Degradation Rate Of Methylene Blue Research Articles

Bifunctional nanocomposites formed from magnetic lignin-derived carbon and molybdenum disulfide for efficient pollutant removal

The development of inexpensive and robust bifunctional nanocomposites toward efficient pollutant removal is crucial for wastewater remediation. Herein, we report a novel strategy for fabrication of magnetic nanocomposites loaded with molybdenum disulfide (Fe3O4/PLC-MoS2) using lignin biomacromolecules for efficient pollutant removal. The Fe3O4/PLC-MoS2 exhibit excellent pollutant removal capacity: The adsorption capacity of Pb(II) achieve 236.1 mg/g and the methylene blue (MB) degradation rate is up to 90.0 % within 20 min. The adsorption mechanism reveal that the enhanced removal properties is due to that the S atoms on the loaded MoS2 could convert into soluble sulfide and react with Pb(II) to form white precipitate β-Pb3O2SO4. Moreover, the experiments results demonstrate that the Fe3O4/PLC-MoS2 has a low bandgap, which can activate PMS to produce reactive oxygen species and degrade MB molecules efficiently. Notably, the Fe3O4/PLC-MoS2 demonstrate continued outstanding wastewater remediation capabilities even in scenarios where Pb(II) and MB coexisted. Overall, this study offers a viable and eco-friendly design of dual function removal material by using lignin waste toward promising implications for wastewater treatment.

Enhanced efficiency of AgAlO2/g-C3N4 binary composite to degrade organic pollutants for environmental remediation under visible light irradiation

This study explores the utilization of semiconductor-based photocatalysts for environmental remediation through photocatalytic degradation, harnessing solar energy for effective treatment. The primary focus is on the application of photocatalytic technology for the degradation of 2-chlorophenol and methylene blue, critical pollutants requiring remediation. The research involves the synthesis of binary AgAlO2/g-C3N4 nanocomposites through an exchange ion method, subsequent calcination, and sonication. This process enhances the transfer of photogenerated electrons from AgAlO2 to g-C3N4, resulting in a significantly increased reductive electron charge on the surface of g-C3N4. The photocatalytic activity of the synthesized composites is comprehensively examined in the degradation of 2-chlorophenol and methylene blue through detailed crystallographic, electron-microscopy, photoemission spectroscopy, electrochemical, and spectroscopic characterizations. Among the various composites, AgAlO2/20% g-C3N4 emerges as the most active photocatalyst, achieving an impressive 98% degradation of methylene blue and 97% degradation of 2-chlorophenol under visible light. Notably, AgAlO2/20% g-C3N4 surpasses bare AgAlO2 and bare g-C3N4, exhibiting 1.66 times greater methylene blue degradation and constant rate (k) values of 20.17 × 10−3 min−1, 4.18 × 10−3 min−1 and 3.48 × 10−3 min−1, respectively. The heightened photocatalytic activity is attributed to the diminished recombination rate of electron-hole pairs. Scavenging evaluations confirm that O2•− and h+ are the primary photoactive species steering methylene blue photodegradation over AgAlO2/g-C3N4 in the visible region. These findings present new possibilities for the development of efficient binary photocatalysts for environmental remediation.

Construction of Phosphorus‐Doped g‐C3N4 Nanosheets and Activation of Sodium Percarbonate for Degradation of Organic Pollutants in Wastewater

AbstractA novel phosphorus‐doped graphitic carbon nitride nanosheets (PS‐CN) photocatalyst was prepared by thermal polycondensation and thermal stripping method, and its physicochemical properties were characterized. The results show that PS‐CN formed a thin sheet and multi‐cavity structure by thermal delamination that could enhance the surface area, light reception, and adsorption capacity. The prepared PS‐CN activated sodium percarbonate system (PS‐CN/SPC) was developed for the degradation of dyeing wastewater with methylene blue (MB) as the target pollutant and the degradation mechanism was analyzed. At room temperature (20 °C), the degradation rate of MB in PS‐CN/SPC system within 10 min (88.13 %) was three times that of pure g‐C3N4. In addition, the MB was completely degraded under visible light within 60 min. Moreover, PS‐CN exhibited excellent reusability that the degradation rates of MB have remained above 96 % in five consecutive cycles. The free radical quenching experiments showed that hole (h+), hydroxyl radical (•OH) and superoxide radical (•O2−) all participated in MB degradation, and •OH was the main active species. The PS‐CN/SPC system would provide a high‐value solution for the treatment of dye wastewater due to the low cost of raw materials, superior photocatalytic activity, simple synthesis method, and reusability of the catalyst.

Enhanced Fenton-like process over Z-scheme MoO3 surface decorated with Fe2O3 under visible light

Photocatalysts consisting of Z-scheme heterojunctions are commonly used in wastewater treatment due to their exceptional reactivity in photocatalysis and highly efficient visible-light utilization. In this work, Fe2O3-decorated MoO3 rods were synthesized through a two-step method and their photodegradation of methylene blue (MB) was evaluated. The Fe2O3/MoO3 rods were characterized by XRD, SEM, micro-Raman, XPS, UV–Vis DRS, and PL to investigate their structural, morphological, and optical properties. The results indicate that the photodegradation efficiency of Fe2O3/MoO3 improved through a reduction in the gap energy and persistence of a 1D hexagonal prism structure. The degradation rate of MB was enhanced from 31.7 to 91.5% after irradiation for 180 min owing to electron–hole separation and Fenton-like process. Formation of the OH radical is a key factor in the photodegradation reaction and with the addition of H2O2 the efficiency can further improve via a Fenton-like mechanism. Furthermore, the Z-scheme mechanism concurrently delineated. The Fe2O3/MoO3 rod composites were also found to retain high photocatalytic efficiency after being reused five times, which may be useful for future applications.

Dimensionally integrated nanoarchitectonics with Cu nanoparticles embedded in g-C3N4 nanosheets for efficient photocatalytic hydrogen generation and dye degradation

High-efficiency and sustainable non-noble metal cocatalyst can reduce the reaction barrier of photocatalysis or electrocatalysis to promote the hydrogen evolution reaction, which provides a feasible method for large-scale hydrogen production. A one-step thermal polymerization method was developed to successfully incorporate copper (Cu) into graphite nitride carbon (g-C3N4) through a mechanochemical pre-treatment and subsequently thermal polymerization. The synthesis controlling is a key to arrange the distribution of Cu nanoparticles in g-C3N4 nanosheets. Photocatalytic hydrogen generation tests were carried out for Cu incorporated g-C3N4 nanosheets obtained at different temperatures. Cu incorporated g-C3N4 at 680 °C (CCN-680) revealed the best H2 generation rate of 2985 μmol g-1 h−1, which was 12.7 times of that of pure g-C3N4 nanosheets obtained at same temperature. Furthermore, the degradation of methylene blue (MB) indicated that sample CCN-680-3 with optimized Cu ratio revealed enhanced performance, in which the degradation rate of MB increased from 80 to 97 % within 60 min. The introduction of Cu narrowed the band gap of g-C3N4 nanosheets, expanded light response in visible region, and finally improved greatly the separation efficiency of photogenerated charge carriers. These results are significant for highly efficient and stable photocatalysts.

Construction of TiO2 on cotton straw deposited on g-C3N4 heterojunction to improve the photocatalytic degradation activity of methylene blue and tetracycline

In this study, agricultural waste cotton stalk was used as biomass carbon source, calcined with TiO2 at a high temperature, deposited in a TiO2 lattice, and used as an electron acceptor to inhibit photogenerated electron recombination. Subsequently, it underwent secondary calcination with g-C3N4 to form a C-TiO2/g-C3N4 composite catalyst. Experimental results showed that the coupling of carbon-doped TiO2 and g-C3N4 accelerated photogenerated electron–hole pairs pair migration, effectively inhibited the recombination of photogenerated carriers, and thus improved the removal efficiency of methylene blue (MB) and tetracycline hydrochloride (TC). Upon irradiation with a 500 W xenon lamp, the degradation rates of MB and TC achieved were 92.6 % and 95.3 % in 90 min, respectively.

Low-temperature compositing of graphene to nanodiamonds by thermal reduction of graphene oxide and photocatalytic properties

Graphene has become a research hotspot in the field of composites due to its special structure and excellent properties The common preparation methods of graphene matrix composites include solvent (hydrothermal) method, sol-gel method, chemical reduction method, electrochemical deposition method, etc. Nanodiamond/reduced graphite oxide (rGO) composites are directly synthesized by low-temperature heat treatment with nanodiamonds and graphite oxide (GO) powders as raw materials with the aid of GO thermal reduction at 195 °C. The degradation ability of samples to methylene blue (MB) under simulated sunlight was tested. Results indicated that GO was thermally reduced to graphene at low temperature, and rGO well combined with diamond. After the introduction of GO, the lattice of nanodiamond underwent distortion. Diamond and graphene formed a quasi-core–shell structure, and the interface between them was well bonded. The composite had a large specific surface area (Brunauer–Emmett–Teller value of 93.13 m2/g). The addition of GO enhanced the absorbance of the samples and reduced the bandgap of nanodiamond. When the ratio of nanodiamond to GO was 6:1, the sample exhibited excellent sunlight photocatalytic activity, and MB degradation rate reached 99.8 % within 40 min. The reduction reaction of GO at low temperature promoted its rapid combination with nanodiamonds. This method had the outstanding advantages of simple process, environment friendliness, and easy mass production.

Biopolyphenol stabilized CoFe2O4-rGO/GO catalytic cleaning membrane for fast and high-efficiency contaminants removal

Utilizing membrane materials for the purification of wastewater represents an effective approach to address water scarcity. Nonetheless, the issues of membrane fouling and stability hinder their widespread application. Herein, an effective biopolyphenols (PP) modification strategy was proposed to construct strongly stable cobalt ferrite-loaded graphene oxide (CoFe2O4-rGO-PP/GO) membranes with catalytic cleaning function. Compared with the membranes without PP modification, the incorporation of polymerized tannic acid (pTA), green tea polyphenol (GTP), and black tea polyphenol (BTP) significantly improved membrane separation efficiencies of methylene blue (MB), with high removal reaching 99.11, 98.92, and 99.20 %, respectively. Notably, the CoFe2O4-rGO-pTA/GO membrane demonstrated high rejection and outstanding permeability of 167.2 L m−2 h−1 bar−1. Introducing pTA, GTP, and BTP could enhance MB degradation rate constants by 61.54, 38.46, and 19.23 % via peroxymonosulfate (PMS) activation, respectively. Remarkably, CoFe2O4-rGO-pTA/GO membrane achieved near-complete MB degradation within 12 min. Moreover, CoFe2O4-rGO-PP/GO membranes maintained high MB rejection exceeding 97 % even after ten cycles, highlighting exceptional stability and catalytic cleaning performance. The separation mechanism of these membranes was dominantly governed by the nano-confined adsorption under pressure-driven flow-through process, which was greatly distinguished from a size-sieving mechanism of densely stacked 2D lamellar membranes replying on their in-plane pores or interlayer nano/subnano-channels. This PP modification strategy can be extended to design diversified 2D lamellar membranes with guest intercalation, to achieve high stability, superior separation and multi-function.

An organic-inorganic hybrid based on bicapped Keggin polyoxometalate as a heterogeneous catalyst for MB removal via Fenton-like/photo-Fenton-like degradation or reduction

An organic-inorganic hybrid polyoxometalate (POM) [CuI(phen)2]4[PMoVI8VIV6O42{CuI(phen)}2]•H5O2 (CuPMoV) was explored as heterogeneous Fenton-like catalyst for methylene blue (MB) degradation in the absence/presence of visible light at neutral pH. CuPMoV was characterized by XRD, SEM, FT-IR and UV–vis DRS techniques. The effect of initial pH, the concentrations of H2O2 and dye, and CuPMoV dosage on the degradation was evaluated. The possible mechanism for the Fenton-like/photo-Fenton-like was proposed. Under the optimum conditions, the MB degradation rates were 85.3 % (Fenton-like reaction) and 95.2 % (photo-Fenton-like reaction) in 12 min, respectively. CuPMoV also exhibited excellent catalytic performance for MB reduction in the presence of NaBH4, with the reduction rate of 98.6 % in 90 s. The pseudo-first-order rate constant of the reduction was estimated as 0.0246 s−1. The high reusability and stability of CuPMoV enabled it to undergo five cycles of usage without significant loss of catalytic activity. The multi-metal composition of CuPMoV and the bicapped Keggin unit were the root of its excellent catalytic activities. CuPMoV may be a potential candidate for the practical treatment of MB contaminated wastewater via oxidation or reduction.

Fabrication and properties analysis of paraffin@TiO2/Ag phase change microcapsules for thermal energy storage and photocatalysis

To develop a material that can be applied in the field of thermoregulation materials for residential buildings and degradation of organic pollutants. A novel microencapsulated phase change material, paraffin@TiO2/Ag, was prepared using interfacial condensation technology. The paraffin@TiO2/Ag microcapsules' melting point and latent heat were 48.00 °C and 63.56 J/g, respectively, according to the DSC study results, and their encapsulation rate was 46.11 %. In addition, the experimental results of photocatalytic degradation of MB (methylene blue) showed that the paraffin@TiO2/Ag microcapsules had high photocatalytic activity for organic dyes under natural light, and the degradation rate of MB reached 99 % when the light exposure time reached 4 h. By comparing the reaction rate constant of MB by paraffin@TiO2 microcapsules (0.98969 h−1) with that of MB by paraffin@TiO2/Ag microcapsules (1.15845 h−1), it was learned that the introduction of Ag nanoparticles effectively improved the photocatalytic activity of the phase change microcapsules.

Structural Diversity Design, Four Nucleation Methods Growth and Mechanism of 3D Hollow Box TiO2 Nanocrystals with a Temperature-Controlled High (001) Crystal Facets Exposure Ratio.

Three-dimensional (3D) hollow box TiO2 nanocrystals with structural diversity have been designed and grown by four nucleation methods, including the acid dissolution denucleation method with Fe2O3 as heterogeneous nucleation, the topological phase transition method, the sonic solvothermal method, and the air atmosphere sintering method with TiOF2 as homogeneous nucleation. Through full morphology analysis and structural characterization, reasonable growth mechanisms of 3D hollow box TiO2 nanocrystals were proposed, including nucleation dissolution, Oswald ripening, and hydrolysis reactions. It was found that the high energy (001) crystal facets exposure ratio was closely correlated with reaction temperature of four nucleation-methods, which even reached 92% for the first time. Under simulated sunlight irradiation, their hydrogen production performance and photocatalytic degradation efficiency on model dye molecules rhodamine B (RhB) and methylene blue (MB) were evaluated, and as-prepared hollow box TiO2 nanocrystals prepared by the sonic solvothermal method exhibited the best photocatalytic performance, with a hydrogen production rate of 93.88 μmol/g/h. Within 70 min, the photocatalytic degradation rates of RhB and MB reached 96.59 and 75.25%, respectively, which were 5.74 and 5.54 times that of P25. Their properties are closely connected with the orderly cubic and hierarchy configuration structure of hollow box TiO2 nanocrystals, which have a high exposure ratio of (001) facet controlled by reaction temperatures, thereby greatly improving the photocatalytic activity. This study provides a classic reference for improving the properties of hollow box TiO2 nanocrystals through structural diversity design and various methods of nanocrystal growth.

Near-field electrospinning of PTFE/ZnO membrane with regular pore geometry and its photocatalytic performance

Poly(tetrafluoroethylene) (PTFE) membrane is remarkable due to its impressive comprehensive properties. However, the PTFE membrane’s chemical inertness and low surface energy make it difficult to achieve pore geometry regulation and functional modification. In this work, the PTFE/ZnO photocatalytic fiber membrane with regular membrane pore geometry was prepared by Near-filed electrospinning (NFES) technology. The precursor Zn(Ac)2 was added to the PTFE/poly(ethylene oxide) (PEO) spinning solution to introduce the ZnO seed layer. Then ZnO was grown in situ by hydrothermal method to prepare the NFES PTFE/ZnO membrane. The effects of the mass ratio of the PTFE/PEO spinning solution and the additional amount of Zn(Ac)2 on the membrane morphologies were investigated, and the effects of different membrane pore geometries on the photocatalytic degradation of methylene blue (MB) dye wastewater were discussed. The results showed that when the mass ratio of PTFE/PEO was 5:1 and the addition amount of Zn(Ac)2 was 15 wt%, the membrane had the optimal morphology. Compared with the PTFE/ZnO membrane prepared by electrospinning, the NFES PTFE/ZnO membrane with regular membrane pore geometry had more catalyst loading, and the dynamic MB removal rate reached 97.6% after 4 h of UV irradiation. After 5 cycles of testing, the degradation rate of MB can also reach 70.8%.

Preparation and photocatalytic properties of g-C3N4/WO3–SiO2 composite photocatalyst for methylene blue and methyl orange degradation

WO3–SiO2 gel was prepared by sol-gel method using ethyl orthosilicate and sodium tungstate dihydrate as raw materials, and a series of g-C3N4/WO3–SiO2 composite photocatalysts with different g-C3N4 loading loads were prepared on WO3–SiO2 gel. The photocatalytic degradation performance of methylene blue (MB) and methyl orange (MO) was investigated under 464 nm light source. According to the findings, the degrading effect of the g-C3N4/WO3–SiO2 composite catalyst is optimum when the load of g-C3N4 is 1.3 wt%, and the degradation rates of MB and MO are 95.62 % and 98.09 %, respectively. The characterization results show that the excellent photocatalytic performance is due to the formation of g-C3N4/WO3 heterojunction by the introduction of g-C3N4, which effectively promotes the migration and separation of photogenerated carriers, increases the number of active electrons and holes, and thus enhances its photocatalytic activity. In addition, according to the analysis of the energy band structure of the catalyst, the possible mechanism of g-C3N4/WO3–SiO2 degradation of MB (MO) is proposed as S-type heterojunction mechanism.

Magnetic-acoustic actuated spinous microrobot for enhanced degradation of organic pollutants

A growing interest in the development of efficient strategies for the removal of organic pollutants from polluted water is emerging. As such, artificial micro/nano machines performing excellent water purification tasks have recently attracted more research attention of scientists. Hereby a spinous Fe3O4@PPy microrobot is presented that towards an efficient organic pollutant removal by enhancing Fenton-like reaction. The microrobot is fabricated by wrapping polypyrrole (PPy) on a spiny magnetic template prepared from sunflowers pollen. Modulating the sound pressure and frequency of the ultrasonic field enables the Fe3O4@PPy microrobot to present multimode motion, such as violent eruption-like motion caused by local cavitation (ELM), march-like unific motion (MLM), and typhoon-like rotation toward the center gathered motion (TLM). This multimode motion achieves the sufficient locomotion of microrobots in three-dimensional space and effective contact with organic pollutants in polluted water. Furthermore, a 5.2-fold increase in the degradation rate of methylene blue has been realized using Fe3O4@PPy microrobots under low-concentration hydrogen peroxide conditions. Also, the magnetically controlled recovery of microrobots from water after the completion of the degradation task has been demonstrated. The magnetic-acoustic actuated spinous microrobot can be extrapolated to other catalytic microrobot, developing a new strategy for an easier implementation and recovery of microrobot in real applications of water purification.

Fabrication of iron doped titanium dioxide photocatalytic nanocomposite supported by water-quenched blast furnace slag and photocatalytic degradation of wastewater

Metallurgical solid waste blast furnace water quenched slag (WBFS) was employed as carrier materials to prepare Fe–TiO2/WBFS composite photocatalyst using a sol-gel method for improving both the photocatalytic activity and the high-value utilization of metallurgical solid waste. The Fe3+ doping technology was adopted to increase the utilization of solar energy. The influencing factors and photocatalytic activity were systematically evaluated by thermogravimetry/differential thermal analyser (TG-DSC), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) method, scanning electron microscopy-energy spectrometer (SEM-EDS), X-ray photoelectric spectroscopy (XPS), UV–Vis absorption spectrum and photoluminescence spectra technology through the degradation rate of methylene blue (MB) solution. The results showed that the Fe3+ ions were successfully incorporated into the TiO2 lattice, which had no effect on the crystalline phase of TiO2 and expanded the spectral response range of TiO2 from the ultraviolet region to the visible light region. When the calcination temperature was at 450 °C and the number of Fe–TiO2 sol loading cycles was two times, the photocatalytic activity of Fe–TiO2/WBFS presented the strongest, and the degradation ratio of MB reach the maximum value of 98.9 %. A uniform and dense anatase TiO2 thin film was wrapped on the surface of WBFS. The photocatalytic activity first improved and then weakened with an increase of calcination temperature, Fe3+ doping amounts and the loading cycles of sol. The TiO2 film changed from thin to thick and uneven to uniform, until cracking and spalling phenomenon finally occurred with an increase of Fe–TiO2 sol loading cycle from 1 to 3 times. When the Fe–TiO2/WBFS was reused for four times, the degradation rate of MB could still show 67.4 %, being far higher than that of TiO2/WBFS of 25.4 %.

Fabrication of direct Z-scheme heterojunction of S doped g-C3N4/Ag/AgI for efficient dye degradation

In this work, we scrutinized the photodegradation ability of a novel composite material, sulfur-doped graphitic carbon nitride/Ag/AgI (SCN/Ag/AgI) for methylene blue (MB) dye degradation. The SCN/Ag/AgI nanocomposite was fabricated by a cost-effective co-precipitation method. The fabricated SCN/Ag/AgI nanocomposite exhibited significantly enhanced photocatalytic activity i.e. 88% MB degradation rate. The SCN/Ag/AgI heterojunction followed a direct Z-scheme charge transferal channel in which Ag worked as an electron mediator. Furthermore, •OH and •O2– radicals reactive species were formed that efficiently destroyed MB pollutants.

One-Dimensional Shaving-like BiVO4 Nanobelts: Synthesis, Characterization and Photocatalytic Activity with Methylene Blue

One-dimensional shaving-like BiVO4 nanobelts were successfully synthesized via the oxide hydrothermal method (OHS), using V2O5 and Bi2O3 as raw materials and PEG 10000 (polyethylene glycol 10000) as a template. Multiple techniques, including XRD, SEM, TEM, HRTEM, UV–Vis, XPS, and photoelectrochemical measurements, were applied to characterize the obtained materials. The thickness of the BiVO4 nanobelt was approximately 10 nm, while the width was approximately 500 nm. EIS results showed that visible-light illumination caused the photogenerated charge of the BiVO4 nanobelts to have a faster transfer and a higher separation efficiency. Photocatalytic experiments indicated that with BiVO4 nanobelts as a catalyst, the degradation rate of MB (methylene blue) was close to 92.4%, and it disintegrated after two hours. Moreover, the pseudo-first-order kinetic model can be used to describe the photodecomposition reaction of MB catalysed by BiVO4 nanobelts. And this excellent photocatalytic activity of the shaving-like BiVO4 nanobelts may be related to their special morphology, narrow band gap (~2.19 eV), faster transfer and the separation efficiency of the photogenerated charge, leading to strong absorption in the visible region and improving the separation of the photogenerated electron–hole pairs. These novel monoclinic BiVO4 nanobelts exhibited great photocatalytic activity and are thus a promising candidate for application in visible-light-responsive photocatalysts.

Novel Pt/COF Janus micromotor with bowl-like structure as an effective catalyst in extremely acidic environments

To effectively enhance the catalytic activity and stability of the heterogeneous catalysts in extremely acidic environments, a novel Pt/COF Janus micromotor catalyst with bowl shape (BSJP) was prepared. The as-synthesized BSJP exhibited excellent catalytic degradation efficiency against methylene blue (MB) as the model substrate, owing to self-propelling motion caused by the unique bowl shape and the concentration effect of pollutants in the bowl-shaped structure. The catalyst has excellent catalytic efficiency. At circumneutral pH, the reaction rate constant of BSJP micromotor was 3.35 times of that of non-propellant particles. At pH = 2, Pt/COF-LZU1 BSJP exhibits the best activity with a maximum removal rate of 98.61 %. Moreover, even under extreme pH conditions (pH < 2), the catalytic degradation efficiency of MB remained high, and the structure and morphology of the catalyst remained unchanged. Importantly, the catalyst exhibited remarkable stability and recyclability. The degradation rate of MB and the removal rate of TOC remained above 90 % during the four cycles. This excellent catalytic performance under extremely acidic conditions was attributed to the physical confinement of Pt nanoparticles by stable COF-LZU1. This work confirms the broad application prospects of COF-carrier materials in water purification.

Efficient degradation of methylene blue by FeS2/MoS2 in heterogeneous Fenton-like process

Iron-based materials as Fenton catalysts exist the problems of low activation efficiency of hydrogen peroxide (H2O2) and narrow applicable pH range. Herein, we synthesized materials with different ratios of molybdenum to iron, named as MoS2/FeS2, and used them for the degradation of methylene blue (MB). Notably, the MB degradation rate of FeS2/MoS2/H2O2 system reached 99.9 % within 30 min under neutral conditions, and its degradation rate constant was 34.3 and 21.8 times than that of MoS2 alone and physical mixture of FeS2 + MoS2, respectively. The MB degradation rate was 81.4–99.9 % at solution pH of 3–11, suggesting that FeS2/MoS2 is applicable to the Fenton-like process at wide pH. The morphology and composition of materials were analyzed by X-ray diffraction (XRD), Barrett-Emmett-Teller (BET), Transmission electron microscopy (TEM) and Scanning electron microscope (SEM). The X-ray photoelectron spectroscopy (XPS) and experimental results showed that Mo and S accelerated Fe2+/Fe3+ cycling was the main reason for the enhancement of catalyst activity. The main reactive oxygen species (ROS) was singlet oxygen (1O2) in the system. After 4 applications of FeS2/MoS2, the MB degradation rate still reached more than 90 % within 30 min, which indicates the excellent stability of material. In summary, FeS2/MoS2 has promising prospects for the degradation of wastewater.

Evaluation of Au nanosphere content on ZnO nanoparticle surfaces as reusable and durable plasmonic nanocatalysts

AbstractBACKGROUNDAu/ZnO systems have been investigated in recent years as alternatives to improve the photocatalytic performance obtained by pure ZnO and other nanocatalysts based on ZnO nanostructures. ZnO nanoparticles and Au/ZnO nanocatalysts were successfully synthesized by facile and low‐cost methods, such hydrothermal synthesis and chemical reduction method, respectively. The plasmonic nanocatalysts were fabricated at different Au precursor (HAuCl4) concentrations (0.5–5 mM) to obtain different Au contents (0.31–13.9 at.%) on the ZnO surface. The influence of Au content on the ZnO surface and its photocatalytic activity was studied.RESULTSThe photocatalytic activities of pure ZnO and Au/ZnO nanocatalysts were evaluated in the photodegradation of methylene blue (MB) solution under UV light. The Au/ZnO nanocatalyst with the lowest Au content (0.31 at.%) showed the best photocatalytic performance, reaching an MB degradation rate of 99.99% within 60 min (an enhancement of 60% compared with ZnO nanoparticles) and a reaction rate constant of 4.186 min−1 (×10−2), which is higher than those of other novel and complex nanocatalysts based on ZnO. Moreover, five cycles of self‐cleaning and an outstanding durability of 25 aging months were obtained during photocatalytic applications.CONCLUSIONAs demonstrated, a high amount of Au nanospheres on the ZnO surface is not necessary to enhance its photocatalytic activity. This synthesis process offers the possibility of obtaining the optimum amount of Au loading over the ZnO surface to reach a better photocatalytic performance, good self‐cleaning ability, and outstanding durability in comparison with other complex and recently reported catalysts (composites based on ZnO nanostructures). © 2023 Society of Chemical Industry (SCI).