molecules Article Comparative Study of Phosgene Gas Sensing Using Carbon and Boron Nitride Nanomaterials—A DFT Approach Emmanuel Obroni Kweitsu 1 , Stephen Kanga Armoo 2 , Kwabena Kan-Dapaah 3 , Eric Kwabena Kyeh Abavare 4 , David Dodoo-Arhin 1 and Abu Yaya 1, *   Citation: Kweitsu, E.O.; Armoo, S.K.; Kan-Dapaah, K.; Abavare, E.K.K.; Dodoo-Arhin, D.; Yaya, A. Comparative Study of Phosgene Gas Sensing Using Carbon and Boron Nitride Nanomaterials—A DFT Approach. Molecules 2021, 26, 120. https://doi.org/10.3390/ molecules26010120 Received: 30 November 2020 Accepted: 24 December 2020 Published: 29 December 2020 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. Copyright: © 2020 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Materials Science and Engineering, School of Engineering Sciences, CBAS, University of Ghana, Legon P.O. Box LG 77, Ghana; ekweitsu@gmail.com (E.O.K.); ddodoo-arhin@ug.edu.gh (D.D.-A.) 2 Department of Computer Engineering, School of Engineering Sciences, CBAS, University of Ghana, Legon P.O. Box LG 77, Ghana; SArmoo@ug.edu.gh 3 Department of Biomedical Engineering, School of Engineering Sciences, CBAS, University of Ghana, Legon P.O. Box LG 77, Ghana; KKan-Dapaah@ug.edu.gh 4 Department of Physics, Ghana Private Mail Bag, Kwame Nkrumah University of Science and Technology, Kumasi 00233, Ghana; EKKAbavare.cos@knust.edu.gh * Correspondence: ayaya@ug.edu.gh; Tel.: +233-559-278-551 Abstract: Phosgene (COCl 2 ), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of these nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl 2 . The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl 2 molecule adsorbed spontaneously on the Fullerene or nanocages and endothermically on the pristine zigzag nanotubes. Using the magnitude of the bandgap modulation, the order of suitability of the different nanomaterials was established as follows: PBN60 (0.19%) < PC70 (1.39%) < PC60 (1.77%) < PBNNT (27.64%) < PCNT (65.29%) < PBN70 (134.12%). Since the desired criterion for the design of an electronic device is increased conductivity after adsorption due to the resulting low power consumption, PC60 was found to be most suitable because of its power consumption as it had the largest decrease of 1.77% of the bandgap. Keywords: phosgene; boron nitride; carbon nanotube; DFT; LDA 1. Introduction Phosgene, is a valuable industrial organic compound, with a chemical formula COCl 2. It was first obtained in 1812 by John Humphrey Davy when he exposed a mixture of chlorine and carbon monoxide to sunlight [1]. At room temperature, it appears as a colourless gas and at low concentrations, smells like newly cut musty hay. It is a highly toxic substance that can lead to pathophysiological conditions such as blurred vision, irritable eyes, throat, and lungs, asphyxia, and even death when inhaled at low concentrations [2]. These harmful properties of COCl 2 can, and in fact, has been exploited as a chemical weapon agent. One notable instance is when the Germans used it as a choking agent during World War I in 1915 causing about 80% of all chemical-related casualties at the time [3]. Today, the threat of this insidious property can be related to potential industrial accidents or leakages as well as terrorist attacks on industrial plants, stocks, or transports. Therefore, there is a need for the development of detection techniques for public safety in an industrial environment or against terrorist attacks. Conventional methods based Molecules 2021, 26, 120. https://doi.org/10.3390/molecules26010120 https://www.mdpi.com/journal/molecules