Significant Photocatalytic Activity Research Articles

Highly Active Agro-Waste-Extracted Cellulose-Supported CuInS2 Nanocomposite for Visible-Light-Induced Photocatalysis.

Agro-waste-extracted cellulose-supported CuInS2 nanocomposites were hydrothermally synthesized with significant photocatalytic activity under the influence of cellulose as a polymeric natural support that offers delay in electron–hole life. Delayed recombination process of electrons and holes was perceived by parting of cellulose as a barrier or edge during photochemical reaction, which overall enhances the lifetime of photocatalyst. The photodegradation efficiency over five consecutive cycles along with scavenging studies have been examined for RhB dye under visible light. The boosted photodegradation rate was observed at an optimum amount of cellulose (200 mg), which is ∼10 times higher than pristine CuInS2.

Photocatalytic activity of hierarchical Ti–Zr–ZSM-5 catalysts from attapulgite by MRS

Hierarchical architectures of titanium (Ti)–zirconium (Zr)–zeolite Socony Mobile–Five (ZSM-5) nanocrystalline aggregates were synthesized in a microwave-assisted rapid system. The micro–mesoporous structure and single-site photocatalytic activity of the nanocrystals were developed by using acidized attapulgite (microwave-treated acidized attapulgite) in the precursor solution. The morphology, crystallinity, surface area and porosity of the samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen gas (N2) adsorption–desorption. Results demonstrate that titanium–zirconium–ZSM-5 single-site heterogeneous catalysts persist on the typical framework of mordenite framework inverted structure and present a new spherical aggregate morphology made-up of hexagonal nanocrystals. The synthesis time required is reduced from 12 h to 180 min. The hierarchical nanocrystals have a Brunauer–Emmett–Teller surface area (349·51 m2/g) similar to and a mesopore volume larger than (0·23 cm3/g) those of commercial zeolites. The tetrahedrally coordinated metal oxide (titanium and zirconium) moieties were implanted and isolated in the silica matrices of micro–mesoporous ZSM-5 zeolite, which had a significant photocatalytic activity and reusability for degrading methylene blue dyeing wastewater. As a microreactor, the nanocrystals, with single-site photocatalytic activity, are worthy to be investigated further for potential applications in catalysis for dyeing and wastewater treatment.

Facile and green synthesis of copper nanoparticles loaded on the amorphous carbon nitride for the oxidation of cyclohexane

In this work, copper metallic nanoparticles were successfully immobilized on the surface of the amorphous carbon nitride using the pulse laser ablation in liquid (PLAL) technique in different times of laser irradiation (denoted as Cu-time/a-C3N4). This novel amorphous carbon nitride was fabricated by the in-situ one-step pyrolysis of melamine and pluronic P-123 precursors. The as-synthesized Cu-time/a-C3N4 catalysts, as compared with the bulk Cu-time/g-C3N4, demonstrated remarkable surface structures and catalytic activities. The synthesized catalysts were tested in terms of the oxidation reaction of cyclohexane under two different conditions. The optimized catalyst (Cu-20 min/a-C3N4) showed 25.5% conversion of cyclohexane with 52.0% selectivity to adipic acid in the one-pot aerobic oxidation. Further, the Cu-40 min/a-C3N4 catalyst showed a significant photocatalytic activity in the presence of visible light irradiation for the oxidation of cyclohexane to the ketone-alcohol mixture (KA oil), such that there were 88% conversion and 95% selectivity to the KA oil mixture. In both cases, the nanocatalysts showed the reusability of four times without any loss of catalytic activity.

An innovative transformation of waste toner powder into magnetic g-C3N4-Fe2O3 photocatalyst: Sustainable e-waste management

In this work, we report an ecofriendly and sustainable approach to recycle the waste toner powder enriched in organic residues and magnetic Fe3O4. The direct calcination of waste toner powder at 600 °C ensures the complete decomposition of organic residues and transformation of Fe3O4 into useful magnetic Fe2O3 without any single chemical treatments. We also exploit the e-waste derived Fe2O3 as an iron precursor and thiourea for the fabrication of g-C3N4-Fe2O3 photocatalyst through facile one-step calcination process. The obtained Fe2O3 and g-C3N4-Fe2O3 were characterized by XRD, TGA, SEM-EDS, TEM, BET, XPS, UV–vis. DRS, FT-IR, PL, EIS and VSM. The photocatalytic activity of the g-C3N4-Fe2O3 was evaluated by the degradation of Methyl Orange (MO) and Textile Effluents (TE) under sunlight. The resultant g-C3N4-Fe2O3 exhibited better photocatalytic activity than the Fe2O3 and g-C3N4. Owing to the excellent stability and magnetic separation ability, g-C3N4-Fe2O3 composite displayed superb recyclability without loss of significant photocatalytic activity up to five repeated runs and more significantly, it can be recovered magnetically. This novel e-waste recycling strategy may provide new possibilities for a large-scale and low-cost transformation of waste toner powder into magnetically separable photocatalyst for wastewater treatment.

Ionic‐Liquid‐Assisted Hydrothermal Synthesis of Ag/AgBr for Photodegradation of Imidacloprid under Visible Light

Ag/AgBr photocatalysts are prepared by a ionic‐liquid‐assisted hydrothermal method. The as‐prepared photocatalysts are characterized by scanning electron microscopy, X‐ray powder diffraction, X‐ray photoelectron spectroscopy, Brunauer–Emmett–Teller measurement, and diffuse reflectance spectroscopy. Ag/AgBr exhibits significant photocatalytic activity toward degradation of imidacloprid under visible light. After 9 h, the conversion percentage of imidacloprid reaches 90%. Besides, the cycle performances suggest a good stability of the catalyst. The photocatalytic kinetics indicate that the degradation processes follow pseudo‐first‐order kinetics. According to the fact that electron holes •OH and •O2− greatly promote the photodegradation process, the degradation mechanism is proposed.

Tuber extract of Arisaema flavum eco-benignly and effectively synthesize silver nanoparticles: Photocatalytic and antibacterial response against multidrug resistant engineered E. coli QH4

Metal nanoparticles, synthesized using Phyto-constituents are the most economically and environmentally benign materials ever. Biogenic silver nanoparticles (AgNPs) from three fractions of Arisaema flavum tuber extract were synthesized and characterized by UV–visible spectroscopy, XRD (X-rays diffraction), FT-IR (Fourier transform infrared spectroscopy) TEM (transmission electron microscopy) and EDX (Energy dispersive Microscopy). XRD pattern show the face centred cubic crystalline (Fcc) structure of AgNPs. FTIR spectra confirmed the presence of different Polyphenolic compounds capping the AgNps. UV–visible spectroscopy result confirmed the presence of Ag because of the particular surface plasmon Resonance (SPR) in the area of 400-430 nm. The electron microscope studies revealed the formation of spherical AgNPs with diameter ranging from 12 nm to 20 nm. Strong signals of AgNPs were confirmed with EDX analysis. The antibacterial properties of the AgNPs prepared with various extracts were tested against multi-drug resistant bacteria. Which showed significant antibacterial activity against all the multidrug resistant bacterial strains and especially multidrug resistant engineered E.ColiQH4. AgNPs synthesized by methanolic, Ethyl Acetate and aqueous Extracts of Areseama Flavum exhibited significant Photocatalytic activity to reduce methylene blue. Small size, spherical shape and high dispersion are the key properties due to which the AgNPs are having significant biological and photocatalytic activity. To the best of our knowledge, it is the first report of biogenic AgNPs regarding antibacterial activity against multidrug resistant Engineered E.Coli QH4.

Photocatalytic performance and quick recovery of BiOI/Fe3O4@graphene oxide ternary photocatalyst for photodegradation of 2,4-dintirophenol under visible light

Herein, we immobilized BiOI/Fe3O4 photocatalyst on graphene oxide (GO) using simple co-precipitation method. The formation of BiOI/Fe3O4@GO was ascertained by various analytical techniques viz. FESEM, TEM, XRD, FTIR, UV–Vis, and photoluminescence techniques. SEM and TEM analysis clearly demonstrated the dispersion of BiOI and Fe3O4 on the GO surface. BiOI/Fe3O4@GO photocatalyst exhibited superparamagnetic character and was magnetically separated from the reaction solution. The thickness of BiOI/Fe3O4@GO was less than 17.0 nm. The band gap of BiOI/Fe3O4@GO was 1.78 eV. BiOI/Fe3O4@GO exhibited significant photocatalytic activity for 2,4 dinitrophenol (DNP) degradation under visible light. The reaction conditions were optimized to attain maximum degradation of DNP. The results showed that concurrent occurring of adsorption and photocatalytic processes cause a higher degree of DNP degradation. The DNP was completely converted into CO2 and H2O in 2 h. Enhanced DNP degradation was due to suppression in recombination of photogenerated electron-hole pairs in BiOI. The as-prepared photocatalyst displayed substantial stability and recycling efficiency after 10 catalytic cycles.

Photocatalytic Self-Cleaning Cotton Fabrics Coated by Cu₂(OH)PO₄ under VIS/NIR Irradiation.

In the present work, a mild strategy was employed to obtain cotton fabrics (CFs) coated with Cu2(OH)PO4 (CHP) nanoparticles to achieve self-cleaning property. The phytic acid (IP6) assisted method was employed to synthesize nanoparticles (CHP-IP6). The as-prepared coated cotton fabrics were characterized using the following techniques: Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The CHP-IP6 coated cotton fabrics showed significant photocatalytic activity, excellent photocatalytic stability, and good discoloration of methylene blue (MB) stains when exposed to sunlight, which could have important applications as tablecloths, household apparels, and industrial workwear.

Cost effective green synthesis of NiO nanostructures as highly efficient photocatalysts for degradation of organic dyes

Here, the cost effective green synthesis of nickel oxide (NiO) nanostructures has been reported. The organic capping and/or reducing agents were obtained by extraction from wastes of three different vegetables (cauliflower, potatoes and peas). The extracts of cauliflower and peas peels gave nanowhiskers while the extract of potato peels gave nanorods of NiO, as confirmed by scanning electron microscopy. X-ray diffraction analyses demonstrated the nanocrystalline cubic phase of NiO in all the samples. However, crystallite size varied with the extract of vegetable waste used. Fourier transform infrared analysis helps in identifying different vibrations, particularly Ni–O stretching vibrations, and diffuse reflectance spectra analyses led to the establishment of bandgap energies. The resulting NiO nanostructures were tested for their efficiencies as photocatalysts for Methylene blue degradation. All the three samples have shown significant photocatalytic activities. The exploration in this study clearly demonstrates the very high photocatalytic activities of the synthesised NiO nanostructures, which can be used as competent agents for treatment of wastewater to remove toxic dyes.

A facile and green method for synthesis of ZnFe2O4@CMC as a new magnetic nanophotocatalyst for ciprofloxacin removal from aqueous media

This study aimed to synthesize a ZnFe2O4@carboxymethyl cellulose (CMC) nanophotocatalyst using a simple, facile, and green hydrothermal method for ciprofloxacin (CIP) removal from aqueous solutions. At first, ZnFe2O4@CMC was synthesized using the hydrothermal method, and then it was characterized. To assay the photocatalytic activity of ZnFe2O4@CMC, its ability was investigated in CIP and total organic carbon (TOC) removal by considering the effect of some variables such as initial CIP concentrations (5–30 mg/L), pH (3–11), nanophotocatalyst loading (0.1–0.5 g), and reaction time (20–120 min). The kinetic performance of the process was assessed by the pseudo-first order and Langmuir-Hinshelwood models. The concentration of CIP and TOC in the samples was determined using high performance liquid chromatography and a TOC analyzer, respectively. The influence of competitive compounds was examined on the efficiency of the nanophotocatalyst through its application for a real wastewater sample. Moreover, the reusability and chemical stability of ZnFe2O4@CMC were studied.Advantages of this technique are as follows:•ZnFe2O4@CMC as a high potent magnetically separable photocatalyst is designed by a green, simple, and fast hydrothermal method.•ZnFe2O4@CMC displays significant photocatalytic activity in photocatalytic degradation processes for ciprofloxacin removal.•ZnFe2O4@CMC exhibits good chemical stability and reusability.

A microwave assisted method to synthesize nanoCoFe2O4@methyl cellulose as a novel metal-organic framework for antibiotic degradation

In this research, magnetically separable nanoCoFe2O4@methyl cellulose (MC) as a novel metal-organic framework was designed by a facile, fast, and new microwave-assisted method and then characterized. To assay the photocatalytic activity of nanoCoFe2O4@MC, its ability in metronidazole (MNZ) removal was investigated by considering the effect of some variables such as initial MNZ concentrations (5–20 mg/L), pH (3–11), nanophotocatalyst loading (0.0–0.4 g), and reaction time (15–120 min). The kinetic performance of the process was assessed by the pseudo-first order and Langmuir-Hinshelwood models. The concentration of MNZ was determined by high performance liquid chromatography. The optimal conditions for the maximum MNZ removal efficiency (85.3%) included pH of 11, MNZ concentration of 5 mg/L, photocatalyst loading of 0.2 g, and irradiation time of 120 min. Moreover, the reusability and chemical stability of nanoCoFe2O4@MC were studied. MNZ was successfully degraded at a rate of 77.58% in the fourth run.Advantages of this technique were as follows:•A facile, fast, and new microwave-assisted method was developed to synthesize nanoCoFe2O4@MC as a new nanobiomagnetic photocatalyst.•Pure-phase spinel ferrites, spherical particle morphology with smaller agglomeration, and ferromagnetic nature of nanoCoFe2O4@MC were confirmed.•NanoCoFe2O4@MC displayed a significant photocatalytic activity in the photocatalytic degradation of MNZ; moreover, it was easily separated by a magnet and exhibited good chemical stability.

Stone/Coating Interaction and Durability of Si-Based Photocatalytic Nanocomposites Applied to Porous Lithotypes.

The use of hybrid nanocoatings for the protection of natural stones has received increasing attention over the last years. However, the interaction of these materials with stones and, in particular, its modification resulting from the blending of nanoparticles and matrices, are yet little explored. In this work, the interaction of two nanocomposite coatings (based on alkylalkoxysilane matrices and TiO2 nanoparticles in water and 2-propanol) with two different porous stones is examined in detail by comparing their absorption behaviour and protection performance with those of the respective TiO2-free matrices. It is shown that the protective effectiveness of both matrices is not negatively affected by the presence of TiO2, as the desired water barrier effect is retained, while a significant photocatalytic activity is achieved. The addition of titania leads to a partial aggregation of the water-based matrix and accordingly reduces the product penetration into stones. On the positive side, a chemical interaction between titania and this matrix is observed, probably resulting in a greater stability of nanoparticles inside the protective coating. Moreover, although an effect of TiO2 on the chemical stability of matrices is observed upon UV light exposure, the protective performance of coatings is substantially maintained after ageing, while the interaction between matrices and nanoparticles results in a good retention of the latter upon in-lab simulated rain wash-out.

Synthesis of novel ZnO/carbon xerogel composites: Effect of carbon content and calcination temperature on their structural and photocatalytic properties

This paper reports the development of new ZnO/carbon xerogel composites (XZn w) for photocatalytic applications. The use of black wattle tannin as a precursor to the carbon xerogel aimed at reducing costs and environmental impacts. The composites were characterized by diffuse reflectance spectroscopy (DRS), BET surface area, scanning electron microscopy (FEG-SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), infrared spectroscopy (IR), and X-ray diffraction (XRD). The photocatalytic performance of the materials was evaluated in the decomposition process of methylene blue, a known toxic pollutant. The impacts of the catalyst dosage and calcination temperature on the photocatalytic process were also examined systematically. The X-ray profiles of the XZn w evidenced the existence of the hexagonal structure of the zinc oxide (wurtzite) in the composites. The XPS and XRD analyses confirmed the incorporation of carbon in the zinc oxide crystalline structure. The higher carbon content resulted in a larger surface area. All composites presented the ability to absorb radiation in less energetic wavelengths, contrary to pure zinc oxide that only absorbs radiation of wavelengths below 420 nm. The optimal dosage and calcination temperature were found to be 0.2 g L−1 and 300 °C. All the developed composites displayed significant photocatalytic activities in the decomposition of methylene blue under both visible and solar light. The composites had superior photocatalytic efficiency under visible light when compared to pure zinc oxide. The XZn 0.5 presented the best degradation efficiency under visible radiation. All materials presented similar photocatalytic responses under solar light, evidencing the synergy between the carbon xerogel and the zinc oxide. The photocatalytic mechanism was evaluated by trapping experiments to be mainly controlled by the electron vacancies that are generated during the photoexcitation of the composites.

Gallotannin mediated silver colloidal nanoparticles as multifunctional nano platform: Rapid colorimetric and turn-on fluorescent sensor for Hg2+, catalytic and In vitro anticancer activities

A simple approach has been developed to prepare gallotannin (GT) mediated silver nanoparticles (AgNPs) for detection of Hg2+ ion in aqueous solution. The synthesized silver nanoparticles was characterized by different techniques such as UV–vis spectrophotometry, XRD, scanning electron microscopy, and EDX. Amongst the all metal ion tested, only Hg2+ shows selective colorimetric and fluorimetric change to GT capped AgNPs. A quick naked eye color change of GT capped AgNPs from yellowish-brown to colorless shows high sensitivity of present method. With addition of Hg2+ ion, the fluorescence enhancement was observed for GT capped AgNPs. The mechanism for the change in color and fluorescence enhancement of nanoparticles with addition of incremental amount of Hg2+ is due to the change in polarization near metal surface region and internal charge transfer phenomenon. The linear range for the detection of Hg2+ was found to be 0.1–1 nM with lower detection limit (LOD) 0.037 nM. The present approach has been successfully utilized to quantitative determination of Hg2+ from environmental samples. The another advantages of prepared silver nanoparticles (GT-AgNPs) is that it shows significant photocatalytic activity for organic transformation and anticancer potential against cancer cell line MDA-MB-231 and A375 with an LD50 of 111.5 µg/mL and 185 µg/mL, respectively.

Mechano-synthesized orange TiO2 shows significant photocatalysis under visible light

Nitrogen and carbon co-doped TiO2 particles with a brilliant yellow-orange color were produced mechanochemically by high-energy ball milling as one-pot synthesis. This facile synthesis required only grinding TiO2 with melamine at room temperature. Using monochoromatic lights with the same intensity in visible and UV, the photocatalytic activity of the TiO2 particles was accurately evaluated with respect to the degradation of an aqueous dye (methylene blue) solution. The activities under visible light (450 and 500 nm) were, respectively, 4 and 2 times higher than that of the unmilled TiO2 under UV light (377 nm), corresponding to 9 and 5 times higher than the UV under the solar light condition. The properties and structure of the co-doped TiO2 particles before and after milling were analyzed using eight experimental methods. As a result, it was found that the nitrogen replaced as an oxygen site in milled TiO2 has the highest concertation (2.3%) in the past studies and the structure of milled TiO2 is composed of a polymorphism of four different solid phases of TiO2, gives significant higher photocatalytic activity at visible light than that of UV light. A good repeatability of the photocatalyst was investigated by the number of cycles for the decomposition reaction of the aquesous dye solution.

Acidic surface niobium pentoxide is catalytic active for CO2 photoreduction

In this paper, we report for the first time the significant photocatalytic activity of Nb-based materials for CO2 reduction. Nb2O5 catalysts were prepared through a modified peroxide sol-gel method using different annealing temperatures, showing activity for CO2 photoreduction in all conditions. The activity and selectivity of the Nb2O5 samples were directly related to their surface acidity: high surface acidity prompted conversion of CO2 to CO, HCOOH, and CH3COOH; low surface acidity prompted conversion of CO2 to CH4. The results also indicated that CO is the main intermediate species of the CO2 photoreduction in all conditions. We have uncovered the role played by the surface acidity of Nb2O5 and the mechanism behind its performance for CO2 photoreduction.

Hierarchical Porous Batio3 Nano-Hexagons as A Visible Light Photocatalyst

Hierarchical porous BaTiO3 nano-hexagons was synthesized via a simple hydrothermal route by using TiO2 and Ba(OH)2.8H2O as starting materials under alkaline environment and its photocatalytic activity was evaluated under visible light by taking methylene blue (MB) as a model pollutant. The prepared BaTiO3 was characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-rays analysis (EDX), high resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) analysis and diffused reflectance spectroscopy (DRS) techniques. It is noteworthy that the BaTiO3 nano-hexagons exhibited significant photocatalytic activity towards the degradation of MB under visible light irradiation. This significant photocatalytic activity of BaTiO3 under visible light is mainly attributed to the special morphology and formation of Ti3+ defects.

A new two-dimensional CoII coordination polymer based on bis[4-(2-methyl-1H-imidazol-1-yl)phenyl] ether and biphenyl-4,4'-diyldicarboxylic acid: synthesis, crystal structure and photocatalytic degradation activity.

A novel two-dimensional CoII coordination framework, namely poly[(μ2-biphenyl-4,4'-diyldicarboxylato-κ2O4:O4'){μ2-bis[4-(2-methyl-1H-imidazol-1-yl)phenyl] ether-κ2N3:N3'}cobalt(II)], [Co(C14H8O4)(C20H18N4O)]n, has been prepared and characterized by IR, elemental analysis, thermal analysis and single-crystal X-ray diffraction. The crystal structure reveals that the compound has an achiral two-dimensional layered structure based on opposite-handed helical chains. In addition, it exhibits significant photocatalytic degradation activity for the degradation of methylene blue.

Fabrication of Graphene–CuO Nanocomposite with Improved Photocatalytic Degradation for Palladium Solution under Solar Light Irradiation

A facile synthesis of graphene oxide-copper oxide nanocomposite (GO-CuO) was performed by using wet chemical method of graphene oxide and copper acetate precursors. The nanocomposite was characterized and intercalated with Raman spectroscopy, FE-SEM, TEM, SAED and EDAX. The crystalline nature was studied from P-XRD. Photocatalytic degradation of palladium ion was studied by using UV-VIS spectrophotometer. Significant high-performance photocatalytic activity of GO-CuO nanocomposite was exhibited on palladium ions degradation under solar light.

Rapid Synthesis via Green Route of Plasmonic Protein-Coated Silver/Silver Chloride Nanoparticles with Controlled Contents of Metallic Silver and Application for Dye Remediation

The use of proteins for surface modifications of hybrid silver nanoparticles (NPs) is still poorly explored. In this study, we report a rapid green route synthesis of plasmonic protein-coated silver/silver chloride NPs (Ag/AgCl NPs) with controlled contents of metallic Ag (Ag0) using a modified photo-irradiation method. The contents of Ag0 were easily controlled varying the proportion between Ag+ and Cl− in the syntheses reactions. Interestingly, the Ag0 content in the protein-coated Ag/AgCl NPs increased with increasing of Cl− concentration. The synthesized plasmonic protein-coated Ag/AgCl NPs exhibited significant photocatalytic activity in the reduction of methylene blue dye under light irradiation due to the synergy between the metallic plasmonic effect and the semiconducting AgCl. However, a significant decrease in the content of semiconducting AgCl resulted in an undesirable synergistic effect. In our green route syntheses, all the properties of Ag/AgCl NPs were maintained with the addition of the advantages of the protein layer, which facilitates the dye adsorption and could contribute, along with Ag0, to reduce the electron–hole pairs recombination rate. Thus, with a simple and fast synthesis strategy these organic–inorganic hybrid NPs have the potential for applications for environmental remediation.