Photoanodes for water oxidation with visible light based on a pentacyclic quinoid organic dye enabling proton-coupled electron transfer
Giulia Alice Volpato, Martina Marasi, Thomas Gobbato, Francesca Valentini, Federica Sabuzi, Valeria Gagliardi, Alessandro Bonetto, Antonio Marcomini, Serena Berardi, Valeria Conte, Marcella Bonchio, Stefano Caramori, Pierluca Galloni, Andrea Sartorel
Abstract
A pentacyclic quinoid dye, KuQ(O)3OH, combining (i) extended visible absorption up to 600 nm, (ii) excited state reduction potential >2 V vs. NHE, and (iii) a photoinduced proton-coupled electron transfer mechanism, has been used for the fabrication of dye-sensitized SnO2 photoanodes integrating a ruthenium polyoxometalate water oxidation catalyst. The resulting photoelectrode SnO2|KuQ(O)3OH|Ru4POM displays a light harvesting efficiency up to 90% in the range 500-600 nm, an onset potential as low as 0.2 V vs. NHE at pH 5.8, photoinduced oxygen evolution with a faradaic efficiency of 70 ± 15% and an absorbed-photon-to-current efficiency up to 0.12 ± 0.01%.