Theoretical study on the functionalized graphene nanostructures with carbendazim

Since the discovery of graphene in 2004 [1], due to their unique electronic, mechanical, and thermal properties is strongly affected by the adsorption of molecules making this material veryattractive for sensing application. Unfortunately, the poor solubility have hampered the future application of graphene in sensing of materials in aqueous solutions. By experimental treatment of graphene in an oxidizing environment, the oxygen-containing groups such as –COOH, −COOand −OH are introduced to the ends and surface of the sheets [2]. According to experimentaltreatment, our results may be useful for further studies in functionalization of graphene with acarboxyl group and construction of nanodevices and nanosensors for sensing electroactivematerials. Carbendazim (CBZ, methyl 2-benzimidazole carbamate) is a benzimidazole fungicide widely used to control black spot (a fungal disease of citrus, cereals and bean) in many countries. The environmental protection agency (EPA) allowed limited use of CBZ in citrus fruit until2009. Due to the high consumption of orange juice and cereals in the world and the high environmental impact that may result, the control of CBZ levels is extremely important [3, 4]. Within this work, we performed a DFT study on the interactions of a CBZ molecule, with thesurface of a functionalized graphene with carboxyl group (Gr-COOH), consequently adsorption energy, HOMO/LUMO energy gap, charge transfer and electronic properties in the adsorptionprocess were investigated. The full geometry optimizations and property calculations were performed with the quantum- ESPRESSO suite of codes [5]. The widely used generalized gradient approximation (GGA) with the exchange-correlation functional parameterized by Perdew, Burke and Ernzerhof (PBE) was adopted, using spin-polarized calculations [6].The Brillouin zone was sampled with 4 × 4 × 2Monkhorst-Pack k-points mesh, to ensure convergence. All of the proposed complexes are calculated in the same periodic supercell, with the same k-point sampling grid, the same DFT approach and used solvation model with water solvent, ensuring consistency between calculations. To study CBZ adsorption, the CBZ molecule are positioned in three configurations at the surface. In model A, B and C interaction of imin, amin and ester functional group with -COOH on graphene sheet was investigated, respectively. The adsorption energy and moredetailed information for considering configurations are listed in Table 1. According to the obtained information, adsorption energy of configuration A shows the strongest interaction between CBZ molecule and Gr-COOH sheet than other configurations