Latest ArticlesSelective oxidation of olefin to epoxides is an important reaction in industry, however, developing heterogeneous catalysts to achieve the effective catalysis for this reaction under O2 atmosphere at room temperature is challenging but highly desired. In this work, two novel 2D cobalt metal-organic complexes, namely [Co(L)(5-HIP)]·2H2O (Co-MOC-1) and [Co(L)(BTEC)0.5]·H2O (Co-MOC-2) (L = (E)-4,4′-(ethene-1,2-diyl)bis(N-(pyridin-3-yl)benzamide; 5-H2HIP = 5-hydroxyisophthalic acid; H4BTEC = pyromellitic acid) were designed and synthesized through hydrothermal method, which exhibited different metal coordination modes (4-coordinate and 5-coordinate, respectively) and 2D layer structures directed by different carboxylates co-ligands. Two Co-MOCs can serve as heterogeneous catalysts for the selective oxidation of olefins to epoxides at room temperature using O2 as oxidant. Furthermore, a higher catalysis activity of Co-MOC-1 than Co-MOC-2 (96.7% vs. 90.2% yield of 1,2-epoxycyclooctane) was observed, which may be attributed to the coordination unsaturated Co centers, the less coordination number and larger interlayer spacing of Co-MOC-1.
In response to the increasing demand of ethylene, electrochemical ethane nonoxidative dehydrogenation (EENDH) to ethylene by protonic ceramic electrolysis cells (PCECs) is developed. However, existing anode materials exhibit poor proton conductivity and limited catalytic activity. Herein, a novel Sr1.95Fe1.4Co0.1Mo0.4Zr0.1O6-δ (SFCMZ) anode is prepared as PCECs anode for EENDH. Zr doping increases the oxygen vacancies and enhances the proton conductivity of SFCMZ. Moreover, an alloy-oxide heterostructure (CoFe@SFCMZ) is formed through in-situ exsolution of CoFe alloy nanoparticles under reduction conditions, generating abundant oxygen vacancies and improving its catalytic activity. CoFe@SFCMZ cell achieves an electrolysis current density of 0.87 A/cm2 at 700 ℃ under 1.6 V, with an ethane conversion rate of 34.22% and corresponding ethylene selectivity of 93.4%. These results demonstrate that CoFe@SFCMZ anode exhibits excellent electrocatalytic activity, suggesting promising applications for EENDH.
Developing efficient electrocatalysts for oxygen evolution reaction (OER) is imperative to enhance the overall efficiency of electrolysis systems and rechargeable metal-air batteries operating in aqueous solutions. High-entropy materials, featured with their distinctive multi-component properties, have found extensive application as catalysts in electrochemical energy storage and conversion devices. However, synthesizing nanostructured high-entropy compounds under mild conditions poses a significant challenge due to the difficulty in overcoming the immiscibility of multiple metallic constituents. In this context, the current study focuses on the synthesis of an array of nano-sized high entropy sulfides tailored for OER via a facile precursor pyrolysis method at low temperature. The representative compound, FeCoNiCuMnSx, demonstrates remarkable OER performance, achieving a current density of 10 mA/cm2 at an overpotential of merely 220 mV and excellent stability with constant electrolysis at 100 mA/cm2 for over 400 h. The in-situ formed metal (oxy)hydroxide has been confirmed as the real active sites and its exceptional performance can be primarily attributed to the synergistic effects arising from its multiple components. Furthermore, the synthetic methodology presented here is versatile and can be extended to the preparation of high entropy phosphides, which also present favorable OER performance. This research not only introduces promising non-noble electrocatalysts for OER but also offers a facile approach to expand the family of nano high-entropy materials, contributing significantly to the field of electrochemical energy conversion.
Agrochemicals, especially plant growth regulators (PGRs), are extensively used to modulate endogenous phytohormone signals in small quantities, significantly influencing plant growth and development. Plant hormones typically exhibit diverse chemical structures, with common examples including indole rings, terpenoid frameworks, adenine motifs, cyclic lactones, cyclopentanones, and steroidal compounds, which are extensively employed in pesticides. This article explores the interactions and biological activities of small molecules on proteins, enzymes, and other reactive sites involved in the biosynthesis, metabolism, transport, and signal transduction pathways of various plant hormones. Additionally, it analyzes the structure-activity relationships (SARs) of pesticides incorporating these structural motifs to elucidate the relationship between active fragments, pharmacophores, and targets, highlighting the characteristics of potent small molecules and their derivatives. This comprehensive review aims to provide novel perspectives for the development and design of pesticides, offering valuable insights for researchers in the field.
PVDF-based nanocomposites have gained significant focus in capacitors for their excellent dielectric strength, its multi-scale structural inhomogeneity is the bottleneck for improving the energy storage performance. Here, the composite components are optimized by the matrix modification, BST (Ba0.6Sr0.4TiO3) ceramic fibrillation and surface coating. A series of PVDF/polymethyl methacrylate/lysozyme@BST nanofibers with continuous gradient distribution (PF-M/mBST nf-g) are prepared by the concentration gradient-biaxial high-speed electrospinning. The finite element simulation and experiment results indicate that the continuous gradient structure is favorable for the microstructure and inhomogeneity of the electric field distribution, significantly increasing the breakdown strength (Eb) and the permittivity (εr), as well as effectively suppressing the interfacial injected charge and leakage current. As a result, the energy storage density (Ue) of 23.1 J/cm3 at 600 MV/m with the charge-discharge efficiency (η) of 71% is achieved compared to PF-M (5.6 J/cm3@350 MV/m, 65%). The exciting energy storage performance based on the well-designed PF-M/mBST nf-g provides important information for the development and application of polymer nanocomposite dielectrics.
Secondary trauma, resulting in undesirable injury and bleeding during wound dressing treatment, which will cause the treatment of chronic wounds ineffective. The medical cotton gauzes often bring strong adhesion due to the exudates absorbed and clots formed. Conversely, the easily detachable wound dressings neglect the wound seepage management, rendering them ineffective in facing the complexities of chronic wounds. To address this challenge, we propose a novel draining anti-adhesion dressings (DAD) by constructing the hydrophilic microchannels array on the superhydrophobic dressing. The superhydrophobic areas facilitate stable wound fluid repellence leading to achieve the anti-adhesion (18.7% detachment energy of cotton) and the microchannel array ensures the transportation of excess exudates (>92%) by the capillary force. Notably, our dressing demonstrates a significant healing-promoting in a chronic wound model in rats. The development of such dressings holds promise for advancing wound care practices and addressing the unique challenges posed by chronic wounds, offering a valuable solution for improved clinical outcomes.
Natural hydraulic lime (NHL) has garnered increasing attention for its sustainable and suitable performance in the field of historical building restoration. However, the prolonged hardening time and sluggish hydration rate of NHL influence the workability, strength development, and durability of construction structures in which it is used. In this study, nano-metakaolin (NMK) was applied as a highly reactive supplementary cementitious material (SCM) for NHL-based mortars to enhance their properties with various ratios. Meanwhile, the effects of NMK and its related enhancement mechanism on the physical properties and chemical structures of NHL composites were systematically investigated, mainly involving the modifications in their microstructure, chemical composition, and C-S-H structure. Results demonstrated that NMK-modified samples showed distinct and superior properties to pure NHL sample, such as shorter initial/final setting times (15.1%–49.1%, 27.1%–50.0%), and higher compactness (67.8%–81.4%, 38.1%–44.8%), lower shrinkage (25.0%–56.3%, 12.5%–25.0%), enhanced compressive strength (404.5%–546.0%, 180.8%–354.1%) and flexural strength (227.5%–351.1%, 59.9%–125.7%) for both early and late curing times (7 and 28 days). The inclusion of NMK not only acts as a fine filler, but also promotes NHL's hydrate rate by its super high pozzolanic activity, thus optimizing the pore structures and increasing the content and the average silicate chain length of hydration gel in NHL. Overall, this study can contribute to a deeper understanding of the enhancement mechanism of NMK on the physical properties and chemical structures of NHL from a meso/microscopic perspective, with a view to broadening NHL's potential applications.
Manipulating catalyst structures to control product selectivity while maintaining high activity presents a considerable challenge in CO2 hydrogenation. Combining density functional theory calculations and microkinetic analysis, we proposed that graphene-supported isolated Pt atoms (Pt1/graphene) and Pt2 dimers (Pt2/graphene) exhibited distinct selectivity in CO2 hydrogenation. Pt1/graphene facilitated the conversion of CO2 into formic acid, whereas Pt2/graphene favored methanol generation. The variation in product selectivity arose from the synergistic interaction of Pt2 dimers, which facilitated the migration of H atoms between two Pt atoms and promoted the transformation from *COOH intermediates to *C(OH)2 intermediates, altering the reaction pathways compared to isolated Pt atoms. Additionally, an analysis of the catalytic activities of three Pt1/graphene and three Pt2/graphene structures revealed that the turnover frequencies for formic acid generation on Pt1ⅱ/graphene and methanol generation on Pt2ⅰ/graphene were as high as 744.48 h-1 and 789.48 h-1, respectively. These values rivaled or even surpassed those previously reported in the literature under identical conditions. This study provides valuable insights into optimizing catalyst structures to achieve desired products in CO2 hydrogenation
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