1. Department of Chemical Engineering, University of South Africa (UNISA), Christiaan De Wet & Pioneer Avenue, Florida, 1710, South Africa
2. Laboratory of Material Chemistry, Department of Inorganic Chemistry, University of Yaoundé I (UYI), P. O. Box 812, Yaoundé, Cameroon
3. Laboratory of Solid State and Molecular Inorganic Chemistry, Department of Chemistry, University of Dschang, Cameroon
4. College of Science, Engineering and Technology (CSET), University of South Africa, Florida Campus, Johannesburg 1710, South Africa
5. Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710, South Africa