Effects of La doping on structural, optical, electronic properties of Sr2Bi2O5 photocatalyst
Effects of La doping on structural, optical, electronic properties of Sr2Bi2O5 photocatalyst
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DOI：
10.1016/j.jallcom.2015.10.199
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发表时间：
2016-02
影响因子：
6.2
通讯作者：
Y. Obukuro;S. Matsushima;K. Obata;Takuya Suzuki;M. Arai;E. Asato;Yuji Okuyama;N. Matsunaga;G. Sakai
中科院分区：
文献类型：
--
作者：
Y. Obukuro;S. Matsushima;K. Obata;Takuya Suzuki;M. Arai;E. Asato;Yuji Okuyama;N. Matsunaga;G. Sakai
以Sr[Bi（DTPA）]·9 H2O（DTPA为二乙烯三胺五乙酸）为前驱体，在700 °C下煅烧6 h，得到单相Sr 2Bi 2 O 5。研究了La掺杂对Sr[Bi（DTPA）]·9 H2O制备的Sr 2Bi 2 O 5样品的晶体结构、比表面积、形貌、表面化学状态和吸收性能的影响。在La含量较低（3和5摩尔%）的样品中没有检测到杂质相的痕迹，而在La含量较高（8和10摩尔%）的Sr 2Bi 2 O 5样品中观察到诸如Sr 6 Bi 2 O 9和SrCO 3的杂质相。Sr_2Bi_2 O_5的Brunauer-Emmett-Teller比表面积随La含量的增加而略有增加。高分辨率透射电子显微镜显示，未掺杂和La掺杂的Sr 2Bi 2 O 5样品没有非晶相清晰的晶面。同时，X射线光电子能谱表明，组成金属的价态为Sr 2+，Bi 3+和La 3+。通过拉曼散射测量确定了La在Sr 2Bi 2 O 5晶相中的溶解度极限。当La掺杂量较低时，La原子取代Bi位，而当La掺杂量较高时，Bi和Sr位均被La取代。La掺杂可以改变Sr 2Bi 2 O 5的电子结构，导致吸收边随La含量的增加而红移。在能带计算中再现了La掺杂的Sr 2Bi 2 O 5的带隙变窄。La掺杂提高了Sr 2Bi 2 O 5可见光催化氧化异丙醇的活性。
Single-phase Sr2Bi2O5was obtained by calcination of the heterobimetallic complex precursor Sr[Bi(DTPA)]·9H2O (DTPA is diethylenetriaminepentaacetic acid) at 700 °C for 6 h. The effect of La doping on the crystal structure, surface area, morphology, surface chemical state, and absorption properties of Sr2Bi2O5samples prepared from Sr[Bi(DTPA)]·9H2O were investigated. No traces of an impurity phase were detected in samples with a lower La content (3 and 5 mol%), while impurity phases such as Sr6Bi2O9and SrCO3were observed in Sr2Bi2O5samples with larger La contents of 8 and 10 mol%. The Brunauer–Emmett–Teller surface area of Sr2Bi2O5increased slightly with the content of La. High-resolution transmission electron microscopy revealed clear crystalline planes for both undoped and La-doped Sr2Bi2O5samples without amorphous phases. Meanwhile, X-ray photoelectron spectroscopy indicated that the valence states of constituent metals were Sr2+, Bi3+, and La3+. The solubility limit of La in the Sr2Bi2O5crystal phase was determined from Raman scattering measurements. La atoms substituted Bi sites when the doping content was low, while both Bi and Sr sites were substituted with La when the content of La was high. The electronic structure of Sr2Bi2O5could be modified by La doping, resulting in a red shift of the absorption edge with increasing La content. The band-gap narrowing of Sr2Bi2O5with La-doping was reproduced in energy-band calculations. The photocatalytic activity of Sr2Bi2O5under visible-light irradiation for the oxidation of isopropanol was enhanced by doping with La.