Grape seed extract assisted synthesis of dual-functional anatase TiO₂ decorated reduced graphene oxide composite for supercapacitor electrode material and visible light photocatalytic degradation of bromophenol blue dye

The grape extract is a potential natural reducing agent because of its high phenolic content. The extracts of seeds, skin, and pulp of grape were prepared by digestion, grinding, and soxhlet methods and used for reducing graphene oxide (GO). The reduced GO made using the soxhlet extract of grape seed (GRGO) was hydrothermally treated with titanium dioxide (TiO2) for the synthesis of GRGO-TiO2 nanocomposite. The X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-vis, photoluminescence, and Raman spectra studies further confirmed the formation of GRGO and the GRGO-TiO2 hybrid. Scanning electron microscope and transmission electron microscope studies showed the decoration of spherical TiO2 particles ( 400 nm), GRGO-TiO2 showed ∼30% higher photo-oxidation of the bromophenol blue (BPB) dye than TiO2. Also, GRGO-TiO2 decreased the total organic carbon content of BPB from 92 to 18 ppm. Overall, the soxhlet extract of grape seed was found to be a cost-effective reducing agent for the preparation of GRGO, which is a suitable material to be used in supercapacitors and photocatalysis.Published versionThe authors are grateful to the Department of Science and Technology, Government of India, for its financial support. S. Ramasundaram and B. Kim acknowledge the Korea Ministry of Education, Science, and Technology for its financial support via the National Research Foundation of Korea for the priority Research Centers Program (NRF-2018R1A6A1A03025526) and in part by the Sabbatical Research Promotion Funding from the Korea University of Technology and Education

Effective Attenuation of Electromagnetic Waves by Synergetic Effect of α-Fe2O3 and MWCNT/Graphene in LDPE-Based Composites for EMI Applications

In this study, a polymer nanocomposite is synthesized using magnetic and conducting fillers for enhanced electromagnetic interference (EMI) shielding. Alfa-ferrite (α-Fe2O3) nanoparticles with minimal multiwalled carbon nanotube (MWCNT) as low as 5 weight % in combination with variable concentrations of graphene nanoplatelets (GNP) are used as fillers in low-density polyethylene (LDPE) polymer matrix. Nanofillers and the polymer matrix are characterized by various techniques such as XRD, SEM, color mapping, EDAX, TGA, etc. The EMI shielding efficiency of the LDPE-based nanocomposites is tested using Vector Network Analyzer (VNA). The results showed that composite with LDPE:MWCNT:GNP:α-FO-50:5:40:5 displayed enhanced EMI shielding (in X-band (8.2–12.4 GHz) compared to other concentrations studied. This is due to the superior ohmic, dielectric, and magnetic losses at this particular composition and to the synergism amongst the filler. An attenuation of 99.99% was achieved for 5% α-Fe2O3. The mechanistic aspects of the shielding are discussed using permittivity, conductivity, and attenuation