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

The sensitive and selective detection of ppb-level (ppb: parts per billion) H2S 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 H2S sensor was constructed utilizing Mo2CTx MXene sensitive material, synthesized by a typical LiF/HCl etching method. The H2S sensing characteristics of Mo2CTx sensor were further improved by controlling ultrasonic time and optimizing heat-treated temperature. The M-50 sensor utilizing optimized Mo2CTx sensing material exhibited good selectivity, the highest response value (-39.92%) to 1 ppm (ppm: parts per million) H2S, and the lowest detection limit of 30 ppb (theoretically 0.35 ppb). The enhanced H2S 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 Mo2CTx could significantly improve the adsorption ability of H2S. The present work contributes to advancing exploration of Mo2CTx material in sensing applications.