Physical properties and enhanced photocatalytic activity of ZnO-rGO nanocomposites
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Physical properties and enhanced photocatalytic activity of ZnO‑rGO nanocomposites Poornima Sengunthar1 · K. H. Bhavsar1 · C. Balasubramanian2 · U. S. Joshi1 Received: 20 March 2020 / Accepted: 22 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Both zinc oxide (ZnO) and reduced graphene oxide (rGO) are known for its attractive optical properties in their nano form. Here, ZnO-rGO nanocomposites and rGO were prepared via simple and reproducible hydrothermal as well as modified Hummer’s method. Microstructural identification of phase formation and dispersion of ZnO on rGO was confirmed by X-ray diffraction and transmission electron microscopy (TEM) measurements. The reduction of graphene oxide was confirmed by the appearance of D and G band peaks in Raman spectra. Optical bandgap of samples was estimated by UV–Visible diffused reflectance spectroscopy up to IR region. A systematic study of photocatalytic behavior towards the degradation of organic dyes such as methyl orange and rhodamine B under the influence of UV light source is demonstrated. Better than 85% of degradation was measured for both the dyes in the presence of ZnO-rGO composite during 2 h of UV illuminations. The enhanced photocatalytic activity of the composites is attributed to electron–hole charge transfer, which also promises its use in photovoltaics. Keywords Reduced graphene Oxide(rGO) · ZnO-rGO nanocomposites · Photocatalytic activity
1 Introduction Wastewater treatment has gained much attention due to widespread pollution and rapid global climate changes. A variety of methods has been employed to treat polluted water such as filtration, adsorption and incineration, and photocatalysis. Amongst all, photocatalytic activity has been proved to be efficient and environmentally friendly in removing pollutants from wastewater using light irradiation [1]. In the photocatalytic activity, under UV light irradiation, e− are excited from the valence band to conduction band and form e −—hole pair that are responsible for the degradation of pollutants using semiconducting material as a catalyst. The quick recombination of photogenerated e−-hole pair results in quantum efficiency. A variety of electron–hole pair combination material have been widely studied such
* U. S. Joshi [email protected]; [email protected] 1
Department of Physics, School of Sciences, Gujarat University, Ahmedabad 380009, India
Atmospheric Plasma Division, F.C.I.P.T Campus, Institute for Plasma Research, Gandhinagar 382044, India
2
as, semiconductor-nobel metal composite, carbon nanotube (CNTs), Graphene-semiconductor composite and so on [2]. A single layer of carbon known as Graphene(sp2 bonded carbon atom arranged in hexagonal lattice) is a new material with a specific surface area of 2620 m2/g, intrinsic strength of 130GPa and 0 eV bandgap has received much attention [3, 4]. On the other side, synthesis of graphene oxide(GO), and reduced graphene oxide(rGO) has stimulated interest because of different properties compared to graphite
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