a
Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley, USA
E-mail: azweber@lbl.gov
b
Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
E-mail: sophia.haussener@epfl.ch
c
Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, USA
E-mail: nslewis@caltech.edu
d
Beckman Institute and Kavli Nanoscience Institute, 1200 E. California Blvd., California Institute of Technology, Pasadena, USA