Graphene oxide/bismuth oxybromide composite photocatalysts to combat NOx pollution in air Paransa Alimard 1,2 , Adam Clancey 3 , Andreas Kafizas 1,4 1 Imperial College London, The Department of Chemistry, Molecular Science Research Hub, White City Campus, 82 Wood Lane, London, W12 0BZ, U.K. 2 Grantham Institute, Exhibition Road, South Kensington, London, SW7 2AZ, U.K. 3 University College London, The Department of Chemistry, Gordon Street, London, WC1E 0AJ, U.K. 4 London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, U.K. NOx, consisting of NO 2 and NO, is considered a prominent air pollutant originating from anthropogenic activities such as the combustion of fossil fuels and vehicular emissions. Exposure to high levels of NOx is known to have severe adverse health impacts and may potentially lead to increased mortality rates. In addition to its negative effects on human health, NOx also poses significant threats to the environment and plants. Notably, certain metropolitan areas, such as London, have surpassed the prescribed safety limits for NOx levels, indicating a critical need to address this issue [1] . Among the photocatalysts studied, TiO 2 is widely recognized for its ability to reduce atmospheric NOx concentrations. It has been shown to effectively degrade NOx at room temperature and atmospheric pressure, making it a promising candidate for this application [2] . The wide bandgap of TiO 2 has impeded its performance, thereby limiting its capacity to harness a small proportion (approximately 4%) of the solar spectrum. Conversely, BiOBr has emerged as a favourable substitute for TiO 2 , owing to its narrow bandgap, visible light absorption, low toxicity, and photocatalytic activity, thereby drawing significant attention [3] . Numerous researchers have focused their efforts on the synthesis of composites by integrating graphene with various photocatalysts [4] . Several reports suggest that modifying BiOBr with graphene oxide can improve its photocatalytic activity [5]. In this study, a nanocomposite consisting of two-dimensional nanosheets was synthesised employing a solvothermal method. X-ray diffraction (XRD), Raman spectroscopy (Raman), high-resolution scanning electron microscopy (HRSEM), UV-vis diffuse reflectance spectra (DRS), and a chemiluminescence NOx analyser were used to characterise the produced photocatalyst. The obtained sample’sphotocatalytic abilities for NO elimination at room temperature with a 1 ppm NOconcentrationunder UV lamp (352 nm) irradiation were assessed. Under UV lamp illumination, the photocatalyst oxidises 17.75% of NO, which is superior to the photocatalytic activity of BiOBr and graphene oxide under the same circumstances. Hence, it is possible to argue that the composite’s graphene inclusion enhanced the photocatalytic activity of BiOBr. This photocatalyst may be a potential candidate for NO removal employing visible light since it performs better under visible light than a UV lamp. References 1. R. Rai, M. Rajput, M. Agrawal, S. B. Agrawal, J. Sci. Res. 55 (2011) 77.
2. Q. Wu, R. Krol, J. Am. Chem. Soc. 134 (2012) 9369. 3. S.R. Kim, W.K. Jo, J. Hazard. Mater. 380 (2019) 120866. 4. P. Avouris, C. Dimitrakopoulos, Mater. Today, 15 (2012) 86. 5. X. Zhang, X. Chang, M.A. Gondal, B. Zhang, Appl. Surf. Sci. 258 (2012) 7826.
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