Room Temperature Mo2CTx MXene Sensor for Selective Detection of ppb-Level H2S

The sensitive and selective detection of ppb-level (ppb: parts per billion) H 2 S using miniaturized and portable gas sensor is of great significance in environmental monitoring, medical diagnosis and many other fields. MXenes, with high electrical conductivity, large surface area, and abundant active sites, hold great promise for room temperature gas sensing applications. In this work, a room temperature H 2 S sensor was constructed utilizing Mo 2 CT x MXene sensitive material, synthesized by a typical LiF/HCl etching method. The H 2 S sensing characteristics of Mo 2 CT x sensor were further improved by controlling ultrasonic time and optimizing heat-treated temperature. The M-50 sensor utilizing optimized Mo 2 CT x sensing material exhibited good selectivity, the highest response value (−39.92%) to 1 ppm (ppm: parts per million) H 2 S, and the lowest detection limit of 30 ppb (theoretically 0.35 ppb). The enhanced H 2 S sensing properties are largely attributed to the fragmented nanosheet structure and surface defects caused by prolonging ultrasonic time and adjusting treatment temperature. Additionally, density functional theory (DFT) calculations demonstrated that surface Mo atom vacancy and edge of Mo 2 CT x could significantly improve the adsorption ability of H 2 S. The present work contributes to advancing exploration of Mo 2 CT x material in sensing applications.