Latest ArticlesChemoselective amine bioconjugation has long been a challenge for native protein modification. Inspired by Thiele's seminal discovery, Li and co-workers recently developed an ortho-phthalaldehyde (OPA) based reagent for labeling the amino group of a protein. Here we report an expeditious and scalable synthesis of a Li—Thiele reagent featuring an arene construction strategy. The reagent contains an alkyne side chain as a handle for secondary modification.
Light utilization is one of the key factors for the improvement of photocatalytic performance. Herein, we design C-TiO2 hollow nanoshells with strong Mie resonance for enhanced photocatalytic hydrogen evolution in a dye-sensitized system under visible light irradiation (λ≥420 nm). By tuning the inner diameters of hollow nanoshells, the Mie resonance in hollow nanoshells is adjusted for better excitation of dye molecules, which thus greatly enhances the light utilization in visible light region. This work shows the potential of Mie resonance in nanoshells can be an alternative strategy to increase the light utilization for photocatalysis.
The Platinum (Pt)-based catalysts exhibit excellent catalytic performance for the hydrogen evolution reaction (HER) while suffering from poor stability due to the weak interaction between the carbon support and Pt. Herein, a molybdenum-doped titanium dioxide (Ti0.9Mo0.1O2) supported low-Pt electrocatalyst with stronger interaction between catalyst and support is applied to tune the electrocatalytic performance of Pt. The Ti0.9Mo0.1O2 support can not only tolerate the corrosion environment in the catalytic system, but also generate strong metal-support interaction (SMSI) between the oxide and catalyst. A facile solvothermal method is used to prepare Ti0.9Mo0.1O2 as support to anchor Pt nanoparticles. The 5% Pt supported on Ti0.9Mo0.1O2 catalyst exhibits 4.4-fold mass activity (MA) at an overpotential of 50 mV and higher stability than 20% Pt/C with only 1/4 Pt loading. The SMSI between the Ti0.9Mo0.1O2 and Pt prevents the Pt aggregation to achieve excellent stability, and hydrogen spillover effect in the interface between Pt and support benefits the hydrogen production process. This work presents a novel sight for the fabrication and design of oxide supported catalysts in various catalytic system by reasonably employing support effect.
Ion diffusion kinetics, depending on the size, tortuosity, connectivity of the channels, greatly affects the rate performance of the electrodes. Two-dimensional materials (2DMs) has emerged as promising electrode materials in the past decades. However, the applications of 2DMs electrodes are limited by the strong restacking problem, which leads to a poor rate capability. In this work, we for the first time mediated the morphology of molybdenum disulfide (MoS2) nanosheets via a facile coagulation method; abundant sheet crumples were induced, which greatly enhance their surface accessibility and thus benefit the ion diffusion kinetics. Consequently, the crumpled-MoS2 electrodes follow a capacitive Na-ion charge-storage mechanism to a large extent. Importantly, we demonstrate the special role of organic cations in the inter-sheet assembly configuration, in sharp contrast with that of alkali/alkaline-earth ones. We propose that organic cations cause edge/face contact of the sheets, instead of the face/face contact, thus affording a house-of-cards structure.
Metal-free heteroatoms dual-doped carbon has been recognized as one of the most promising Pt/C-substitutes for oxygen reduction reaction (ORR). Herein, we optimize the preparation process by doping order of metal-free heteroatoms to obtain the best electrocatalytic performance through three types of dual-doped carbon, including XC-N (first X doping then N doping), NC-X (first N doping then X doping) and NXC (N and X doping) (X = P, S and F). XC-N has more defect than the other two indicated by Raman spectra. X-ray photoelectron spectrom (XPS) measurements indicate that N and X have been dual-doped into the carbon matrix with different doping contents and modes. Electrocatalytic results, including the potential of ORR peak (Ep), the half-wave potential, the diffusion-limiting current density mainly follows the order of XC-N > NC-X > NXC. Furthermore, the synergistic effect of second atom doping are also compared with the single doped carbon (NC, PC, SC and FC). The differences in electronegativity and atomic radius of these metal-free heteroatoms can affect the defect degree, the doping content and mode of heteroatoms on carbon matrix, induce polarization effect and space effect to affect O2 adsorption and product desorption, ultimately to the ORR electrocatalytic performance.
Plant polyphenol-based coordination polymers (CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applications, but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. Herein, a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species (e.g., Gd, Cu, Ni, Zn, Fe) and ultra-small diameter (8.6–37.8 nm) using nontoxic plant polyphenol (e.g., tannic acid, gallic acid) as a polymerizable ligand. Polyphenol molecules react with formaldehyde firstly, which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal nanoparticles. These ultrafine nanoparticles with stably chelated metal ions are highly water dispersible and thus advantageous for bioimaging. As an example, ultra-small Gd contained CPs exhibit higher longitudinal relaxivity (r1 = 25.5 L mmol-1 s-1) value with low r2/r1 (1.19) than clinically used Magnevist (Gd-DTPA, r1 = 3.7 L mmol-1 s-1). Due to the enhanced permeability and retention effect, they can be further used as a positive contrast agent for T1-weighted MR imaging of tumour.
Herein, we report a microwave-assisted acid-induced post-treatment method for the formation of linker vacancies within Zr-based metal organic frameworks (Zr-MOFs). The number of linker vacancies can be easily regulated with this method by changing the concentration of the HCl solution and the duration of microwave irradiation. The optimized defective UiO-66 showed higher linker defects with a higher specific surface area and thermal stability. The results of the catalytic cyclization of citronella showed that the Zr-MOFs with more defects exhibited enhanced catalytic performance. This work may provide a new method for the creation of defective MOFs with high activity and stability.
Research on pollution characteristics and toxicities of emerging polycyclic aromatic sulfur heterocycles (PASHs) in PM2.5 has not been reported due to the lack of analytical method with the needed performance. In the present study, a novel method for the determination of 14 PASHs in PM2.5 was developed using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). Atmospheric pressure chemical ionization was operated with multiple reaction monitoring in positive ionization mode. High sensitivity (method detection limit < 1.673 pg/m3), acceptable recoveries (67.6%–120.8%) and precisions (RSD of 2.2%–15.4%) were obtained. The method was successfully applied for analyzing PASHs in 10 PM2.5 samples collected from Taiyuan, a typical industrial city in China, in 2016. The total concentrations were from 929 pg/m3 to 14,593 pg/m3. The determined levels indicated that further investigations on environmental fate and toxicities of PM2.5-bound PASHs may be needed.
Herein, we propose a novel photoelectrochemical (PEC) biosensor for dual microRNAs (miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification (SDA) reaction. The recognition of HmiR-21 and Hlet-7a by microRNA-21 and let-7a leads to their change in hairpin structures, subsequently initiating the immobilization of abundant CdS quantum dots (CdS QDs) and methylene blue (MB) based on SDA reaction. The immobilized CdS QDs and MB produce both high PEC currents under 430 nm light and 627 nm light illumination, respectively, and the generated PEC currents are closely relied on target miRNAs amounts. Thus, highly sensitive and simultaneous detection of microRNA-21 Herein, we propose a novel photoelectrochemical (PEC) biosensor for dual microRNAs (miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification (SDA) reaction. The recognition of HmiR-21 and Hlet-7a by microRNA-21 and let-7a leads to their change in hairpin structures, subsequently initiating the immobilization of abundant CdS quantum dots (CdS QDs) and methylene blue (MB) based on SDA reaction. The immobilized CdS QDs and MB produce both high PEC currents under 430 nm light and 627 nm light illumination, respectively, and the generated PEC currents are closely relied on target miRNAs amounts. Thus, highly sensitive and simultaneous detection of microRNA-21 and let-7a was readily achieved with detection limit at 6.6 fmol/L and 15.4 fmol/L based on 3σ, respectively. Further, this PEC biosensor was applied in simultaneous analysis of miRNA-21 and let-7a in breast cancer patient's serum with acceptable results. We expect this biosensor will find more useful application in diagnosis of miRNA-related diseases.
Fe-based phosphates with excellent physical and chemical features are potential electrode materials for supercapacitors. In this work, we successfully synthesized Fe-based phosphates with different dimensions, morphologies, and compositions by one-step hydrothermal method. Influence factors on the chemical composition and morphology of the as-prepared materials were explored and the energy storage performance of the as-prepared samples were tested under the traditional three electrode system. Two-dimensional (2D) iron metaphosphate (Fe(PO3)3) showed the best electrochemical performance. For Fe(PO3)3 electrode materials, the layered structure can provide a larger specific surface area than the bulk structure, which is conducive to the diffusion and transport of electrolyte ions during charging-discharging and further improves the rate performance and cycle stability of supercapacitor. 2D Fe(PO3)3 and activated carbon were used as electrode materials to construct a 2D Fe(PO3)3//AC supercapacitor. The supercapacitor showed high energy density, high power density, and excellent cycling stability, which indicates 2D Fe(PO3)3 is a promising electrode material for supercapacitors.
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