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[Display omitted] • CA-Cu/TCN was fabricated by a citric acid (CA)-initiated self-assembly strategy. • CA induced the formation of tubular morphology, bridging C replacement, and N defects. • Ultra-dispersed CuN x sites and N vacancies resulted in excellent activity of CA-Cu/TCN. • Efficient degradation of ciprofloxacin (95.9 %) in CA-Cu/TCN photo-Fenton system. • Ciprofloxacin degradation was a gradual detoxification process for harmless disposal. The low utilization of visible light and easy recombination of charge carriers of graphitic carbon nitride (CN) restrain its application as photo-electron donor and metal site support in photo-Fenton system. Herein, a hydrogen bond-induced supramolecular self-assembly strategy was created to fabricate an ultra-dispersed Cu-loaded porous tubular CN composite (CA-Cu/TCN) by the hydrothermal–pyrolysis method with citric acid (CA) as initiator and chelating agent. CA-Cu/TCN with rich nitrogen vacancies (NVs) and abundant ultra-dispersed CuN x sites exhibited narrow bandgap, favorable visible light absorption capability, and high separation and transfer efficiency of charge carriers. CA-Cu/TCN effectively catalyzed the activation of H 2 O 2 for generating abundant reactive oxygen species under visible light irradiation, contributing to efficient degradation of ciprofloxacin (CIP) with removal rate of 95.9 % and kinetic rate constant of 0.0948 min−1. The superior catalytic activity of CA-Cu/TCN can be ascribed to the effective transport of photogenerated electrons, high specific surface area, atomically dispersed Cu species, and enriched surface NVs. The mechanism of photo-Fenton catalytic degradation of CIP and possible degradation pathways were proposed as the dominant role of 1O 2. Toxicity evaluation of CIP and intermediates indicated that the degradation of CIP was a gradual detoxification process. This work offers a novel self-assembly strategy to design and synthesize highly active and sustainable visible light-driven photo-Fenton catalysts for effectively degrading organic pollutants. [ABSTRACT FROM AUTHOR]

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[Display omitted] • The catalytic mechanism and material preparation based on the piezoelectric effect. • The application of the piezoelectric effect in wastewater purification is expounded. • The development of the piezoelectric effect-assisted water purification technology. • The challenges and prospects of the piezoelectric effect in wastewater purification. The demands of human life and industrial activities result in a significant influx of toxic contaminants into aquatic ecosystems. In particular, organic pollutants such as antibiotics and dye molecules, bacteria, and heavy metal ions are represented, posing a severe risk to the health and continued existence of living organisms. The method of removing pollutants from water bodies by utilizing the principle of the piezoelectric effect in combination with chemical catalytic processes is superior to other wastewater purification technologies because it can collect water energy, mechanical energy, etc. to achieve cleanliness and high removal efficiency. Herein, we briefly introduced the piezoelectric mechanisms and then reviewed the latest advances in the design and synthesis of piezoelectric materials, followed by a summary of applications based on the principle of piezoelectric effect to degrade pollutants in water for wastewater purification. Moreover, water purification technologies incorporating the piezoelectric effect, including piezoelectric effect-assisted membrane filtration, activation of persulfate, and battery electrocatalysis are elaborated. Finally, future challenges and research directions for the piezoelectric effect are proposed. [ABSTRACT FROM AUTHOR]

This paper reports a nanomixed valence FeWO 4 -coated 2D Ti 3 C 2 MXene (FW-MX) photocatalyst synthesised by a simple hydrothermal method. Ciprofloxacin, the main target pollutant, exhibited superior adsorption performance and high catalytic activity in the light-assisted Fenton system. In just 1 h, the removal rate of ciprofloxacin reached an impressive 76.89% using a minimal amount of FW-MX (10 mg). Meanwhile, the material exhibited good stability. Furthermore, the successful formation of mixed-valent FeWO 4 accelerated the rate-limiting step of Fe(III)/Fe(II) conversion, thereby enhancing the reactivity of the in situ photo-Fenton system. In the light-assisted Fenton system, FW-MX demonstrated greater potential compared to other common antibiotics, as FW-M100 exhibited superior photoreduction performance for heavy metal ions under the photo-Fenton oxidation system. This could further advance the practical application of AOPs technology in industrial wastewater treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Nano-photo catalysts have high efficiency, low energy consumption, no/low pollution, and are widely used in buildings dominated by cement-based materials, showing a good application prospect. The introduction of photo catalysts into cement-based materials can effectively improve their structural compactness, optimize their mechanical properties, endow them with the functions of pollutant degradation and surface self-cleaning, thus reducing the corrosion rate of cement-based materials and alleviating environmental pollution. This paper summarizes the different preparation methods of photocatalytic cement-based materials' introduces the influence of photo catalyst types on the photocatalytic properties of cement-based materials in detail, discusses the short¬comings of the current photocatalytic cement-based materials modified by nano-photocatalysts, and looks for¬ward to them future development direction. [ABSTRACT FROM AUTHOR]

Modified graphite felt is a widely studied cathode material at present. Because of its corrosion resistance, high specific surface area and low cost, it shows great potential in electrochemical oxidation reduction. In this paper, various modification methods of graphite felt, such as introduction of oxygencontaining functional groups, doping of hetero-atoms, deposition of carbon materials, hydrophobicity and so on, are reviewed, in addition, the application effect of modified graphite felt in the removal of organic pollutants in water environment was summarized. Finally, the future research hotspots and challenges were prospected. [ABSTRACT FROM AUTHOR]

Environmental context: With the rapid pace of industrialisation and urbanisation, soil contamination by organic pollutants has become a global focus of concern due to its serious threat to ecosystems and human health. Although a myriad of synthetic catalysts have been developed, natural minerals have the potential to be developed into cost-effective, environmentally benign and efficient catalysts to decontaminate soil. The efficient performance of natural minerals demonstrated in this study indicates a potential for their utilisation in the removal of refractory organic pollutants in soil. Rationale: Organic pollution of soil has raised worldwide concern owing to the potential effects on ecosystems and human health. Natural metal minerals rich in transition metal elements have the potential to be developed into environmentally benign activators of peroxymonosulfate (PMS) and hydrogen peroxide (H2O2) for soil decontamination. Methodology: A comparison study employing natural chalcopyrite (NCP) and natural pyrite (NP) as activators in the combined Fenton-like systems of PMS and H2O2 to degrade organic pollutants in soil has been carried out. Tetracycline hydrochloride (TCH) and phenanthrene (PHE) were selected as representatives of widely existing contaminants, antibiotics and polycyclic aromatic hydrocarbons, in the study. Key parameters including initial pH, catalyst and oxidants dosage were also optimised. Results: A total organic carbon (TOC) removal efficiency of 68.66% was achieved for TCH (500 mg kg–1) with the addition of 0.75 g L–1 NCP, 1.23 mM PMS and 1.23 mM H2O2 within 4 h, whereas a slightly lower mineralisation efficiency of 64.78% was obtained by the NP heterogeneous system. For PHE (50 mg kg–1), 93.04% of TOC was removed using a NCP/PMS/H2O2 process, which was much higher than that of NP (45.76%) after 24 h. The quenching experiments indicated that ˙OH prevailed over SO 4 ˙ − EN22116_IE1.gif , and ˙ O 2 − EN22116_IE2.gif also played a vital role in the PMS/H2O2 coupling process. Discussion: The more superior performance of NCP has been elucidated via X-ray photoelectron spectroscoy analysis and comparison of catalytic mechanisms. The existence of Cu+ played an important role in the transformation of Fe3+ to Fe2+ and facilitated the continuous generation of active radicals. A possible degradation pathway was proposed based on the intermediates identified by GC-MS analysis. We anticipate this study would provide implications for the utilisation of natural minerals in the removal of refractory organic pollutants in soil. Environmental context. With the rapid pace of industrialisation and urbanisation, soil contamination by organic pollutants has become a global focus of concern due to its serious threat to ecosystems and human health. Although a myriad of synthetic catalysts have been developed, natural minerals have the potential to be developed into cost-effective, environmentally benign and efficient catalysts to decontaminate soil. The efficient performance of natural minerals demonstrated in this study indicates a potential for their utilisation in the removal of refractory organic pollutants in soil. [ABSTRACT FROM AUTHOR]

The presence of organics in water poses a serious risk to the environment, as well as to human health. It is important to develop effective water treatment techniques that are affordable, durable, and sustainable. The removal and degradation of organic matter in water is widely explored using 2D and 3D nanomaterials, which are advantageous in providing high surface to volume ratios and favorably photoelectro activity as compared to traditional materials. The robustness of nano semiconductors has made it highly sustainable in water treatment. This review concentrates on nanostructured materials, which are demonstrating the removal of pollutants from water using various 2D and 3D nanostructured materials as photoelectrocatalytic electrodes. The 2D and 3D nanostructured materials are divided into five types according to physical morphology: nanofilms/nanosheets, nanopore structure/nanonetwork, nanoflowers, nanotubes, and other forms. Apart from this, the preparation method, characterization technology, and photoelectrocatalytic efficiency of organic pollutants degradation are reviewed. Finally, the different factors influencing degradation of organic pollutants are discussed. [ABSTRACT FROM AUTHOR]

Persulfate-based in situ chemical oxidation (ISCO) has been increasingly used for the remediation of contaminated groundwater and soil. In recent years, there have been numerous studies in the literature on all aspects of the activation of persulfate for contaminant removal at the laboratory scale, including the ways and mechanisms for the activation, the pathways of contaminant degradation, the factors associated with the activation performance, the methods characterizing the processes, etc. In contrast, studies in the literature on the practical use of the activated persulfate at the field scale are fewer, and at the same time have not been reviewed in an organized way. This review was initiated to summarize on the current research on the applications of activated persulfate for actual site remediation, and to extract the knowledge necessary for the formation of applicable technologies. The remediation efficiency and mechanism of activated persulfates by heat, alkaline, metal-based, and electrokinetic activated technologies are described. The major factors including pH, the persistence of persulfate, and the radius of influence and soil property during ISCO remediation applications were presented and discussed. Finally, the rebound process and impact towards microbial communities after in-situ chemical oxidation on site application were discussed. [ABSTRACT FROM AUTHOR]

Hydrodynamic cavitation (HC) technology with double parallel orifice plates can further enhance the degradation effect and heat generation efficiency and play an important role in practical large-scale organic wastewater treatment and energy saving. In this study, based on the optimal hole numbers in single orifice plate, the influences of the hole number and distribution in double parallel orifice plate on Basic Violet 1 (BV-1) degradation and heat generation are studied in detail. Furthermore, the effects of some experimental parameters (inlet pressure, initial concentration, solution temperature and solution volume) on BV-1 degradation and heat generation in 4 + 4 parallel orifice plate HC system are deeply studied. Then, the effect of added H 2 O 2 on the BV-1 degradation and heat generation is also investigated. In addition, the capturing experiments of free radicals (•OH and •O 2 -) are carried out. Finally, the BV-1 degradation pathway and possible degradation mechanism are proposed by analyzing the data of UV–vis spectrum, LC-MS and total organic carbon (TOC). The final results show that the solution temperature can be raised from 20.05 °C to 57.71 °C under the experimental conditions of 4 + 4 parallel orifice plates, 3.0 bar inlet pressure, 5.0 L total solution volume and 10 mg/L initial concentration for 90 min continuous circulation and the BV-1 degradation ratio can be achieved by 75.98 %. The system can generate 785.40 kJ heat at 48.50 USD/m3 cost and achieve 29.09 % thermal efficiency. For 1:30 molar ratio of BV-1 and H 2 O 2 , the solution temperature can be further raised to 63.32 °C in 90 min continuous cycling. 95.38 % BV-1 degradation ratio can be obtained and the 909.72 kJ heat can be generated, reaching the 33.69 % thermal efficiency. It is hoped that this work can provide a new strategy for enhancing the degradation of organic dyes and resource utilization of heat by using double parallel orifice plate HC technology. Hydrodynamic cavitation (HC) technology with double parallel orifice plates can further optimize the degradation effect and heat generation efficiency, which makes HC technology play an important role in practical large-scale organic wastewater treatment and energy saving. In this study, through studying the BV-1 degradation and heat generation in single orifice plate HC system, the orifice plate with the best effective number of holes is optimized and selected. Subsequently, based on the optimal hole numbers in single orifice plate, the influence of the hole numbers in double parallel orifice plate on BV-1 degradation and heat generation is studied in detail. Furthermore, the effects of different experimental parameters (inlet pressure, initial concentration, solution temperature and solution volume) on BV-1 degradation and heat generation in 4+4 parallel orifice plate HC system are deeply studied. Then, the effect of H 2 O 2 addition amount on the BV-1 degradation and heat generation in 4+4 parallel orifice plate HC system is investigated. In addition, the capturing experiment of free radicals (•OH and •O 2 -) are also carried out. Finally, the BV-1 degradation pathway and possible degradation mechanism are proposed by analyzing the data of UV-vis spectrum, LC-MS and total organic carbon (TOC). The final results show that the solution temperature can be raised from 20.05 °C to 57.71 °C under the experimental conditions of 4+4 parallel orifice plates, 3.0 bar inlet pressure, 5.0 L total solution volume and 10 mg/L initial concentration, and the BV-1 degradation ratio can be achieved by 75.98 % during 90 min continuous circulation. At the same time, the system can generate 785.40 kJ of heat at a cost of 48.50 USD/m3 and achieve a thermal efficiency of 29.09 %. Under the condition of BV-1: H 2 O 2 = 1:30, the solution temperature can be raised from 20.11 °C to 63.32 °C in 90 min continuous cycling, and the 95.38 % BV-1 degradation ratio can be obtained and the heat of 909.72 kJ can be generated, reaching the thermal efficiency of 33.69 %. This work provides a new effective strategy for enhancing the degradation of organic dyes and resource utilization of heat sources by orifice plate HC technology. It is hoped that the treatment method of printing and dyeing wastewater can lay a foundation for the further development of environmental protection and energy production. [Display omitted] [ABSTRACT FROM AUTHOR]

As a green and sustainable technology to relieve environmental pollution issues, semiconductor photocatalysis attracted great attention. However, most single-component semiconductors suffer from high carrier recombination rate and low reaction efficiency. Here, we constructed a novel visible-light-driven Z-scheme g-C3N4/AgBr-Ag photocatalyst (noted as CN-AA-0.05) using a hydrothermal method with KBr as the bromine source. The CN-AA-0.05 photocatalyst shows an excellent photocatalytic degradation performance, and a rhodamine B (RhB) degradation ratio of 96.3% in 40 min, and 2-mercaptobenzothiazole (MBT) degradation ratio of 99.2% in 18 min are achieved. Mechanistic studies show that the remarkable performance of CN-AA-0.05 is not only attributed to the enhanced light absorption caused by the Ag SPR effect, but also the efficient charge transfer and separation with Ag nanoparticles as the bridge. Our work provides a reference for the design and construction of efficient visible-light-responsive Z-scheme photocatalysts, and an in-depth understanding into the mechanism of Z-scheme photocatalysts. [ABSTRACT FROM AUTHOR]

Fenton reagent is known for over a hundred years and the role of homogeneous and heterogeneous Fenton degradation in wastewater treatment in removing recalcitrant organic contaminants is well appreciated and extensively explored. Limitations and shortcomings of homogeneous and heterogeneous Fenton degradation hinder the large-scale application of heterogeneous Fenton reactions in environmental remediation. Thus, the development of Fenton-like reagents is considered as a need of the hour. Most of the drawbacks of Fenton degradation have been taken care of by these novel reagents were dramatically increased catalytic degradation rate of contaminants was observed due to high surface area. Good mechanical stability, improved electron transfer, magnetically separability, and the possibility of widening the scope are the additional features of Fenton-like reagents. In this review, recent trends in the synthesis, strategies for enhancing its catalytic activity, and various applications of heterogeneous Fenton-like catalysts for the abatement of organic pollutants are discussed. This review describes the recent development of other transition metals, Graphene oxide/Carbon/CNT, MIL/MOF, and oxides as Fenton like catalysts in environmental remediation procedures even at ambient conditions. This review aims to encourage the fabrications of novel and efficient heterogeneous Fenton-like systems and assist the readers in the selection of the best suitable Fenton-like systems for industrial applications by unfolding the various properties and applications of these catalysts. [ABSTRACT FROM AUTHOR]

Visible light-driven photocatalysts have attracted considerable attention as these photocatalysts can effectively utilize visible light and are cost-effective. This study reports the synthesis of silver phosphate (Ag3PO4) and 1, 3, and 5% La, Zr co-doped Ag3PO4 via precipitation method. The synthesized materials were characterized using powder X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), UV-Visible diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). No impurities were observed in all the synthesized materials as shown by the XRD analysis. FTIR measurements of the synthesized materials displayed the presence of several functional groups in the synthesized materials. The band gap energy of Ag3PO4 decreases as more La and Zr were incorporated into the Ag3PO4 lattice. The SEM images of Ag3PO4 displayed tetrapod-shaped particles whereas La, Zr co-doped Ag3PO4 showed irregular particles. The photocatalytic activities of the synthesized materials were determined through photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes as well as photoreduction of Cr(VI). Results showed that 1% La, Zr co-doped Ag3PO4 exhibited superior photocatalytic properties in both photocatalytic processes when compared to Ag3PO4.

[Display omitted] • The electroprotic mechanism of H 2 O 2 activation on amorphous Nb 2 O 5 is described. • The factors affecting the activity of Nb 2 O 5 in organics degradation are discussed. • The changes in niobia properties after its interaction with H 2 O 2 are explained. • Recent advances in improving activity of Nb 2 O 5 are presented. • Future perspectives related to the development of Nb 2 O 5 -based catalysts are provided. Nowadays, niobium pentoxide (niobia) is attracting increasing interest as a promising component of heterogeneous catalysts addressed to oxidative degradation of organic pollutants. Particular attention is directed toward understanding the reactivity of this metal oxide in advanced oxidation processes (AOPs). To date, many authors have reported that Nb 2 O 5 is capable of degrading various organic molecules both upon exposure to UV light (photocatalytic processes) and/or in the presence of hydrogen peroxide. However, the mechanism of H 2 O 2 activation on niobia-based catalysts was found to be different from that previously established for other transition metal oxides known for their ability to generate reactive oxygen species (ROS) through Fenton-like mechanism. This short review aims at summarizing recent advances in understanding the reactivity of Nb 2 O 5 -based catalysts in catalytic activation of H 2 O 2 and degradation of various organic pollutants (e.g. organic dyes, antibiotics and organosulfur compounds). Particular attention is paid to the description of mechanism of H 2 O 2 activation and organics degradation, unraveling the relationship between surface properties and reactivity of Nb 2 O 5 in activation of H 2 O 2 as well as pointing out recent approaches to improve the reactivity of niobia-based nanomaterials in degradation of selected organic pollutants in the presence of H 2 O 2. [ABSTRACT FROM AUTHOR]

Hydrodynamic cavitation (HC) is not only a promising wastewater treatment technology but also an efficient heat generation method. In this work, the HC degradation of several organic dyes was carried out and the related heat generation was studied. The effects of geometrical parameters (orifice angles (α = 0 ° and + 45 °) and orifice numbers (n = 3-9)) and experimental parameters (2.0-4.0 bar pressures, 30-60 °C temperatures and 5.0-15 mg/L concentrations) on Auramine 0 degradation and heat generation in orifice plate HC system are investigated. TOC analysis is performed to determine the mineralization degree of Auramine 0 solution. The generated intermediates are detected by LC-MS. In addition, the produced free radicals in HC process are identified by adding some trapping agents. The results showed that the HC technology has high mineralization and strong heat generation abilities in degradation processes of organic pollutants. For 6-orifice plate, 4.0 bar pressure, 5.0 L solution volume and 10 mg/L concentration, 81.39% degradation ratio of AO was achieved at 90 min cycle moment. And that, 1082.52 kJ heat energy with 40.09% thermal efficiency was obtained during 30 min cycle time. Perhaps, this work may provide a new strategy for simultaneous large-scale organic wastewater treatment and effective heat production recycle. [ABSTRACT FROM AUTHOR]

In order to improve the current environmental pollution caused by discarded pesticide packages in rural areas, and raise awareness of agricultural ecological environmental protection. Rare earth ions (RE3+ = Ce3+, Sm3+, Pr3+, La3+) doped titanium dioxide (TiO2) catalysts were prepared by sol-hydrothermal method and characterized by XRD, SEM, TEM, XPS, BET, UV–vis DRS, PL, EPR, and density functional theory (DFT) calculations. The characterization results showed that the doped rare earth ions replace Ti4+ into the titania lattice. The activity of the RE3+-doped TiO2 photocatalyst was evaluated by degrading methyl orange (MO) and mixed pesticides (also containing pirimicarb, fenthiophos, triadimefon and deltamethrin) under ultraviolet light. Compared with pure TiO2, RE3+-doped TiO2 has significantly improved photocatalytic activity for the degradation of MO and carbamate pesticides. The degradation rate of Sm-TiO2 sample to degrade MO reached 100% within 60 min, and the degradation rate of degrading aphicarb, fenthion, triadimefon and deltamethrin reached more than 90% within 180 min. Sm-TiO2 is the best catalyst. This can be attributed to a synergistic effect of the doping of Sm3+ introduces impurity energy levels and a large number of oxygen vacancies (OVs), which can more effectively capture photogenerated electrons and reduce the recombination rate of photogenerated electrons-holes. In this study, the sol-hydrothermal method was used to develop a high-efficiency catalyst for simultaneous photocatalytic degradation of various organic pollutants in aqueous solutions. [ABSTRACT FROM AUTHOR]

Persulfate-based in situ chemical oxidation (ISCO) has been increasingly used for the remediation of contaminated groundwater and soil. In recent years, there have been numerous studies in the literature on all aspects of the activation of persulfate for contaminant removal at the laboratory scale, including the ways and mechanisms for the activation, the pathways of contaminant degradation, the factors associated with the activation performance, the methods characterizing the processes, etc. In contrast, studies in the literature on the practical use of the activated persulfate at the field scale are fewer, and at the same time have not been reviewed in an organized way. This review was initiated to summarize on the current research on the applications of activated persulfate for actual site remediation, and to extract the knowledge necessary for the formation of applicable technologies. The remediation efficiency and mechanism of activated persulfates by heat, alkaline, metal-based, and electrokinetic activated technologies are described. The major factors including pH, the persistence of persulfate, and the radius of influence and soil property during ISCO remediation applications were presented and discussed. Finally, the rebound process and impact towards microbial communities after in-situ chemical oxidation on site application were discussed.

The photocatalytic degradation mechanism of Ag 2 ZnGeO 4 /g-C 3 N 4. [Display omitted] • Ag 2 ZnGeO 4 /g-C 3 N 4 binary photocatalysts were successfully prepared by wet impregnation. • The formation of heterojunction improved the optical properties of g-C 3 N 4. • The Ag 2 ZnGeO 4 /g-C 3 N 4 exhibited excellent photodegradation of TC. • Superoxide anion radicals played an essential role in the photocatalytic degradation of TC. • A possible Z-scheme of the photocatalytic degradation mechanism was proposed. Accumulation of tetracycline was hazardous to human health and ecosystems. Ag 2 ZnGeO 4 /g-C 3 N 4 heterojunction photocatalysts were successfully prepared by the wet impregnation method. The morphological structure and optical properties of the photocatalysts were measured by a series of characterization methods. Moreover, Ag 2 ZnGeO 4 /g-C 3 N 4 with a loading ratio of 20 % exhibited excellent photocatalytic activity by exploring the Ag 2 ZnGeO 4 loading, catalyst dosage, initial concentration, and initial pH of tetracycline. The degradation efficiency of 20 % Ag 2 ZnGeO 4 /g-C 3 N 4 for 10 mg/L TC was 94.29 % at 0.2 g/L catalyst dosage, and the corresponding first-order reaction rate constant reached a maximum of 0.0199 min−1. In addition, according to the results of the trapping experiments, superoxide anion radical was the major active species. Eventually, a possible Z-scheme of the photocatalytic degradation mechanism was proposed. The heterojunction formed between Ag 2 ZnGeO 4 and g-C 3 N 4 could accelerate the transfer and separation of photogenerated carriers, enhancing the photocatalytic activity. [ABSTRACT FROM AUTHOR]

It is of great significance to explore innovative ways to degrade organic pollutants in wastewater. Here, for the first time, we report a self-powered photocatalytic ozonation water purification system for removing organic pollutants in aquatic environment. A rabbit fur-based rotary triboelectric nanogenerator (RR-TENG) is designed as the power supply of water purification system. As a new TENG-based ozone generation method, spark-surface dielectric barrier discharge (Spark-SDBD) is proposed, which is composed of spark discharge device and surface dielectric barrier discharge (SDBD) device in series and can generate ozone to a maximum concentration of 36.4 mg/m3. Rhodamine B and ciprofloxacin, two typical organic compounds, are selected as simulated pollutants in wastewater, and P25 particles loaded on nickel foam are used as the photocatalyst. Ozone is continuously introduced into the polluted solution through an aeration device, coupled with photocatalysis. Within 80 minutes, it can be observed that Rhodamine B has 100% decolorization and ciprofloxacin is degraded to 99%. This work broadens the field of water purification and provides an effective way to create a cleaner and safer aquatic environment. [Display omitted] • A self-powered wastewater purification system based on RR-TENG by coupling photocatalysis with ozonation is proposed. • By connecting a spark DC, the concentration of ozone generated from TENG-based SDBD device is increased by 4.5 times. • The self-powered wastewater purification system can completely decolorize 150 mL of 30 mg/L Rhodamine B solution within 80 min. • The coupling of ozonation and photocatalysis improves the degradation effect of organic pollutants in wastewater. [ABSTRACT FROM AUTHOR]

The Fenton reaction has been widely used in wastewater treatment processes, and the reaction rate is improved by irradiation with light. In this work, Bi[Fe(CN) 6 ]·4H 2 O was synthesized as a photo-Fenton catalyst by precipitation at room temperature without any stabilizer or capping agent. Two synthesis routes were used and compared; one using K 3 [FeIII(CN) 6 ] solution and the other using K 4 [FeII(CN) 6 ]. When Bi(NO 3) 3 solution was mixed with K 3 [FeIII(CN) 6 ] solution, the Bi[Fe(CN) 6 ]·4H 2 O was obtained. However, the KBi(H 2 O) 2 [Fe(CN) 6 ]·H 2 O was first precipitated by the reaction of Bi3+ with [FeII(CN) 6 ]4-, and this intermediate was transformed into Bi[Fe(CN) 6 ]·4H 2 O. Compared with Bi[Fe(CN) 6 ]·4H 2 O prepared with K 3 [FeIII(CN) 6 ], the photo-Fenton degradation of Rhodamine B (RhB) with Bi[Fe(CN) 6 ]·4H 2 O prepared with K 4 [FeII(CN) 6 ] exhibited a higher activity. It attributed to a smaller particles size of Bi[Fe(CN) 6 ]·4H 2 O prepared with K 4 [FeII(CN) 6 ]. Although Bi[Fe(CN) 6 ]·4H 2 O could degrade RhB in darkness, its activity increased under visible light irradiation. The prepared catalyst also degraded reactive orange 16 (RO) and tetracycline hydrochloride (TC) under visible light irradiation. The degradations of RhB, RO, and TC were confirmed by mass spectrometry. From experimental results, the Bi[Fe(CN) 6 ]·4H 2 O prepared with K 4 [FeII(CN) 6 ] showed high activity and promise as a catalyst for wastewater treatment. [ABSTRACT FROM AUTHOR]

Sphingomonas sp. Cra20 is a rhizobacteria isolated from the root surface of Leontopodium leontopodioides in the Tianshan Mountains of China and was found to influence root system architecture. We analyzed its ability for plant-growth promotion and the molecular mechanism involved by combining the physiological and genome information. The results indicated that the bacterium enhanced the drought resistance of Arabidopsis thaliana and promoted growth mainly through the strain-released volatile organic compounds. The genome consisted of one circular chromosome and one circular plasmid, containing a series of genes related to the plant-growth promotion. Furthermore, multiple copies of cold-associated genes, general stress response genes, oxidative stress genes and DNA repair mechanisms supported its survivability in extreme environments. In addition, the strain had the ability to degrade xylene and 2, 4-D via a variety of monooxygenases and dioxygenases. This provides further information and will promote the application of Cra20 as a biofertilizer in agriculture. • The strain Cra20 enhanced the drought resistance of Arabidopsis thaliana and promoted growth. • The genome consisted of one circular chromosome and one circular plasmid. • Multiple copies of stress response genes and DNA repair mechanisms supported its survivability. • Sphingomonas sp. Cra20 had the ability to degrade xylene and 2, 4-D. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3), which was prepared by a two-step solid-phase synthesis, exhibited catalytic activity in the photodegradation of bromophenol blue under the action of hydrogen peroxide. Mechanical preactivation of BiFeO3 in an atmosphere of argon led to an increase in the photocatalytic activity due to an increase in the specific surface area. Upon reaching an ultimate specific surface area by grinding the catalyst powder in argon, continued grinding in an atmosphere of hydrogen led to a further increase in the photocatalytic activity due to an increase in the surface concentration of oxygen vacancies. [ABSTRACT FROM AUTHOR]

In this study, based on Ag@AgCl/tubular g-C 3 N 4 (Ag@AgCl/TCN) composite, Ag nanoparticles were deposited on its surface to form Ag nanofilm enhanced composite through photoreduction of excessive silver nitrate solution to obtain Ag nanofilm Ag@AgCl/TCN photocatalyst. Finally, Ag nanofilm Ag@AgCl/TCN/Ti photoanode was successfully prepared by silica-sol drop-coating method, and assembled with Cu 2 O/Cu cathode to construct a photocatalytic fuel cell (PFC). Ag nanofilm can not only enhance the light absorption and utilization of Ag@AgCl/TCN/Ti, but also extend its light response wavelength to visible light, and be used as an electron transfer medium to reduce internal resistance. The photocurrent density and the photoconversion efficiency of the Ag nanofilm/Ag@AgCl/TCN/Ti are 8.01 mA·cm−2 and 1.24%, respectively, which are 2.49 and 2.54 times those of the Ag@AgCl/TCN/Ti photoanode, respectively. The first-order kinetic constant and the maximum power density of the Ag nanofilm-coated Ag@AgCl/TCN/Ti-Cu 2 O/Cu PFC system are 0.064 min−1 and 46.37 μW·cm−2, respectively, which are 1.39 and 1.94 times those of the Ag@AgCl/TCN-Cu 2 O/Cu PFC system, respectively. In addition, it degraded more than 95% of rhodamine B, 72.68% of tetracycline and 54.25% of bisphenol A within 60 min. The excellent performance of Ag nanofilm/Ag@AgCl/TCN/Ti-Cu 2 O/Cu is due to the strengthening of Ag nanofilm and the formation of S-type heterojunctions between AgCl and TCN. Free radicals (•Cl, h+, •OH, •O 2 -) and non-radicals (1O 2) are involved in the degradation reaction of RhB degradation. It is worth noting that 6% Ag nanofilm/Ag@AgCl/TCN/Ti-Cu 2 O/Cu has a positive effect on the production of •O 2 -, and its output is approximately 1.89 times that of the Ag@AgCl/TCN/Ti-Cu 2 O/Cu. A series of material characterization experiments have been completed and possible mechanisms of operation have been proposed. This study provides a new scheme for the design and preparation of high-efficiency photoanode of PFC. [Display omitted] • Ag nanofilms first applied to electrode materials and Ag nanofilm/Ag@AgCl/TCN/Ti photoanode was prepared for the first time. • The S-type heterojunction between AgCl and tubular g-C 3 N 4 greatly decreases photogenerated electron-hole recombination. • Ag nanofilm accelerates the electron transmission, extends the absorption band edge and enhances the light utilization. • Ag nanofilms act as electron transfer mediums and can effectively reduce internal resistance. • The collaborative effort of PFC is responsible for the joint action of Ag nanofilm and S-type heterojunction. [ABSTRACT FROM AUTHOR]

Recently, the combination of the piezoelectric effect in the photocatalytic process, referred to as piezo-photocatalysis, has gained considerable attention as a promising approach for enhancing the degradation of organic pollutants. In this investigation, we studied the piezo-photocatalysis by fabricating arrays of barium strontium titanate (Ba 0.7 Sr 0.3 TiO 3 ) nanorods (BST NRs) on a glass substrate as recoverable catalysts. We found that the degradation rate constant k of the rhodamine B solution achieved 0.0447 min -1 using poled BST NRs in the piezo-photocatalytic process, indicating a 2-fold increase in efficiency compared to the photocatalytic process (0.00183 min -1 ) utilizing the same material. This is mainly ascribed to the generation of the piezopotential in the poled BST NRs under ultrasonic vibration. Moreover, the BST NR array demonstrated a hydrogen (H 2 ) production rate of 411.5 μmol g -1 h -1 . In the photoelectrochemical process, the photocurrent density of poled BST NRs achieved 1.97 mA cm -2 at an applied potential of 1.23 V ( E RHE (reversible hydrogen electrode)) under ultrasonic vibrations, representing a 1.7-fold increase compared with the poled BST NRs without ultrasonic vibrations. The measurement results from the liquid chromatograph mass spectrometer (LC-MS) demonstrated the formulation of a degradation pathway for rhodamine B molecules. Moreover, ab initio molecular dynamics (AIMD) simulation results demonstrate the dominance of hydroxyl radicals ( • OH) rather than superoxide radicals ( • O 2 - ) in the degradation process. This study not only benefits the understanding of the principle of the piezo-photocatalytic process but also provides a new perspective for improving the catalytic efficiency for organic pollutants degradation.

Abstract The Z scheme system ZnIn 2 S 4 /RGO/BiVO 4 was synthesized using the hydrothermal method. The activities of hydrogen generation from decomposition of water and the organic pollutants degradation have been evaluated under visible-light irradiation. The Z scheme system can catalyze the hydrogen generation from water splitting and organic pollutants degradation simultaneously under visible light. The presence of organic pollutants can promote the hydrogen generation from water splitting. The activity of hydrogen production is related to the reduction properties of the organic compounds and the highest hydrogen production efficiency obtained in the presence of formaldehyde. The hydrogen production rate, formaldehyde degradation rate, the A.Q.Y. and the η c are determined to be 1687 μmol g−1 h−1, 22.2 mmol g−1 h−1, 22.9% and 13.3% when the formaldehyde concentration is 5 mol L−1, the concentration of the catalyst is 1.5 g L−1, the initial pH of solution is 13. When mixed organic pollutants are added, the system can also have a good activity for hydrogen production and organic pollutants degradation. Furthermore, the mechanism of the Z scheme system ZnIn 2 S 4 /RGO/BiVO 4 for hydrogen generation and simultaneous degradation of organic pollutants has been also discussed. Graphical abstract Image 1077 Highlights • Z scheme system can catalyze hydrogen generation and organic pollutants degradation. • Presence of organic pollutants can promote hydrogen generation from water splitting. • Activity of hydrogen production is related to electrophilicity of organic compounds. • Rate of H 2 production and CH 2 O degradation are 1.687 and 22.2 mmol g−1 h−1. • Z scheme system also has a good activity when mixed organic pollutants are added. [ABSTRACT FROM AUTHOR]

PVC/Ag3PO4 composites are prepared by solution-dipping method, and the as-prepared composites are heat-treated to release HCl from PVC molecules to obtain conjugated derivative of PVC/Ag3PO4(CDPVC/Ag3PO4) composites. The CDPVC/Ag3PO4 composites are characterized by XRD, SEM, UV-vis DRS, PL and XPS. The effects of preparation conditions on the visible-light photocatalytic performances of CDPVC/Ag3PO4 composites are investigated by evaluating the decomposition of methyl orange under visible light irradiation. The results reveal that the modification of CDPVC is beneficial to the dispersion of Ag3PO4 particles, and it can obviously improve the absorbance of the CDPVC/Ag3PO4 composites in the range of visible light and the charge separation efficiency. The CDPVC/Ag3PO4 composites exhibit excellent visible-light photocatalytic acitivity and stability when the mass percentage of PVC to Ag3PO4, heat-treatment temperature and time are 0.03%, 130 ℃, and 2 h, respectively.

[Display omitted] • This review discusses new strategies to improve the applications of photosystems. • Numerous modification technologies were explained and highlighted. • Some vital environmental factors influencing the photoreaction were also outlined. • All types of semiconductor heterojunctions were reviewed in detail. • This review helps to develop efficient and cost-effective photocatalytic systems. Visible-light-driven photochemistry is an attractive strategy for solar light utilization and renewable energy harvesting for environmental improvement. To obtain a powerful photochemical reaction, it is necessary to construct an efficient, stable, and cost-effective semiconductor system. Herein, we try to provide a comprehensive review to discuss the new strategies that have been proven by recent impactful investigations to improve photocatalytic systems and their applications in industrial wastewater treatment. Particularly, the preferred characteristics, such as strong redox ability, appropriate band edge positions, long-term stability, efficient charge-separation efficiency, and narrow band gap energy, are required to improve the photodegradation rate of photocatalysts against different organic pollutants in wastewater. Therefore, numerous modification technologies, like element doping, defect engineering, heterojunction construction, and morphological optimization, were outlined to control the photodegradation ability of developed photo-systems. In addition, the review involves some sophisticated technologies to fabricate different nano-semiconductor photocatalysts. Besides, our study introduces some vital factors like photocatalyst loading, reaction temperature, pH value, light intensity, substrate concentration, scavengers, and catalyst morphology that influence the photoreaction. Finally, we believe that the findings of this discussion will help to develop efficient and cost-effective photocatalytic systems for eliminating organic pollutants in industrial wastewater. [ABSTRACT FROM AUTHOR]

Degradation of organic pollutants through O 2 activation catalyzed by transitional metals is challenging without addition of external chemicals and input of energy. We prepare a novel Fe based catalyst by compositing carbon, iron phosphide (Fe x P), iron carbide (Fe x C), Fe0 and Cu NPs, which can continuously activate O 2 to produce high amount of 1O 2 ,·O 2 - and·OH radicals in a wide pH range. DFT calculation discloses that O 2 molecules are dissociated into *O or exist as O-O in various configurations. The Fe-O 2 , Cu-O 2 and FeP-O 2 surfaces can react with H 2 O molecules to generate *OOH, *OH and/or OH-. The sorbed-O 2 intermediates on Fe x C surface might be released as 1O 2 or·O 2 -. The oxidative O 2 -sorbed surfaces and in-situ produced oxygen reactive species contribute to the efficient and pH-indenpendent degradation of organic pollutants. Cu NPs accelerate Fe2+/Fe3+ cycles and offer impetus to initiate O 2 activation due to the potential difference between Fe and Cu. The recycling test and XPS results confirm that the mutual electron transferring among carbon, Fe x C, Fe x P, Fe and Cu maintains reactivity and stability of the catalysts. [Display omitted] • Cooperation of Fe x P, Fe 3 C/Fe0 and Cu promotes efficient activation of O 2 by Fe x P-FeCu. • Abundant·OH, O 2 ·- and 1O 2 are produced in Fe x P-FeCu/O 2 system without addition of H 2 O 2. • DFT calculation shows that sorbed-O 2 reacts with H 2 O on catalytes surface to produce *OH. • The sorbed-O 2 intermediates on Fe 3 C surface might be released as 1O 2 or·O 2 -. • Transfer of electrons from Fe to C or P enhances the stability of Fe 3 C or FeP crystals. [ABSTRACT FROM AUTHOR]

Fenton reaction has been widely used to treat wastewater containing dyes, herbicides, antibiotics, and landfill leachate because of its convenience and strong oxidation ability. The rational design and preparation of efficient and stable Fenton catalysts have been the focus of research. In this study, graphene-magnetite hollow hybrid microspheres were synthesized by a facile aerosolized spray drying route utilizing ferric ion and graphene oxide (GO) solution as the precursor. The results showed that uniform hybrid microspheres with possess hollow structure, high saturation magnetization and high Fenton catalytic activity with 30 wt% graphene (30G-FeO) as catalyst. By the electrochemical analysis, a two-electron dominated process has been demonstrated to explain higher electrocatalytic activity. Accordingly, a novel electro-Fenton (EF) system with the 30G-FeO cathode was established working at acidic condition. The 30G-FeO cathode material possessed highly EF catalytic activity after prolonged cycling. Inspired by the wonderful intrinsic properties and the easy fabrication procedure, the as-prepared 30G-FeO could be promising candidates as potential cathodic materials for high-performance EF oxidation. [ABSTRACT FROM AUTHOR]

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Energy shortage and environmental pollution have seriously threatened our environment, so it is urgent to develop efficient photocatalysts to solve these dilemmas. Here, we firstly designed and manufactured the self-supporting double Z-scheme [g-C 3 N 4 /polymethylmethacrylate (PMMA)]//[TiO 2 /polyaniline (PANI)/PMMA]//[self-assembled 3, 4, 9, 10-perylene tetraformyl diimide (PDI)/PMMA] tricolor-typed microfiber oriented-heterostructure photocatalyst (marked as TMOP) via a tri-axial parallel electrospinning. The optimized TMOP simultaneously manifests prominent hydrogen generation efficiency (536.7 μmol h−1 g−1) and splendid degradation rates for four different leuco antibiotics of ciprofloxacin (88.99%, 90 min), tetracycline hydrochloride (91.15%, 80 min), chlortetracycline hydrochloride (77.55%, 150 min), levofloxacin (69.51%,150 min) and colored dye methylene blue (92.50%, 50 min) under simulated sunlight illumination, validating perfect tri-functional features. The dramatically heightened photocatalytic activity of TMOP mainly benefits from the morphology, heterostructure and components of tricolor-typed microfiber, which not only increases the active sites, but also broadens the absorption range of solar spectrum by using the wide spectral characteristics of PDI. More importantly, the synergistic effect between conductive polyaniline and one-dimensional double Z-scheme oriented-heterostructures accelerates the oriented and rapid transmission of carriers in multiple paths, thus greatly reducing the possibility of carriers recombination and retaining the strong redox capacity of carriers. Additionally, TMOP with self-supporting feature presents remarkable recoverability. The construction mechanism of tricolor-typed microfiber and TMOP as well as double Z-schem preserving the strong redox capacity of carriers photocatalytic mechanism are advanced. [Display omitted] • A double Z-scheme tricolor-typed microfiber oriented-nanostructure is first designed. • Photocatalyst is constructed by facile tri-axial parallel electrospinning technology. • Double Z-scheme oriented-heterostructure boosts separation of photo-induced carriers. • Double Z-scheme heterostructure endows charge carriers with strong redox capability. • Photocatalyst displays H 2 evolution and degrading antibiotics and dye tri-function. [ABSTRACT FROM AUTHOR]

Photocatalysis has been regarded as one of the promising technologies in treating pollutants. Visible light-driven photocatalysis has attracted attention due to its potential in utilizing a greater portion of sunlight. Silver phosphate (Ag 3 PO 4) is a visible light active photocatalyst that exhibited 90% quantum efficiency and showed excellent photocatalytic performance in decomposing pollutants. This review provides an overview of the selection of suitable synthesis methods used to obtain desirable Ag 3 PO 4 and Ag 3 PO 4 -based for different types of photocatalytic applications utilizing visible light. The challenges and the prospects of improving the performance of Ag 3 PO 4 and Ag 3 PO 4 -based visible light active photocatalysts have been discussed. Ag 3 PO 4 and Ag 3 PO 4 -based visible light active photocatalysts for environmental remediation. [Display omitted] • Ag 3 PO 4 as photocatalysts. • Ag 3 PO 4 as visible light active photocatalysts. • Doped Ag 3 PO 4 as visible light active photocatalysts. • Effect of dopants on the photocatalytic activity of Ag 3 PO 4 • Ag 3 PO 4 -based materials for different photocatalytic applications [ABSTRACT FROM AUTHOR]

Silver phosphate (Ag 3 PO 4) has attracted considerable attention as a promising visible light-active photocatalyst. Ag 3 PO 4 and 1, 3, and 5% La-doped Ag 3 PO 4 have been synthesized using a facile precipitation method. Powder X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and scanning electron microscopy (SEM) have been used to characterize the synthesized materials. Both Ag 3 PO 4 and La-doped Ag 3 PO 4 exhibited body centered cubic structure with no impurities as confirmed using XRD analysis. FTIR measurements of the synthesized materials showed the presence of phosphate and La–O groups. From the SEM images, Ag 3 PO 4 has tetrapod particles that change to irregular particles upon La doping. The incorporation of La into the lattice also changes the band gap energy of Ag 3 PO 4 which was confirmed by DRS. The synthesized materials were then tested for the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) under visible light irradiation. 1% La-doped Ag 3 PO 4 was found to exhibit outstanding photocatalytic performance where it completely degrades MB and MO within 60 min. Additionally, it was also found that La-doped Ag 3 PO 4 showed improved performance of Cr(VI) photoreduction under visible light irradiation compared to Ag 3 PO 4. La-doped Ag 3 PO 4 for photocatalytic degradation of methyl orange and methylene blue and reduction of Cr(VI) under visible light irradiation. [Display omitted] • Silver phosphate and La-doped silver phosphate. • Ag 3 PO 4 and La-doped Ag 3 PO 4. • Ag 3 PO 4 and La-doped Ag 3 PO 4 as photocatalyts. • The band gap energy tuned La-doped Ag 3 PO 4. • Photocatalytic degradation of dyes and photoreduction of Cr(VI) using La-doped Ag 3 PO 4. [ABSTRACT FROM AUTHOR]

Abstract: TiO2 nanoparticles with improved photocatalytic activity (TiO2NPs-NaCl(R)) were synthesized through a well controlled sol–gel process in the presence of NaCl. Instead of being incorporated into the lattice of TiO2, the added sodium chloride can be completely removed from the resultant TiO2NPs-NaCl(R) by DI water. The results showed that TiO2NPs-NaCl(R) has 2 times more surface hydroxyl groups than that in TiO2NPs prepared without adding NaCl. Consequently TiO2NPs-NaCl(R) exhibits an enhanced photocatalytic activity for degradation of methylene blue (MB) and HCHO under UV irradiation. This research provides a simple and economic approach to improve photocatalytic performance of TiO2 related materials. [Copyright &y& Elsevier]

In this work, we report on the degradation of methyl-red (2-(4-Dimethylamino-phenylazo)-benzoic acid -- C.I. 13020) under UV irradiation in the presence of nanosized ZnO and TiO2. Oxide nanocrystals with controlled size were synthesised by using non-hydrolytic approaches and tested for the photocatalysed degradation. The performances of the immobilised nanoparticles were compared with their commercial counterparts after immobilization onto a solid support. The influence of some experimental conditions, namely pH and dye concentration, were investigated by monitoring the dye decoloration spectrophotometrically. Several intermediate by-products were identified by HPLC-MS, showing that two different mechanisms were operative during the photocatalytic oxidation. [ABSTRACT FROM AUTHOR]

Organic-capped anatase TiO2 nanocrystals were tested for the photocatalyzed degradation of a target compound, the textile dye Uniblue A, in homogeneous organic solutions. The photocatalytic activities of nearly spherical and rod-like titania nanoparticles under UV irradiation were comparatively investigated with reference to their bulk commercial counterpart, TiO2 Degussa P25.Preliminary data clearly show that different degradation paths can be initiated, depending on the size of the titania particles, on the nature of the reaction medium and on the presence of dissolved oxygen. The fast reductive decomposition of the conjugated ring structure of Uniblue A appeared to be the dominant pathway in the presence of nanosized TiO2, even in aerated solutions, while the overall photocatalytic efficiency was found not to be affected by the nanocrystals morphology. [Copyright &y& Elsevier]

In this work, easily processable and highly crystalline ZnO and TiO2 nanoparticles, with a narrow size distribution, obtained by using novel non-hydrolytic synthetic approaches were both tested for the photocatalyzed degradation of an organic dye, methyl red (2-(4-Dimethylamino-phenylazo)-benzoic acid)—C.I. 13020) and their behaviour comparatively examined with respect to TiO2 and ZnO commercial powders. The experiments were carried out using semiconducting oxides under UV and visible light illumination. Preliminary studies on the influence of various experimental factors as pH and dye concentration were performed. The obtained results demonstrated a high photocatalytic efficiency of nanosized semiconducting particles. [Copyright &y& Elsevier]

A series of N-TiO 2 /Ti 3 C 2 composites are constructed via ultrasonically treating pre-synthesized N-TiO 2 and Ti 3 C 2. Improved sonophotocatalytic activity is demonstrated by the tests of contaminant degradation and nitrogen fixation. [Display omitted] • The N-TiO 2 /Ti 3 C 2 composites are constructed under ultrasound irradiation. • The intimate interfacial contact is verified by a series of characterizations. • Improved sonophotocatalytic degradation and nitrogen fixation are confirmed. • The synergic effect of N 2p doping and Ti 3 C 2 coupling contribute to the enhancement. • The order of catalytic behavior was sonophotocatalysis＞sonocatalysis＞photocatalysis. Herein, a series of N-TiO 2 /Ti 3 C 2 (N-TTC x) composites are constructed via ultrasonically treating pre-synthesized N doped TiO 2 and Ti 3 C 2 at room temperature. The intimate contact between N-TiO 2 and Ti 3 C 2 is verified by the transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. And, the N-TTC 0.06 composites exhibit the best sonophotocatalytic performance, which is 1.9 times and 8.8 folds higher than that of TiO 2 for pollutant degradation and nitrogen fixation, respectively. What's more, sonophotocatalytic degradation of pollutants and nitrogen fixation shows larger efficiency compared with that of photocatalysis and sonocatalysis, which is attributed to the synergistic effect between sonocatalysis and photocatalysis in the sonophotocatalytic process. Moreover, taking N-TTC 0.06 for example, the three cycles of sonophotocatalytic degradation of Rh-B and nitrogen fixation as well as the unchanged X-ray diffraction before and after sonophotocatalytic nitrogen fixation all confirm the stable sonophotocatalytic behavior of N-TiO 2 /Ti 3 C 2 composites. The improved sonophotocatalytic activity is attributed to the decrease of band gap by N 2p doping level and the separation/transfer improvement of photoinduced carriers by Ti 3 C 2 , which are demonstrated by UV–vis absorption spectra, photoelectrochemical tests, Nyquists plots, and Mott-schottky plots. This study confirms that the designed N-TiO 2 /Ti 3 C 2 composites exhibit great potential application in sonophotocatalytic pollutant degradation and nitrogen fixation. [ABSTRACT FROM AUTHOR]

A novel structural composite (Fe-N/FeS@C) was synthesized via a self-doping strategy by the pyrolysis of a solid mixture of lignosulfonate and ferric nitrate pretreated by mechanical activation. The as-synthesized composite contained 7.5 wt% of single atomic iron moieties and 16.0 wt% of encapsulated FeS nanoparticles, with a high surface area of 1095.81 m2 g–1 and plentiful micropores and mesopores (0.4–10 nm). The Fe-N/FeS@C composite was confirmed to possess outstanding catalytic activity for sulfite activation in the degradation of methylene blue, with a high reaction rate constant (0.77 g g–1 min–1) and long cycling stability (83.1% of initial activity retention after 10 recycles). Moreover, the composite exhibited satisfactory activity recovery via a simple rinsing process with ethanol and HCl, and performed well in a wide pH range of 3–11. Density functional theory calculation results further demonstrated that the reaction energy of the rate-determining step, in which SO 3 •− was produced from SO 3 2– on atomic Fe moieties, was lower than that of the formation of FeSO 3 + by Fe3+ and SO 3 2–. The excellent performance of Fe-N/FeS@C was mainly attributed to the combination of the high mass loading of active sites of atomic Fe moieties anchored into carbon matrix with encapsulated FeS nanoparticles. This study provides new insight into the development of environment-friendly, stable and atomic dispersion iron composite for sulfite activation to efficiently remove organic pollutants. [Display omitted] • A composite (Fe-N/FeS@C) was developed by MA and pyrolysis technology. • Activation of sulfite using the composite exhibits a superior catalytic activity. • Both SO 4 •− and •OH are identified as the main reactive oxygen species. • Single atomic irons and encapsulated FeS in the catalyst are key active sites. [ABSTRACT FROM AUTHOR]

The Fe3+-O-Mn3+/2+ hybrid bonds were constructed on the surface of the amorphous and porous silica molecular sieve (MCM-41) by a three-step method that involved impregnation, hydrothermal incorporation, and annealing. The obtained FeMn-MCM-41 has an amorphous, less-ordered mesoporous structure with uniformly distributed Fe and Mn and a large specific surface area. It exhibits high activity, good recyclability, and wide pH applicable range for the heterogeneous catalytic ozonation (HCO). The TOC removal of methyl orange at high concentration of 327.5 ​mg ​L−1 is 78% on FeMn-MCM-41, which is not only much higher than the value of single ozonation (43%) but also much higher than the value on mixed catalysts of Fe-MCM-41 and Mn-MCM-41 (52%). We demonstrate that large amounts of the Fe3+-O-Mn3+/2+ hybrid bonds were created on the surface of porous silica, and the partial electron migration occurs in the hybrid Fe3+-O-Mn2+ (or Fe3+-O-Mn3+) bonds. As is well known, Fe3+ and Mn3+/2+ are very strong and weak Lewis acid sites in their oxides, respectively, and the partial electron migration lowers the acidity of Fe3+ sites and in the meantime increases the acidity of Mn3+/2+ sites, making both sites more suitable for catalytic production of free hydroxyl radicals (•OH). The synergetic effect of Fe3+ and Mn3+/2+ significantly improve the intrinsic activity of the FeMn-MCM-41 for HCO. This work may offer a new strategy for developing efficient mesoporous catalysts for catalytic ozonation. Fe and Mn were incorporated into MCM-41 molecular sieve by a hydrothermal-annealing method and the obtained FeMn-MCM-41 exhibits a high activity and recyclability for the heterogeneous catalytic ozonation of organic pollutants. [Display omitted] • Bimetallic FeMn-MCM-41 was prepared by incorporating Fe and Mn into MCM-41. • FeMn-MCM-41 exhibits high activity and stability for heterogeneous catalytic ozonation (HCO). • FeMn-MCM-41 greatly improves the production of free hydroxyl radical. • Synergic effect of Fe and Mn enhance the intrinsic activity of active centers for HCO. • Mesoporous structure of FeMn-MCM-41 provides large numbers of active centers per mass of catalyst. [ABSTRACT FROM AUTHOR]

• {0 0 1}-faceted TiO 2 nanosheet arrays/graphene foam was successfully prepared. • The TiO 2 /graphene foam exhibits prominent removal ability and recyclability. • A good linkage between TiO 2 and graphene strengthen interfacial charge transfer. • The {0 0 1} facets facilitate surface molecular oxygen activation. Exposing high-energy active facets for nanocrystals has received increasing attentions due to its intrinsic surface-dependent properties in extensive applications. Unfortunately, most anatase TiO 2 crystals were dominated by the thermodynamically stable {1 0 1} facets instead of the much more catalytically active {0 0 1} facets. Meanwhile, the photo-generated electrons and holes in TiO 2 might experience a rapid recombination, which significantly diminishes the efficiency of the photocatalytic reaction. Herein, we integrated {0 0 1} facets TiO 2 nanosheet arrays into a free-standing graphene foam through a facile vacuum filtration process combined with a solvothermal method. Uniformly distributed TiO 2 nanosheet arrays were in situ intercalated into interlayers of flexible graphene foam and were simultaneously anchored on its surface to form 3D hierarchical porous architecture, which was highly appreciated for its easy separation and recycling after photocatalytic process. The multifunctional TiO 2 /graphene foam exhibited superior photocatalytic activity, and the rate constants (k) of the TiO 2 /graphene foam towards degradation of methyl orange (MO) and phenol were 4, 8.7 times higher than commercial P25, respectively. Inspiringly, the TiO 2 /graphene foam also achieved high efficiency in Cr(VI) photoreduction with 92% removal yield. The remarkably photocatalytic capability of the TiO 2 /graphene foam was attributed to the synergistic effects arising from intrinsic single crystalline TiO 2 with high percentage exposure of {0 0 1} facets, as well as a good linkage between TiO 2 and graphene, which could facilitate the surface catalytic reaction by providing abundant reactive sites for an effective molecular oxygen activation and strengthening the interfacial charge transfer both in-plane and vertical transportation. The recycling experiments presented these flexible foam catalysts were stable and could be reused with high efficiency after 12 runs. This work would provide a feasible strategies to design outstanding TiO 2 -based photocatalysts with highly reactive {0 0 1} facet, and also offer more extensive possibilities in a broad application range. [ABSTRACT FROM AUTHOR]