Latest ArticlesThe rapid development of next-generation flexible electronics stimulates the growing demand for flexible and wearable power sources with high energy density. Li metal capacitor (LMC), combining with a Li metal anode and an activated carbon cathode, exhibits extremely high energy density and high power density due to the unique energy storage mechanism, thus showing great potential for powering wearable electronic devices. Herein, a flexible LMC based on an in situ prepared PETEA-based gel polymer electrolyte (GPE) was reported for the first time. Owing to the high ionic conductivity of PETEA-based GPE (5.75 × 10-3 S/cm at 20 ℃), the assembled flexible LMC delivers a high capacitance of 210 F/g at 0.1 A/g within the voltage range from 1.5 V to 4.3 V vs. Li/Li+, a high energy density of 474 Wh/kg at 0.1 A/g and a high power density of 29 kW/kg at 10 A/g. More importantly, PETEA-based GPE endows the LMC with excellent flexibility and safety, which could work normally under abuse tests, such as bending, nail penetration and cutting. The in situ prepared PETEA-based GPE simplifies the fabrication process, avoids the risk of leakage and inhibits the growth of Li dendrite, making LMC a promising flexible energy storage device for the flexible electronic field.
A facile approach was successfully employed to prepare Fe2O3/Co3O4 nanosheet arrays on nickel foams (Fe2O3/Co3O4@NF), which owned such advantages as narrow band gap energies and high separation rate of photoexcited electron-hole pairs. The combination of Fe2O3 and Co3O4 dramatically enhanced the photocatalytic activity towards sulfamethoxazole (SMZ) degradation, with the highest catalytic efficiency of k = 0.0538 min−1, which was much higher than that of Fe2O3@NF (0.0098 min−1) and Co3O4@NF (0.0094 min−1). The introduction of Ni foam could not only act as the support to anchor photocatalyst, but also work as the electron mediator to promote the transition of electron-hole pairs. Reactive species trapping experiments combined with electron paramagnetic resonance analysis confirmed ·O2− was primarily responsible for SMZ degradation. Furthermore, Fe2O3/Co3O4@NF was effective and almost unaffected by inorganic cations and anions in aqueous solution. This study could provide a facile and promising path for the construction of self-supported metal oxide-based heterojunction with high efficiency and strong stability.
Dopamine (DA) is easy to be oxidized and polymerizes to form polydopamine (pDA) in alkaline conditions, while the synthesis is usually time-consuming (48 h). Herein, the polymerization of DA is completed with 4 h under the catalysis of acid phosphatase (ACP). The high efficiency makes the detection of DA feasibility based on the self-polymerization of DA. In this assay, pDA is grown in situ on the surface of covalent organic frameworks (COFs), and then the fluorescence of COFs is quenched significantly. The linear range of DA is achieved from 0.5–50 μmol/L with a detection limit of 0.16 μmol/L. The detection of DA is not interfered with uric acid, ascorbic acid, and some phenolic compounds, because these substances cannot polymerize in the presence of ACP. Moreover, benefiting from the good sensitivity and selectivity, DA has been successfully determined by this strategy in human urine samples with satisfactory recoveries.
Spatial isolation of different functional sites at the nanoscale in multifunctional catalysts for steering reaction sequence and paths remains a major challenge. Herein, we reported the spatial separation of dual-site Au and RuO2 on the nanosurface of TiO2 (Au/TiO2/RuO2) through the strong metal-support interaction (SMSI) and the lattice matching (LM) for robust photocatalytic hydrogen evolution. The SMSI between Au and TiO2 induced the encapsulation of Au nanoparticles by an impermeable TiOx overlayer, which can function as a physical separation barrier to the permeation of the second precursor. The LM between RuO2 and rutile-TiO2 can increase the stability of RuO2/TiO2 interface and thus prevent the aggregation of dual-site Au and RuO2 in the calcination process of removing TiOx overlayer of Au. The photocatalytic hydrogen production is used as a model reaction to evaluate the performance of spatially separated dual-site Au/TiO2/RuO2 catalysts. The rate of hydrogen production of the Au/TiO2/RuO2 is as high as 84 μmol h−1g−1 under solar light irradiation without sacrificial agents, which is 2.5 times higher than the reference Au/TiO2 and non-separated Au/RuO2/TiO2 samples. Systematic characterizations verify that the spatially separated dual-site Au and RuO2 on the nanosurface of TiO2 can effectively separate the photo-generated carriers and lower the height of the Schottky barrier, respectively, under UV and visible light irradiation. This study provides new inspiration for the precise construction of different sites in multifunctional catalysts.
In this work, hollow Fe2O3/Co3O4 microcubes have been successfully synthesized through a hydrothermal method followed by an annealing process using metal-organic framework of Prussian blue as a soft template. The morphologies, microstructures, surface area and element compositions have been carefully characterized by a series of techniques. Meanwhile, compared with that of pure Fe2O3 and Co3O4, the gas sensor based on the hollow microcubes exhibits enhanced sensing performances towards acetone, e.g., a higher response of 21.2 and a shorter response time of 5 s towards 20 ppm acetone at a relatively low working temperature of 200 ℃. Moreover, the hollow microcubes-based gas sensor still shows perfect long-term stability, excellent repeatability and the ability of sub-ppm level detection, which provides a possibility for its application in real life. The enhanced gas sensing performances can be attributed to the hollow structure with a high surface area and the formed p-n heterojunctions within the microcubes.
Up to date, solid-state carbon dots (CDs) with bright red fluorescence have scarcely achieved due to aggregation-caused quenching (ACQ) effect and extremely low quantum yield in deep-red to near infrared region. Here, we report a novel fluorine-defects induced solid-state red fluorescence (λem = 676 nm, the absolute fluorescence quantum yields is 4.17%) in fluorine, nitrogen and sulfur co-doped CDs (F, N, S-CDs), which is the first report of such a long wavelength emission of solid-state CDs. As a control, CDs without fluorine-doping (N, S-CDs) show no fluorescence in solid-state, and the fluorescence quantum yield/emission wavelength of N, S-CDs in solution-state are also lower/shorter than that of F, N, S-CDs, which is mainly due to the F-induced defect traps on the surface/edge of F, N, S-CDs. Moreover, the solid-state F, N, S-CDs exhibit an interesting temperature-sensitive behavior in the range of 80-420 K, with the maximum fluorescence intensity at 120 K, unveiling its potential as the temperature-dependent fluorescent sensor and the solid-state light-emitting device adapted to multiple temperatures.
An efficient and practical methods for the synthesis of carbamoyl quinoline-2, 4-diones via the reaction of ortho-cyanoarylacrylamides with oxamic acids was described. This cyclic reaction could be performed efficiently under metal free conditions. Various products with functional groups could be obtained with moderate to high yields via radical mechanism.
Whilst most bioorthogonal reactions focus on targeting binding-site cysteine residues, proximity-induced reactivity effect ensures that reaction also occurs at nucleophilic lysine residues. We report one example here that the propargylated-sulfonium center undergoes a nucleophilic reaction with lysine residue via proximity-induced conjugation. This propargylated-sulfonium tethered peptide resulting from a facile propargylation of thiolethers, enables amino-yne reaction at the selected lysine on MDM4 protein. This strategy represents a viable approach of lysine-targeted covalent inhibition in proximity.
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.
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