Junfeng Geng

Heterogeneous photo-electro-Fenton (HPEF) reaction is a highly efficient process using H2O2 produced by in-situ two electron oxygen reduction reaction (2e ORR) after aerating for the elimination of refractory organic pollutants. Herein, an effective MOFs derived Fe/C/N @ ZIF-8 @ACF composite electrode for HPEF was prepared by loading Fe/C/N derived from Fe-based metal-organic frameworks (Fe-MOFs) and zeolitic imidazolate framework-8 (ZIF-8) on activated carbon felt (ACF). By supplying air, solar light, and low external electric current (32 mA·cm−2) to the cathode, ZIF-8 could generate H2O2 by 2e- ORR process, and Fe/C/N could react with H2O2 to form strong oxidative radicals (·OH). Photocatalysis accelerates the Fenton reaction greatly with the abundant photo-generated electrons. The HPEF activity of different systems for the degradation of antibiotics was compared. The results showed that the degradation rate of antibiotics can be greatly increased with the best of ∼100% within 100 min. Moreover, the electrode could still maintain a high activity after reuse for 4 times, which proved to be highly active, stable, and well recyclable for a rapid HPEF oxidation for abatement of antibiotic pollutants in water. •A novel Fe/C/N @ ZIF-8 @ACF composite electrode has been prepared by hydrothermal synthesis.•H2O2 can be produced in-situ through the ORR catalysis of ZIF-8 then to be catalytic decomposed into·OH by Fe/C/N.•The Fe/C/N @ ZIF-8 @ACF showed enhanced adsorption and photoelectro-Fenton performance.•It provides a new method for the field of water treatment to treat waste water with fast, green and economic methods.

Synergy of photocatalytic hollow nanospherical anatase {001}-N-TiO2, Fe3O4-incorporated adsorptive vine-shaped carbon fiber and was constructed for efficient pollutant capturing, photodegradation and catalyst recovery, potentially applicable for water decontamination. [Display omitted] •Triple-functional catalyst exhibits high photocatalytic efficiency and reusability.•The composite exhibited enhanced activity under visible light irradiation.•The synergy between spot light and photocatalysis has been demonstrated.•The composite catalysts have superior durability and recycled with magnetic property. Developing highly performance TiO2-based photocatalyst for pollutant removal from environmental media is of increasing interest from both research and practical perspectives. However, there are currently few developed materials effective for fully addressing all limitations in the catalytic performance and real application. Herein, we report the fabrication of triple-functional {001}-N-TiO2/VSCF/Fe3O4 through a one-step hydrothermal-template synthesis coupled with composite methods as an effective material towards resolving most of the dilemmas. The resultant composite incorporated efficient pollutant capture and photocatalytic degradation, material recovery into one individual, which consists of a hollow-spherical {001}-N-TiO2 photocatalytic site, a vine-shaped carbon fiber adsorptive loader and a Fe3O4 magnetic-responsive part. When exposed to the pollutant under light irradiation, the {001}-N-TiO2/VSCF composite showed remarkable photocatalytic performance. The magnetic-responsive property of {001}-N-TiO2/VSCF/Fe3O4 facilitated catalyst recovery, the composite exhibited good catalytic stability during recycling uses. Our triple composite {001}-N-TiO2/VSCF/Fe3O4 may be applied as a comprehensive functional, efficient and recyclable material for eliminating the current problems in environmental remediation and purification.

A dielectrophoresis (DEP) method for direct capture and fast removal of Anabaena was established in this work. The factors affecting the removal efficiency of Anabaena were investigated systematically, leading to optimized experimental conditions and improved DEP process equipment. The experimental results showed that our improved DEP method could directly capture Anabaena in eutrophic water with much enhanced removal efficiency of Anabaena from high-concentration algal bloom-eutrophication-simulated solution. The removal rate could increase by more than 20% after applying DEP at 15 V compared with a pure filtration process. Moreover, the removal rate could increase from 38.76% to 80.18% in optimized experimental conditions (the initial concentration of 615 μg/L, a flow rate of 0.168 L/h, an AC voltage of 15 V, and frequency of 100 kHz). Optical microscopic images showed that the structure of the captured algae cells was intact, indicating that the DEP method could avoid the secondary pollution caused by the addition of reagents and the release of phycotoxins, providing a new practical method for emergent treatment of water bloom outbreaks.

[Display omitted] •Pd nanoparticles dispersed in carbon black were further loaded on carbon felt (Pd/C@CF) can catalyze the production of atomic hydrogen (H*).•H* can replace the Fe2+ to reduce H2O2 in a Fenton-like reaction with H2O as byproduct.•The effects of various influence factors on the electro-Fenton process induced by H* reactivity were investigated.•The Pd/C@CF cathode was proved to be a little pH dependent, highly stable, and potentially practical applications in wastewater treatment. Heterogeneous electro-Fenton (HEF) reaction is a highly efficient process for the degradation and mineralization of refractory organic pollutants in water. Since atomic hydrogen H*, currently widely used in electrocatalytic hydrogen dechlorination (ECHD) domains, can rapidly transfer one electron to H2O2 to generate OH and H2O, it has been considered as a promising species instead of Fe2+ for HEF reactions. However, H* is extremely unstable as it can be easily combined into hydrogen gas (H2), appropriate electro-catalytic material would be needed in order to speed up the production of H* on the one hand, and stabilize this in-situ formed species on the other. Here we show that house-synthesized Pd nanoparticles dispersed in carbon black (∼8 % Pd on carbon) which were further loaded on carbon felt (Pd/C@CF) exhibited an excellent performance in HEF process for degradation of a variety of organic compounds (with the best of ∼99 % in 75 min). Radical scavenging experiments revealed that hydroxyl radical (OH) was the key reactive species, and cyclic voltammetry tests proved the stabilization of H* by Pd nanoparticles which in turn resulted in a significant increase in the yield of OH via the reduction of H2O2. The superior performance could be attributed to the Pd nanoparticles dispersed uniformly in carbon with a large number of active sites, thereby lowering the over potential to create a suitable microenvironment for H* generation and stabilization. In addition, the Pd/C@CF composite was proved to be a little pH dependent, highly stable, and well recyclable for effective utilization of H* towards a rapid HEF oxidation for potentially many practical applications in wastewater treatment.

Working on a dielectrophoresis experimental system assembled in our laboratory, we find that the bacteria, Escherichia coli, can be efficiently removed from drinking water by the system. Synthetic water samples of 300 mL of E. coli were treated for 20 min at a flow rate of 1 L/h. The removal efficiency reaches 95.24% high at the voltage of 6 V, and 100% at 15 V. As the technique is featured by its simplicity and low cost for water treatment, it promises a rapid, affordable, and industry-scale removal of E. coli and other similar pathogenic microorganisms from drinking water.

The removal of excessive amounts of nitrate and phosphate from water sources, especially agricultural wastewater, has been of high significance to control eutrophication in aquatic systems. Here, a new method is reported for the removal of nitrate and phosphate simultaneously from wastewater based on the combination of the solution-phased adsorption (ADS) and dielectrophoresis (DEP) techniques. The plant ash was first selected as the adsorbent by screening tests, followed by a systematic investigation of using the adsorbent to remove nitrate and phosphate from wastewater under various experimental conditions, including the testing of adsorbent dosage, pretreatment time, water flow rate, and electrode voltage. The analysis of the adsorbent particles was also performed by scanning electron microscope (SEM) analysis, the energy dispersive X-ray spectroscopy (EDX) test, and the measurement of Zeta potentials. Compared with the ADS method alone, the introduction of DEP into the purification process has greatly increased the removal rate by 66.06% for nitrate and 43.04% for phosphate, respectively. In the meantime, it is observed that the processing time has been greatly reduced by 92% with the assistance of DEP.

A novel solid–liquid two-phase precipitation (SLTPP) method, utilising a solidified (via liquid N2) m-xylene solution of C60 with liquid isopropanol (IPA) as a counter-solvent, is proposed for the synthesis of fullerene (C60) nanowires. The resulting C60 nanowires were observed to possess high crystallinity and a length-to-diameter ratio of up to several thousands with a diameter as small as ∼85 nm. We further systematically investigated the effects of the C60 concentration (1–5.2 mg ml−1) and solvent–counter-solvent ratio (1 : 6–2 : 1) to optimise the growth conditions for high-quality, size-controlled C60 nanowires. A comparative study on the widely-used liquid–liquid interfacial precipitation (LLIP) method showed that the proposed SLTPP method led to a much narrower diameter distribution (414.20 ± 92.10 nm vs. 3237.20 ± 1790.30 nm for LLIP) across the studied range of the C60 concentrations and solvent–counter-solvent ratios, and is therefore considered to be a more stable and reliable synthesis route. We propose that the gradual melting of the m-xylene C60 solid-phase leads to slower diffusion of the solvent–counter-solvent medium, providing a much more stable interface for high-quality crystal growth.

Fullerene (C-60) nanowires have attracted significant attention in the past two decades due to their outstanding chemical and physical properties, which render the material a wide range of potential applications. Much effort has been devoted to exploring the growth methods, structural and compositional characterizations, and application-related investigations of this novel carbon nanomaterial. Here, we present a review of C-60 nanowires in which we will first describe the recent development in the material preparations, analytical techniques, crystal structures, chemical compositions, and the investigations of polymerization processes. Afterward, we will discuss the mechanistic studies on the nanowires' growth as the mechanism research is of great importance for their size control, large-scale preparation, and for the exploration of applications in a wide range of fields. Finally, we will discuss the potential applications in several directions, including optical, electrical, mechanical, and biological fields, as well as our perspectives to future developments.

[Display omitted] •One-step synthesis of photocatalyst with LaNiO3/TiO2 structure.•The existence of S-scheme heterostructure was supported by active species experiment.•The samples exhibit excellent photocatalytic performance. LaNiO3/TiO2 step-like composite heterojunction photocatalysts were synthesized via a facial in-situ sol‐gel method with different calcination temperatures. The crystal structure and performance of synthetic photocatalyst are characterized by X‐ray diffraction (XRD), transmission electron microscope (TEM), UV‐vis absorption spectroscopy and X-ray photoelectron spectroscopic spectroscopy (XPS). The results illustrate that binary structure of LaNiO3/TiO2 step-scheme heterojunction can be obtained at a calcination temperature of 700 °C, and it extends light‐absorption to the visible region. Moreover, the LaNiO3/TiO2 shows superior photocatalytic efficiency with respect to methyl orange (MO) degradation under visible light irradiation for 75 min, the degradation rate in MO solution of 10 mg/L and 20 mg/L are respectively 2 times and 3 times higher than pure LaNiO3. The synthetic photocatalyst also performed effective photocatalytic ability of antibiotic ciprofloxacin under visible light, and the degradation efficiency is higher than pure TiO2 and LaNiO3. Enhancement of organic degradation activity can be attributed to improvement of the electron-hole pairs separation rate caused by the formation of S-scheme heterostructure.

An economical and green synthetic method is reported for preparing N-doped TiO2 nanoparticles modified with carbon (denoted as C@N–TiO2) by abandoning additional carbon sources in the synthetic process but utilizing the carbon element contained in precursors. Full characterizations including XRD, TEM, Raman spectra, XPS, TG, FTIR, BET, CV, and LSV are performed to determine the composition, structure, morphology, optical and electronic properties of C@N–TiO2. Methyl orange (MO), methylene blue (MB), and phenol are selected as photodegrading agent to evaluate the photocatalytic activity of the as-prepared product. Our results show that C@N–TiO2 displays superior dye-adsorption ability and photocatalytic activity under visible light than pure TiO2. In addition, C@N–TiO2 exhibits much enhanced electrochemical properties, with a nine-fold improvement of photocurrent intensity as compared with pure TiO2. •C@N–TiO2 composites are successfully synthesized via an in-situ approach.•The composite displays enhanced photocatalytic degradation under visible light irradiation.•The composite exhibits a nine-fold improvement of photocurrent intensity than TiO2.•C@N–TiO2 displays superior adsorption ability.