First-Principles Calculations of Ti Doping-Induced Charge Transfer between Nox and Mos2 to Enhance Gas-Sensitive Sensing Performance

Abstract

Two-dimensional (2D) materials represented by transition metal sulfides are considered as one of the most promising candidates for next-generation gas-sensitive materials. Here, we constructed the 2D MoS2 monolayer structure (MS-T) doped by a transition metal Ti bulk-phase to achieve efficient adsorption for NOx by modulating the electronic structure and bonding coordination mode between the transition metal element Ti and MS. Based on the density-functional theory (DFT), the energy band structures, charge state distributions, adsorption properties and sensitivities of the adsorption systems between four carbon-nitrogen oxides (NO2, NO, CO, and CO2) and monolayer MS before and after Ti doping were systematically compared and analyzed. The results demonstrate that the favorable energy-level alignment between the Ti-3d orbitals and NOx-p orbitals induces strong interactions and significant charge exchange between gas molecules and the substrate material. Consequently, the adsorption performance of the four gas molecules in the MS-T system is markedly enhanced, with particularly exceptional performance observed for NOx adsorption. Further, the effects of Ti doping on the energy bands and orbital hybridization were deeply analyzed to elucidate the interaction mode between MS-T and NOx. The above work provides a novel perspective for improving the NOx trapping performance of 2D TMS material systems.

Keywords: Two-dimensional material, MoS2 monolayer, Transition element doping, density functional theory