title: Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure.
abstract: Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilizes customized tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalization procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Solar Fuels, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.|Department of Physcis, Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 5, D-98693 Ilmenau, Germany.|Department of Physcis, Humboldt-Universität zu Berlin, Newtonstraße 15, D-12489 Berlin, Germany.
authors.forename: Matthias M
authors.identifier: http://orcid.org/0000-0002-1252-806X
authors.initials: MM
authors.lastname: May
authors.affiliation: California Institute of Technology, Joint Center for Artificial Photosynthesis, 1200 East California Boulevard, Pasadena, California 91125, USA.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Lewerenz
authors.affiliation: Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, D-79110 Freiburg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Lackner
authors.affiliation: Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, D-79110 Freiburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Dimroth
authors.affiliation: Department of Physcis, Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 5, D-98693 Ilmenau, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hannappel