A First Principle Study on Sensing Properties of Twisted Nanographenes Towards Phosgene, Thiophosgene and Formaldehyde

Abstract

The harmful chemicals like chemical warfare agents (CWAs) and toxic industrial chemicals (TICs) are extremely pernicious to the climate and living systems. The efficient detection and removal of these noxious chemicals in limited time span is essential for the human health and environmental security. Twisted nanographenes have great applications in the fields of energy storage and optoelectronics, but their applications as sensors are rarely described. Therefore, we have explored theoretically the sensitivity and selectivity of twisted nanographenes C32H16, C64H32 towards the harmful chemicals like phosgene, thiophosgene and formaldehyde. Here, we elaborate the phenomena of adsorption of the selected toxic chemicals on twisted nanographenes' surface within the framework of density functional theory (DFT). Adsorption interpretation is depending upon the optimized geometries, adsorption energies, NBO (natural bond orbital) charge transfer, frontier molecular orbital (FMO), absorption (UV-Vis), NCI (non-covalent interaction) and QTAIM (quantum theory of atoms in molecules) analyses. Results of interaction energies reveal the physiosorption of the toxic chemicals on the twisted nanographenes surface, which mainly arise due to the non-covalent interactions. The non-covalent nature of adsorption of toxic chemicals on twisted nanographenes surface is also ascribed by the NCI and QTAIM analyses. Most favorable adsorptions of the selected toxic chemicals occur at the edges of the distorted moiety (central ring). The average band gap changes (%Eg) and %sensitivity is quantitatively determined by the molecular orbital analysis, to evaluate the sensitivity of twisted nanographenes. Among the selected chemicals, the sensing of thiophosgene (ThP) is prominent on the twisted nanographenes surface, having interaction energies of -8.19 and -12.14 kcal mol-1 (in case of C32H16 and C64H32 tNGs), respectively. Therefore, it is concluded that twisted nanographenes can be applied as a potential sensing agent for the detection of toxic chemicals, especially thiophosgene. Thisx research will help the experimentalists to devise novel sensors based on twisted nanographenes.