UV photosensitized N-CQDs@In2O3 ordered porous film elaborated optical fiber acetone gas sensor with ppb-level at room temperature

An optical fiber acetone gas sensor based on N-CQDs@In2O3 porous ordered thin film is proposed. The probe adopts the hollow malposition structure (HMS) to excite the evanescent field on the surface of hollow-core fiber (HCF). N-CQDs@In2O3 porous and ordered thin film was formed on the surface of optical fiber after calcining polystyrene (PS) microspheres at high temperature. The experimental results reveal the ultraviolet (UV) sensitization function for the proposed sensor at room temperature. The enhanced sensitivity is 7.1 pm/ppm, which is similar to 5.9 times of the spiritual density of unsensitized sensor. In addition, the sensor has a limit of detection (LOD) of 500 ppb and excellent time response characteristics (response time 6.2 s and recovery time 7.1 s). The sensitization mechanism of N-CQDs to In2O3 is explained by the results of the universal density function (DFT). The frontier electron orbital studies show that N-CQDs@In2O3 has more abundant electron clouds. The good moisture resistance enables its stable performance in humid environment. UV sensitization is an effective way to improve the sensitivity of optical fiber gas sensor, which is of great significance for detecting the acetone gas with ultra-low concentration.