Synthesis, characterization and photophysics of alkyne bridged bimetallic rhenium(I) and ruthenium(II) complexes

Six new homobimetallic and heterobimetallic complexes of rhenium(I) and ruthenium(II) bridged by ethynylene spacer [(CO)₃(bpy)Re(BL)Re(bpy)(CO)₃]²⁺ [Cl(bpy)₂Ru(BL)Ru(bpy)₂Cl]²⁺ and [(CO)₃(bpy)Re(BL)Ru(bpy)₂Cl]²⁺ (bpy = 2,2′-bipyridine, BL = 1,2-bis(4-pyridyl)acetylene (bpa) and 1,4-bis(4-pyridyl)butadiyne (bpb) are synthesized and characterized. The electrochemical and photophysical properties of all the complexes show a weak interaction between two metal centers in heterobimetallic complexes. The excited state lifetime of the complexes is increased upon introduction of ethynylene spacer and the transient spectra show that this is due to delocalization of electron in the bridging ligand. Also, intramolecular energy transfer from *Re(I) to Ru(II) in Re–Ru heterobimetallic complexes occurs with a rate constant 4 × 10⁷ s⁻¹.     

能源微藻采收及油脂提取技术

微藻具有光合效率高、生长周期短、油含量高等特性,是一种极具前景的生物柴油大宗原料。藻体采收和油脂提取是决定微藻柴油生产成本的关键环节,此下游技术的改进对提高微藻产油的经济性意义重大。本文综述了国内外微藻培养液的浓缩采收方法,并对絮凝沉降、絮凝气浮、离心和过滤等方法的作用机制和采收效率进行比较;阐述了目前微藻油脂的提取技术,从操作条件和能量消耗角度分别对有机溶剂、超临界和亚临界法进行评价;特别介绍了一种同时实现微藻生长和油脂提取的新型微藻油脂原位萃取法;最后总结了微藻能源下游技术中存在的主要问题和今后的发展方向,为进一步提高微藻生物柴油经济性提出参考性意见。     

Synergetic ternary metal oxide nanodots-graphene cathode for high performance zinc energy storage

Zinc-based electrochemistry energy storage with high safety and high theoretical capacity is considered to be a competitive candidate to replace lithium-ion batteries. In electrochemical energy storage, multi-metal oxide cathode materials can generally provide a wider electrochemical stability window and a higher capacity compared with single metal oxides cathode. Here, a new type of cathode material, MnFe₂Co₃O₈ nanodots/functional graphene sheets, is designed and used for aqueous hybrid Zn-based energy storage. Coupling with a hybrid electrolyte based on zinc sulfate and potassium hydroxide, the as-fabricated battery was able to work with a wide electrochemical window of 0.1∼1.8 V, showed a high specific capacity of 660 mAh/g, delivered an ultrahigh energy density of 1135 Wh/kg and a scalable power density of 5754 W/kg (calculated based on the cathode), and displayed a long cycling life of 1000 cycles. These are mainly attributed to the valence charge density distribution in MnFe₂Co₃O₈ nanodots, the good structural strengthening as well as high conductivity of the cathode, and the right electrolyte. Such cathode material also exhibited high electrocatalytic activity for oxygen evolution reaction and thus could be used for constructing a Zn-air battery with an ultrahigh reversible capacity of 9556 mAh/g.     

基于Rasch模型的高中化学学科核心素养测评研究——以“变化观念与平衡思想”为例

以《普通高中化学课程标准(2017年版)》对“变化观念与平衡思想”素养的内涵描述和水平划分为例,开发高中生“变化观念与平衡思想”素养测试题,运用Rasch测量模型对工具的质量进行检验、优化并加以运用。结合测试数据调查了学生“变化观念与平衡思想”素养水平现状,分析了研究被试能力值的学校差异和班级差异,并对该素养培养提出建议。     

Hydrogen energy currency: Beyond state-of-the-art transition metal oxides for oxygen electrocatalysis

In this opinion piece, we highlight and discuss beyond state-of-the-art transition metal oxide materials for the oxygen evolution reaction and oxygen reduction reaction, which are essential for the renewable energy conversion and storage of H₂ to electricity. We pinpoint some of the synthetic routes taken and discuss essential measurements required in the highlighted works, which others should undertake to achieve highly active and stable oxygen evolution reaction and oxygen reduction reaction catalysts in both acidic and alkaline media.     

Probing electrochemical surface/interfacial reactions with liquid cell transmission electron microscopy: a challenge or an opportunity?

Understanding electrochemical reactions at material surfaces and interfaces is crucial for the development of next-generation battery electrodes and electrocatalysts — two key areas in global CO₂ mitigation strategies. By allowing these dynamic reactions to be captured on an atomic level and in real-time, the liquid cell transmission electron microscopy (LC-TEM) technique has carved itself a niche in energy materials research. Several key problems are being investigated, ranging from addressing dendrite growth in lithium-ion batteries that cause a thermal runaway, to understanding mass loss of expensive platinum catalysts in native hydrogen fuel-cell environments. Unfortunately, as with any emerging technology, LC-TEM is not without its share of problems. Undesired electron beam interactions with the liquid, low containable liquid volumes, and poor spatial resolution due to plural scattering are only some of the many problems which must still be fully resolved.This short review highlights the strengths and weaknesses behind LC-TEM while providing updates on the latest applications and technical advances in the areas of dose-minimization strategies, improvements in analytical abilities, and novel closed-cell design. Notable future opportunities include off-axis holography, diffraction tomography, and pump-probe laser excitations — all carried out in liquids.     

NIR-plasmon-enhanced Systems for Energy Conversion and Environmental Remediation

The introduction of plasmons is an important method to solve the insufficient utilization of the full spectrum of solar energy by semiconductor catalysts. However, semiconductor catalysts combined with traditional noble metal plasmons(Au, Ag) can only extend the absorption spectrum to partially visible light. In order to further improve the photoenergy absorption efficiency of catalysts, they need to be able to effectively utilize near-infrared light, which has become a new research direction. Recent studies have shown that traditional noble metal plasmons can absorb a part of NIR through special morphology, size control and material composite. At the same time, gratifying achievements have been made in the application of plasmonic semiconductors with broad spectrum absorption in catalysis. This article reviews the principles of generating and regulating plasmonic effects in different catalytic systems. The applications of plasmon absorption of near-infrared light in energy conversion and environmental remediation have also been presented.     

A comprehensive study on the impact of RGO/MWCNT hybrid filler reinforced polychloroprene rubber multifunctional nanocomposites

Flexible dielectric chloroprene rubber (CR) nanocomposites reinforced by one-dimensional carbon nanotube (CNT)/two dimensional reduced graphene oxide hybrids have been prepared using two-roll mill mixing technique. Non-covalent π-π interaction between multiwalled carbon nanotubes (MWCNTs) and reduced graphene oxide (RGO) nanosheets and the secondary interaction between fillers and chloroprene rubber matrix are responsible for generating the effective load transfer between RGO/MWCNTs and CR. The prepared RGO-MWCNT hybrid nanocomposites with high dielectric constant (≈650), low dielectric loss (≈0.42) and high energy storage efficiency (78.6%) values are practically good enough to use as a low cost polymeric dielectric layer in transistors. Furthermore, the prepared nanocomposites showed excellent electromagnetic effectiveness; a maximum shielding efficiency of 11.87 dB @ 3.5 GHz was achieved at 4 phr of MWCNT loading. This excellent electromechanical performance can be ascribed to the synergistic effect of RGO-MWCNT hybrid suggesting that this novel hybrid nanocomposite serves as an attractive candidate in modern electronics and electric power systems.     

Molecular design of a new family of bridged bis(multinitro-triazole) with outstanding oxygen balance as high-density energy compounds

A new family of bridged bis(multinitro-triazole) was designed and investigated using the density functional theory method. The density, oxygen balance, heat of formation, detonation performance, and impact sensitivity were calculated systematically. The results show that the multinitromethyl groups play an important role in increasing densities. At the same time, different bridged groups present diverse performances with high density (1.86-1.96 g·cm⁻³), excellent detonation properties (V = 8.72 km·s⁻¹-9.20 km·s⁻¹; P = 34.54 GPa-39.49 GPa), outstanding oxygen balance (0%-11.59%), and acceptably impact sensitivity. Especially, tetrazine (M7)-bridged and diaminofurazan (M9)-bridged groups are very helpful for enhancing their detonation performance (V_(M7) = 9.12 km·s⁻¹, P_(M7) = 38.51 GPa; V_(M9) = 9.20 km·s⁻¹, P_(M9) = 39.49 GPa), respectively, which are better than RDX. They could be seen as the potential candidates of high energy density materials (HEDMs).     

电化学储能及传感器用氮化碳基复合材料设计策略

理性设计的氮化碳(C_3N_4)基纳米复合材料具有优异的电子结构和光电化学性能。这使其不仅局限于光催化领域,更已经成为电化学催化领域的新宠。通过调控纳米结构,可以协同发挥复合材料性能激发电化学性能。以电化学储能及传感应用为目标,材料结构为切入点,深入分析并综述了石墨相氮化碳及其复合材料的材料设计方法、结构和性能,为进一步深化g-C_3N_4的科学化应用提供思路。