Microwave-Assisted Synthesis of rGO-ZnO/CuO Nanocomposites for Photocatalytic Degradation of Organic Pollutants

Abstract

Nanomaterial-based catalytic conversion of hazardous organic pollutants into benign substances is one of the green methods employed for wastewater treatment. This study demonstrates the fabrication of (rGO-ZnO)/CuO nanocomposites (NCs) via a microwave (MW)-assisted method for (photo)catalytic application. The crystal structure, optical, morphological, and electrochemical characteristics were examined using X-ray diffraction (XRD), spectroscopic, microscopic, and electrochemical techniques. The analysis indicated that rod-like (rGO-ZnO)/CuO NCs having a nanoscale diameter with enhanced light absorption and well-matched band positions between rGO-ZnO and CuO were formed. Furthermore, the catalytic reduction of 4-nitrophenol (4-NP) and photocatalytic degradation of methylene blue (MB) tests showed remarkable results with rate constants of 0.468 min−1 for 4-NP reduction within 8 min and 0.02213 min−1 for MB degradation within 105 min. Thus, the artful decoration of ZnO nanorods (NRs) with CuO into the (rGO-ZnO)/CuO NCs interface is an effective strategy for fabricating highly efficient photocatalysts.

Synthesis of Ag @CuO nanocomposites supported by reduced graphene oxide nanosheets: harnessing photocatalytic degradation of naphthol blue black dye

“…From Figure 2c–e, as it can be seen in the spectrum of the Ag–CuO/GO composite (Ag 1%, 5%, and 10%) that the peak at 628 cm −1 is attributed to vibrations associated with the CuO bond during stretching. Furthermore, it can be observed that the addition of Ag with various ratios, that is, 1%, 5%, and 10%, significantly reduced the stretching intensity of OH and increased the peak transmittance of the composite, confirming higher light absorption due to surface plasmon resonance 36–38 …”

“…These figures show that at some locations rGO and CuO with Ag were mixed properly and form sheets of composites with fibrillary structures that were tightly stacked while at other locations they were arranged haphazardly, which may result from the breakage or exfoliation of larger sheets. Overall, the SEM images show that all three components were mixed efficiently, which enhance the performance activity of catalyst 38,44–48 …”

“…Overall, the SEM images show that all three components were mixed efficiently, which enhance the performance activity of catalyst. 38,[44][45][46][47][48] The Raman spectroscopy is a useful technique for determining the properties of materials. Figure 5 illustrates the Raman spectra of CuO, wherein hybrid composite contains rGO and CuO NPs and Ag-CuO/rGO nanocomposite.…”

“…Furthermore, it can be observed that the addition of Ag with various ratios, that is, 1%, 5%, and 10%, significantly reduced the stretching intensity of OH and increased the peak transmittance of the composite, confirming higher light absorption due to surface plasmon resonance. [36][37][38] Figure 3 illustrates the XRD analysis of the copper oxide (CuO), CuO/rGO, and Ag-CuO/rGO with the various ratios of Ag (Ag 1%, 5%, and 10%) nanocomposites. In Figure 3b can be ascribed to the (110), (002), ( 111), (À202), ( 202), (À113), (À311), and (220) facets of the crystalline CuO phase, respectively.…”

Effectual visible light photocatalytic reduction of para-nitro phenol using reduced graphene oxide and ZnO composite

“…Multiple studies have been reported on ZnO combinational catalysts such as NiS/ZnO 23 , CuO/ZnO 24 , Ni/rGO 25 , Ag/ZnO 26 – 28 , ZnO 29 , graphene-ZnO 30 , 31 , Co–ZnO 32 for the PNP reduction reaction. Recently, Bekru et al, reported the (rGO–ZnO)/CuO nanocomposite interface is a highly efficient photo-catalyst for PNP reduction 33 . Reduced graphene oxide and semiconductor based composite exhibit increased photocatalytic performance than pure oxide nanostructure 34 .…”