Modeling Enhanced Adsorption of Explosive Molecules on a Hydroxylated Graphene Pore

Ronald Scott Holt,Thomas R Rybolt

doi:10.4236/graphene.2019.81001

Abstract

The possibility of a graphene bilayer nanosensor for the detection of explosive molecules was modeled using computational chemistry. A pore was designed on a graphene bilayer structure with three strategically placed perimeter hydroxyl (OH) groups built around the edge of an indented, two-dimensional hexagonal pore. This hydroxylated pore and models of various explosive molecules were optimized using MM2 molecular mechanics parameters. Values were calculated for the molecule-surface interaction energy (binding energy), E, for 22 explosive molecules on a flat graphene bilayer and on the specially designed hydroxylated pore within the bilayer. The molecule-surface binding energy for trinitrotoluene (TNT) increased from 17.9 kcal/mol on the flat graphene bilayer to 42.3 kcal/mol on the hydroxylated pore. Due to the common functionality of nitro groups that exist on many explosive molecules, the other explosive molecules studied gave similar enhancements based on the specific hydrogen bonding interactions formed within the pore. Each of the 22 explosive adsorbate molecules showed increased molecule-surface interaction on the bilayer hydroxylated pore as compared to the flat bilayer. For the 22 molecules, the average E for the flat graphite surface was 15.8 kcal/mol and for the hydroxylated pore E was 33.8 kcal/mol. An enhancement of adsorption should make a detection device more sensitive. Nanosensors based on a modified graphene surface may be useful for detecting extremely low concentrations of explosive molecules or explosive signature molecules.

Highlights

The unique and unusual structural and electrical properties of graphene have led to the development of graphene-based chemical sensors and biosensors of varied structures and fabrication methods
Due to the common functionality of nitro groups that exist on many explosive molecules, the other explosive molecules studied gave similar enhancements based on the specific hydrogen bonding interactions formed within the pore
The enhancement of molecule-surface interaction was provided by the construction of a model graphene bilayer hydroxylated pore

Summary

Introduction

The unique and unusual structural and electrical properties of graphene have led to the development of graphene-based chemical sensors and biosensors of varied structures and fabrication methods. Resistivity changes on graphene-based sensors have been used for gas phase sensing at low levels. Graphene-based electronic devices that can act as sensors for specific molecules; or for environmental properties such as temperature, light, and moisture; or more generally as electronic noses have been of interest in recent years [1]. Graphene nanostructures have been integrated into field-effect transistor (FET) and chemiresistive devices to obtain sensing properties [2]. One example of the advantage of surface modification has been the use of an ozone treatment to modify a graphene surface. This modification resulted in going from a pristine graphene sensor with a detection limit above 10 ppm for NO2 to a sensor with a limit of 1.3 ppb [5]

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