Monomolecular‐Layer Ba5Ta4O15 Nanosheets: Synthesis and Investigation of Photocatalytic Properties
Monomolecular‐Layer Ba5Ta4O15 Nanosheets: Synthesis and Investigation of Photocatalytic Properties
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DOI：
10.1002/adfm.200500849
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发表时间：
2006-08
影响因子：
19
通讯作者：
Tongguang Xu;Chuang Zhang;Xiang Shao;Kai Wu;Yongfa Zhu
中科院分区：
文献类型：
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作者：
Tongguang Xu;Chuang Zhang;Xiang Shao;Kai Wu;Yongfa Zhu
采用水热法制备了具有六方结构的单分子层钙钛矿Ba5Ta4O15纳米片。纳米片的厚度约为1.1 nm，相当于单层Ba5Ta4O15分子，横向尺寸在50 ~ 200 nm之间。形成纳米片的最佳条件是将反应物保持在270°C以上24小时。根据对影响纳米片形成的因素（如反应时间、温度和碱度）的观察，提出了溶解-再结晶机制。在高浓度OH -下，Ba5Ta4O15纳米片的形成优先于其他纳米结构，因为OH -离子对c轴生长的阻碍作用很强。因此，多面体在单层上的扩展生长速度比单层的叠加速度要快得多，并且晶体更容易沿着a -面和b -面生长。Ba5Ta4O15纳米片对罗丹明B和气态甲醛的降解表现出较高的光催化活性。层状钙钛矿可能通过促进光生电子和空穴的电荷分离和离域来影响光催化活性。
Monomolecular‐layer perovskite Ba5Ta4O15 nanosheets with hexagonal structure have been synthesized by a hydrothermal method. The thickness of the nanosheets is about 1.1 nm, which corresponds to a monolayer of Ba5Ta4O15 molecules, with the lateral size ranging from 50 to 200 nm. The optimal conditions for the formation of the nanosheets are maintaining the reactants above 270 °C for 24 h. A dissolution–recrystallization mechanism is suggested based on observations of the factors that influence nanosheet formation, such as reaction time, temperature, and basicity. Formation of Ba5Ta4O15 nanosheets takes precedence over other nanostructures under high concentrations of OH– because the hindering effect of OH– ions on the c‐axis growth is strong. Thus, the extended growth rate of polyhedrons on one monolayer is much faster than the superposition rate of the monolayer, and the crystal grows more easily along the a‐ and b‐planes. The Ba5Ta4O15 nanosheets show a high photocatalytic activity in the degradation of Rhodamine B and gaseous formaldehyde. The layered perovskite probably affects the photocatalytic activity by promoting the charge separation and delocalization of photogenerated electrons and holes.