Edges of FeO/Pt(111) Interface: A First-Principle Theoretical Study

An understanding of the reaction mechanisms of oxide/metal bicatalysts is important for their design to achieve better catalytic performance. Using the density functional theory calculations based on the GGA+U approach, the ferrous oxide (FeO) clusters on Pt(111) were systematically investigated as a model of oxide/metal bicatalyst since they showed high catalytic capacity on the preferential oxidation of carbon monoxide. Our calculations showed that the role of the coordinatively unsaturated ferrous (CUF) atoms at the edges of the FeO/Pt(111) interface was to help the dissociative adsorption of oxygen molecules. The oxygen atoms at the edges in the intermediate were more chemically active according to the analysis of their electronic properties. They can selectively attract the carbon monoxide molecules to oxide them. After the desorption of carbon dioxide molecules, the CUF atoms at the edges can be reproduced. The high efficiency and selectivity of FeO/Pt(111) bicatalysts were, therefore, explained using our theoretical results

Theoretical Understanding and Prediction of Lithiated Sodium Hexatitanates

Sodium hexatitanates (Na₂Ti₆O₁₃) with tunnelled structures have been experimentally proposed to be good candidates for anode materials of lithium ion batteries because of their low potential, small shape transformation, and good reversibility. The understanding of the properties of this lithiated titanate is significant for their development. To this end, the first-principle calculations were performed to investigate the interaction between Li ions and Na₂Ti₆O₁₃ at the atomic level. After structural optimization with various Li:Ti ratios, the Li ions are found to energetically prefer to stay at the small rhombic tunnels of Na₂Ti₆O₁₃, where the diffusion energy barrier of Li ions is also lower. Such preference is determined by the chemical environment around Li ions. Our theoretical intercalation potential and volume change on the basis of the optimized atomic structures agree with the experimental observations. The analysis of the electronic properties reveals the Burstein–Moss effect in lithiated Na₂Ti₆O₁₃ due to the heavy n-type doping. Such materials possess high conductivity, which can benefit their applications in photoelectrochemical or electrochemical areas

Ball Milling-Induced Plate-like Sub-microstructured Iron for Enhancing Degradation of DDT in a Real Soil Environment

The remediation of soil contaminated by 1,1,1-trichloro-2,2-bis­(4-chlorophenyl) ethane (DDT) has been a challenge. In this paper, the degradation performances of the ball milling-induced plate-like sub-microstructured zero valent iron (SMZVI) to DDT in a real soil environment is studied. It has been found that such SMZVI exhibits much higher degradation performances to DDT in soil than commercial ZVI powders under acidic conditions. More than 95% DDT could be degraded within 80 min in the 5 ppm DDT-contaminated soil with addition of 50 mg g^–1 SMZVI, which is much better than the previously reported results. The time-dependent DDT removal amount can be well described by the pseudo first-order kinetic model. Further experiments have revealed that the ZVI dosages, surfactant’s and acidic additions, and the weight ratio of soil-to-water in the slurries are important to DDT degradation, and the degradation products were mainly DDD (a product with less chlorine). An acid-assisted ZVI-induced reductive dechlorination process is proposed, which can well explain the DDT degradation behaviors in soil and the influence from the other factors. This work not only deepens the understanding of DDT degradation in soils based on ZVI but also demonstrates that the SMZVI could be a promising material for DDT degradation in real environments

Silver-Catalyzed Ring-Opening Strategy for the Synthesis of β- and γ‑Fluorinated Ketones

A regioselective synthesis of β- and γ-fluorinated ketones via silver-catalyzed ring opening is described. A variety of β- and γ-fluorinated ketones are efficiently prepared, respectively, from tertiary cyclopropanol and cyclobutanol precursors, providing a straightforward approach for the introduction of a fluorine atom into complex molecules. Preliminary mechanistic studies suggest that a radical-mediated sequential C–C bond cleavage and C–F bond formation pathway is involved

Pseudocapacitance of Cl-Terminated MXene Nanosheets for Efficient Chloride-Ion Hybrid Capacitors

Chloride-ion batteries (CIBs) have the advantages of being widely sourced, environmentally friendly, and having high theoretical volumetric energy density (2500 Wh·L–1). However, the electrochemical reaction kinetics and cycle performance of CIBs suffer from poor structural reversibility and insufficient electrical conductivity of chlorine storage materials. Herein, we report the synthesis of a Cl-terminated MXene (Ti3C2Cl2) with high Cl– capacity and low Cl– diffusion barrier as a cathode material for chloride-ion hybrid capacitors (CHCs). The constructed Ti3C2Cl2 electrode delivers a gravimetric capacity of 536 mAh·g–1 and a Coulombic efficiency of >99.5% after 1000 cycles of charge and discharge at a current density of 0.2 A·g–1. It also exhibits superior rate capability of 153.1 mAh·g–1 at 1 A·g–1 and 121.2 mAh·g–1 at 2 A·g–1, respectively

Enhanced Desalination Performance by a Novel Archimedes Spiral Flow Channel for Flow-Electrode Capacitive Deionization

As an emerging desalination technology, flow-electrode capacitive deionization (FCDI) has aroused extensive attraction due to its advantage of pseudoinfinite adsorption capacity. However, some problems still remain in the traditional FCDI devices, i.e., its streaming and seeping quality which has severely limited the progress. Herein, some improvements were achieved by changing the direction of saline water in spacer. Furthermore, the Archimedes spiral flow channel model was introduced to improve the flow behavior of carbon slurry in the FCDI unit cell for the first time, which has vastly boosted the desalination performance of FCDI devices. The computational fluid dynamics (CFD) simulation revealed the more uniform velocity distribution and longer residence time of carbon slurry in spiral flow channels to enhance the desalination, while the flow rate of carbon slurry in a straight line is faster but slower in the corner of serpentine flow channels, causing a negative effect on the desalination performance. After long-term continuous desalination in 3.5 g L–1 NaCl solution at 2.4 V, 99.88% of salt removal efficiency was achieved with a superior salt removal rate of 4.06 μmol cm–2 min–1 and 98.9% charge efficiency for the spiral flow channel FCDI device, demonstrating a stable desalination performance

Fluorescence Determination of Nitrite in Water Using Prawn-Shell Derived Nitrogen-Doped Carbon Nanodots as Fluorophores

In this work, we report the synthesis of nitrogen (N)-doped carbon nanodots (N-CNDs) with an N doping level of 3.6 at. % by hydrothermal treatment of prawn shell and their application as fluorophores for selective and sensitive fluorescence detection of NO₂^– in water. The results demonstrate that NO₂^– detection by directly fluorescent quenching at N-CNDs fluorophores can achieve an analytical detection linear range up to 1.0 mM with a detection limit of 1.0 μM. The obtained detection limit of NO₂^– using N-CNDs fluorophores is dramatically lower than the maximum limit value of 3.0 mg L^–1 (namely, 65 μM) for NO₂^– in drinking water ruled by the World Health Organization (WHO), which is very important for a practical application of the developed analytical method. The interference experiments indicate that only I^– ions among all common anions and cations investigated show very adverse influence on selective detection of NO₂^– by this developed N-CNDs based fluorescent determination method. Further, the fluorescence quenching of N-CNDs on NO₂^– concentrations under the given experimental conditions fits a linear Stern–Volmer relationship very well, indicating a dynamic quenching process in this N-CNDs/NO₂^– fluorescence sensing system. A fluorescent quenching mechanism resulted from the redox reaction between the excited oxidation state of N-CNDs under light excitation and NO₂^– was proposed based on the experimental results. The findings in this work exhibit the great potential using cheap and abundant biomass-derived N-doped carbon nanodots as fluorophores for selective and sensitive determination of environmentally harmful anions

Microwave-Assisted Fabrication of Nanoparticulate TiO₂ Microspheres for Synergistic Photocatalytic Removal of Cr(VI) and Methyl Orange

High yield production of micro/nanostructured nanoparticulate TiO2 microspheres (NTMs) via a facile microwave-assisted hydrothermal approach was investigated. The rapid and uniform microwave heating could reduce the reaction time to 30 min, an order of magnitude shorter than that of conventional hydrothermal methods. The characterization data confirmed that the resultant NTMs were highly uniform in size, having an average diameter of ∼0.5 μm. The obtained NTMs were found to be constructed by well-crystallized anatase phase nanoparticles ranging from 5 to 10 nm that can be readily controlled by the microwave radiation temperature. Nitrogen sorption isotherm analysis revealed that the obtained NTMs possessed abundant mesoporous structures with a high specific surface area of 124 m2 g–1. An in situ self-aggregation formation process under controllable pH in presence of urea was proposed. The results obtained from the application of NTMs for simultaneous photocatalytic decontamination of Cr­(VI) and methyl orange (MO) demonstrated a strong synergistic effect that dramatically enhanced both Cr­(VI) reduction and MO oxidation removal efficiencies. This work not only enriched the synthesis methods of the micro/nanostructured TiO2, but also provided a new means to improve the photocatalytic efficiency via structural-induced synergistic effect, applicable to the other catalysis systems

Image_1_Proton pump inhibitors induced fungal dysbiosis in patients with gastroesophageal reflux disease.jpeg

Gut mycobiota inhabits human gastrointestinal lumen and plays a role in human health and disease. We investigated the influence of proton pump inhibitors (PPIs) on gastric mucosal and fecal mycobiota in patients with gastroesophageal reflux diseases (GERD) by using Internal Transcribed Spacer 1 sequencing. A total of 65 participants were included, consisting of the healthy control (HC) group, GERD patients who did not use PPIs (nt-GERD), and GERD patients who used PPIs, which were further divided into short-term (s-PPI) and long-term PPI user (l-PPI) groups based on the duration of PPI use. The alpha diversity and beta diversity of gastric mucosal mycobiota in GERD patients with PPI use were significantly different from HCs, but there were no differences between s-PPI and l-PPI groups. LEfSe analysis identified Candida at the genus level as a biomarker for the s-PPI group when compared to the nt-GERD group. Meanwhile, Candida, Nothojafnea, Rhizodermea, Ambispora, and Saccharicola were more abundant in the l-PPI group than in the nt-GERD group. Furthermore, colonization of Candida in gastric mucosa was significantly increased after PPI treatment. However, there was no significant difference in Candida colonization between patients with endoscopic esophageal mucosal breaks and those without. There were significant differences in the fecal mycobiota composition between HCs and GERD patients regardless whether or not they used PPI. As compared to nt-GERD patient samples, there was a high abundance of Alternaria, Aspergillus, Mycenella, Exserohilum, and Clitopilus in the s-PPI group. In addition, there was a significantly higher abundance of Alternaria, Aspergillus, Podospora, Phallus, and Monographella in the l-PPI group than nt-GERD patients. In conclusion, our study indicates that dysbiosis of mycobiota was presented in GERD patients in both gastric mucosal and fecal mycobiota. PPI treatment may increase the colonization of Candida in the gastric mucosa in GERD patients.</p

Lignocellulose Aerogel from Wood-Ionic Liquid Solution (1-Allyl-3-methylimidazolium Chloride) under Freezing and Thawing Conditions

This article reports a facile preparation of a lignocellulose aerogel from a solution of wood in an ionic liquid by cyclic freeze−thaw (FT) process. Trema orientalis wood flour was dissolved in 1-allyl-3-methylimidazolium chloride (AMImCl), an effective ionic liquid, and then repeatedly frozen at −20 °C and thawed at 20 °C for several times, and then finally regenerated in water. The hydrogel obtained was solvent-exchanged to acetone, washed with liquid carbon dioxide, and finally dried by releasing the carbon dioxide at critical temperature to obtain the lignocellulose aerogel. The aerogel had an open 3D fibrillar network and could be transformed from nanofibrillar to sheet-like skeletons with hierarchical micro- and nanoscale morphology and porosity by adjusting the FT treatment cycles. The frequency of FT cycles influenced the intensity, specific surface, crystallinity, and thermostability of the aerogel. This research highlights new opportunities for the development of porous and flexible aerogel scaffolds