Defect-Engineering of 2D Dichalcogenide VSe2 to Enhance Ammonia Sensing: Acumens from DFT Calculations

Abstract

Opportune sensing of ammonia (NH3) gas is industrially important for avoiding hazards. With the advent of nanostructured 2D materials, it is felt vital to miniaturize the detector architecture so as to attain more and more efficacy with simultaneous cost reduction. Adaptation of layered transition metal dichalcogenide as the host may be a potential answer to such challenges. The current study presents a theoretical in-depth analysis regarding improvement in efficient detection of NH3 using layered vanadium di-selenide (VSe2) with the introduction of point defects. The poor affinity between VSe2 and NH3 forbids the use of the former in the nano-sensing device's fabrications. The adsorption and electronic properties of VSe2 nanomaterials can be tuned with defect induction, which would modulate the sensing properties. The introduction of Se vacancy to pristine VSe2 was found to cause about an eight-fold increase (from -012 eV to -0.97 eV) in adsorption energy. A charge transfer from the N 2p orbital of NH3 to the V 3d orbital of VSe2 has been observed to cause appreciable NH3 detection by VSe2. In addition to that, the stability of the best-defected system has been confirmed through molecular dynamics simulation, and the possibility of repeated usability has been analyzed for calculating recovery time. Our theoretical results clearly indicate that Se-vacant layered VSe2 can be an efficient NH3 sensor if practically produced in the future. The presented results will thus potentially be useful for experimentalists in designing and developing VSe2-based NH3 sensors.