Abstracts Book - IMRC 2018

• SF2-O030 Invited Talk
STRUCTURAL ENGINEERING AND BAND GAP TUNABLE
PHOTOCATALYTIC PROPERTIES OF COLLOIDAL TIO2
NANOPARTICLES
Jyoti Bansal 1,2 , Ak Hafiz 3 , Shailesh Sharma 1
1 CSIR-National Physical Laboratory, Advanced Materials and Devices, India. 2 Jamia Millia
Islamia, Centre for Nanoscience and Nanotechnology,, India. 3 Jamia Millia Islamia, Centre for
Nanoscience and Nanotechnology, India.
Titanium dioxide (TiO 2 )-based photocatalysts are most frequently studied as
they are stable, non-toxic, readily available and highly efficient. However, the
relatively wide band gap of TiO 2 and charge recombination between the TiO 2
electrode and the electrolyte significantly limits its use under visible
light. Doping of TiO 2 with the proper kind of metal ions could reduce the charge
recombination and narrow the band gap of TiO 2 which eventually improves its
photocatalytic properties. In the present work, synthesis of TiO 2 nanoparticles
has been carried out using a combination of sol-gel & hydrothermal method and
the photocatalytic activities of TiO 2 nanoparticles doped with Chromium and
Copper metals individually are compared. Here, the photocatalytic degradation
of Malachite Green (MG) Dye has been studied using the pure- and doped TiO 2
respectively. It has been observed that the Cu-TiO 2 composites show better
photocatalytic activities as compared to pure- TiO 2 and Cr-TiO 2 composites
respectively. The increased incorporation of Cr3+ and Cr4+ ions in the TiO 2
matrix might screen the photocatalytic activity of Cr-TiO 2 as compared to Cu-
TiO 2 composites. On the other hand, the modification of the chemical structure
of titanium dioxide by Cu doping allows moving the photocatalytic activity of
titanium dioxide towards visible light. The results indicate that films doped with
10% Cu exhibit the highest UV and visible light photocatalytic activity. The
enhanced photoactivity of the Cu-TiO 2 composite sample can be attributed to a
combined effect of improved adsorption of MG dye on its surface, improved
visible light absorption and thus increased lifetime of the charge carriers,
resulting the transfer of electrons the conduction band of Cu-TiO 2 to the surface
states of MG dye which ultimately results in 88% mineralization of the MG dye.
On the contrary, it is found that the undoped TiO 2 leads to rapid decoloration of
the MG dye as compared to the Cr-doped one which could be possibly due to
the increased coverage of the TiO 2 surface by Cr-metal thus leading to a
decrease in surface adsorption sites predicted to be available to the dye. This
eventually decreases the penetration depth of the light thus preventing the