High performance and highly selective sensing of triethylamine sensors based on Cu-doped MoO3 nanobelts

Developing high-performance triethylamine (TEA) gas sensors are vital for human health. Defect engineering is a common method to enhance sensor performance. In this work, Cu-doped MoO3 nanobelts with different Cu/Mo molar ratios were synthesized by a low-cost solvothermal method. The 7.5CM sensor (Cu/Mo=7.5%) exhibited a response value of 135 to 10 ppm TEA at 240 °C. The sensor also showed excellent selectivity and sub-ppm detection limit (12.5 ppb). Based on X-ray photoelectron spectroscopy (XPS) and positron annihilation lifetime spectroscopy (PALS) analysis, the enhanced gas sensing performance and mechanism of Cu-doped MoO3 were discussed. PALS results indicated that higher V′MoVo··Vo·· vacancy defect clusters content on the surface of Cu-doped MoO3. The enhanced gas sensing performance was attributed to the increased concentration of vacancies/vacancy clusters on the surface of MoO3 nanobelts due to Cu doping, which facilitated the formation of surface chemisorbed oxygen and provided more active sites for the reaction of TEA. Additionally, CuMoO4 nanocrystals formed in MoO3 nanobelts can provide p-n heterojunctions on the surface, which generates potential barrier, enabling a wide variation range for the resistance of the sensor. This work provided a simple and effective method for the application of defect engineering in gas sensing materials.