Latest ArticlesExploring highly efficient electrocatalysts and understanding the reaction mechanisms for hydrogen electrocatalysis, including hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) in alkaline media are conducive to the conversion of hydrogen energy. Herein, we reported a new strategy to boost the HER/HOR performances of ruthenium (Ru) nanoparticles through nitrogen (N) modification. The obtained N-Ru/C exhibit remarkable catalytic performance, with normalized HOR exchange current density and mass activity of 0.56 mA/cm2 and 0.54 mA/µg, respectively, about 4 and 4.5 times higher than those of Ru/C, and even twofold enhancement compared to commercial Pt/C. Moreover, at the overpotential of 50 mV, the normalized HER current density of N-Ru/C is 5.5 times higher than that of Ru/C. Experimental and density functional theory (DFT) results verify the electronic regulation of Ru after N incorporation, resulting in the optimized hydrogen adsorption Gibbs free energy (ΔGH*) and hence enhancing the HOR/HER performance.
A novel copper-based MOFs adsorbent (Cu-BTC-Th) was prepared using an one-step method by introducing a new organic ligand of 4-thioureidobenzoicacid (Th) with active groups for selectively adsorbing Pb(Ⅱ) from aqueous solutions. The chemical composition and structure of the prepared MOFs materials were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Brunner−Emmet−Teller (BET) analysis, and zeta potential measurements. The adsorption capability of the prepared Cu-MOFs was significantly enhanced by introducing the new organic ligand of Th in the materials. The maximum adsorption capacity of the Cu-BTC-Th for Pb(Ⅱ) attains 732.86 mg/g under the optimal conditions. In addition, the adsorption kinetics and adsorption isotherm analysis showed that the adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption model, indicating that the adsorption of Pb(Ⅱ) by Cu-BTC-Th was a monolayer chemisorption. The adsorption mechanism of Cu-BTC-Th for Pb(Ⅱ) was discussed and revealed. On one hand, the adsorption of Pb(Ⅱ) is mainly through ion exchange with the Cu(Ⅱ). On the other hand, the −NH2 and −C=S functional groups introduced in the Cu-BTC-Th materials have stronger coordination ability with the Pb(Ⅱ) ions to enhance the adsorption capability.
Photoelectrochemical (PEC) sensor is an emerging technology in analysis as the advantage of fast response, high sensitivity and uncomplicated operation. In this study, an effective label-free PEC sensor for bisphenol A (BPA) detecting is constructed, in which ZnIn2S4/g-C3N4 heterojunction is prepared via a simple hydrothermal method. The characterization outcomes display that the formation of p-n heterojunction helps for promoting the separation efficiency of photo-generated carrier. Under visible light irradiation, the ZnIn2S4/g-C3N4 modified electrode exhibits broader liner range from 0.05 mmol/L to 30 mmol/L and lower detection limit of 0.016 µmol/L (S/N = 3) with remarkable stability and reproducibility of detection BPA under visible light irradiation. Furthermore, the constructed PEC sensor displays favorable potential for detection of BPA in practical applications.
The electrocatalytic methanol conversion is of importance in direct methanol fuel cell, biomass reforming, and hydrogen generation. To achieve a "carbon-neutral" target, CO2 byproducts derived from biofuels should be mitigated. In contrast to the complete oxidation of methanol to CO2, the selective oxidation of methanol to formate is a CO2-emission-free route without the generation of toxic CO intermediates. Herein, we present a highly active catalyst based on transition-metal disulfide nanosheet arrays supported on Ni foam for methanol conversion. Through composition screening, we find that the FeCoNi disulfide nanosheet exhibits a highly efficient and selective methanol-to-formate conversion. The surface reconstruction of this catalyst allows us to produce 0.66 mmol cm−2 h−1 of formate at low potential (1.40 V) with high faradaic efficiency of > 98%. This work offers a substantial composition tuning strategy to construct noble-metal-free active multi-metal sites for CO2-emission-free conversion of methanol to value-added formate.
Anthrones are key structural motifs in many natural products, bioactive compounds and pharmaceutical chemicals. Earth-abundant-metal-catalyzed asymmetric functionalization of anthrones has not proved to be viable. Herein, we disclosed a highly enantioselective propargylic substitution of anthrones with propargylic esters using copper salts with chiral N, N, P-ligand. This strategy is amenable to a broad range of substrates, uses readily available starting materials, provides excellent yields with remarkable enantioselectivity under mild conditions, and enables attractive products diversification routes.
The biological activities of a series of 3, 3′-spirocyclic indole derivatives containing CF2, phosphine oxide, indole, and cyano functional groups were evaluated, and these derivatives were found to exhibit anti-TMV, fungicidal, and insecticidal activities.
Chiral covalent organic frameworks (CCOFs) featuring chirality, stability, and good porosity have attracted a considerable amount of attention due to their important applications, such as asymmetric catalysis, chiral separation, and chiral recognition. In this study, a β-cyclodextrin (β-CD) covalent organic framework (β-CD-COF) diluted with polysiloxane OV-1701 was explored as a novel chiral stationary phase (CSP) for gas chromatography (GC) separation of racemates. The β-CD-COF coated capillary column had excellent selectivity, not only for the separation of linear alkanes, linear alcohols, fatty acid methyl esters mixture, the Grob mixture and positional isomers, but also for the resolution of chiral compounds, including chiral alcohols, aldehydes, ethers, and amino acid derivatives. In addition, the β-CD-COF-coated capillary column presented good repeatability and reproducibility. This work indicated the great potential of the CCOFs coated capillary column for the chromatographic separation of enantiomers.
The selective synthesis of N2-sulfonyl and N2-H 1, 2, 3-triazoles via organocatalytic annulation of enaminone/enaminoester with sulfonyl azide has been realized. The unconventional selectivity providing N2-sulfoyl 1, 2, 3-triazoles takes place in pure water, wherein the hydrogen bond effect between water and the intermediate resulting from enamine-azide corporation accounts for the novel reaction selectivity. On the other hand, the reactions conducted in DMSO specifically afford N2-H 1, 2, 3-triazoles in the absence of such hydrogen bond effect.
Excellent radiation resistance is a prerequisite for pressure-sensitive hydrogels to be used in high-energy radiation environments. In this work, tannic acid-modified boron nitride nanosheet (BNNS-TA) is first prepared as the radiation-resistant additive by a facile one-step ball milling of hexagonal boron nitride and tannic acid. Then, polyacrylamide (PAAm)-based pressure-sensitive hydrogel doped with BNNS-TA and Fe3+ ions is fabricated. The ternary BNNS-TA/Fe3+/PAAm hydrogel exhibits excellent compressive strength (at least four times the compressive strength of unfilled pure PAAm hydrogel), pressure-sensitive performance (gauge factor is up to 1.4), and performance recovery due to the combination of multiple intermolecular interactions, such as covalent crosslinking, hydrogen bonds, and ion coordination interactions. The BNNS-TA/Fe3+/PAAm hydrogel can be made as a pressure sensor installed in the control circuit or attached on the human body to detect human activities accurately. More importantly, the compressive strength and the pressure-sensitive performance of the BNNS-TA/Fe3+/PAAm hydrogel can be maintained after the hydrogel is irradiated by 60Co gamma-ray at an absorbed dose of 15 kGy. As a comparison, the compressive strength of the unfilled PAAm hydrogel is only a quarter of that before irradiation. This work not only reveals a facile method to achieve the preparation of chemically modified BNNS as a promising radiation-resistant additive but also provides a novel strategy for the development of pressure-sensitive hydrogel devices in radiation environments.
The electro-Fenton process, with its capacity for in-situ H2O2 formation and Fe2+ regeneration, is a striking alternative to the traditional chemical-Fenton process. However, the frequent requirement of extra binders for electrode fabrication leads to low catalyst utilization, a complex fabrication process, and weak conductivity. Herein, a three-dimensional (3D) porous electrode was fabricated in-situ on a Ni foam (NF) substrate integrated with nitrogen-doped carbon nanotubes (N@C) derived from carbonization of zeolitic imidazolate framework-8 (ZIF-8) without any binder. The resulting 900/N@C-NF cathode (synthesized at 900 ℃) was high in surface area, N content, and degree of graphitization, achieved high performance of H2O2 production (2.58 mg L−1 h-1 H2O2/mg catalyst) at -0.7 V (vs. SCE), and enabled prompt regeneration of Fe2+. The electro-Fenton system equipped with the 900/N@C-NF cathode was effective in removing a diverse range of organic pollutants, including rhodamine B (RhB), phenol, bisphenol A (BPA), nitrobenzene (NB), and Cu-ethylenediaminetetraacetic acid (EDTA), and significantly attenuating the concentration of chemical oxygen demand (COD) in the real acid wastewater, exhibiting superior activity and stability. This binder-free and self-supporting electro-Fenton cathode was thus shown to be an attractive candidate for application to wastewater treatment, particularly those rich in organics, acids, and Fe3+/Fe2+.
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