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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >The contrasting effect of the Ta/Nb ratio in (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 crystals on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives
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The contrasting effect of the Ta/Nb ratio in (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 crystals on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives

机译：（111）层B位置缺陷六方钙钛矿Ba5Nb4-xTaxO15晶体中Ta / Nb比对其氧氮化物衍生物在可见光诱导的光催化水氧化活性中的对比作用

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The effect of the Ta/Nb ratio in the (111)-layered B-site deficient hexagonal perovskite Ba5Nb4-xTaxO15 (0 <= x <= 4) crystals grown by a KCl flux method on visible-light-induced photocatalytic water oxidation activity of their oxynitride derivatives BaNb1-xTaxO2N (0 <= x <= 1) was investigated. The Rietveld refinement of X-ray data revealed that all Ba5Nb4-xTaxO15 samples were well crystallized in the space group P (3) over bar m1 (no. 164). Phase-pure BaNb1-xTaxO2N (0 <= x <= 1) porous structures were obtained by nitridation of the flux-grown oxide crystals at 950 degrees C for 20, 25, 30, 35, and 40 h, respectively. The absorption edge of BaNb1-xTaxO2N (0 <= x <= 1) was slightly shifted from 720 to 690 nm with the increasing Ta/Nb ratio. The O-2 evolution rate gradually progressed and reached the highest value (127.24 mu mol in the first 2 h) with the Ta content up to 50 mol% but decreased at 75 and 100 mol% presumably due to the reduced specific surface area and high density of structural defects, such as grain boundaries acting as recombination centers, originated from high-temperature nitridation for prolonged periods. Transient absorption spectroscopy provided evidence for the effect of the Ta/Nb ratio on the behavior and energy states of photogenerated charge carriers, indicating a direct correlation with photocatalytic water oxidation activity of BaNb1-xTaxO2N.
机译：KCl通量法生长的（111）层B位置缺陷的六方钙钛矿型Ba5Nb4-xTaxO15（0 <= x <= 4）晶体中Ta / Nb比对可见光诱导的光催化水氧化活性的影响研究了它们的氧氮化物衍生物BaNb1-xTaxO2N（0 <= x <= 1）。 X射线数据的Rietveld精炼显示，所有Ba5Nb4-xTaxO15样品均在bar m1（编号164）上方的空间群P（3）中充分结晶。通过在950摄氏度下对助焊剂生长的氧化物晶体分别进行20、25、30、35和40 h的氮化，可以获得纯相BaNb1-xTaxO2N（0 <= x <= 1）多孔结构。随着Ta / Nb比的增加，BaNb1-xTaxO2N（0 <= x <= 1）的吸收边从720 nm稍微移至690 nm。 O-2的析出速率逐渐提高并达到最高值（前2 h为127.24μmol），Ta含量高达50 mol％，但由于比表面积减小和比表面积高而降低到75和100 mol％。结构缺陷的密度，例如充当复合中心的晶界，是由长时间的高温氮化引起的。瞬态吸收光谱法提供了Ta / Nb比对光生电荷载流子的行为和能态的影响的证据，表明其与BaNb1-xTaxO2N的光催化水氧化活性直接相关。

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