Adsorption properties of Cr modified GaN monolayer for H2, CO, C2H2 and C2H4

Abstract

Abstract In this paper, we explored the adsorption behavior of four kinds of characteristic gases dissolved in oil on Cr doped GaN monolayer. The results show that the Cr-GaN monolayer exhibits satisfactory adsorption performance for H2, CO, C2H4 and C2H2 molecules. The adsorption energies of H2 (−0.326\xa0eV), CO (−0.7\xa0eV), C2H4 (−0.893\xa0eV) and C2H2 (−0.751\xa0eV) manifest the adsorptions can occur spontaneously. According to Hirshfeld charge analysis, Cr-GaN monolayer as an electron donor loses electrons of 0.124, 0.287, 0.243 and 0.244 e when interacting with H2, CO, C2H4 and C2H2. The dramatic changes of molecules can be observed after adsorption, indicating the strong interaction between molecules and Gr-GaN monolayer. Besides, the presence of significant overlaps between Cr atom and those molecules in the PDOS analysis verify the interaction is caused by chemisorption. The calculation of the band gap based on the frontier orbital theory shows that there is a significant difference in the conductivity of Cr-GaN before and after adsorption. Therefore, Cr-GaN based material could be used as resistance transducer to detect CO and C2H2. This preliminary research provides a supplement to the study of the physicochemical properties of the transition metal modified GaN monolayer, and provides a first look of the potential application of the Cr-GaN monolayer in the field of gas sensors.