1. Joint Center for Artificial Photosynthesis; California Institute of Technology; Pasadena CA 91125 USA
2. Division of Chemistry and Chemical Engineering; 210 Noyes Laboratory; 127-72, California Institute of Technology; Pasadena CA 91125 USA
3. Department of Applied Physics and Materials Science; California Institute of Technology; Pasadena CA 91125 USA
4. Beckman Institute and Molecular Materials Research Center; California Institute of Technology; Pasadena CA 91125 USA
5. Kavli Nanoscience Institute; California Institute of Technology; Pasadena CA 91125 USA