Ab-Initio Spectroscopic Characterization of Melem-Based Graphitic Carbon Nitride Polymorphs

Light-Induced Transformation of Virus-Like Particles on TiO2

Titanium dioxide (TiO2) shows significant potential as a self-cleaning material to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and prevent virus transmission. This study provides insights into the impact of UV-A light on the photocatalytic inactivation of adsorbed SARS-CoV-2 virus-like particles (VLPs) on a TiO2 surface at the molecular and atomic levels. X-ray photoelectron spectroscopy, combined with density functional theory calculations, reveals that spike proteins can adsorb on TiO2 predominantly via their amine and amide functional groups in their amino acids blocks. We employ atomic force microscopy and grazing-incidence small-angle X-ray scattering (GISAXS) to investigate the molecular-scale morphological changes during the inactivation of VLPs on TiO2 under light irradiation. Notably, in situ measurements reveal photoinduced morphological changes of VLPs, resulting in increased particle diameters. These results suggest that the denaturation of structural proteins induced by UV irradiation and oxidation of the virus structure through photocatalytic reactions can take place on the TiO2 surface. The in situ GISAXS measurements under an N2 atmosphere reveal that the virus morphology remains intact under UV light. This provides evidence that the presence of both oxygen and UV light is necessary to initiate photocatalytic reactions on the surface and subsequently inactivate the adsorbed viruses. The chemical insights into the virus inactivation process obtained in this study contribute significantly to the development of solid materials for the inactivation of enveloped viruses.

Emerging Two-Dimensional Materials: Inspiring Nanotechnologies for Smart Energy Management

Two-dimensional (2D) materials are a class of materials that can be reduced to a thickness of a few layers, exhibiting peculiar and innovative properties relative to their three-dimensional solid counterparts [...].

Adsorption and Inactivation of SARS-CoV-2 on the Surface of Anatase TiO2(101)

We investigated the adsorption of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), the virus responsible for the current pandemic, on the surface of the model catalyst TiO₂(101) using atomic force microscopy, transmission electron microscopy, fluorescence microscopy, and X-ray photoelectron spectroscopy, accompanied by density functional theory calculations. Three different methods were employed to inactivate the virus after it was loaded on the surface of TiO₂(101): (i) ethanol, (ii) thermal, and (iii) UV treatments. Microscopic studies demonstrate that the denatured spike proteins and other proteins in the virus structure readsorb on the surface of TiO₂ under thermal and UV treatments. The interaction of the virus with the surface of TiO₂ was different for the thermally and UV treated samples compared to the sample inactivated via ethanol treatment. AFM and TEM results on the UV-treated sample suggested that the adsorbed viral particles undergo damage and photocatalytic oxidation at the surface of TiO₂(101) which can affect the structural proteins of SARS-CoV-2 and denature the spike proteins in 30 min. The role of Pd nanoparticles (NPs) was investigated in the interaction between SARS-CoV-2 and TiO₂(101). The presence of Pd NPs enhanced the adsorption of the virus due to the possible interaction of the spike protein with the NPs. This study is the first investigation of the interaction of SARS-CoV-2 with the surface of single crystalline TiO₂(101) as a potential candidate for virus deactivation applications. Clarification of the interaction of the virus with the surface of semiconductor oxides will aid in obtaining a deeper understanding of the chemical processes involved in photoinactivation of microorganisms, which is important for the design of effective photocatalysts for air purification and self-cleaning materials.

Radical defects modulate the photocatalytic response in 2D-graphitic carbon nitride

Graphitic carbon nitride (gCN) is an important heterogeneous metal-free catalytic material. Thermally induced post-synthetic modifications, such as amorphization and/or reduction, were recently used to enhance the photocatalytic response of these materials for certain classes of organic transformations, with structural defects possibly playing an important role. The knowledge of how these surface modifications modulate the photocatalytic response of gCN is therefore not only interesting from a fundamental point of view, but also necessary for the development and/or tuning of metal-free gCN systems with superior photo-catalytic properties. Herein, employing density functional theory calculations and combining both the periodic and molecular approaches, in conjunction with experimental EPR measurements, we demonstrate that different structural defects on the gCN surface generate distinctive radical defect states localized within the electronic bandgap, with only those correlated with amorphous and reduced gCN structures being photo-active. To this end, we (i) model defective gCN surfaces containing radical defect states; (ii) assess the interactions of these defects with the radical precursors involved in the photo-driven alkylation of electron-rich aromatic compounds (namely perfluoroalkyl iodides); and (iii) describe the photo-chemical processes triggering the initial step of that reaction at the gCN surface. We provide a coherent structure/photo-catalytic property relationship on defective gCN surfaces, elaborating how only specific defect types act as binding sites for the perfluoroalkyl iodide reagent and can favor a photo-induced charge transfer from the gCN surface to the molecule, thus triggering the perfluoroalkylation reaction.

The nature of radical defects governs the photocatalytic activity of graphitic carbon nitride.

Nanobeams with Internal Discontinuities: A Local/Nonlocal Approach

The aim of the present work is to extend the two-phase local/nonlocal stress-driven integral model (SDM) to the case of nanobeams with internal discontinuities: as a matter of fact, the original formulation avoids the presence of any discontinuities. Consequently, here, for the first time, the problem of an internal discontinuity is addressed by using a convex combination of both local and nonlocal phases of the model by introducing a mixture parameter. The novel formulation here proposed was validated by considering six case studies involving different uncracked nanobeams by varying the constrains and the loading configurations, and the effect of nonlocality on the displacement field is discussed. Moreover, a centrally-cracked nanobeam, subjected to concentrated forces at the crack half-length, was studied. The size-dependent Mode I fracture behaviour of the cracked nanobeam was analysed in terms of crack opening displacement, energy release rate, and stress intensity factor, showing the strong dependency of the above fracture properties on both dimensionless characteristic length and mixture parameter values.