Kinetic Analysis of the Reduction of 4‑Nitrophenol Catalyzed by CeO₂ Nanorods-Supported CuNi Nanoparticles

Cu_<i>x</i>Ni_{100–<i>x</i>} (<i>x</i> = 0, 20, 40, 60, 80, and 100) nanoparticles were uniformly grown on the surface of CeO₂ by the liquid impregnation method. The as-prepared nanocomposite abbreviated Cu_<i>x</i>Ni_{100–<i>x</i>}–CeO₂ was characterized by various techniques including, X-ray powder diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface area analyzer, and transmission electron microscopy. The catalytic activity of Cu_<i>x</i>Ni_{100–<i>x</i>}–CeO₂ nanocomposites was investigated in 4-nitrophenol (4-NP) reduction reaction. Among the synthesized nanocomposites, Cu₆₀Ni₄₀–CeO₂ exhibited the best catalytic activity (rate constant as 0.1654 s^–1) with high recyclability for five consecutive runs. The mechanism of the reduction was studied, and the adsorption equilibrium constant of 4-NP (<i>K</i>_4‑NP) and borohydride (<i>K</i>_BH₄^–) was calculated by using the Longmuir–Hinshelwood model. The energy of activation (<i>E</i>_a) and thermodynamic parameters such as activation enthalpy (Δ<i>H</i>^⧧), entropy (Δ<i>S</i>^⧧), and Gibbs free energy (Δ<i>G</i>^⧧) have also been determined

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