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

Carbon dioxide (CO2) emissions pose significant threats to human health and the environment. Developing highly sensitive CO2 sensors operating at room temperature is critical for environmental and industrial applications. This study introduces a room-temperature CO2 sensing platform based on polyethyleneimine/polyethylene glycol-functionalized zinc oxide nanowires (PEI/PEG-ZnONWs) composites. Under ambient conditions (25 degrees C, 45% relative humidity), the sensor demonstrates a high response of 67% to 5000 ppm CO2, 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 CO2 changes in plants, distinguishing respiration from photosynthesis. These findings highlight the potential of PEI/PEG-ZnONWs sensors for CO2 detection in industrial safety, environmental surveillance, and healthcare.