ISSN / EISSN : 2470-1343 / 2470-1343
Published by: American Chemical Society (ACS) (10.1021)
Total articles ≅ 11,367
Latest articles in this journal
ACS Omega; doi:10.1021/acsomega.1c02639
Vacancy defects are inherent point defects in materials. In this study, we investigate the role of Fe vacancy (VFe) and S vacancy (VS) in the interaction (adsorption, dissociation, and diffusion) between H2S and the FeS(001) surface using the dispersion-corrected density functional theory (DFT-D2) method. VFe promotes the dissociation of H2S but slightly hinders the dissociation of HS. Compared with the perfect surface (2.08 and 1.15 eV), the dissociation energy barrier of H2S is reduced to 1.56 eV, and HS is increased to 1.25 eV. Meanwhile, S vacancy (VS) significantly facilitates the adsorption and dissociation of H2S, which not only reduces the dissociation energy barriers of H2S and HS to 0.07 and 0.11 eV, respectively, but also changes the dissociation process of H2S from an endothermic process to a spontaneous exothermic one. Furthermore, VFe can promote the hydrogen (H) diffusion process from the surface into the matrix and reduce the energy barrier of the rate-limiting step from 1.12 to 0.26 eV. But it is very hard for H atoms gathered around VS to diffuse into the matrix, especially the energy barrier of the rate-limiting step increases to 1.89 eV. Finally, we propose that VS on the FeS(001) surface is intensely difficult to form and exist in the actual environment through the calculation results.
ACS Omega; doi:10.1021/acsomega.1c01898
The first-principles calculation of pristine, B-, Al-, Ga-, Sb-, and Bi-doped blue phosphorene (BlueP) with adsorbed SO2, NO, and NO2 gas molecules including the transport and optical properties is reported. The electronic structures of pristine and doped BlueP are investigated, and the modifications in electronic band structures and density (DOS) of states are studied. The most considerable adsorption energies of BlueP after being exposed to paramagnetic gas molecules NO and NO2 show excellent sensitivity to the considered gas molecules, which is confirmed by the current–voltage characteristics. The pristine and doped BlueP can be encouraging alternatives for new-generation optical gas sensors due to notable alterations in the pristine and doped BlueP optical spectra.
ACS Omega, Volume 6; doi:10.1021/aov006i027_1494752
ACS Omega, Volume 6; doi:10.1021/aov006i027_1494753
ACS Omega; doi:10.1021/acsomega.1c02402
The energy demand of the world is skyrocketing due to the exponential economic growth and population expansion. To meet the energy requirement, the use of fossil fuels is not a good decision, causing environmental pollution such as CO2 emissions. Therefore, the use of renewable energy sources like biofuels can meet the energy crisis especially for countries facing oil shortages such as Pakistan. This review describes the comparative study of biodiesel synthesis for various edible oils, non-edible oils, and wastes such as waste plastic oil, biomass pyrolysis oil, and tyre pyrolysis oil in terms of their oil content and extraction, cetane number, and energy content. The present study also described the importance of biodiesel synthesis via catalytic transesterification and its implementation in Pakistan. Pakistan is importing an extensive quantity of cooking oil that is used in the food processing industries, and as a result, a huge quantity of waste cooking oil (WCO) is generated. The potential waste oils for biodiesel synthesis are chicken fat, dairy scum, WCO, and tallow oil that can be used as potential substrates of biodiesel. The implementation of a biodiesel program as a replacement of conventional diesel will help to minimize the oil imports and uplift the country’s economy. Biodiesel production via homogeneous and heterogeneous catalyzed transesterification is more feasible among all transesterification processes due to a lesser energy requirement and low cost. Therefore, biodiesel synthesis and implementation could minimize the imports of diesel by significantly contributing to the overall Gross Domestic Product (GDP). Although, waste oil can meet the energy needs, more available cultivation land should be used for substrate cultivation. In addition, research is still needed to explore innovative solvents and catalysts so that overall biodiesel production cost can be minimized. This would result in successful biodiesel implementation in Pakistan.
ACS Omega; doi:10.1021/acsomega.1c00493
In this work, zeolitic imidazolate frameworks (ZIF-8) and carboxylated carbon nanotubes (CNTs) were compounded to prepare a kebab-like one-dimensional linear composite, [email protected] The mixed-matrix membrane (MMM) for separating carbon dioxide is prepared by embedding it into the polymer matrix Pebax-1657. The results indicated the successful synthesis of the [email protected] composite. The combination of ZIF-8 and carboxylated CNTs avoided the aggregation of ZIF-8 in the polymer, increased the free volume of the MMM, and enhanced the CO2 adsorption performance and CO2/N2 separation performance. In addition, the interaction between CNTs and ZIF-8 provided a fast transport channel for CO2 molecules and improved the mechanical properties of the MMM. The 5 wt % [email protected] MMM showed the best separation performance with a CO2 permeability of 225.5 Barrer and a CO2/N2 selectivity of 48.9, which exceeded the Robeson upper limit in 2008. The combination of high permeability and selectivity made Pebax/[email protected] MMMs promising for industrial CO2 separation applications.
ACS Omega; doi:10.1021/acsomega.1c02072
Aluminum (Al)-based metal–organic frameworks (MOFs) have been shown to have good stability toward γ irradiation, making them promising candidates for durable adsorbents for capturing volatile radioactive nuclides. In this work, we studied a series of existing Al-MOFs to capture trace radioactive organic iodide (ROI) from a gas composition (100 ppm CH3I, 400 ppm CO2, 21% O2, and 78% N2) resembling the off-gas composition from reprocessing the used nuclear fuel using Grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) calculations. Based on the results and understanding established from studying the existing Al-MOFs, we proceed by functionalizing the top-performing CAU-11 with different functional groups to propose better MOFs for ROI capture. Our study suggests that extraordinary ROI adsorption and separation capability could be realized by −SO3H functionalization in CAU-11. It was mainly owing to the joint effect of the enhanced pore surface polarity arising from −SO3H functionalization and the μ-OH group of CAU-11.
ACS Omega; doi:10.1021/acsomega.1c02118
Adenine is one of the basic molecules of life; it is also an important building block in the synthesis of new pharmaceuticals, electrochemical (bio)sensors, or self-assembling molecular materials. Therefore, it is important to know the effects of the solvent and substituent on the electronic structure of adenine tautomers and their stability. The four most stable adenine amino tautomers (9H, 7H, 3H, and 1H), modified by substitution (C2– or C8−) of electron-withdrawing NO2 and electron-donating NH2 groups, are studied theoretically in the gas phase and in solvents of different polarities (1 ≤ ε < 109). Solvents have been modeled using the polarizable continuum model. Comparison of the stability of substituted adenine tautomers in various solvents shows that substitution can change tautomeric preferences with respect to the unsubstituted adenine. Moreover, C8 substitution results in slight energy differences between tautomers in polar solvents (<1 kcal/mol), which suggests that in aqueous solution, C8–X-substituted adenine systems may consist of a considerable amount of two tautomers—9H and 7H for X = NH2 and 3H and 9H for X = NO2. Furthermore, solvation enhances the effect of the nitro group; however, the enhancement strongly depends on the proximity effects. This enhancement for the NO2 group with two repulsive N···ON contacts can be threefold higher than that for the NO2 with one attractive NH···ON contact. The proximity effects are even more significant for the NH2 group, as the solvation may increase or decrease its electron-donating ability, depending on the type of proximity.
ACS Omega; doi:10.1021/acsomega.1c02798
The products of the Friedlander reaction, i.e., 1,8-naphthyridines, have far-reaching impacts in materials science, chemical biology, and medicine. The reported synthetic methodologies elegantly orchestrate the diverse synthetic routes of naphthyridines but require harsh reaction conditions, organic solvents, and expensive metal catalysts. Here, we introduce gram-scale synthesis of 1,8-naphthyridines in water using an inexpensive and biocompatible ionic liquid (IL) as a catalyst. This is the first-ever report on the synthesis of naphthyridines in water. This is a one-step reaction, and the product separation is relatively easy. The choline hydroxide (ChOH) is used as a metal-free, nontoxic, and water-soluble catalyst. In comparison to other catalysts reported in the literature, ChOH has the advantage of forming an additional hydrogen bond with the reactants, which is the vital step for the reaction to happen in water. Density functional theory (DFT) and noncovalent interaction (NCI) plot index analysis provide the plausible reaction mechanism for the catalytic cycle and confirm that hydrogen bonds with the IL catalyst are pivotal to facilitate the reaction. Molecular docking and molecular dynamics (MD) simulations are also performed to demonstrate the potentialities of the newly synthesized products as drugs. Through MD simulations, it was established that the tetrahydropyrido derivative of naphthyridine (10j) binds to the active sites of the ts3 human serotonin transporter (hSERT) (PDB ID: 6AWO) without perturbing the secondary structure, suggesting that 10j can be a potential preclinical drug candidate for hSERT inhibition and depression treatment.
ACS Omega; doi:10.1021/acsomega.1c02179
Practical application of surface-enhanced Raman spectroscopy (SERS) is greatly limited by the inaccurate quantitative analyses due to the measuring parameter’s fluctuations induced by different operators, different Raman spectrometers, and different test sites and moments, especially during the field tests. Herein, we develop a strategy of quantitative SERS for field detection via designing structurally homogeneous and ordered Ag-coated Si nanocone arrays. Such an array is fabricated as SERS chips by depositing Ag on the template etching-induced Si nanocone array. Taking 4-aminothiophenol as the typical analyte, the influences of fluctuations in measuring parameters (such as defocusing depth and laser powers) on Raman signals are systematically studied, which significantly change SERS measurements. It has been shown that the silicon underneath the Ag coating in the chip can respond to the measuring parameters’ fluctuations synchronously with and similar to the analyte adsorbed on the chip surface, and the normalization with Si Raman signals can well eliminate the big fluctuations (up to 1 or 2 orders of magnitude) in measurements, achieving highly reproducible measurements (mostly, <5% in signal fluctuations) and accurate quantitative SERS analyses. Finally, the simulated field tests demonstrate that the developed strategy enables quantitatively analyzing the highly scattered SERS measurements well with 1 order of magnitude in signal fluctuation, exhibiting good practicability. This study provides a new practical chip and reliable quantitative SERS for the field detection of real samples.