Sensing Ammonia (NH3) By Graphyne and Graphyne Oxide

According to previous researches about graphyne and graphene oxide derivatives toward sensors applications, in this study, we investigated the interaction of NH3 on graphyne (GY) and graphyne oxide contains an oxygen (GYO) or two oxygen atoms (GYO2) by density functional theory (DFT) calculations. We examined the effect of introduction of oxygen atom in GY structure on the adsorption of NH3. NH3 affects on human health, adversely and pollutes the environment. Thus, some effective methods should be designed in order to detect and control NH3 molecule (by capturing and separating technologies). In 1987, various types of GY were suggested by Baughman and co-workers and the most stable of them is γ-GY that was investigated in this work. We put NH3 in different sites of GY, GYO and GYO2 from various orientations and distances respect to carbon sheets and the most stable states were determined. Results show that insertion of one or two oxygen atoms forms very stable oxides with much larger binding energies than graphene. Oxygen trends to join to sp-hybridized carbon atoms and forms carbonyl and epoxy groups that carbonyl is more stable. The highest adsorption energies (Eads) of NH3 on GY, GYO and GYO2 are -0.270, -0.382 and -0.294 eV, respectively, that show physisorption mechanisms. So, one can be said that insertion of the first O atom increases the adsorption energy, while insertion of the second O atom has inverse treatment. Altering the oxygen coverage through changing the number of oxygen atom in a supercell can tune the electronic properties and decreases band gap value of GY.