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

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 to100 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.