Investigation of the electronic and structural properties of graphyne oxide toward CO, CO_2 and NH_3 adsorption: A DFT and MD study

摘要

Graphyne (GY), a 2D carbon allotrope, has excellent electronic properties. Similar to other carbon structure, changing in some of the electronic and structural properties causes to promote its practical applications. Functionalization is one of the best methods for this objective. In this work, insertion of one to four oxygen atoms in various sites of the GY by DFT-D and molecular dynamic (MD) calculations were performed to study the corresponding electronic and structural properties of the oxidized graphyne. Then, adsorption of CO, CO2 and NH3 was considered. Results show that insertion of one to four 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. Also, insertion of the first O atom increases adsorption energies and decreases band gap values, 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. For three adsorbed molecules, the best site and orientation for adsorption were determined and discussed. It was seen that adsorption to GYO is stronger than GY and GYO(2).