Highly sensitive detection toward aniline vapor promoted by heterojunction between covalent organic frameworks and biocarbon

Development of sensors for detecting aniline for environment, food quality, and medical diagnostics is highly anticipated. However, the high operating temperatures of current aniline sensors hinder their practical use. In this work, the carbon material with micron tube structure (CMTs) derived from lavender straw was used as a template, and the imine covalent organic frameworks (iCOF) was synthesized on the CMTs template at room temperature, forming the iCOF-CMTs with a heterojunction structure. This pioneering study combines COFs materials with biocarbon materials for the first time, allowing us to compare the gas sensing properties of iCOF, CMTs and iCOF-CMTs composites. Due to the presence of heterojunction, the iCOF-CMTs composites exhibited the good gas-sensitive properties among the three materials, especially for aniline vapor. The iCOF-CMTs sensors were tested at room temperature to eight different gases, with the highest response of 2155.75 % for aniline. For the iCOF-CMTs sensor to aniline, the sum of response and recovery times does not exceed 26 s in a response-recovery cycle, and the limit of detection reached 10.26 ppb. This study demonstrated that the special heterojunction structure greatly improved the sensing performance of iCOF and CMTs, providing ideas for further development of COFs-based gas sensors.