A vertically integrated ZnO-based hydrogen sensor with hierarchical bi-layered inverse opals

Pei Sung Hung, Yu Szu Chou, Bo Han Huang, I. Kai Cheng, Guang Ren Wang, Wei An Chung, Fu Ming Pan, Pu Wei Wu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Three-dimensionally ordered macro/mesoporous materials are known to possess a large accessible surface area with impressive permeability. In this work, we combine electrophoresis and electrodeposition to fabricate a hierarchical bi-layered inverse opaline film in which a ZnO sensing layer is stacked with an Au electrode for impressive H2 sensing activities. To enhance its responsiveness, both morphological and crystallographic properties of ZnO inverse opals are optimized using KCl as the porogen. The resulting ZnO inverse opals demonstrate a specific surface area that is three times larger over comparable ZnO inverse opals by the formation of nanoporous skeletons. In addition, the deposition bath was deliberately designed so the predominant crystallographic plane of ZnO is shifted from (10 1- 0) to (0001) as the latter exhibits superior activity toward reducing gases. Through X-ray photoelectron spectroscopy, we show a significant increase of chemisorbed oxygen on the (0001) plane. Consequently, our hierarchical bi-layered inverse opals reveal a 500 % improvement in the sensitivity toward 15 ppm H2 under 200 °C. In short, this is the first demonstration of a vertically-arranged inverse opaline film incorporating both metal and oxide layers to function as an integrated three-dimensional gas sensor with low detection limit.

Original languageEnglish
Article number128779
JournalSensors and Actuators, B: Chemical
Volume325
DOIs
StatePublished - 15 Dec 2020

Keywords

  • Colloidal crystals
  • Gas sensing
  • Hierarchical structure
  • Inverse opals
  • Nanoporous

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