DFT Investigation on Transition-Metal Cr-, Mo-, and W-Doped MXene Nb<sub>2</sub>CO<sub>2</sub> Nanosheets: Implications for High-Performance H<sub>2</sub>, CO, and H<sub>2</sub>S Gas Sensors
Xiaoyu You, Peisi Yin, Kai Zhang, Huaian Fu, Fei Song, Shanshan Yu, Zhipeng Tang, Chen Yang, Shuli Wei, Qingkuan Meng, Qiang Jing, Bo Liu
Abstract
As a prominent member of the two-dimensional (2D) material family, MXenes possess abundant active sites, a large specific surface area, metallic conductivity, and tunable surface chemistry, making them promising candidates for the fabrication of high-performance gas sensors. In this study, DFT calculations using the PBE-D3 method were employed to investigate the properties of transition metal-doped MXene Nb 2 CO 2 (doped with Cr, Mo, and W) and to systematically evaluate their gas sensing performance toward H 2, CO, and H 2 S. The gas sensing performance of the materials was analyzed from the perspective of adsorption energy, charge transfer, bond length variations of target gas molecules, density of states (DOS), and projected density of states (PDOS). The results revealed that transition metal doping significantly enhances the gas sensing capabilities of Nb 2 CO 2 . From the perspective of sensing materials, Cr-, Mo-, and W-doped Nb 2 CO 2 are suitable for CO gas sensor fabrication, while W-doped Nb 2 CO 2 exhibits superior performance for H 2 sensing. From the perspective of target gases, a high-performance H 2 gas sensor can be fabricated by using W-doped Nb 2 CO 2 . Due to the lower adsorption energy of the H 2 molecule on the surface of W-doped Nb 2 CO 2 and the larger amount of charge transferred between them, the sensor may operate at room temperature. High-performance CO gas sensors can be developed by using Cr-, Mo-, and W-doped Nb 2 CO 2 . For the same reason, a CO gas sensor based on W-doped Nb 2 CO 2 may also operate at room temperature. Additionally, Mo-doped Nb 2 CO 2 emerges as an optimal candidate for developing a high-performance H 2 S gas sensor. These findings provide valuable insights into the rational design and optimization of MXene-based gas sensors for the effective detection of H 2, CO, and H 2 S.