Ammonia sensing by closely packed WO3 microspheres with oxygen vacancies

Chu-Ya Wang; Xing Zhang; Qing Rong; Nan-Nan Hou; Han-Qing Yu

doi:10.1016/j.chemosphere.2018.04.050

Ammonia sensing by closely packed WO₃ microspheres with oxygen vacancies

Chemosphere. 2018 Aug:204:202-209. doi: 10.1016/j.chemosphere.2018.04.050. Epub 2018 Apr 10.

Authors

Chu-Ya Wang¹, Xing Zhang¹, Qing Rong¹, Nan-Nan Hou², Han-Qing Yu³

Affiliations

¹ CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China.
² Research Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, China.
³ CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China. Electronic address: hqyu@ustc.edu.cn.

PMID: 29656156
DOI: 10.1016/j.chemosphere.2018.04.050

Abstract

Ammonia (NH₃), is a precursor for the formation of atmospheric fine particulate matter (PM_2.5), and thus establishing efficient and cost-effective methods to detect ammonia emission is highly desired. Transition metal oxide semiconductors-based sensors for electrochemical gas sensing have been extensively explored. Among various types of semiconductors, tungsten oxide (WO₃) possesses an anisotropic layered crystalline structure and is recognized as a promising material for gas sensing. However, the performance of commercial WO₃ is unsatisfactory because of its high impedance and low charge transportation efficiency. Thus, the modification of commercial WO₃ is needed to make it an efficient ammonia sensor material. In this work, closely packed WO₃ microspheres with oxygen vacancies were synthesized successfully through a novel two-step hydrothermal route. Our WO₃ showed a good selectivity to ammonia sensing, and its response intensity was 2.6 times higher than that of commercial WO₃ because of its optimized conductivity. Moreover, the mechanism behind its robust ammonia sensing performance was elucidated. The effectiveness of the as-prepared WO₃ microspheres for ammonia sensing also suggests a new strategy for modifying transition metal oxide materials.

Keywords: Ammonia; Emission; Gas sensing; Oxygen vacancy; WO(3) microsphere.

MeSH terms

Ammonia / analysis*
Ammonia / chemistry
Microspheres*
Oxides / chemical synthesis
Oxides / chemistry*
Oxygen / chemistry
Particulate Matter / chemistry
Tungsten / chemistry*

Substances

Oxides
Particulate Matter
Ammonia
tungsten oxide
Oxygen
Tungsten