Search

The development of efficient systems for the catalytic oxidation of 2-nitro-4-methylsulfonyltoluene (NMST) to 2-nitro-4-methylsulfonyl benzoic acid (NMSBA) with atmospheric air or molecular oxygen in alkaline medium presents a significant challenge for the chemical industry. Here, we report the synthesis of FeOOH/Fe3O4/metal–organic framework (MOF) polygonal mesopores microflower templated from a MIL-88B(Fe) at room temperature, which exposes polygonal mesopores with atomistic edge steps and lattice defects. The obtained FeOOH/Fe3O4/MOF catalyst was adsorbed onto glass beads and then introduced into the microchannel reactor. In the alkaline environment, oxygen was used as oxidant to catalyze the oxidation of NMST to NMSBA, showing impressive performance. This sustainable system utilizes oxygen as a clean oxidant in an inexpensive and environmentally friendly NaOH/methanol mixture. The position and type of substituent critically affect the products. Additionally, this sustainable protocol enabled gram-scale preparation of carboxylic acid and benzyl alcohol derivatives with high chemoselectivities. Finally, the reactions can be conducted in a pressure reactor, which can conserve oxygen and prevent solvent loss. Moreover, compared with the traditional batch reactor, the self-built microchannel reactor can accelerate the reaction rate, shorten the reaction time, and enhance the selectivity of catalytic oxidation reactions. This approach contributes to environmental protection and holds potential for industrial applications.

In the first step, the Ag nanoparticles doped Ni(OH) 2 nanoflower arrays were directly in situ grown on the NF (Ag-Ni(OH) 2 /NF) by hydrothermal method. In the second step, the Ag doped NiMo LDH nanorod arrays were directly grow on the NF during the hydrothermal stage with the pyrolysis of was immersed into a solution mixture of Na 2 MoO 4 and urea, which resulted in the precipitation of NiMo LDH/Ag/NF. In the third step, the as-prepared NiMo LDH/Ag/NF was completely converted into NiCo 2 O 4 /Ag/NF at elevated temperature in a tube furnace. [Display omitted] • Crossed nanorod with high specific surface area and 1D properties was synthesized. • NiMoO 4 /Ag/NF exhibits high OER activity and low Tafel slope. • The catalytic performance is improved by annealing to produce a rich oxygen gap. The development of low-cost and highly efficient electrocatalysts for oxygen evolution reaction (OER) with good conductivity, high specific surface area and abundant oxygen vacancies is of great significance for the future renewable energy conversion and storage system. Herein, Ag doped NiMoO 4 materials on the Ni foam (NiMoO 4 /Ag/NF) with rich oxygen vacancies were successfully prepared by hydrothermal strategy and layer by layer assembly method. The Ag ions are doped in-situ to promote electron transfer and compensate for the poor conductivity of metal oxides. The suitable air annealing treatment is used to create rich oxygen vacancies. The high specific surface area and one-dimensional characteristics of the cross mesoporous nanorod skeleton are responsible for the increased exposure of active centers and the rapid charge transfer behavior. The NiMoO 4 /Ag/NF exhibits high activity for OER in alkaline solution (an overpotential of 275 mV at the current density of 20 mA cm−2) and low Tafel slope (53.67 mV dec−1), and a satisfying durability in 1.0 M KOH. This study provides an effective method for the preparation of Ag doped one-dimensional nanomaterials with excellent OER catalytic performance and electrochemical stability. [ABSTRACT FROM AUTHOR]

For antibiotic contaminants, biomass have been regarded as one of the most resource of functional carbonaceous materials due to its biocompatibility, biodegradability, and good adsorption/degradation performance. Herein, a self-supporting CoFe2O4nanoparticles on 2D g-C3N4/2D loofah activated carbon (CoFe2O4/g-C3N4/BC) is successfully synthesized by simple hydrothermal method using loofah as carbon source and melamine as nitrogen source. The obtained CoFe2O4/g-C3N4/BC materials have a stable hierarchical sandwich structure with macroporous and mesoporous and a large surface area (189.52 m2/g), which can be used as an adsorbent/catalyst for the adsorption/degradation of organic pollutants. With these beneficial properties, the CoFe2O4/g-C3N4/BC material mediated peroxymonosulfate activation exhibits superior catalytic activity in the degradation of organic pollutants under ambient conditions. A model pollutant tetracycline (TC) can be rapidly degraded by 94.97 % within 25 min. The degradation efficiency was sustained at 88.21 % even after five operational cycles, with the cobalt metal leaching rate consistently below 50 μg/L. The inhibition experiment indicates that the main active species in the CoFe2O4/g-C3N4/BC + PMS system are SO4•−, HO•and 1O2, and the degradation of TC is achieved by the synergistic effect of free radical and non-radical pathways. This study provides a new perspective on the treatment of antibiotic wastewater via the sulfate radicals based-advanced oxidation processes (SR-AOPs).

Sodium-ion batteries (SIBs) have aroused wide attention because a large amount of sodium reserves has been proven to exist, acquiring less cost compared to lithium-ion batteries (LIBs). Besides, their chemical/electrochemical performances are quite similar to those of modern LIBs as well as they have extraordinary safety, playing a crucial role in large energy storage systems. However, the main challenge faced by SIB anode is the inherent low specific capacity, rapid capacity degradation, and slow ion diffusion dynamics, which means they need to be further designed to solve these problems. In this review, the recent research on the rational-designed anode materials with boosted sodium storage performance and controlled morphologies which lead to better electrochemical performance has been summarized. Further investigation of anode materials with enhanced specific capacity has been emphasized, providing references for the investigations of advanced SIBs.

Heteroatom-doped holey graphene hydrogels (HGHs) have attracted great interest owing to their remarkable porous structure, superior electrochemical performances, and prospective applications for supercapacitors. Herein, a simple and scalable approach to synthesize nitrogen, sulfur co-doped three-dimensional HGHs is developed using (NH4)2S2O8as the pore-making agent and N, S sources by a one-step hydrothermal reaction. In a 6 M KOH electrolyte, the optimized HGH-based asymmetric supercapacitor exhibits an exceptionally high specific capacitance of 354 F g–1at 1 A g–1, an excellent rate capability of 299 F g–1at 100 A g–1, and outstanding cycle stability (104% of initial capacity retention at 5 A g–1after 10,000 cycles). Additionally, the assembled HGH electrode supercapacitor possesses a high energy density of 21.14 Wh kg–1(449.95 W kg–1) in a 1 M Na2SO4electrolyte. The N, S heteroatom doping and hierarchical pore structure are ascribed to the superior electrochemical performance of HGHs. Therefore, the convenient and efficient method in the present work provides new ways into the preparation of heteroatom-doped HGHs for high-performance supercapacitors.

Developing efficient and cost-effective bifunctional catalytic electrodes is of great importance to water splitting. In this study, hybrid Ni/Ni(OH)2-coated NiCo2O4nanorods were grown on Ni foam (NF) by a facile growth–conversion–epitaxy approach. The epitaxial decoration of Ni/Ni(OH)2composite could increase the intrinsic activity of NiCo2O4/NF and enhance the charge-transfer rate. This self-standing hierarchical nanohybrid with unique surface chemistry and interface engineering exhibits an excellent electrocatalytic performance. The optimized Ni/Ni(OH)2-NiCo2O4/NF only requires overpotentials of 53 and 235 mV to reach a current density of 10 mA cm–2for HER and OER, respectively. The electrolyzer achieved 10 mA cm–2at a low cell voltage of 1.51 V for water splitting. This work offers a new perspective for rationally designing electrocatalytic materials by surface decoration.

Hierarchical tri-metal-based hollow nano/micro rod-on-rod arrays are vertically grown on Cu foam by the cation-exchanging and anion exchanging approaches. Such ordered porous architecture, providing multi metal center, regular interconnection of macropore channel, large electrochemical surface area, small charge-transfer resistance, efficient mass transport and electron transfer for overall water splitting in alkaline media. [Display omitted] • Tri-Metal-based Hollow Nanorods-On-Microrod Arrays are vertically grown on Cu foam. • The ordered porous structure provides large electrochemical surface area and effective mass transfer. • A 3D layered micro-nano electrode material was synthesized in situ for electrocatalysis of HER and OER. • The composition and structure of the electrocatalyst were modulated to improve the catalytic performance. Constructing ordered hierarchical porous electrocatalysts while maintaining their high efficiency and stability for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly desirable but still remains challenging. Herein, hierarchical tri-metal-based hollow nano/micro rod-on-rod array structures, including hydroxides and phosphates, are vertically grown on Cu foam by the cation-exchanging and anion exchanging approaches. Such ordered porous architecture, providing multi metal center, regular interconnection of macropore channel, large electrochemical surface area, small charge-transfer resistance, efficient mass transport and electron transfer for overall water splitting in alkaline media. These obtained hydroxide OER catalysts (CoMn LDH@Cu(OH) 2 /CF) and phosphide HER catalysts (CoMnP@Cu 3 P/CF) exhibited low onset potential, low Tafel slope, and prominent durability. Such excellent performance, ordered porous structure and simple preparation methods indicate that this study provides a new strategy for assembling promising catalysts for water splitting and other applications. [ABSTRACT FROM AUTHOR]

Crystal structure and morphology can be regulated by inducing the positioning growth of metal sulfide, which is an efficient strategy to improve the oxygen evolution activity of the anode. Herein, solid NiMoO4nanoplate arrays were used as cages to immobilize the metal source, and Mo doped NiSxis obtained by in situsolvothermal sulfuration reaction with polysulfide as the sulfur source. The electronic structure, conductivity, crystallographic phase and microscopic morphology of oxygen evolution catalysts could be controlled simultaneously by polysulfide induced solid metal oxide sulfidation, thereby greatly improving their electrocatalytic oxygen evolution activity. Benefiting from these, the prepared Mo doped nickel-sulfur electrodes show great performance toward the oxygen evolution reaction with overpotentials of 184 mV and 240 mV at current densities of 50 and 100 mA cm−2in alkaline electrolyte. This study provides a new pathway by polysulfide induced sulfidation based on solid metal oxide for developing metal sulfide electrode materials with high oxygen evolution reaction performance for overall water splitting.

Phenol is highly toxic and can cause damage to humans and the ecosystem even at low concentrations. Therefore, developing a rapid, sensitive and easy operated detection strategy still faces challenge. In this work, the covalent organic frameworks (COFs)-reinforced peroxidase-mimicking hybrid nanozyme was rationally designed by assembly COFs on magnetic Fe3O4@ZIF-8 nanozyme. The Fe3O4@ZIF-8 @COF hybrid nanozyme exhibited significant improved catalytic activity and can be developed as a rapid and sensitive phenol colorimetric sensor with ease operation. The core-shell structure and the crystallinity of the as-prepared hybrid nanozyme were characterized in detail by various analytical methods SEM, TEM, FT-IR, XRD and elemental mapping. The catalytic activity of Fe3O4@ZIF-8 @COF mimic enzyme was investigated in the presence of H2O2using 4-aminoantipyrine (4-AAP) as the substrate. The developed Fe3O4@ZIF-8 @COF hybrid nanozyme was applied to construct colorimetric sensor for phenol detection and the result presented high selectivity, excellent stability and good reusability with a wide linear range (6–350 μM), low detection limit (2 μM) and an advantageous response time (5 min). The designed catalyst makes the enhancement of peroxidase-like activity, which can be attributed to the unique core-shell structure with the inner catalytic site and the outer protection and enrichment COF shell. Therefore, this proposed colorimetric sensor with robust, stable and easy-recycled properties displayed excellent practical significance for the fast and sensitive detection of phenol in water environment.

Crystal structures and chemical states can be reconstructed by inducing the positioning growth of metal sulfide, which is an efficient strategy to enhance the oxygen evolution activity of an anode. In this paper, polysulfide (Poly(S-r-DIB))-induced S-doped hierarchical heterostructures Ni3S2/NiCo2S4were successfully grown on nickel foam (Ni3S2/NiCo2S4/NF) by an in situ solvothermal sulfuration reaction using polysulfide as the sulfur source. The unique hierarchical heterostructure and strong electron interaction in Ni3S2@NiCo2S4/NF increased the catalytic activity area and provided more mass transfer channels for electron transfer to facilitate water splitting. As-prepared Ni3S2/NiCo2S4/NF exhibits excellent electrocatalytic activity for oxygen evolution reaction (OER) with an ultralow overpotential of 330 mV to reach 100 mA cm–2and a small Tafel slope of 67.6 mV dec–1, which is superior to most reported nickel-based sulfide electrocatalysts. This study provides not only a new method for the design of hierarchical nanomaterials but also an efficient strategy to design efficient OER electrocatalysts by an in situ polysulfide confinement method.

Driven by the growing of electric vehicle, there is an unmet need to develop wide-range temperate management of Li-ion battery. Promising phase change materials (PCMs) with reinforced energy storage and conversion performance can cool battery by heat storage and heat battery by electro-thermal conversion. Herein, carbon hybrid aerogel by integrating MOF-derived carbon (MOFC) and graphene oxide (GO) aerogel was fabricated to encapsulate lauric acid as LA@MOF-C/GO PCM composite. Densely network of the hybrid aerogel works to enhance electrical/thermal conductivities while synergistic effect between MOF-C and GO helps to improve PCM loading capacity. Consequently, the PCM composite exhibited enhanced heat storage and electro-thermal conversion performances including low input voltage (2.2 V), high electro-thermal efficiency (90%), and enhanced enthalpy (140 J/g), thermal conductivity (1.35 W/mK) and shape-stability (10 °C above m.p.). The LA@MOF-C/GO composite worked efficiently to improve battery performance under environment temperature ranging from 45 °C to −20 °C, which shows great potential in thermal management of electric vehicle battery.

To develop a computer aided detection (CAD) system that improves diagnostic accuracy of intracranial hemorrhage on cerebral CT. A method for CT image segmentation of brain is proposed, with which, several regions that are suspicious of hemorrhage can be segmented rapidly and effectively. Extracting intracranial area algorithm is introduced firstly to extract intracranial area. Secondly, FCM is employed twice, we named it with TFCM. FCM is first employed to identify areas of intracranial hemorrhage. Finally, FCM is employed to segment the lesions. Experimental results on real medical images demonstrate the efficiency and effectiveness.

We present a simple method to produce superparamagnetic Fe3O4@Clays nanocomposites consisting of magnetic iron oxide nanoparticles orderly self-assembled on some restricted positions of nanoclays. The as-prepared Fe3O4@Clays have highly ordered structure, large surface area, and high magnetic sensitivity, as verified by transmission electron microscopy (TEM), IR spectroscopy, X-ray diffraction (XRD), nitrogen adsorption−desorption isotherms, and a vibrating sample magnetometer (VSM). Subsequently, the as-prepared Fe3O4@Clays treated with (3-aminopropyl)triethoxysilane are used as immobilization material. The conjugation of glucoamylase, hereby chosen as model enzyme, onto the amino-functionalized magnetic nanoparticles by using glutaraldehyde as a coupling reagent is further demonstrated and assessed based on its activity, kinetics, and thermal stability as well as reusability. Inspired by the structural character of enzyme (containing functional residues that are ideal reaction sites for the immobilization of enzymes once more), two novel regenerated strategies of supports are successfully developed to regenerate the carriers at the end of the life of the immobilized glucoamylase. The quality of glucoamylase immobilized on the regenerated supports is also defined by determining of the enzyme activity, kinetics, thermal stability, and reusability. The results indicate that the strategies for the regeneration of supports are viable. The applicability of the regenerated strategies of supports in the current study is relevant for the conjugation of other enzymes beyond glucoamylase. The regenerated strategies also offer an attractive and flexible alternative to regenerate other traditional supports at the end of the life of the immobilized enzyme.

Epidemiological and clinical data suggest that homocysteine (Hcy) may increase the risk of Alzheimer's disease, but the underlying mechanisms are elusive. To investigate the effect of Hcy on phosphorylation of τ, we injected Hcy into the lateral cerebral ventricle of rats. We found that level of the hyperphosphorylated τ at PHF-1 (Ser396404) and τ-1 (Ser198199202) epitopes was elevated prominently at 6, 9, and 12 h after the injection, and it was recovered to normal at 24 h. Simultaneously, the level of protein phosphatase-2A catalytic subunit (PP-2Ac) was reduced markedly as compared with control. These results imply that Hcy may induce hyperphosphorylation of τ with PP-2Ac involved mechanism.

We have developed an ultrasensitive bienzyme-substrate-recycle enzyme-linked immunosorbent assay for the measurement of Alzheimer's disease (AD) abnormally hyperphosphorylated tau in cerebrospinal fluid (CSF). The assay, which recognizes attomolar amounts of tau, is ∼400 and ∼1300 times more sensitive than conventional enzyme-linked immunosorbent assay in determining the hyperphosphorylated tau and total tau, respectively. With this method, we measured both total tau and tau phosphorylated at Ser-396/Ser-404 in lumbar CSFs from AD and control patients. We found that the total tau was 215 ± 77 pg/ml in cognitively normal control (n= 56), 234 ± 92 pg/ml in non-AD neurological (n= 37), 304 ± 126 pg/ml in vascular dementia (n= 46), and 486 ± 168 pg/ml (n= 52) in AD patients, respectively. However, a remarkably elevated level in phosphorylated tau was only found in AD (187 ± 84 pg/ml), as compared with normal controls (54 ± 33 pg/ml), non-AD (63 ± 34 pg/ml), and vascular dementia (72 ± 33 pg/ml) groups. If we used the ratio of hyperphosphorylated tau to total tau of ≥0.33 as cutoff for AD diagnosis, we could confirm the diagnosis in 96% of the clinically diagnosed patients with a specificity of 95%, 86%, 100%, and 94% against nonneurological, non-AD neurological, vascular dementia, and all of the three control groups combined, respectively. It is suggested that the CSF level of tau phosphorylated at Ser-396/Ser-404 is a promising diagnostic marker of AD.

Countering the problem of expediting the peroxymonosulfate oxidation, porous carbon nanofibers loaded with copper-cobalt bimetallic particles (CuCo@ CNF) were synthesized by a three-step process, including electrospinning, solvothermal reaction and carbonization. The well-crystallized copper-cobalt nanoparticles with an average particle size of 322nm, which were evenly decorated on the surface of the porous carbon nanofibers with a relatively high specific surface area (average value= 161.281 m2g-1), as examined by XRD, SEM, TEM, and BET. The saturation magnetization of CuCo@CNF measured by VSM is 26.5emug-1, suggesting its easy separation due to magnetic property. In CuCo@CNF-PMS system, the removal rate of Acid Red 1 (AR1) as a model pollutant can achieved 99.0% and 98.1% in the 1stand 7thrun, respectively. Metal leaching after reaction were reduced for CuCo@CNF when compared with the respective CNF supported Co or Cu catalysts. In addition, the catalytic degradation mechanism of AR1 was elucidated by detecting reactive oxygen species (ROS: SO•4-, •OH and 1O2) alongside the reaction. AR1 can even be mineralized through CuCo@CNF-PMS, evidenced by TOC removal rate of 55.5% within 20min. These results suggest that the as-synthesized catalyst is an attractive candidate for the treatment of wastewater with recalcitrant organic pollutants.

The development of highly efficient, economical, and sustainable electrocatalysts based on non‐noble metals for hydrogen evolution reaction (HER) is of vital significance for large‐scale renewable energy storage. Herein, an effective synthetic strategy for the construction of MoO2nanoflowers decorated with metallic Cu/Cu2O nanoparticles (NPs) on Ni foam (NF) (Cu2O/MoO2@Cu/NF) with a simple two‐step method is reported. The prepared Cu2O/MoO2@Cu/NF as an electrocatalyst exhibits outstanding reactivity and remarkable stability in alkaline solution. The onset overpotential of Cu2O/MoO2@Cu/NF approaches 0 V. An overpotential as low as 32 mV is obtained to afford a current density of 10 mA cm−2, comparable with Pt/C catalysts. The Tafel slope is low at 40 mV dec−1as well. The involvement of zero‐valent Cu greatly reduces the resistance. The well‐dispersed Cu/Cu2O NPs on the sphere‐like MoO2nanoflowers exaggerate the surface area. The ringent channels provide the fast release of evolved bubbles. Furthermore, the enhanced conductivity and large surface area lead to significant activity in HER. Herein, a novel design and facile synthesis of a highly efficient electrocatalyst with catalytic activity that is comparable to a Pt/C catalyst is provided. Cu/Cu2O nanoparticles–decorated MoO2nanoflowers exhibit outstanding reactivity with a low overpotential of 32 mV at 10 mA cm−2due to the larger surface area, enhanced conductivity, and strong electron interaction.