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The Effects of Preparation Conditions for a BaNbO 2 N Photocatalyst on Its Physical Properties
Author(s) -
Hisatomi Takashi,
Katayama Chisato,
Teramura Kentaro,
Takata Tsuyoshi,
Moriya Yosuke,
Minegishi Tsutomu,
Katayama Masao,
Nishiyama Hiroshi,
Yamada Taro,
Domen Kazunari
Publication year - 2014
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.201400121
Subject(s) - niobium , photocatalysis , barium , ammonia , inorganic chemistry , dissociation (chemistry) , ion , materials science , catalysis , ammonia production , chemistry , organic chemistry , metallurgy
Abstract BaNbO 2 N is a semiconductor photocatalyst active for water oxidation under visible‐light irradiation up to λ =740 nm. It is important to understand the nitridation processes of precursor materials to form BaNbO 2 N to tune the physical properties and improve the photocatalytic activity. Comprehensive experiments and analyses of temperatures, durations, ammonia flow rates, and barium/niobium ratios in the precursor during the nitridation process reveals that faster ammonia flow rates and higher barium/niobium ratios in the precursors help to suppress reduction of pentavalent niobium ions in the nitridation products and that the use of a precursor prepared by a soft‐chemistry route allows the production of BaNbO 2 N at lower temperatures in shorter times than the use of physical mixtures of BaCO 3 and Nb 2 O 5 because the niobium species is dispersed among the barium species. BaNbO 2 N prepared by the soft‐chemistry route exhibits comparatively higher activity than that prepared from physical mixtures of BaCO 3 and Nb 2 O 5 , probably because of lower nitridation temperatures, which suppress excessive dissociation of ammonia, and thereby reduce pentavalent niobium ions, and intimate interaction of niobium and barium sources, which lowers the densities of mid‐gap states associated with defects.