Latest ArticlesEpoxy resin is widely used in electronic packaging due to its exceptional performance, particularly the low-temperature curable thiol/epoxy system, which effectively minimizes thermal damage to sensitive electronic components. However, the majority of commercial thiol curing agents contain hydrolysable ester bonds and lack rigid structures, which induces most of thiol/epoxy systems still suffering from unsatisfactory heat resistance and hygrothermal resistance, significantly hindering their application in electronic packaging. In this study, we synthesized a tetrafunctional thiol compound, bis[3-(3-sulfanylpropyl)-4-(3-sulfanylpropoxy)phenyl]sulfone (TMBPS) with rigid and ester-free structures to replace traditional commercial thiol curing agents, pentaerythritol tetra(3-mercaptopropionate) (PETMP). Compared to the PETMP/epoxy system, the TMBPS/epoxy system exhibited superior comprehensive properties. The rigid structures of bisphenol S-type tetrathiol enhanced the heat resistance and mechanical properties of TMBPS/epoxy resin cured products, outperforming those of PETMP/epoxy resin cured products. Notably, the glass transition temperature of TMBPS/epoxy resin cured products was 74.2 ℃ which was 11.8 ℃ higher than that of PETMP cured products. Moreover, the ester-free structure in TMBPS contributed to its enhanced resistance to chemicals and hygrothermal conditions. After undergoing 1000 h of high-temperature and high-humidity aging, the tensile strength and adhesion strength of TMBPS-cured products were 73.33 MPa and 3.39 MPa, respectively exceeding 100% and 40% of their initial values, while PETMP-cured products exhibited a complete loss of both tensile strength and adhesion strength. This study provides a strategy for obtaining thermosetting polymers that can be cured at low temperatures and exhibit excellent comprehensive properties.
Flexible zinc-ion batteries (FZIBs) have been acknowledged as a potential cornerstone for the future development of flexible energy storage, yet conventional FZIBs still encounter challenges, particularly concerning performance failure at low temperatures. To address these challenges, a novel anti-freezing leather gel electrolyte (AFLGE-30) is designed, incorporating ethanol as a hydrogen bonding acceptor. The AFLGE-30 demonstrates exceptional frost resistance while maintaining favorable flexibility even at −30 ℃; accordingly, the battery can achieve a high specific capacity of about 70 mAh/g. Cu//Zn battery exhibits remarkable stability at room temperature, retaining ~96% efficiency after 120 plating/stripping cycles at 1 mA/cm2. Concurrently, the Zn//Zn symmetric batteries demonstrate a lifespan of 4100 h at room temperature, which is attributed to the enhancement of Zn2+ deposition kinetics, restraining the formation of zinc dendrites. Furthermore, FZIBs exhibit minimal capacity loss even after bending, impacting, or burning. This work provides a promising strategy for designing low-temperature-resistant FZIBs.
Spin-orbit coupling (SOC) plays a vital role in determining the ground state and forming novel electronic states of matter where heavy elements are involved. Here, the prototypical perovskite iridate oxide SrIrO3 is investigated to gain more insights into the SOC effect in the modification of electronic structure and corresponding magnetic and electrical properties. The high pressure metastable orthorhombic SrIrO3 is successfully stabilized by physical and chemical pressures, in which the chemical pressure is induced by Ru doping in Ir site and Mg substitution of Sr position. Detailed structural, magnetic, electrical characterizations and density functional theory (DFT) calculations reveal that the substitution of Ru for Ir renders an enhanced metallic characteristic, while the introduction of Mg into Sr site results in an insulating state with 10.1% negative magnetoresistance at 10 K under 7 T. Theoretical calculations indicate that Ru doping can weaken the SOC effect, leading to the decrease of orbital energy difference between J1/2 and J3/2, which is favorable for electron transport. On the contrary, Mg doping can enhance the SOC effect, inducing a metal-insulator-transition (MIT). The electronic phase transition is further revealed by DFT calculations, confirming that the strong SOC and electron-electron interactions can lead to the emergence of insulating state. These findings underline the intricate correlations between lattice degrees of freedom and SOC in determining the ground state, which effectively stimulate the physical pressure between like structures by chemical compression.
Nickel-rich cathode materials have received widespread attention due to their high energy density. However, the poor rate capability and inferior cycle stability seriously hinder their large-scale application. The traditional co-precipitation method for preparing them has a long process and easily arises agglomeration leading to inhomogeneous element distribution. Here, a novel precursor containing Li element was prepared by ultrafast spray pyrolysis (SP) in 3–5 s. Then the precursor was used to synthesize pristine LiNi0.9Co0.05Mn0.05O2 (NCM90) and 1% Mg modified LiNi0.9Co0.05Mn0.05O2 (NCM90-Mg1). This method gets rid of mixing Li/Mg source and the precursor prepared by common co-precipitation, thus could achieve homogeneous lithiation and Mg2+ doping. The cell parameter c is expanded, and the cation disorder is reduced after Mg2+ doping. Furthermore, the harmful H2-H3 phase transition in NCM90-Mg1 is also well suppressed. As a result, the obtained NCM90-Mg1 shows better electrochemical performance than NCM90. Within 2.8–4.3 V (25 ℃), the specific discharge capacity of NCM90-Mg1 at 5 C is as high as 169.1 mAh/g, and an outstanding capacity retention of 70.0% (10.0% higher than NCM90) can be obtained after 400 cycles at 0.5 C. At 45 ℃, a capacity retention of 81.9% after 100 cycles at 1 C is recorded for NCM90-Mg1. Moreover, the NCM90-Mg1 also exhibits superior cycle stability when cycled at high cut-off voltage (4.5 V, 25 ℃), possessing the capacity retention of 79.2% after 200 cycles at 1 C. Therefore, SP can be proposed as a powerful method for the preparation of multi-element materials for next-generation high energy density LIBs.
The sluggish reaction kinetics of the oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) remain obstacles to the commercial promotion of water splitting and direct methanol fuel cells. Considering the vital role of noble metals in electrocatalytic activity, this work focuses on the rational synthesis of Ni-noble metal composite nanocatalysts for overcoming the drawbacks of high cost and susceptible oxidized surfaces of noble metals. The inherent catalytic activity is improved by the altered electronic structure and effective active sites of the catalyst induced by the size effect of noble metal clusters. In particular, a series of Ni-noble metal nanocomposites are successfully synthesized by partially introducing noble metal into Ni with porous interfacial defects derived from Ni-Al layered double hydroxide (LDH). The Ni10Pd1 nanocomposite exhibits high OER catalytic activity with an overpotential of 0.279 V at 10 mA/cm2, surpassing Ni10Ag1 and Ni10Au1 counterparts. Furthermore, the average diameter of Pd clusters gradually increases from 5.57 nm to 44.44 nm with the increased proportion of doped Pd, leading to the passivation of catalytic activity due to the exacerbated surface oxidation of Pd in the form of Pd2+. After optimization, Ni10Pd1 delivers significantly enhanced OER and MOR electroactivities and long-term stability compared to that of Ni2Pd1, Ni1Pd1 and Ni1Pd2, which is conducive to the effective utilization of Pd and alleviation of surface oxidation.
Urea-assisted water electrolysis offers a promising route to reduce energy consumption for hydrogen production and meanwhile treat urea-rich wastewater. Herein, we devised a shear force-involved polyoxometalate-organic supramolecular self-assembly strategy to fabricate 3D hierarchical porous nanoribbon assembly Mn-VN cardoons. A bimetallic polyoxovanadate (POV) with the inherent structural feature of Mn surrounded by [VO6] octahedrons was introduced to trigger precise Mn incorporation in VN lattice, thereby achieving simultaneous morphology engineering and electronic structure modulation. The lattice contraction of VN caused by Mn incorporation drives electron redistribution. The unique hierarchical architecture with modulated electronic structure that provides more exposed active sites, facilitates mass and charge transfer, and optimizes the associated adsorption behavior. Mn-VN exhibits excellent activity with low overpotentials of 86 mV and 1.346 V at 10 mA/cm2 for hydrogen evolution reaction (HER) and urea oxidation reaction (UOR), respectively. Accordingly, in the two-electrode urea-assisted water electrolyzer utilizing Mn-VN as a bifunctional catalyst, hydrogen production can occur at low voltage (1.456 V@10 mA/cm2), which has the advantages of energy saving and competitive durability over traditional water electrolysis. This work provides a simple and mild route to construct nanostructures and modulate electronic structure for designing high-efficiency electrocatalysts.
Herein, we report the design and synthesis of alternating donor-acceptor nanorings [3]C-NA and [4]C-NA, along with a reference linear molecule [3]L-NA, via electrochemical oxidation-induced reductive elimination of alkynyl platinum(Ⅱ) complexes. Unlike [3]L-NA, which exhibits charge defects at its end-groups, the cyclic structures of [3]C-NA and [4]C-NA facilitate enhanced electron delocalization, enabling efficient charge transfer in low-polarity toluene. In the polar solvent dichloromethane (DCM), the increased flexibility of [4]C-NA promotes intramolecular charge transfer and suppresses charge recombination. The observed faster intramolecular charge transfer and slower charge recombination rates in these nanoring acceptor materials suggest their potential for improving the power conversion efficiency of organic solar cells, providing valuable insights for the design of nanoring acceptor materials.
The significance of axial chiral compounds in asymmetric organic catalysis, functional materials, and pharmaceutical useful molecules has encouraged advancements in the atroposelective synthesis of such compounds. Herein, we report the first atroposelective construction of axially chiral N-aryl benzimidazoles catalyzed by a polymer-supported chiral phosphoric acid. A varied library of atropisomers has been synthesized in 30%-96% yield with 58%-98% enantiomeric excess (ee) under a straightforward reaction setup (without the use of molecular sieves). Notably, even after 12 cycles, the immobilized catalyst maintained its reactivity and selectivity (TON > 540).
Advanced oxidation processes (AOPs) governed by peroxide activation to produce highly oxidative active species have been extensively explored for environmental remediation. Nevertheless, the low diffusion rates, inadequate interactions of the reactants, and limited active site exposure hinder treatment efficiency. Porous carbocatalysts with high specific surface area, tunable pore size, and programmable active sites demonstrate outstanding performance in activating diverse types of peroxides to generate active species for treatment of aqueous organic pollutants. The pore-rich structures enhance reaction kinetics for peroxide activation by facilitating diffusion of the reactants and their interactions. Additionally, the structural flexibility of porous structures favors the accommodation of highly dispersed metal species and allows for precise tuning of the microenvironment around the active sites, which further enhances the catalytic activity. This review critically summarizes the recent research progress in the applications of engineered porous carbocatalysts for peroxide activation and outlines the prevailing pore construction methods in carbocatalysts. Moreover, engineering strategies to regulate the mass transfer efficiency and fine-tune the microenvironment around the active sites are systematically addressed to enhance their catalytic peroxide activation performances. Challenges and future research opportunities pertaining to the design, optimization, mechanistic investigation, and practical application of porous carbocatalysts in peroxide activation are also proposed.
Regioselevtive functionalization of perylene diimides (PDIs) at bay area often requires multistep synthesis and strenuous recrystallization. Direct bromination of perylene diimides only afford the 1, 6 and 1, 7-regioisomers. More importantly, the 1, 6-dibromo regioisomers could only be separated by preparative HPLC. Herein, we report a promising strategy for constructing Janus backbone of BN-doped perylene diimide derivatives. This Janus-type configuration results in the unique regioselective functionalization of BN-JPDIs, which yields exclusively the 1, 6-regioisomers. Further investigation shows that the Janus-type configuration leads to a net dipole moment of 1.94 D and intramolecular charge transfer, which causes substantial changes on the optoelectronic properties. Moreover, the single crystal organic field-effect transistors based on BN-JPDIs exhibit electron mobilities up to 0.57 cm2 V−1 s−1, showcasing their potential as versatile building block towards high-performance n-type organic semiconductors.
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