Optical fiber triethylamine room temperature gas sensor based on HMS platform with DFT calculation and Experimental Demonstration

An optical fiber triethylamine (TEA) gas sensor based on a hollow malposition structure (HMS) platform with CQDs@BiOBr gas-sensing layer is proposed. The CQDs@BiOBr gas-sensing material is coated onto the surface of the hollow core fiber (HCF) using a dip-coating method. The misaligned structure is designed to guide light transmission within the cladding of the HCF and excite the evanescent field. The heterojunction formed between CQDs and BiOBr enhances the separation efficiency of electron-hole pairs, improving the transfer speed of charge carriers during the gas adsorption process. Experimental results show that the sensitivity of sensor at room temperature is 3.53 pm/ppm, which is 2.43 times higher compared to a sensor coated with BiOBr alone. Additionally, the response and recovery times of sensor are 12 s and 36 s, respectively, with a limit of detection (LOD) of 5.67 ppm. DFT calculations provide insight into the electronic transfer pathways and electron cloud distribution during the gas adsorption process, further validating the crucial role of the CQDs@BiOBr heterojunction in enhancing gas-sensing performance. The proposed optical fiber TEA gas sensor shows significant potential for applications in environmental monitoring and industrial safety.