Eco-friendly Photocatalyst Research Articles

Noble-Metal-Free ZnII-Anchored Pyrene-Based Covalent Organic Framework (COF) for Photocatalytic Fixation of CO2from Dilute Gas into Bioactive 2-Oxazolidinones.

Photocatalytic conversion of CO2 into value-added chemicals offers a propitious alternative to traditional thermal methods, contributing to environmental remediation and energy sustainability. In this respect, covalent organic frameworks (COFs), are crystalline porous materials showcasing remarkable efficacy in CO2 fixation facilitated by visible light owing to their excellent photochemical properties. Herein, we employed Lewis acidic Zn(II) anchored pyrene-based COF (Zn(II)@Pybp-COF) to facilitate the photocatalytic CO2 utilization and transformation to 2-oxazolidinones. Notably, Zn-COF displayed absorption of visible light, with an optimal band gap of 1.8 eV, effectively catalyzing light-mediated functionalization of propargylic amines to 2-oxazolidinones under green conditions. Detailed experimental and theoretical mechanistic investigations demonstrated that light plays a crucial role in enhancing the efficacy of the photocatalyst, as it activates inert CO2 molecule to radical anion and thereby, lowers the energy barrier for its subsequent cyclization reaction with propargylic amine. Additionally, Zn-COF demonstrates promising catalytic performance utilizing dilute gas as the CO2 source. This is the first report regarding noble metal-free, Zn-COF exhibiting excellent photocatalytic carboxylative cyclization of CO2 with propargyl amines to prepare 2-oxazolidinones using dilute gas (13% CO2). This study offers a new direction for rationally constructing noble metal-free eco-friendly photocatalysts for achieving CO2 fixation reactions under eco-friendly conditions.

Sorghum grain as a bio-template: emerging, cost-effective, and metal-free synthesis of C-doped g-C3N4 for photo-degradation of antibiotic, bisphenol A (BPA), and phenol under solar light irradiation.

Due to the industry's rapid growth, the presence of organic pollutants, especially antibiotics, in water and wastewater resources is the main concern for wildlife and human health. Therefore, these days, a significant challenge is developing an efficient, sustainable, and eco-friendly photocatalyst. Natural biological models have numerous advantages compared to artificial model materials. Biological models with unique multi-level structures and morphology can be used to create porous bio-templates to produce hierarchical materials. So, in this work, for the first time, this was achieved by using sorghum grain seeds as a bio-template (natural waste material) and urea as a precursor, through a simple and environmentally friendly method. We believed that natural waste materials with high carbon atom content could be used as both a carbon doping agent and a bio-template, thus improving the physical and optical properties of the resulting materials. In comparison to previous studies on the synthesis of C-doped g-C3N4, our work offers a greener and more cost-effective approach to synthesis, while also reducing waste material. We succeeded in the photo-degradation of a series of organic pollutants such as phenol, bisphenol A (BPA), and amoxicillin (AMX) in an aqueous solution under solar light illumination.

Cyanobacterial hydrothermal carbonization carbon as photocatalyst for selective aerobic oxidation of cyclohexane

The exploration of catalyst preparation techniques that incorporate environmental-friendly methodologies has consistently been the focus of scientific inquiry within the field of green synthesis of oxygen-containing organic chemicals. Herein, a metal-free hydrothermal carbonation carbon (HTCC) has been prepared utilizing cyanobacterial biomass produced during a water bloom in a freshwater lake. The HTCC produced is capable of performing photocatalytic selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA oil) under ambient conditions. The use of cyanobacterial biomass allows for the efficient preparation of HTCC, which exhibits a conversion rate of cyclohexane that is 4.1 times of HTCC prepared with alternative carbon sources (glucose). The selectivity to KA oil over the samples are almost 100%. Characterizations and analysis reveal that cyanobacteria can lead to self-doping of nitrogen and hydrophobicity of the resulting HTCC, while sulfuric acid etching endow it with more photoactive sp2 hybridized structure units that contribute to a higher photogenerated carrier separation efficiency. The suitable band structure enables the cyanobacterial HTCC to produce superoxide radicals to oxidize cyclohexane. These findings are of great significance for the development of eco-friendly photocatalysts and the utilization of biomass resources.

Cu-Doped InP Quantum Dots: Charge Carrier Dynamics and Photocatalytic Hydrogen Production

Harnessing solar energy for photocatalytic hydrogen production represents a promising path towards sustainable energy solutions. Quantum dots (QDs) offer distinct advantages over traditional metal oxides, including boasting tunable bandgaps and enhanced light absorption in the visible spectrum. In the present study, InP QDs were chosen as the backbone for photocatalytic hydrogen production, leveraging their environmentally friendly properties and tunable bandgap, which extends into the near-infrared region. By introducing Cu dopants to modify the carrier dynamics of InP QDs, the localization of photogenerated charge carriers was effectively enhanced, resulting in improved photocatalytic performance of InP QDs. This study underscores the potential of Cu-doped InP QDs as efficient and eco-friendly photocatalysts for solar-driven hydrogen production. Time-resolved photoluminescence spectroscopy was employed to analyze the quantitative impact of Cu dopants on the interfacial charge dynamics, offering insights into optimizing the charge transfer processes of QDs for enhanced solar hydrogen production efficiency.

3D-micro-flower like [formula omitted] nanoplate solid solution: A facile and rapid room-temperature synthesis with excellent photocatalytic decomposition of antibiotics in water

This research addresses the environmental threat posed by residual antibiotics in water and explores the potential of the photocatalytic process as an eco-friendly solution for antibiotic wastewater treatment. Here in, a series of BiOBr1−xClx nanoplate solid solutions with varied Br:Cl molar ratios were synthesized through a simple co-precipitation method. These solid solutions exhibited superior visible-light-driven photocatalytic activity compared to pristine BiOCl and BiOBr. Notably, the BiOBr0.25Cl0.75 sample demonstrated exceptional performance, achieving 89 % and 99 % degradation efficiency for ciprofloxacin (CIP) and tetracycline hydrochloride (TCH), respectively, within 20 min under optimum conditions. The outstanding performance is attributed to factors such as a large specific surface area, suitable morphology and band gap, effective separation of photo-generated electron-hole pairs, and the presence of meso-size pores in the structure. Thermodynamic studies confirmed the exothermic and spontaneous nature of the photocatalytic reactions. The proposed degradation pathway of CIP and TCH, along with the photocatalytic mechanism, is elucidated. The solid solution, BiOBr1−xClx, exhibits facile recyclability, robust stability, and excellent adaptability to actual aquatic environments, establishing its potential as a promising eco-friendly photocatalyst for antibiotic pollution control.

Different metal-doped NiO nanoparticles for sunlight-mediated degradation of low-density polyethylene microplastic films.

Due to the widespread use and incorrect handling of plastics, we need to find a practical and effective way to eliminate plastic waste from the environment. Different metal-doped nickel oxide (DMD-NiO) nanoparticles (NPs) were synthesized using a sol-gel technique and were used to degrade low-density polyethylene (LDPE) microplastic (MP) films when exposed to sunlight. The optical and structural properties of sol-gel method synthesized materials were investigated using a variety of characterization methods (Fourier transform infrared (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray diffractometer (XRD) analysis, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, and thermogravimetric analysis (TGA). Degradation study results suggest that the photocatalytic activity of DMD-NiO-LDPE nanocomposites (NCs) films was greater than that of pure LDPE and undoped NiO-LDPE films. Because of their increased optical absorption and efficient suppression of photo-produced charge carriers' recombination, the DMD-NiO NPs showed higher photocatalytic degradation of LDPE films. Thus, LDPE films with 2% wt Fe-NiO (iron-doped nickel oxide) nanomaterials showed a degradation of around 38.16% among DMD-NiO-LDPE NCs films under visible light over a short period of 30 days (240 h). The formation of carbonyl groups in the degradation product of LDPE was confirmed by Fourier transform infrared (FT-IR) analysis. When compared to the original LDPE film, the Fe-NiO-LDPE NCs films showed a significant decrease in crystallinity and carbonyl indexes, as much as 8.4% lower. The current project proposes the development of eco-friendly photocatalysts using a sol-gel technique for combating MP pollution in the environment.

Evaluating the Photocatalytic Activity of Green Synthesized Iron Oxide Nanoparticles

Water pollution from dyes is a major environmental challenge, demanding advanced materials for efficient degradation. In this study, we synthesized iron oxide nanoparticles (IONPs) using an aqueous extract of Senegalia catechu leaves and evaluated their photocatalytic activity in methylene blue (MB) dye degradation under sunlight irradiation. The IONPs were characterized by UV-visible spectroscopy (UV–vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). XRD pattern showed a highly crystalline structure with an average crystallite size of 34.7 nm, while SEM images revealed predominantly spherical particles with uneven surface texture. Photocatalytic efficiency exceeded 80% MB dye degradation after 120 min of sunlight exposure. Optimization of catalyst dose, pH, dye concentration, and other parameters is essential for maximizing degradation efficiency. The IONPs demonstrated reusability over four degradation cycles, retaining effective photocatalytic performance. This study underscores the potential of green-synthesized IONPs as eco-friendly photocatalysts for wastewater treatment and environmental remediation.

Synergistic role of indium doping and g-C3N4 reinforcement in boosting the visible light-triggered rhodamine B and diclofenac sodium salt degradation over rare earth molybdate

Designing and fabricating cost-efficient and eco-friendly photocatalysts for removing organic pollutants from wastewater streams is a crucial research objective for effectively managing industrial effluents to tackle environmental sustainability issues. In this study, we prepared bare cerium molybdate (Ce2(MoO4)3, M1) and indium-doped cerium molybdate (In- Ce2(MoO4)3, M2) photocatalysts via a hydrothermal method. We then synthesized a nanocomposite of In- Ce2(MoO4)3 (M3) with the promising material graphitic carbon nitride (g-C3N4) using an ultrasonication approach. The synthesized photocatalysts were effectively applied to degrade the Rhodamine B dye and diclofenac sodium salt (a drug) from synthetic industrial wastewater through a photocatalysis approach. The impact of indium (In3+) doping on the bare (Ce2(MoO4)3 and the strong interaction between the (In-Ce2(MoO4)3 and g-C3N4 nanosheets were analyzed through physical and electrochemical techniques, including SEM, EDS, XRD, FTIR, UV–Vis spectroscopy, and EIS analysis. The comprehensive photocatalytic degradation of dye and the drug via first-order kinetic parameters under visible light irradiation for all the prepared catalyst samples was evaluated. The nanocomposite In-Ce2(MoO4)3/g-C3N4 exhibited excellent photocatalytic activity, degrading the maximum amount of RhB dye and drug (RhB:96 %, drug:87 %) in 90 min with a higher rate constant (k) compared to In-Ce2(MoO4)3 (RhB:69 %, drug:56 %) and Ce2(MoO4)3 (RhB:56 %, drug:38 %). Furthermore, the In-Ce2(MoO4)3/g-C3N4 samples produced a 7-fold and 3-fold increase in transient photogenerated current response compared to pristine Ce2(MoO4)3 and In-Ce2(MoO4)3 samples, respectively. These findings pave the way for synthesizing an economical, versatile, and efficient In-Ce2(MoO4)3/g-C3N4 photocatalyst to eliminate pollutants from industrial wastewater streams and boost environmental sustainability.

Constructing AlOOH-PVA/ZIF-67/AgCl/Ag composite membrane for the efficient photodegradation of organic pollutants under visible light irradiation

This study effectively fabricated photocatalytic membranes (∼5 cm diameter) assembled by γ-AlOOH-PVA (BOP) decorated heterostructural ZIF-67/AgCl/Ag composites by combing seeded secondary growth and photoreduction methods. First, the ZIF-67-seeded BOP membrane was shaped in a petri dish, followed by submerging in a 2-methylimidazole ligand for secondary growth to obtain the BOP/ZIF-67 membrane. Next, AgCl/Ag was formulated on the membrane by dipping it in an AgNO3 solution, followed by a photoreduction under visible LED light, resulting in a BOP/ZIF/AgCl/Ag membrane. The characterization showed that the membrane contained heterostructures of ZIF-67/AgCl/Ag anchored onto the BOP membrane. The BOP/ZIF/AgCl/Ag composite membranes exhibited enhanced light absorption and appeared the localized surface plasmon resonance (LSPR) of Ag0, giving it a bandgap energy of ∼2.10 eV. Photodegradation under visible LED light irradiation showed that the BOP/ZIF/AgCl/Ag membrane efficiently removed tetracycline (TC) and Rhodamine B dye (RhB) with corresponding degradation efficiency of ∼99% (90 min) and ∼95% (140 min), giving reaction rates of ∼0.046 min−1 and 0.019 min−1, respectively. The photocatalytic mechanism and photodegradation pathways analyses provided insights into the degradations of organic pollutants. Significantly, the designed BOP/ZIF/AgCl/Ag membrane quickly recovered from the solution and was of good durability. The study provided an effective strategy for constructing heterostructural ZIF-67/AgCl/Ag composite membranes, which are efficient and eco-friendly photocatalyst materials.

Visible-light-driven F/C co-doping g-C3N4 nanosheets for efficient hydrogen evolution: Charge redistribution on C4 delocalized large π bond

Developing photocatalytic hydrogen evolution technology based on graphitic carbon nitride (g-C3N4, CN) has emerged as a potential solution for the future energy shortage in recent years. Herein, carbon (C) and fluorine (F) co-doping graphitic carbon nitride nanosheets (CFCN) were synthesized via a one-pot co-thermal method without introducing any metal element. Exceptional hydrogen production activity (3.87 mmol/h/g) was achieved by CFCN under visible light irradiation, which was 4.2-fold increase compared to the pristine CN. It could be attributed to the large specific surface area (51.59 m2/g) and efficient mass transfer facilitated by the porous sheet-like morphology of CFCN. Additionally, the modification of the band structure and internal charge redistribution were investigated via density functional theory (DFT) calculations, which confirmed there was a unidirectional and fast electron transfer channel from N through the C4 delocalized large π bond to F. This creative research uncovered the pivotal role of F/C co-doping in enhancing photocatalytic hydrogen evolution efficacy, offering cutting-edge insights into the design of sustainable and eco-friendly photocatalysts based on metal-free CN.

Fabrication of eco-friendly NiFe2O4 nanocatalysts via plant extract-mediated synthesis: Kinetic and mechanistic insights into photocatalytic degradation of an anthraquinone dye and tetracycline antibiotic

The escalating peril of organic pollutant contamination in water, encompassing dyes and pharmaceuticals, requires the formulation of remediation approaches that are both sustainable and effective. This study addresses this challenge by exploring a bioinspired synthesis route for nickel ferrite nanoparticles (NiFe2O4 NPs) utilizing plant extracts. This eco-friendly approach eliminates the use of hazardous chemicals, promoting environmental sustainability compared to conventional methods. The plant extracts of Psidium guajava and Terminalia chebula were employed for the fabrication of NiFe2O4 NPs and the as-synthesized materials i.e. NiFe2O4 from Psidium guajava and NiFe2O4 from Terminalia chebula, were utilized for the photocatalytic degradation of Deep Blue and Tetracycline from aqueous systems under visible light illumination. The photocatalytic studies revealed the excellent potential of both the catalysts towards the efficient removal (>93 %) of model pollutants. The mechanistic elucidation of the developed system revealed the primary participation of hydroxyl radicals in the Fenton driven process. Furthermore, the developed materials exhibited reusability till multiple degradation cycles suggesting its potential applicability in real water systems. Comprehensively, this work paves the way for a sustainable idea of wastewater treatment, armed with nature inspired and eco-friendly photocatalysts.

Tailoring a decatungstate-incorporated metal-organic framework for light-driven [3+2] cyclization of phenols with olefins

Photocatalytic oxidative [3+2] cycloaddition of phenol-olefin is an economy and green strategy to synthesize 2,3-Dihydrobenzofurans (2,3-DHBs) compared with the thermal catalysis with noble metals under harsh conditions. Thus, it is urgent to design noble metal-free heterogeneous photocatalyst that combined single-electron transfer (SET) and hydrogen-atom transfer (HAT) dual function. Decatungstate [W10O32]4− is considered as an ecofriendly photocatalyst for HAT and SET, but it is commonly used in homogeneous catalysis. Herein, we report CuW10-TIPA as a white-light-activated heterogeneous photocatalyst for synthesizing 2,3-dihydrobenzofurans via [3+2] cycloaddition of phenols with olefins, a crucial step in relevant pharmaceutical structural motifs. The coordination bonds between Cu(I) and TIPA, strong H-bonds between TIPA and [W10O32]4− and anion∙∙∙π interactions between [W10O32]4− and TIPA dramatically promote the separation of photoinduced electron-hole and facilitate the charge transfer among each component. Our approach is characterized by its mildness, scalability, and recyclability. We delve into the discussion on [W10O32]4− anions-mediated C-H bond activation via the HAT pathway, with the cooperation of the photosensitizer TIPA and Cu(I), which enhances absorption in the visible region and narrows the energy band.

Visible-light-driven photocatalytic degradation of tetracycline using citric acid and lemon juice-derived carbon quantum dots incorporated TiO2 nanocomposites

Tetracyclines (TC) are consistently found in aquatic ecosystems, contributing to the development and spread of antibiotic resistance genes and antibiotic-resistant bacteria. This poses adverse effects on aquatic organisms and humans, emphasizing the need for an effective approach to remove these contaminants. TiO2-based photocatalysts hold great potential for efficiently removing TC from water. This study aimed to synthesize TiO2 nanocomposites incorporated with carbon quantum dots (CQDs) derived from both artificial and natural sources. The nanocomposites were characterized using X-ray diffraction, electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption–desorption test. The incorporation of CQDs into TiO2 resulted in the reduction of the band gap energy from 3.17 eV in pure TiO2 to 3.10 eV, broadening the light absorption range, and improving the charge carrier transfer efficiency. Continuously generated electrons led to the production of reactive oxygen species, predominantly •O2–, contributing to TC degradation. Holes and •OH radicals also played a significant role in TC degradation. As a result, CQDs/TiO2 nanocomposites exhibited 91.5 % TC removal under visible light irradiation (λ ≥ 400 nm) for 120 min at pH 8. The active sites of TC molecules were determined through density functional theory calculations, and the corresponding degradation pathways of TC were proposed using liquid chromatography-mass spectrometry. Furthermore, this study attempted to synthesize CQDs using lemon juice, showcasing the potential of these eco-friendly photocatalysts for TC removal. The visible-light-driven degradation of TC by the natural-source-derived CQDs/TiO2 nanocomposites demonstrated their applicability in water treatment to effectively address current environmental challenges.

Box–Behnken Design to Optimize Herbicide Decomposition Using an Eco-Friendly Photocatalyst Based on Carbon Dots from Coffee Waste Combined with ZnBi2O4 and Its Antibacterial Application

Box–Behnken Design to Optimize Herbicide Decomposition Using an Eco-Friendly Photocatalyst Based on Carbon Dots from Coffee Waste Combined with ZnBi2O4 and Its Antibacterial Application

Z-scheme heterojunction photocatalyst formed by MOF-derived C-TiO2 and Bi2WO6 for enhancing degradation of oxytetracycline: Mechanistic insights and toxicity evaluation in the presence of a single active species

In the work, Bi2WO6/C-TiO2 photocatalyst was successfully synthesized for the first time by loading narrow bandgap semiconductor Bi2WO6 on MOF-derived carboxyl modified TiO2. The phase structure, morphology, photoelectric properties, surface chemical states and photocatalytic performance of the prepared photocatalysts were systematically investigated using various characterization tools. The degradation efficiency of oxytetracycline by 6BT Z-scheme heterojunction photocatalyst under visible light could reach 93.6 % within 100 min, which was related to the high light harvesting and effective separation and transfer of photo-generated carriers. Furthermore, the effects of various environmental factors in actual wastewater were further investigated, and the results showed that 6BT exhibited good adaptability, durability and resistance to interference. Unlike most works, the degradation system with a different single active species were designed and constructed based on their formation mechanism. In addition, for the first time, a positive study was conducted on the priority attack sites, intermediate products, and degradation pathways for the photocatalytic degradation of oxytetracycline by a single active species through HPLC-MS and Fukui index calculations. The toxicity changes of intermediate products produced in three different single active species oxidation systems were evaluated using toxicity assessment software tools (T.E.S.T.), Escherichia coli growth experiments, and wheat growth experiments. Among them, the intermediate products formed through O2– oxidation had the lowest toxicity and the main active sites it attacked were the 20C, 38O, 18C, 41O, and 55O atoms with high f+ values in the oxytetracycline molecular structure. This work provided the insight into the role of each active species in the degradation of antibiotics and offered new ideas for the design and synthesis of efficient and eco-friendly photocatalysts.

Overall Spontaneous Water Splitting for Calcium Bismuthate Ca(BiO2)2: Flexible-Electronic-Controlled Band Edge Position and Adsorption-Site-Modulated Bond Strength.

Eco-friendly photocatalysts for water splitting, highly efficient in oxygen/hydrogen evolution reactions, hold great promise for the storage of inexhaustible solar energy and address environmental challenges. However, current common photocatalysts rarely exhibit both H2 and O2 production performances unless some regulatory measures, such as strain engineering, are implemented. Additionally, the extensive utilization of flexible electronics remains constrained by their high Young's modulus. Herein, on the basis of density functional theory calculations, we identify a novel spontaneous oxygen-producing two-dimensional Ca(BiO2)2 material, which can efficiently regulate the electronic structures of the surface active sites, optimize the reaction pathways, reduce the reaction energy barriers, and boost the overall water-splitting activity through biaxial strain modulation. In detail, an unstrained Ca(BiO2)2 monolayer not only possesses a suitable band gap value (2.02 eV) to fulfill the photocatalytic water-splitting band edge relationships but also holds favorable transport properties, excellent optical absorption across the visible light spectrum, and spontaneous oxygen production under neutral conditions. More excitingly, under application of a 7% biaxial tensile strain modulation with an ideal biaxial strength of 32.35 GPa nm, the Ca(BiO2)2 monolayer not only maintains its structural integrity but also exhibits a completely spontaneous reaction for photocatalytic hydrogen precipitation with superior optical absorption. This can primarily be attributed to the substantial reduction of the potential barrier through strain engineering as well as the weakening of bond energy resulting from changes of the adsorption site as calculated by crystal orbital Hamiltonian population analysis. This flexible stretchable electronic modulated the photocatalyst behavior and bond energy of O-Bi and O-Ca interactions, offering outstanding potential for photocatalytic water spontaneous oxygen and hydrogen evolution among all of the reported metal oxides, and is more likely to become a promising candidate for future flexible electronic devices.

Green nanocatalyst for the photocatalytic degradation of organic pollutants in petroleum refinery wastewater: Synthesis, characterization, and optimization

The synthesis of green nanocatalysts is an emerging branch of current nanotechnology due to its numerous advantages, including high efficiency, sustainability, cost-effectiveness, biocompatibility, and eco-friendliness. In this study, a thermal technique was employed to prepare a novel green nanocatalyst (GNC) from the sepals of waste tomato (WT) plants, and this GNC was investigated to determine its efficiency in degrading the chemical oxygen demand (COD) during a photocatalytic process of simulated petroleum refinery wastewater (PRW). The characterization of the waste tomato-green nanocatalyst (WT-GNC) was performed using various techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET) analysis, and Fourier-transform infrared (FTIR) spectroscopy, which revealed that the synthesized WT-GNC possessed an excellent catalytic quality. This work examined the key factors affecting the degradation rates, such as the type of light source (UV or LED) and its arrangement (outside or inside the reactor), aeration rate, pH, catalyst dose, irradiation time, temperature, and initial COD concentration. The WT-GNC degraded 99.9 % of the COD (residual = 1 ppm) under the optimal operating conditions (pH = 7, WT-GNC dose = 0.25 g/L, irradiation time = 90 min, temperature = 25 °C, and initial COD = 1326 ppm) under UV lamps located around the inside of the reactor wall. Ultraviolet (UV) light is highly effective in degrading the COD compared to visible LED lights. The reaction followed the pseudo-first-order kinetic model (R2= 0.998) with k = 0.0367 min−1. The WT-GNC exhibited good reusability and stability and could reduce 76.3 % of the COD after the fifth consecutive cycle. Therefore, this novel GNC can serve as a cost-effective, efficient, stable, and eco-friendly photocatalyst to lower the COD of PRW to meet the World Health Organization (WHO) standards. In addition, it can be recovered and reused several times.

Facile green synthesis route for new ecofriendly photo catalyst for degradation acid red 8 dye and nitrogen recovery

This study novelty is that new photo catalyst prepared from sustainability low cost precursors. Dark red color hydrogel composites have been easily prepared from gelatin biopolymer using a simple sol–gel method. Gelatin doped by cobalt chloride, and silver nanoparticles (SNPs) in the presence of traces amount of sodium dodecyl sulfate surfactant and calcium chloride. Water-insoluble Gelatin composites are thermally stable photocatalysts for the degradation of toxic anionic acid red 8 dye. Promising photodynamic activity confirmed by fluorescence emission at λmax 650 nm. Optical absorption in Vis. light enhanced photo catalytic activity. Silver nanoparticles enhanced crystallinity, and improved optical properties and porosity. Dopants by CoCl2 and silver nanoparticles increased band gap of gelatin composites from (1.82 to 1.95) indicating interfacial charge separation. Low band gaps improved photo catalytic activity. Optical band gaps (Eg) lower than 2.0 eV indicates high catalytic activity in the photo degradation acid red 8 dye using Vis. light, wavelength 650 nm. Percent removal efficiency (%Re) of the dye at 500 ppm initial concentration, pH 1, contact time 30 min., and 0.20 g L−1 dose photo catalyst reached 95%. pH not affects removal efficiency. So, gelatin composites removed AR8 dye by photodegradation mechanism rather than adsorption due to photodynamic activity. Kinetics of photodegradation followed pseudo first order kinetic with rate constant k1 5.13 × 10−2 min.−1 Good electrical conductivity and magnetic properties (effective magnetic moment (µeff 4.11 B.M) improved dye degradation into simple inorganic species. Nutrients NH4+, and NO3− degradation products recovered by using alumina silicate clay via a cation exchange mechanism.

WO3-ZnO as an anti-gastric cancer agent and efficient photocatalyst in the synthesis of substituted benzimidazoles

Benzimidazoles have potential for developing important drugs and fighting cancerous gastric cells. In this study, an efficient and eco-friendly photocatalyst, WO3-ZnO, is used to synthesize some 2-substituted benzimidazoles by condensing aromatic aldehydes with o-phenylenediamine. The synthesis is achieved by irradiation with a commercial green laser. Various techniques like FT-IR, XRD, DLS, UV–Vis, and FE-SEM are used to analyze structure and properties of WO3-ZnO. The nanocatalyst shows excellent reusability and reproducibility. Additionally, cytotoxicity of WO3-ZnO nanoparticles are tested against KATO-III human gastric cancer cells, and MTT assay confirms their cytotoxicity with a significant reduction in cell viability. The cytotoxicity of WO3-ZnO nanoparticles against the performed cell line under in vivo conditions will be directed soon and the obtained results will be compared with the in vitro conditions.

Simultaneous enhancement of the optical absorption, ferroelectric polarization, and photocatalytic activity by designing the Ti/Fe ratio for Bi5Ti3FeO15

Bismuth-contained Aurivillius compounds are potentially low-cost and eco-friendly photocatalysts for organic pollutant degradation because of their unique layered crystal structure. Bi5Ti3-xFe1+xO15 (BTF-x, x = 0–1) photocatalysts were synthesized through the molten salt method. The crystal structure was determined by XRD Rietveld refinements. The phase constitution was found to change from a single 4-layered Aurivillius phase for x = 0 to mixed Aurivillius phases with different layer numbers as x increases. BTF-0.8 and BTF-1 exhibit better frequency stability of dielectric properties. The decrease in the Ti/Fe ratio leads to a monotonic reduction of the bandgap, ascribed to the increase in the octahedral distortion rather than the oxygen vacancy concentration. Surprisingly, the ferroelectric polarization is also improved by decreasing the Ti/Fe ratio and the best ferroelectricity was obtained in BTF-1. The photocatalytic activity of BTF-x catalysts was examined by RhB degradation under visible-light irradiation. The decrease in the Ti/Fe ratio also enhances the photocatalytic activity of BTF-x catalysts. The fastest photodegradation rate was obtained in BTF-1, about 9 times higher than that of BTF-0. Scavenger test studies confirmed that the level of contribution to RhB photodegradation was h+, O2•−, and •OH radicals in descending order. Furthermore, the excellent stability and reusability of BTF-x catalysts were demonstrated by the photocatalytic cycle tests. All the results suggested without introducing hetero elements, adjusting the Ti/Fe ratio was an effective means to narrow the bandgap, improve the ferroelectricity and enhance the photocatalytic activity simultaneously. We hope the present study can be generalized to other Aurivillius phases to acquire much better performance and broader application.