyvinyl alcohol (PVA) was investigated.
The structural, thermal, electrical and optical properties of these polymer composites
were studied. The x-ray diffraction (XRD) and differential scanning calorimetry
(DSC) results showed that the polymer composites were semicrystalline with high
amorphous region and low Tg values. The 0.3 mol % of Na-doped of PVA/TiO2,
PVA/BaTiO3 and PVA/Ba2NiTi5O13 showed the conductivity of 9.540x10-7, 1.667x10-
7 and 2.401x10-8 S cm-1, respectively. The optical band gaps of PVA based polymer
composites showed that they are semiconducting. The optical band gaps were blue
shifted when increasing the amount of fillers loading as well as increasing the amount
of Na-dopants. The obtained TiO2, BaTiO3 and Ba2NiTi5O13 and their respective Nadoped derivatives were also utilized as heterogeneous catalysts for the
transesterification of palm cooking oil. Optimal parameters were 5 wt/v % of catalyst
loading, oil to methanol volume ratio of 12:1 and 2 hours of reaction at 150 °C.
Amongst the catalysts, Na-doped Ba2NiTi5O13 showed the highest % of methyl esters
(ME) yield (96.0 %), whereas TiO2 showed the lowest (76.3 %). The % of methyl ester
(ME) yield is attributed to the basicity and pore size of the respective catalysts.
Description
Keywords
Titanium-based oxides