Synthesis of α-Fe2O3 decorated g-C3N4/ZnO ternary Z-scheme photocatalyst for degradation of tartrazine dye in aqueous media

High photocatalytic efficiency of a ZnO nanoplate/Fe2O3 nanospindle hybrid using visible light for methylene blue degradation

In this work, ZnO nanoplates and Fe2O3 nanospindles were successfully fabricated via a simple hydrothermal method using inorganic salts as precursors. The ZnO/Fe2O3 hybrid was fabricated using a mechanical mixture of two different ZnO : Fe2O3 weight ratios to investigate the effect of weight ratio on catalytic properties. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that ZnO nanoplates (NPls) are about 20 nm thick with lateral dimensions of 100 × 200 nm, and Fe2O3 nanospindles (NSs) are about 500 nm long and 50 nm wide. X-ray diffraction (XRD) patterns revealed the successful formation of the ZnO, Fe2O3, and ZnO/Fe2O3 samples and indicated that their crystallite sizes varied from 20 to 29 nm depending on the ZnO : Fe2O3 weight ratio. Ultraviolet-visible (UV-vis) spectra showed that the bandgap energies of ZnO and Fe2O3 were 3.15 eV and 2.1 eV, respectively. Energy dispersive X-ray spectroscopy (EDS) results revealed the successful combination of ZnO and Fe2O3. Photocatalytic activity of the materials was evaluated through the degradation of methylene blue (MB) in aqueous solution under green light-emitting diode (GLED) irradiation. The results indicated that the ZnO/Fe2O3 composite showed a remarkable enhanced degradation capacity compared to bare ZnO NPls and Fe2O3 NSs. The ZnO : Fe2O3 = 3 : 2 sample demonstrated the best performance among all samples under identical conditions with a degradation efficiency of 99.3% for MB after 85 min. The optimum photocatalytic activity of the sample with ZnO : Fe2O3 = 3 : 2 was nearly 3.6% higher than that of the pure ZnO sample and 1.12 times more than that of the pristine Fe2O3 sample. Moreover, the highest photo-degradation was obtained at a photocatalyst dosage of 0.25 g l-1 in dye solution.

Synergistic effect of ZnO/Ag2O@g-C3N4 based nanocomposites embedded in carrageenan matrix for dye degradation in water

This research achieved success by synthesizing innovative nanocomposite composed of zinc oxide (ZnO), graphitic carbon nitride (g-C3N4) and silver oxide (Ag2O) nanomaterials incorporated into a carrageenan matrix, thus creating an environmentally friendly and stable support structure. The synthesis process involved hydrothermal and chemical precipitation methods to create photocatalytic g-C3N4, ZnO, and Ag2O nanocomposites. The success is evident through the characterization results, which unveiled distinctive peaks corresponding to Zn-O (590-404 cm-1) and Ag-O (2072 cm-1) stretching in the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, conclusively confirming the successful synthesis of g-C3N4, ZnO, Ag2O, and their respective nanocomposites. Further validation through a scanning electron microscope coupled with an energy dispersive spectrometer (SEM-EDX) and elemental mapping affirmed the presence of Zn, O, Ag, C, and N. Additionally, transmission electron microscope (TEM) imaging unveiled the nanosheet morphology of g-C3N4, the nanorod structure of ZnO, and the spherical form of Ag2O nanomaterials. ZnO and Ag2O nanomaterials demonstrated a consistent 10-20 nm size range. To underscore their ability to harness visible light, the nanomaterials were excited at 380 nm, emitting visible light emission within the 400-450 nm range. The synthesized nanocomposites showcased outstanding adsorption and photocatalytic properties, achieving efficiency ranging from 80 % to 98 %, attributed to the synergistic interactions between the various components. These findings culminate in a confirmation of the research's success, validating the exceptional potential of these nanocomposites for various applications.

Silver-decorated SrTiO3 nanoparticles for high-performance supercapacitors and effective remediation of hazardous pollutants

SrTiO3/Ag nanocomposites were synthesized using a facile wet impregnation method, employing rigorous experimental techniques for comprehensive characterization. XRD, FTIR, UV, PL, FESEM, and HRTEM were meticulously utilized to elucidate their structural, functional, morphological, and optical properties. The electrochemical performance of the SrTiO3/Ag nanocomposite was rigorously assessed, revealing an impressive specific capacitance of 850 F/g at a current density of 1 A. Furthermore, the photocatalytic activity of the SrTiO3/Ag nanocomposite was rigorously examined using methylene blue (MB) dye, and the results were outstanding. After 120 min of UV irradiation, the nanocomposite exhibited an exceptional MB dye degradation efficiency exceeding 88%. The SrTiO3/Ag nanocomposite represents an exemplary catalyst in terms of efficiency, cost-effectiveness, environmental compatibility, and reusability. The electron and superoxide radicals play a chief role in the MB dye degradation process. The inclusion of Ag within the SrTiO3 matrix facilitated the formation of a conductive nano-network, ultimately resulting in superior capacitive and photocatalytic performance.

Flower shaped Bi2O2.33/Bi2WO6 composite: An efficient photocatalyst for degradation of methylene blue from aqueous solution in direct solar light

Herein, we synthesized a Bi2O2.33/Bi2WO6 heterostructure as a platform for the degradation of methylene blue (MB) dye in an aqueous phase. The heterostructure was synthesized by facile ultrasonicated assisted solvothermal method. Various structural, morphological and other techniques such as XRD, FTIR, PL, EIS, UV-DRS, FESEM, HRTEM, XPS, EPR, TGA, BET surface area were used to analyze the characteristics of as-synthesized Bi2O2.33/Bi2WO6. The morphological studies revealed the deposition of Bi2O2.33 flowers in high density on Bi2WO6. Under solar irradiation, 98.6% degradation of MB was achieved in 190 min at optimal conditions (pH = 5, catalyst dose = 0.35 gL-1 and MB concentration = 10 mgL-1). The improved photocatalytic ability of composite in contrast to Bi2O2.33 and Bi2WO6 could be usually ascribed to the interface created between them, assisting the charge transfer. Based on the findings of radical trapping experiments, the charge transfer process over the photocatalyst was completely studied. Additionally, the present heterostructure demonstrated good recyclability over five runs. In nutshell, this study provided a facile approach for synthesizing solar light driven photocatalyst for degradation of methylene blue in aqueous phase and can further explored to be utilized for varied environmental remediation.

Graphitic Carbon Nitride/Zinc Oxide-Based Z-Scheme and S-Scheme Heterojunction Photocatalysts for the Photodegradation of Organic Pollutants

Graphitic carbon nitride (g-C3N4), a metal-free polymer semiconductor, has been recognized as an attractive photocatalytic material for environmental remediation because of its low band gap, high thermal and photostability, chemical inertness, non-toxicity, low cost, biocompatibility, and optical and electrical efficiency. However, g-C3N4 has been reported to suffer from many difficulties in photocatalytic applications, such as a low specific surface area, inadequate visible-light utilization, and a high charge recombination rate. To overcome these difficulties, the formation of g-C3N4 heterojunctions by coupling with metal oxides has triggered tremendous interest in recent years. In this regard, zinc oxide (ZnO) is being largely explored as a self-driven semiconductor photocatalyst to form heterojunctions with g-C3N4, as ZnO possesses unique and fascinating properties, including high quantum efficiency, high electron mobility, cost-effectiveness, environmental friendliness, and a simple synthetic procedure. The synergistic effect of its properties, such as adsorption and photogenerated charge separation, was found to enhance the photocatalytic activity of heterojunctions. Hence, this review aims to compile the strategies for fabricating g-C3N4/ZnO-based Z-scheme and S-scheme heterojunction photocatalytic systems with enhanced performance and overall stability for the photodegradation of organic pollutants. Furthermore, with reference to the reported system, the photocatalytic mechanism of g-C3N4/ZnO-based heterojunction photocatalysts and their charge-transfer pathways on the interface surface are highlighted.

Effects of iron oxide contents on photocatalytic performance of nanocomposites based on g-C3N4

α-Fe₂O₃/Fe₃O₄/g-C₃N₄ nanocomposites were prepared in-situ by solution combustion as magnetically separable photocatalysts using ferric nitrate as oxidant, glycine as organic fuel, and g-C₃N₄. The effects of various amounts of iron oxides, on the magnetic, optical, and photocatalytic properties were explored by different characterization methods. The magnetite (Fe₃O₄) phase as ferrimagnetic material disappeared with the increase in ferric nitrate contents, leading to the decrease of magnetic properties. The bandgap energy decreased from 2.8 to 1.6 eV with the increase of the hematite (α-Fe₂O₃) phase.The photocatalytic results showed that the type and amount of iron oxides had a significant effect on the decolorization of methylene blue, rhodamine B and methyl orange dyes under visible-light irradiation. The activity of the nanocomposite sample containing 37 wt. % iron oxides was more effective than that of the pristine g-C₃N₄ sample to photodegrade the methylene blue, rhodamine B and methyl orange, respectively. Moreover, the nanocomposites exhibited a higher photocurrent density than that of the pristine g-C₃N₄, mainly due to their lower charge recombination rate.

Photo-Oxidation of Organic Dye by Fe2O3 Nanoparticles: Catalyst, Electron Acceptor, and Polyurethane Membrane (PU-Fe2O3) Effects

The textile industry’s discharges have long been regarded as severe water pollution. The photocatalytic degradation of dyes using semiconductors is one of the crucial methods. The present study efficiently used the mechanical method to synthesize Iron oxide Nanoparticles. XRD, FT-IR, UV-Vis DRS, and Raman analyses were performed to analyze the structural and optical. From the data provided by XRD and Raman data, we believed that the as-synthesized Iron oxide was pure hematite (α-Fe2O3) with a hexagonal structure. Additionally, the EDS results show that the synthesized material is pure. By adjusting specific parameters, including the dye concentration, the catalyst dosage, the pH, and the oxidizing agent such as H2O2 and K2S2O8, the degradation of eosin yellowish using Fe2O3 as a photocatalyst has been discussed. Additionally, the kinetics of eosin yellowish degradation has been studied. A study was also conducted using Fe2O3 nanoparticles attached to polyurethane polymer (PU) to investigate its photocatalytic activity on methylene blue, methyl orange, and indigo carmine. In 30 minutes, nearly 90% of the dyes had degraded. The total organic carbon (TOC) analysis confirmed this result.

Hydrothermal Synthesis of Bimetallic (Zn, Co) Co-Doped Tungstate Nanocomposite with Direct Z-Scheme for Enhanced Photodegradation of Xylenol Orange

In the present study, pristine ZnWO4, CoWO4, and mixed metal Zn0.5Co0.5WO4 were synthesized through the hydrothermal process using a Teflon-lined autoclave at 180 ℃. The synthesized nanomaterials were characterized by various spectroscopic techniques, such as TEM, FTIR, UV–vis, XRD, and SEM-EDX-mapping to confirm the formation of nanocomposite material. The synthesized materials were explored as photocatalysts for the degradation of xylenol orange (XO) under a visible light source and a comparative study was explored to check the efficiency of the bimetallic co-doped nanocomposite to the pristine metal tungstate NPs. XRD analysis proved that reinforcement of Co2+ in ZnWO4 lattice results in a reduction in interplanar distance from 0.203 nm to 0.185 nm, which is reflected in its crystallite size, which reduced from 32 nm to 24 nm. Contraction in crystallite size reflects on the optical properties as the energy bandgap of ZnWO4 reduced from 3.49 eV to 3.33 eV in Zn0.5Co0.5WO4, which is due to the formation of a Z-scheme for charge transfer and enhancement in photocatalytic efficiency. The experimental results suggested that ZnWO4, CoWO4, and Zn0.5Co0.5WO4 NPs achieved a photocatalytic efficiency of 97.89%, 98.10%, and 98.77% towards XO in 120 min of visible solar light irradiation. The kinetics of photodegradation was best explained by pseudo-first-order kinetics and the values of apparent rate const (kapp) also supported the enhanced photocatalytic efficiency of mixed metal Zn0.5Co0.5WO4 NPs towards XO degradation.

Highly effectual photocatalytic degradation of tartrazine by using Ag nanoparticles decorated on Zn-Cu-Cr layered double hydroxide@ 2D graphitic carbon nitride (C3N5)

Pollution of water resources is one of the main concerns of many countries. This issue originates from the entry of diverse pollutants, including dye compounds, into water sources. In this work, ternary Zn-Cu-Cr layered double hydroxides (LDH) supported on graphitic carbon nitride (g-C₃N₅) decorated by silver nanoparticles (C₃N₅-LDH-Ag) was first prepared. Application of various characterization techniques such as SEM, XRD, and FT-IR revealed that the synthesized nanocomposite was composed of Zn-Cu-Cr LDH nanoparticles, g-C₃N₅ nanosheets, and Ag nanoparticles. The prepared nanomaterials were employed for the photodegradation of tartrazine in aqueous solutions. It was found that the C₃N₅-LDH-Ag catalyst outperformed their pure g-C₃N₅, Zn-Cu-Cr LDH, and C₃N₅-LDH composite in photocatalytic degradation of tartrazine under visible light irradiation. Tartrazine (20 mg/L) can be entirely removed by 0.25 g/L C₃N₅-LDH-Ag photocatalyst under 1 h visible light irradiation (200 W) at pH 6 with a rapid degradation rate constant (k) that is 4.4, 3.9, and 2.6 times higher than that of pure C₃N₅, Zn-Cu-Cr LDH, and C₃N₅-LDH component, respectively. The formation of hydroxyl radicals on the surface of C₃N₅-LDH-Ag as the main active species was approved by the capturing experiment. The finding results approved the stability and reusability of C₃N₅-LDH-Ag in four photocatalytic degradation cycles. In general, our findings revealed that the synthesized nanocomposite could be employed as an efficient photocatalyst in environmental remediation.

Metal ferrites-based nanocomposites and nanohybrids for photocatalytic water treatment and electrocatalytic water splitting

Photocatalytic degradation is one of the most promising technologies available for removing a variety of synthetic and organic pollutants from the environmental matrices because of its high catalytic activity, reduced energy consumption, and low total cost. Due to its acceptable bandgap, broad light-harvesting efficiency, significant renewability, and stability, Fe₂O₃ has emerged as a fascinating material for the degradation of organic contaminants as well as numerous dyes. This study thoroughly reviewed the efficiency of Fe₂O₃-based nanocomposite and nanomaterials for water remediation. Iron oxide structure and various synthetic methods are briefly discussed. Additionally, the electrocatalytic application of Fe₂O₃-based nanocomposites, including oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, and overall water splitting efficiency, was also highlighted to illustrate the great promise of these composites. Finally, the ongoing issues and future prospects are directed to fully reveal the standards of Fe₂O₃-based catalysts. This review is intended to disseminate knowledge for further research on the possible applications of Fe₂O₃ as a photocatalyst and electrocatalyst.

Synthesis of Highly Efficient (0D/1D) Z-Scheme CdS-NPs@ZnO-NRs Visible-Light-Driven Photo(electro)catalyst for PEC Oxygen Evolution Reaction and Removal of Tetracycline

Herein, we synthesized the cadmium sulfide nanoparticles (CdS-NPs) coated zinc oxide nanorods (ZnO-NRs) core-shell like CdS-NPs@ZnO-NRs heterojunction for photo(electro)chemical applications. The CdS-NPs and ZnO-NRs were synthesized through a simple hydrothermal path. The physicochemical and optoelectronic properties of the as-prepared catalysts are characterized by various spectroscopy techniques, such as FTIR, XRD, SEM, TEM, EDX, VB-XPS, DRS, and PL. The photocatalytic performances of the CdS-NPs@ZnO-NRs catalyst were evaluated by photodegradation of tetracycline (TC) in aqueous media under visible-light irradiation, which demonstrated 94.07 % of removal (k’ = 0.0307 min−1) within 90 min. On the other hand, the photoelectrochemical (PEC) water-oxidation/oxygen-evolution reaction (OER) was performed, which resulted in the photocurrent density of 3.002 mA/cm2 and overpotential (at 2 mA/cm2) of 171 mV (vs RHE) in 1.0 M KOH under AM 1.5G illumination. The reactive species scavenging experiment demonstrates the significant contributions of photogenerated holes towards TC removal. Furthermore, the Z-scheme CdS-NPs@ZnO-NRs core-shell heterojunction exhibits high efficiency, recyclability, and photostability, demonstrating that the CdS-NPs@ZnO-NRs is a robust photo(electro)catalyst for visible-light PEC applications.

Enhanced Room-Temperature Ethanol Detection by Quasi 2D Nanosheets of an Exfoliated Polymeric Graphitized Carbon Nitride Composite-Based Patterned Sensor

A novel room-temperature gas sensor composed of polymeric graphitic carbon nitride composite was fabricated and used for the detection of ethanol vapor under ambient conditions. Polymeric carbon nitride (PCN) microstructures composed of fluffy nanosheets were synthesized via a thermal polycondensation mechanism using melamine as the precursor, followed by vigorous chemical exfoliation. These sheet-like microstructures were employed as active materials in the form of composites, along with carbon paste consisting of graphite nanoplatelets and carbon black. The active sensing layer was fabricated on a PET sheet and assembled on an interdigitated gold electrode. The as-fabricated sensor exhibited excellent sensing efficiency (>100% response at 10 ppm) along with high selectivity and stability. In particular, for ultralow concentrations such as 1 ppm (>10% response), this resistive-based sensor exhibited a swift response time provided under ambient conditions. The exfoliated PCN composite sensor was found to be working with appreciable efficiency at moderate relative humidity (%) with the least fluctuation in response signals also demonstrating long-term stability for 30 days with consistent response signals.

Research Progress on Graphitic Carbon Nitride/Metal Oxide Composites: Synthesis and Photocatalytic Applications

Although graphitic carbon nitride (g-C3N4) has been reported for several decades, it is still an active material at the present time owing to its amazing properties exhibited in many applications, including photocatalysis. With the rapid development of characterization techniques, in-depth exploration has been conducted to reveal and utilize the natural properties of g-C3N4 through modifications. Among these, the assembly of g-C3N4 with metal oxides is an effective strategy which can not only improve electron-hole separation efficiency by forming a polymer-inorganic heterojunction, but also compensate for the redox capabilities of g-C3N4 owing to the varied oxidation states of metal ions, enhancing its photocatalytic performance. Herein, we summarized the research progress on the synthesis of g-C3N4 and its coupling with single- or multiple-metal oxides, and its photocatalytic applications in energy production and environmental protection, including the splitting of water to hydrogen, the reduction of CO2 to valuable fuels, the degradation of organic pollutants and the disinfection of bacteria. At the end, challenges and prospects in the synthesis and photocatalytic application of g-C3N4-based composites are proposed and an outlook is given.

Use of the CuFe2O4/biochar composite to remove methylene blue, methyl orange and tartrazine dyes from wastewater using photo-Fenton process

In this study, CuFe₂O₄ ferrite was supported on biochar produced from malt biomass residues as a photocatalyst for degradation of methylene blue (MB), methyl orange (MO), and tartrazine (TZ) dyes. XRD, FT-IR, and FE-SEM were used to characterize the crystallinity and morphology of the samples. The characterization showed that the ferrite was uniformly supported on the surface of the biochar, confirming the formation of the composite. Degradation tests showed that CuFe₂O₄ degraded approximately 50, 47, and 62% of MB, MO, and TZ dyes, respectively, after 60 min of reaction. On the other hand, the CuFe₂O₄/biochar composite showed a significant increase in dye degradation, ~ 100%, for all three dyes. This increase in degradation efficiency may be due to less agglomeration of supported particles and due to decreased recombination of electron/hole pairs. Thus, results showed that the photocatalyst composite produced in this study is an effective alternative for removing dyes from wastewater.

Enhanced artificial intelligence for electrochemical sensors in monitoring and removing of azo dyes and food colorant substances

It is necessary to determine whether synthetic dyes are present in food since their excessive use has detrimental effects on human health. For the simultaneous assessment of tartrazine and Patent Blue V, a novel electrochemical sensing platform was developed. As a result, two artificial azo colorants (Tartrazine and Patent Blue V) with toxic azo groups (-NN-) and other carcinogenic aromatic ring structures were examined. With a low limit of detection of 0.06 μM, a broad linear concentration range 0.09μM to 950μM, and a respectable recovery, scanning electron microscopy (SEM) was able to reveal the excellent sensing performance of the suggested electrode for patent blue V. The electrochemical performance of an electrode can be characterized using cyclic and differential pulse voltammetry, and electrochemical impedance spectroscopy. Moreover, the classification model was created by applying binary classification assessment using enhanced artificial intelligence comprises of support vector machine (SVM) and Genetic Algorithm (GA), respectively, a support vector machine and a genetic algorithm, which was then validated using the 50 dyes test set. The best binary logistic regression model has an accuracy of 83.2% and 81.1%, respectively, while the best SVM model has an accuracy of 90.3% for the training group of samples and 81.1% for the test group (RMSE = 0.644, R2 = 0.873, C = 205.41, and = 5.992). According to the findings, Cu-BTC MOF (copper (II)-benzene-1,3,5-tricarboxylate) has a crystal structure and is tightly packed with hierarchically porous nanomaterials, with each particle's edge measuring between 20 and 37 nm. The suggested electrochemical sensor's analytical performance is suitable for foods like jellies, condiments, soft drinks and candies.

Recent advances and perspectives of g-C3N4-based materials for photocatalytic dyes degradation

Photocatalytic degradation technology is regarded as a promising technology for dye-contained wastewater treatment due to its superior efficiency and recycling. The key to the implementation of photocatalytic degradation technology is the selection of sunlight-active photocatalyst. Graphitic carbon nitride (g-C₃N₄) photocatalyst has been put into a lot of research in the field of organic pollutant degradation because of its low cost, suitable electronic structure and high chemical stability. In this perspective review, we comprehensively discuss the recent advance of photocatalytic dyes degradation over g-C₃N₄-based materials. The properties, structure and preparation methods of g-C₃N₄ are briefly introduced. Furthermore, the progress in improving the degradation efficiency of g-C₃N₄-based photocatalyst is highlighted in the article. The possible pathways and different active species for dyes decomposition are also summarized. We expect this review can provide instructive application of g-C₃N₄-based catalysts for environmental remediation.

Recent advancements of g-C3N4-based magnetic photocatalysts towards the degradation of organic pollutants: a review

Heterogeneous photocatalysis premised on advanced oxidation processes has witnessed a broad application perspective, including water purification and environmental remediation. In particular, the graphitic carbon nitride (g-C₃N₄), an earth-abundant metal-free conjugated polymer, has acquired extensive application scope and interdisciplinary consideration owing to its outstanding structural and physicochemical properties. However, several issues such as the high recombination rate of the photo-generated electron-hole pairs, smaller specific surface area, and lower electrical conductivity curtail the catalytic efficacy of bulk g-C₃N₄. Another challenging task is separating the catalyst from the reaction medium, limiting their reusability and practical applications. Therefore, several methodologies are adopted strategically to tackle these issues. Attention is being paid, especially to the magnetic nanocomposites (NCs) based catalysts to enhance efficiency and proficient reusability property. This review summarizes the latest progress related to the design and development of magnetic g-C₃N₄-based NCs and their utilization in photocatalytic systems. The usefulness of the semiconductor heterojunctions on the catalytic activity, working mechanism, and degradation of pollutants are discussed in detail. The major challenges and prospects of using magnetic g-C₃N₄-based NCs for photocatalytic applications are highlighted in this report.

Advances in the Application of Nanocatalysts in Photocatalytic Processes for the Treatment of Food Dyes: A Review

The use of food additives (such as dyes, which improve the appearance of the products) has become more prominent, due to the rapid population growth and the increase in demand for beverages and processed foods. The dyes are usually found in effluents that are discharged into the environment without previous treatment; this promotes mass contamination and alters the aquatic environment. In recent years, advanced oxidation processes (AOPs) have proven to be effective technologies used for wastewater treatment through the destruction of the total organic content of toxic contaminants, including food dyes. Studies have shown that the introduction of catalysts in AOPs improve treatment efficiency (i.e., complete decomposition without secondary contamination). The present review offers a quick reference for researchers, regarding the treatment of wastewater containing food dyes and the different types of AOPs, with different catalyst and nanocatalyst materials obtained from traditional and green chemical syntheses.

Morphology-Controlled Synthesis of α-Fe2O3 Nanocrystals Impregnated on g-C3N4-SO3H with Ultrafast Charge Separation for Photoreduction of Cr (VI) Under Visible Light

Surface functionalization and shape modifications are the key strategies being utilized to overcome the limitations of semiconductors in advanced oxidation processes (AOP). Herein, the uniform α-Fe₂O₃ nanocrystals (α-Fe₂O₃-NCs) were effectively synthesized via a simple solvothermal route. Meanwhile, the sulfonic acid functionalization (SAF) and the impregnation of α-Fe₂O₃-NCs on g-C₃N₄ (α-Fe₂O₃-NCs@CN-SAF) were achieved through complete solvent evaporation technique. The surface functionalization of the sulfonic acid group on g-C₃N₄ accelerates the faster migration of electrons to the surface owing to robust electronegativity. The incorporation of α-Fe₂O₃-NCs with CN-SAF significantly enhances the optoelectronic properties, ultrafast spatial charge separation, and rapid charge transportation. The α-Fe₂O₃-HPs@CN-SAF and α-Fe₂O₃-NPs@CN-SAF nanocomposites attained 97.41% and 93.64% of Cr (VI) photoreduction in 10 min, respectively. The photocatalytic efficiency of α-Fe₂O₃-NCs@CN-SAF nanocomposite is 2.4 and 2.1 times higher than that of pure g-C₃N₄ and α-Fe₂O₃, respectively. Besides, the XPS, PEC and recycling experiments confirm the excellent photo-induced charge separation via Z-scheme heterostructure and cyclic stability of α-Fe₂O₃-NCs@CN-SAF nanocomposites.

Comparison of Enhanced Photocatalytic Degradation Efficiency and Toxicity Evaluations of CeO2 Nanoparticles Synthesized Through Double-Modulation

We demonstrated that Fe/Cr doped and pH-modified CeO₂ nanoparticles (NPs) exhibit enhanced photocatalytic performance as compared to bare CeO₂ NPs, using photocatalytic degradation. To assess the toxicity level of these double-modified CeO₂ NPs on the human skin, they were introduced into HaCaT cells. The results of our conventional cellular toxicity assays (neutral red uptake and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide for assays) indicated that Cr@CeO_x NPs prompt severe negative effects on the viability of human cells. Moreover, the results obtained by scanning transmission X-ray microscopy and bio-transmission electron microscope analysis showed that most of the NPs were localized outside the nucleus of the cells. Thus, serious genetic toxicity was unlikely. Overall, this study highlights the need to prevent the development of Cr@CeO_x NP toxicity. Moreover, further research should aim to improve the photocatalytic properties and activity of these NPs while accounting for their stability issues.

Fabrication of CuWO4/Bi2S3/ZIF67 MOF: A novel double Z-scheme ternary heterostructure for boosting visible-light photodegradation of antibiotics

A novel double Z-scheme CuWO₄/Bi₂S₃/ZIF67 ternary heterostructure was synthesized through hydrothermal method. The catalysts were characterized by XRD, FTIR, SEM, EDX, BET, TEM, PL, and UV-vis DRS analyses. The degradations of Metronidazole (MTZ) and Cephalexin (CFX) antibiotics by ternary catalyst were investigated in the batch and continuous slurry photoreactor under LED illumination. The ternary heterostructure exhibited a remarkable improvement in photoactivity compared with CuWO₄/Bi₂S₃, and pristine ZIF67. Indeed, higher surface area, photo-stability, bandgap suppressing as well as better charge separation based on the dual Z-scheme structure caused the enhancement. The optimum values of operating parameters were obtained by the central composite design as: catalyst dose = 0.3 g/L, pH = 7, illumination time = 80 min, and 20 ppm initial concentration of antibiotic. The maximum degradation efficiencies by the new ternary heterostructure were 95.6% and 90.1%, respectively for MTZ and CFX at optimum conditions in the continuous flow mode. Maximum total organic carbon (TOC) removal rates were 83.2% and 74% for MTZ and CFX, respectively. The degradations by ternary composite followed the first-order kinetic, by reaction rate of 9 times, 5.5 times, and 4 times higher than that obtained by Bi₂S_3, ZIF67, and the binary CuWO₄/Bi₂S₃, respectively_. The influences of temperature and light intensity were explored, revealing 25 °C and 400 W/m² as the optimum values. The new ternary heterostructure demonstrated excellent reusability and chemical stability after six cycles. The dominant active species were explored by trapping tests, indicating OH^. free radicals as the most primary oxidant.

Preparation of solar-enhanced AlZnO@carbon nano-substrates for remediation of textile wastewaters

Photoactive aluminum doped ZnO (AlZnO) was synthesized by sol-gel method. After that, AlZnO photocatalyst was deposited on five carbon-based materials (CBMs) using ultrasonic route followed by solid-state mixing using ball mill. The CBMs used were polyaniline (PANI), carbon nitride (CN), carbon nanotubes (CNT), graphene (G), and carbon nanofibers (CNF). The crystal phases, elemental compositions, morphological, and optical properties of the AlZnO@CBMs composites were investigated. Experimental results revealed that two of AlZnO@CBMs composites exhibited superior bleaching efficiency (100% removal) and photocatalytic stability (three cycles) for 50 μmol/L Methylene Blue (MB) contaminated water after 60 min irradiation in visible light at pH 6.5, 0.7% H₂O₂, and 5 g/L inorganic salts. Under optimum conditions, AlZnO@CBMs nanocomposites were employed for the treatment of mixed dyestuffs composed of MB, Methyl Orange (MO), Astrazone Blue FRR (BB 69), and Rhodamine B (RhB) dyes under dark, ultraviolet, visible, and direct sunlight. For mixed dyestuffs, the AlZnO@G achieved the highest dye sorption capacity (60.91 μmol dye stuffs/g) with kinetic rate 8.22 × 10^-3 min^-1 in 90 min via multi-layer physisorption (Freundlich isotherm) on graphene sheet. In additions, AlZnO@CN offered the highest photo-kinetic rate (K_photo) of ~54.1 × 10^-3 min^-1 (93.8% after 60 min) under direct sunlight. Furthermore, the selective radical trapping experiment confirmed that the holes and oxidative superoxide radicals are crucial on dyes photodegradation pathway. Owing to their superior performance, AlZnO@G and AlZnO@CN nanocomposites can offer an effective in-situ solar-assisted adsorption/photocatalytic remediation of textile wastewater effluents.

A review on exploration of Fe2O3 photocatalyst towards degradation of dyes and organic contaminants

Photocatalytic degradation is among the promising technology for removal of various dyes and organic contaminants from environment owing to its excellent catalytic activity, low energy utilization, and low cost. As one of potential photocatalysts, Fe₂O₃ has emerged as an important material for degradation of numerous dyes and organic contaminants caused by its tolerable band gap, wide harvesting of visible light, good stability and recyclability. The present review thoroughly summarized the classification, synthesis route of Fe₂O₃ with different morphologies, and several modifications of Fe₂O₃ for improved photocatalytic performance. These include the incorporation with supporting materials, formation of heterojunction with other semiconductor photocatalysts, as well as the fabrication of Z-scheme. Explicitly, the other photocatalytic applications of Fe₂O₃, including for removal of heavy metals, reduction of CO₂, evolution of H₂, and N₂ fixation are also deliberately discussed to further highlight the huge potential of this catalyst. Moreover, the prospects and future challenges are also comprised to expose the unscrutinized criteria of Fe₂O₃ photocatalyst. This review aims to contribute a knowledge transfer for providing more information on the potential of Fe₂O₃ photocatalyst. In the meantime, it might give an idea for utilization of this photocatalyst in other environmental remediation application.

Facile synthesis of a novel nitrogen-doped carbon dot adorned zinc oxide composite for photodegradation of methylene blue

Nitrogen-doped carbon dot decorated zinc oxide nanoparticles were successfully fabricated by an economical wet-impregnation method and used as a photocatalyst for the degradation of aqueous methylene blue dye under UV-light at room temperature.