Application In Photocatalytic Degradation Research Articles

Construction of Spinel/Perovskite Heterojunction for Boosting Photocatalytic Performance for Polyacrylamide

The use of photocatalytic technology to degrade polyacrylamide in crude oil extraction wastewater is a promising approach, but there have been few reports so far. In this study, ZnFe2O4/Ba0.7Sr0.3TiO3 heterogeneous composite materials of a spinel/perovskite type with different proportions were synthesized. The composite materials with 31% ZnFe2O4 content exhibited a maximum polyacrylamide degradation efficiency of 46.54%, which demonstrated the unique role of the spinel/perovskite heterogeneous structure. When Ag nanoparticles were grown in situ on the surface of ZnFe2O4/Ba0.7Sr0.3TiO3, the photocatalytic degradation efficiency reached 81.28%. The main reason was that the introduction of Ag nanoparticles not only increased the active sites and enhanced light absorption capacity but also accelerated the separation of photo-generated charges. This work provides new ideas for the construction of spinel/perovskite heterogeneous composite materials and has reference significance for the application of photocatalytic degradation in the treatment of wastewater-containing polymers.

Green synthesis of silver nanoparticles using Adhatoda vasica leaf extract and its application in photocatalytic degradation of dyes

The paper describes biogenic synthesis of silver nanoparticles (AgNPs) using Adhatoda vasica leaf extracts at room temperature. The prepared AgNPs were characterized by UV–visible spectroscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, Energy dispersive X-ray (EDX), High Resolution Transmission Electron Microscope, Scanning Electron Microscopy and Thermogravimetric analyser. The bio reduction method is devoid of any toxic chemicals, organic solvents, and external reducing, capping and stabilizing agent. The synthesized AgNPs had spherical shape with particle size ranging between 3.88 and 23.97 nm and had face centered cubic structure. UV–visible spectral analysis confirmed the formation of AgNPs with a characteristic surface plasmon resonance band at 419 nm. The EDX pattern revealed the presence of elemental Ag in AgNPs. The prepared AgNPs were used for degradation of Amaranth, Allura red and Fast green in aqueous medium, with ≥ 92.6% efficiency within 15 min using 5 mg of AgNPs. The optical bandgap, Eg value of 2.26 eV for AgNPs was found to be effective for rapid photocatalytic degradation of all the three dyes. The degradation process was observed to follow pseudo first order kinetics.

Photocatalytic degradation of non-ionic, anionic, and cationic surfactants: from batch experiments through equilibrium/kinetic study to ecotoxicology analysis

Surface-active compounds constitute a group of important and widespread environmental pollutants. Among different methods used for their treatment, photocatalytic degradation is a promising and efficient solution. Nevertheless, the exact outcome of photodegradation of surfactants may be difficult to predict in case of concentrations used at the industrial scale and considering that the associated mechanism involves radicals which may potentially result in the formation of toxic by-products. In consequence, the aim of this study was to analyze the catalytic photodegradation of three groups of surfactants (three structurally diverse representatives of cationic, anionic, and non-ionic surfactants). Nanoparticles of zinc oxide were synthesized and used as a photocatalyst. The efficiency of photodegradation ranged from 93 to 100% at 10 mg/L, from 38 to 94% at 100 mg/L, and from 15 to 66% when the surfactants were supplied at 1000 mg/L, and the results depended on the structure of the compound subjected to treatment. Subsequent investigation of kinetics revealed that Freundlich, Langmuir or Dubinin-Radushkevich isotherms may be used to describe the adsorption of surfactants (1–65%) and allowed to establish the following order of reactivity: cationic > non-ionic > anionic. Subsequent LC–MS/MS studies of the residues were the basis for identification of photodegradation products for each respective compound. Ultimately, due to the fact that treated graywater is often used as potable water, the phytotoxicity of the degradation products was tested toward sorghum. It was established that in the majority of cases the treatment was efficient (in some cases stimulation of plant growth compared to control samples was observed), whereas an increase in toxicity was observed in case of two cationic surfactants (CTAB and benzalkonium chloride). Overall, the results presented in this study support the application of photocatalytic degradation as an efficient solution for treatment of surfactant-rich effluents.

Robust iron-doped manganese oxide nanoparticles from facile fabrication to photo-catalytic degradation application of binary dyes mixture

The manganese oxide (MnO2 and iron-doped manganese oxide (Fe–MnO2) nanoparticles (NPs) with reduced band gap (Eg) were fabricated through the co-precipitation process. They used to degrade Indigo Carmine (IC) and Rhodamine B (RB) binary mixture in an aqueous medium under solar light irradiation. From FT-IR, the twisting modes of the Mn–O bond and the stretching vibrations of the Fe–Mn–O2 bond were confirmed from the peaks observed at 480 cm−1,584 cm−1,675 cm−1, and 900 cm−1, 1150 cm−1, and 1200 cm−1 respectively. The MnO2 has an optical band gap of 3.2 eV, which was decreased to 3 eV in Fe–MnO2. The zero charge (PZC) point was 8 for Fe–MnO2 and 7 for MnO2. The BET surface area for Fe–MnO2 was 398 m2/g, relatively higher than MnO2 particles, having a surface area of 384 m2/g. The average crystallite sizes calculated from Scherer formulae were 37 nm for MnO2 and 31 nm for Fe–MnO2 NPs. SEM confirmed the irregular morphology of the prepared particles. It was analyzed that agglomeration occurs in MnO2 than the Fe–MnO2. The maximum degradation of IC dye was 99%, and that of RB was 98% at the optimum conditions. The data were best fitted to second-order kinetics.

Characterization of ZnO/rGO Nanocomposite and Its Application for Photocatalytic Degradation

Zinc oxide (ZnO) nanorods (NRs) with reduced graphene oxide (rGO) were successfully synthesized using a hydrothermal method with an additional spray coating. This paper focuses on the effect of rGO coating on charge transfer and interaction between ZnO and rGO that remarkably contributes to the enhancement of the electrical and optical properties of ZnO-based NRs. The synthesized ZnO/rGO nanocomposite was characterized using FESEM, PL spectroscopy and XPS. FESEM analysis results showed that the surface morphology of the synthesized NRs had a hexagonal rod structure covered with rGO layers on the tip of the rod. The Tauc Plot analysis revealed that the rGO layers reduced the bandgap of ZnO NRs from 3.25 eV to 3.17 eV, where the light absorption increased. The chemical composition, electronic state, and interactions between the elements in the ZnO NRs/rGO nanocomposites were investigated using XPS. The presence of oxygen species due to the rGO deposition layers is indicated by the shift of the peak position toward a greater binding energy. The hybridization of this semiconductor and graphene material reduced the bandgap and lowered the PL emission. Finally, the photocatalytic activity of ZnO NRs/rGO has been studied for methylene blue degradation via oxidation. The results showed that the photocatalytic reaction rate constant of ZnO NRs/rGO > pristine ZnO NRs.

An ab-initio investigation of structural, electronic, optical and elastic properties of novel double Vacancy-ordered perovskite Cs2MoI6 for photocatalytic application

Manipulation of appropriate photocatalyst is a core issue for applications in photocatalytic degradation of contaminants. In this context, the double perovskite Cs2MoI6 exhibit encouraging photocatalytic properties, suggesting it may be useful for photocatalytic water-splitting and contaminants degradation. Here, we have analyzed the structural, electrical, optical, and elastic characteristics of Cs2MoI6 employing first-principles density functional theory computations. According to structural property studied compound is cubic with 7.75Å lattice constant. There have determined through research that the perovskite Cs2MoI6 has mechanical stability and anisotropic elastic characteristics. Upon inspection of its electronic band structure, Cs2MoI6 is originating to be a semiconductor with direct bandgap energy of 1.33eV. With a small effective mass of hole carriers and a narrow bandgap, electrons can easily move to the surface, boosting the photocatalytic rate. The formation of electron-hole pairs upon photon absorption, as predicted by the relevant band edge potential, indicates the substance's capability to splitting water into its constituent H2 and O2 molecules. Our results are predictable to subsidize the improvement of efficient photocatalytic devices for use in degradation of ecological contaminants. Based on the achieved tunable moderate bandgap and noble optical absorption in the UV region, the Cs2MoI6 proposed for utilization in various thermoelectric, electrical, optical and optical applications, particularly in novel energy generation applications.

Utilization of the copper recovered from waste printed circuit boards as a metal precursor for the synthesis of TiO2/magnetic-MOF(Cu) nanocomposite: Application in photocatalytic degradation of pesticides in aquatic solutions

In this study, a number of leaching solutions (H2SO4, CuSO4 and NaCl) and an electrochemical method were used together for the separation of Cu from waste printed circuit boards. Secondly, the magnetic-MOF(Cu) was synthesized using the Cu recovered from waste printed circuit boards. Thereafter, TiO2/mag-MOF(Cu) composite was prepared and its photocatalytic activity was assessed in the photo degradation of two prominent organophosphorus pesticides, namely malathion (MTN) and diazinon (DZN). The catalytic structure of the MOF-based composite was fully characterized by various analyses such as XRD, SEM, EDAX, FT-IR, VSM and UV–vis. The obtained analyses confirmed the successful synthesis of TiO2/mag-MOF(Cu) composite. The synthesized composite exhibited highly efficient in the degradation of both pollutants under the following conditions: pH 7, contaminant concentration 1 mg/L, the catalyst dosage of 0.4 g/L, visible light intensity 75 mW/cm2 and reaction time of 45 min. First order kinetic model was best suited with the experimental results (R2: 0.97–0.99 for different MTN and DZN concentrations). Trapping studies revealed that superoxide radicals (O2•−) played an important role during the degradation process. Furthermore, the catalyst demonstrated a superb recovery as well as high stability over five cyclic runs of reuse. In addition, the total organic carbon (TOC) analysis showed over 83% and 85% mineralization for MTN and DZN, respectively. The combined system of TiO2/mag-MOF(Cu)/Vis also exhibited a great level of efficiency and feasibility in the treatment of tap water and treated wastewater samples. It is concluded that TiO2/mag-MOF(Cu) could be used as an excellent catalyst for the photodegradation of MTN and DZN in aqueous solution.

Fabrication of LaCrO3@SiO2 Nanoparticles Supported with Graphene-Oxide for Capacitive Energy Storage and Photocatalytic Degradation Applications

Fabrication of LaCrO3@SiO2 Nanoparticles Supported with Graphene-Oxide for Capacitive Energy Storage and Photocatalytic Degradation Applications

Enhanced Visible Light Photocatalytic Activity of g-C3N4/SiO2@TiO2 Heterojunction Fabricated by Hydrothermal Synthesis

Photocatalysts that can utilize sunlight energy have attracted attention. In this study, g-C3N4 and mesoporous SiO2@TiO2 particles were mixed by hydrothermal synthesis. g-C3N4 was made by a simple method of directly heating melamine. Mesoporous SiO2@TiO2 was prepared using the stover method. These two types of particles were then mixed by hydrothermal synthesis. Hydrothermal synthesis reduced the size of the g-C3N4 particles, and they bound more closely with the TiO2 particles. The degradation of methylene blue dye by visible light was performed to evaluate the organic degradation of the mixed particles. In addition, the mixed particles were formed into a thin film by the spin-coating method. The film's methylene blue degradation performance and the film's power generation performance in a battery were evaluated. The film showed high convenience in the practical application of photocatalytic degradation of organic pollutants because it can be easily separated from the treated liquid after organic matter degradation.

Construction of covalent organic framework nanozymes with photo-enhanced hydrolase activities for colorimetric sensing of organophosphorus nerve agents

Construction of covalent organic frameworks (COFs)-based nanozymes is of great importance for the extensive applications in catalysis and sensing fields. In this work, a two-dimensional COF (DAFB-DCTP COF) was fabricated via Knoevenagel condensation reaction. The integration of catalytically active sites of pyridine groups into the donor-acceptor (D-A) conjugated skeleton endows DAFB-DCTP COF with both hydrolytic and photosensitive properties. The DAFB-DCTP COF can be utilized as an artificial enzyme with selective and photo-enhanced catalytic efficiency, facilitating its application in photocatalytic degradation of hydrolase substrates (p-nitrophenyl acetate, pNPA) by nucleophilic reaction and further realizing colorimetric detection of the nanozyme inhibitor of organophosphorus nerve agent (diethyl cyanophosphonate, DCNP). The distinct color changes could be distinguished by naked eyes even at a low DCNP concentration, and the versatile smartphone analysis featured with reliability and simplicity. For the first time, the COFs' intrinsic hydrolase activity depending on their structural characteristics was investigated in synergy with the photosensitive performance originating from their photoelectric features. The present contribution provides a promising direction towards construction of colorimetric sensing platform based on the regulation of COFs’ non-oxidoreductase activity under visible light irradiation.

Spray coated of newly La-doped SnS2 thin films for photocatalytic degradation application

In the present study, we present a comprehensive investigation on the synthesis and thorough characterization of La (2 and 4 at. %)-doped 2D-SnS2 thin films, which were prepared by a spray-coating method with a clear molecular ink. These thin films were specifically targeted for their potential application in photodegradation. The impact of La doping on the structural, morphological, mechanical, and electrical properties of the thin films was analyzed using a range of appropriate techniques. Additionally, the mechanical properties were assessed through Vickers micro-indentation. The results indicate that the pristine SnS2 films predominantly exhibit a preferred (101) crystal planes, while the introduction of La doping results in the appearance of a secondary Sn2S3 phase. The bandgap of the films was measured to range from 2 eV to 2.22 eV. Moreover, the thermoelectric power analysis revealed that the films exhibit n-type characteristics, and the mechanical properties showed an increase in hardness with La doping. Notably, the photocatalytic degradation rate was found to be 58.2%, 60.27%, and 62.92% for pristine SnS2, La (2 at.%)-SnS2, and La (4 at.%)-SnS2, respectively, when tested against Malachite green dyes under visible light. This enhancement in degradation efficiency can be attributed to the presence of La3+ ions, which promote electron-hole pair generation.

Preparation of Oxygen-Doping Nongraphitic Carbon Nitride via Efficiency Exfoliation for the Application of Photocatalytic Degradation.

E-OLCN photocatalyst was synthesized by oxygen doping of low molecular weight carbon nitride (LCN) with ethanol solvent stripping. The enhanced light absorption, fast electron transport rate, and photogenerated carrier separation efficiency of E-OLCN leads to the excellent photocatalytic degradation performance compared with the original materials. The synergistic effect of oxygen doping and ethanol solvent stripping plays a significant role for the modulation of electronic and structural properties of the prepared catalysts. Methyl orange (MO) and rhodamine B (RhB) are chosen as typical pollutants for the application of photocatalytic degradation. The E-OLCN sample exhibits outstanding photocatalytic degradation performance, where the rate constant k (1 × 10-2 min-1) of E-OLCN (1.68) is 2.9 times than that of O-LCN (0.58) and 8.8 times than that of pristine LCN (0.19) for MO. Moreover, modulated E-OLCN shows good stability after cycling experiments and the activity still achieved 90%. The detailed mechanism for MO degradation was proposed with the technical support of liquid chromatography-mass spectrometry (LC-MS) and electron spin resonance (EPR). The superoxide radical (·O2-) is the main active species and the MO molecule could be decomposition completely.

Synthesis of molybdenum trioxide/graphite carbon nitride heterojunction modified by biomass carbon dots and its application in photocatalytic degradation of methylene blue

Herein, a hexagonal molybdenum trioxide/graphite carbon nitride heterojunction modified by biomass carbon dots was synthesized by a simple one-pot method and successfully applied to the degradation of methylene blue as a photocatalyst. It was confirmed that under optimal compounding conditions, graphite carbon nitride and hexagonal molybdenum trioxide combined to form a heterojunction, and the coupling interface accelerated the charge transfer efficiency. The modification of supplementary biomass carbon dots can improve the photocatalytic activity of the photocatalyst for the degradation of methylene blue. The proposed heterojunction shows better photocatalytic activity than bulk graphite carbon nitride and has good reusability and stability. After irradiation with simulated visible light for 1 h, the degradation rate of methylene blue by the heterojunction reached 67 %, which was 2.7, 2.6 and 5.8 times higher than that of bulk graphite carbon nitride, pure hexagonal molybdenum trioxide and pure carbon dots, respectively.

Green synthesis of zinc oxide nanoparticles from Rhododendron arboreum extract and their potential applications in photocatalytic degradation of cationic dyes malachite green and Fuchsin basic dye

Green synthesis of zinc oxide nanoparticles from Rhododendron arboreum extract and their potential applications in photocatalytic degradation of cationic dyes malachite green and Fuchsin basic dye

Facile synthesis of ZnO/Ag/g-C3N4 nanocomposites for multiple applications in photocatalytic degradation and photoactivated NO2 sensing

It is important to seek effective strategies to fabricate nanomaterials with multi-functionalities in noxious gas detection and poisonous waste treatment. Herein, Ag nanoparticles and g-C3N4 nanosheets co-modified ZnO heterostructure was synthesized via a one-step polymer-network gel method, which is used as both photocatalyst and sensing material. Being a visible-light-driven photocatalyst, the ternary ZnO/Ag/g-C3N4 composite produced 100 % Rhodamine B degradation within 30 min with good cycling stability. Besides, the gas sensor based on ZnO/Ag/g-C3N4 exhibited superb room-temperature sensing performance under neutral light excitation, with a response value of 15.3–5 ppm NO2 and a lower detection limitation. The excellent performance was mainly attributed to the significantly enhanced visible-light absorption as well as effectively suppressed charge recombination because of the synergism between the individual components. Moreover, the formation of g-C3N4 nanosheets during thermal oxidation etching plays a critical role in improving the surface area and enriching the surface oxygen vacancies. Thus, this work provides novel insights for the synthesis and multi-applications of ZnO/Ag/g-C3N4 heterostructure with high performance.

Fabrication of unconventional S-scheme NiAl LDH/Ag6Si2O7 heterojunction photocatalysts: outstanding photocatalytic performance and photocatalytic mechanism for tetracycline degradation

Tetracycline (TC) was photocatalytically degraded using a series of NiAl LDH/Ag6Si2O7 (LAS) catalysts that were manufactured by dotting Ag6Si2O7 (ASO) particles on the surface of NiAl LDH 3D nanospheres. In terms of TC degradation, LAS had the superior photocatalytic performance, and its clearance of TC was 2.85 times and 1.91 times greater than that of pure NiAl LDH and Ag6Si2O7, respectively. The separation of photogenerated electron-hole pairs has been enhanced since the LAS hybrid photocatalyst has more positive sites. Additionally, it was established through the analysis of the photocatalytic mechanism that the principal active participants in the reaction were •O2- and h+. In order to recover the degradation-stage intermediates, two additional TC degradation techniques were supported by LC-MS and 3D EEM assays. Additionally, the LAS photocatalytic substance has outstanding photocatalytic productivity and stability. This study has offered a fresh perspective on how to construct S-scheme heterojunctions, providing a perfect orientation for the application of photocatalytic degradation of contaminants.

Preparation and characterizations of TiO2/ZnO nanohybrid and its application in photocatalytic degradation of tetracycline in wastewater

The photodegradation of tetracycline antibiotics (TC) in an aqueous solution, using the TiO2 nanoparticles, ZnO microparticles, and TiO2/ZnO composite under the UV lamp in a continuous reactor, was performed. The effects of different parameters, such as the initial TC concentration, medium pH, ratio of each photocatalyst, and the flow rate were comprehensively studied. SEM, EDX, and XRD characterization techniques were employed to study the morphology and structure features of the prepared composite. The results revealed that a more significant amount of TC is not easily removed from wastewater. Furthermore, by increasing the pH of the medium to 11, the efficiency of TC degradation was increased, while the amount of removal remained stable at higher pH values. As the flow rate increased up to 190 mL/min, the removal efficiency increased; however, at higher flow rates, lower efficiency was obtained. Moreover, using multivariate analysis and response surface methodology (RSM), a model for removing TC and the effect of experimental parameters on removal efficiency was proposed. The optimal conditions using the RSM method were found to be the reduction efficiency of 78.94 % in pH = 11 (flow rate of 132 mL/min, and TiO2 concentration of 323 mg) and reduction efficiency of 75.89% in pH = 9 (flow rate of 143.19 mL/min and TiO2 concentration of 312.73 mg).

Optoelectronic, photocurrent sensitivity and photocatalytic dye degradation behaviour of spray deposited Cr doped SnO2 thin films

Undoped and SnO2:Cr doped thin films (Cr: 0.25, 0.50, 0.75 and 1 wt%) were deposited by economically home-made spray pyrolysis method. The characteristic behaviour of the deposited films was studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Photoluminescence (PL), Ultraviolet–visible (UV–vis.) spectroscopy, Current-Voltage (I–V) and photocatalytic studies. The XRD analysis confirms the tetragonal rutile structure of SnO2 with predominant orientation along the (2 1 1) plane and the decrease in crystallite size from 48 to 30 nm by Cr-doping. The EDAX and XPS studies reveal the elements and its chemical state of Sn, O and Cr. The SnO2:Cr thin films exhibit an 85% average optical transmittance in the visible region of the electromagnetic spectrum. The SEM micrographs clearly show the well-defined grains with boundaries, and it is evident that grain size drastically reduces from 155 nm to 48 nm as a function of Cr-doping. Photoluminescence analysis confirms the defect-related emission (360 nm, 440 and 490 nm). The photocatalytic activity of all thin films is assessed using malachite green (MG) dye under UV light irradiation. 0.75 wt% Cr-doped SnO2 film shows improved photocatalytic performance (60.37%) than undoped thin film (32.03%). The I–V characteristics of undoped and SnO2:Cr thin films are performed in visible light, showing photo-linear response behaviour. The highest figure of merit (FOM) obtained for SnO2:Cr (0.75 wt%) thin film is 7.07 × 10−6 Ω−1. The obtained values of the FOM and photocatalytic performance are discussed in the context of the suitability of these materials for transparent and conducting window materials in solar cells and photocatalytic degradation applications.

One-Step Hydrothermal Synthesis of Cu2ZnSnS4 Nanoparticles as an Efficient Visible Light Photocatalyst for the Degradation of Congo Red Azo Dye.

A hydrothermal method was successfully employed to synthesize kesterite Cu2ZnSnS4 (CZTS) nanoparticles. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and optical ultraviolet-visible (UV-vis) spectroscopy were used for characterization of structural, chemical, morphological, and optical properties. XRD results confirmed that a nanocrystalline CZTS phase corresponding to the kesterite structure was formed. Raman analysis confirmed the existence of single pure phase CZTS. XPS results revealed the oxidation states as Cu+, Zn2+, Sn4+, and S2-. FESEM and TEM micrograph images revealed the presence of nanoparticles with average sizes between 7 nm to 60 nm. The synthesized CZTS nanoparticles bandgap was found to be 1.5 eV which is optimal for solar photocatalytic degradation applications. The properties as a semiconductor material were evaluated through the Mott-Schottky analysis. The photocatalytic activity of CZTS has been investigated through photodegradation of Congo red azo dye solution under solar simulation light irradiation, proving to be an excellent photo-catalyst for CR where 90.2% degradation could be achieved in just 60 min. Furthermore, the prepared CZTS was reusable and can be repeatedly used to remove Congo red dye from aqueous solutions.

Effect of Calcination Temperature on Synthesis of g-C3N4 and its Application in Photocatalytic degradation of Methylene Blue Dye

Effect of Calcination Temperature on Synthesis of g-C3N4 and its Application in Photocatalytic degradation of Methylene Blue Dye