Nitrogen doped compound defect in black phosphorene for enhanced gas sensing

Abstract

Point defects are widely recognized for their ability to fine-tune the surface reactivity and chemical selectivity of two-dimensional materials. This study delves into the surface adsorption of five environmentally detrimental gas molecules, namely NO2, SO2, CO, CO2, and NH3, on black phosphorene, employing first-principles calculations to explore the compound effect of two distinct point defects, specifically, P vacancy and N dopant. Our calculations unveil that the existence of dangling bonds in BP monolayers disrupts the N-O bond in the NO2 molecule, leading to an increase in adsorption energies to -5.74 eV and -4.40 eV. Interestingly, the monolayer with compound defect demonstrates promising results for detecting SO2 gas molecules but exhibits a decrease in adsorption energy by 44% and 76% when only one type of defect is present. In contrast, for CO, CO2, and NH3 molecules, insignificant changes near the Fermi level suggests that both systems, the one with the compound defect and those with a single defect, remain entirely insensitive. This nontrivial and distinctive study of a BP gas sensor incorporating compound point defect could provide ample insights into revealing its sensitivity and reliability in detecting environmentally harmful, toxic gases.