SrNbO2N as a water-splitting photoanode with a wide visible-light absorption band

Kazuhiko Maeda, Masanobu Higashi, Bhavin Siritanaratkul, Ryu Abe, Kazunari Domen

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Strontium niobium oxynitride (SrNbO2N) 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 2SO4, pH ≈ 6). SrNbO2N, 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 H2 and O2 evolution was achieved using a SrNbO2N/FTO electrode modified with colloidal iridium oxide (IrO2) 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.

Original languageEnglish
Pages (from-to)12334-12337
Number of pages4
JournalJournal of the American Chemical Society
Issue number32
Publication statusPublished - 17 Aug 2011
Externally publishedYes

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