Simultaneous Detection and Removal of Formaldehyde at Room Temperature: Janus Au@ZnO@ZIF-8 Nanoparticles

Dawei Wang,Xiang He,Hong Fang,Puru Jena,Jing-Bin Zeng,Zhiwei Li,Wei-Ning Wang,Jian Zhou

doi:10.1007/s40820-017-0158-0

Abstract

The detection and removal of volatile organic compounds (VOCs) are of great importance to reduce the risk of indoor air quality concerns. This study reports the rational synthesis of a dual-functional Janus nanostructure and its feasibility for simultaneous detection and removal of VOCs. The Janus nanostructure was synthesized via an anisotropic growth method, composed of plasmonic nanoparticles, semiconductors, and metal organic frameworks (e.g., Au@ZnO@ZIF-8). It exhibits excellent selective detection to formaldehyde (HCHO, as a representative VOC) at room temperature over a wide range of concentrations (from 0.25 to 100 ppm), even in the presence of water and toluene molecules as interferences. In addition, HCHO was also found to be partially oxidized into non-toxic formic acid simultaneously with detection. The mechanism underlying this technology was unraveled by both experimental measurements and theoretical calculations: ZnO maintains the conductivity, while ZIF-8 improves the selective gas adsorption; the plasmonic effect of Au nanorods enhances the visible-light-driven photocatalysis of ZnO at room temperature.

Highlights

Improved indoor air quality is essential for human health since people spend almost 90% of their life in various environments [1]
X-ray diffractometer (XRD) patterns confirmed that the rhombic dodecahedron is zeolitic imidazolate framework (ZIF)-8 (Fig. 2d)
To get a deeper insight into the sensitivity and selectivity of ZnO covered by ZIF-8, we studied the interaction of HCHO as well as H2O molecules on ZnO and ZIF-8 surfaces by the Density Functional Theory (DFT) calculations

Summary

Introduction

Improved indoor air quality is essential for human health since people spend almost 90% of their life in various environments [1]. In spite of these advantages, another major challenge which plasmonic metals/ZnO-based gas sensors face is their poor selectivity. These sensors may generate false responses when detecting VOCs in the presence of water (H2O) vapor [7]. Very few of these reported plasmonic noble metals/ZnO-based gas sensors exhibited satisfactory selectivity performance [8]. How to improve the selectivity performance of these gas sensors remains challenging [9, 10]

Methods

Results

Conclusion