One-Dimensional-Like Titania/4'-Pentyl-4-Biphenylcarbonitrile Composite Synthesized Under Magnetic Field and its Structure-Photocatalytic Activity Relationship

• Published in: Frontiers in chemistry 2018-09, Vol.6, p.370-370
• Main Authors: Abu Bakar, Nur I, Chandren, Sheela, Attan, Nursyafreena, Leaw, Wai L, Nur, Hadi
• Format: Article
• Language: English
• Subjects: Chemistry; electron mobility; liquid crystal; magnetic field; one-dimensional-like titania composite; photocatalytic activity
• ISSN: 2296-2646; 2296-2646
• DOI: 10.3389/fchem.2018.00370

The demonstration of the structure-properties relationship of shape-dependent photocatalysts remains a challenge today. Herein, one-dimensional (1-D)-like titania (TiO ), as a model photocatalyst, has been synthesized under a strong magnetic field in the presence of a magnetically responsive liquid crystal as the structure-aligning agent to demonstrate the relationship between a well-aligned structure and its photocatalytic properties. The importance of the 1-D-like TiO and its relationship with the electronic structures that affect the electron-hole recombination and the photocatalytic activity need to be clarified. The synthesis of 1-D-like TiO with liquid crystal as the structure-aligning agent was carried out using the sol-gel method under a magnetic field (0.3 T). The mixture of liquid crystal, 4'-pentyl-4-biphenylcarbonitrile (5CB), tetra- -butyl orthotitanate (TBOT), 2-propanol, and water, was subjected to slow hydrolysis under a magnetic field. The TiO -5CB took a well-aligned whiskerlike shape when the reaction mixture was placed under the magnetic field, while irregularly shaped TiO -5CB particles were formed when no magnetic field was applied. It shows that the strong interaction between 5CB and TBOT during the hydrolysis process under a magnetic field controls the shape of titania. The intensity of the emission peaks in the photoluminescence spectrum of 1-D-like TiO -5CB was lowered compared with the TiO -5CB synthesized without the magnetic field, suggesting the occurrence of electron transfer from 5CB to the 1-D-like TiO -5CB during ultraviolet irradiation. Apart from that, direct current electrical conductivity and Hall effect studies showed that the 1-D-like TiO composite enhanced electron mobility. Thus, the recombination of electrons and holes was delayed due to the increase in electron mobility; hence, the photocatalytic activity of the 1-D-like TiO composite in the oxidation of styrene in the presence of aqueous hydrogen peroxide under UV irradiation was enhanced. This suggests that the 1-D-like shape of TiO composite plays an important role in its photocatalytic activity.