Latest ArticlesPVDF-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.
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.
Selective 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.
The exploitation of organic-inorganic hybrid perovskites (OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the influence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)2(PbBr4)]n (BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)2(PbBr4)]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120 ℃. The increase in temperature leads to a decrease in the PbBr6 octahedral distortion in the crystal structure, an increase in hydrogen bonding between the (BIZ-H)+ cation and the (PbBr4)n2n- layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.
Carbon materials have long been a subject of study, offering diverse properties based on their hybridized structures. Except sp2-hybridized graphene and carbon nanotubes, the focus on sp1-hybridized carbon chains has garnered significant interest due to its unique predicted properties, despite limitations in research and development stemming from its high reactivity. This comprehensive review summaries recent advancements in synthetic methodologies and characterization of the sp1-hybridized carbon chains, encompassing linear carbon chains and cyclo[n]carbons. The review traces significant milestones in synthesis and offers a thorough overview of various properties on linear and cyclic carbon chains, from their initial discovery to recent development. The advancing synthetic methods have led to practical breakthroughs, transitioning theoretical concepts into tangible carbon-chain materials. However, challenges persist in achieving controlled and scalable preparation due to the high reactivity associated with sp1-hybridization. Future research prospects focus on fundamental studies, such as exploring the transition length from polyyne to carbyne and experimentally determining the properties of single carbon chains. This review underscores both the progress made and the compelling avenues for future exploration in the dynamic field of sp1-hybridized carbon chains.
Carbon materials are considered as prospective anode candidates for potassium ion batteries (PIBs). However, the low-rate capability is hampered by slow K+ diffusion kinetics and obstructed electron transport of carbon-based anodes. In this work, calcium d-gluconate derived mesoporous carbon nanosheets (CGC) were interpenetrated into the architecture of reduced graphene oxides (RGO) to form the composites of two-dimensional (2D)/2D graphene/mesoporous carbon nanosheets (RGO@CGC). CGC as a rigid skeleton can prevent the graphene layers from restacking and maintain the structural stability of the 2D/2D carbon composites of RGO@CGC. The mesopores in CGC can shorten the path of ion diffusion and facilitate the penetration of electrolytes. RGO possesses the high surface-to-volume ratio and superior electron transport capability in the honeycomb-like 2D network consisting of sp2-hybridized carbon atoms. Especially, the π-π stacking interaction between CGC and RGO enhances stable composite structure formation, expedites interlayer-electron transfer, and establishes three-dimensional (3D) ion transportation pathways. Owing to these unique structure, RGO@CGC exhibits fast and stable potassium storage capability. Furthermore, the effects of binders and electrolytes on the electrochemical performance of RGO@CGC were investigated. Finally, Prussian blue was synthesized as a positive electrode to explore the possibility of RGO@CGC as a full battery application.
Exploring the intrinsic reasons for the dynamic reconstruction of catalysts during electrocatalytic reactions and their impact on activity enhancement still face severe challenges. Herein, the bifunctional catalyst Ru/V-CoO/CP with doping strategy and heterostructure was synthesized for overall water splitting. The Ru/V-CoO exhibits excellent activity for HER and OER with low overpotentials of 49, 147 mV at a current density of 10 mA/cm2 in 1.0 mol/L KOH, respectively. The assembled electrolytic cell just needs voltages of 1.47 and 1.71 V to achieve 10 and 350 mA/cm2 current density under the same conditions and delivers an outstanding stability for over 100 h, which is far superior to the commercial RuO2Pt/C cell. Experimental and theoretical results indicate that the doping of V species and the formation of heterostructures lead to charge redistribution. More importantly, the leaching of V species induces electron transfer form Co to O and then Ru through the Co-O-Ru electron bridge, optimizes the adsorption strength of the key intermediate, thereby reducing the free energy barrier of the rate-determining step and improving catalytic activity. This work proposes an effective strategy of using cation dissolution to induce electron transfer through the electron bridge and thus regulate the electronic structure of catalysts, providing new ideas for the design and development of efficient and stable electrocatalysts.
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.
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