Thickness dependence of proton conductivity of anodic ZrO 2-WO 3-SiO 2 nanofilms

Ke Ye, Yoshitaka Aoki, Etsushi Tsuji, Shinji Nagata, Hiroki Habazaki

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Amorphous ZrO 2-WO 3-SiO 2 nanofilms are simply prepared by anodizing of sputter-deposited Zr 37W 47Si 16 alloy at several formation voltages for 1.8 ks in 0.1 mol dm -3 phosphoric acid electrolyte at 20 °C. Efficient proton conductivity was observed after thermal treatment at 250 °C with the conductivity enhanced by reducing the film thickness. The conductivity is enhanced more than one order of magnitude by reducing the thickness from 300 to 140 nm. The anodic oxide films consist of two layers, comprising a thin outer ZrO 2 layer free from silicon and tungsten species and an inner main layer containing all zirconium, silicon and tungsten species. The thickness-dependent conductivity of the anodic ZrO 2-WO 3-SiO 2 films is associated with the conductivity of the outer ZrO 2 layer, which increases exponentially with reducing the film thickness. The area-specific resistivity of 0.14 Ω cm 2, which is below the minimum requirement (0.2 Ω cm 2) for a practical electrolyte membrane in commercial fuel cells, is achieved at a temperature at 225 °C for 100 nm-thick anodic ZrO 2-WO 3-SiO 2 films.

Original languageEnglish
Pages (from-to)194-200
Number of pages7
JournalJournal of Power Sources
Volume205
DOIs
Publication statusPublished - 2012 May 1

Keywords

  • Amorphous materials
  • Anodic oxidation
  • Ion conducting materials
  • Nanofilms
  • Proton transport

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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