Graphitic Carbon Nitride (g-C3N4): An Interface Enabler for Solid-State Lithium Metal Batteries

Solid-state Li metal batteries (SSLMBs) have attracted considerable interests due to their promising energy density as well as high safety. However, the realization of a well-matched Li metal/solid-state electrolyte (SSE) interface remains challenging. Herein, we report g-C₃N₄ as a new interface enabler. We discover that introducing g-C₃N₄ into Li metal can not only convert the Li metal/garnet-type SSE interface from point contact to intimate contact but also greatly enhance the capability to suppress the dendritic Li formation because of the greatly enhanced viscosity, decreased surface tension of molten Li, and the in situ formation of Li₃N at the interface. Thus, the resulting Li-C₃N₄|SSE|Li-C₃N₄ symmetric cell gives a significantly low interfacial resistance of 11 Ω cm² and a high critical current density (CCD) of 1500 μA cm⁻². In contrast, the same symmetric cell configuration with pristine Li metal electrodes has a much larger interfacial resistance (428 Ω cm²) and a much lower CCD (50 μA cm⁻²).     

Crystallization-Induced Reversal from Dark to Bright Excited States for Construction of Solid-Emission-Tunable Squaraines

Squaraines (SQs) with tunable emission in the solid state is of great importance for various demands; however a remaining challenge is emission quenching upon aggregation. Herein, a unique SQ, named as CIEE-SQ, is designed to exhibit strong emission in crystal, undergoing crystallization-induced reverse from dark ¹(n+σ,π*) to bright ¹(π,π*) excited states. Such an excited state of CIEE-SQ can be subtly tuned by molecular conformation changes during the unexpected temperature-triggered single-crystal to single-crystal (SCSC) reversible transformation. Furthermore, co-crystallization between CIEE-SQ and chloroform largely stabilize the ¹(π,π*) state, enhancing the transition dipole moment and decreasing the reorganization energy to boost the fluorescence, which is promising in data encryption and decryption.     

An Extra-Large-Pore Pure Silica Zeolite with 16×8×8-Membered Ring Pore Channels Synthesized using an Aromatic Organic Directing Agent

Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q⁴) and unusual three-connected (Q³) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents.     

单层类水滑石纳米片的可控合成及规模生产展望

水滑石(LDHs)是一种阴离子黏土材料,由于其主体层板厚度的可调性,使其在光/电催化、电池、超级电容器、传感器以及生物医药等领域都具有广泛应用。降低层厚至单层可使材料的物理化学性质发生根本改变,从而优化催化性能。近期研究表明,利用自上而下,自下而上的方法,可以实现单层LDHs类材料的合成,但是受限于产量(g级)以及成本设备等问题,目前规模化制备高质量单层LDHs类材料还没有工业案例。成核晶化隔离法是目前唯一规模化合成纳米LDHs的工业化方法,具有成本低,产量可吨级放大等优点。本综述从合成方法、表征手段、应用三个角度讨论了单层及超薄LDHs的精准调控,详细论述了近期关于单层及超薄LDHs合成突破以及LDHs的规模化生产进展,并对其性能进行了总结,为后续设计高性能单层LDHs提供思路。     

“抑制-萃取”法从含铁酸溶液中选择性提钒

酸法浸出石煤提钒因具有环保、金属收率高的特点而备受关注,但同时进入母液的铁(高含量的Fe³⁺)严重影响了钒的富集和产品生产。 对此,本文提出一种基于“抑制-萃取”效应的钒/铁分离混合萃取体系(P507(2-乙基己基磷酸-单2-乙基己基酯)+ N235(三辛/癸烷基叔胺)+磺化煤油),并详细研究了各因素对钒铁分离和钒富集的影响规律。 结果表明,P507是钒铁萃取的主体,N235不具萃Fe³⁺能力,是产生抑制铁萃取的关键因素,其浓度越高铁萃取率越低;对于酸度较高(pH≤0.4)的原料液钒/铁的分离效果仍较好,这表明了该“抑制-萃取”混合萃取体系对高酸度浸出液钒/铁分离的适用性。 采用氨水从负载有机相中反萃取钒铁,当氨水浓度为6 mol/L时钒的反萃率99%以上,25 ℃,V(有机相)∶V(水相)=2∶1时的反萃液中钒质量浓度14.73 g/L,铁质量浓度小于0.022 g/L,m(V)/m(Fe)=669.5。 该“抑制-萃取”法分离钒/铁操作简单、经济高效,极具工业化前景。     

正相高效液相色谱法分析壬基环己醇聚氧乙烯醚中残留壬基环己醇

壬基环己醇聚氧乙烯醚(NCEO_n)是非环境友好型壬基酚聚氧乙烯醚(NPEO_n)潜在的升级换代产品。 本文采用正相高效液相色谱法(NP HPLC)测定产品中残存壬基环己醇(NC),用Weilbull法测定其中聚乙二醇(PEG)含量,用电喷雾电离质谱法评价聚氧乙烯(PEO)多分散指数(PDI),以此鉴定NCEO_n的品质。 为了建立快速分析NCEO_n产品中NC含量的方法,以满足跟踪检测的需求,本文筛选了反相HPLC和NP HPLC两类5种方法,并进行比较和初步条件优化,确定了用Inertsil NH₂色谱柱和示差折光检测器以及乙酸乙酯为洗脱液的NP HPLC法定量分析NC,方法的回收率为91.77%～107.6%,相对标准偏差为4.46%,最低检测限为9.8 μg/mL。 经测定,NCEO₇和NCEO₉产品中NC的残留量分别为0.158%和0.139%,PEG质量分数为7.1%和7.3%,PDI为85.0%和88.6%,证实NCEO_n产品具有NC残留量少、PEG含量低和产品PEO窄分布特征,具有在化妆品或个人洗护用品等民用产品中替代NPEO_n的潜能。     

两种形貌纳米Fe2O3对TKX-50热分解的催化性能研究

Energy components used in solid rocket propellants are beneficial for improving the energy performance, and their thermal decomposition characteristics significantly affect the combustion properties of the propellants. As a kind of energetic material with both high energy and low sensitivity (impact and friction), 5, 5'-bistetrazole-1, 1'-diolate (TKX-50) can effectively improve the energy and safety characteristics of solid propellants. Burning catalyst is another important component of solid propellants, which can significantly improve the burning rate of the propellant and reduce the pressure exponent. Among various burning catalysts, nanoscale transition metal oxides can promote the thermal decomposition of the energetic component, thus enhancing the combustion properties of the solid propellant. However, the catalytic effects of nanoscale transition metal oxides with different morphologies on the thermal decomposition of TKX-50 have rarely been studied. Based on the excellent catalytic activity of Fe₂O₃ for TKX-50 thermal decomposition, nano-Fe₂O₃ particles with spherical and tubular microstructures were used for TKX-50 thermal decomposition. The Fe₂O₃ nanoparticles were successfully fabricated via the solvothermal method and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. The XRD, FT-IR, and XPS results confirmed the successful fabrication of spherical and tubular Fe₂O₃ samples. The SEM and TEM images showed that the spherical Fe₂O₃ samples are composed of agglomerated Fe₂O₃ nanoparticles with an average particle size of 110 nm. In addition, the average diameter and length of hollow tubular Fe₂O₃ nanoparticles are 120 nm and 200 nm, respectively. The catalytic activities of spherical and tubular Fe₂O₃ for TKX-50 decomposition were studied by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) methods. The DSC and TG-DTG curves showed that both tubular and spherical Fe₂O₃ could effectively promote TKX-50 thermal decomposition. The first thermal decomposition peak temperature (T_FDP) of TKX-50 was reduced by 36.5 K and 26.3 K in the presence of tubular and spherical Fe₂O₃, respectively, at 10 K·min⁻¹. The activation energy (E_a) of TKX-50, determined by the iso-conversional method, was significantly reduced in the presence of both tubular and spherical Fe₂O₃. The results indicated that the microstructure of the catalyst has a significant effect on its catalytic performance for TKX-50 thermal decomposition, and that tubular Fe₂O₃ with hollow microstructure possesses better catalytic activity than spherical Fe₂O₃. The excellent catalytic activity of tubular Fe₂O₃ can be attributed to the hollow microstructure, which has more active sites for TKX-50 thermal decomposition.     

The Crystallization and Melting Behaviors of PDLA-b-PBS-b-PDLA Tri-block Copolymers

In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are investigated.Although both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different variations.For the PDLA block,its crystallization behaviors are mainly influenced by temperature and block length.The crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block length.The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°C.Crystallizing at higher temperature,the crystallization rates increase at first and then decrease with block length.The crystallization rates decrease as elevating the crystallization temperature.The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures.For the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block.The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 specimen.The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature.This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.     

Spatially and electrically tunable random lasing based on a polymer-stabilised blue phase liquid crystal-wedged cell

ABSTRACT

We demonstrate a spatially and electrically tunable random lasing based on polymer-stabilized blue phase liquid crystal (PS-BPLC)-wedged cell. The spatially tunable random lasers can be obtained from the laser dye-doped PS-BPLC-wedged cell through changing the pump positions, where the emission wavelength of the random laser can be tuned due to the thickness gradient of the wedged cell, which affects the scattering mean free path. Additionally, applying different electric fields can also tune the laser emission wavelength. The changing of refractive index due to the Kerr effect leads to a change in the scattering mean free path, resulting in shift of lasing wavelength. This PS-BPLC-wedged cell device has a great potential in applications of speckle-free imaging, document coding, biomedicine and other photonic devices.