On-chip rapid CO2 detection at room-temperature based on ultraviolet light activation to enhance electron-molecule interactions

Carbon dioxide (CO 2 ) emissions pose significant threats to human health and the environment. Developing highly sensitive CO 2 sensors operating at room temperature is critical for environmental and industrial applications. This study introduces a room-temperature CO 2 sensing platform based on polyethyleneimine/polyethylene glycol-functionalized zinc oxide nanowires (PEI/PEG-ZnONWs) composites. Under ambient conditions (25 °C, 45% relative humidity), the sensor demonstrates a high response of 67% to 5000 ppm CO 2 , with rapid response and recovery times of 13 s and 61 s, respectively. Notably, ultraviolet (UV) (365 nm) activation enhances photogenerated carrier separation, significantly accelerating gas-sensitive kinetics and reducing response/recovery times to 5 s and 19 s, respectively. The sensor demonstrates excellent selectivity, stability, and reproducibility. Mechanistic studies attribute this enhancement to the amine-rich active sites introduced by PEI/PEG functionalization and the high surface area of ZnONWs, which facilitate gas adsorption/desorption dynamics and optimize charge transport through conductive pathways. Finally, the platform enables real-time monitoring of dynamic CO 2 changes in plants, distinguishing respiration from photosynthesis. These findings highlight the potential of PEI/PEG-ZnONWs sensors for CO 2 detection in industrial safety, environmental surveillance, and healthcare.