Atomic and electronic properties in the Electrochromic VOx/graphene films determined by XAS

• Main Authors: Bo-Yan Lu, 盧柏諺
• Other Authors: 魏大華
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/kq483g

碩士 === 國立臺北科技大學 === 製造科技研究所 === 102 === 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.