1. STUDIES ON PHOTOCATALYTIC ACTIVITY OF NANOCOMPOSITES OF NITROGEN DOPED GRAPHENE WITH METAL MOLYBDATES (NG-MMoO4)
Manesh Kumar and H. N. Sheikh*
Department of Chemistry, University of Jammu, Jammu , India
Abstract
Nitrogen doped graphene based materials have been widely used as transparent conducting electrodes, supercapacitors, optoelectronic devices, composites, and catalysts. Well defined nanocomposites of nitrogen doped graphene with metal molybdates were synthesized via facile hydrothermal method. The X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the structural properties of prepared nanocomposites. The photocatalytic activity of prepared nanocomposites was investigated by using UV-Visible Spectroscopy. The presence of nitrogen doped graphene enhances the photocatalytic activity of the parent metal molybdates. The nitrogen doped graphene based nanocomposites facilitated the photodegradation rate of methylene blue. The morphological features of as synthesized nanocomposites were studied by SEM analysis. TEM images show that average crystallite size of prepared nanocomposites ranges from nm. The natures of presence of functional groups were confirmed by using FT-IR spectroscopy.
Fig. 1 PXRD of (a) NG (b) MnMoO4 (c) NG-MnMoO4 (d) CoMoO4 (e ) NG-CoMoO4 (e) NiMoO4 (f)NG-NiMoO4
Fig. 2 FT-IR Spectra of (a) NG (b) MnMoO4 (c) NG-MnMoO4
(d) CoMoO4 (e) NG-CoMoO4 (e) NiMoO4 (f) NG-NiMoO4
Scheme 1. Synthesis of GO, NG, MMoO4 & NG-MMoO4
Fig. 3 Photodegradation of MB as function of time
Fig. 4 Kinetics of photodegradation
Fig. 5 Mechanism of photodegradation
Conclusion
In summary, we have demonstrated hydrothermal method for the synthesis of nanocomposites of nitrogen doped graphene with metal molybdates (NG-MMoO4) and MMoO4 (M = Mn, Co and Ni). The prepare nanocomposites were characterized by PXRD, SEM, TEM, FT-IR and TGA studies. The crystallite size of the nanostructures calculated from PXRD and TEM analysis was found in the range of nm. SEM and TEM images reveal that the MMoO4 nanoparticles are evenly decorated on nitrogen doped graphene (NG) sheets. The photocatalytic activity of the prepared nanocomposites was demonstrated by studying the photodegradation of methylene blue (MB). The electronic Spectra of methylene blue in presence of NG-MnMoO4 suggested enhanced photocatalytic activity. The kinetic studies of photodegradation of methylene blue in presence of bare MnMoO4 and its nanocomposite with nitrogen doped graphene suggested that nitrogen doped graphene nanocomposites are better photocatalyst than corresponding bare metal molybdates. TGA suggested the thermal stabilities of the bare MMoO4 are higher than that of NG-MMoO4 nanocomposites.
Fig. 7 TEM images
Fig. 6 SEM images