It was found that 3,4-dihydroxybenzoic acid (protocatechuric acid) inhibited chemiluminescence of luminol-H2O2 reaction catalyzed by Co2+. On this basis, a flow injection method has been developed for the determination of protocatechuric acid. The method is simple, convenient and sensitive with detection limit of 2.7 x 10(-7) mol/L and is effective to determine protocatechuric acid in the range of 1 x 10(-6)-1 x 10(-5) mol/L. The variation coefficient of eleven determinations for 8 x 10(-6) mol/L protocatechuric acid is 2.3%.
A sensitive electrochemical sensor was fabricated based on two dimensional (2D) MoS2 nanosheets (MoS2), gold nanoparticles (AuNPs) and polypyrrole (PPY) nanocomposite modified glass carbon electrode (GCE) for glucose detection. Liquid phase exfoliation (LPE) method was applied for the synthesis of 2D MoS2 nanosheets using N, N-dimethylformamide (DMF). The fabrication of sensor involved the electrochemical deposition of AuNPs on GCE using cyclic voltammetry (CV) followed by drop-casting of 2D MoS2 nanosheets to prepare MoS2-AuNPs/GCE electrode. Pyrrole was then electropolymerized on MoS2-AuNPs/GCE surface using amperometry. The structural properties of prepared nancomposites were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and fourier transform infra red (FTIR) spectroscopic techniques. The prepared MoS2-PPY-AuNPs/GCE electrode was applied for electrochemical sensing of glucose by differential pulse voltammetry (DPV) in NaOH solution. Cu(II)/Cu(III) redox couple was utilized as catalytic center which converted glucose into gluconolactone at an oxidation potential of +0.45 V. The fabricated electrode showed a detection limit (LOD) of 0.08 nM and a quantification limit (LOQ) of 0.26 nM. Furthermore, it exhibited high reproducibility (2.48%), long term stability and high selectivity toward glucose detection. The electrode was found suitable for glucose detection in human serum samples with recoveries ranging from 97%–102.1%.
Co/Mn-MOFs-1-1-150, a two-dimensional sheet-like bimetallic Co/Mn-based MOF with peroxidase-like activity, efficiently accelerates the oxidation of TMB in the presence H2O2.
A new diterpenoid named jatrophacine (1), with an unusual 4,5-seco- rhamnofolane skeleton, was isolated from the roots of Jatropha curcas, together with eleven known diterpenoids. The structure of the new compound was elucidated through a detailed analysis of its 1 D- and 2 D-NMR spectra. The X-ray structure of jatrophol (2) is also presented. Anti-inflammatory activity with LPS-induced RAW 264.7 macrophages revealed that compound 1 strongly inhibited the production of nitric oxide (IC50 = 0.53 μM).
Abstract Designing stable, low‐cost yet highly active electrocatalysts is crucial for overall water splitting, representing a promising approach for clean energy generation. In this work, periodic density functional theory calculations are applied to investigate, for the first time, the possibility of activating the inert basal surfaces of 2H‐MoTe 2 monolayers by N‐ or P‐doping for overall electrocatalytic water splitting. The results show that both N‐ and P‐doping significantly change the surface charge distribution and electronic band structure of 2H‐MoTe 2 . In addition, the doping‐induced structural disorder generates more active sites, leading to improved electrochemical activities for both hydrogen and oxygen evolution reactions (HER and OER). Especially, N‐doped 2H‐MoTe 2 (4 × 4 × 1) exhibits a better OER catalytic performance with a small overpotential of 1.82 eV (vs normal hydrogen electrode), while both N‐ and P‐doped MoTe 2 monolayers exhibit outstanding HER catalytic performance with a Gibbs free energy of the hydrogen adsorption ( for N‐doped MoTe 2 and for P‐doped MoTe 2 ) smaller than that of pristine 2H‐MoTe 2 (). The study provides an effective strategy for regulating the electroactivity of layered transition metal dichalcogenides for enhanced overall water splitting.
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