title: SrNbO2N as a water-splitting photoanode with a wide visible-light absorption band.
abstract: Strontium niobium oxynitride (SrNbO(2)N) particles were coated on fluorine-doped tin oxide (FTO) glass and examined as a photoelectrode for water splitting under visible light in a neutral aqueous solution (Na(2)SO(4), pH ≈ 6). SrNbO(2)N, which has a band gap of ca. 1.8 eV, acted as an n-type semiconductor and generated an anodic photocurrent assignable to water oxidation upon irradiation with visible-light photons with wavelengths of up to 700 nm, even without an externally applied potential. Under visible light (λ > 420 nm) with an applied potential of +1.0-1.55 V vs RHE, nearly stoichiometric H(2) and O(2) evolution was achieved using a SrNbO(2)N/FTO electrode modified with colloidal iridium oxide (IrO(2)) as a water oxidation promoter. This study presents the first example of photoelectrochemical water splitting involving an n-type semiconductor with a band gap smaller than 2.0 eV that does not require an externally applied potential.
authors.affiliation: Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Maeda
authors.forename: Masanobu
authors.initials: M
authors.lastname: Higashi
authors.forename: Bhavin
authors.initials: B
authors.lastname: Siritanaratkul
authors.forename: Ryu
authors.initials: R
authors.lastname: Abe
authors.forename: Kazunari
authors.initials: K
authors.lastname: Domen