Two-Dimensional Germanium Sulfide Nanosheets as an Ultra-Stable and High Capacity Anode for Lithium Ion Batteries

Lithium ion batteries (LIBs) at present still suffer from low rate capability and poor cycle life during fast ion insertion/extraction processes. Searching for high-capacity and stable anode materials is still an ongoing challenge. Herein, a facile strategy for the synthesis of ultrathin GeS₂ nanosheets with the thickness of 1.1 nm is reported. When used as anodes for LIBs, the two-dimensional (2D) structure can effectively increase the electrode/electrolyte interface area, facilitate the ion transport, and buffer the volume expansion. Benefiting from these merits, the as-synthesized GeS₂ nanosheets deliver high specific capacity (1335 mAh g⁻¹ at 0.15 A g⁻¹), extraordinary rate performance (337 mAh g⁻¹ at 15 A g⁻¹) and stable cycling performance (974 mAh g⁻¹ after 200 cycles at 0.5 A g⁻¹). Importantly, our fabricated Li-ion full cells manifest an impressive specific capacity of 577 mAh g⁻¹ after 50 cycles at 0.1 A g⁻¹ and a high energy density of 361 Wh kg⁻¹ at a power density of 346 W kg⁻¹. Furthermore, the electrochemical reaction mechanism is investigated by the means of ex-situ high-resolution transmission electron microscopy. These results suggest that GeS₂ can use to be an alternative anode material and encourage more efforts to develop other high-performance LIBs anodes.     

Nanobody-Ferritin Conjugate for Targeted Photodynamic Therapy

Ferritin is an iron-storage protein nanocage that is assembled from 24 subunits. The hollow cavity of ferritin enables its encapsulation of various therapeutic agents; therefore, ferritin has been intensively investigated for drug delivery. The use of antibody-ferritin conjugates provides an effective approach for targeted drug delivery. However, the complicated preparation and limited protein stability hamper wide applications of this system. Herein, we designed a novel nanobody-ferritin platform (Nb-Ftn) for targeted drug delivery. The site-specific conjugation between nanobody and ferritin is achieved by transglutaminase-catalyzed protein ligation. This ligation strategy allows the Nb conjugation after drug loading in ferritin, which avoids deactivation of the nanobody under the harsh pH environment required for drug encapsulation. To verify the tumor targeting of this Nb-Ftn platform, a photodynamic reagent, manganese phthalocyanine (MnPc), was loaded into the ferritin cavity, and an anti-EGFR nanobody was conjugated to the surface of the ferritin. The ferritin nanocage can encapsulate about 82 MnPc molecules. This MnPc@Nb-Ftn conjugate can be efficiently internalized by EGFR positive A431 cancer cells, but not by EGFR negative MCF-7 cells. Upon 730 nm laser irradiation, MnPc@Nb-Ftn selectively killed EGFR positive A431 cells by generating reactive oxygen species (ROS), whereas no obvious damage was observed on MCF-7 cells. Given that ferritin can be used for encapsulation of various therapeutic agents, this work provides a strategy for facile construction of nanobody-ferritin for targeted drug delivery.     

Iridium-Catalyzed Regioselective B(3)-Alkenylation/B(3,6)-Dialkenylation of o-Carboranes by Direct B−H Activation

Iridium-catalyzed formal alkyne hydroboration with cage B−H of o-carborane has been achieved, leading to the controlled synthesis of a series of 3,6-[trans-(AlkCH=CH)]₂-o-carboranes (Alk=alkyl), 3-cis-(ArCH=CH)-o-carboranes (Ar=aryl), and 3-cis-(ArCH=CH)-6-trans-(AlkCH=CH)-o-carboranes in high yields with excellent regio- and very good cis–trans selectivity. The most electron-deficient B(3,6)−H vertices favor oxidative addition on electron-rich metal centers, which is responsible for the regioselectivity. On the other hand, the configuration of the resultant olefinic units is dominated by alkyne substituents. Alkyl groups lead to a trans-configuration whereas bulky aryl substitutions result in cis-configuration.     

An Efficient and Stable MoS2/Zn0.5Cd0.5S Nanocatalyst for Photocatalytic Hydrogen Evolution

Photocatalytic hydrogen evolution by water splitting is highly important for the application of hydrogen energy and the replacement of fossil fuel by solar energy, which needs the development of efficient catalysts with long-term catalytic stability under light irradiation in aqueous solution. Herein, Zn_0.5Cd_0.5S solid solution was synthesized by a metal–organic framework-templated strategy and then loaded with MoS₂ by a hydrothermal method to fabricate a MoS₂/Zn_0.5Cd_0.5S heterojunction for photocatalytic hydrogen evolution. The composition of MoS₂/Zn_0.5Cd_0.5S was fine-tuned to obtain the optimized 5 wt % MoS₂/Zn_0.5Cd_0.5S heterojunction, which showed a superior hydrogen evolution rate of 23.80 mmol h⁻¹ g⁻¹ and steady photocatalytic stability over 25 h. The photocatalytic performance is due to the appropriate composition and the formation of an intimate interface between MoS₂ and Zn_0.5Cd_0.5S, which endows the photocatalyst with high light-harvesting ability and effective separation of photogenerated carriers.     

Controlled Self-Assembly of Metallacycle-Bridged Gold Nanoparticles for Surface-Enhanced Raman Scattering

In this work, well-defined two-dimensional metallacycles have been successfully employed for the well-controlled self-assembly of gold nanoparticles (AuNPs) into discrete clusters such as dimers, trimers, tetramers, pentamers and even hexamers at the water–oil interface for the first time. Furthermore, the modular construction of metallacycle molecules allows precise control of spacing between the gold nanoparticles. Interestingly, it was found that interparticle spacing below 5 nm created by molecular metallacycles in the resultant discrete gold nanoparticle clusters led to a strong plasmon coupling, thus inducing great field enhancement inside the gap between the NPs. More importantly, different discrete clusters with precise interparticle spacing provide a well-defined system for studying the hot-spot phenomenon in surface-enhanced Raman scattering (SERS); this revealed that the SERS effects were closely related to the interparticle spacing.     

B(C6F5)3/Chiral Phosphoric Acid Catalyzed Ketimine–Ene Reaction of 2-Aryl-3H-indol-3-ones and α-Methylstyrenes

The enantioselective ketimine–ene reaction is one of the most challenging stereocontrolled reaction types in organic synthesis. In this work, catalytic enantioselective ketimine–ene reactions of 2-aryl-3H-indol-3-ones with α-methylstyrenes were achieved by utilizing a B(C₆F₅)₃/chiral phosphoric acid (CPA) catalyst. These ketimine–ene reactions proceed well with low catalyst loading (B(C₆F₅)₃/CPA=2 mol %/2 mol %) under mild conditions, providing rapid and facile access to a series of functionalized 2-allyl-indolin-3-ones with very good reactivity (up to 99 % yield) and excellent enantioselectivity (up to 99 % ee). Theoretical calculations reveal that enhancement of the acidity of the chiral phosphoric acid by B(C₆F₅)₃ significantly reduces the activation free energy barrier. Furthermore, collective favorable hydrogen-bonding interactions, especially the enhanced N−H⋅⋅⋅O hydrogen-bonding interaction, differentiates the free energy of the transition states of CPA and B(C₆F₅)₃/CPA, thereby inducing the improvement of stereoselectivity.     

温度对低共熔溶剂影响的二维拉曼光谱研究

低共熔溶剂（DES）作为一种新式的绿色溶剂，在多种化学过程中表现出色，因此在诸多热门范畴都展现出良好的发展潜力。对DES的光谱分析通常局限在一维光谱技术上，但其分辨率低、谱峰重叠严重等缺点，导致光谱数据存在误差。运用二维拉曼光谱（2D Raman），能够明显提高光谱分辨率，并发现重叠峰位置，获得在外扰条件下不同谱峰的变化顺序及其相互作用等重要信息，以实现对复杂体系的精确分析。以氯化胆碱（ChCl）和ZnCl₂合成的DES为例，利用显微共焦激光拉曼光谱仪分别对ChCl和DES进行拉曼实验，发现与ChCl相比，DES中各处峰的整体强度显著下降，原有的谱峰未消失，说明Zn2+的加入没有破坏ChCl的骨架结构。287 cm-1处出现一个新的特征峰，推测有Zn-Cl配位键的伸缩振动。对DES进行升温拉曼实验，发现随着温度的升高，NC₄的不对称伸缩振动峰强度逐渐减小，峰宽变大，峰形变缓，Zn-Cl配位键伸缩振动峰强度逐渐降低，峰位置基本不变，峰形有明显重叠。运用2D Raman技术对溶液内NC₄和Zn-Cl特征峰的变化进行研究，结果表明，随着温度的升高，溶液中发生ChCl向Ch+的解离过程，Zn2+与Cl-形成了多种配合物，ZnCl-₃，Zn₂Cl-₅，Zn₃Cl-₇之间存在相互转化。不同位置的特征峰随温度的变化顺序不同，将特征峰与团簇进行一一归属，得出了各个团簇对温度的敏感程度。基于量子化学中的密度泛函理论，对推测的物质结构进行构型优化和参数计算，证实了其存在的可能性，同时也验证了2D Raman的分析结果准确可行。这些结果将为DES的后续研究提供理论参考，拓展了二维光谱技术的应用范围。     

Understanding the solubility and crystallization of molybdenum in high-sodium borosilicate glasses: effect of lanthanum oxide

Journal of Radioanalytical and Nuclear Chemistry - The simplified 8-oxide system (SiO2-B2O3-Na2O-Al2O3-CaO-TiO2-MoO3-La2O3) has been prepared under two types of cooling methods, and analyzed with...