Two-Dimensional MXene as a Promising Adsorbent for Trihalomethanes Removal: A Density-Functional Theory Study.

This groundbreaking research delves into the intricate molecular interactions between MXene and trihalomethanes (THs) through a comprehensive theoretical study employing density-functional theory (DFT). Trihalomethanes are common carcinogenic chlorination byproducts found in water sanitation systems. This study focuses on a pristine MXene [Mn+1·Xn] monolayer and its various terminal [Tx] functional groups [Mn+1·XnTx], strategically placed on the surface for enhanced performance. Our investigation involves a detailed analysis of the adsorption energies of THs on different MXene types, with the MXene-Cl layer emerging as the most compatible variant. This specific MXene-Cl layer exhibits remarkable properties, including a total dipole moment (TDM) of 12.443 Debye and a bandgap of 0.570 eV, achieved through meticulous geometry optimization and computational techniques. Notably, THs such as trichloromethane (CHCl3), bromide-chloromethane (CHBrCl2), and dibromochloromethane (CHBr2Cl) demonstrate the highest TDM values, indicating substantial changes in electronic and optical parameters, with TDM values of 16.363, 15.998, and 16.017 Debye, respectively. These findings highlight the potential of the MXene-Cl layer as an effective adsorbent and detector for CHF3, CHClF2, CHCl3, CHBrCl2, and CHBr2Cl. Additionally, we observe a proportional increase in the TDM and bandgap energy, indicative of conductivity, for various termination atom combinations, such as Mxene-O-OH, Mxene-O-F, Mxene-O-Cl, Mxene-OH-F, Mxene-F-Cl, and Mxene-OH-Cl, with bandgap energies measured at 0.734, 0.940, 1.120, 0.835, and 0.927 eV, respectively. Utilizing DFT, we elucidate the adsorption energies of THs on different MXene surfaces. Our results conclusively demonstrate the significant influence of the termination atom nature and quantity on MXene's primitive TDM value. This research contributes to our understanding of MXene-THs interactions, offering promising avenues for the development of efficient adsorbents and detectors for THs. Ultimately, these advancements hold the potential to revolutionize water sanitation practices and enhance environmental safety.

DFT and QSAR studies of PTFE/ZnO/SiO2 nanocomposite.

Polytetrafluoroethylene (PTFE) is one of the most significant fluoropolymers, and one of the most recent initiatives is to increase its performance by using metal oxides (MOs). Consequently, the surface modifications of PTFE with two metal oxides (MOs), SiO2 and ZnO, individually and as a mixture of the two MOs, were modeled using density functional theory (DFT). The B3LYPL/LANL2DZ model was used in the studies conducted to follow up the changes in electronic properties. The total dipole moment (TDM) and HOMO/LUMO band gap energy (∆E) of PTFE, which were 0.000 Debye and 8.517 eV respectively, were enhanced to 13.008 Debye and 0.690 eV in the case of PTFE/4ZnO/4SiO2. Moreover, with increasing nano filler (PTFE/8ZnO/8SiO2), TDM changed to 10.605 Debye and ∆E decreased to 0.273 eV leading to further improvement in the electronic properties. The molecular electrostatic potential (MESP) and quantitative structure activity relationship (QSAR) studies revealed that surface modification of PTFE with ZnO and SiO2 increased its electrical and thermal stability. The improved PTFE/ZnO/SiO2 composite can, therefore, be used as a self-cleaning layer for astronaut suits based on the findings of relatively high mobility, minimal reactivity to the surrounding environment, and thermal stability.

Effect of CuO and Graphene on PTFE Microfibers: Experimental and Modeling Approaches.

The surface of pure polytetrafluoroethylene (PTFE) microfibers was modified with ZnO and graphene (G), and the composite was studied using ATR-FTIR, XRD, and FESEM. FTIR results showed that two significant bands appeared at 1556 cm-1 and 515 cm-1 as indications for CuO and G interaction. The SEM results indicated that CuO and G were distributed uniformly on the surface of the PTFE microfibers, confirming the production of the PTFE/CuO/G composite. Density functional theory (DFT) calculations were performed on PTFE polymer nanocomposites containing various metal oxides (MOs) such as MgO, Al2O3, SiO2, TiO2, Fe3O4, NiO, CuO, ZnO, and ZrO2 at the B3LYP level using the LAN2DZ basis set. Total dipole moment (TDM) and HOMO/LUMO bandgap energy ΔE both show that the physical and electrical characteristics of PTFE with OCu change to 76.136 Debye and 0.400 eV, respectively. PTFE/OCu was investigated to observe its interaction with graphene quantum dots (GQDs). The results show that PTFE/OCu/GQD ZTRI surface conductivity improved significantly. As a result, the TDM of PTFE/OCu/GQD ZTRI and the HOMO/LUMO bandgap energy ΔE were 39.124 Debye and ΔE 0.206 eV, respectively. The new electrical characteristics of PTFE/OCu/GQD ZTRI indicate that this surface is appropriate for electronic applications.

Electronic and physical studies for Teflon FEP as a thermal control in low earth orbit reinforced with ZnO and SiO2 nanoparticles.

Fluorinated ethylene propylene (Teflon FEP) was used as external layer thermal insulator for Hubble Space Telescope (HST) and on the outside surfaces of space crafts in the low earth orbit (LEO). Teflon FEP was eroding as a result of exposure to atomic oxygen (AO) and different electromagnetic waves such as ultraviolet radiation and X-ray. Model molecules were used to simulate Teflon FEP and its interaction with other nanoparticles such as ZnO and SiO2. Density functional theory (DFT) was used to calculate model structures using B3LYP/LAN2DZ model. Molecular electrostatic potential as contour, band gap energy, and total dipole moment were computed for all models. Thermal stability properties were also studied for Teflon FEP both individually and interacted with ZnO and SiO2. Results showed that a layer of OZn and SiO2 on Teflon FEP, especially Teflon FEP + OZn + OSiO structure, improves the physical, chemical, thermal, and electrical stability of Teflon FEP, potentially acting as a corrosion-inhibiting layer.