Enhanced Sensing Ability of Brush-Like Fe2O3-ZnO Nanostructures towards NO2 Gas via Manipulating Material Synergistic Effect.

Yuan-Chang Liang,Yu-Wei Hsu

doi:10.3390/ijms22136884

Yuan-Chang Liang, Yu-Wei Hsu

Open Access

https://doi.org/10.3390/ijms22136884

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Abstract

Brush-like α-Fe2O3–ZnO heterostructures were synthesized through a sputtering ZnO seed-assisted hydrothermal growth method. The resulting heterostructures consisted of α-Fe2O3 rod templates and ZnO branched crystals with an average diameter of approximately 12 nm and length of 25 nm. The gas-sensing results demonstrated that the α-Fe2O3–ZnO heterostructure-based sensor exhibited excellent sensitivity, selectivity, and stability toward low-concentration NO2 gas at an optimal temperature of 300 °C. The α-Fe2O3–ZnO sensor, in particular, demonstrated substantially higher sensitivity compared with pristine α-Fe2O3, along with faster response and recovery speeds under similar test conditions. An appropriate material synergic effect accounts for the considerable enhancement in the NO2 gas-sensing performance of the α-Fe2O3–ZnO heterostructures.

Highlights

Increasing awareness of harmful gases as an environmental problem has resulted in the vital improvement of gas sensor technology
Hematite (α-Fe2 O3 ) and zinc oxide (ZnO) are n-type semiconductors widely researched in gas sensor applications owing to their superior stability, low cost, and preparation simplicity [1,2]
Promising research into oxide heterostructures consisting of Fe2 O3 and ZnO has indicated that a Fe2 O3 –ZnO composite system can improve the detection ability toward various harmful gases in comparison with that of single-constituent counterparts

Summary

Introduction

Increasing awareness of harmful gases as an environmental problem has resulted in the vital improvement of gas sensor technology. Hematite (α-Fe2 O3 ) and zinc oxide (ZnO) are n-type semiconductors widely researched in gas sensor applications owing to their superior stability, low cost, and preparation simplicity [1,2]. Despite the encouraging development of low-degree α-Fe2 O3 and ZnO nanostructures, the improvement of their gas sensitivity and selectivity to target gases remains a challenge. Promising research into oxide heterostructures consisting of Fe2 O3 and ZnO has indicated that a Fe2 O3 –ZnO composite system can improve the detection ability toward various harmful gases in comparison with that of single-constituent counterparts. Most work on Fe2 O3 –ZnO heterostructures has been conducted on independent variables to improve their gas sensitivity; for example, controlling the thickness of the decorated ZnO shell for comparison with its

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