Atomic Plasma Grafting: Precise Control of Functional Groups on Ti 3 C 2 T x MXene for Room Temperature Gas Sensors

• Published in: ACS applied materials & interfaces Vol. 15; no. 9; pp. 12232 - 12239
• Main Authors: Wang, Ying, Fu, Jimin, Xu, Jiangang, Hu, Haibo, Ho, Derek
• Format: Journal Article
• Language: English
• Published: United States 08.03.2023
• Subjects: MXene nanosheets; plasma functional group grafting; 2D material; room temperature gas sensor; PDOS; surface functionalization
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.2c22609

Gas sensing properties of two-dimensional (2D) materials are derived from charge transfer between the analyte and surface functional groups. However, for sensing films consisting of 2D Ti C T MXene nanosheets, the precise control of surface functional groups for achieving optimal gas sensing performance and the associate mechanism are still far from well understood. Herein, we present a functional group engineering strategy based on plasma exposure for optimizing the gas sensing performance of Ti C T MXene. For performance assessment and sensing mechanism elucidation, we synthesize few-layered Ti C T MXene through liquid exfoliation and then graft functional groups via in situ plasma treatment. Functionalized Ti C T MXene with large amounts of -O functional groups shows NO sensing properties that are unprecedented among MXene-based gas sensors. Density functional theory (DFT) calculations reveal that -O functional groups are associated with increased NO adsorption energy, thereby enhancing charge transport. The -O functionalized Ti C T sensor shows a record-breaking response of 13.8% toward 10 ppm NO , good selectivity, and long-term stability at room temperature. The proposed technique is also capable of improving selectivity, a well-known challenge in chemoresistive gas sensing. This work paves the way to the possibility of using plasma grafting for precise functionalization of MXene surfaces toward practical realization of electronic devices.