Microwave assisted synthesis of high-surface area WO3 particles decorated with mosaic patterns via hydrochloric acid treatment of Bi2W2O9
Microwave assisted synthesis of high-surface area WO3 particles decorated with mosaic patterns via hydrochloric acid treatment of Bi2W2O9
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DOI：
10.1039/c5ra15167h
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发表时间：
2015-09
期刊：
影响因子：
3.9
通讯作者：
Fuminao Kishimoto;D. Mochizuki;M. Maitani;E. Suzuki;Y. Wada
中科院分区：
文献类型：
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作者：
Fuminao Kishimoto;D. Mochizuki;M. Maitani;E. Suzuki;Y. Wada
通过水热技术，在微波加热下，使用盐酸在200 °C下，从具有Bi 2 O22+层和W2 O 72 −层的交替堆叠结构的层状钨酸铋（Bi 2 W2 O 9）合成在颗粒平面上具有镶嵌结构的单斜晶系WO 3颗粒。这些颗粒具有高的比表面积，在气态乙醛的降解中具有高的光催化活性。连续的SEM观察已经澄清了微波加热下的Bi 2 W2 O 9的结构与常规加热相比的动态转变。通过Bi 2 W2 O 9与HCl反应生产WO 3由两个反应步骤组成，即，通过用H+置换Bi 2 O22+生成H2 W2 O 7（第一步）和通过H2 W2 O 7脱水将H2 W2 O 7转化为WO 3（第二步）。第一步甚至在室温下进行，而第二步反应需要高于180 °C的温度。为了研究微波加热对第一步（Bi 2 O22+的置换）的影响，在80 °C下在微波加热和常规加热下进行Bi 2 W2 O 9和HCl的反应。研究发现，微波选择性加热效应加速了Bi_2 O_（22+）与H ~+的置换反应。有趣的是，具有马赛克图案的WO 3颗粒仅在微波加热下产生。另一方面，在HCl存在下的Bi 2 W2 O 9的常规加热导致形成没有马赛克图案的板状WO 3颗粒。
Monoclinic WO3 particles with mosaic structures on the planes of the particles were synthesized from layered bismuth tungstate (Bi2W2O9) with the alternate stacked structure of Bi2O22+ layers and W2O72− layers via a hydrothermal technique using hydrochloric acid at 200 °C under microwave heating. These particles possessed high surface areas, giving a high photocatalytic activity in the degradation of gaseous acetaldehyde. Sequential SEM observations have clarified the dynamic transformations of the structures of Bi2W2O9 under microwave heating in comparison with conventional heating. The WO3 production through the reaction of Bi2W2O9 with HCl consists of two reaction steps, i.e., H2W2O7 generation via replacement of Bi2O22+ with H+ (the first step) and conversion of H2W2O7 to WO3 through dehydration of H2W2O7 (the second step). The first step proceeds even at room temperature, while the second reaction requires temperatures above 180 °C. To investigate the microwave heating effect on the first step (the replacement of Bi2O22+), the reaction of Bi2W2O9 and HCl was carried out at 80 °C under both microwave heating and conventional heating. It has been found that the replacement of Bi2O22+ with H+ is accelerated by the microwave selective heating effect. Interestingly, the WO3 particles with mosaic patterns were produced only under microwave heating. On the other hand, conventional heating of Bi2W2O9 in the presence of HCl resulted in the formation of plate-like WO3 particles without mosaic patterns.