Enhanced Interfacial Stability of Hybrid‐Electrolyte Lithium‐Sulfur Batteries with a Layer of Multifunctional Polymer with Intrinsic Nanoporosity

The use of lithium‐ion conductive solid electrolytes offers a promising approach to address the polysulfide shuttle and the lithium‐dendrite problems in lithium‐sulfur (Li‐S) batteries. One critical issue with the development of solid‐electrolyte Li‐S batteries is the electrode–electrolyte interfaces. Herein, a strategic approach is presented by employing a thin layer of a polymer with intrinsic nanoporosity (PIN) on a Li⁺‐ion conductive solid electrolyte, which significantly enhances the ionic interfaces between the electrodes and the solid electrolyte. Among the various types of Li⁺‐ion solid electrolytes, NASICON‐type Li_1+xAl_xTi_2‐x(PO₄)₃ (LATP) offers advantages in terms of Li⁺‐ion conductivity, stability in ambient environment, and practical viability. However, LATP is susceptible to reaction with both the Li‐metal anode and polysulfides in Li‐S batteries due to the presence of easily reducible Ti⁴⁺ ions in it. The coating with a thin layer of PIN presented in this study overcomes the above issues. At the negative‐electrode side, the PIN layer prevents the direct contact of Li‐metal with the LATP solid electrolyte, circumventing the reduction of LATP by Li metal. At the positive electrode side, the PIN layer prevents the migration of polysulfides to the surface of LATP, preventing the reduction of LATP by polysulfides.     

块状纳米孔超级绝热材料的制备与表征

以正硅酸乙酯为硅源,采用两步溶胶-凝胶法结合超临界干燥技术制备出了块状无裂纹SiO_2气凝胶,体积密度在50kg·m~(-3)和300kg·m~(-3)之间,样品尺寸约为300mm×300mm×50mm。热学测试表明,常温常压下体积密度大约为100kg·m~(-3)的样品导热系数为0．020 W/m·K,并采用XRD、SAXS、BJH和SEM等其他方法对典型样品(100kh·m~(-3))进行了测试。测试结果表明,SiO_2气凝胶是非晶态的,并且具有纳米多孔结构(骨架颗粒平均粒径为6．8nm,孔径主要集中在10～20nm范围内,而且所有孔径都在70nm以内)。因而可作为具有一定潜在应用价值的块状纳米孔超级绝热材料。     

Aerogels—Nanoporous materials part I: Sol-gel process and drying of gels

Aerogels are highly porous nanostructured materials made in a sol-gel process, generally followed by supercritical drying in an autoclave. Today considerable activities are also devoted to subcritical drying under ambient conditions. Aerogels have been made of inorganic substances such as SiO₂, Al₂O₃, TiO₂ etc. or organic components (resorcinol and melamine formaldehyde) in transparent, translucent and opaque form. Even electrically conductive carbon aerogels are available today. An important step with respect to mass application is the production of granular SiO₂-aerogels with water glass as a precursor. Also of practical importance is the hot-pressing of aerogel sheets from granular or powdered fills.In this paper we shall describe the formation of the organic and inorganic gels and the various procedures to extract the pore fluid without or with little shrinkage. A subsequent paper will be devoted to the characterization and the application of aerogels.     

脱合金法制备纳米多孔金研究进展

纳米多孔金作为一种重要的结构功能材料,在过滤、催化剂载体、传感器、光催化、微流体及分离等方面有着巨大的应用前景。文章综述了纳米多孔金的制备方法。一脱合金法以及最新进展,介绍了脱合金的原理、纳米多孔金的性能以及将来的应用领域     

Mechanism of Low‐Temperature Protonic Conductivity in Bulk,High‐Density,Nanometric Titanium Oxide

Uncovering the mechanism of low‐temperature protonic conduction in highly dense nanostructured metal oxides opens the possibility to exploit the application of simple ceramic electrolytes in proton exchange fuel cells, overcoming the drawbacks related to the use of polymeric membranes. High proton conducting, highly dense (relative density 94 vol%) TiO₂ samples are prepared by a fast pressure‐assisted sintering method, which allows leaving behind an interconnected network of open nanoporosity. Solid‐state ¹H NMR is used to characterize the presence of strongly associated water confined in the nanopores and hydroxyl moieties bonded to the pores walls, providing a model to explain the unusually high protonic conductivity. At the lowest temperatures (T < 55 °C) protons hop between confined water molecules, according to a Grotthuss mechanism. The resulting conductivity values are however much higher than those of liquid water, indicating a significant increase in the charge carriers concentration. At higher temperatures (up to 450 °C) unexpected proton conduction is still present, thanks to the persistence of hydroxyl groups, derived from water chemisorption, which still produce protons by ionization. The phenomenon is strongly dependent on grain size, and not explicable by simple geometric brick‐layer models, suggesting that the enhanced ionization could rely on space charge region effects.     

辽河西部凹陷页岩油气富集主控因素

研究发现,泥页岩的有机质含量、成熟度、有机质类型、孔缝特征及厚度等内部因素是其能否富集的关键条件。以沙河街组沙三下亚段(Es33)和沙四上亚段(Es41)为例,在页岩油气影响因素研究的基础上,运用多因素综合评价、部分因素重点分析的方法,分别揭示Es33及Es41页岩油气富集的主控因素。综合认为,Es33有效厚度大,有机质丰度中等,热演化程度适中,有机质类型多样,气测异常明显、含油气性好,页岩油气共生,主要受有机质丰度影响;同Es33相比,Es41具有较高的有机质丰度,但有机质类型与热演化程度匹配较差,未能达到页岩气富集的条件,主体发育页岩油。因此,明确页岩油气富集的主控因素,是寻找页岩油气赋存有利区域的前提,对辽河坳陷页岩油气的勘探开发具有现实意义。     

Structural Investigation of Resorcinol Formaldehyde and Carbon Aerogels Using SAXS and BET

The structure of organic RF aerogels (RF Recorcinol Formaldehyde) and carbon aerogels, their pyrolized counterparts, can be modified upon variation of the resorcinol to catalyst (RC) ratio. RF aerogels with RC ratios between 100 and 1500 have been produced in steps of 100. The densities for the organic aerogels were kept in the range of 350 to 390 kg m^-3. After pyrolysis, these samples have nearly the same density as their RF precursors, except the ones with very low RC ratios. This is due to the combined shrinkage and mass loss during the heat treatment. All samples were investigated using small angle X-ray scattering (SAXS) and nitrogen sorption (BET) as well as transmission electron microscopy (TEM). Two main effects have been observed. On the one hand, the particle/pore diameter distribution widens with increasing RC ratio, i.e., decreasing catalyst concentration. The average pore diameter increases from 20 nm to about 100 nm. On the other hand the pyrolysis generates a considerable amount of micropores in the particles.     

Nanoporous Copper Metal Catalyst in Click Chemistry: Nanoporosity‐Dependent Activity without Supports and Bases

Nanoporous copper (CuNPore) catalysts with tunable nanoporosity were fabricated from Cu₃₀Mn₇₀ alloy by controlling the de‐alloying temperature under free corrosion conditions. The tunable nanoporosity of CuNPore led to a significant enhancement of catalytic activity in click chemistry without using any supports and bases. Characterization of CuNPore surface, high reusability, leaching experiment, and formation of nanostructured copper acetylide revealed that the click reaction occurred at the catalyst surface.     

3D Bicontinuous Nanoporous Reduced Graphene Oxide for Highly Sensitive Photodetectors

Reduced graphene oxide (RGO) is an important graphene derivative for applications in photonics and optoelectronics because of the band gap created by chemical oxidation. However, most RGO materials made by chemically exfoliated graphite oxide are 2D flakes. Their optoelectronic performance deteriorates significantly as a result of weak light‐matter interaction and poor electrical contact between stacking flakes. Here we report a bicontinuous 3D nanoporous RGO (3D np‐RGO) with high optoelectronic performance for highly sensitive photodetectors. 3D np‐RGO demonstrates a over 40 times higher light absorption than monolayer graphene materials and at least two orders of magnitude higher electron mobility than conventional RGO from discrete RGO flakes. The np‐RGO with an optimal reduction state shows ultrahigh photoresponse of 3.10 3 10⁴ A W^?1 at room temperature, approximately four orders of magnitude higher than graphene and other graphene derivatives at similar levels of light intensity radiations, and the excellent external quantum efficiency of 1.04 3 10⁷% better than commercial silicon photodetector. The ultrahigh capability of conversing photons to photocurrent originates from strongly enhanced light absorption, facilitated photocarrier transport, and tunable oxygenous defects and reduction states in the 3D interconnected bicontinuous RGO network.