Electrochemical Characteristic on Hydrogen Intercalation into the Interface between Electrolyte of the 0.1N H2SO4and Amorphous Tungsten Oxides Thin Film Fabricated by Sol-Gel Method

졸-겔법으로 제조된 비정질의 텅스텐 산화물 박막과 황산 전해질 계면에서 일어나는 수소의 층간 반응에 대한 전기화학적 특성

  • Kang, Tae-Hyuk (Dept. of Chemical Engineering, Hongik University) ;
  • Min, Byoung-Chul (Dept. of Environmental Technology, Changwon Polytechnic College) ;
  • Ju, Jeh-Beck (Dept. of Chemical Engineering, Hongik University) ;
  • Sohn, Tae-Won (Dept. of Chemical Engineering, Hongik University) ;
  • Cho, Won-Il (Div. of Chemical Engineering, KIST)
  • 강태혁 (홍익대학교 화학공학과) ;
  • 민병철 (창원기능대학 환경기술학과) ;
  • 주재백 (홍익대학교 화학공학과) ;
  • 손태원 (홍익대학교 화학공학과) ;
  • 조원일 (한국과학기술연구원 화공연구부)
  • Received : 1996.06.25
  • Accepted : 1996.11.11
  • Published : 1996.12.10

Abstract

The peroxo-polytungstic acid was formed by the direct reaction of tungsten powder with the hydrogen peroxide solution. Peroxo-polytungstic powder were prepared by rotary evaporator using the fabricated on to ITO coated glass as substrate by dip-coating method using $2g/10mL(W-IPA/H_2O)$ sol solution. A substrate was dipped into the sol solution and after a meniscus had settled, the substrate was withdrawn at a constant rate of the 3mm/sec. Thicker layer could be built up by repeated dipping/post-treatment 15 times cycles. The layers dried at the temperature of $65{\sim}70^{\circ}C$ during the withdrawn process, and then tungsten oxides thin film was formed by final heating treatment at the temperature of $230{\sim}240^{\circ}C$ for 30min. A linear rotation between the thickness of thin film and the number of dipping/post-treatment cycles for tungsten oxides thin films made by dip-coating was found. The thickness of thin film had $60{\AA}$ after one dipping. From the patterns of XRD, the structure of tungsten oxides thin film identified as amorphous one and from the photographs of SEM, the defects and the moderate cracks were observed on the tungsten oxides thin film, but the homogeneous surface of thin films were mostly appeared. The electrochemical characteristic of the $ITO/WO_3$ thin film electrode were confirmed by the cyclic voltammetry and the cathodic Tafel polaization method. The coloring bleaching processes were clearly repeated up to several hundreds cycles by multiple cyclic voltammetry, but the dissolved phenomenon of thin film revealed in $H_2SO_4$ solution was observed due to the decrease of the current densities. The diffusion coefficient was calculated from irreversible Randles-Sevick equation from the data obtained by the cyclic voltammetry with various scan rates.

Keywords

Acknowledgement

Supported by : 과학재단

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