Latest ArticlesWater splitting by photoelectrochemical (PEC) processes to convert solar energy into hydrogen energy using semiconductors is regarded as one of the most ideal methods to solve the current energy crisis and has attracted widespread attention. Herein, Co-based metal-organic framework (Co(bpdc)(H2O)4 (Co-MOF) nanosheets as passivation layers were in-situ constructed on the surface of BiVO4 films through an uncomplicated hydrothermal method (Co-MOF/BiVO4). Under AM 1.5G illumination, synthesized Co-MOF/BiVO4 electrode exhibited a 4-fold higher photocurrent than bare BiVO4, measuring 6.0 mA/cm2 at 1.23 V vs. RHE in 1 mol/L potassium borate electrolyte (pH 9.5) solution. Moreover, the Co-MOF/BiVO4 film demonstrated a 96% charge separation efficiency, a result caused by an inhibited recombination rate of photogenerated electrons and holes by the addition of Co-MOF nanosheets. This work provides an idea for depositing inexpensive 2D Co-MOF nanosheets on the photoanode as an excellent passivation layer for solar fuel production.
Realizing both a high emission efficiency and luminescence dissymmetry factor (glum) in circularly polarized solution processable organic light-emitting diodes (CP-OLEDs) remains a significant challenge. In this contribution, two chiral phosphorescent liquid crystals based on cyclometalated platinum complexes are prepared, in which the chiral s-2-methyl-1-butyl group is introduced into the cyclometalating ligand and the mesogenic fragment is attached to the periphery of the ancillary ligand. The platinum complexes exhibit both smectic and chiral nematic phases as evidenced by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray diffraction. Remarkably, a high photoluminescent quantum efficiency of over 78% and clear circularly polarized luminescent signal with gPL of about 10–2 are observed for the complexes. Further, solution-processed CP-OLEDs show maximum external quantum efficiencies (EQE) of over 15% and strong circularly polarized electroluminescent signals with a gEL ≈ 10–2. This research demonstrates that both liquid crystallinity and the number of chiral centers play key roles in improving the chiroptical property, paving the way for a new approach for the design of high-efficiency CPL emitters.
Designing single-atom nanozymes with densely exposed metal atom active sites and enhancing catalytic activity to detect pollutants remain a serious challenge. Herein, we reported a single-atom nanozyme with layered stacked Fe/Cu dual active sites (Fe/Cu-NC SAzyme) synthesized via hydrothermal and high-temperature pyrolysis using folic acid as a template. Compared with Fe-NC and Cu-NC SAzyme, Fe/Cu-NC SAzyme has higher peroxidase-like activity, which indicates that the doping of synthesized Fe/Cu bimetals can improve the catalytic activity and that the atomic loading of Fe and Cu in Fe/Cu-NC is 5.5 wt% and 2.27 wt%, respectively. When S2− is added to the Fe/Cu-NC catalytic system, a high-sensitivity and high-selectivity S2− colorimetric sensing platform can be established, with a wide linear range (0.09–6 µmol/L) and a low detection limit (30 nmol/L), which can be used to detect S2− in environmental water samples. What's more, the Fe/Cu-NC SAzyme can activate peroxymonosulfate (PMS) to degrade 99.9% of rhodamine B (RhB) within 10 min with a degradation kinetics of 0.5943 min−1. This work details attractive applications in Fe/Cu-NC SAzyme colorimetric sensing and dye degradation.
Microneedles are considered to be an effective, convenient, non-invasive, biosafety and compliant medical technology for vaccinations, biomarker testing, medical aesthetics and other related fields. Nonetheless, further clinical and commercial translation of regular microneedles is hampered by challenges in manufacturability, cost variability, insufficient comfort, contamination and so on. Recent innovations in functional biomaterials and chemical engineering technologies have been applied to develop extensible and swellable hydrogel-forming microneedles, achieving precise and controlled drug delivery and localized sampling from the target tissues. In this review, we systematically summarize the latest development of the extensible and swellable hydrogel-forming microneedles, including deep point-of-care testing, drug deployment, wound healing and mucoadhesion improvement. In addition, further analysis of the challenges and prospects for clinical application of current strategies is well presented. It is believed that the combined efforts of engineering, material, pharmaceutical and clinical research will contribute to the future success of this clinical and commercial translation.
Levofloxacin (LVFX) as a representative drug of quinolone antibiotics is widely used in clinical, and its residues enriched in water bodies and sideline products seriously damage human health. It is imperative to develop a real-time/on-site sensing method for monitoring residual antibiotics. Here, we report a portable sensing platform by utilizing a composite fluorescent nanoprobe constructed by the cerium ions (Ce3+) coordination functionalized CdTe quantum dots (QDs) for the visual and quantitative detection of LVFX residues. This fluorescent probe provides a distinct color variation from red to green, which shows a good linear relationship to LVFX residues concentrations in the range of 0-6.0 µmol/L with a sensitive limit of detection (LOD) of 16.3 nmol/L. The smartphone platform with Color Analyzer App installed, which could accomplish quantified detection of LVFX in water, milk, and raw pork with a LOD of 27.9 nmol/L. The facile sensing method we proposed realizes rapid visualization of antibiotics residual in the environment and provides a practical application pathway in food safety and human health.
The NO gas is easily oxidized to form toxic by-products (NO2) during the oxidation process, which are adsorbed on the catalyst surface and inhibit the subsequent reaction. For photocatalytic NO removal, a significant challenge is to achieve catalytic stability while maintaining high conversion efficiency. Here, we fabricated a (BiO)2CO3/β-Bi2O3 heterostructure that enables efficient charge transfer and promotes the NO removal. We propose that the catalytic stability depends on the heterojunction structure, which is able to generate interfacial charge transfer channels. In addition, we further introduce graphene quantum dots on the heterojunction structure, which further strengthens the interfacial charge transfer dynamics and finally realizes that the NO2 byproduct could gain electrons and convert to the final product (nitrite or nitrate). This composite structure not only exhibits high activity for NO removal but also maintains long-term stability under visible light.
Heterogeneous Fenton has been widely used in the disposal of organic pollutants, however, slow regeneration of Fe(Ⅱ) remains limitation for its practical application of long-term treatment. Herein, we come up with a novel Fe-based heterogeneous Fenton catalyst named as FeSxOy-X (X is the ratio of ethylene glycol to N, N-dimethylformamide). With the help of the abundant defect electrons in Sulfur vacancies, Fe(Ⅱ) regeneration on the surface of FeSxOy-1:1 was accelerated, resulting in a stable proportion of Fe(Ⅱ) on the surface, which maintained continuously stable generation of hydroxyl radical (•OH) and singlet oxygen (1O2). Thus, without any organic reagents or cocatalysts, FeSxOy-1:1 based Fenton system achieved effective long-term degradation of 560 mg/L quinoline within only 7 days, which was evidently better than reported FeS and SV-FeS2 (SV: Sulfur vacancy). The system had excellent adaptability to water quality and the COD removal rate of biochemical wastewater was as high as 79.8%.
Atmospheric pollutants can deteriorate air quality and put human health at risk. There is a growing need for green, economical, and efficient technologies, among which catalytic elimination technology is the most promising, to remove atmospheric pollutants. Two-dimensional transition metal oxides (2D TMOs) have recently become attractive catalysts due to their highly exposed active sites, excellent reactant transport properties, and extraordinary catalytic performance. This review systematically summarizes the top-down and bottom-up preparation methods of 2D TMOs and focuses on the specific applications of 2D TMOs in the catalytic elimination of atmospheric inorganic pollutants and volatile organic pollutants. The development of 2D TMOs in the catalytic elimination of atmospheric pollutants is prospected. This review is expected to provide design insights into efficient 2D TMOs to remove atmospheric pollutants.
A new Rh(Ⅲ)-catalyzed aldehydic C-H activation/[4 + 3] annulation cascade of N-sulfonyl-2-aminobenzaldehydes with gem-difluorocyclopropenes is reported for the first time, and used to produce a range of hitherto unreported precedented β-monofluorinated benzo[b]azepin-5-ones with good yields and complete regioselectivity. This approach features a broad substrate scope, good functional group tolerance, and high regioselectivity, which may include Rh(Ⅲ)-catalyzed aldehydic C−H activation, tandem site-/regioselective insertion, defluorinated ring-scission, and 1, 2-elimination.
The co-crystallization of quercetin (Qur) with a flexible molecule 4-(4-pyridinyldisulfanyl) pyridine (DPDS) in different solvents and conditions was investigated, yielded five multi-component crystalline phases and characterized with X-ray diffractions and thermal analysis. Although the crystal system of Qur-DPDS-MeOH and Qur-DPDS-Dioxane is the same, the desolvation results revealed that Qur-DPDS-MeOH transformed to Qur-DPDS when MeOH solvent molecules escape from the lattice, while Qur-DPDS-Dioxane transformed to Qur-DPDS-Ⅱ through a similar process, which is same with Qur-DPDS-THF. These two cocrystal polymorphs Qur-DPDS and Qur-DPDS-Ⅱ obey an enantiotropic relationship. Moreover, the formation of cocrystal solvates improves the packing efficiency of crystals. Crystal structure analysis showed that hydrogen bonds and conformations of the corresponding parent molecules play a major role in molecular assembly and crystal packing patterns, thus bring different physicochemical properties. Finally, the fluorescence spectra and quantum-chemical calculations were carried out to explore the difference in the optical-physical properties.
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