Abstract
TiO2/reduced graphene oxide (rGO) nanocomposites with two different TiO2 particle sizes were synthesized by a facile hydrothermal method using two different source materials of Ti: tetrabutyl titanate (TBT) and commercial TiO2 powder (P25). For respective series with the same source materials, we investigated additions that optimized the nonlinear optical properties (NLO) and optical limiting (OL) performances, and we explored the relationships between structural diversity and performance. Several characterization techniques, including X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis) were conducted to confirm the microstructures and chemical states of as-prepared materials. This indicated the existence of the Ti–O–C bond between rGO sheets and TiO2 particles and the reduction from precursor graphene oxide (GO) to rGO. The results of UV-Vis spectra revealed that the TiO2/rGO nanocomposites showed smaller band gaps than bare TiO2. A nanosecond open-aperture Z-scan technique at 1064 nm was applied to investigate NLO and OL properties. TiO2/rGO nanocomposites exhibited enhanced NLO and OL performances, arising from synergistic effects, compared to individual components. The TBT series samples performed better than the P25 series, presumably relevant to dimensional effects.
Highlights
Nowadays, because of their good monochromaticity, collimation, high brightness, and good coherence, lasers have been widely used in many respects of our lives
Knowing that particle sizes of TiO2 will cause differences in photocatalytic H2-production activity [27], in this study we investigated the effects of different TiO2 particle sizes of TiO2/reduced graphene oxide (rGO) nanocomposites on nonlinear optical (NLO) properties and optical limiting (OL) performances
No apparent peaks corresponding to rGO were observed in the X-ray powder diffraction (XRD) patterns of TiO2/rGO nanocomposites, probably because the characteristic peak of rGO at about 25◦ was covered by the characteristic peak of anatase at 25.3◦ [32]
Summary
Because of their good monochromaticity, collimation, high brightness, and good coherence, lasers have been widely used in many respects of our lives. Optical limiting materials are capable of exhibiting significant promise for laser protection because of their nonlinear optical (NLO) properties [1,2,3,4]. There are some remaining oxygen-containing groups in reduced graphene oxide (rGO) sheets. The existence of remaining groups can ensure attachment between rGO and other optical limiting (OL) materials [15,16]. Compared to graphene oxide (GO), reduced graphene oxide (rGO) partially renovates the π-electron conjugation and shows stronger nonlinear optical properties and optical limiting performances. Lim et al [19] investigated graphenes, which were spread out in varied dispersants, and found they could exhibit broadband nonlinear absorption as a result of an intense matrix effect, for which there was remarkable optical limiting clamp threshold of 10 mJ/cm. The research of Kavitha et al [20] found that reduced graphene oxide–zinc oxide nanohybrids exhibited OL enhancements compared to graphene oxide (GO) and ZnO
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