1. Laboratory of Nanochemistry for Energy Research, Institute of Chemical Sciences and Engineering, Ecole Politechnique Fédérale de Lausanne, Sion CH-1950, Switzerland
2. Institute of Chemical Sciences and Engineering, Ecole Politechnique Fédérale de Lausanne, Sion CH-1950, Switzerland
3. National Renewable Energy Laboratory (NREL), Golden, Colorado 80401, United States