1. Department of Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium, Department of Metallurgy, Electrochemistry and Materials Science, Vrije Universiteit Brussel (VUB), 1050 Brussel, Belgium, and Agfa-Gevaert N.V., Septestraat 27, 2640 Mortsel, Belgium