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Synthesis and Photocatalytic Activity of Perovskite Niobium Oxynitrides with Wide Visible‐Light Absorption Bands
Author(s) -
Siritanaratkul Bhavin,
Maeda Kazuhiko,
Hisatomi Takashi,
Domen Kazunari
Publication year - 2011
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201000207
Subject(s) - photocatalysis , niobium , niobium oxide , visible spectrum , materials science , perovskite (structure) , photochemistry , absorption (acoustics) , inorganic chemistry , aqueous solution , oxide , chemistry , catalysis , crystallography , organic chemistry , optoelectronics , metallurgy , composite material
Photocatalytic activities of perovskite‐type niobium oxynitrides (CaNbO 2 N, SrNbO 2 N, BaNbO 2 N, and LaNbON 2 ) were examined for hydrogen and oxygen evolution from water under visible‐light irradiation. These niobium oxynitrides were prepared by heating the corresponding oxide precursors, which were synthesized using the polymerized complex method, for 15 h under a flow of ammonia. They possess visible‐light absorption bands between 600–750 nm, depending on the A‐site cations in the structures. The oxynitride CaNbO 2 N, was found to be active for hydrogen and oxygen evolution from methanol and aqueous AgNO 3 , respectively, even under irradiation by light at long wavelengths ( λ <560 nm). The nitridation temperature dependence of CaNbO 2 N was investigated and 1023 K was found to be the optimal temperature. At lower temperatures, the oxynitride phase is not adequately produced, whereas higher temperatures produce more reduced niobium species (e. g., Nb 3+ and Nb 4+ ), which can act as electron‐hole recombination centers, resulting in a decrease in activity.