Density Functional Theory Study on Sensing and Dielectric Properties of Arsenic Trisulfide Nanosheets for Detecting Volatile Organic Compounds

We performed first-principles calculations based on the density functional theory (DFT) to study the sensing and static dielectric properties (within a weak field regime) of arsenic trisulfide (As2S3) nanosheets toward selected volatile organic compounds (VOCs) such as methanal, ethanal, and propanal. Our rigorous simulations reported on the VOCs adsorption on pristine, vacancy-induced, and heteroatom substituted As2S3 sheets, and we further studied the corresponding dielectric constants to investigate the exotic sensing behavior. We found that certain vacancy defects and heteroatom substitution not only improved the binding energies of VOCs but also resulted in significant changes in the dielectric constants before and after the adsorption. Measurable changes in the electronic properties calculated through the density of states and band structure calculations of pristine and defective As2S3 sheets upon the exposure of VOCs reinforced the efficient sensing characteristics of the As2S3. Furthermore, we used statistical thermodynamic analysis to investigate the VOCs sensing behavior under various pressure and temperature conditions. We strongly believe that our findings can simplify the understanding of the complex sensing mechanism and further help the synthesis of As2S3-based nanosensors toward VOCs.