Issue 10, 2020

Boosting the performance of NO2 gas sensors based on n–n type mesoporous ZnO@In2O3 heterojunction nanowires: in situ conducting probe atomic force microscopic elucidation of room temperature local electron transport

Abstract

Herein, n–n type one dimensional ZnO@In2O3 heterojunction nanowires have been developed and their local electron transport properties during trace-level NO2 gas sensing process have been probed at room-temperature using conducting probe atomic microscopy. Solvothermally synthesized 1D ZnO@In2O3 heterojunction nanowires have been characterized by various spectroscopic and microscopic techniques, which revealed the mesoporous structure indicating their enhanced sensing properties. The dangling bonds and fraction of metal ions to oxygen ions existing on the exposed crystal facets of the heterojunction nanowires have been visualized by employing crystallographic simulations with TEM analysis, which aided in forecasting the nature of surface adsorption of NO2 gas species. In situ electrical characteristics and Scanning Spreading Resistance Microscopic (SSRM) imaging of single ZnO@In2O3 heterojunction nanowires revealed the local charge transport properties in n–n type ZnO@In2O3 heterojunction nanowires. Moreover, the ZnO@In2O3 heterojunction nanowires based sensor exhibited excellent sensitivity (S = 274%), a fast response (4–6 s) and high selectivity towards trace-level concentration (500 ppb) of NO2 gas under ambient conditions with low power consumption. Spatially resolved surface potential (SP) variations in ZnO@In2O3 heterojunction nanowires have been visualized using in situ Scanning Kelvin Probe Force Microscopy (SKPM) under NO2 gas environment at room temperature, which was further correlated with its energy band structure. The work functions of the material evaluated by SKPM reveal considerable changes in the energy band structure owing to the local electron transport between ZnO and In2O3 at the heterojunctions upon exposure to NO2 gas indicating the charge carrier recombination. A plausible mechanism has been proposed based on the experimental evidences. The results suggest that new insights into complex sensing mechanisms deduced from the present investigation on n–n type MOS based heterojunction nanowires under ambient conditions can pave the way for the novel design and development of affordable and superior real-time gas sensors.

Graphical abstract: Boosting the performance of NO2 gas sensors based on n–n type mesoporous ZnO@In2O3 heterojunction nanowires: in situ conducting probe atomic force microscopic elucidation of room temperature local electron transport

  • This article is part of the themed collection: Gas sensing

Supplementary files

Article information

Article type
Paper
Submitted
23 Apr. 2020
Accepted
10 Aug. 2020
First published
12 Aug. 2020
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2020,2, 4785-4797

Boosting the performance of NO2 gas sensors based on n–n type mesoporous ZnO@In2O3 heterojunction nanowires: in situ conducting probe atomic force microscopic elucidation of room temperature local electron transport

R. Vishnuraj, K. K. Karuppanan, M. Aleem and B. Pullithadathil, Nanoscale Adv., 2020, 2, 4785 DOI: 10.1039/D0NA00318B

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements