纳米WO3块体材料的电致变色效应

WO3薄膜能够通过电、光、热变色.实验发现纳米WO3块材具有明显的常规块材不具有的电致变色特性，即当样品中有电流通过时，样品从负极到正极颜色由黄色变为深蓝色.变色前后样品的显微形貌和相结构都没有明显变化.x射线光电子能谱说明变色后的样品中出现了低价的钨离子(W5+).根据实验结果，变色过程被认为是一种电子注入效应.纳米样品中的高价钨离子(W6+)因为纳米材料的表面效应而具有足够大的活性，能与电子结合生成低价的离子，从而使样品变色. 关键词： WO3块材 纳米材料 电致变色

Electrochromic effect of nanostructured WO3 bulk

WO3 films are well known for the change of their color through electro, photo and thermo chromism. We report here that the nanostructured WO3 bulk has an obvious electrochromic effect, which does not exist in ordinary WO3 bulk. The sample turns to a deep blue color upon changing from anode to cathode when external voltage is applied. There is no difference of the microstructure and phase structure between the colored and uncolored samples. X-ray photoelectron spectroscopy analysis shows that low valence state of tungsten ion (W5+) existed in the colored samples. Based on the experimental results, it is concluded that the coloration is an electron-injection effect. The high valence state of tungsten ion (W6+) in nanostructured WO3 bulk has enough activity to combine with electron and turns to the low valence state counterpart because of the surface effects of nanostructured materials. As a consequence, the sample changes its color.