Theoretical Study on Defective g-GaN for CO2 Adsorption

Abstract

Carbon neutrality is one of ultimate goals of global population. The detection of CO2, now, is a research hotspot, and two-dimensional materials are undoubtedly play an important role. In this paper, the first-principles approach based on density functional theory was used to study the adsorption behavior of CO2 on intrinsic and defective g-GaN. The results are as follows. The adsorption energy is relatively bigger, the band gap and the structures of g-GaN and CO2 have no obvious changes when CO2 is adsorbed on the intrinsic g-GaN. It indicates that intrinsic g-GaN is inert to CO2. Defective g-GaN still maintains a planar structure, but g-GaN are transformed from semiconductors to half-metal and metals after the introduction of Ga and N single vacancies, respectively. The CO2 adsorption energy and adsorption distance are reduced, the structure of defective g-GaN is obviously deformed when CO2 is adsorbed on defective g-GaN. It indicates that the adsorption between g-GaN and CO2 is stronger. CO2 is physically adsorbed on these three structures from the perspective of charge exchange which is good for desorption. Defective g-GaN still remain half-metallic and metallic properties after CO2 is adsorbed on it. From the adsorption energy, the introduction of Ga vacancy enhances the detection ability of g-GaN for CO2, and it is better than N vacancy. This provides theoretical support for g-GaN materials as a nanoscale gas sensor materials.