1. Institute of NanoEngineering Research (INER), Department of Chemical, Metallurgical and Materials Engineering, Faculty of Engineering and the Built Environment, Tshwane University of Technology, Pretoria 0183, South Africa
2. Centre for Nanostructures and Advanced Materials, DSI-CSIR Nanotechnology Innovation Centre, Council for Scientific and Industrial Research, CSIR, Pretoria 0001, South Africa
3. Department of Chemical Sciences, University of Johannesburg, Doornforntein, Johannesburg 2028, South Africa
4. French South African Institute of Technology (F’SATI)/Department of Electrical Engineering, Tshwane University of Technology, Pretoria 0001, South Africa
5. École Supérieure d’Ingénieurs en Électrotechnique et Électronique, Cité Descartes, 2 Boulevard Blaise Pascal, Noisy-le-Grand, 93160 Paris, France