Search

Organic contamination of water results in significant risks to the biosphere and human health. The treatment of organic pollutants found in effluents urgently requires a green, sustainable, and effective approach. Herein, a straightforward one-step procedure was developed to create a photocatalytic mesh using iron mesh as the substrate and the g-C3N4/MIL-101(Fe) heterostructure as the photocatalytic material to activate persulfate (PS) for the removal of methyl orange (MO) from water. Fluorescence stereo microscopy (FSM), scanning electron microscopy (SEM), nitrogen adsorption–desorption, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffraction (XRD) were used to characterize the morphological and physicochemical properties of the synthesized composites, which confirmed the successful growth of g-C3N4/MIL-101(Fe) on the iron mesh. The outstanding PS activation capacity of g-C3N4/MIL-101(Fe) promoted electron transfer and accelerated the generation of SO4˙−, resulting in up to 91.05% MO degradation under 60 min of visible light exposure. The removal mechanisms were investigated by quenching experiments and electron spin resonance (ESR), which proved that ˙OH, ˙O2− and h+ contributed to the removal of MO. Moreover, the degradation pathways of MO and the as-formed intermediates were identified by high-resolution mass spectroscopy (HRMS). This study provides a convenient and economical method to build innovative photocatalytic systems for organic pollutant degradation. [ABSTRACT FROM AUTHOR]

Efficient activation of hydrogen peroxide (H2O2) through biomimetic catalysis still faces a major challenge. In this work, inspired by the catalytic pocket of natural peroxidase, Cu single atom (CuSA) and AuCu nanoparticles (AuCuNPs) anchored on nitrogen‐doped carbon skeleton (CuSA‐AuCuNPs/NC) serve as dual active sites that significantly accelerate the charge transfer process and thus achieve efficient H2O2 activation. Meanwhile, the experimental and theoretical calculations show that the well‐established electronic communication effect between CuSA and AuCuNPs results in moderate electronic modifications to CuSA, which promotes the heterolysis of H2O2 and the timely desorption of H2O. As a proof of concept, CuSA‐AuCuNPs/NC show remarkable performance in detecting uranyl ions in seawater. This work provides new insights into the H2O2 activation for colorimetric sensing. [ABSTRACT FROM AUTHOR]

ZnO quantum dots (QDs) supported on porous nitrogen-doped carbon (ZnOQDs/P-NC) exhibited excellent electrochemical performance for the electroreduction of CO2 to CO with a faradaic efficiency of 95.3% and a current density of 21.6 mA cm−2 at −2.2 V vs. Ag/Ag+. [ABSTRACT FROM AUTHOR]

A rapid and highly selective naked-eye detection of hydrochloric acid (HCl) in an aqueous medium was established using HCl-triggered redispersion of gold nanoparticle aggregates. [ABSTRACT FROM AUTHOR]

The triazine‐based covalent organic frameworks (tCOF), an intriguing subtype of COFs, are expected as highly promising photocatalysts for various photocatalytic applications owing to their fully conjugated structures and nitrogen‐rich skeletons. However, the inherent hydrophobicity and fast recombination of photoexcited electron‐hole pairs are two main factors hindering the application of tCOF in practical photocatalytic reactions. Here, a post‐synthetic modification strategy to fabricate superhydrophilic tCOF‐based photocatalysts is demonstrated by in situ growing FeOOH clusters on TaTz COF (TaTz‐FeOOH) for efficient photocatalytic oxidation of various organic pollutants. The strong polar FeOOH endows TaTz‐FeOOH with good hydrophilic properties. The well‐defined heterogeneous interface between FeOOH and TaTz allows the photoelectrons generated by TaTz to be consumed by Fe (III) to transform into Fe (II), synergistically promoting the separation of holes and the generation of free radicals. Compared with the unmodified TaTz, the optimized TaTz‐FeOOH (1%) shows excellent photocatalytic performance, where the photocatalytic degrade rate (k) of rhodamine B is increased by about 12 times, and the degradation rate is maintained at 99% after 5 cycles, thus achieving efficient removal of quinolone antibiotics from water. This study provides a new avenue for the development of COF‐based hydrophilic functional materials for a wide range of practical applications. [ABSTRACT FROM AUTHOR]

The rapid advancement of science and technology has led to the development of electronic devices that require higher energy storage capacities. Because of their greater energy as well as power density capabilities, hybrid supercapacitors offer an answer to the problems that result from the limitations of both supercapacitors and batteries when it comes to power densities and energy density. Borate ion-functionalized nickel manganese hydroxide nanoparticles (denoted as NiMnB) were prepared by a simple chemical reduction method, and novel complexes were obtained by growing NiMnB with a core-shell structure on reduced graphene oxide (rGO). The NiMnB inner core facilitates electron transport, while the borate/metal borate shell layer on the outer layer aids in OH- absorption. Additionally, rGO integrates the dispersed nanoparticles, resulting in a comprehensive conductive system. This design optimizes the electrochemical performance of NiMn-based electrodes. The specific capacitance of the NiMnB/rGO-16 electrode was 916 F g−1 when tested at a current density of 1 A g−1. NiMnB/rGO-16 was used as the positive electrode and activated carbon (AC) as the negative electrode assembled the hybrid supercapacitor. It showed strong cycling stability and an energy density of 50.2 Wh kg−1. [Display omitted] • Electrode materials with core-shell morphology (NiMnB/rGO) were successfully prepared by chemical reduction method. • NiMnB/rGO-16 electrode shows high specific capacitance of 916 Fg−1 at a current density of 1 A g−1. • The NiMnB/rGO-16//AC device exhibits a high energy density of 800.4 Wkg−1,50.2 Wh kg−1. • NiMnB/rGO-16//AC maintains 86.3 % of initial capacitance after 8000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

• A metal-free graphitized carbon nitride (g-C 3 N 4) nanosheets was synthesized by gas template method. • The surface area and photocurrent of nanosheets was 6 and 3 times than that of bulk g-C 3 N 4 , respectively. • The nanosheets showed superior photodegradation ability towards cefixime. • 99% of cefixime could be removed within 30 min under the sunlight and persulfate addition. The removal and the treatment of antibiotics in environmental water by advanced oxidation process (AOP) has attracted much attention. In this paper, a metal-free graphitized carbon nitride nanosheets (g-C 3 N 4 -NS) was synthesized by gas template method. Cefixime in water was removed by direct photocatalysis and activation of persulfate (PS) under simulated sunlight. The flaky morphology made g-C 3 N 4 -NS's band gap narrow, charge separation enhanced, light absorption enhanced, and more active sites were exposed. The specific surface area of g-C 3 N 4 -NS was about 6 times than that of bulk g-C 3 N 4 , and its photocurrent was about 3 times. The effects of different PS concentrations and pH values on photocatalytic activation in two ways were studied. The influence of anions on the removal of cefixime was also studied. The synthesized g-C 3 N 4 -NS has good stability, and its performance is well maintained after continuous photocatalysis and photoactivation catalysis. The degradation rate of cefixime by g-C 3 N 4 -NS was three times than that of bulk g-C 3 N 4 , and the removal rate of cefixime by g-C 3 N 4 -NS /PS system was 30 times than that of PS. This work provides advanced idea for metal-free AOP in environmental chemistry. [ABSTRACT FROM AUTHOR]

Schematic diagram for efficiently removal of Pb (Ⅱ) based on UiO-67-Rhodanine-3-acetic acid (Rd) composites. [Display omitted] • A new UiO-67-Rhodanine-3-acetic Acid(Rd) composites was synthesized successfully. • The composites exhibited superfast removal efficiencies for Pb (II) with huge adsorption capacities of 309.8 mg g−1. • The proposed method provided a new, effective and straightforward method for rapid and superior trapping Pb (II). • The removal of Pb (II) by UiO-67-AC-Rd as advanced sorbents was presented and further provided a new pathway to application for wastewater. Metal organic frameworks (MOFs) have the advantages of large specific surface area, high porosity, controlled structures and strong stability, and were excellent adsorbents for the efficient trapping of heavy metals. In this work, two morphologies of Zr-MOF composites (UiO-67-AC-Rd and UiO-67-FA-Rd) under different solvent conditions were synthesized by a sequential solvothermal process. The properties of the composites were characterized by SEM, TEM, XRD, XPS, and BET, and the adsorption capacities of Pb (II) were investigated in detail. The excellent performance of UiO-67-AC-Rd exhibited superfast removal efficiencies for Pb (II), ascribing to its surface contains plentiful oxygen, nitrogen and sulfur functional groups and large specific surface area, which makes it have fascinating properties in removing Pb (II), and the maximum adsorption capacity of Pb (II) was 309.8 mg g−1. Chelation and electrostatic adsorption were considered as the main adsorption mechanisms. Adsorption isotherms were fitted well using the Langmuir and Freundlich model, and the adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous. The UiO-67-AC-Rd composites maintained excellent adsorption capacity for Pb (II) after four consecutive cycles, and the removal efficiency was above 74 %. The study will further provide a new pathway to the application of UiO-67-Rd composites in the adsorption of heavy metals in wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as SPME fiber coating. • BTCH-PTA-COF processes large specific surface area, good chemical and thermal stability. • The BTCH-PTA-COF fiber has perfect extraction efficiency for PAHs. • The adsorption mechanism was confirmed by the density functional theory (DFT) calculation. In this study, a durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as fiber coating, which was applied to solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The hydrophobic and π-π packing interactions between BTCH-PTA-COF and PAHs were confirmed by contact angle experiments and Van der Waals surface electrostatic potential analysis. Further, large specific surface area, good chemical and thermal stability have positive promoting effect on extraction. The method of wide linearity (0.25–300 µ g·L−1), low detection limits (0.03–0.05 µ g·L−1) and high enrichment factors (767–1411) for the detection of PAHs is explored, coupling BTCH-PTA-COF based SPME with gas chromatography with hydrogen flame detector (GC-FID). The relative standard deviations (RSDs) for inter-day and intra-day extractions of PAHs are ranging from 4.1 % to 9.6 % and 2.9 % to 6.4 %, respectively. The method successfully detected and quantified trace PAHs in tea beverages and river water samples with recoveries from 88.5 % to 104.8 %. The BTCH-PTA-COF coated fiber is ultra-stable in recycled extraction and reused at least 120 times, which could surpass published and commercial SPME fiber. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different functional groups modifying WO 3 /R-MOFs (R = NH 2 , C 5 H 11 , C 5 F 11) were designed. • Hydrophobic WO 3 /C 5 F 11 -MOF improves oxygen mass transfer. • The formation of electron-deficient region in WO 3 /C 5 F 11 -MOF prolongs the relaxation time of electrons. The solar-driven photocatalytic degradation of persistent organic pollutants is considered as a promising water treatment approach. Nevertheless, the activity of photocatalytic degradation of pollutants is still limited by the rapid carrier recombination and sluggish oxygen mass transfer. Herein, we designed different functional groups modified WO 3 /R-MOF (MOF: MIL-125-Ti, R = NH 2 , C 5 H 11 , C 5 F 11) heterojunction to overcome the aforementioned limitations. Among them, WO 3 /C 5 F 11 -MOF exhibited an excellent degradation efficiency of 91.6 % for 4-chlorophenol pollutants, which was seven and two times higher than that of WO 3 /NH 2 -MOF and WO 3 /C 5 H 11 -MOF, respectively. The WO 3 /C 5 H 11 -MOF and WO 3 /C 5 F 11 -MOF exhibited hydrophobic and formed microscopic triphase interface, which increased oxygen transfer. Furthermore, strong electron-withdrawing property of fluorine in the C 5 F 11 - ligand generated electron-deficient regions, increasing the transfer rate of photo-generated electrons and prolonging the relaxation time of electrons. Thus, hydrophobic WO 3 /C 5 F 11 -MOF not only regulates the catalytic interface microenvironment, but also effectively inhibits the recombination of photo-generated carrier. This study provides an efficient strategy to achieve excellent photocatalytic activity via interfacial engineering. [ABSTRACT FROM AUTHOR]

• An innovative MOFs@COFs-based molecular trap materials were successfully prepared. • The hierarchical core–shell composite was used as solid-phase microextraction (SPME) fiber coating. • The possible adsorption mechanism was systematically verified and explained. • The proposed method provided a new, effective and low-cost method for rapid and superior capture PAHs. In view of the serious carcinogenic, teratogenic and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs), which cause significant harm to human beings and the environment. Therefore, developing rapid adsorption and efficient analytical methods are research topic with practical significance. Herein, an innovative MOFs@COFs-based molecular trap materials were prepared with hierarchical porous core–shell structure and used as solid-phase microextraction (SPME) fiber coating, which combined with high performance liquid chromatography (HPLC) to achieve the efficient separation, capture, and detection for 7 PAHs in real samples. The possible adsorption mechanism was systematically verified and explained. Under the optimized conditions, the method developed in this experiment had a wide linear range (0.005–400 µg·L−1) with a good linear correlation coefficient (R2 > 0.9984), low detection limits (0.002–0.405 µg·L−1, S/N = 3) and low quantification limits (0.005–1.351 µg·L−1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.26–3.64% and 0.40–5.91%, respectively. Besides, the fiber showed higher enrichment capacity and extraction efficiency for PAHs compared to commercial SPME fibers and other material fibers, and exhibited excellent acid-base stability and reproducibility. This work provided a favorable synthetic pathway for the preparation of MOFs@COFs composites by layer-modified assembly synthesis strategy, showed excellent practical applicability as a SPME fiber coating combined with HPLC, and could be realized to provide technical support for future studies on the separation, adsorption, and analysis of PAHs in the petrochemical industrial zone of the Yellow River Basin. [ABSTRACT FROM AUTHOR]