1. Thomas J. Watson Laboratory of Applied Physics and Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, California 91125 United States
2. Laboratory of Nanoscience for Energy Technologies (LNET), EPFL, 1015 Lausanne, Switzerland
3. Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States