Facile Synthesis of ZnO/WO3 Nanocomposite Porous Films for High-Performance Gas Sensing of Multiple VOCs

Abstract

Volatile organic compounds (VOCs) in indoor environments have typical features of multiple components, high concentration, and long duration. The development of gas sensors with high sensitivity to multiple VOCs is of great significance to protect human health. Herein, we proposed a sensitive ZnO/WO3 composite chemi-resistive sensor facilely fabricated via a sacrificial template approach. Based on the transferable properties of self-assembled monolayer colloidal crystal (MCC) templates, two-dimensional honeycomb-like ordered porous ZnO/WO3 sensing matrixes were constructed in situ on commercial ceramic tube substrates with curved and rough surfaces. The nanocomposite thin films are about 250 nm in thickness with large-scale structural consistency and integrity, which facilitates characteristic responses with highly sensitivity and reliability. Furthermore, the nanocomposite sensor shows simultaneous responses to multiple VOCs that commonly exist in daily life with an obvious suppression sensing for traditional flammable gases. Particularly, a detection limit of 0.1 ppm with a second-level response/recovery time can be achieved, which is beneficial for real-time air quality assessments. We proposed a heterojunction-induced sensing enhancement mechanism for the ZnO/WO3 nanocomposite film in which the formation of abundant heterojunctions between ZnO and WO3 NPs significantly increases the thickness of the electron depletion layer in the bulk film and improves the formation of active oxygen species on the surface, which is conducive to enhanced responses for reducing VOC gases. This work not only provides a simple approach for the fabrication of high-performance gas sensors but also opens an achievable avenue for air quality assessment based on VOC concentration detection.

Highly efficient ZnO/WO3 nanocomposites towards photocatalytic gold recovery from industrial cyanide-based gold plating wastewater

“…15 and 25 wt%), additional peaks at 30.46°, 30.71° and 31.5° were observed, matching to the diffraction of (− 111), (111) and (020) lattice planes of monoclinic ZnWO 4 (JCPDS file no. 15-0774) 41 .

Figure 2 ( a ) XRD pattern and ( b ) Raman spectra of ZnO/WO 3 nanocomposites.

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“…This indicated a high stability and reusability of the hydrothermally synthesized ZnO/WO 3 nanocomposites. The resultant Au decorated ZnO/WO 3 (Au/ZnO/WO 3 ) obtained from this work may be used for other applications such as desulfurization of thiophene 36 , H 2 O 2 production 37 , or gas sensing 41 . However, the application of resultant Au/ZnO/WO 3 was not conducted in the work due to it beyonds the scope.…”

Functional Nanomaterials for Sensing and Detection

“…Via a sacrificial template approach, H. Zhang et al fabricated a two-dimensional honeycomb-like ordered porous ZnO/WO 3 composite sensing matrix on a commercial ceramic tube with a curved and rough surface as a high-performance chemiresistive sensor, and they achieved efficient detection of trace volatile organic compound gases with a considerably low detection limit [ 1 ], whereas Jolly Bhadra et al designed two-dimensional (MoS 2 , WS 2 )/PANI nanocomposites and developed ammonia sensors that operate at room temperature and have high sensitivity [ 2 ]. Both presented new functional nanomaterials for gas sensing devices.…”

Sensing Mechanism and Characterization of NO2 Gas Sensors Using Gold-Black NP-Decorated Ga2O3 Nanorod Sensing Membranes

“…In recent years, several materials have been used to fabricate gas sensors. Among them, metal oxide materials, such as zinc oxide (ZnO), 4,5 indium oxide (In 2 O 3 ), 6,7 tungsten trioxide (WO 3 ), 8,9 and gallium oxide (Ga 2 O 3 ), 10,11 have garnered significant attention due to their low cost, simple fabrication, small size, and ease manipulation. 12−16 In view of their considerable surface-to-volume ratio and more surface gas adsorption sites, nanomaterials and nanostructures are deliberately applied to the gas sensors to improve their performances.…”

“…In recent years, several materials have been used to fabricate gas sensors. Among them, metal oxide materials, such as zinc oxide (ZnO), , indium oxide (In 2 O 3 ), , tungsten trioxide (WO 3 ), , and gallium oxide (Ga 2 O 3 ), , have garnered significant attention due to their low cost, simple fabrication, small size, and ease manipulation. − In view of their considerable surface-to-volume ratio and more surface gas adsorption sites, nanomaterials and nanostructures are deliberately applied to the gas sensors to improve their performances. − In spite of the fact that homojunctions are formed between nanostructures to improve the sensitivity of gas sensors, , the formation of p–n heterojunctions between nanostructures can effectively promote the sensitivity and the resistance change. − Recently, to further enhance the performances of gas sensors by using an enhanced metal spillover phenomenon, the structures of metal-decorated metal oxide nanorods have been extensively studied and developed. − …”