1. Department of Chemistry, Vaal University of Technology, Vanderbijlpark, South Africa
2. Department of Physics, University of Western Cape, Bellville, South Africa
3. MRG Nanoscience Laboratories, iThemba Labs, Somerset West, South Africa
4. Group of Polymers and Nanomaterials, Laboratory of Solid State Physics, Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah, University Fez, Morocco