In order to develop efficient and green catalyst for organic pollutants removal, magnetic carbon supported Prussian blue nanocomposite Fe3O4@C/PB was prepared for the first time. The performance of ...Fe3O4@C/PB in activating peroxymonosulfate (PMS) for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated. 2,4-DCP could be effectively degraded under the “Fe3O4@C/PB + PMS” system within a broad pH range of 2–9. Without pH adjustment (pH 3), 2,4-DCP (20 mg/L) was completely degraded in 50 min along with a 70% removal of TOC; while the required time for complete degradation of 2,4-DCP was shortened to 40 min under initial solution pH at 7. Fe3O4@C/PB could also activate PMS for the degradation of phenol, Acid Orange II, Reactive brilliant red X-3B, Rhodamine B and Methylene blue. The degradation rates higher than 95% could be achieved for all these contaminants within the time scale of 15–60 min. The studies of radical-quenching and electron paramagnetic resonance demonstrated that singlet oxygen (1O2) and superoxide radicals (O2−), rather than sulfate (SO4−) and hydroxyl (OH) radicals, were the dominant species responsible for the oxidation of organic pollutants. The plausible mechanism of the catalytic degradation was proposed and the enhanced activity of Fe3O4@C/PB was assumed to be related to the increased electron transfer owing to the synergic effect between the magnetic carbon and the mixed-valence units in PB. Fe3O4@C/PB is promising in wastewater treatment owing to its high efficiency, excellent stability and reusability, environmental friendliness and magnetic separability.
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•Magnetic carbon supported Prussian blue nanocomposite was firstly reported.•Fe3O4@C/PB exhibited high activity for the degradation of 2,4-DCP with PMS.•1O2 and O2− instead of SO4− and OH were dominant ROS in Fe3O4@C/PB + PMS system.•Fe3O4@C/PB + PMS system showed general applicability for removing organic pollutants.•The magnetically separable catalyst exhibited good stability and reusability.
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•Review on silver-based semiconductor Z-scheme photocatalytic systems.•The roles of metallic Ag in this system are deeply discussed.•Special attention has been paid to the ...photocatalytic process and mechanism.•Novel silver-based semiconductor/MOFs Z-scheme photocatalysts are elaborated.•The future development challenges and prospects of this system are presented.
Silver-based semiconductor photocatalysts are promising materials for solving environmental and energy issues due to their strong optical absorption, excellent quantum efficiency and photoelectrochemical properties. However, the uncontrollable photocorrosion and high use cost of single silver-based semiconductor photocatalysts limit its practical application. The construction of Z-scheme photocatalytic systems that mimic natural photosynthesis can not only enhance the photocatalytic activity of silver-based semiconductor photocatalysts, but also improve their stability and reduce the use costs. This critical review concisely highlights the basic principles of Z-scheme photocatalytic systems, and discusses the construction of silver-based semiconductor Z-scheme photocatalytic systems and the roles of metallic Ag in there and summarizes the synthesis methods of silver-based semiconductor Z-scheme photocatalytic systems. Then, a series of the solar-driven applications are elaborated, including organic pollutants degradation, hydrogen production, and carbon dioxide reduction. Meanwhile, the mechanism and difficult level of these photocatalytic reactions are also described. Besides, metal organic frameworks (MOFs) as a novel type of photocatalysts have attracted growing attention. The novel combination of silver-based semiconductors with typical photoactive MOFs is highlighted based on the Z-scheme photocatalytic systems. Eventually, the future challenges and prospects in the development of silver-based semiconductor Z-scheme photocatalytic systems are presented.
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•A new Bi2WO6/BiOI@Ag3PO4 catalyst was prepared by one-step hydrothermal method.•The introduction of Ag3PO4 enhanced evidently the photoelectric properties.•High-efficient ...photocatalytic degradation of BPA and cefepime was presented.•The high photocatalytic activity was due to the double-heterojunction structure.•Photocatalytic degradation could enhance the biodegradability of cefepime solution.
A flower-globular photocatalyst (Bi2WO6/BiOI@Ag3PO4-5) with symmetric double-heterojunction structure and low Ag-content was successfully fabricated for the first time by precipitation and one-step hydrothermal process. The loading of Ag3PO4 evidently enhanced the photoelectric properties of photocatalysts. Bi2WO6/BiOI@Ag3PO4-5 provided an ideal photocatalytic activity towards the degradation of bisphenol A (BPA) and cefepime under simulated sunlight, and it also exhibited well photocatalytic stability. For BPA degradation, the recommend photocatalyst provided nearly 100% of degradation efficiency and 65.4% TOC removal by the simulated sunlight irradiation of 120 min, while for cefepime degradation, it offered the degradation efficiency of 98.2% and the TOC removal efficiency of 33.4%. The mechanism of photocatalytic activity enhancement was owing to the loading of Ag3PO4 and the developed double-heterojunction structure, by which the absorbance of visible light, the separation of electron/hole (e–/h+) pairs and carrier mobility were enhanced evidently. It was found that superoxide anion radical (∙O2–) played the major role in BPA degradation, while hydroxyl radical (∙OH) and hole (h+) together played the key role in cefepime degradation. The two pathways for BPA and cefepime degradation were respectively proposed by identifying the byproducts formed during the degradation. In addition, it was found that the photocatalytic degradation of cefepime evidently enhanced the biodegradability of the solution.
Highly efficient photocatalysts have great development prospects in wastewater treatment, especially in the degradation of organic pollutants and reduction of inorganic heavy metal ions. Herein, a ...Z-scheme ZnTiO3/Zn2Ti3O8/ZnO ternary photocatalyst was prepared by the solvothermal-calcination method and the influence of the content of tetrabutyl titanate precursor and different reaction temperature on the crystal phase structures, photoelectrochemical properties and photocatalytic activities of the samples were investigated. Due to its unique Z-scheme structure and suitable band gap position, which is favorable for the efficient migration and separation of photo-generated electrons and holes and the improvement of photocatalytic redox reaction capability, the samples show excellent performance for the degradation of organic pollutants and reduction of heavy metal Cr(VI) ions. Based on a series of characterization analyses, a possible Z-scheme photocatalytic mechanism is proposed. This work provides a simple preparation method for fabrication of multivariate heterojunction photocatalyst for degradation of organic pollutants and removal of heavy metal ions.
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•A two-step route for building ZnTiO3/Zn2Ti3O8/ZnO nanostructure was developed.•Experiment parameters on the crystal structure and photocatalytic performance were optimized.•The excellent removal efficiency for organic pollutants and Cr(VI) ions were obtained simultaneously.•A unique Z-scheme could illuminate the high removal performance.
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•g-C3N4-VN Ns with homogeneous nitrogen vacancy distribution has been synthesized.•Vacancy modification creates energy disordered interfaces enabling good exciton dissociation.•The ...facilitated exciton dissociation leads to remarkable OH generation.•Enhanced OH generation enable g-C3N4-VN Ns show high photocatalytic performance.
Polymeric materials are promising candidates as photocatalysts for environmental purification, however their catalytic performance are still unsatisfactory mainly due to the strong Coulomb interactions between electron and hole that leads to fast charge recombination. Herein, taking graphitic carbon nitride as an example, we verify that installing carbon nitride nanosheets with nitrogen vacancy could break the intrinsic electronic state distribution, forming energy disordered interfaces around the vacancies with the energy difference as large as 0.35 eV. Such a large energy difference is found energetic enough to overcome the strong Coulomb interactions between electron and hole for hot electron and hole generation, as a result showing high electron-hole separation efficiency. Benefited from these advantages, the as prepared material shows remarkable photocatalytic performance toward organic pollutants degradation. The improved catalytic performance is originated from the promoted exciton dissociation that leads to ultra high hydroxyl radical generation. This study offers a new understanding of the excitonic effects for designing advanced polymeric photocatalyst for energy and environment related applications.
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•Iron-containing mesoporous silica (MFS) was successfully prepared from iron tailings.•MFS was used as an effect activator for peroxymonosulfate (PMS) activation.•MFS showed excellent ...photocatalytic degradation efficiency for organic pollutants.•There were radical pathway and non-radical pathway in MFS/PMS/vis systems.
Solid waste and water pollution are global environmental problems that need to be urgently solved. Using industrial solid waste to treat organic pollutant wastewater might be a good strategy to solve two problems. Herein, iron tailings were used to prepare iron-containing mesoporous silica (MFS) materials under a one-step hydrothermal route. The as-prepared MFS showed excellent photocatalytic degradation efficiency and stability over a wide pH range for five typical organic pollutants. Further degradation test using tap water and Xiangjiang River water notably confirmed its practical application. Quenching and ESR experiments revealed radical (including sulfate (∙SO4−), hydroxide (·OH), and superoxide (·O2−) radicals) and non-radical (including single oxygen (1O2)) pathways worked together in the MFS/PMS/vis system. The cost estimation of the waste-derived MFS materials indicated that the raw material cost could be reduced by $129.8 per kilogram compared to the conventional method. This strategy not only provides a possible solution to iron tailings solid waste problem, but also develops a benign approach to the design and preparation of heterogeneous catalysts. The as-prepared materials have great potential in wastewater treatment, and follow the idea of treating waste with waste to achieve sustainable development.
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•Dual-Z-scheme AgBr/β-Ag2WO4/g-C3N4 ternary composites were fabricated.•The photocatalyst displayed excellent performance for Rhodamine B and tetracycline hydrochloride ...degradation.•The rate constant has significant enhancement compare to single component.•The separation and transfer of the photoinduced charge carriers are efficiently promoted.
The speedy recombination of photoexcited charge carriers is one of the major reasons for the unsatisfactory of semiconductor photocatalysts. Herein, AgBr/β-Ag2WO4/g-C3N4 ternary composites with dual Z-scheme band alignment were constructed for colored Rhodamine B and colorless tetracycline hydrochloride degradation. The crystal structure, micro-nano structure, chemical composition, optical and electrochemical properties of the obtained photocatalysts were thoroughly investigated. The optimized AgBr/β-Ag2WO4/g-C3N4 displayed exceptional photocatalytic activities toward Rhodamine B and tetracycline hydrochloride degradation. The dramatically improved catalytic performance could be ascribed to the dual Z-scheme transfer channel of the charge carriers. It is anticipated that this work could offer a novel sight into constructing effective photocatalyst for environmental remediation.
Production of cost-efficient composite materials with desired physicochemical properties from low-cost waste material is much needed to meet the growing needs of the industrial sector. As a step ...forward, the current study reports for the first time an effective utilization of industrial metal (inorganic) waste as well as fall leaves (organic waste), to produce three types of nanomaterials at the same time; “Titanium Doped Activated Carbon Nanostructures (Ti-ACNs)”, “Nanocellulose (NCel)”, and combination of both “Titanium Doped Activated Carbon Cellulose Nanocomposite (Ti-AC-Cel-NC)”. X-ray diffraction (XRD), transmission electron microscopy (TEM) and microanalysis (EDXS) measurements reveal that the Ti-ACNs material is formed by Ti-nanostructures, generally poorly crystalized but in some cases forming hexagonal Ti-crystallites of 15 nm, embedded in mutated graphene clouds. Micro- Fourier transform infrared spectroscopy (micro-FTIR) confirms that the chemical structure of NCel with bond vibrations between 1035 to 2917 cm−1 remained preserved during Ti-AC-Cel-NC formation. The prepared materials (Ti-ACNs, Ti-AC-Cel-NC) have demonstrated rapid removal of organic pollutants (Crystal Violet, Methyl Violet) from wastewater through surface adsorption and photocatalysis. In the first 20 min, Ti-ACNs have adsorbed ≈87% of the organic pollutants and further photocatalyzed them up to ≈96%. When Ti-ACNs are combined with NCel, their efficiency is increased of about four times. This performance originates from the adsorption by mutated graphene-like carbon and assisted photocatalysis by Ti nanostructures as well as the good supporting capacity of NCel for the homogenous Ti-ACNs distribution.
Rapid Removal of Organic Pollutants by Titanium Doped Activated Carbon - Cellulose Nanocomposite Synthesized from Waste Display omitted
•Three types of nanomaterials (Ti-ACNs, NCel, Ti-AC-Cel-NC) were synthesized purely from inorganic and organic waste.•TEM and SAED findings reveal the formation of hexagonal Ti-crystallites of 15 nm, embedded in mutated graphene clouds.•Micro-FTIR analysis confirms structural stability of NCel upon impregnation of Ti-ACNs to form Nanocomposite.•Prepared nanomaterial demonstrated removal of ≈87% of the organic pollutants from wastewater in less than 20 min.
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•The effects of GA on organic pollutants degradation in the Fenton-like system were systematically investigated.•GA was used as a ligand and reductant to promote the Fe(III)/Fe(II) ...cycles.••O2– and •OH play an essential role in the degradation of ATR in the Fe(III)/GA/H2O2 system.•High concentration of •OH and RSE were obtained in the Fe(III)/GA/H2O2 system.
Herein, glyoxylic acid (GA) was incorporated into the Fenton-like (Fe(III)/H2O2) system to rigorously examine its impact on the degradation of organic pollutants. It was found that the degradation efficiencies of atrazine (ATR), ofloxacin (OFL), rhodamine B (RhB), and carbamazepine (CBZ) in the Fe(III)/GA/H2O2 system were ∼95%, and the apparent ATR degradation rate constant (1.60 × 10−2 min−1) was 4-fold as high as that (0.40 × 10−2 min−1) in the Fe(III)/H2O2 system at pH 3.6. The UV–vis spectral and cyclic voltammetry (CV) analyses demonstrated that GA could be used as a ligand and reductant to coordinate and reduce Fe(III), thereby promoting the Fe(III)/Fe(II) cycles in the Fenton-like process. Testing results for reactive oxygen species (ROS) confirmed that superoxide ions (•O2–) and hydroxyl radicals (•OH) respectively undertake the Fe(III)/Fe(II) cycles and ATR degradation in the Fe(III)/GA/H2O2 system. The reaction stoichiometric efficiencies (RSE) in the Fe(III)/GA/H2O2 system (37.5%–76.9%) were significantly higher than those (2.8%–4.9%) in the Fe(III)/H2O2 system within 180 min, and the maximum concentration of •OH in the Fe(III)/GA/H2O2 system was 4.6 times that in the Fe(III)/H2O2 system. A series of the important variables were optimized in detail, including solution pH, GA dosage, amount of Fe(III) and H2O2. These findings provide compelling evidence for the non-negligible role of GA in the processes of organic pollutants degradation based on the Fe(III)/Fe(II) cycles and radicals generation in the Fenton-like system.
The effective separation and transport of photoinduced electron–hole pairs in photoanodes is of great significance to photoelectrochemical and catalytic performance. Here, a facile and effective ...two-step strategy is developed to fabricate double-shelled ZnO/CdS/CdSe porous nanotube photoanodes from ZnO nanorod arrays (NRAs). Surprisingly, after the process of the deposition of CdS and CdSe, the ZnO nanorod arrays are partially dissolved, resulting in the formation of ZnO/CdS/CdSe porous nanotube arrays (NTAs). By virtue of their unique porous nanotube structure and cosensitization effect, the ZnO/CdS/CdSe porous NTAs show superior photoelectrochemical water-splitting performance and organic-pollutant-degradation ability under visible light irradiation, as well as excellent long-term photostability.
