In our developing country, due to the increasing demand of technologies the emissions of different toxic gases as CO, CO2, NO, NO2 and NH3 from industries, vehicles or any other source is increasing day by day. The emission of theses gases in different concentration is a delibrate issue and it demands gas sensors. Adsorption of these gases are widely used for the sensing property. Two-dimensional (2D) materials create an extensive interest of researchers because of their novel electronic, optical, biocompatible, high charging capacity, large surface area, exclusive physical and chemical properties as compared to bulk materials. These characteristics are essentially important for different applications like electrodes and gas sensing. I have decided to work on the adsorption of different toxic gases in the gas sensing applications. In the group of 2D materials, borophene is a recent addition. . Borophene has metallic nature and low stability. To increase its stability, we made its interface with boron nitride that is pure insulator. Interface of borophene and boron nitride showed metallic behaviour and we utilized the properties of B/BN as a single material.Interface may increase the adsorption sites and improve adsorption energy that is good for gas sensing. Firstly, we select favourable adsorption sites with low formation energy and then adsorb different gases as CO, CO2, NO, NO2 and NH3 on the selected sites. All the gases showed chemisorption and make bond with the host material while CO2 showed physiosorption behaviour as shown in figure.
To calculate the adsorption energy i use the following formula
study showed the high adsorption energies than previous work. In addition to the study, the structural and the electronic properties of interface before and after adsorption of gases is also investigated. Total density of states (DOS) of pristine borophene and interface with adsorbed gases is shown in figure below. Our results show metallic behavior in both cases for all gases as inferred from the absence of a band gap that is good for gas sensing.
In case of interface, for all the gases we can see that these adsorbed gases induce change in DOS (broaden the peak) particularly in the valence band as compare to pristine borophene. Similarly, the transfer of charge between the atoms of gas and the interface and the transport properties of the selecetd gases for gas sensing applications is also calculated. To know the performance of the interface as a better sensor, non-equilibrium Green’s function (NEGF) method is done with computation for the properties related to transport. To conclude this, we have succefully made the interface of borophene and boron nitride to use its metallics properties as a single material in the gas sensing applications to avoid from the toxic gases that are hazardous for living organisms