Theoretical Study of 3d VIII Atom-Decorated γ-Graphyne for Adsorbing and Detecting Heptafluoroisobutyronitrile

Recently, Heptafluoroisobutyronitrile (C4F7N) has received widespread attention in replacing one of the most greenhouse-insulating gas, SF6. However, gas leakage is incredibly harmful to the health of operational personnel and the security of industry production, and developing C4F7N detection technology is of great necessity. In this work, the adsorption properties, as well as the sensing performance of C4F7N on 3d VIII atom-decorated γ-graphyne (γ-GY), were theoretically discussed. The adsorption structures, adsorption energies, electron transfer, adsorption distance, electron distribution, and electronic properties were compared. The results show that the introduction of Fe and Co atom enhance the chemisorption of C4F7N, and the adsorption of C4F7N brings the maximum electron redistribution of Fe/γ-GY among three TM/γ-GY. Only the adsorption on Fe/γ-GY leads to the vanishing of the magnetic moment and creates a band gap. For three different modifications of γ-GY, the chemical interactions are highly related to the overlapping of transition metal 3d and N 2p orbitals in the density of states. The adsorption on Co/γ-GY causes the maximum change in work function from 5.06 eV to 5.26 eV. In addition, based on the band structure, work function, and desorption properties, the sensing properties of 3d VIII atom-decorated γ-GY were evaluated in order to promote the experimental exploration and development of high-performance C4F7N gas sensors.