1. Department of Chemistry Faculty of Science University of Douala, P.O. Box 24 157 Douala Cameroon
2. Laboratory of Analytical Chemistry Faculty of Science University of Yaoundé 1, P.O. Box 812 Yaoundé Cameroon
3. Department of Chemistry and Center for Catalysis Research and Innovation University of Ottawa 10 Marie Curie K1 N6 N5 Ottawa Ontario Canada
4. Electrochemistry and Chemistry of Materials Department of Chemistry Faculty of Science University of Dschang PO Box 67 Dschang Cameroon