Construction of TiO2/Ag3PO4 nanojunctions on carbon fiber cloth for photocatalytically removing various organic pollutants in static or flowing wastewater

Preparation of MWCNT/CoMn2O4 nanocomposite for effectual degradation of picric acid via peroxymonosulfate activation

In recent years, using nanomaterials based on multi-wall carbon nanotubes (MWCNT) through the activation of peroxymonosulfate (PMS) has attracted more attention to the degradation of organic pollutants. This research presented a new route for the synthesis of MWCNT/CoMn2O4 nanocomposite for the degradation of picric acid using advanced oxidation processes (AOPs). Firstly, CoMn2O4 nanoparticles were prepared and then loaded on MWCNT using ultrasonic waves. The results of various analyzes confirmed the successful loading of nanoparticles on carbon nanotubes. As the degradation process proceeds through oxidation processes, the high electronic conductivity of MWCNT and the active sites of Mn and Co in the nanocomposite play an essential role in activating PMS to generate reactive oxygen species (ROS). An investigation of the reaction mechanism in different conditions showed that the highest speed of picric acid decomposition in the presence of nanocomposite (98%) was in 47 min. However, the scavenger test showed that HO· and SO4·- radicals are more important in the degradation process. Meanwhile, the results showed that removing picric acid using MWCNT/CoMn2O4 was more effective than CoMn2O4 alone and confirmed the interaction effect of MWCNT nanotubes with AB2O4 nanocatalyst.

Progressive Insights into Metal-Organic Frameworks and Metal-Organic Framework-Membrane Composite Systems for Wastewater Management

The sustainable management of wastewater through recycling and utilization stands as a pressing concern in the trajectory of societal advancement. Prioritizing the elimination of diverse organic contaminants is paramount in wastewater treatment, garnering significant attention from researchers worldwide. Emerging metal-organic framework materials (MOFs), bridging organic and inorganic attributes, have surfaced as novel adsorbents, showcasing pivotal potential in wastewater remediation. Nevertheless, challenges like limited water stability, elevated dissolution rates, and inadequate hydrophobicity persist in the context of wastewater treatment. To enhance the performance of MOFs, they can be modified through chemical or physical methods, and combined with membrane materials as additives to create membrane composite materials. These membrane composites, derived from MOFs, exhibit remarkable characteristics including enhanced porosity, adjustable pore dimensions, superior permeability, optimal conductivity, and robust water stability. Their ability to effectively sequester organic compounds has spurred significant research in this field. This paper introduces methods for enhancing the performance of MOFs and explores their potential applications in water treatment. It delves into the detailed design, synthesis strategies, and fabrication of composite membranes using MOFs. Furthermore, it focuses on the application prospects, challenges, and opportunities associated with MOF composite membranes in water treatment.

Simultaneous photocatalytic degradation and SERS detection of tetracycline with self-sustainable and recyclable ternary PI/TiO2/Ag flexible microfibers

Facile and efficient photocatalysts using sunlight, as well as fast and sensitive surface-enhanced Raman spectroscopy (SERS) substrates, are urgently needed for practical degradation of tetracycline (TC). To meet these requirements, a new paradigm for PI/TiO2/Ag organic‒inorganic ternary flexible microfibers based on semiconducting titanium dioxide (TiO2), the noble metal silver (Ag) and the conjugated polymer polyimide (PI) was developed by engineering a simple method. Under sunlight, the photocatalytic characteristics of the PI/TiO2/Ag flexible microfibers containing varying amounts of Ag quantum dots (QDs) were evaluated with photocatalytic degradation of TC in aqueous solution. The results demonstrated that the amount of Ag affected the photocatalytic activity. Among the tested samples, PI/TiO2/Ag-0.07 (93.1%) exhibited a higher photocatalytic degradation rate than PI/TiO2 (25.7%), PI/TiO2/Ag-0.05 (77.7%), and PI/TiO2/Ag-0.09 (63.3%). This observation and evaluation conducted in the present work strongly indicated a charge transfer mechanism. Moreover, the PI/TiO2/Ag-0.07 flexible microfibers exhibited highly sensitive SERS detection, as demonstrated by the observation of the Raman peaks for TC even at an extremely low concentration of 10-10 moles per liter. The excellent photocatalytic performance and SERS detection capability of the PI/TiO2/Ag flexible microfibers arose from the Schottky barrier formed between Ag and TiO2 and also from the outstanding plasmonic resonance and visible light absorptivity of Ag, along with immobilization by the PI. The successful synthesis of PI/TiO2/Ag flexible microfibers holds significant promise for sensitive detection and efficient photocatalytic degradation of antibiotics.

Improved photocatalytic property of lignin-derived carbon nanofibers through catalyst synergy

Converting lignin into high value-added products is essential to reduce our dependence on petroleum resources and protect our environment. In this work, TiO₂ and g-C₃N₄ are loaded in the lignin-derived carbon nanofibers (LCNFs) and an efficient LCNFs-based photocatalytic material (TiO₂/g-C₃N₄@LCNFs) is developed. The spinnability of lignin solution, the chemical structure and morphology of the LCNFs, and the catalytic degradation property of the TiO₂/g-C₃N₄@LCNFs for Rhodamine B (RhB) are systematically investigated. The TiO₂/g-C₃N₄@LCNFs achieve a 92.76 % degradation rate of RhB under UV-vis irradiation, which is close to or higher than most reported carbon fiber-based photocatalysts. The excellent degradation property of the photocatalysts can be ascribed to the synergy of TiO₂ and g-C₃N₄, which improves the excitation efficiency of electron and hole, and prolongs the lifetime of electron-hole pairs. We envision that our work will provide some guidance for the development of efficient photocatalysts based on biomass-derived fiber materials.

Recycling Carbon Fiber from Carbon Fiber-Reinforced Polymer and Its Reuse in Photocatalysis: A Review

Driven by various environmental and economic factors, it is emerging to adopt an efficient and sustainable strategy to recycle carbon fibers (rCFs) from carbon fiber-reinforced polymer (CFRP) wastes and reuse them in high-value applications. This review summarized the latest progress of CFRP waste recycling methods (including mechanical, chemical, and thermal methods), discussed their advantages and disadvantages, influence parameters and possible environmental effects, and their potential effects on the mechanical and surface chemical properties of rCFs. In addition, the latest optimization schemes of leading recycling technologies were detailed. According to the literature, CFs are the key points in the structural support of semiconductor-based recyclable photocatalytic systems and the enhancement of performance, which means that rCFs have high reuse potential in sustainable photocatalysis. Therefore, this paper also emphasized the possibility and potential value of reusing recovered fibers for developing recyclable photocatalytic products, which may be a new way of reuse in environmental purification often ignored by researchers and decision-makers in the field of CFs.

Photocatalytic Degradation of Tetracycline by Supramolecular Materials Constructed with Organic Cations and Silver Iodide

Photocatalytic degradation, as a very significant advanced oxidation technology in the field of environmental purification, has attracted extensive attention in recent years. The design and synthesis of catalysts with high-intensity photocatalytic properties have been the focus of many researchers in recent years. In this contribution, two new supramolecular materials {[(L1)·(Ag4I7)]CH3CN} (1), {[(L2)·(Ag4I7)]CH3CN} (2) were synthesized by solution volatilization reaction of two cationic templates 1,3,5-Tris(4-aminopyridinylmethyl)-2,4,6-Trimethylphenyl bromide (L1) and 1,3,5-Tris(4-methyl pyridinyl methyl)-2,4,6-trimethylphenyl bromide (L2) with metal salt AgI at room temperature, respectively. The degradation effect of 1 and 2 as catalyst on tetracycline (TC) under visible light irradiation was studied. The results showed that the degradation of TC by 1 was better than that by 2 and both of them had good stability and cyclability. The effects of pH value, catalyst dosage, and anion in water on the photocatalytic performance were also investigated. The adsorption kinetics fit the quasi-first-order model best. After 180 min of irradiation with 1, the degradation rate of TC can reach 97.91%. In addition, the trapping experiments showed that ·OH was the main active substance in the photocatalytic degradation of TC compared with ·O2− and h+. Because of its simple synthesis and high removal efficiency, catalyst 1 has potential value for the treatment of wastewater containing organic matter.

Ag3PO4-Deposited TiO2@Ti3C2 Petals for Highly Efficient Photodecomposition of Various Organic Dyes under Solar Light

Two-dimensional Ti₃C₂ MXenes can be used to fabricate hierarchical TiO₂ nanostructures that are potential photocatalysts. In this study, the photodecomposition of organic dyes under solar light was investigated using flower-like TiO₂@Ti₃C₂, deposited using narrow bandgap Ag₃PO₄. The surface morphology, crystalline structure, surface states, and optical bandgap properties were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption analysis, and UV-Vis diffuse reflectance spectroscopy (UV-DRS). Overall, Ag₃PO₄-deposited TiO₂@Ti₃C₂, referred to as Ag₃PO₄/TiO₂@Ti₃C₂, demonstrated the best photocatalytic performance among the as-prepared samples, including TiO₂@Ti₃C₂, pristine Ag₃PO₄, and Ag₃PO₄/TiO₂ P25. Organic dyes, such as rhodamine B (RhB), methylene blue (MB), crystal violet (CV), and methylene orange (MO), were efficiently degraded by Ag₃PO₄/TiO₂@Ti₃C₂. The significant enhancement of photocatalysis by solar light irradiation was attributed to the efficient deposition of Ag₃PO₄ nanoparticles on flower-like TiO₂@Ti₃C₂ with the efficient separation of photogenerated e-/h+ pairs, high surface area, and extended visible-light absorption. Additionally, the small size of Ag₃PO₄ deposition (ca. 4–10 nm diameter) reduces the distance between the core and the surface of the composite, which inhibits the recombination of photogenerated charge carriers. Free radical trapping tests were performed, and a photocatalytic mechanism was proposed to explain the synergistic photocatalysis of Ag₃PO₄/TiO₂@Ti₃C₂ under solar light.

Ag Nanoparticles Decorated ZnO Nanorods as Multifunctional SERS Substrates for Ultrasensitive Detection and Catalytic Degradation of Rhodamine B

Industrial wastewater containing large amounts of organic pollutants is a severe threat to the environment and human health. Thus, the rapid detection and removal of these pollutants from wastewater are essential to protect public health and the ecological environment. In this study, a multifunctional and reusable surface-enhanced Raman scattering (SERS) substrate by growing Ag nanoparticles (NPs) on ZnO nanorods (NRs) was produced for detecting and degrading Rhodamine B (RhB) dye. The ZnO/Ag substrate exhibited excellent sensitivity, and the limit of detection (LOD) for RhB was as low as 10⁻¹¹ M. Furthermore, the SERS substrate could efficiently degrade RhB, with a degradation efficiency of nearly 100% within 150 min. Moreover, it retained good SERS activity after multiple repeated uses. The interaction between Ag NPs, ZnO, and RhB was further investigated, and the mechanism of SERS and photocatalysis was proposed. The as-prepared ZnO/Ag composite structure could be highly applicable as a multifunctional SERS substrate for the rapid detection and photocatalytic degradation of trace amounts of organic pollutants in water.

A Mini-Review on Preparation of Functional Composite Fibers and Their Based Devices

Composite fibers are composed of two or more different components by functionating, coating or direct spinning, enabling unique characteristics, such as design ability, high strength, and high- and low-temperature resistance. Due to their ability to be directly woven into or stitched onto textiles to prepare flexible electronic devices, stretchable composite fibers have drawn great attention, enabling better wearability and integrality to wearable devices. Fiber or fiber-based electronic film or textiles represent a significant component in wearable technology, providing the possibility for portable and wearable electronics in the future. Herein, we introduce the composite fiber together with its preparation and devices. With the advancement of preparation technology, the as-prepared composite fibers exhibit good performance in various applications closely related to human life. Moreover, a simple discussion will be provided based on recent basic and advanced progress on composite fibers used in various devices.

Bismuth oxybromide/bismuth oxyiodide nanojunctions decorated on flexible carbon fiber cloth as easily recyclable photocatalyst for removing various pollutants from wastewater

Various semiconductor powders (such as bismuth oxybromide/bismuth oxyiodide (BiOBr/BiOI) nanojunctions) can photodegrade wastewater efficiently, but their practical application is limited by poor recovery performance. To address the problem, we report the construction of BiOBr/BiOI nanojunctions on flexible carbon fiber cloth (CFC) substrate as an easily recycled photocatalyst by the dipping-solvothermal-dipping-solvothermal four-step method. CFC/BiOBr/BiOI is composed of CFC substate and two layers of nanosheets, while BiOBr nanosheets (thickness: 10-30 nm, diameter: 200-400 nm) were grown in the inner layer and BiOI nanosheets (thickness: 50-80 nm, diameter:300-600 nm) were grown in the outer layer. CFC/BiOBr/BiOI (4 × 4 cm²) can effectively photodegrade 97.7% acid orange 7 (AO7), 91.3% levofloxacin (LVFX) and 97.8% tetracycline (TC) within 120 min under the illumination of visible-light, better than CFC/BiOBr (73.2% AO7, 71.6% LVFX and 81.6% TC). Furthermore, superoxide radical (•O₂^-) and hydroxyl radical (•OH) are the main active substances during removing LVFX by CFC/BiOBr/BiOI. Besides, CFC/BiOBr/BiOI can efficiently reduce 93.5% chemical oxygen demand (COD) concentration of acrylic resin production wastewater (ARPW) under visible-light illumination for 3 h, better than CFC/BiOBr (36.6% COD). Therefore, CFC/BiOBr/BiOI has broad application prospects in purifying wastewater as a new type of easily recycled photocatalyst.

Fabrication of NH2-MIL-125(Ti) nanodots on carbon fiber/MoS2-based weavable photocatalysts for boosting the adsorption and photocatalytic performance

Metal-organic frameworks (MOFs) are prospective photocatalysts for removing pollutants. However, the large size of MOFs results in unsatisfactory photocatalytic performance, thus restricting their further usage. Herein, ultrasmall Ti MOF (NH₂-MIL-125(Ti)) nanodots (diameter: < 10 nm) were prepared on carbon fiber (CF) (diameter: ∼7 μm) based MoS₂ (thickness: ∼20 nm, length: ∼200 nm) via a facile method and used as an efficient and reusable photocatalyst. The weaved CF/MoS₂/NH₂-MIL-125(Ti) cloth (0.15 g, 4 × 4 cm²) shows good reusability with an easy reusing process. Compared with large size NH₂-MIL-125(Ti) based sample, our well-prepared NH₂-MIL-125(Ti) nanodots based sample shows the improved surface area (290.1 m² g^-1) and it can generate more reactive oxygen species (ROS), which enhance removal performance (81.1% levofloxacin (LVFX), 67.9% acid orange 7 (AO7), 94.3% methylene blue (MB) and 100% Cr(Ⅵ)) in 120 min. Additionally, the recycling test for 4 cycles indicates high stability. This work highlights the function of easy-recyclable NH₂-MIL-125(Ti) nanodots-based heterojunctions in wastewater purification.

Preparation of Ag3PO4/TiO2(B) Heterojunction Nanobelt with Extended Light Response and Enhanced Photocatalytic Performance

Photocatalytic degradation, as an emerging method to control environmental pollution, is considered one of the most promising environmental purification technologies. As Tibet is a region with some of the strongest solar radiation in China and even in the world, it is extremely rich in solar energy resources, which is ideal for applying photocatalytic technology to its ecological environment protection and governance. In this study, Na₂Ti₃O₇ nanobelts were prepared via a hydrothermal method and converted to TiO₂∙xH₂O ion exchange, which was followed by high-temperature calcination to prepare TiO₂(B) nanobelts (“B” in TiO₂(B) means “Bronze phase”). A simple in situ method was used to generate Ag₃PO₄ particles on the surface of the TiO₂ nanobelts to construct a Ag₃PO₄/TiO₂(B) heterojunction composite photocatalyst. By generating Ag₃PO₄ nanoparticles on the surface of the TiO₂(B) nanobelts to construct heterojunctions, the light absorption range of the photocatalyst was successfully extended from UV (ultraviolet) to the visible region. Furthermore, the recombination of photogenerated electron–hole pairs in the catalyst was inhibited by the construction of the heterojunctions, thus greatly enhancing its light quantum efficiency. Therefore, the prepared Ag₃PO₄/TiO₂(B) heterojunction composite photocatalyst greatly outperformed the TiO₂(B) nanobelt in terms of photocatalytic degradation.

The fabrication of flexible wearable electrodes based on a carbon nanotubes/nickel/nickelous hydroxide ternary composite by facile single-side printing technology

A new material design strategy is developed to prepare high-performance flexible electrochemical electrodes. Carbon nanotubes (CNTs) and nickel/nickelous hydroxide (Ni/Ni(OH)₂) are compounded through a chemical plating method and hydrothermal process. A single-side printing method is used to combine the active material and a flexible cotton substrate. The interfinger microstructure of the textile electrode can greatly facilitate charge/ion transfer at the electrode-electrolyte interface. One side of the fabric, which is untreated, could directly contact with human skin, providing a comfortable and user-friendly surface. With the CNTs/Ni/Ni(OH)₂ ternary composite as a positive electrode and CNTs as a negative electrode, we assembled an in-plane asymmetrical micro-supercapacitor device (SF-NPCs). Thanks to a synergistic effect, SF-NPCs displays a high energy density of 0.29 W h cm^-2 at a power density of 7.2 W cm^-2. The operating window is extended to 1.5 V, and the device displays good potential for applications in the field of smart textiles.

Decoration of amine functionalized zirconium metal organic framework/silver iodide heterojunction on carbon fiber cloth as a filter- membrane-shaped photocatalyst for degrading antibiotics

The development of recyclable photocatalyst with high adsorption and excellent photocatalytic performance has attracted considerable attention. Herein, we report a three-component photocatalyst by constructing porous amine functionalized zirconium metal organic framework (UiO-66-NH₂) and broad photo-responsive AgI on flexible carbon fiber cloth (CFC). UiO-66-NH₂ nanoparticles (200-400 nm) were in-situ grown on the surface of CFC (16.5 ± 0.5 μm, 4 × 4 cm²) by a solvothermal route, then AgI particles (50-100 nm) were synthesized on CFC/UiO-66-NH₂ via a modified chemical bath deposition method. The obtained CFC/UiO-66-NH₂/AgI can effectively adsorb 19.0% levofloxacin (LVFX) or 18.4% ciprofloxacin (CIP) in 60 min in the dark and degrade 84.5% LVFX or 79.6% CIP in 120 min under visible light irradiation. Furthermore, the filter-membrane-shaped CFC/UiO-66-NH₂/AgI can be utilized to treat the flowing sewage (CIP, 10 mg/L, ~1 L/h), and the removing efficiency of CIP reached 71.0% after 10 grades. Therefore, this work demonstrates the huge application prospect of recyclable CFC/UiO-66-NH₂/AgI with high adsorption and photocatalytic capacity in flowing sewage treatment under visible light illumination.

Ionic Liquid-Assisted Synthesis of Ag3PO4 Spheres for Boosting Photodegradation Activity under Visible Light

In this work, a simple chemical precipitation method was employed to prepare spherical-like Ag3PO4 material (IL-Ag3PO4) with exposed {111} facet in the presence of reactive ionic liquid 1-butyl-3-methylimidazole dihydrogen phosphate ([Omim]H2PO4). The crystal structure, microstructure, optical properties, and visible-light photocatalytic performance of as-prepared materials were studied in detail. The addition of ionic liquids played a crucial role in forming spherical-like morphology of IL-Ag3PO4 sample. Compared with traditional Ag3PO4 material, the intensity ratio of {222}/{200} facets in XRD pattern of IL-Ag3PO4 was significantly enhanced, indicating the main {111} facets exposed on the surface of IL-Ag3PO4 sample. The presence of exposed {111} facet was advantageous for facilitating the charge carrier transfer and separation. The light-harvesting capacity of IL-Ag3PO4 was larger than that of Ag3PO4. The photocatalytic activity of samples was evaluated by degrading rhodamine B (RhB) and p-chlorophenol (4-CP) under visible light. The photodegradation efficiencies of IL-Ag3PO4 were 1.94 and 2.45 times higher than that of Ag3PO4 for RhB and 4-CP removal, respectively, attributing to a synergy from the exposed {111} facet and enhanced photoabsorption. Based on active species capturing experiments, holes (h+), and superoxide radical (•O2−) were the main active species for visible-light-driven RhB photodegradation. This study will provide a promising prospect for designing and synthesizing ionic liquid-assisted photocatalysts with a high efficiency.

Visible-light-driven photocatalytic degradation of RhB by carbon-quantum-dot-modified g-C3N4 on carbon cloth

Highly efficient semiconductor photocatalysis technology is widely used for water purification.

Anatase versus Triphasic TiO2: Near-identical synthesis and comparative structure-sensitive photocatalytic degradation of methylene blue and 4-chlorophenol

Studies on photocatalytic activity of monophasic and biphasic TiO₂ have been well explored. However, detailed studies on the photocatalytic activity of triphasic titania, as opposed to monophasic or biphasic TiO₂ are scarce. Here we report a comparative structure-sensitive photocatalytic study of triphasic versus anatase TiO₂, both have been synthesized under near-identical conditions through a customized sol-gel approach. The composition of the phases is tuned just by varying the thermal pre-treatment conditions of TiO₂ gel that has been subsequently subjected to calcination at 300 °C. Interestingly, when the pre-treatment temperature of the gel is systematically increased from 50 to 250 °C, a transition from anatase to triphasic (anatase, rutile, and brookite) and then again to anatase has been observed. The synthesized TiO₂ phase compositions have been thoroughly characterized for their structural, optical, electrical, surface and morphological properties. Among the different phase compositions, triphasic titania having a significant proportion of rutile has been found to exhibit the highest photocatalytic activity, as probed using model organic pollutants, Methylene Blue (MB) and 4-Chlorophenol (4-CP). In addition to the earlier known factors such as effective heterojunction, and favorable position of the valence band (VB), an important contribution to the high photocatalytic activity of triphasic TiO₂ has been experimentally found to stem from the additional electron density in VB that is attributed to the lattice contraction of anatase phase owing to the coexistence of other two phases. The study provides fundamental insights into the energetics that impact the photocatalytic activity of triphasic versus anatase TiO₂.

K, Na and Cl co-doped TiO2 nanorod arrays on carbon cloth for efficient photocatalytic degradation of formaldehyde under UV/visible LED irradiation

A photocatalytic reactor of TiO₂ nanorod arrays on carbon cloth for gaseous formaldehyde degradation.

Synthesis of TiO2–Ag3PO4 photocatalyst material with high adsorption capacity and photocatalytic activity: application in the removal of dyes and pesticides

The photocatalytic activity of TiO₂ can be enhanced by coupling it with other semiconductors and the semiconductor composites may find useful application in water treatment technologies. TiO₂–Ag₃PO₄ composites were synthesized and characterized with XRD, SEM-EDX and DRS. The synthesized TiO₂–Ag₃PO₄ showed high photocatalytic activity in the presence UV-vis light on rhodamine B, methylene blue and the pesticides imidacloprid, atrazine and pyrimethanil. LC-MS analysis of the photodegraded pyrimethanil led to the identification of hydroxylated and aliphatic derivatives of pyrimethanil. The photocatalytic activity of the coupled semiconductor was higher than that of the bare TiO₂ and Ag₃PO₄ and this was attributed to the unique band matching between TiO₂ and Ag₃PO₄ which resulted in efficient charge separation and subsequent reduction in the electron–hole recombination. In addition, the synthesized TiO₂–Ag₃PO₄ showed strong adsorption for water soluble dyes implying that TiO₂–Ag₃PO₄ can remove pollutants through photocatalysis and adsorption. The results from the study showed the potential application of TiO₂–Ag₃PO₄ composite in water treatment technologies.

Synthesis scheme of the Ag₃PO₄–TiO₂ nanocomposite.

Crystalline phase regulation of anatase-rutile TiO2 for the enhancement of photocatalytic activity

Biphasic TiO₂ with adjustable crystalline phases was prepared by the hydrothermal-calcination method assisted by nitric acid (HNO₃) and hydrogen peroxide (H₂O₂), using potassium titanate oxalate (K₂TiO(C₂O₄)₂) as the titanium source. The influences of H₂O₂ volume on anatase and rutile contents and photocatalytic activity of biphasic TiO₂ were investigated and the photocatalytic mechanism was explored. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and specific surface area (BET) were employed to characterize crystal structure, physical morphology, absorbable light, chemical composition, specific surface area and pore size distribution. The photocatalytic degradation efficiency towards a methylene blue (MB) solution under xenon light was tested, and the photocatalytic stability of the sample was investigated by photocatalytic cycle experiments. The prepared biphasic TiO₂ was nanorod-shaped and had a large specific surface area. The results showed the anatase TiO₂ content increased and the photocatalytic efficiency was enhanced as the H₂O₂ volume solution increased. Among the catalysts, the biphasic TiO₂ prepared with 30 mL of H₂O₂ had the best photocatalytic effect and could entirely degrade the MB solution after 30 minutes under irradiation. After three repeated degradations, the photocatalytic degradation rate was still estimated to be as high as 95%. It is expected that the work will provide new insights into fabricating heterophase junctions of TiO₂ for environmental remediation.

Biphasic TiO₂ with adjustable crystalline phases was prepared by the hydrothermal-calcination method assisted by nitric acid (HNO₃) and hydrogen peroxide (H₂O₂), using potassium titanate oxalate (K₂TiO(C₂O₄)₂) as the titanium source.

BiOBr/Ag/AgBr heterojunctions decorated carbon fiber cloth with broad-spectral photoresponse as filter-membrane-shaped photocatalyst for the efficient purification of flowing wastewater

The development of recyclable photocatalysts with broad-spectral photoresponse has drawn much attention for the practical application in flowing wastewater treatment. Herein, we have reported the construction of BiOBr/Ag/AgBr junctions on carbon fiber cloth (CFC) as broad-spectral-response filter-membrane-shaped photocatalyst that is efficient and easily recyclable. With CFC as the substrate, BiOBr nanosheets (diameter: 0.5-1 μm) were firstly synthesized by a hydrothermal method, and then Ag/AgBr nanoparticles (size: 100-300 nm) were prepared on the surface of CFC/BiOBr by using a chemical bath deposition route. CFC/BiOBr/Ag/AgBr presents superior flexibility and wide UV-Vis-NIR photoabsorption (from 200 to 1000 nm). Under visible light irradiation, CFC/BiOBr/Ag/AgBr (area: 4 × 4 cm²) can remove 99.8% rhodamine B (RhB), 99.0% acid orange 7 (AO7), and 93.0% tetracycline (TC) after 120 min, better than CFC/BiOBr (95.4% RhB, 55.0% AO7 and 91.2% TC). Interestingly, when CFC/BiOBr/Ag/AgBr is served as a filter-membrane in a photoreactor to purify the flowing sewage (RhB, rate: ~1.5 L h^-1), the degradation rate of RhB goes up to 90.0% after ten filtering grades. Therefore, CFC/BiOBr/Ag/AgBr has great potential to purify the flowing wastewater as a novel filter-membrane-shaped photocatalyst.

Fabrication of Ag3PO4/TiO2@molecular sieve (MS) ternary composites with remarkably enhanced visible light-responded photocatalytic activity and mechanism insight

In this study, Ag₃PO₄/TiO₂@molecular sieve (MS) ternary composites were fabricated via in-situ deposition and hydrothermal growth method for photocatalytic degradation of formaldehyde and sodium isobutyl xanthate (SIBX) under visible light irradiation. XRD, PL, UV-vis, UPS, SEM-EDS and XPS techniques were adopted to characterize the composite. The results show that the MS material was indexed as zeolite P and Ag₃PO₄-TiO₂ hybrid structure could improve the absorption of visible light and greatly inhibit the recombination of photogenerated charge carriers by introducing 3 times TiO₂. After evaluating the photocatalytic activity and kinetics model, it is found that photocatalytic activity is consistent with the apparent first-order kinetic model. The Ag₃PO₄/TiO₂-3@MS ternary composite under visible light irradiation appears the highest removal rate with 97.9% of formaldehyde and 96.7% of SIBX, respectively. Furthermore, the reusability of the photocatalyst was investigated by successive reuse. After five reuses, the removal rates reached 97.3% and 94.6% within 105 min for formaldehyde and SIBX, respectively. At last, the proposed mechanism of the photocatalytic reaction and the degradation routes of formaldehyde and SIBX were systematically discussed.

Synthesis of BiOBr/Ag3PO4 heterojunctions on carbon-fiber cloth as filter-membrane-shaped photocatalyst for treating the flowing antibiotic wastewater

Numerous nanosized photocatalysts have been demonstrated to treat antibiotic solutions efficiently in beakers, but plenty of antibiotics have been discharged to the flowing rivers. For photocatalytically degrading the flowing antibiotic wastewater, the prerequisite is to develop flexible large-scale filter-membrane with high photocatalytic activity. To solve this issue, with carbon fiber (CF) cloth as a flexible porous substrate, herein we have reported the in-situ growth of BiOBr/Ag₃PO₄ heterostructures. BiOBr nanosheets (thickness: ~10 nm, diameter: 0.5-1 μm) and Ag₃PO₄ particles (size: 50-200 nm) are synthesized on CF cloth successively via a solvothermal-chemical deposition two-step strategy. CF/BiOBr/Ag₃PO₄ cloth displays excellent visible photoabsorption (edge: ~520 nm). Under visible-light illumination, CF/BiOBr/Ag₃PO₄ cloth (4 × 4 cm²) could degrade ~90.0% tetracycline hydrochloride (TCH) as a model of antibiotics in 30 min in a beaker. Especially, CF/BiOBr/Ag₃PO₄ cloth can be used as the filter-membrane to construct multiple photocatalytic-setup for degrading the flowing antibiotic wastewater. The removal efficiency of TCH goes up from 12.8% at the first grade to 89.6% at the sixth grade. Furthermore, the photocatalytic mechanism of CF/BiOBr/Ag₃PO₄ cloth and the possible decomposition pathway of TCH have been proposed based on simulation and experiment results. Therefore, the present work provides some insight for developing flexible filter-membrane-shaped photocatalysts for degrading the flowing wastewater.