利用XAS對電致色變氧化釩/石墨烯薄膜原子與電子結構之研究

利用溶膠凝膠法製備以氧化釩(VOx)為基礎的奈米複合薄膜，藉由加入石墨烯來增加薄膜的電致色變特性。透過循環伏安法(CV)、時間電流滴定法(CA)、紫外/可見光譜(UV-Vis)以及X光吸收光譜(XAS)來研究氧化釩(VOx)/石墨烯奈米複合薄膜的電化學、光學和電子與原子特性。石墨烯被預期在鋰離子嵌入薄膜後為電荷提供傳導路徑。由薄膜在褪色態與著色態的X光吸收光譜之中V L-edge與O K-edge的變化顯示出電荷狀態與釩原子周圍軌道的對稱性差異。由延伸X光吸收光譜精細結構(EXAFS)結果進一步證明，當施加偏壓時會改變V-O鍵長與配位數。這些結果與從X光繞射和軟X光吸收光譜得到的結果是一致的。由以上結果顯示，氧化還原反應的速度與VO6氧原子八面體中心釩原子位置的對稱性有緊密的關連性。本研究中可以提供用於電致色變薄膜的節能窗戶或其他電子元件裝置的製造過程中的重要進展。

關鍵字

電致色變；氧化釩(VOx) ；石墨烯；溶膠凝膠法； X光吸收光譜

並列摘要

The electrochromic properties in VOx-based nanocomposite films that were prepared by sol-gel method are enhanced by incorporation of graphene powder. The cyclic voltammetry (CV), chronoamperometry (CA), UV-Visible spectrophotometer (UV-Vis) and X-ray absorption spectroscopy (XAS) were used to study the electrochemical and optical properties of VOx/graphene nanocomposite films. Graphene is expected to provide a conductive path for charge carrier upon the Li+ insertion. The spectral changes of V L-edge and O K-edge of the films in bleached and colored state indicate the variation of charge state and orbital symmetry around vanadium. EXAFS results further demonstrate the V-O bond lengths and coordination number (CN) are varied when the bias potential is applied. These findings are consistent with the results that obtained from XRD and soft x-ray absorption spectra. The results reveal the rate of redox reaction is strongly correlated to the position of central V ions in VO6 octahedral (Oh) symmetry. This study may provide important progress for the fabrication of electrochromic films for energy-saving windows or other useful electronic devices.

並列關鍵字

Electrochromic ； Vanadium Oxide (VOx) ； Graphene ； Sol–gel ； XAS

參考文獻

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利用XAS對電致色變氧化釩/石墨烯薄膜原子與電子結構之研究

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