NANOPOSTER 2018 - 8th Virtual Nanotechnology Poster Conference
Registration no.: P18-09
TMDC based nanocomposite as efficient photocatalyst Sanni Kapatel* and C. K. Sumesh Department of Physical Sciences, P. D. Patel Institute of Applied Sciences (PDPIAS) Charotar University of Science and Technology, CHARUSAT Campus, Changa – 388 421, Gujarat, INDIA Email: *sannikapatel.phys@charusat.ac.in
ABSTRACT
INTRODUCTION
In this work, we report the creation of binary semiconductor nanocomposite (NC) comprising spherical ZnO nanoparticles stacked with two-dimensional (2D) MoS2 nanosheets, utilizing a facile microwave assisted synthesis technique. The fabricated product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy instrument (HR-TEM), Scanning electron microscopy (SEM), Raman spectroscopy (RS), Energy-dispersive X-ray spectroscopy (EDAX), Inductively coupled plasma (ICP) analysis and Fourier transform infrared spectroscopy (FTIR) to distinguish the structure and morphology of arranged NC. Ultraviolet-Visible (UV-Vis) spectroscopy was used to understand the optical properties of MoS2.ZnO NC. Optical transmission spectra gave a distinct red shift in the band gap of ZnO after making composition with MoS2 nanosheets which eventually shows higher retention of visible light. This occurs due to effective separation of photogenerated charge carriers and rapid charge transfer to reactions sites of conduction band potentials of both ZnO and MoS2 both. We plot that MoS2.ZnO NC has a band gap of 2.73 eV which is fundamentally a long way from the band gap of ZnO (~3.3eV). The outcomes recommended the effective fading out of methylene blue (MB) (more than 95%) in 1 hour on the illumination of visible light. Besides, the association of MoS2 prevents photo-corrosion of the ZnO bringing about upgraded photostability of the catalyst during the reaction. Moreover, we presented a recyclability test of the photocatalyst for five subsequent times to get the efficient dye degradation. A straightforward, easy and powerful technique to build up binary NC (heterostructure) that add to the change of visible light determined photocatalytic execution is proposed.
In this report, we strategized to grow MoS2.ZnO NC using hybrid method to understand it’s suitability as a photocatalyst. We proposed two-step microwave assisted method to fabricate MoS2.ZnO, resulted with very good crystalline phase of NC confirmed by XRD and Raman spectroscopy. We used prepared composition to confirm efficient degradation of MB under illumination of visible light. The fundamental advantage that we reported here is the NC helps to minimize the rate of recombination and photogenerated charge carriers to give effective dye degradation. Moreover, we stressed upon the reusability of the photocatalyst for multiple times and interestingly it delivers same results of dye degradation for five consecutive recycles unlike other co-catalyst based mechanisms. Recently, there are many research articles came which proposes efficient photocatalyst for dye degradation based on transition metal chalcogenides combined with ZnO, especially with MoS2.ZnO nanocomposite [1-4]. There are multiple articles where they use various method to synthesize MoS2.ZnO NC and used it for photocatalysis, H2 evolution and other gas sensors [5]. Hence, we prepared a hybrid nanostructure which shows enhanced phototcatalytic activity under visible light irradiation. The efficient performance over pristine MoS2 flakes and bare ZnO NPs the composite synergistically showed superior rate of separation of photo-generated charge carriers. We report easy, cost effective and low temperature method to produce MoS2.ZnO NC and to employ it for water treatments and environmental applications.
MATERIALS & METHODS
RESULTS X-ray Diffractograph
RAMAN Spectroscopy
As prepared MoS2 and ZnO was found hexagonally structured, reference taken of both from JCPDC card no. 73-108 and 891397 and so as the prepared MoS2.ZnO nanocomposite. Average crystallite size had been obtained using Debey-Scherrer formula from fullwidth half maximum (FWHM) of the reflection peaks MoS2 (002), ZnO (100) and MoS2.ZnO (100) encountered to be 8.9 nm, 22.4 nm and 13.3 nm respectively. MoS2 presence of wavenumbers 381 cm-1 (E12g) and 409 cm-1 (A1g); For ZnO 331 cm-1 (E2H-E2L), 381 cm-1 (A1T) and 436 cm-1 (E2) modes; Peak 331 cm-1 confirms the merger of two vibrational modes E12g and A1T
Transmission electron microscopy As-prepared MoS2.ZnO nanocomposite was ground before TEM analysis which shows uniform shaped spherical particles with average size of 8 nm as shown in the 1st TEM image. It is also clear form the same figure there is proper composition of the MoS2 laminas and ZnO NPs occurred which is further inferred by taking High-resolution TEM image. It is further deduced form HRETM image that the presented results of XRD are well-matched.
Hydrothermal approach has been used to prepare MoS2 nanoflakes where Ammonium Molybdate ((NH4)6Mo7O24) and Thiourea (CH4N2S) in 1:2 proportion was dissolved into the 100 ml distilled water under continuous stirring of 0.5 hours to form a uniform mixture, and then the solution is transferred into a 200 ml Teflon-lined stainless steel autoclave and maintained at 190 ºC for 24 hours. 0.6mM aqueous solutions of zinc nitrate-di-hydrate (Zn (CH3COO).2H2O) in 100 ml of distilled water, Ammonia solution (NH4OH) was added dropwise to achieve 10 pH then the equivalent amount of prepared MoS2 powder was added and stirred to form a homogeneous suspension then irradiated in a microwave oven for 15 min set at 150 W. Finally, product was filtered and washed with distilled water and methanol until it became free from excess residues. Eventually, the sample was dried at 150 °C for 5 hours
CONCLUSION
Photocatalysis using MoS2.ZnO NC
• To summarize, we have reported a facile In-situ preparation of MoS2.ZnO binary nanocomposite to form a visible light active photocatalyst. The microwave-assisted environment-friendly method enables to synthesize spherically shaped MoS2.ZnO nanocomposites. • There is an ideal nanocomposite formulation took the place of MoS2 and ZnO which ultimately improves the photodegradation rate. The synergetic effect of MoS2.ZnO catalyst dosage has been found to provide more reaction sites due to the high surface area of constituent compounds, increased absorption in visible light and prevents ZnO from photo-corrosion by rapid interfacial charge transfer across the MoS2.ZnO heterojunction. • The nanocomposite was found to have stronger light absorption in the visible light region due to the achievement of the tunable band gap. The prepared nanocomposite shows excellent activity towards the photocatalytic degradation of MB dye under visible light irradiation with an optimal catalyst load of 1g/l and a degradation rate >95% in one hour as compared to the bare ZnO, MoS2, and other reported semiconductors.
REFERENCES [1] S. Kumar et al., ChemSusChem, vol. 10, no. 18, pp. 3588–3603, 2017.
[4] S. Zhang, F. Tang et al., Radiat. Phys. Chem., vol. 137, pp. 104–107, 2017.
[2] S. E. Islam et al., Chem. - A Eur. J., vol. 24, no. 37, pp. 9305–9315, 2018.
[5] Q. Tian et al., Nanoscale Res. Lett., vol. 12, no. 1, 2017
[3] Y. H. Tan et al., J. Appl. Phys., vol. 116, no. 6, 2014.
ACKNOWLEDGMENT: The authors are grateful to the support of Charotar University of Science and Technology (CHARUSAT), Changa
Pictorial diagram of MB dye degradation
Preparation of ZnO loaded MoS2 with microwave route over where MoS2 was prepared using hydrothermal route The faster and efficient catalyst for MB dye degradation which can be applied to other textile dye as well More than 90% dye degradation within one hour Most important aspect on we focus is recyclability of the catalyst for three time without giving any treatment