Two-step fabrication of ZnO nanosheets for high-performance VOCs gas sensor

Sheet-like ZnO nanostructure was successfully synthesized through a simple, cost-effective, and low-temperature sonochemical process followed by an etching treatment in an alkali environment at room temperature without any catalyst, template, or seed layer. The morphology and crystallinity of the products were examined by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-prepared nanosheets with high purity were single crystals and well-dispersed. A possible formation mechanism of ZnO nanosheets was proposed based on the experimental results. Micro gas sensor fabricated from the as-prepared ZnO nanosheets were tested to different concentration of volatile organic compounds (VOCs) gases. The gas-sensing results revealed that ZnO nanosheets-based micro sensor exhibited high sensitivity to acetaldehyde and formaldehyde with response time within 10 s and the detection limit down to 50 ppb. The excellent sensing property of ZnO nanosheets is mainly attributed to their large specific area, accessible surface, and less agglomerated configuration.