Latest ArticlesNiduenes A−F (1−6), six novel sesterterpenoids with unprecedented 5/5/5/5/6 pentacyclic ring skeleton were isolated from endophytic fungus Aspergillus nidulans. Compounds 1 and 2 represent the first examples of aromatic pentacyclic sesterterpenoids. Their structures and configurations were elucidated by spectroscopic data and single-crystal X-ray diffraction analyses. Compound 4 demonstrated potent resensitization of SW620/AD300 cells to paclitaxel (PTX). Rhodamine 123 accumulation assay and docking analysis further support that 4 inhibitory the efflux function of P-glycoprotein (P-gp).
High-efficiency hydrogen production through photoelectrochemical (PEC) water splitting has emerged as a promising solution to address current global energy challenges. Ⅲ-nitride semiconductor photoelectrodes with nanostructures have demonstrated great potential in the near future due to their high light absorption, tunable direct band gap, and strong physicochemical stability. However, several issues, including surface trapping centers, surface Fermi level pinning, and surface band bending, need to be addressed. In this work, enhanced photovoltaic properties have been achieved using gallium nitride (GaN) nanowires (NWs) photoelectrodes by adopting an alkaline solution surface treatment method to reduce the surface states. It was found that surface oxides on NWs can be removed by an alkaline solution treatment without changing the surface morphology through X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and other characterization methods. These findings provide new insights to the development of high-efficiency photoelectrodes for new energy source applications.
Controlling the shape and composition of Pt-based nanocrystals is essential to improve electrocatalytic performance. In this work, we have carefully investigated the evolution process of morphology and composition for Pt and Pt3M (M = Ni, Co) nanocrystals by hydrochloric acid (HCl) etching. As a result, only Pt3Ni nanocrystals successfully formed unsaturated step-like atoms on the surface and then constructed high-index facets (HIFs), while Pt and Pt3Co preserved a good octahedron shape. Density functional theory (DFT) calculation suggests that Cl− ions can be tightly adsorbed on the surface of Pt3Ni rather than other nanocrystals, which hinders the deposition of newly-reduced atoms and thus regulating the surface morphology. Besides, the etching of surface transitional metals further accelerates the formation of HIFs. Boosted by the active sites on the surface, HCl-Pt-Ni exhibited a ~10.8 and ~11.3 times higher oxygen reduction reaction (ORR) mass and specific activities than commercial Pt/C catalyst, and possessed a good durability after 10,000 cycles test. This work gives a deep insight into the design of high-performance Pt-based ORR catalysts.
The composite polymer electrolyte has been obtained via incorporating LiCUST-701 (a new metal–organic rotaxane framework modified by Li+) into poly(ethylene oxide) (PEO) matrix and give a high ionic conductivity of 4.02 × 10−4 S/cm at 60 ℃. DFT calculations were used to visualize the possible diffusion pathway of Li+. The all-solid-state cell assembled with LiFePO4, composite polymer electrolyte and lithium metal foil delivered with excellent cycling capability and stability even under high current densities.
Dynamic covalent imine reactions between 2′,3′-dimethoxy-[1,1′:4′, 1″-terphenyl]-3,3″,5,5″-tetracarbaldehyde (DMTT) and cyclohexanediamine, p-phenylenediamine, and benzidine, respectively, generate a porous organic cage (DMPOC) and two covalent organic frameworks (COFs), USTB-29, and USTB-30. DMPOC shows a [3 + 6] topological cage-like structure according to single crystal X-ray diffraction result. In contrast, both microcrystalline USTB-29 and USTB-30 exhibit two-dimensional monoporous structures in an eclipsed AA stacking style based on powder X-ray diffraction and theoretical simulations. In addition, DMPOC is capable of efficiently absorbing the iodine vapor with an outstanding uptake of 5.10 g/g, much higher than that of USTB-29 (3.07 g/g) and USTB-30 (3.16 g/g). Cage to COFs transformations have been realized from DMPOC to USTB-29 and USTB-30 via the imine bond exchange with slightly increased iodine vapor uptake. Mechanism investigations uncover that both nitrogen and oxygen atoms of POC and COFs contribute to iodine vapor capture due to the formation of charge transfer matter, and loose interaction introducing adaptive expanding voids of DMPOC is suggested to capture more iodine vapor than that of COFs with strong π-π interactions.
Vanadium pentoxide (V2O5) with a layered structure is of great interest in the field of electrochromic (EC) due to its abundance of color variations. However, there are still a series of problems such as slow ion diffusion, poor electronic conductivity and cyclic stability in the reaction process. Herein, we successfully prepared a stable and fast multi-color electrochromic material V2O5-PEDOT by a simple "one-pot" method. The layer space of V2O5 could be tuned by 3,4-ethylenedioxythiophene (named V2O5-PEDOT) during the dissolution and recrystallization of vanadium oxide. The expanded layer spacing facilitates rapid ion insertion and extraction. PEDOT serves as an internal conductive pillar to improve the overall conductivity of the material. The obtained intercrossing structure of the nanobelts shortens the ion diffusion distance and ensures electrolyte penetration. The V2O5-PEDOT exhibits the fast response time (1.1 s for coloration and 3.5 s for bleaching at 422 nm), high optical contrast (ΔT = 45% at 422 nm and ΔT = 35.2% at 1000 nm), great coloration efficiency (CE = 97.1 cm2/C), and high cyclic stability (86% preserved after 3000 cycles). The electrochromic devices (ECD) were successfully assembled by using V2O5-PEDOT films as ion storage layers and electrochromic layers, demonstrating remarkable performance.
Highly selective and remotely communicable nitrogen dioxide (NO2) sensing may contribute to future Internet of Things in environmental monitoring. However, room-temperature NO2 sensing materials such as carbon materials is still less than satisfactory due to their insensitive interaction with target gas. Here, polyethylene imine functionalized three-dimensional (3D) carbon framework (PEI/C framework) has been developed for enhanced selective NO2 sensing, via combined template synthesis and subsequent doping. Typically, the 3D PEI/C framework is observed porous shape with irregular coating. Beneficially, the response of C framework to NO2 increases while those of interfering gases decrease after being functionalized with PEI. Remarkably, the sensor prototypes show a 100 ppb-concentration detection limit at room temperature. Theoretically, such excellent NO2 sensing is attributed to the large specific surface ratio of porous 3D PEI/C framework, in which PEI serves as an active layer for target NO2, while a passivated one for interfering gases. Practically, such PEI/C framework sensor prototype is simulated for NO2 sensing device and communicated with a smartphone, showing great potential in future intelligent environmental monitoring.
Direct X-ray detectors, which directly convert X-rays into electrical signals through semiconductors, have higher space solution than scintillator-mediated indirect X-ray ones and are high desirable for early cancer detection and other applications, but the mainstream commercial α-Se detector is still largely limited by high production costs, large leakage current and low stability. This article reports an easily prepared, stable radiochromic semiconductive metal–organic framework (MOF), (MV)[Cd3(tdc)4]·2H2O (RCS-1, H2tdc = 2,5-thiophenedicarboxylic acid; MV2+ = methyl viologen cation) with direct X-ray detecting ability. With a large bulk resistivity of 8.40 × 109 Ω cm, this material ensures minimal dark current and low noise for X-ray detection. Additionally, it exhibits higher sensitivity to W Kα X-rays (98.58 µC Gy−1 cm−2) than α-Se (~20 µC Gy−1 cm−2). Meanwhile, unlike most reported direct X-ray detecting semiconductors, compound RCS-1 shows remarkable color change upon X-ray irradiation owing to the presence of photochromism-active viologen cations. This feature offers an appealing visual detecting ability to direct X-ray detectors that provide only the electrical signals.
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