Issue 1, 2015

Squaraine-sensitized composite of a reduced graphene oxide/TiO2 photocatalyst: π–π stacking as a new method of dye anchoring

Abstract

We synthesized a near infra-red (NIR)-absorbing squaraine dye (VJ-S) showing strong absorption and emission maxima at 684 and 704 nm, respectively, with a high molar extinction coefficient (ε) of 1.277 × 105 M−1 cm−1 and a band gap of 1.77 eV. Its oxidation and reduction potentials were found to be 0.889 and −0.795 V, respectively, with HOMO and LUMO levels of −5.21 and −3.53 eV, respectively. We also prepared the self-assembled core/shell nanocomposite r-NGOT, where TiO2 is the core and reduced nano-sized graphene oxide (r-NGO) is the shell. When VJ-S was anchored on r-NGOT, it showed π–π stacking with r-NGO, which is confirmed by Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and electron energy loss spectroscopy. The optical absorption spectrum of the VJ-S/r-NGOT nanocomposite measured with diffuse reflectance UV/visible absorption spectroscopy covers the whole range of visible light wavelengths up to 800 nm. The photocatalytic activity of VJ-S/r-NGOT at visible light wavelengths (λ > 420 nm) is much higher than that of r-NGOT alone.

Graphical abstract: Squaraine-sensitized composite of a reduced graphene oxide/TiO2 photocatalyst: π–π stacking as a new method of dye anchoring

Supplementary files

Article information

Article type
Paper
Submitted
20 Aug 2014
Accepted
28 Oct 2014
First published
29 Oct 2014

J. Mater. Chem. A, 2015,3, 232-239

Squaraine-sensitized composite of a reduced graphene oxide/TiO2 photocatalyst: π–π stacking as a new method of dye anchoring

K. L. V. Joseph, J. Lim, A. Anthonysamy, H. Kim, W. Choi and J. K. Kim, J. Mater. Chem. A, 2015, 3, 232 DOI: 10.1039/C4TA04313H

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