Photo-Fenton reaction is a more effective technique for pollutant disposal than photocatalytic reaction. Herein, Fe2O3@polypyrrole/Prussian blue (Fe2O3@PPy/PB) with a hierarchical porous structure ...was prepared by a reactive-template method. After transforming typical type-II Fe2O3@PPy to Z-scheme Fe2O3@PPy/PB via PB as a bridge, the degradation rate was increased by 1.4 times in photocatalytic reaction and 4.0 times in photo-Fenton reaction due to higher visible-light harvest, enhanced separation efficiency of photoinduced charges, lower interface resistance, and especially well-preserved redox potentials of holes and electrons. Mechanism studies revealed that holes were quenched by H2O2, and this led to •O2− generation and efficient separation of electrons. Meanwhile, O2 was reduced by separated electrons, and this further increased •O2− yield. Therefore, the main radicals changed from hole in photocatalytic reaction to •O2− in the photo-Fenton reaction, leading to an increase as high as 12.1-fold enhancement in the degradation rate. Conversely, only H2O2 participated into photocatalytic reaction using Fe2O3@PPy while O2 was absent, resulting in merely 4.2-fold improvement. This manuscript gives a comprehensive understanding on mechanisms of type-II and Z-scheme heterojunctions in both photocatalytic and photo-Fenton reactions. Obviously, the outcomes are beneficial for designing catalysts with high photo-Fenton activity.
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•Hierarchical porous Fe2O3@PPy/PB was prepared by a one-step reactive-template method.•Type-II Fe2O3@PPy was changed to Z-scheme Fe2O3@PPy/PB via PB as a bridge.•k in photo-Fenton reaction was 12.1 times higher than that of photocatalytic reaction.•k of Fe2O3@PPy/PB in photo-Fenton reaction was 4.0 times higher than that of Fe2O3@PPy.•Mechanisms of photocatalytic and photo-Fenton reactions were revealed.
Metal copper mesh with superhydrophobic and superoleophilic surface had been successfully fabricated via a facile solution−immersion process. The hierarchical structure was prepared on the commercial ...copper mesh surface by etching with the nitric acid. After being modified by 1-hexadecanethiol (HDT), the as-prepared mesh indicated both superhydrophobic and superoleophilic property simultaneously. This as-prepared metal mesh could then be applied for oil and water mixture separation. The unusual wettability of the as-prepared mesh was stable in corrosive conditions, such as acidic, basic, and salt solutions. The solution−immersion method was simple, time-saving, and inexpensive and therefore exhibited great potential application.
Environmental pollution caused by persistent organics has drawn intensive attention. Microwave-assisted Fenton reaction (MAFR) was a rapid and effective technique for their removal. Herein, a ...sponge-templated method was introduced for the scalable preparation of two-dimensional (2D) porous NiCo2O4 sheet. Its surface area was 4.0 times higher than that of NiCo2O4 aggregate prepared without a sponge template. Control experiments revealed that the hydrophilic surface and restricted growth effect of sponge were essential for shaping sheetlike morphology. According to the response surface methodology, the optimal condition in MAFR was 10 mg of catalyst, 10 mg of peroxymonosulfate, 300 W of microwave power, and 70 °C of temperature, under which 50 mg/L of rhodamine B (RhB) was degraded within 1.5 min. The degradation rate constant was as high as 0.45 min–1, which was about 2.0 times higher than the reaction catalyzed by NiCo2O4 aggregate. SO4 •– was identified as the main active species, as 62.2% of RhB removal was inhibited in their absence. The 2D porous NiCo2O4 sheet also exhibited good reusability and stability, Co3+ leaching in NiCo2O4 was only 1/14 that in Co3O4, and 81.7% of degradation efficiency was maintained even after five successive cycles.
The colloidal gold superparticle (SP)/polypyrrole (PPy) core/shell composites were successfully prepared by oxidative polymerization of pyrrole monomer on the surface of poly(N-vinylpyrrolidone) ...(PVP)-grafted colloidal gold SPs. These core/shell composites showed strong catalytic activity and excellent stability. Control experiments indicated that the morphology and the thickness of PPy shell were controllable by adjusting the dosage of pyrrole monomer. Meaningfully, the resulting SP/PPy core/shell composites were quite stable in water, which could be stored for more than half a year without damaging their structures. As an example, we demonstrated the use of these composites as catalyst for the reduction of methylene blue (MB) dye with a reducing agent of sodium borohydride. The composites exhibited highly catalytic activity and long-term stability, implying promising applications of SP/PPy composites in catalysis.
Silver/polypyrrole composites were coated on the surface of silica spheres to form raspberry-like composites. They displayed excellent catalytic properties in the reduction of methylene blue dye.
...Raspberry-like composites were prepared by coating the silver/polypyrrole core/shell composites onto the surface of silica spheres via oxidation polymerization of pyrrole monomer with Ag(NH
3)
2
+ ions as oxidants. The whole process allowed the absence of stabilizers, which greatly improved the quality of the conducting polymer composites. The morphology of the resulting composites was investigated, which can be described as raspberry-like; also, the structure and composition of the composites were characterized in detail. A possible formation mechanism was proposed. The present synthetic strategy substantially extended the scope of metal/conducting polymer composite synthesis. The raspberry-like composites exhibited excellent catalytic properties in the reduction of methylene blue dye with the reducing agent of sodium borohydride.
This article reports the facile synthesis of monodisperse polymer hollow spheres by seeded emulsion polymerization without additional treatment. In this method, P(St-MMA-MAA) copolymer latex ...particles were first prepared by emulsifier-free emulsion polymerization and then used as seeds to carry out emulsion polymerization of methyl methacrylate (MMA), divinyl benzene (DVB), and 2-hydroxyethyl methacrylate (HEMA) with potassium persulfate (KPS) as initiator at 80 °C. The void of hollow spheres was readily adjusted by changing the monomer/seed weight ratio, and it could be enlarged while the diameters of hollow spheres changed little after etching by dimethyl formamide (DMF). The effects of synthetic parameters including the monomer composition and the properties of seeds on the morphology of hollow spheres were investigated in detail. On the basis of the experimental results, it seemed reasonable to conclude that the formation of hollow spheres was due to the “dissolution” of seeds in monomers and phase separation between the constituent polymers. As a thermodynamic factor, sodium dodecyl sulfate (SDS) would allow the preparation of solid particles depending on its level.
Nanocomposites containing FeS as catalyst and MoS2 as cocatalyst have been synthesized toward efficient heterogeneous Fenton reaction. The deposition of FeS nanoparticles in situ on the surface of ...MoS2 nanosheets creates strong contact between the two components and generates a large number of exposed Mo6+ sites and sulfur vacancies, which contribute to the enhanced degradation rate by accelerating Fe3+/Fe2+ cycling and ensuring rapid electron transfer. In addition, the MoS2/FeS nanocomposite catalysts exhibit the best performance at near-neutral conditions (pH 6.5), which solves the challenges in conventional Fenton reactions such as leaching of metal ions, the formation of iron slurry, and the need of adjusting solution pH. Further, the nanocomposite can maintain high efficiency after many recycling experiments. It is believed that the MoS2/FeS nanocomposite represents an efficient heterogeneous Fenton catalyst that can greatly promote the performance of advanced oxidation processes (AOPs) for solving practical environmental issues.
In this paper, type-I C3N4-based isotype heterojunction was prepared. In photocatalyisis-self-Fenton reaction, it displayed high H2O2 yield, outstanding utilization efficiency, and excellent ...degradation performance. The finding was beneficial to simultaneously solve two problems in traditional Fenton reaction: the source of H2O2 and low utilization efficiency.
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Herein, a type-I phosphorus-doped carbon nitride/oxygen-doped carbon nitride (P-C3N4/O-C3N4) heterojunction was designed for photocatalysis-self-Fenton reaction (photocatalytic H2O2 production and following Fenton reaction). In P-C3N4/O-C3N4, the photoinduced charge carriers were effectively separated with the help of internal-electric-field near the interface, ensuring the high catalytic performance. As a result, the production rate of H2O2 in an air-saturated solution was 179 μM·h−1, about 7.2, 2.5, 2.5 and 2.1 times quicker than that on C3N4, P-C3N4, O-C3N4, and phosphorus and oxygen co-doped C3N4, respectively. By taking advantage of the cascade mode in photocatalysis-self-Fenton reaction, H2O2 utilization efficiency was remarkably improved to 77.7%, about 9.0 times higher than that of traditional homogeneous Fenton reaction. Befitting from the superior yield and utilization efficiency, the degradation performance of P-C3N4/O-C3N4 was undoubtedly superior than other photocatalysts. This work well addressed two bottlenecks in traditional Fenton reaction: source of H2O2 and their low utilization efficiency, and the findings were beneficial to understand the mechanism and advantage of the photocatalysis-self-Fenton system in environmental remediation.
A direct Z-scheme BiOBr/Bi2Sn2O7 photocatalyst with abundant of surface OVs (Vo-BiOBr/Bi2Sn2O7) has been designed and synthesized which is applied for photocatalytic degradation under visible light ...irradiation. The as-prepared Vo-BiOBr/Bi2Sn2O7 heterojunctions with abundant surface OVs displays outstanding degradation performance and excellent stability.
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Promoting charge migration and enhancing redox ability of photogenerated carriers are important for the development of highly efficient semiconductor-based photocatalyst. Here, BiOBr/Bi2Sn2O7 heterojunction with oxygen vacancies (OVs) was constructed by homogeneously depositing Bi2Sn2O7 nanoparticles on the Vo-BiOBr surface. The experimental results manifested that Vo-BiOBr/Bi2Sn2O7 displayed better performance for rhodamine B, ciprofloxacin, and tetracycline degradation than counterparts without OVs. The characterization results proved OVs played the essential role for enhanced performance via improving the separation efficiency of charge carriers, increasing the visible light harvest, and lowering conduction band position. Moreover, mechanism study revealed that an inner electric field was built at the interface, leading to a Z-scheme path of photogenerated electron. This study provided an efficient strategy for designing highly efficient photocatalyst for solving environmental pollution.
Pine-needle-like CuCo2O4 nanocatalysts were prepared, and they displayed superior catalytic performance and reusability in a microwave-assisted Fenton reaction towards antibiotic metacycline.
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•Pine-needle-like CuCo2O4 were prepared by a hydrothermal method.•Reaction rate of CuCo2O4 nanoneedles was higher than reference samples.•Compared with heterogeneous Fenton reaction, Ea in MAFR was lowered 3.0 times.•86.4% of degradation efficiency was preserved after the 5th cycle.•Possible catalytic mechanism and degradation pathway were proposed.
The heterogeneous Fenton reaction was a powerful technique for degrading organics in wastewater. However, it usually took a long time to meet efficiency requirement. To solve this problem, herein, pine-needle-like CuCo2O4 was prepared and applied as a catalyst in a microwave-assisted Fenton reaction (MAFR) towards antibiotic metacycline (MTC). The optimized degradation condition was 500 μL of H2O2, 10.0 mg of catalyst, 50 mg/L of MTC, and 90 °C of temperature, under which MTC was degraded within 4.0 min. Dynamics data revealed that the activation energy of MAFR was 17.3 kJ/mol, which was much lower than that of the corresponding heterogeneous Fenton reaction (52.2 kJ/mol). Owing to the synergistic effect of combining Cu(II)/Cu(I) and Co(III)/Co(II) sites, the reaction rate constant of CuCo2O4 nanoneedles (7.2 × 10−1 min−1) was much higher than that of the CuO (1.3 × 10−1 min−1), Co3O4 (2.2 × 10−1 min−1), and mixed CuO + Co3O4 (1.5 × 10−1 min−1) references. CuCo2O4 nanoneedles could be easily separated from the reaction solution, and their degradation efficiency remained 86.4% after the 5th cycle. To study the catalytic mechanism, radical trapping experiments were performed, and the results revealed that OH played a dominating role in the degradation process. A possible degradation pathway of MTC was investigated, and it was determined that hydroxylation, de-alkylation, de-hydroxylation, and ring-opening reactions were involved for final inorganic molecules.
