title: Efficient suppression of back electron/hole recombination in cobalt phosphate surface-modified undoped bismuth vanadate photoanodes.
abstract: In this paper, we compared for the first time the dynamics of photogenerated holes in BiVO4photoanodes with and without CoPi surface modification, employing transient absorption and photocurrent measurements on microsecond to second timescales. CoPi surface modification is known to cathodically shift the water oxidation onset potential; however, the reason for this improvement has not until now been fully understood. The transient absorption and photocurrent data were analyzed using a simple kinetic model, which allows quantification of the competition between electron/hole recombination and water oxidation. The results of this model are shown to be in excellent agreement with the measured photocurrent data. We demonstrate that the origin of the improvement of photocurrent onset resulting from CoPi treatment is primarily due to retardation of back electron/hole recombination across the space charge layer; no evidence of catalytic water oxidationviaCoPi was observed.
authors.affiliation: Department of Chemistry , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK . Email: j.durrant@imperial.ac.uk.
authors.forename: Yimeng
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Chemistry , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK . Email: j.durrant@imperial.ac.uk; Laboratory for Molecular Engineering of Optoelectronic Nanomaterials , Institute of Chemical Sciences and Engineering , École Polytechnique Fédérale de Lausanne (EPFL) , Station 6 , CH H4 565 , Lausanne 1015 , Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Le Formal
authors.affiliation: Department of Chemistry , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK . Email: j.durrant@imperial.ac.uk.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kafizas
authors.affiliation: Department of Chemistry , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK . Email: j.durrant@imperial.ac.uk.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Pendlebury
authors.affiliation: Department of Chemistry , Imperial College London , South Kensington Campus , London , SW7 2AZ , UK . Email: j.durrant@imperial.ac.uk.
authors.forename: James R
authors.initials: JR
authors.lastname: Durrant