Enhanced Absorption and Photoemission from TiO2 Nanowire/Graphene Oxide Thin-Film Heterostructure
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Vertically oriented TiO2 nanowires (NWs) have been fabricated on graphene oxide (GO) thin film (TF) using a catalytic free growth technique called glancing-angle deposition. GO TF was spin coated on Si substrate at different rotation speeds and the surface roughness measured by atomic force microscopy. Field-emission scanning electron microscopy confirmed formation of a heterostructure consisting of GO TF with thickness of ∼ 300 nm and TiO2 NWs with length of ∼ 800 nm. Selected-area electron diffraction analysis in transmission electron microscopy showed that the TiO2 NWs grown on the GO TF were amorphous in nature, as confirmed by x-ray diffraction analysis. A bandgap close to ∼ 4.1 eV was obtained for GO TF, whereas a main band transition edge at 3.3 eV was obtained for a TiO2 NW/GO TF heterostructure sample, related to TiO2. Two subband transitions at 2.9 eV and 2.4 eV were also observed for the heterostructure sample, corresponding to oxygen and Ti3+ defect transitions for the TiO2 NWs. Enhanced photoluminescence and absorption were observed for the heterostructure sample as compared with the GO TF sample.
KeywordsGLAD nanowires photoluminescence thin film TiO2 graphene oxide
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The authors are grateful to SAIF, NEHU Shillong for TEM analysis, NCPRE, IIT Bombay for FE-SEM, Dr. Thiyam David Singh, Department of Chemistry, NIT Manipur for PL measurements, Dr. Debarun Dhar Purkayasta, Department of Physics, NIT Nagaland for providing the spin coater, and Dr. Ardhendu Saha, Department of Electrical Engineering, NIT Agartala, India for providing optical measurement facility, as well as NIT Nagaland for financial support.
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