1. HySA Infrastructure Centre of Competence, Energy Centre, Council for Scientific and Industrial Research (CSIR), PO Box 395, Pretoria 0001, South Africa
2. Faculty of Natural Science, University of the Western Cape, Bellville, Cape Town 7535, South Africa
3. Department of Chemistry, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
4. School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom