First-Principles Investigation of Selective Gas Sensing Property of Two-Dimensional 1T-HfTe₂

In the current era of sustainable development, gas sensors are of utmost importance in areas like environment monitoring, industry, agriculture, medicine, space missions, security, etc. To meet the needs, there are critical requirements for new generation sensor materials which can rapidly detect gas molecules at very low concentrations with minimal power consumption. In this regard, 2D materials are the natural candidates for the next generation sensors due to the ultra-large surface to volume ratio, and thereby, higher interaction with the surface dopants, higher conductivity in the surface, etc. With these motivations, we here explored the potentiality of 2D 1T-HfTe₂ as a gas sensor. In this work, we explored the interactions and charge transfer of toxic CO, CO₂, NO, NO_2, and NH₃ gases with HfTe₂ sheet by standard DFT calculations and also studied the I-V response of the 2D sheet before and after adsorption of these toxic gases by NEGF (Non-Equilibrium Green's Function) method. The effect of different environmental gases on sensing has also been examined. Our result shows that semi-metallic HfTe₂ sheet can be effectively used as a resistive sensor to detect NO gas for which it has the 'high sensitivity bias window' at very low voltage.