Solar‐driven reduction of CO2, which converts inexhaustible solar energy into value‐added fuels, has been recognized as a promising sustainable energy conversion technology. However, the overall ...conversion efficiency is significantly limited by the inefficient charge separation and sluggish interfacial reaction dynamics, which resulted from a lack of sufficient active sites. Herein, Bi12O17Cl2 superfine nanotubes with a bilayer thickness of the tube wall are designed to achieve structural distortion for the creation of surface oxygen defects, thus accelerating the carrier migration and facilitating CO2 activation. Without cocatalyst and sacrificing reagent, Bi12O17Cl2 nanotubes deliver high selectivity CO evolution rate of 48.6 μmol g−1 h−1 in water (16.8 times than of bulk Bi12O17Cl2), while maintaining stability even after 12 h of testing. This paves the way to design efficient photocatalysts with collaborative optimizing charge separation and CO2 activation towards CO2 photoreduction.
Defect‐rich Bi12O17Cl2 superfine nanotubes were prepared for the photocatalytic reduction of CO2. Benefiting from the superfine nanotube structure to accelerate charge separation and oxygen defects to facilitate CO2 activation, the Bi12O17Cl2 nanotubes displayed a CO formation rate of 48.6 μmol g−1 h−1 in water without cocatalyst and sacrificial reagent, which is roughly 16.8 times that of bulk Bi12O17Cl2.
Magnetic nanostructured MnFe
2
O
4
with different morphologies, synthesized via chemical co-precipitation and hydrothermal method, was assayed as heterogeneous Fenton catalysts. The as-prepared MnFe
...2
O
4
catalysts were thoroughly characterized by various characterization methods, such as X-ray diffraction (XRD), N
2
adsorption-desorption, transmission electron microscopy (TEM), magnetic hysteresis loops, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic activity of MnFe
2
O
4
catalysts was evaluated in the heterogeneous Fenton degradation of ofloxacin (OFX). In our study, the morphology exhibited a critical impact on the catalytic activity of MnFe
2
O
4
. For example, MnFe
2
O
4
nanorods (MnFe
2
O
4
-NR) had a higher catalytic activity than MnFe
2
O
4
nanospheres (MnFe
2
O
4
-NS) and MnFe
2
O
4
nanocubes (MnFe
2
O
4
-NC) in OFX removal and H
2
O
2
decomposition. Notably, the catalytic activity was remarkably enhanced with increasing the relative amount of Mn
3+
and Fe
2+
species on the surface. Based on the results from quenching experiments and quantitative determination of •OH radicals, a possible catalytic mechanism of MnFe
2
O
4
was proposed. In addition, the stability and reusability of MnFe
2
O
4
-NR was ascertained, as the results suggested that MnFe
2
O
4
-NR was a stable and easily separated catalyst for heterogeneous Fenton process.
A CuCl-catalyzed Ullmann-type C–N cross-coupling reaction of carbazoles and 2-bromopyridine derivatives has been developed for the synthesis of N-heteroarylcarbazole derivatives employing ...1-methyl-imidazole and t-BuOLi as ligand and base, respectively, both of which are found to significantly promote the reaction. Low cost and low loading of both catalyst and ligand, together with high reaction yields, render this practical reaction to be suitable for large-scale preparations and could be useful in material science.
In this study, the decomposition of methanol into the CO and H species on the Pd/tungsten carbide (WC)(0001) surface is systematically investigated using periodic density functional theory (DFT) ...calculations. The possible reaction pathways and intermediates are determined. The results reveal that saturated molecules, i.e., methanol and formaldehyde, adsorb weakly on the Pd/WC(0001) surface. Both CO and H prefer three-fold sites, with adsorption energies of – 1.51 and – 2.67 eV, respectively. On the other hand, CH
3
O stably binds at three-fold and bridge sites, with an adsorption energy of – 2.58 eV. However, most of the other intermediates tend to adsorb to the surface with the carbon and oxygen atoms in their sp
3
and hydroxyl-like configurations, respectively. Hence, the C atom of CH
2
OH preferentially attaches to the top sites, CHOH and CH
2
O adsorb at the bridge sites, while COH and CHO occupy the three-fold sites. The DFT calculations indicate that the rupture of the initial C-H bond promotes the decomposition of CH
3
OH and CH
2
OH, whereas in the case of CHOH, O-H bond scission is favored over the C-H bond rupture. Thus, the most probable methanol decomposition pathway on the Pd/WC (0001) surface is CH
3
OH → CH
2
OH →
trans
-CHOH → CHO → CO. The present study demonstrates that the synergistic effect of WC (as carrier) and Pd (as catalyst) alters the CH
3
OH decomposition pathway and reduces the noble metal utilization.
•Catalytic activity of co-catalysts is found to be closely related to the polarity.•High selectivity of products in the cyclohexane oxidation is achieved.•We report a new approach for preparing ...glutaric acid.
Several polar molecules, such as alcohols, ketones, esters and acids, were used as co-catalysts for the cyclohexane oxidation catalyzed by manganese porphyrins, and the catalytic activity was found to be closely related to polarity of co-catalysts. The results indicated that the total selectivity of products was as high as 96.3% and glutaric acid selectivity was up to 50.9%. Thus, the proposed method provides a new approach for preparing glutaric acid.
•A new on-off-on fluorescent assay for detecting chiral amino acids was developed.•Chiral nano ZnTPyP was synthesized for chiral recognition of amino acids.•The assay method was reliable and robust ...with high selectivity and sensitivity.•It realized accurate detection of amino acids in biological environment.
Interests in the recognition of chiral amino acids have grown tremendously in recent years, particularly in the fields of food analysis and pharmaceutical studies. Herein, an innovative “on-off-on” fluorescent assay has been developed for the sensitive and selective determination of chiral Proline (Pro), Lysine (Lys), and Serine (Ser). This detection platform is constructed by exploiting the fluorescence quenching ability of chiral self-assembly zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (ZnTPyP) to CdTe quantum dots (CdTe QDs). CdTe QDs can act as signal switches whose fluorescence signals can effectively quenched by chiral nano ZnTPyP and then restored in the presence of enantiomer amino acids. The coupling use of CdTe QDs and chiral nano ZnTPyP also permits quantitative analysis of d-Pro, d-Lys, l-Ser with detection limits of 4.46 × 10−10 mol L−1, 7.13 × 10−11 mol L−1, and 3.35 × 10−11 mol L−1, respectively. The approach is also suitable for the effective detection of the three amino acids in complex biological matrices. This rapid, robust and reliable strategy for recognizing enantiomer amino acids has not been reported. The proposed method can be a powerful and valuable technology in the areas of drug discovery and food chemistry.
Effects of chelating agents on the catalytic degradation of bisphenol A (BPA) was studied in the presence of BiFeO3 nanoparticles as a heterogeneous catalyst and H2O2 as a green oxidant. The ...oxidizing ability of H2O2 in the presence of nano-BiFeO3 alone was not so strong to degrade BPA at neutral pH values, due to the limited catalytic ability of nano-BiFeO3. Once the surface of nano-BiFeO3 was in situ modified by adding proper organic ligands, the BPA degradation was much accelerated in the pH range of 5–9. The enhancing effect of the ligand was observed to have an order of blank < tartaric acid < formic acid < glycine < nitrilotriacetic acid < ethylenediaminetetraacetic acid (EDTA). The addition of 0.25 mmol L–1 EDTA in the H2O2–BiFeO3 system at pH 5.0 and 30 °C increased the BPA removal from 20.4% to 91.2% with reaction time of 120 min. The enhancing effect of the ligand was found to be indifferent of the possible dissolution of iron from nano-BiFeO3, but correlated well with the accelerated •OH formation from the H2O2 decomposition at the BiFeO3 surface, which was confirmed by ESR measurements and density functional theory studies. In general, more addition of EDTA, higher H2O2 concentrations, or higher temperatures were favorable to the BPA degradation. The effect of the EDTA addition on the kinetics of BPA degradation was also clarified.
A facile and elegant method for synthesis of novel N–aryl phenothiazine derivatives from 2-phenylindolizines and phenothiazines through direct electrochemical oxidation has been developed. This ...approach was performed smoothly at room temperature without external oxidant and catalyst. Cyclic voltammetry and in situ FTIR techniques were applied to analyze the cross-coupling process of phenothiazines and 2-phenylindolizines, which helped to select the appropriate reaction potential. Under the optimized conditions, a broad range of substrates were well tolerated, affording the desired products in moderate to excellent isolated yields (up to 91%) with high regioselectivity. Meanwhile, a plausible mechanism involving a radical pathway has been proposed.
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A facile and efficient direct electrochemical oxidation method for C–H/N–H cross-coupling of 2-phenylindolizines with phenothiazines to synthesize novel N-aryl phenothiazine derivatives has been developed. Under the optimized conditions, a broad range of substrates were well tolerated, affording the desired products in moderate to excellent isolated yields (up to 91%) with high regioselectivity.
A sulfonic acid functionalized metal–organic framework (MOF) Cr3(μ3-O)(H2O)3(NDC(SO3H5/6)2)3 (BUT-8(Cr)-SO3H, NDC(SO3H)2 2– = 4,8-disulfonaphthalene-2,6-dicarboxylatlate) with high chemical and ...thermal stability is used for the catalytic esterification, showing excellent performance in various esterification reactions of monoacids, diacids, and acid anhydrides. In the structure of this MOF, uniformly distributed catalytic active sites of Brønsted acidic −SO3H with high density are decorated on its one-dimensional channels, which leads to improved catalytic activity. The reaction conversion and corresponding yield of esters can achieve >99% and >90%, respectively. BUT-8(Cr)-SO3H also represents good size-selectivity in the catalytic esterification owning to the steric or impeded diffusion effects of reactants in its pore structure. In addition, its robust structure also guarantees good reusability. On the basis of the above advantages and excellent catalytic performance, this acid group functionalized MOF could be a promising candidate for the sustainable chemical catalysis.
