Record‐High Superconductivity in Niobium–Titanium Alloy

The extraordinary superconductivity has been observed in a pressurized commercial niobium–titanium alloy. Its zero‐resistance superconductivity persists from ambient pressure to the pressure as high as 261.7 GPa, a record‐high pressure up to which a known superconducting state can continuously survive. Remarkably, at such an ultra‐high pressure, although the ambient pressure volume is shrunk by 45% without structural phase transition, the superconducting transition temperature (T_C) increases to ≈19.1 K from ≈9.6 K, and the critical magnetic field (H_C2) at 1.8 K has been enhanced to 19 T from 15.4 T. These results set new records for both the T_C and the H_C2 among all the known alloy superconductors composed of only transition metal elements. The remarkable high‐pressure superconducting properties observed in the niobium–titanium alloy not only expand the knowledge on this important commercial superconductor but also are helpful for a better understanding on the superconducting mechanism.     

SMAT纳米钛的组织及力学性能研究

对纯钛进行表面机械研磨处理(SMAT),并研究其组织结构以及力学性能的变化.研究结果表明,径SMAT处理后,纯钛的表面形成了纳米晶层,而整体转变成为梯度材料.与SMAT处理前的纯钛相比,处理后材料的弹性模量下降,屈服强度和抗拉强度提高而塑性下降.     

梭形纳米二氧化钛溶胶的制备及其抗菌性能和细胞毒性

采用水热合成法制备了纳米二氧化钛溶胶,通过XRD、TEM和FT-Raman对所得溶胶中纳米粒子的晶形、大小及形貌进行了表征,并探讨了该溶胶对大肠杆菌和金黄色葡萄球菌的抗抑性能以及对原代培养的小鼠腹腔巨噬细胞的毒性效应。结果表明,所得溶胶中纳米二氧化钛粒子均为梭形锐钛型纳米二氧化钛,宽平均为20nm,长平均为100nm。溶胶对大肠杆菌和金黄色葡萄球菌的抑菌率在作用4h后均达到90%以上,抑菌率达到90%以上的溶胶质量浓度为1000mg/L。溶胶加入细胞培养液中后能明显影响巨噬细胞的生长形态,24h后巨噬细胞都呈现出不同程度的回缩变形,细胞间隙增大,巨噬细胞内颗粒物随纳米TiO2颗粒浓度的升高而增多,细胞折光性下降;在24h内对巨噬细胞的生长具有一定的增殖作用,在48h内都呈现一定的抑制作用,且存在剂量-效应关系,随着纳米TiO2浓度的升高,其对巨噬细胞的生长抑制越显著。     

Hybrid Crystals Comprising Metal–Organic Frameworks and Functional Particles: Synthesis and Applications

Hybrid crystals containing encapsulated functional species exhibit promising novel physical and chemical properties. The realization of many properties critically depends on the selection of suitable functional species for incorporation, the rational control of the crystallinity of the host materials, and the manipulation of the distribution of the encapsulated species; only a few hybrid crystals achieve this. Here, a novel synthetic method enables the encapsulation of functional species within crystalline metal–organic frameworks (MOFs). Various kinds of single‐crystalline MOFs with incorporated particles are presented. The encapsulated particles can be distributed in a controllable manner, and the hybrid crystals are applied to the heterogeneous catalysis of the reduction of nitroarenes. These findings suggest a general approach for the construction of MOF materials with potential applications; by combining species and MOFs with suitable functionalities, new properties—not possible by other means—may arise.     

Nanoconfined Nickel@Carbon Core–Shell Cocatalyst Promoting Highly Efficient Visible‐Light Photocatalytic H2 Production

The realization of large‐scale solar hydrogen (H₂) production relies on the development of high‐performance and low‐cost photocatalysts driven by sunlight. Recently, cocatalysts have demonstrated immense potential in enhancing the activity and stability of photocatalysts. Hence, the rational design of highly active and inexpensive cocatalysts is of great significance. Here, a facile method is reported to synthesize Ni@C core–shell nanoparticles as a highly active cocatalyst. After merging Ni@C cocatalyst with CdS nanorod (NR), a tremendously enhanced visible‐light photocatalytic H₂‐production performance of 76.1 mmol g^?1 h^?1 is achieved, accompanied with an outstanding quantum efficiency of 31.2% at 420 nm. The state‐of‐art characterizations (e.g., synchrotron‐based X‐ray absorption near edge structure) and theoretical calculations strongly support the presence of pronounced nanoconfinement effect in Ni@C core–shell nanoparticles, which leads to controlled Ni core size, intimate interfacial contact and rapid charge transfer, optimized electronic structure, and protection against chemical corrosion. Hence, the combination of nanoconfined Ni@C with CdS nanorod leads to significantly improved photocatalytic activity and stability. This work not only for the first time demonstrates the great potential of using highly active and inexpensive Ni@C core–shell structure to replace expensive Pt in photocatalysis but also opens new avenues for synthesizing cocatalyst/photocatalyst hybridized systems with excellent performance by introducing nanoconfinement effect.     

Charge-Density-Wave Pseudogap and Two-Dimensional Superconductivity Within Strong-Coupling Description

We have considered the role of charge-density-pseudogap for phonon-mediated super-conductivity on two-dimensional lattice. The propagators that enter generalized Eliashberg equations have been renormalized to account for quasi-particle energies related to the formation of the pseudogap, which has been assumed to be of d-wave symmetry. We have evaluated the superconducting transition temperature T_c as a function of doping. It occurs that T_c for d-wave symmetry well reflects experimental behavior. Our results for the isotope shift exponent show that at low doping, the presence of the pseudogap may contribute to > 1/2 as well as to > 1/2 values.     

Structural Color Palettes of Core–Shell Photonic Ink Capsules Containing Cholesteric Liquid Crystals

Photonic microcapsules with onion‐like topology are microfluidically designed to have cholesteric liquid crystals with opposite handedness in their core and shell. The microcapsules exhibit structural colors caused by dual photonic bandgaps, resulting in a rich variety of color on the optical palette. Moreover, the microcapsules can switch the colors from either core or shell depending on the selection of light‐handedness.     

Sustainable Synthesis of Co@NC Core Shell Nanostructures from Metal Organic Frameworks via Mechanochemical Coordination Self‐Assembly: An Efficient Electrocatalyst for Oxygen Reduction Reaction

Herein, a new type of cobalt encapsulated nitrogen‐doped carbon (Co@NC) nanostructure employing Zn_xCo_1?x(C₃H₄N₂) metal–organic framework (MOF) as precursor is developed, by a simple, ecofriendly, solvent‐free approach that utilizes a mechanochemical coordination self‐assembly strategy. Possible evolution of Zn_xCo_1?x(C₃H₄N₂) MOF structures and their conversion to Co@NC nanostructures is established from an X‐ray diffraction technique and transmission electron microscopy analysis, which reveal that MOF‐derived Co@NC core–shell nanostructures are well ordered and highly crystalline in nature. Co@NC–MOF core–shell nanostructures show excellent catalytic activity for the oxygen reduction reaction (ORR), with onset potential of 0.97 V and half‐wave potential of 0.88 V versus relative hydrogen electrode in alkaline electrolyte, and excellent durability with zero degradation after 5000 potential cycles; whereas under similar experimental conditions, the commonly utilized Pt/C electrocatalyst degrades. The Co@NC–MOF electrocatalyst also shows excellent tolerance to methanol, unlike the Pt/C electrocatalyst. X‐ray photoelectron spectroscopy (XPS) analysis shows the presence of ORR active pyridinic‐N and graphitic‐N species, along with CoN_x? C_y and Co? N_x ORR active (M–N–C) sites. Enhanced electron transfer kinetics from nitrogen‐doped carbon shell to core Co nanoparticles, the existence of M–N–C active sites, and protective NC shells are responsible for high ORR activity and durability of the Co@NC–MOF electrocatalyst.     

Advancements in Copper Nanowires: Synthesis,Purification, Assemblies,Surface Modification,and Applications

Copper nanowires (CuNWs) are attracting a myriad of attention due to their preponderant electric conductivity, optoelectronic and mechanical properties, high electrocatalytic efficiency, and large abundance. Recently, great endeavors are undertaken to develop controllable and facile approaches to synthesize CuNWs with high dispersibility, oxidation resistance, and zero defects for future large‐scale nano‐enabled materials. Herein, this work provides a comprehensive review of current remarkable advancements in CuNWs. The Review starts with a thorough overview of recently developed synthetic strategies and growth mechanisms to achieve single‐crystalline CuNWs and fivefold twinned CuNWs by the reduction of Cu(I) and Cu(II) ions, respectively. Following is a discussion of CuNW purification and multidimensional assemblies comprising films, aerogels, and arrays. Next, several effective approaches to protect CuNWs from oxidation are highlighted. The emerging applications of CuNWs in diverse fields are then focused on, with particular emphasis on optoelectronics, energy storage/conversion, catalysis, wearable electronics, and thermal management, followed by a brief comment on the current challenges and future research directions. The central theme of the Review is to provide an intimate correlation among the synthesis, structure, properties, and applications of CuNWs.     

Competition between Auger Recombination and Hot‐Carrier Trapping in PL Intensity Fluctuations of Type II Nanocrystals

Performing time‐tagged, time‐correlated, single‐photon‐counting studies on individual colloidal nanocrystal quantum dots (NQDs), the evolution of photoluminescence (PL) intensity‐fluctuation behaviors in near‐infrared (NIR) emitting type II, InP/CdS core‐shell NQDs is investigated as a function of shell thickness. It is observed that Auger recombination and hot‐carrier trapping compete in defining the PL intensity‐fluctuation behavior for NQDs with thin shells, whereas the role of hot‐carrier trapping dominates for NQDs with thick shells. These studies further reveal the distinct ramifications of altering either the excitation fluence or repetition rate. Specifically, an increase in laser pump fluence results in the creation of additional hot‐carrier traps. Alternately, higher repetition rates cause a saturation in hot‐carrier traps, thus activating Auger‐related PL fluctuations. Furthermore, it is shown that Auger recombination of negatively charged excitons is suppressed more strongly than that of positively charged excitons because of the asymmetry in the electron‐hole confinement in type II NQDs. Thus, this study provides new understanding of how both NQD structure (shell thickness and carrier‐separation characteristics) and excitation conditions can be used to tune the PL stability, with important implications for room‐temperature single‐photon generation. Specifically, the first non‐blinking NQD capable of single‐photon emission in the near‐infrared spectral regime is described.     

Epitaxial Growth of Lattice‐Mismatched Core–Shell TiO2@MoS2 for Enhanced Lithium‐Ion Storage

Core–shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core–shells with two distinct crystal structures. Herein, a controlled synthesis of lattice‐mismatched core–shell TiO₂@MoS₂ nano‐onion heterostructures is successfully developed, using unilamellar Ti_0.87O₂ nanosheets as the starting material and the subsequent epitaxial growth of MoS₂ on TiO₂. The formation of these core–shell nano‐onions is attributed to an amorphous layer‐induced heterogrowth mechanism. The number of MoS₂ layers can be well tuned from few to over ten layers, enabling layer‐dependent synergistic effects. The core–shell TiO₂@MoS₂ nano‐onion heterostructures exhibit significantly enhanced energy storage performance as lithium‐ion battery anodes. The approach has also been extended to other lattice‐mismatched systems such as TiO₂@MoSe₂, thus suggesting a new strategy for the growth of well‐designed lattice‐mismatched core–shell structures.     

Design and Synthesis of Spherical Multicomponent Aggregates Composed of Core–Shell,Yolk–Shell,and Hollow Nanospheres and Their Lithium‐Ion Storage Performances

Micrometer‐sized spherical aggregates of Sn and Co components containing core–shell, yolk–shell, hollow nanospheres are synthesized by applying nanoscale Kirkendall diffusion in the large‐scale spray drying process. The Sn₂Co₃–Co₃SnC_0.7–C composite microspheres uniformly dispersed with Sn₂Co₃–Co₃SnC_0.7 mixed nanocrystals are formed by the first‐step reduction of spray‐dried precursor powders at 900 °C. The second‐step oxidation process transforms the Sn₂Co₃–Co₃SnC_0.7–C composite into the porous microsphere composed of Sn–Sn₂Co₃@CoSnO₃–Co₃O₄ core–shell, Sn–Sn₂Co₃@CoSnO₃–Co₃O₄ yolk–shell, and CoSnO₃–Co₃O₄ hollow nanospheres at 300, 400, and 500 °C, respectively. The discharge capacity of the microspheres with Sn–Sn₂Co₃@CoSnO₃–Co₃O₄ core–shell, Sn‐Sn₂Co₃@CoSnO₃–Co₃O₄ yolk–shell, and CoSnO₃–Co₃O₄ hollow nanospheres for the 200^th cycle at a current density of 1 A g^?1 is 1265, 987, and 569 mA h g^?1, respectively. The ultrafine primary nanoparticles with a core–shell structure improve the structural stability of the porous‐structured microspheres during repeated lithium insertion and desertion processes. The porous Sn–Sn₂Co₃@CoSnO₃–Co₃O₄ microspheres with core–shell primary nanoparticles show excellent cycling and rate performances as anode materials for lithium‐ion batteries.     

808‐nm‐Light‐Excited Lanthanide‐Doped Nanoparticles: Rational Design,Luminescence Control and Theranostic Applications

808 nm‐light‐excited lanthanide (Ln³⁺)‐doped nanoparticles (LnNPs) hold great promise for a wide range of applications, including bioimaging diagnosis and anticancer therapy. This is due to their unique properties, including their minimized overheating effect, improved penetration depth, relatively high quantum yields, and other common features of LnNPs. In this review, the progress of 808 nm‐excited LnNPs is reported, including their i) luminescence mechanism, ii) luminescence enhancement, iii) color tuning, iv) diagnostic and v) therapeutic applications. Finally, the future outlook and challenges of 808 nm‐excited LnNPs are presented.     

Co@Co3O4 Core–Shell Three‐Dimensional Nano‐Network for High‐Performance Electrochemical Energy Storage

An alternative routine is presented by constructing a novel architecture, conductive metal/transition oxide (Co@Co₃O₄) core–shell three‐dimensional nano‐network (3DN) by surface oxidating Co 3DN in situ, for high‐performance electrochemical capacitors. It is found that the Co@Co₃O₄ core–shell 3DN consists of petal‐like nanosheets with thickness of <10 nm interconnected forming a 3D porous nanostructure, which preserves the original morphology of Co 3DN well. X‐ray photoelectron spectroscopy by polishing the specimen layer by layer reveals that the Co@Co₃O₄ nano‐network is core–shell‐like structure. In the application of electrochemical capacitors, the electrodes exhibit a high specific capacitance of 1049 F g^?1 at scan rate of 2 mV/s with capacitance retention of ～52.05% (546 F g^?1 at scan rate of 100 mV) and relative high areal mass density of 850 F g^?1 at areal mass of 3.52 mg/cm². It is believed that the good electrochemical behaviors mainly originate from its extremely high specific surface area and underneath core‐Co “conductive network”. The high specific surface area enables more electroactive sites for efficient Faradaic redox reactions and thus enhances ion and electron diffusion. The underneath core‐Co “conductive network” enables an ultrafast electron transport.     

Symmetry‐Reduction Enhanced Polarization‐Sensitive Photodetection in Core–Shell SbI3/Sb2O3 van der Waals Heterostructure

Structural symmetry is a simple way to quantify the anisotropic properties of materials toward unique device applications including anisotropic transportation and polarization‐sensitive photodetection. The enhancement of anisotropy can be achieved by artificial symmetry‐reduction design. A core–shell SbI₃/Sb₂O₃ nanowire, a heterostructure bonded by van der Waals forces, is introduced as an example of enhancing the performance of polarization‐sensitive photodetectors via symmetry reduction. The structural, vibrational, and optical anisotropies of such core–shell nanostructures are systematically investigated. It is found that the anisotropic absorbance of a core–shell nanowire is obviously higher than that of two single compounds from both theoretical and experimental investigations. Anisotropic photocurrents of the polarization‐sensitive photodetectors based on these core–shell SbI₃/Sb₂O₃ van der Waals nanowires are measured ranging from ultraviolet (UV) to visible light (360–532 nm). Compared with other van der Waals 1D materials, low anisotropy ratio (I_max/I_min) is measured based on SbI₃ but a device based on this core–shell nanowire possesses a relatively high anisotropy ratio of ≈3.14 under 450 nm polarized light. This work shows that the low‐symmetrical core–shell van der Waals heterostructure has large potential to be applied in wide range polarization‐sensitive photodetectors.