Rational design of porous ultrathin Co3O4 nanosheets with oxygen vacancies for efficient chemiresistive sensing of trace acetone

Precise detection of trace acetone is crucial for industrial production safety, early disease screening, and other fields. However, semiconductor sensors face challenges in meeting the growing demand for high sensitivity and low detection limits for acetone gas due to poor detection capabilities for weak currents and low sensing activity at reaction sites. In this work, we regulate the formation rate of ZIF-67 and induce its transformation into α-Co(OH) 2 through ion exchange and etching processes on its surface, resulting in the topological formation of Co 3 O 4 porous ultrathin hierarchical nanosheets. The ultrathin nanosheets enable efficient carrier transport along the two-dimensional plane. Owing to a thickness of approximately 5 nm, the hole accumulation layers are able to merge entirely, resulting in electrical characteristics dominated by surface effects. In addition, abundant oxygen vacancies markedly enhance the chemical adsorption ability toward acetone, while the surface-rich Co 2 + configuration significantly promotes the catalytic activity of the Co 3 O 4 surface. Furthermore, the interconnected porous architecture combined with a high specific surface area (107.2 m 2 ·g −1 ) facilitates rapid gas transport and enhances adsorption efficiency. Consequently, the Co 3 O 4 porous ultrathin nanosheet-based sensor exhibits excellent sensing performance for acetone detection, achieving a response of 80.3 at 100 ppm, along with remarkable selectivity, repeatability, long-term stability, and a practical detection threshold down to 30 ppb (response of 1.12). This study proposes an effective approach for constructing Co 3 O 4 porous ultrathin hierarchical nanosheets and modulating gas-solid interface interactions through defect engineering and surface engineering, offering valuable insights for the development of high-performance acetone sensors.