title: Enabling Overall Water Splitting on Photocatalysts by CO-Covered Noble Metal Co-catalysts.
abstract: Photocatalytic overall water splitting requires co-catalysts that efficiently promote the generation of H2but do not catalyze its reverse oxidation. We demonstrate that CO chemisorbed on metal co-catalysts (Rh, Pt, Pd) suppresses the back reaction while maintaining the rate of H2evolution. On Rh/GaN:ZnO, the highest H2production rates were obtained with 4-40 mbar of CO, the back reaction remaining suppressed below 7 mbar of O2. The O2and H2evolution rates compete with CO oxidation and the back reaction. The rates of all reactions increased with increasing photon absorption. However, due to different dependencies on the rate of charge carrier generation, the selectivities for O2and H2formation increased in comparison to CO oxidation and the back reaction with increasing photon flux and/or quantum efficiency. Under optimum conditions, the impact of CO to prevent the back reaction is identical to that of a Cr2O3layer covering the active metal particle.
authors.affiliation: Department of Chemistry and Catalysis Research Center, TU München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Tobias F
authors.initials: TF
authors.lastname: Berto
authors.affiliation: Department of Chemistry and Catalysis Research Center, TU München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Kai E
authors.initials: KE
authors.lastname: Sanwald
authors.affiliation: Department of Materials Science and Engineering, University of California , Davis, California 95616, United States.
authors.forename: J Paige
authors.initials: JP
authors.lastname: Byers
authors.forename: Nigel D
authors.initials: ND
authors.lastname: Browning
authors.affiliation: Department of Chemistry and Catalysis Research Center, TU München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Oliver Y
authors.initials: OY
authors.lastname: Gutiérrez
authors.affiliation: Department of Chemistry and Catalysis Research Center, TU München , Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Lercher