On-chip grown ZnO nanosheet-array with interconnected nanojunction interfaces for enhanced optoelectronic NO2 gas sensing at room temperature

Jing Wang; Mingying Yu; Yi Xia; Xian Li; Cheng Yang; Sridhar Komarneni

doi:10.1016/j.jcis.2019.06.085

On-chip grown ZnO nanosheet-array with interconnected nanojunction interfaces for enhanced optoelectronic NO₂ gas sensing at room temperature

J Colloid Interface Sci. 2019 Oct 15:554:19-28. doi: 10.1016/j.jcis.2019.06.085. Epub 2019 Jun 27.

Authors

Jing Wang¹, Mingying Yu², Yi Xia³, Xian Li⁴, Cheng Yang², Sridhar Komarneni⁵

Affiliations

¹ Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China. Electronic address: jingwang@jiangnan.edu.cn.
² Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
³ Research Center for Analysis and Measurement & Analytic & Testing Research Center of Yunnan, Kunming University of Science and Technology, Kunming 650093, China.
⁴ Agricultural Information Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Agricultural Information Service Technology of Ministry of Agriculture, Beijing 100081, China.
⁵ Department of Ecosystem Science and Management and Materials Research Institute, 204 Energy and the Environment Laboratory, The Pennsylvania State University, University Park, PA 16802, USA. Electronic address: sxk7@psu.edu.

PMID: 31265965
DOI: 10.1016/j.jcis.2019.06.085

Abstract

Herein, we demonstrated the on-chip growth of nanostructured ZnO films with abundant nanojunctions for the fabrication of high-performance optoelectronic NO₂ sensors. A fast solution approach allowed the controllable growth of ZnO nanorod- and nanosheet-arrays directly on flexible substrates, which were endowed with abundant nanojunctions. Electron microscopy observations revealed the existence of two types of the nanojunction interfaces, i.e., the attached and interconnected interfaces within the nanostructure networks. Compared with the attached nanorods, the optoelectronic NO₂ sensors based on interconnected ZnO nanosheets showed higher responses and faster response/recovery rates under UV illumination at room temperature. The responses of the nanosheet-based sensor ranged from 28% to 610% toward NO₂ concentrations of 10 ppb to 1000 ppb. Moreover, the optoelectronic sensors exhibited excellent reversibility, and mechanical and long-term stabilities along with low detection limits. The enhanced optoelectronic NO₂ sensing properties of the interconnected ZnO nanosheets could be attributed to different types of nanojunction interfaces, which played a key role in modulating the interfacial potential barrier heights of the nanojunctions according to the surface depletion model. The presently developed strategy of nanojunction interface engineering is expected to have wide interest for semiconductor-based sensor applications.

Keywords: Nanojunction interfaces; Potential barrier heights; Room temperature NO(2) sensor; UV illumination; ZnO nanosheet array.