1. Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, 01510 Vitoria-Gasteiz, Spain
2. Department of Applied Physics II, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Barrio Sarriena, s/n, 48940 Leioa, Spain
3. Umicore, 31 rue du Marais, 1000 Brussels, Belgium
4. Ikerbasque, The Basque Foundation for Science, 48013 Bilbao, Spain