Unraveling the Intrinsic Biocidal Activity of the SiO₂–Ag Composite against SARS-CoV-2: A Joint Experimental and Theoretical Study

The COVID-19 pandemic has emerged as an unprecedented global healthcare emergency, demanding the urgent development of effective materials to inactivate the SARS-CoV-2 virus. This research was planned to disclose the remarkable biocidal activity of SiO 2 –Ag composites incorporated into low-density polyethylene. For this purpose, a joint experimental and theoretical [based on first-principles calculations at the density functional theory (DFT) level] study is performed. Biological assays showed that this material eliminates Staphylococcus aureus and SARS-CoV-2 virus in just 2 min. Here, we investigate a previously unexplored process that we postulate may occur along the O 2 and H 2 O adsorption and activation processes of pure and defective SiO 2 –Ag surfaces for the generation of reactive oxygen species (ROS). The obtained results help us to predict the nature of ROS: superoxide anion radicals, • O 2 –, hydroxyl radicals, • OH, and hydroperoxyl radicals, • HO 2, that destroy and degrade the structure of the SARS-COV-2 virus. This is consistent with the DFT studies, where the energetic, electronic, and magnetic properties of the intermediates show a feasible formation of ROS. Present findings are expected to provide new insights into the relationship among the structure, property, and biocidal activity of semiconductor/metal SiO 2 –Ag composites.