2-D Be2C as Multitime Reversible Environmental Oxygen- and Nitrogen-Containing Gases Sensor Material Under First Principle Investigations

A combined density functional theory and nonequilibrium Green's function (DFT-NEGF) approach has been conducted to examine the potential of monolayer Be2C nanosheet as a promising sensor for various environmentally toxic/nontoxic nitrogen- and oxygen-containing multigases (NCGs and OCGs). A total of eight gases comprising four OCGs (O2, CO, CO2, and H2O) and four NCGs (NO, NO2, N2O, and NH3) are investigated on the surface of monolayer Be2C to identify its gas sensing potential. The nontoxic O2, CO2, and H2O are also included in the study considering their obvious presence in the environment. Our investigation suggests that at room temperature, larger adsorption energy of NO, NH3, and O2 gas molecules on the surface of Be2C reflects a more significant recovery time as 1016, 105, and 1012 s, respectively. The positive higher adsorption energy of NO2 gas molecules as 0.91 eV adsorbed on the Be2C nanosheet at room temperature results in a very short recovery time of 10−29 s. The adsorption energy of the NO2 gas molecule is positive, making it unsuitable for gas sensors. In all cases, notable variation is observed in electronic and adsorption properties, charge transfer, recovery time, work function, and transport characteristics of OCGs and NCGs on Be2C surface. OCGs and NCGs show electron acceptor nature during interaction with Be2C nanosheet. The electronic transport of Be2C sheet shows its highly selective and sensitive nature toward OCGs and NCGs. Overall, monolayer Be2C reveals as an excellent multitime reversible multigas sensor material for four gases, viz. CO, CO2, H2O, and N2O with their significantly low recovery time, whereas it appears to be one-time disposable sensor material for O2, NO, and NH3 gases with higher adsorption energy and relatively long recovery time.