Latest ArticlesIn this paper, a hydrothermal approach is utilized for the first time in integrating graphene oxide (GO), acetic acid (HAc) and nickel foam to prepare hydrogenated graphene (HG). There are two primary aims of this study: one is to ascertain the structure of the as-prepared HG, and the other one is to investigate the ferromagnetism of the HG. Under hydrothermal conditions, GO was reduced and hydrogenated by HAc, while the nickel foam served as a catalyst. This work provides a novel and facile route for the synthesis of hydrogenated graphene, which may lead to the application of hydrogenated graphene in spin electronic devices.
The angle dependence of photonic crystals (PCs) dramatically limits their practical applications in the colorimetrical sensing of humidity and volatile organic compound (VOC) vapors. In addition, it is challenging for inverse opal PCs to colorimetrically distinguish between vapors with similar refractive indices. Different from the mechanism of PC-based sensors, here, we report an angle-independent polyacrylamide (PAAm) organogel structural color film based on the mechanisms of retroreflection, total internal reflection (TIR) and interference with a shape similar to a single-sided "egg waffle". During the process of responding to humidity and VOC vapors, the color of the film remains angle-independent in the normal angle range of 0° to 45° under coaxial illumination and observation conditions. At the same time, the film can colorimetrically distinguish between vapors with similar refractive indices, such as methanol and ethanol, which is mainly due to the differences in their polarity and solubility parameters. The film shows good stability, reversibility and selectivity when exposed to vapors. A colorimetric sensor with a new response mechanism is proposed and has the potential to effectively distinguish between vapors with similar refractive indices. Furthermore, this responsive retroreflective structural color film (RRSCF) provides a universal strategy to develop targeted angle-independent structural color sensors by selecting optimized materials.
An efficient approach to functionalized 4, 6-disubstituted-and 4, 6, 6-trisubstituted-1, 3-oxazinan-2-ones skeleton has been developed through the reaction of semicyclic N, O-acetals 4a and 4b with 1, 1- disubstituted ethylenes 5 or 8. As a result of such a [4 + 2] cycloaddition process, 4, 6, 6-trisubstituted- 1, 3-oxazinan-2-ones 6aa, 6af-6au, 7ba, 7bf-7bw and 6, 6-spiro containing 1, 3-oxazinan-2-ones 9ad, 9ae, 10ba-10bg were obtained in 36%-96% yields and with moderate to excellent diastereoselectivities. In addition, the synthesis of (±)-norallosedamine 12 could be conveniently achieved from the cycloadduct 7bf.
Potassium-ion batteries (KIBs) have become the most promising alternative to lithium-ion batteries for large-scale energy storage system due to their abundance and low cost. However, previous reports focused on the intercalation-type cathode materials usually showed an inferior capacity, together with a poor cyclic life caused by the repetitive intercalation of large-size K-ions, which hinders their practical application. Here, we combine the strategies of carbon coating, template etching and hydrothermal selenization to prepare yolk-shelled FeSe2@N-doped carbon nanoboxes (FeSe2@C NBs), where the inner highly-crystalline FeSe2 clusters are completely surrounded by the self-supported carbon shell. The integrated and highly conductive carbon shell not only provides a fast electron/ion diffusion channel, but also prevents the agglomeration of FeSe2 clusters. When evaluated as a conversion-type cathode material for KIBs, the FeSe2@C NBs electrode delivers a relatively high specific capacity of 257 mAh/g at 100 mA/g and potential platform of about 1.6 V, which endow a high energy density of about 411 Wh/kg. Most importantly, by designing a robust host with large internal void space to accommodate the volumetric variation of the inner FeSe2 clusters, the battery based on FeSe2@C NBs exhibits ultra-long cycle stability. Specifically, even after 700 cycles at 100 mA/g, a capacity of 221 mAh/g along with an average fading rate of only 0.02% can be retained, which achieves the optimal balance of high specific capacity and long-cycle stability.
Surface oxidized iron-nickel nanorods coupling with reduced graphene architectures (FeNi-O-rGA) are successfully constructed via hydrothermal, freeze-drying, and thermal activation approaches. The hierarchical structure can provide lots of pathways for fast ion diffusion and charge transfer, and expose abundant catalytic sites. Meanwhile, the activity of FeNi-O-rGA is boosted by the optimized metal-oxygen bond strength in FeNi3 alloys. Partial oxidized FeNi nanorods are strongly coupled with rGA by the formation of metal-O-C bonds, which can impede the aggregation of FeNi3 alloys and increase the utilization of active sites. The special structure and partially oxidized FeNi nanorods for FeNi-O-rGA can result in excellent OER activity and catalytic stability. Only 215 mV of overpotential is required to drive the current density of 10 mA/cm2 as well as the Tafel slope of 50.9 mV/dec in 1 mol/L KOH. The change of surface chemistry of FeNi-O-rGA is confirmed by XPS after the OER test, which indicates the highly catalytic stability of FeNi-O-rGA due to the formation of intermediate metal oxyhydroxide.
A new charge transfer cocrystal of 1, 2, 4, 5-tetracyanobenzene (TCNB)-phenazine (PTC) was prepared by solvent evaporation method. The donor and acceptor molecules of cocrystal are stacked face to face with a mixed-stacking, implying a strong charge transfer (CT) interactions in the cocrystal system. The spectroscopic studies, single-crystal X-ray diffraction structure, density functional theory (DFT) and Hirschfield surfaces calculations are carried out to explore the relationship between structure and properties of cocrystal system, which show that the intermolecular interactions in PTC are stronger than those of single components, leading to the stability and photophysical behaviors of cocrystal different from their constitute units. This study will be helpful for the design and preparation of multifunctional cocrystal materials.
The widespread applications of aggregation-induced emission luminogens (AIEgens) inspire the creation of AIEgens with novel structures and functionalities. In this work, we focused on the direct and efficient synthesis of a new type of AIEgens, imidazo[1, 5-a]pyridicne derivatives, via iodine mediated cascade oxidative Csp2–H or Csp–H amination route from phenylacetylene or styrenes under mild conditions. The resulted compounds showed excellent AIE characteristics with tunable maximum emissions, attractive bioimaging performance, and potential anti-inflammatory activity, which exert broad application prospects in material, biology, medicine, and other relevant areas.
Carbon-based selenium-containing materials are novel materials just being invented recently. Owing to the low cost and bio-compatible features of carbon and selenium, these materials are practical. The unique chemical- and bio-activities of selenium endow them wide range of applications in catalysis, environment-protection, fertilizer and biocide development etc. Recent progresses in this field are summarized and prospected from the engineering application viewpoint in this mini-review.
Ozone (O3) plays essential roles in stratosphere and helps reduce the amount of harmful ultraviolet arriving the Earth's surface. However, O3 is also a strong oxidant and causes troubles to human health in troposphere, especially in the confined space, such as indoor environment. Recently, O3 abatement materials have become research hotspots due to the urgent environmental demands. Catalysis is a facile strategy that can eliminate indoor airborne O3 efficiently and economically. Thus, this review summarizes the recent progresses of O3 decomposition catalysts. The catalysts covered here are categorized as follows: zeolite, metal organic frameworks (MOFs), metal oxides, noble metals. Manganese-based catalysts display higher efficiency and are mainly discussed. Generally, the active sites of O3 decomposition catalysts are described as Lewis acid sites (e.g., zeolite), metal sites (e.g., MOFs), oxygen vacancy sites (e.g., MnO2) in the previous work. In this review, we ascribe all the active sites to unsaturated metal sites and their Lewis acidity. Possible evidence from the experimental and theoretical perspectives are proposed. Furthermore, the strategy to circumvent deactivation caused by peroxides (O22-) accumulation and water molecular competition are also elaborated. Finally, perspective is presented on the challenges and opportunities of exploring existing and new O3 decomposition catalysts.
In this research, a novel bird nest-like zinc oxide (BN-ZnO) nanostructures were prepared by a simple solvothermal method. A sensitive electrochemical glucose biosensor was for the first time developed based on the immobilization of glucose oxidase (GOx) on nanostructured BN-ZnO modified electrode. The BN-ZnO nanostructure and the resultant biosensor were characterized by scanning electron microscope, X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. BN-ZnO nanostructures have large specific surface area and can load large amounts of GOx molecules. Meanwhile, BN-ZnO provides an excellent microenvironment to retain the native bioactivity of enzymes and to promote direct electron transfer between GOx and electrode surface. The proposed biosensor shows a wide linear range of 0.005–1.6 mmol/L, high sensitivity of 15.6 mAL mol−1 cm−2 with a low detection limit of 0.004 mmol/L. The resulting biosensor also shows excellent selectivity, acceptable stability and reproducibility, and can be successfully applied in the detection of glucose in human serum samples at −0.37V.