Materials Today Communications
Fabrication of ZnO-RGO nanorods by electrospinning assisted hydrothermal method with enhanced photocatalytic activity
Introduction
Zinc oxide (ZnO) is one of the most popular and effective photocatalytic semiconductors with a direct bandgap around 3.4 eV. and a large exciton binding energy of 60 meV [1]. ZnO nanostructures can be produced using various physical and chemicals methods [2]. Among these techniques, Xiabion et al. [3] reported ZnO nanorods fabricated on glass substrates via a novel electrospinning assisted hydrothermal method. The hydrothermal route is found to be attractive because of its advantages of simple manipulation, low temperature and potential for scale [4]. In addition, the electrospinning technique has drawn much attention in recent years owing to its facile operation and high efficiency [5], this technique will allow us to prepare the ZnO seed layers on the substrate to later fabricated the ZnO nanostructures.
On the other hand, ZnO has been limited by two challenging issues: the absorption only in the UV region of the solar spectrum and the high recombination rate [6,7]. At present, carbonaceous materials hybridized with semiconductors have attracted much attention; due to that it can effectively enhance the photocatalytic activity reduced the recombination [[8], [9], [10]]. Among the carbon family, graphene, two-dimensional (2D) carbon-based honeycomb lattice material (hexagonal atomic structure) [11], offers new opportunities in photocatalysis. Various studies demonstrate that reduced graphene oxide (RGO) can effectively increase the photocatalytic activity [[12], [13], [14]] because of its outstanding conductivity [15], superior chemical stability, extremely high theoretical specific surface area [16], suitable pore size distribution and good capacitor performance [17]. Furthermore, the hexagonal atomic structure of graphene is able to supply a building platform for the epitaxial growth of another hexagonal nanostructure such as ZnO [18].
Recent advances in ZnO/RGO nanoscale materials have focused on well-designed nanocomposites that are highly oriented and organized [19,20]. Therefore, in the present work, nanorods (NRs) from different amounts of RGO-loaded ZnO have been fabricated on FTO glass substrates via a novel electrospinning assisted hydrothermal method, with RGO sheets present in the ZnO-RGO seeds layers fabricated by electrospinning. Moreover, we demonstrate the influence of different amounts of RGO on the morphology, crystallinity, optical properties, and photocatalytic activity for methyl orange degradation of ZnO-RGO NRs fabricated. The ZnO-RGO NRs were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy and Photoluminescence (PL). Finally, the photocatalytic activity of the ZnO-RGO NRs toward the decomposition of methyl orange (MO) was investigated.
Section snippets
Experimental
The precursor solution used in electrospinning for the ZnO-RGO seeds formation was made by dissolving 1 g of zinc acetate dehydrate (Zn(CH3COO)2⋅H2O) and 1 g of polyvinylpyrrolidone in N-N dimethylformamide and stirring them until the solution became clear. Then, different amounts of commercial RGO (0.5 mL, 1.0 mL and 1.5 mL) were added to the precursor solution and stirred until the solution became dark. The resulting spinning solution was immediately transferred into a plastic syringe
Results and discussion
Fig. 1 shows the morphology obtained by scanning electron microscopy of ZnO-RGO seeds made by using spinning solutions with different amount of RGO (left side) and their respective ZnO-RGO NRs obtained after the hydrothermal growth (right side). The FE-SEM images for the seeds confirms anchoring and growth of the ZnO on the surface of RGO sheets (regions enclosed by discontinuous white lines). Moreover, it can be considered that there is a strong interaction between the ZnO nanoparticles and
Conclusions
In summary, ZnO-RGO NRs including different amounts of RGO were fabricated by hydrothermal growth onto ZnO-RGO seed layers fabricated by electrospinning technique. The adhered RGO sheets were found to play an important role in morphology, optical properties and photocatalytic activity of the ZnO-RGO NRs. The mean diameter of the ZnO-RGO NRs ranged from 34 to 50 nm. The photocatalytic activities for the photodegradation of methyl orange in aqueous solution were studied. The ZnO-RGO nanostructure
Acknowledgements
This work was supported by the Projects Nº 133-FINCYT-IB-2015 and Nº 113-INNOVATE PERU-ISASS-2018, P. R. would like to thank the Peruvian Council for Science and Technology (CONCYTEC) for the Scholarship.
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