A challenging task is to promote Ru atom economy and simultaneously alleviate Ru dissolution during the hydrogen evolution reaction (HER) process. Herein, Ru nanograins (≈1.7 nm in size) uniformly ...grown on 1T‐MoS2 lace‐decorated Ti3C2Tx MXene sheets (Ru@1T‐MoS2‐MXene) are successfully synthesized with three types of interfaces (Ru/MoS2, Ru/MXene, and MoS2/MXene). It gives high mass activity of 0.79 mA µgRu−1 at an overpotential of 100 mV, which is ≈36 times that of Ru NPs. It also has a much smaller Ru dissolution rate (9 ng h−1), accounting for 22% of the rate for Ru NPs. Electrochemical tests, scanning electrochemical microscopy measurements combined with DFT calculations disclose the role of triple interface optimization in improved activity and stability. First, 2D MoS2 and MXene can well disperse and stabilize Ru grains, giving larger electrochemical active area. Then, Ru/MoS2 interfaces weakening H* adsorption energy and Ru/MXene interfaces enhancing electrical conductivity, can efficiently improve the activity. Next, MoS2/MXene interfaces can protect MXene sheet edges from oxidation and keep 1T‐MoS2 phase stability during the long‐term catalytic process. Meanwhile, Ru@1T‐MoS2‐MXene also displays superior activity and stability in neutral and alkaline media. This work provides a multiple‐interface optimization route to develop high‐efficiency and durable pH‐universal Ru‐based HER electrocatalysts.
The hybrid catalyst of Ru@1T‐MoS2‐MXene with three types of interfaces (Ru/MoS2, Ru/MXene, and MoS2/MXene), gives 36 times higher mass activity and ≈5 times enhanced durability compared with Ru because of the weakened H* adsorption energy, increased conductivity, stabilized MXene, and 1T‐MoS2, and decreased Ru dissolution endowed by multi‐functional interfaces.
To develop quick‐charge sodium‐ion battery, it is significant to optimize insertion‐type anode to afford fast Na+ diffusion rate and excellent electron conductivity. First‐principles calculations ...reveal the TiO subcompound superiority for Na+ diffusion following Ti(II)O > Ti(III)O > Ti(IV)O. Hence, in situ growth of amorphous TiO subcompounds with rich oxygen defects based on Ti3C2Tx‐MXene is developed. Meanwhile, the composite presents expanded MXene interlayer spacing and much enhanced conductivity. The synergistic effect of enhanced electron/ion conduction gives a high capacity of 107 mAh g−1 at 50 A g−1, which gives 50% and 150% increasements compared with one counterpart without valence adjustment and another one without MXene expansion. It only needs 20 s (at 30 A g−1) to complete the discharge/charge process and obtains a capacity of 144.5 mAh g−1, which also shows a long‐term cycling stability at quick‐charge mode (121 mAh g−1 after 10000 cycles at 10 A g−1). The enhanced performance comes from fast electron transfer among TiO subcompounds contributed by rich‐defect amorphous TiO2–x, and a reversible change of elastic MXene with interlayer spacing between 1.4 and 1.9 nm during Na+ insertion/extraction process. This study provides a feasible route to boost the kinetics and develop quick‐charge sodium‐ion battery.
The composite of elastic S‐doped Ti3C2Tx MXene with 18.2% expanded interlayer spacing and amorphous TiO2–x gives a specific capacity of 121 mAh g−1 at 10 A g−1 after 10 000 cycles, showing great potential in developing functional fast‐charge sodium‐ion batteries. The fast Na+ storage kinetic process and stability comes from optimized insertion‐type MXene and fast electron transfer among TiO subcompounds.
Density functional theory (DFT) calculations demonstrate neighboring Pt atoms can enhance the metal activity of NiCoP for hydrogen evolution reaction (HER). However, it remains a great challenge to ...link Pt and NiCoP. Herein, we introduced curvature of bowl‐like structure to construct Pt/NiCoP interface by adding a minimal 1 ‰‐molar‐ratio Pt. The as‐prepared sample only requires an overpotential of 26.5 and 181.6 mV to accordingly achieve the current density of 10 and 500 mA cm−2 in 1 M KOH. The water dissociation energy barrier (Ea) has a ~43 % decrease compared with NiCoP counterpart. It also shows an ultrahigh stability with a small degradation rate of 10.6 μV h−1 at harsh conditions (500 mA cm−2 and 50 °C) after 3000 hrs. X‐ray photoelectron spectroscopy (XPS), soft X‐ray absorption spectroscopy (sXAS), and X‐ray absorption fine structure (XAFS) verify the interface electron transfer lowers the valence state of Co/Ni and activates them. DFT calculations also confirm the catalytic transition step of NiCoP can change from Heyrovsky (2.71 eV) to Tafel step (0.51 eV) in the neighborhood of Pt, in accord with the result of the improved Hads at the interface disclosed by in situ electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) tests.
Hydrogen evolution reaction (HER) activity of Ni/Co can be improved by neighboring Pt atoms in alkaline electrolyte, which can increase water adsorption and decrease dramatically water dissociation energy barrier by interface electron transfer, and even change catalytic route from Heyrovsky to faster Tafel step.
1,2-Dicarbofunctionalization of alkenes represents an appealing strategy for chemical bond formation in organic synthesis, which could enable the rapid construction of molecular complexity from ...simple and readily available starting materials by incorporating two functional groups onto a carbon-carbon double bond in one step. In this field, the dicarbofunctionalization of alkenes with different alkyl radicals in a controlled manner represents an elegant and versatile strategy to access structurally diverse functionalized alkanes, which have witnessed significant progress over the last five years. Due to the importance of alkyl radicals in organic synthesis and medicinal chemistry, this review provides a comprehensive perspective on the development of alkyl radical precursors including electrophilic precursors such as alkyl halides, alkyl peroxides, alkyl NHP esters, cycloketone oxime esters, and Katritzky pyridinium salts, and nucleophilic precursors such as alkyl acids, alkyl oxalates, alkylborates, alkylsilicates, and unactivated hydrocarbons, which generate alkyl radicals by photocatalysis or transition metal catalysis to engage in dicarbofunctionalization under oxidative reaction conditions, redox-neutral conditions, or reductive conditions. The mechanisms of these dicarbofunctionalization reactions have also been discussed in detail.
This article provides a comprehensive perspective on three-component 1,2-dicarbofunctionalization of alkenes involving alkyl radicals, which generated from structurally diverse electrophilic and nucleophilic precursors under mild conditions.
Hydrogen peroxide (H
O
) plays a key role in the progression of human illnesses, such as autoimmune and auto-inflammatory diseases, infectious diseases, diabetes, and cancer, etc. In this work, we ...have discribed a novel probe, TPE-TLE, which remarkably displayed AIE property and ratiometric fluorescence emission profiles in the presence of H
O
This ratiometric fluorescent probe with AIE property exhibits outstanding features such as the well-resolved emission peaks, high sensitivity, high selectivity, low cytotoxicity, and good cell-membrane permeability. These excellent attributes enable us to demonstrate the ratiometric imaging of endogenously produced H
O
in macrophages and cancer cells based on the novel ratiometric probe with AIE property for the first time. By comparing two kinds of cells, it is firstly found that cancer cells should contain much more endogenous H
O
than macrophages. We expect that TPE-TLE will be useful fluorescent platform for the development of a variety of ratiometric fluorescent probes with AIE property to achieve unique biological applications.
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Alkaline hydrogen evolution reaction (HER) electrocatalysts with high catalytic activity and long-term durability are of significance for sustainable energy applications. Herein, we ...prepared trimetallic PtNiCo hollow alloyed 3D multipods (HAMPs) with rough surfaces by an effective one-pot solvothermal strategy coupled with acid etching, as evidenced by a series of characterizations. By virtue of the trimetals and unique structures, the PtNiCo HAMPs exhibited excellent HER performance in 1.0 M KOH electrolyte with a low overpotential (η, 20 mV) and small Tafel slope (46.3 mV dec−1), superior to homemade PtNi HAMPs, PtCo nanocrystals (NCs) and commercial Pt/C catalysts. This study provides some constructive guidelines for synthesis of advanced hollow multimetallic catalysts in energy systems.
Melatonin, a major hormone of the pineal gland, exerts many beneficial effects on mitochondria. Several studies have shown that melatonin can protect against toxin‐induced oocyte quality impairment ...during maturation. However, there is little information regarding the beneficial effects of melatonin on toxin‐exposed early embryos, and the mechanisms underlying such effects have not been determined. Rotenone, a chemical widely used in agriculture, induces mitochondrial toxicity, therefore, damaging the reproductive system, impairing oocyte maturation, ovulation, and fertilization. We investigated whether melatonin attenuated rotenone exposure‐induced impairment of embryo development by its mitochondrial protection effect. Activated oocytes were randomly assigned to four groups: the control, melatonin treatment, rotenone‐exposed, and “rotenone + melatonin” groups. Treatment with melatonin abrogated rotenone‐induced impairment of embryo development, mitochondrial dysfunction, and ATP deficiency, and significantly decreased oxidative stress and apoptosis. Melatonin also increased SIRT1 and PGC‐1α expression, which promoted mitochondrial biogenesis. SIRT1 knockdown or pharmacological inhibition abolished melatonin's ability to revert rotenone‐induced impairment. Thus, melatonin rescued rotenone‐induced impairment of embryo development by reducing ROS production and promoting mitochondrial biogenesis. This study shows that melatonin rescues toxin‐induced impairment of early porcine embryo development by promoting mitochondrial biogenesis.
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Exploring hydrogen evolution reaction (HER) catalyst with highly catalytic features in alkaline conditions is considered as significance for water splitting. In this study, a general ...and simple method was developed to prepare flower-like platinum-cobalt-ruthenium alloy nanoassemblies (PtCoRu NAs) by using murexide and cetyltrimethylammonium chloride (CTAC) as the co-structure-directing agents. Benefiting from the structural advantages and multimetallic compositions, the as-prepared PtCoRu NAs displayed remarkably enhanced electrocatalytic performance for the HER in 1.0 M KOH, with a low overpotential (η, 22 mV) to drive 10 mA cm−2, small Tafel slope (46 mV dec−1), and high exchange current density (j0, 3.30 mA cm−2) during the long-term electrolysis. The as-developed strategy sheds some valuable guidelines for preparing advanced multimetallic catalysts for production of hydrogen in fuel cells.
Abstract
The occurrence of toxic metals in the aquatic environment is as caused by a variety of contaminations which makes difficulty in the concentration prediction. In this study, conventional ...methods of back-propagation neural network (BPNN) and nonlinear autoregressive network with exogenous inputs (NARX) were applied as benchmark models. Explanatory variables of Fe, pH, electrical conductivity, water temperature, river flow, nitrate nitrogen, and dissolved oxygen were used as different input combinations to forecast the long-term concentrations of As, Pb, and Zn. The wavelet transformation was applied to decompose the time series data, and then was integrated with conventional methods (as WNN and WNARX). The modelling performances of the hybrid models of WNN and WNARX were compared with the conventional models. All the given models were trained, validated, and tested by an 18-year data set and demonstrated based on the simulation results of a 2-year data set. Results revealed that the given models showed general good performances for the long-term prediction of the toxic metals of As, Pb, and Zn. The wavelet transform could enhance the long-term concentration predictions. However, it is not necessarily useful for each metal prediction. Therefore, different models with different inputs should be used for different metals predictions to achieve the best predictions.
As one of the most widely investigated compound skeleton, quinolines possess important medicinal and biological activities. As such, a great number of literatures, including reviews, have reported ...various methodologies to construct quinolines. Recently, organocatalyzed reactions have attracted the attention of organic chemists due to its being "green" because the reactions avoid the use of toxic metals. In this review, various distinctive contributions are surveyed with specific emphasis on organocatalyzed reactions for quinoline core constructions.
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