Interface design of ZnO/Ti3C2Tx composite and study on its ammonia performance at room temperature

A high-performance ammonia (NH 3 ) gas sensor based on ZnO/Ti 3 C 2 T x composites was fabricated using the hydrothermal method. The gas sensitivity test results show that the composite of Ti 3 C 2 T x and ZnO improves the sensing performance of Ti 3 C 2 T x -based NH 3 sensor at room temperature. The response of ZnO/Ti 3 C 2 T x to 200 ppm NH 3 is 158.7 and the response/recovery time is 3.6 s/0.9 s. Additionally, the sensor demonstrated excellent humidity resistance and long-term stability. This improvement is attributed to the introduction of additional free oxygen species and oxygen vacancies on the Ti 3 C 2 T x surface by ZnO, exposing more active metallic Ti sites. Simultaneously, reducing the number of -OH groups increases the number of -F groups and enhances the polarity of the -OH groups. DFT studies indicate that higher surface oxygen vacancy density promotes the formation of highly active and unsaturated Ti sites, thereby enhancing strong chemical adsorption of NH 3 . Concurrently, the reduction in -OH groups increases the polarity of -OH, thereby improving the adsorption efficiency of NH 3 molecules. Thus, modulating the Ti 3 C 2 T x surface with metal oxides to reduce hydroxyl groups and increase oxygen vacancies promotes the formation of Ti metal sites, offering a novel approach for developing high-performance room-temperature NH 3 gas sensors based on Ti 3 C 2 T x .