1. Department of Chemistry, Durban University of Technology, Durban 4000, South Africa
2. DST/Mintek NIC, Advanced Materials Division, Mintek, 200 Malibongwe Drive, Randburg 2125, South Africa
3. Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie-Curie Pvt, STEM Complex, Room 342, Ottawa, ON K1N 6N6, Canada