Fe3O4@C Nanotubes Grown on Carbon Fabric as a Free-Standing Anode for High-Performance Li-Ion Batteries

Recently, Li-ion batteries (LIBs) have attracted extensive attention owing to their wide applications in portable and flexible electronic devices. Such a huge market for LIBs has caused an ever-increasing demand for excellent mechanical flexibility, outstanding cycling life, and electrodes with superior rate capability. Herein, an anode of self-supported Fe₃O₄@C nanotubes grown on carbon fabric cloth (CFC) is designed rationally and fabricated through an in situ etching and deposition route combined with an annealing process. These carbon-coated nanotube structured Fe₃O₄ arrays with large surface area and enough void space can not only moderate the volume variation during repeated Li⁺ insertion/extraction, but also facilitate Li⁺/electrons transportation and electrolyte penetration. This novel structure endows the Fe₃O₄@C nanotube arrays stable cycle performance (a large reversible capacity of 900 mA h g⁻¹ up to 100 cycles at 0.5 A g⁻¹) and outstanding rate capability (reversible capacities of 1030, 985, 908, and 755 mA h g⁻¹ at 0.15, 0.3, 0.75, and 1.5 A g⁻¹, respectively). Fe₃O₄@C nanotube arrays still achieve a capacity of 665 mA h g⁻¹ after 50 cycles at 0.1 A g⁻¹ in Fe₃O₄@C//LiCoO₂ full cells.     

Generation of NOON States in Waveguide Arrays

A method to generate NOON states with three photons by injecting photons in an array of three waveguides is presented. Conditional measurements project the wave function in a given (desired) state. In passing, it is shown how the array of three waveguides, that effectively reproduces the interaction of three fields, may be reduced to the interaction of two fields.     

In-situ preparation and electrochromic properties of TiO2/PTPA-HTAN core-shell nanocomposite film

A new star-shaped structure conjugated microporous polymers, poly (2,8,14-tri[4-diphenyl-benzene]-hexaazatrinaphthylene) (PTPA-HATN), was designed and in-situ electrochemically polymerized on the surfaces of FTO electrodes with a directional alignment TiO₂ nanorod array to obtain TiO₂/PTPA-HATN core-shell nanocomposite films. Compared with the PTPA-HATN film, the TiO₂/PTPA-HATN composite film exhibits higher optical contrast and faster response time, with contrast of 57% at 783 nm, coloring time of 3.62 s and discoloring time of 2.55 s (43%, 4.63 s and 4.77 s for PTPA-HATN film, respectively). After 400 cycles, the contrast of nanocomposite film decreased by 28%, while the PTPA-HATN film basically lost its electrochromic properties. A simple three-layer EC prototype device based on TiO₂/PTPA-HATN nanocomposite film constructed with hydrogel electrolyte clearly shows color changes at different voltages. On the one hand, the formation of core-shell porous nanostructure of TiO₂/PTPA-HATN composite film provides a larger ion doping/de-doping interface, shortening the average diffusion length of ions. On the other hand, the large indented polymer-nanorods contact interface makes it difficult for the polymer to detach from the electrode, thus significantly improving the cyclic stability of the composite film.     

Self‐Assembled Cage‐Like Protein Structures

Proteins and protein‐based assemblies represent the most structurally and functionally diverse molecules found in nature. Protein cages, viruses and bacterial microcompartments are highly organized structures that are composed primarily of protein building blocks and play important roles in molecular ion storage, nucleic acid packaging and catalysis. The outer and inner surface of protein cages can be modified, either chemically or genetically, and the internal cavity can be used to template, store and arrange molecular cargo within a defined space. Owing to their structural, morphological, chemical and thermal diversity, protein cages have been investigated extensively for applications in nanotechnology, nanomedicine and materials science. Here we provide a concise overview of the most common icosahedral viral and nonviral assemblies, their role in nature, and why they are highly attractive scaffolds for the encapsulation of functional materials.     

Thermally Tunable Hydrogels Displaying Angle‐Independent Structural Colors

We report the preparation of thermally tunable hydrogels displaying angle‐independent structural colors. The porous structures were formed with short‐range order using colloidal amorphous array templates and a small amount of carbon black (CB). The resultant porous hydrogels prepared using colloidal amorphous arrays without CB appeared white, whereas the hydrogels with CB revealed bright structural colors. The brightly colored hydrogels rapidly changed hues in a reversible manner, and the hues varied widely depending on the water temperature. Moreover, the structural colors were angle‐independent under diffusive lighting because of the isotropic nanostructure generated from the colloidal amorphous arrays.     

Determination of phthalate esters from environmental water samples by micro‐solid‐phase extraction using TiO2 nanotube arrays before high‐performance liquid chromatography

We describe a highly sensitive micro‐solid‐phase extraction method for the pre‐concentration of six phthalate esters utilizing a TiO₂ nanotube array coupled to high‐performance liquid chromatography with a variable‐wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2‐ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting‐out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3–200 μg/L. The limits of detection were 0.04–0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples.     

Tight Heffter Arrays Exist for all Possible Values

A tight Heffter array is an matrix with nonzero entries from such that (i) the sum of the elements in each row and each column is 0, and (ii) no element from appears twice. We prove that exist if and only if both m and n are at least 3. If H has the property that all entries are integers of magnitude at most , every row and column sum is 0 over the integers, and H also satisfies ), we call H an integer Heffter array. We show integer Heffter arrays exist if and only if . Finally, an integer Heffter array is shiftable if each row and column contains the same number of positive and negative integers. We show that shiftable integer arrays exists exactly when both are even.     

Fe-Doped CoS2 Nanoarrays: Efficient Electrocatalytic Nitrate Reduction to Ammonia under Ambient Conditions

The electrocatalytic nitrate reduction reaction (NO₃⁻RR) enables the reduction of nitrate to ammonium ions under ambient conditions. It was considered as an alternative reaction for the production of ammonia (NH₃) in recent years. In this paper, we report that the Fe doping CoS₂ nanoarrays can effectively catalyze the formation of NH₃ from nitrate (NO₃⁻) under ambient conditions. This is mainly due to the increase of the NO₃⁻ reaction active site by Fe doping and the porous nanostructure of the catalyst, which greatly improves the catalytic activity. Specifically, at −0.9 V vs. RHE, the NH₃ yield rate (R_NH3) of Fe−CoS₂/CC is 17.8×10⁻² mmol h⁻¹ cm⁻² with Faraday Efficiency (FE) of 88.93 %. Besides, such catalyst shows good durability and catalytic stability, which provides the possibility for the future application of electrocatalytic NH₃ production.     

Needle-like cobalt phosphide arrays grown on carbon fiber cloth as a binder-free electrode with enhanced lithium storage performance

Cobalt phosphide(CoP) is a promising anode candidate for lithium-ion batteries(LIBs) due to its high specific capacity and low working potential.However,the poor cycling stability and rate performance,caused by low electrical conductivity and huge volume variation,impede the further practical application of CoP anode materials.Herein,we report an integrated binder-free electrode featuring needle-like CoP arrays grown on carbon fiber cloth(CC) for efficient lithium storage.The as-prepared CoP/CC electrode integrates the advantages of 1 D needle-like CoP arrays for efficient electrolyte wettability and fast cha rge transpo rtation,and 3 D CC substrate for superior mechanical stability,flexibility and high conductivity.As a result,the CoP/CC electrode delivers an initial specific capacity of 1283 mAh/g and initial Coulombic effeciencies of 85.4%,which are much higher than that of conventional CoP electrode.Notably,the Co P/CC electrode shows outstanding cycling performance up to 400 cycles at 0.5 A/cm² and excellent rate performance with a discharge capacity of 549 mAh/g even at 5 A/cm².This work demonstrates the great potential of integrated CoP/CC hybrid as efficient bind-free and freestanding electrode for LIBs and future flexible electronic devices.     

在光催化还原CO2中具有高催化效率的八面体Cu2O修饰的TiO2纳米管

光催化还原CO2生成烃类燃料是一种可同时解决全球变暖和能源危机问题的最有效途径之一。尽管这方面的研究已经取得了一定的进展,但是整体的光催化转换效率还非常低。因此,需要发展更加高效的催化剂。由于半导体材料禁带宽度与太阳光谱相匹配,人们已经对其进行了广泛研究。其中TiO2因具有无毒、强氧化性以及良好的光学和电学性质等而成为最主要的研究对象。但是对于光催化还原CO2反应来说, TiO2仍存在很多不足,如只能吸收太阳光谱中的紫外光,光生载流子会快速结合,以及光生空穴的强氧化能力等,这些都限制了其光催化还原CO2的效率。采用窄禁带宽度半导体修饰TiO2是解决上述不足的有效途径之一。本文采用简单的电化学方法成功制备了一种由窄禁带半导体Cu2O修饰的TiO2纳米管(TNTs)的复合物,并运用扫描电子显微镜(SEM)、X射线衍射(XRD)以及X射线光电子能谱(XPS)表征了所制备复合物的形貌、化学组成和结晶度。表征结果显示,所制备的TiO2为整齐排列的纳米管阵列结构;复合物中的纳米颗粒为Cu2O;当电化学沉积Cu2O的时间为5 min时,得到的Cu2O纳米颗粒初步呈类八面体结构。随着沉积时间的增加, Cu2O颗粒尺寸增加,具有八面体结构。 XRD和XPS结果表明, TiO2纳米管为锐钛矿,八面体Cu2O纳米颗粒的主要暴露晶面为(111)面。我们还进一步研究了不同量Cu2O纳米颗粒修饰的TiO2纳米管复合物在可见光以及模拟太阳光下光催化还原CO2的能力。在可见光下,由于自身的禁带宽度,纯净的TiO2纳米管没有任何光催化还原CO2的能力;经过Cu2O纳米颗粒的修饰,复合物显现出明显的光催化还原CO2的能力,其中经过30 min Cu2O沉积的TNTs具有最高的光催化效率。在模拟太阳光下,经过15 min Cu2O沉积的TNTs具有最高的光催化效率。在所有光催化还原CO2过程中,主要碳氢产物为甲烷。为了深入地理解该复合体系在还原CO2中的高催化效率,我们对催化剂进行了进一步的表征。紫外-可见漫反射光谱表明, Cu2O八面体纳米颗粒的沉积将TNTs的吸收光谱拓展到了可见光区域,提高了复合物对太阳光的吸收能力。此外,我们还通过测试所制样品的光电流反应、荧光发射光谱以及电化学阻抗谱,研究了催化剂中光生电子和空穴的分离和迁移能力。结果表明,适量的Cu2O沉积提高了复合物对光的吸收能力,增加了光生载流子的数量,从而使更多的光生载流子参与光催化反应。综上,本文首次报道了八面体Cu2O纳米颗粒修饰TNTs复合物的光催化还原CO2的能力。在一定量的Cu2O纳米颗粒修饰下,该复合物在光催化还原CO2生成烃类反应中表现出高效性。经过一系列详细的表征和讨论,我们认为其高效性主要源于三个方面：(1) TNTs的管状结构为反应物的吸附提供了大量的活性位点,同时一维的管状结构更有利于光生载流子的运载,从而提高了电子和空穴的分离;(2) Cu2O纳米颗粒的修饰提高了催化剂对光的吸收,促进催化剂最大程度地利用太阳光;(3) TiO2和Cu2O之间导带以及价带位置的匹配,在减少光生载流子复合的同时也降低了TiO2价带上空穴的氧化能力,从而抑制了CO2还原产物的再氧化过程。