Contents lists available at ScienceDirect Chemical Physics Letters journal homepage: www.elsevier.com/locate/cplett Research paper A DFT study of defects in SnO monolayer and their interaction with O 2 molecule Aarti Shukla, N.K. Gaur Department of Physics, Barkatullah University, Bhopal 462026, India HIGHLIGHTS • The origin of magnetism by impurity defects in SnO monolayer is investigated by density functional theory. • Both the Sn and O vacancy reduce the band gap and shows semiconductor behavior. • The substitution of B and N demonstrates the ferromagnetic semiconductor nature of the SnO monolayer. • The vacancies significantly enhance the chemical activity towards O 2 molecule in the defective SnO monolayer. • The adsorption strength of the O 2 molecule may be beneficial for catalysis like an oxygen reduction reaction (ORR). ARTICLE INFO Keywords: First principles study Defects Ferromagnetic Semiconductor ABSTRACT In this study, we have employed the first-principles calculations to investigate the influence of various point defects such as vacancy and impurities in SnO monolayer (ML) through the electronic and magnetic properties. Our results demonstrate the magnitude of the formation energy decreases in the order of B > C > N, which may be influenced by the different electronegativities. All these defective systems, defects could induce some defect energy levels in the band gap and significantly enhance the adsorption strength for capture O 2 molecule. The analysis of adsorption energy of O 2 molecule and electronic properties reveal the strong interaction of free O 2 with the defective monolayer. These findings may provide useful information to understand the origin of magnetism in the SnO monolayer in the presence of defects. Moreover, our work may provide a useful way to use of SnO ML as a catalyst in oxygen reduction reaction and gas sensor devices. 1. Introduction Recently, two-dimensional (2D) materials have shown remarkable attention in many potential applications such as gas sensors, photo- catalyst, battery, optical and electronic devices due to their fascinating electronic and magnetic properties, thermophysical properties in- cluding high volume surface ratio [1–3]. Over the past decade, sig- nificant advances have been made in the synthesis of a variety of 2D nanomaterials, including graphene, metal chalcogenides and metal oxides, etc [2,4]. After the successful exfoliation of layered oxides such as manganese oxide [5], niobium oxide [6], titanium oxide [7], cobalt oxide [8] and tin oxide [5], the metal oxide-based materials have gained much interest in the various electronic, magnetic, spintronics and gas sensor devices [9]. Among metal oxide 2D materials, SnO is one of the promising candidates for the application in the field-effect transistor (FET), has gained interest in the family of metal oxides. 2D SnO has been suc- cessfully synthesized experimentally and exhibits native p-type con- ductivity and can be used for high-mobility p-channel thin-film in electronic applications [10]. It has the hole density range between 2- 3x10 -14 cm -2 and this range of hole density makes it applicable for multifunctional magnetic and electronic devices [11]. SnO ML is a nonmagnetic semiconductor with an indirect band gap of ∼ 2.7 eV [12]. An experimental study shows SnO nanosheet has been used as an anode material in Li-ion batteries [13]. In another study, it shows the highest selectivity towards NO 2 gas and hence can be used in a gas sensor de- vice for NO 2 gas detection [14]. In the presence of defects, the elec- tronic and magnetic properties of the bulk SnO have investigated the- oretically in its bulk phase[15]. The theoretical study shows the double- layer of SnO could be a promising candidate for photocatalytic water splitting for hydrogen evolution [16]. Moreover, the transition metal doped on SnO ML has been investigated where they have explored the origin of ferromagnetism in SnO ML[17,18]. In another study, the spin- dependent electronic and magnetic properties are studied in terms of the magnetic anisotropy of SnO in the effect of interfacial proximity of Fe 4 N substrates [19]. Moreover, in another theoretical study has shown SnO ML can be a promising candidate for spintronic and optoelectronic devices in the proximity of ferromagnetic CrN ML [20]. The theoretical and experimental studies have shown the electronic and magnetic properties of 2D materials can be modified by defect https://doi.org/10.1016/j.cplett.2020.137717 Received 23 February 2020; Received in revised form 11 June 2020; Accepted 12 June 2020 Chemical Physics Letters 754 (2020) 137717 Available online 30 June 2020 0009-2614/ © 2020 Published by Elsevier B.V. T