Novel α-Fe2O3/polypyrrole nanocomposite with enhanced photocatalytic performance

Investigation of Doehlert matrix conception in novel intrinsically conducting polymers based on selenium nanoparticles for wastewater treatment: Synthesis, characterization, kinetic and chemometric study

The synthesis of robust intrinsically conducting polymers (ICPs) based on nanoparticles is becoming increasingly attractive to the research community due to the unique properties of these nanocomposites. Indeed, as organic semiconductors, ICPs combine both polymer and metal properties in a single structure. This study presents an innovative approach in which the Doehlert Matrix (DM) is applied to a novel ICP nanocomposite based on polyaniline (Pani) coupled with selenium (Se) loaded mesoporous titania (TiO2) for wastewater treatment by photocatalysis. It includes both the elaboration routes of ICP nanocomposites, characterization of materials by X-ray diffraction (XRD), BET analysis, thermogravimetric analysis (TGA), RAMAN spectroscopy and Fourier transform infrared spectroscopy (FTIR) and photodegradation of methylene blue (MB) as a representative of dye pollutant. In addition, the photocatalytic process has been optimized by a novel DM conception. The effect of the pH of the solution, the catalyst dosage and the initial pollutant concentration was investigated. The optimum conditions were found to be: initial MB concentration of 15 mg/L, the catalyst dosage of 69 mg and pH of 9.6 with an operating time of 75 min, with a coefficient of determination R2 equal to 0.9985. The removal efficiency of BM was close to 97 %. The study shows that the new ICP nanocomposites improve the photocatalytic efficiency compared to pure titania and/or pure Pani. In addition, as the ternary Pani-Se-TiO2 nanocomposite could be obtained from a low-cost synthesis, it is a very promising material for use in wastewater treatment.

Rational design of CdS-enwrapped polypyrrole nanoparticles for wastewater treatment: removal of hazardous pollutants in aqueous solutions

The modern world requires a chemical industry that can run at low production costs while producing high-quality products with minimal environmental impact. The development of environmentally friendly, cost-effective, and efficient wastewater treatment materials remains a major problem for the sustainable approach. We prepared nanoscale cadmium sulfide (CdS)-enwrapped polypyrrole (PPy) polymer composites for degradation of organic pollutants. The prepared CdS@PPy nanocomposites were characterized by powder X-ray diffraction, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible (UV) absorption spectroscopy, indicating proper intercalation between CdS and PPy. Consequently, the catalytic efficiency of the synthesized hybrid nanocomposites was analyzed through the degradation of methylene blue (MB) and rhodamine B (Rh B) under visible light irradiation. The measured degradation efficiency of the dye solutions under the photolysis process is about 18% and 23% for MB and Rh B dye, respectively. Furthermore, the recycle test result concludes that the CdS@PPy composite exhibits 91% and 89% of MB and Rh B dye degradation efficiency even at the 4th cycle, respectively. The positive synergistic impact of CdS and PPy may be the result of effective photocatalytic degradation of MB and RhB.

Conjugated Polymer Polypyrrole Nanostructures: Synthesis and Photocatalytic Applications

Conjugated polymers (CPs) have been recently widely investigated for their properties and their applications in different fields including photocatalysis. Among the family of CPs, polypyrrole (PPy) has been the most extensively studied owing to its good environmental stability, high electrical conductivity, superior redox properties and easy synthesis. Besides, nanostructured polypyrrole-based nanomaterials are a type of active organic materials for photocatalysis, which is one of their emerging applications. Nanostructuration of polypyrrole can reduce the electron-hole recombination because of short charge transfer distances and reactant adsorption, and product desorption can be enhanced owing to the high surface area offered by nanostructures. This review summarizes synthesis of different nanostructures based on π-conjugated polymer polypyrrole and the latest developments for photocatalytic applications, including degradation of organic pollutants and hydrogen generation.

Transforming type-II Fe2O3@polypyrrole to Z-scheme Fe2O3@polypyrrole/Prussian blue via Prussian blue as bridge: Enhanced activity in photo-Fenton reaction and mechanism insight

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.

Non-purified commercial multiwalled carbon nanotubes supported on electrospun polyacrylonitrile@polypyrrole nanofibers as photocatalysts for water decontamination

We present a photoactive composite material for water decontamination consisting of non-purified commercial multiwalled carbon nanotubes (CNT(NP)s) supported on an electrospun polymeric mat made of core-sheath polyacrylonitrile-polypyrrole nanofibers. This is the first system that specifically exploits the superior photocatalytic activity of CNT(NP)s compared with the purified carbon nanotubes usually employed. A CNT(NP) still contains the catalytic metal oxide nanoparticles (NPs) used for its synthesis, embedded in the nanotube structure. Under UV-visible irradiation, these NPs generate highly reactive ˙OH radicals capable of degrading the organic molecules adsorbed on the nanotube. Photocatalytic tests on the composite material show that CNT(NP)s act mostly as a source of photogenerated charge carriers. The adsorption of target substrates occurs preferentially onto the polypyrrole sheath, which shuttles the reactive carriers from CNT(NP)s to the substrates. In addition, UV-visible irradiation of semiconducting polypyrrole generates radical species that directly react with the adsorbed substrates. All synthetic procedures reported are scalable and sustainable. This mechanically resistant and flexible composite overcomes one of the weakest aspects of water treatments that employ suspended nanocatalysts, namely the expensive and poorly scalable recovery of the catalyst through nanofiltration. All these features are required for large-scale photocatalytic treatments of polluted water.

Highly Sensitive Ethanol Chemical Sensor Based on Novel Ag-Doped Mesoporous α-Fe2O3 Prepared by Modified Sol-Gel Process

Mesoporous α-Fe₂O₃ has been synthesized via a simple sol-gel procedure in the presence of Pluronic (F-127) triblock copolymer as structure directing agent. Silver (Ag) nanoparticles were deposited onto α-Fe₂O₃ matrix by the photochemical reduction approach. Morphological analysis revealed the formation of Ag nanoparticles with small sizes < 20 nm onto the mesoporous structure of α-Fe₂O₃ possessing < 50 nm semi-spherical shape. The XRD, FTIR, Raman, UV-vis, PL, and N₂ sorption isotherm studies confirmed the high crystallinity, mesoporosity, and optical characteristics of the synthesized product. The electrochemical sensing toward liquid ethanol has been performed using the current devolved Ag/α-Fe₂O₃-modified glassy carbon electrode (GCE) by cyclic voltammetry (CV) and current potential (I-V) techniques, and the obtained results were compared with bare GCE or pure α-Fe₂O₃. Mesoporous Ag/α-Fe₂O₃ was found to largely enhance the sensor sensitivity and it exhibited excellent sensing characteristics during the precision detection of low concentrations of ethanol. High and reproducible sensitivity of 41.27 μAmM^- 1 cm^- 2 at lower ethanol concentration region (0.05 to 0.8 mM) and 2.93 μAmM^- 1 cm^- 2 at higher concentration zone (0.8 to 15 mM), with a limit of detection (LOD) of 15.4 μM have been achieved. Investigation on reaction kinetics revealed a characteristic behavior of mixed surface and diffusion-controlled processes. Detailed sensing studies revealed also that the sensitivity toward ethanol was higher than that of methanol or isopropanol. With further effort in developing the synthesis and fabrication approaches, a proper utility for the current proposed protocol for fabricating a better sensor device performance is possible.

Novel Bi2O2CO3/polypyrrole/g-C3N4 nanocomposites with efficient photocatalytic and nonlinear optical properties

A series of novel Bi₂O₂CO₃/polypyrrole/g-C₃N₄ nanocomposites loaded with different contents of g-C₃N₄ was demonstrated for recyclable photocatalysis and nonlinear optical applications.

Solvent-less method for efficient photocatalytic α-Fe2O3 nanoparticles using macromolecular polymeric precursors

Efficient photocatalytic degradation of persistent cationic dye pollutants under visible light is possible with Fe₂O₃ nanoparticles formed by solvent-less synthesis using macromolecular precursor design.