title: Water reduction by a p-GaInP2 photoelectrode stabilized by an amorphous TiO2 coating and a molecular cobalt catalyst.
abstract: Producing hydrogen through solar water splitting requires the coverage of large land areas. Abundant metal-based molecular catalysts offer scalability, but only if they match noble metal activities. We report on a highly active p-GaInP2 photocathode protected through a 35-nm TiO2 layer functionalized by a cobaloxime molecular catalyst (GaInP2-TiO2-cobaloxime). This photoelectrode mediates H2 production with a current density of ∼9 mA cm(-2) at a potential of 0 V versus RHE under 1-sun illumination at pH 13. The calculated turnover number for the catalyst during a 20-h period is 139,000, with an average turnover frequency of 1.9 s(-1). Bare GaInP2 shows a rapid current decay, whereas the GaInP2-TiO2-cobaloxime electrode shows ≤5% loss over 20 min, comparable to a GaInP2-TiO2-Pt catalyst particle-modified interface. The activity and corrosion resistance of the GaInP2-TiO2-cobaloxime photocathode in basic solution is made possible by an atomic layer-deposited TiO2 and an attached cobaloxime catalyst.
authors.affiliation: National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado 80401, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Gu
authors.affiliation: National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado 80401, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yan
authors.affiliation: National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado 80401, USA.|Material Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Young
authors.affiliation: National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado 80401, USA.
authors.forename: K Xerxes
authors.initials: KX
authors.lastname: Steirer
authors.affiliation: National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado 80401, USA.
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Neale
authors.affiliation: National Renewable Energy Laboratory, Chemistry and Nanoscience Center, Golden, Colorado 80401, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Turner