389711 Tungsten Trioxide/Zinc Tungstate Bilayers: Electrochromic Behaviors, Energy Storage and Electron Transfer

Tuesday, November 18, 2014: 10:00 AM
International 8 (Marriott Marquis Atlanta)
Huige Wei1, Daowei Ding1, Xingru Yan1, Jiang Guo1, Haoran Chen2, Lu Shao3, Suying Wei4, Zhanhu Guo1 and Luyi Sun5, (1)Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX, (2)Department of Chemistry and Biochemistry, Texas State University-San Marcos, San Marcos, TX, (3)Harbin Institute of Technology, Harbin, China, (4)Department of Chemistry and Biochemistry, Lamar University, Beaumont, TX, (5)Department of Chemical and Biomolecular Engineering and Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT

Materials with integrated functions of energy storage and electrochromism are highly desirable from the point of view of sustainable development.1, 2 Herein, pair-sequentially spin-coated tungsten trioxide (WO3) and zinc tungstate (ZnWO4) bilayer films onto indium tin oxide (ITO) coated glass slides have been prepared via sol-gel methods followed by annealing. The bilayers of ZnWO4/WO3 (the bilayer film consisting of an inner layer of ZnWO4 and an outer layer of WO3 on the ITO glass) and WO3/ZnWO4 (the bilayer film consisting of an inner layer of WO3 and an outer layer of ZnWO4 on the ITO glass) exhibit integrated functions of electrochromic and energy storage behaviors as indicated by the in situ spectroelectrochemistry and cyclic voltammetry (CV) results. Accordingly, blue color was observed for the bilayer films at -1 V in 0.5 M H2SO4 solution. An areal capacitance of 140 and 230 μF/cm2 was obtained for the ZnWO4/WO3, and WO3/ZnWO4 film, respectively, at a scan rate of 0.05 V/s in the CV measurements. The CV results also unveiled the electron transfer behavior between the semiconductor films in the oxidation process, suggesting a sequence-dependent electrochemical response in the bilayer films. Meanwhile, methylene blue (MB) was used as an indicator to study the electron transfer phenomenon during the reduction process at negative potentials of -0.4 and -0.8 V, in 0.5 M Na2SO4. The results indicated that the electrons transfer across the bilayers was enhanced at more negative potentials.

References

1.  H. Wei, X. Yan, S. Wu, Z. Luo, S. Wei and Z. Guo, The Journal of Physical Chemistry C, 2012, 116, 25052-25064.

2.  H. Wei, J. Zhu, S. Wu, S. Wei and Z. Guo, Polymer, 2013, 54, 1820-1831.


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