Fabrication of iron-doped titanium dioxide quantum dots/molybdenum disulfide nanoflower for ethanol gas sensing

Junfeng Wu; Dongzhi Zhang; Yuhua Cao

doi:10.1016/j.jcis.2018.06.049

Fabrication of iron-doped titanium dioxide quantum dots/molybdenum disulfide nanoflower for ethanol gas sensing

J Colloid Interface Sci. 2018 Nov 1:529:556-567. doi: 10.1016/j.jcis.2018.06.049. Epub 2018 Jun 20.

Authors

Junfeng Wu¹, Dongzhi Zhang², Yuhua Cao¹

Affiliations

¹ College of Information and Control Engineering, China University of Petroleum (East China), Qingdao 266580, China.
² College of Information and Control Engineering, China University of Petroleum (East China), Qingdao 266580, China. Electronic address: dzzhang@upc.edu.cn.

PMID: 29958114
DOI: 10.1016/j.jcis.2018.06.049

Abstract

In this paper, a high-performance ethanol sensor based on iron (Fe)-doped titanium dioxide (TiO₂)/molybdenum disulfide (MoS₂) nanocomposite was demonstrated. Flower-like MoS₂ and Fe-TiO₂ quantum dots (QDs) were synthesized by a facile hydrothermal route, and the Fe-TiO₂/MoS₂ composite was prepared via layer-by-layer (LbL) self-assembly technique. The Fe-TiO₂/MoS₂ film sensor was fabricated on a flame resistant (FR-4) epoxy substrate with interdigital electrodes. The microstructure, elementary composition, and morphology of the as-prepared samples were fully characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of the Fe-TiO₂/MoS₂ film sensor were determined at room temperature upon exposure to different concentration of ethanol gas. The experimental results illustrated that high response, short response/recovery time, stable repeatability, excellent selectivity long-term stability, and a detection limit of low ppb level was achieved by the Fe-TiO₂/MoS₂ sensor. The underlying sensing mechanism of the Fe-TiO₂/MoS₂ sensor toward ethanol is explored through systematically experimental investigation combining with first-principle density-functional theory (DFT) simulations. The enhanced ethanol sensing properties were ascribed to the Fe³⁺ ion doping, and p-n heterojunctions created at interfaces of n-type Fe-TiO₂ and p-type MoS₂.

Keywords: Density-functional theory; Ethanol sensor; Layer-by-layer self-assembly; Molybdenum disulfide; Titanium dioxide.