1. Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Staatsartillerie Rd, Pretoria West, Pretoria 0183, South Africa
2. Institute of Nano Engineering Research (INER), Tshwane University of Technology, Staatsartillerie Rd, Pretoria West, Pretoria 0183, South Africa
3. Department of Electrical Engineering, Tshwane University of Technology, Staatsartillerie Rd, Pretoria West, Pretoria 0183, South Africa
4. Ecole Superieure d’Ingenieurs en Electrotechnique et Electronique, 2 Boulevard Blaise Pascal, 93160 Noisy-Le-Grand, France