Defect-Induced Sensitivity Improvement in HfNBr Monolayers for Ammonia Detection

Area of Science:

• Materials Science
• Nanotechnology
• Environmental Science

Background:

• Two-dimensional (2D) materials offer unique properties for atmospheric pollutant monitoring.
• Intelligent sensing applications benefit from the high surface area and distinct physical characteristics of 2D materials.

Purpose of the Study:

• To investigate the gas-sensing potential of hafnium nitride bromide (HfNBr) monolayers for ammonia (NH3) detection.
• To explore the impact of point defects on the sensing performance of HfNBr monolayers.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to study defect-induced changes.
• Nonequilibrium Green's Function (NEGF) method was utilized to analyze electronic transport properties.
• Adsorption energy, charge transfer, density of states, and current-voltage characteristics were computed.

Main Results:

• Point defects dramatically enhanced ammonia adsorption on HfNBr monolayers, increasing adsorption energy from -0.162 to -1.257 eV.
• Analysis revealed significant charge transfer and altered electronic structures upon ammonia adsorption.
• The NEGF method showed a remarkable change in apparent resistance, indicating high sensitivity.

Conclusions:

• Defective HfNBr monolayers exhibit excellent sensitivity and selectivity for ammonia detection.
• The findings highlight the potential of engineered HfNBr for practical atmospheric ammonia monitoring.
• This study underscores the importance of defect engineering in designing advanced 2D material-based gas sensors.