Issue 9, 2021

MEMS-compatible, gold nanoisland anchored 1D aligned ZnO heterojunction nanofibers: unveiling the NO2 sensing mechanism with operando photoluminescence studies

Abstract

Production and alignment of heterojunction metal oxide semiconductor nanomaterial-based sensing elements for microsensor devices have always posed fabrication challenges since they involve multi-step synthesis processes. Herein, we demonstrate a coaxial electrospinning with an in situ photoreduction process for the fabrication of MEMS-compatible, 1D aligned gold nanoisland (GNI) anchored ZnO-based Heterojunction Nanofibers (HNFs) and their complex plasmon-mediated NO2 gas sensing mechanism has been investigated using operando photoluminescence studies. Evaluation of the gas sensing properties of aligned ZnO-GNI HNFs has exhibited excellent sensor response (196%) with rapid response time towards 500 ppb NO2 gas at reduced operating temperature (200 °C). Operando studies using photoluminescence and electrical measurements ascertained the existence of supplementary active sites in the multicrystalline nanofibers owing to the existence of Au nanograins over aligned ZnO nanofibers (NFs), thereby inducing a spill-over zone and aiding the charge transfer phenomenon. The operando PL studies also revealed the plasmonic effect of metallic Au and the role of zinc interstitial (Zni) defects and oxygen vacancies (V+o), which influence the charge transfer between ZnO and surface anchored Au nanoislands. This study revealed atomistic insights into the structural defects and charge transport properties of metal oxide semiconductor heterojunction materials, and the coaxial integration method of 1D aligned ZnO-GNI HNFs paves the way for unique strategies and the development of suitable MEMS based gas sensors for real-time applications.

Graphical abstract: MEMS-compatible, gold nanoisland anchored 1D aligned ZnO heterojunction nanofibers: unveiling the NO2 sensing mechanism with operando photoluminescence studies

Supplementary files

Article information

Article type
Paper
Submitted
01 Febr. 2021
Accepted
08 Marts 2021
First published
09 Marts 2021
This article is Open Access
Creative Commons BY license

Mater. Adv., 2021,2, 3000-3013

MEMS-compatible, gold nanoisland anchored 1D aligned ZnO heterojunction nanofibers: unveiling the NO2 sensing mechanism with operando photoluminescence studies

R. Vishnuraj, J. Dhakshinamoorthy, K. G. Nair, M. Aleem and B. Pullithadathil, Mater. Adv., 2021, 2, 3000 DOI: 10.1039/D1MA00094B

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