Highly flexible, mesoporous structured, and metallic Cu-doped C/SiO2 nanofibrous membranes for efficient catalytic oxidative elimination of antibiotic pollutants

Perspectives Toward Damage-Tolerant Nanostructure Ceramics

Advanced ceramic materials and devices call for better reliability and damage tolerance. In addition to their strong bonding nature, there are examples demonstrating superior mechanical properties of nanostructure ceramics, such as damage-tolerant ceramic aerogels that can withstand high deformation without cracking and local plasticity in dense nanocrystalline ceramics. The recent progresses shall be reviewed in this perspective article. Three topics including highly elastic nano-fibrous ceramic aerogels, load-bearing nanoceramics with improved mechanical properties, and implementing machine learning-assisted simulations toolbox in understanding the relationship among structure, deformation mechanisms, and microstructure-properties shall be discussed. It is hoped that the perspectives present here can help the discovery, synthesis, and processing of future structural ceramic materials that are insensitive to processing flaws and local damages in service.

Improvement strategies for oil/water separation based on electrospun SiO2 nanofibers

Oil spills and oily effluents from industry and daily life pose a great threat to all organisms in the ecosystem, while aggravating the problem of water scarcity, which has developed into a global challenge. Therefore, the development of advanced materials and technologies for oil/water separation has become a focus of attention. One-dimensional (1D) SiO2 nanofibers (SNFs) have become one of the most widely used inorganic nanomaterials in the past due to their stable chemical properties, excellent biocompatibility, and high temperature resistance etc. Meanwhile, electrospinning technique, as an emerging technology for treating oil/water emulsions, electrospun SNFs on this basis also has a number of advantages such as adjustable wettability, diverse structure and good connectivity. This review provides a systematic overview of the research progress of electrospun SNFs in different aspects. In this review, we first introduce the basic principles of electrospun SNFs, then focus on the design structures of various SNFs, propose corresponding strategies for the property improvement of SNFs, also analyze and consider the applications of SNFs. Finally, the challenges faced by electrospun SNFs in the field of oil/water separation are analyzed, and the future directions of electrospun SNFs are summarized and prospected.

Construction of Mo-Based p-n Heterojunction with Enhanced Oxidase-Mimic Activity for AOPs and Antibiofouling

Advanced oxidation processes (AOPs) are efficient methods to remove poisonous organic pollutants from water. But in AOPs, additional radical providers, such as H2O2, persulfate, and permonosulfate, are indispensable, which not only add the risk of secondary pollution but also increase cost and complexity in operation. To resolve this problem, nanozymes with oxidase-mimic activity are a prospective choice, which can convert O2 in the air to ·OH and degrade organic pollutants. Here, CoMoO4/MoS2, a nanozyme with excellent oxidase-mimic activity, is synthesized. In the structure, the p-n heterojunction generates between p-type CoMoO4 and n-type MoS2. Energy band analysis and theoretical calculations suggest the p-n heterojunction intensifies adsorption toward O2, which improves oxidase-mimic activity. This facilitates the generation of ·OH and improves organic pollutant degradation performance with AOPs. Furthermore, CoMoO4/MoS2 also exhibits an antibiofouling ability due to the existence of ·OH. This work clarifies the connection between the structure and oxidase-mimic activity for nanozymes with the p-n heterojunction. More importantly, a new AOP without additional radical providers is developed based on oxidase-mimic activity.

Synthesis of Cu Nanoparticles Incorporated Mesoporous C/SiO2 for Efficient Tetracycline Degradation

In this study, a Cu NPs-incorporated carbon-containing mesoporous SiO2 (Cu/C-SiO2) was successfully synthesized through a grinding-assisted self-infiltration method followed by an in situ reduction process. The obtained Cu/C-SiO2 was then employed as a Fenton-like catalyst to remove tetracycline (TC) from aqueous solutions. TEM, EDS, XRD, N2 adsorption-desorption, FTIR, and XPS methods were used to characterize the crystal structure, morphology, porosity, chemical composition, and surface chemical properties of the catalyst. The effects of initial TC concentration, catalyst dosage, H2O2 dosage, solution pH, HA addition, and water media on the TC degradation over Cu/C-SiO2 were investigated. Scavenging and electrochemical experiments were then carried out to analyze the TC degradation mechanism. The results show that the Cu/C-SiO2 can remove 99.9% of the concentrated TC solution (C0 = 500 mg·L-1), and it can be used in a wide pH range (R.E. = 94-99%, pH = 3.0-11.0). Moreover, hydroxyl radicals (•OH) were detected to be the dominant reactive species in this catalytic system. This study provides a simple and promising method for the synthesis of heteroatom-containing mesoporous catalysts for the decomposition of antibiotics in wastewater.

One stone, two birds: A Cu-S cluster as a laccase-mimicking nanozyme and sulfite activator for phenol remediation in marine environments

Phenols are infamous pollutants in marine environments and present a grave danger to human health, which makes their efficient detection and removal serious issues. Colorimetry is a simple method for detecting phenols in water because phenols can be oxidized by natural laccase and generate a brown product. However, high cost and poor stability impede the wide-spread implementation of natural laccase in phenol detection. To reverse this adverse situation, a nanoscale Cu-S cluster, Cu₄(MPPM)₄ (Cu₄S₄, MPPM = 2-mercapto-5-n-propylpyrimidine), is synthesized. As a stable and inexpensive nanozyme, Cu₄S₄ shows excellent laccase-mimicking activity and prompts the oxidation of phenols. This characteristic makes Cu₄S₄ a perfect option for phenol detection with colorimetry. In addition, Cu₄S₄ also exhibits sulfite activation properties. It can degrade phenols and other pollutants with advanced oxidation processes (AOPs). Theoretical calculations show good laccase-mimicking and sulfite activation properties originating from appropriate interactions between Cu₄S₄ and substrates. We anticipate that the phenol detection and degradation characteristics of Cu₄S₄ make it a promising material to be used for practical phenol remediation in water environments.

Enhanced Visible-Photocatalytic Activities in Strong Acids and Strong Alkalis of Flexible Iron-SrTiO3 Nanofibrous Membranes

Traditional SrTiO₃ (STO) materials have high brittleness and poor deformation resistance. In this work, macroscopically flexible iron-doped SrTiO₃ (SFTO) nanofibrous membranes were prepared by electrospinning and calcination, which can be easily isolated and can maintain integrity to recycle as photocatalysts. Moreover, the SFTO nanofibrous membranes showed enhanced photocatalytic performance under strong acids (pH = 2) and strong alkalis (pH = 12). The SFTO nanofibrous membranes increased the catalytic rate of Congo red (CR) dye by about 10 times in visible light. The mechanism of photocatalytic activity enhancement was discussed by the combined effects of hydroxyl radicals and superoxide radicals. The successful preparation of SFTO nanofibrous membranes has offered a simple and economical approach to photocatalysis as well as environmental remediation.

Guest Molecule Insertion-Optimized d-Band Center Position in MoS2 with Improved Sulfite Activation Ability Inspired by Sulfite Oxidase

As a prospective member in the family of advanced oxidation processes (AOPs), heterogeneous sulfite activation shows low cost and high safety for poisonous organic pollutants' degradation. To obtain an efficient sulfite activator, sulfite oxidase (SuO_x), a molybdenum-based enzyme that can prompt oxidation and activation of sulfite, inspired us greatly. Based on the structure of SuO_x, MoS₂/BPE (BPE = 1, 2-bis-(4-pyridyl)-ethylene) is synthesized successfully. In MoS₂/BPE, the BPE molecule is inserted between the MoS₂ layers as a pillar and the N atom links with Mo⁴⁺ directly. MoS₂/BPE shows excellent SuO_x mimic activity. Theoretical calculation implies that BPE insertion optimizes the d-band center position of MoS₂/BPE, which regulates the interaction between MoS₂ and *SO₄^2-. This prompts ^•SO₄^- generation and organic pollutants' degradation. At pH 7.0, its tetracycline degradation efficiency achieved is 93.9% in 30 min. Furthermore, its sulfite activation ability also endows MoS₂/BPE with excellent antibiofouling performance because ^•SO₄^- can kill the microorganisms in water effectively. This work develops a new sulfite activator based on SuO_x. The connection between structure and SuO_x mimic activity and sulfite activation ability is clarified in detail.

Enhancing mechanical and photocatalytic properties by surface microstructure regulation of TiO2 nanofiber membranes

In this work, TiO₂ nanofiber membrane (NFM) with a complete surface microstructure was prepared through regulating the surface microstructure of TiO₂ NFM by doping Zr. The crystal structures and morphological analyses indicated that the nanofiber membranes were consisted by disordered accumulation of Zr-doped TiO₂ nanofibers with a crack-free surface, small grain size and high aspect ratio. When the doping amount of Zr was 0.8 mL, the tensile strength of the doped membranes reached 1.27 MPa, which was 60.7% higher than that of pure TiO₂ NFM. The photocatalytic performance of Zr-doped TiO₂ NFM was evaluated by the degradation performance of Methylene orange (MO) under simulated sunlight irradiation. Compared with the undoped TiO₂ NFM, the 0.8-Zr/TiO₂ NFM presented a higher catalytic degradation efficiency (improved by 69.6%), and the photocatalytic performance maintained stable after five circulating. It was found that the doping of Zr ions effectively limited the surface crack size and grain size of TiO₂ nanofibers, thereby improving the tensile strength, and enhanced the surface area effect and carrier transfer efficiency of TiO₂ NFM. On the other hand, a narrow band-gap was obtained by doping a small amount of Zr ions, which expanded the visible light response range to improve the photocatalytic performance of TiO₂ nanofibers.

From 1D Nanofibers to 3D Nanofibrous Aerogels: A Marvellous Evolution of Electrospun SiO2 Nanofibers for Emerging Applications

One-dimensional (1D) SiO₂ nanofibers (SNFs), one of the most popular inorganic nanomaterials, have aroused widespread attention because of their excellent chemical stability, as well as unique optical and thermal characteristics. Electrospinning is a straightforward and versatile method to prepare 1D SNFs with programmable structures, manageable dimensions, and modifiable properties, which hold great potential in many cutting-edge applications including aerospace, nanodevice, and energy. In this review, substantial advances in the structural design, controllable synthesis, and multifunctional applications of electrospun SNFs are highlighted. We begin with a brief introduction to the fundamental principles, available raw materials, and typical apparatus of electrospun SNFs. We then discuss the strategies for preparing SNFs with diverse structures in detail, especially stressing the newly emerging three-dimensional SiO₂ nanofibrous aerogels. We continue with focus on major breakthroughs about brittleness-to-flexibility transition of SNFs and the means to achieve their mechanical reinforcement. In addition, we showcase recent applications enabled by electrospun SNFs, with particular emphasis on physical protection, health care and water treatment. In the end, we summarize this review and provide some perspectives on the future development direction of electrospun SNFs.

Sub-Nanoporous Engineered Fibrous Aerogel Molecular Sieves with Nanogating Channels for Reversible Molecular Separation

Gating molecular separation using artificial sub-nanoporous molecular sieves is highly desirable in large-scale chemical and energy processing, such as gas separation, hydrogen recovery, carbon dioxide capture, seawater desalination, etc. However, it has remained an insurmountable challenge to create such materials. Herein, a binary meso-reconstruction strategy to develop biomimetic sub-nanoporous engineered aerogel molecular sieves (NAMSs) with reversible nanogating channels is demonstrated, in which sub-1 nm pores (≈7 Å) provide coupling size-thermodynamic gated functions that enable molecule discrimination and trapping in a reversible manner. The NAMSs show polarity-reversible adsorption in which adsorbate molecules are discriminated by each gate-admission sponge-fiber molecular sieve, facilitating size/interface synergistically induced selective separation of 1,3,5-trimethyl benzene/ethylene glycol with high separation factor and fast adsorption rate. The nanogating aerogel molecular sieves with molecularly defined sub-1 nm nanoporous architecture (≈7 Å), Murray's law hierarchical channels, ultrahigh surface area (686 m² g^-1 ), and robust self-supporting characteristics define a new benchmark for both aerogels and molecular sieves, exhibiting great potential in diversified on-demand molecular separations that are prevalent in chemical, energy, and environmental processes.

SO3 decomposition over silica-modified β-SiC supported CuFe2O4 catalyst: characterization, performance, and atomistic insights

The sulfur-iodine (S-I) thermochemical water-splitting cycle is one of the potential ways to produce hydrogen on a large scale. CuFe₂O₄ was dispersed over modified silica or treated β-SiC and untreated β-SiC using the wet impregnation method for SO₃ decomposition, which is the most endothermic reaction of the S-I cycle. Various state-of-the-art techniques such as XRD, FT-IR, BET, XPS, TEM, HR-TEM, FESEM-EDS and elemental mapping were employed to characterize both the synthesized catalysts. CuFe₂O₄ catalyst supported on silica-modified β-SiC resulted in enhanced catalytic activity and stability due to better metal-support interaction. In order to get a better insight into the reaction mechanism over this bimetallic catalyst, the first principles based simulation under the framework of density functional theory was performed. We have found that the presence of Cu gives rise to an improved charge localization at the O-vacancy site alongside favourable reaction kinetics, which results in an enhanced catalytic activity for the CuFe₂O₄ nano-cluster compared to that of a single metallic catalyst containing Fe₂O₃ nano-cluster.

Highly sensitive formaldehyde sensors based on CuO/ZnO composite nanofibrous mats using porous cellulose acetate fibers as templates

An innovative formaldehyde sensor based on CuO/ZnO composite nanofibrous mats (C-NFMs) coated quartz crystal microbalance (QCM), which is capable of stable determination of formaldehyde gas at ambient temperatures sensitively and selectively, has been successfully fabricated. Triaxial and highly porous C-NFMs with high surface area (126.53 m² g^-1) were synthesized by electrospinning a sol-gel cellulose acetate (CA)/CuAc₂/ZnAc₂ complex solution and following by calcination process. Benefiting from the unique heterojunction structure, immense pore interconnectivity and large surface area of C-NFMs, the as-developed QCM sensors exhibited an extremely low limit of detection (LOD) down to 26 ppb and a limit of quantification value equals to 87 ppb. Besides, the C-NFMs coated QCM sensors also demonstrated short response times (80s), the long-term stability during 3 weeks as well as good selectivity to formaldehyde over diverse volatile organic compounds. The sorption equilibrium in the adsorption process of QCM coated sensors was well met with the Freundlich model, which certified the heterogeneous adsorption between formaldehyde gas and C-NFMs.

Fire-Resistant and Hierarchically Structured Elastic Ceramic Nanofibrous Aerogels for Efficient Low-Frequency Noise Reduction

Traffic noise has been regarded as one of the most annoying pollutions that induce severe hazards to human health, both physiological and psychological. The commonly used fibrous noise absorption materials are limited by their large density, poor sound absorption ability at low frequencies, and unsatisfactory fire-resistant ability. Here, we develop hierarchically structured elastic ceramic electrospun nanofibrous aerogels, which possess lightweight properties (density of 13.29 mg cm^-3) and superior low-frequency sound absorption ability (NRC value of 0.59). Specifically, the obtained ceramic electrospun nanofibrous aerogel is nonflammable on exposure to fire and can be compressed and quickly recover to its original height without any visible damage. Moreover, the resultant aerogels could be facilely and efficiently manufactured into designed shapes on a large scale, demonstrating their potential for industrialization. The successful design of such ceramic-based bulk materials may provide new insights for the further development of the next-generation high-efficiency sound-absorbing products.

A novel composite membrane for simultaneous separation and catalytic degradation of oil/water emulsion with high performance

It is of great significance to develop novel membranes with dual-function of simultaneously separating oil/water emulsion and degrading the contained water-miscible toxic organic components. To meet this requirement, a dual-functional Ni nanoparticles (NPs)@Ag/C-carbon nanotubes (CNTs) composite membrane was fabricated via electroless nickel plating strategy in this study. The as-prepared composite membrane possessed superhydrophilicity with water contact angle of 0° and splendid underwater oleophobic property with oil contact angle of 142°. When the membrane was applied for separation of surfactant stabilized oil-in-water emulsion, high permeate flux (about 97 L m^-2·h^-1 under gravity), oil rejection (about 98.8%) and antifouling property were achieved. Benefitting from the NiNPs@Ag/C-CNTs layer on membrane surface, the composite membrane exhibited high catalytic degradation activity for water-miscible toxic organic pollutant (4-nitrophenol) with addition of NaBH₄ in a flow-through mode. Meanwhile, the NiNPs@Ag/C-CNTs composite membrane possessed excellent durability, which was verified by the good structural integrity even under ultrasonic treatment. The cost-efficiency, high separation and degradation performance of the prepared membrane suggested its great potential for treatment of oily wastewater.

A novel co-catalyzed system between persulfate and chlorite by sonolysis for removing triphenylmethane derivative

Triphenylmethane (tpm) derivatives (e.g. tpm_CV) have threatened the safety of the aquatic environment due to the potential toxicity and carcinogenicity. In this study, the novel ultrasonic/persulfate/chlorite (US/S₂O₈^2-/ClO₂^-) oxidation process was developed for the effective removal of tpm_CV in wastewater. The apparent non-integer kinetics (n around 1.20) of tpm_CV degradation under different factors (R²_Adj > 0.990) were investigated, respectively. Inhibiting effects of anions were greater than those of cations (except Fe(II/III)). The adding of micromolecule organic acids could regulate degradation towards positive direction. The double response surface methodology (RSM) was designed to optimize tpm_CV removal process, and the acoustic-piezoelectric interaction was simulated to determine the propagation process of acoustic wave in the reactor. The possible degradation pathway was explored to mainly include carbonylation, carboxylation, and demethylation. The estimated effective-mean temperature at the bubble-water interface was calculated from 721 to 566 K after introducing the ClO₂^-, however, the adsorption or partitioning capacity of tpm_CV in the reactive zone was widened from 0.0218 to 0.0982. The proposed co-catalysis of US/S₂O₈^2-/ClO₂^- was based on the determined active species mainly including ClO₂, SO₄⋅^-, and ⋅OH. Compared with other US-based processes, the operating cost (3.97 $/m³) of US/S₂O₈^2-/ClO₂^- with the EE/O value (16.8 kWh/m³) was relatively reduced.

An electrochemical sensor based on electrospun MoS2@SnO2 modified carbon nanofiber composite materials for simultaneously detection ofphenacetin and indomethacin

SnO 2 -CNF was prepared by coaxial blending technology, and MoS 2 was grown uniformly on SnO 2 -CNF composite by combining hydrothermal post-treatment step. The uniform distribution of MoS 2 on one-dimensional SnO 2 -CNF can effectively establish a layered three-dimensional structure. So that the prepared MoS 2 coated SnO 2 -CNF composite material has higher surface area and more active sites to obtain better electrochemical performance. We constructed an electrochemical sensor within the composite material with enhanced performance to realize the simultaneous and highly sensitive detection of phenacetin and indomethacin for the first time. The sensor proves the linear ranges of 0.050-7200 μM and 0.05-500 μM respectively, and the detection limits were 0.016 μM and 0.013 μM. And the sensor has good anti-interference ability and stability, which also achieves good recovery rate in the actual sample detection .

A phase transition-induced photocathodic p-CuFeO2 nanocolumnar film by reactive ballistic deposition

Vertical nanocolumnar Cu–Fe–O electrodes synthesized by the reactive ballistic deposition technique followed by heat treatment in an Ar atmosphere undergo a switch for conductivity at elevated temperatures.

One stone two birds: a sinter-resistant TiO2 nanofiber-based unbroken mat enables PM capture and in situ elimination

Airborne particulate matter (PM) primarily resulting from fossil fuel burning is an increasingly global issue. In this work, an intrinsically fragile TiO₂ nanofibrous mat was facilely engineered with good structural integrity, flexibility, foldability, and high-temperature resistance (~1300 °C), by suppressing the sintering (i.e., growth) of nanocrystallites in each single nanofiber. Such functionalization enables self-regenerative air filtration for PM capture and in situ catalytic elimination in a "one-stone-two-birds" approach. Finite element analysis simulation revealed the retained nanopores in each anti-sintering nanofiber could facilitate the air flow during filtration. Without any chemical or physical modification, this self-standing and lightweight (7.1 g m^-2) fibrous mat showed 96.05% filtration efficiency for 3-5 μm NaCl particles, with a low pressure drop of only 18 Pa and high quality factor of 0.179 Pa^-1 under an airflow velocity of 32 L min^-1. By utilizing its photocatalytic attribute, the nanofibrous mat in situ eliminated the captured particles from incense burning under one Sun irradiation in 4 h, and thereby spontaneously regenerated in an easy manner. The straightforward grafting of Au nanoparticles onto nanofibers could enable a quick degradation toward cigarette smoke, mainly due to the photothermally elevated local temperature by Au around the reactive sites. The plasmonic fibrous mat kept a high and stable filtration efficiency of PM_0.3, PM_2.5, and PM₁₀ over 98.62%, 99.76%, and 99.99% during an outdoor long-term filtration test for 12 h under sunlight irradiation (Nanjing, China, September, 26^th, 2020, 7:30 to 19:30). This work provides a solution for solving the airborne pollution from its source, prolonging the lifetime of the filter, and avoiding the risk of producing secondary pollution.

Flexible Stannum-Doped SrTiO3 Nanofiber Membranes for Highly Sensitive and Reliable Piezoresistive Pressure Sensors

Mechanically flexible ceramic fiber-based electronic skins are attractive materials ascribed to the features of monitoring signals of various physical parameters in a harsh environment, but the inherent brittleness of the ceramic fibers has limited their wide applications in emerging fields, such as fire-protecting clothing. Herein, a strategy to fabricate the flexible stannum(IV)-doped SrTiO3 (SSTO) nanofiber membranes by a facile sol-gel electrospinning method is reported. The calcination temperature and Sn4+ doping content play vital roles in regulating the crystalline and pore structures that are closely relevant to the flexibility and mechanical properties of the resultant SSTO nanofiber membranes. The as-prepared SSTO nanofiber membranes exhibited exceptional flexibility with an optimum tensile strength of 0.22 MPa, an elongation rate of 1.8%, and a Young's modulus of 13.3 MPa. Significantly, the flexible SSTO nanofiber-based piezoresistive sensors exhibited intriguing sensing performance toward pressure involving high sensitivity (2.24 kPa-1) in a low-pressure range (<400 Pa), fast response time (12 ms) and recovery time (32 ms), good durability (>1000 cycles), and excellent stability at different humidity levels and elevated temperatures. Furthermore, the sensor can also accurately monitor the signals of human motion such as finger bending, throat swallowing, and radial pulse. The fabrication of flexible ceramic nanofiber-based piezoresistive sensors would pave the way to fabricate wearable devices for fire-protecting clothing, personal healthcare, real-time human activity detection.

Flexible zirconium doped strontium titanate nanofibrous membranes with enhanced visible-light photocatalytic performance and antibacterial activities

Constructing flexible perovskite structured ceramic fibrous materials would potentially facilitate applications of photocatalysis, wearable devices, and energy storage. However, current perovskite structured ceramic fibrous materials were fragile with small deformation resistance, which have limited their wide applications. Herein, flexible zirconium doped strontium titanate (ZSTO) nanofibrous membranes were fabricated via combining sol-gel and electrospinning methods. The microstructures (pore and crystal) of ZSTO nanofibers were affected by zirconium doping contents and closely relevant to flexibility of resultant membranes. The probable mechanism for flexibility of ZSTO nanofibrous membranes was presented. Furthermore, the silver phosphate modified ZSTO (AZSTO) exhibited superior photocatalytic performance towards tetracycline hydrochloride (TCHC) and antibacterial performance towards Gram-negative and Gram-positive bacteria with visible-light irradiation, including 85% degradation towards TCHC within 60 min, >99.99% inhibition rate and > 3 mm inhibition zone against Gram bacteria. Furthermore, the·superoxide free radical (O₂^-) and holes played significant roles in the degradation of TCHC that verified by radical scavenger experiment. Additionally, the membranes exhibited good reusability over five cycles without tedious recycling operations needed for micro/nanoparticle-based catalysts. The successful fabrication of ZSTO nanofibrous membranes would provide a new insight into photocatalysts, antibacterial materials, and wearable device.

Charged membranes based on spider silk-inspired nanofibers for comprehensive and continuous purification of wastewater

Creating a facile and efficient porous membrane for the comprehensive treatment of both insoluble and soluble pollutants from water is of great significance, yet remains challenging. Here, we present a facile strategy to prepare charged nanofibrous membranes assembled from spider silk-like humped SiO₂/polyamide 66 (PA66)/polyaniline (PANI) nanofibers by combing Plateau-Rayleigh instability-induced assembly andin situsynthesis. The obtained nanofibrous membranes possess micro/nanostructured surfaces with promising superhydrophilic and underwater superoleophobic property, which are attributed to the synergy of hierarchical roughness and hydrophilic matrix. Combined with the superwettability and the integrated property of submicron pore size, high porosity, and good pore interconnectivity, the membranes can separate various oil-in-water emulsions with a remarkable permeation flux of 5403 l m^-2h^-1and a high separation efficiency (total organic carbon content <5 mg l^-1). Moreover, attributed to the Laplace pressure difference and positive potential of the spindle-knotted nanofibers, the biomimetic nanofibrous membranes could remove the filter cake during separation. In addition, the membrane exhibits a remarkable adsorption-reduction capacity of hexavalent chromium. The synthesis of such attractive nanomaterials may provide new insights into the development of multifunctional separation materials for environmental applications.

Comparing dark- and photo-Fenton-like degradation of emerging pollutant over photo-switchable Bi2WO6/CuFe2O4: Investigation on dominant reactive oxidation species

The extensive use of tetracycline hydrochloride (TCH) poses a threat to human health and the aquatic environment. Here, magnetic p-n Bi₂WO₆/CuFe₂O₄ catalyst was fabricated to efficiently remove TCH. The obtained Bi₂WO₆/CuFe₂O₄ exhibited 92.1% TCH degradation efficiency and 50.7% and 35.1% mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system, respectively. The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II) and Cu(II)/Cu(I) conversion for the Fenton-like reaction between Fe(II)/Cu(I) and H₂O₂, thereby generating abundant •OH for pollutant oxidation. Various environmental factors including H₂O₂ concentration, initial pH, catalyst dosage, TCH concentration and inorganic ions were explored. The reactive oxidation species (ROS) quenching results and electron spin resonance (ESR) spectra confirmed that •O₂^- and •OH were responsible for the dark and photo-Fenton-like systems, respectively. The degradation mechanisms and pathways of TCH were proposed, and the toxicity of products was evaluated. This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation.

Oxygen vacancy-mediated sandwich-structural TiO2-x /ultrathin g-C3N4/TiO2-x direct Z-scheme heterojunction visible-light-driven photocatalyst for efficient removal of high toxic tetracycline antibiotics

A surface defect sandwich-structural TiO_2-x/ultrathin g-C₃N₄/TiO_2-x direct Z-scheme heterojunction photocatalyst is successfully constructed. The results manifest the existence of oxygen vacancies, sandwich structure and direct Z-scheme heterojunction. Noticeably, TiO_2-x/ultrathin g-C₃N₄/TiO_2-x efficiently eliminates high toxic tetracycline hydrochloride by means of·O₂^-, h⁺ and·OH, whose removal rate is 87.7% during 90 min and the pseudo-first-order rate constant reaches up to 31.7 min^-1 × 10^-3. The extraordinary performance can be attributed to the special 3D structure, Z-scheme heterojunction expediting charge transfer and promoting the generation of active species, meanwhile the oxygen vacancies enhancing the spatial separation of photo-induced carriers. Moreover, various environmental factors are systematically explored by statistics. SO₄^2-, NH₃-N and pH exhibit an obvious impact on removal rate. Meanwhile, TiO_2-x/ultrathin g-C₃N₄/TiO_2-x could also effectually remove tetracycline hydrochloride from complex actual-wastewater and exhibit high stability. Besides, the photocatalytic mechanism and degradation path of tetracycline hydrochloride are also elucidated.

Facile Construction of a Copper-Containing Covalent Bond for Peroxymonosulfate Activation: Efficient Redox Behavior of Copper Species via Electron Transfer Regulation

Heterogeneous catalysis can be enhanced through the construction of effective atom connection for rapid electron transport on the catalyst surface. Hence, this study proposed a new strategy for electron transfer regulation to facilitate redox cycle of Cu(II)/Cu(I). The objective was achieved by successful construction of copper-containing covalent bond through the in situ growth of porous g-C₃N₄ with oxygen dopants and nitrogen defects (O-CN_D) on CuAl_xO_y substrate (CuAl@O-CN_D). On the basis of X-ray absorption fine structure (XAFS) and other characterization results, the facilitated redox behavior of copper species by electron transfer regulation was ascribed to the formation of a C-O-Cu bond on the porous-rich superficial of the catalyst; these covalent C-O-Cu bonds shortened the migration distance of electrons between Cu(II) and Cu(I) via Cu(I)-O-C-O-Cu(II) bridge. The construction of copper-containing covalent bonds in the catalyst resulted in efficient PMS activation for a rapid redox cycle of Cu(II)/Cu(I), triggering a series of reactions involving the continuous production of three highly active species (SO₄^·-, ^·OH and ¹O₂). The rapid diffusion and transportation of the generated active species from porous structures directly attack typical pharmaceutically active compounds (PhACs), achieving superior catalytic performance. This study provides a new routine to construct a C-O-Cu bond for PMS activation by regulating the electron transfer to accelerate the redox behavior of copper species for environmental remediation.