Selective detection of cyanogen halides by BN nanocluster: a DFT study

E Vessally,A Hosseinian,B Massuomi,F Behmagham,K Nejati

doi:10.1007/s00894-017-3312-1

E Vessally, A Hosseinian + Show 3 more

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https://doi.org/10.1007/s00894-017-3312-1

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Abstract

The electronic sensitivity and adsorption behavior toward cyanogen halides (X–CN; X = F, Cl, and Br) of a B12N12 nanocluster were investigated by means of density functional theory calculations. The X-head of these molecules was predicted to interact weakly with the BN cluster because of the positive σ-hole on the electronic potential surface of halogens. The X–CN molecules interact somewhat strongly with the boron atoms of the cluster via the N-head, which is accompanied by a large charge transfer from the X–CN to the cluster. The change in enthalpy upon the adsorption process (at room temperature and 1 atm) is about −19.2, −23.4, and −30.5 kJ mol−1 for X = F, Cl, and Br, respectively. The LUMO level of the BN cluster is largely stabilized after the adsorption process, and the HOMO–LUMO gap is significantly decreased. Thus, the electrical conductivity of the cluster is increased, and an electrical signal is generated that can help to detect these molecules. By increasing the atomic number of X, the signal will increase, which makes the sensor selective for cyanogen halides. Also, it was indicated that the B12N12 nanocluster benefits from a short recovery time as a sensor.

Highlights

Cyanogen halides (X–CN, X = halogen) are colorless, chemically reactive, lachrymatory, and volatile compounds with a linear structure [1]
Natural bond orbitals (NBO), molecular electrostatic potential (MEP) and density of states (DOS) analyses, geometry optimizations, and energy predictions were performed on a B12N12 nanocluster and different X-CN/B12N12 complexes at B3LYP level of theory with 6-31G (d) basis set as implemented in the GAMESS suite of programs [35]
Frontier molecular orbital analysis shows that, in accordance with the energy change, the LUMO level is shifted from the surface of the Boron nitride (BN) cage to the surface of Br–CN (Fig. 5). These findings indicate that the presence of X–CN molecules will boost the electrical conductivity of the B12N12 nanocage, which, by increasing the atomic number of X atoms, increases the electrical conductivity more

Summary

Introduction

Cyanogen halides (X–CN, X = halogen) are colorless, chemically reactive, lachrymatory (tear-producing), and volatile compounds with a linear structure [1]. They are highly poisonous agents, and symptoms of exposure may include paralysis, vomiting, drowsiness, coughing, convulsion, throat confusion, edema, and death [1, 2]. Previous methods suggested and investigated include spectrophotometric, electrochemical, and gas chromatographic approaches [3–5]. Most of these procedures need complicated instruments and are expensive. With the advent of nanotechnology, gas sensor development has accelerated due to the high adsorption capacity, high surface/volume ratio and unique electronic sensitivity of nanostructures [6, 7]. Many studies have focused on the fullerene-like BN nanoclusters, nanosheets and nanotubes as gas sensors [19–24]

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