Direct Sunlight Irradiation Research Articles

Construction of p–n junction type Ag2O/SnO2 heterostructure photocatalyst for enhanced organic dye degradation under direct sunlight irradiation: Experimental and theoretical investigations

Construction of p–n junction type Ag2O/SnO2 heterostructure photocatalyst for enhanced organic dye degradation under direct sunlight irradiation: Experimental and theoretical investigations

Experimental and ab initio studies of Co-doped ZnO nanophotocatalyst thin films for dye mineralization.

Pristine ZnO and Co-doped ZnO photocatalyst thin films were fabricated on a ceramic substrate by spray pyrolysis. The optical, morphological and structural properties of the fabricated nanophotocatalyst thin films were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Operational parameters, including dye concentration, oxidant concentration, irradiation time and pH for dye degradation, were optimized by response surface methodology (RSM). The maximum degradation obtained was 93% under ideal conditions, such as pH 7, 3 h of direct sunlight irradiation, 30 mM concentration of oxidant and 10 ppm concentration of dye (MB). The evaluation of the extent of degradation was done using the UV/visible spectrophotometry technique. The reusability of the fabricated thin film was examined under optimized conditions. Density functional theory (DFT) with the B3LYP/LanL2DZ method was used for the theoretical modelling of the fabricated nanomaterials. The optimized structure, theoretical band gaps, IR spectra and Raman spectra of the fabricated pristine ZnO and Co:ZnO nanophotocatalysts were determined.

Role of carbon quantum dots in a strategic approach to prepare pristine Zn2SnO4 and enhance photocatalytic activity under direct sunlight

In the present work, carbon quantum dots (CQDs) are used in a strategic approach to obtain pristine mesoporous Zn 2 SnO 4 (ZTO) and enhanced photodegradation of methylene blue (MB) dye. The Zn 2 SnO 4 /carbon quantum dots (ZTO/C) was hydrothermally prepared using mineralizer, Na 2 CO 3 and quantified amount of sugarcane juice. The mesoporous nature and high surface area of ZTO and ZTO/C was revealed from Brunauer, Emmett and Teller (BET). The close overlapping of CQD with ZTO was evident from the HRTEM and Raman spectra. The MB dye degradation study employing ZTO and ZTO/C catalyst under direct sunlight irradiation showed 84 % and 95 % degradation in 150 min respectively. The presence of CQDs in ZTO/C nanocomposites enhanced the transportation of photoinduced electrons at the interface between ZTO and CQDs, whereas holes stayed in the valence band of ZTO, suppressing the recombination of photogenerated charge carriers during photocatalysis. This study reveals that ZTO/C as a possible candidate for sunlight-driven photocatalysis and environmental remediation. • Synthesis of pristine mesoporous Zn 2 SnO 4 (ZTO) and Zn 2 SnO 4 /carbon quantum dots (ZTO/C) in a strategic method using CQDs • Green synthesis of Carbon quantum dots using sugar cane juice. • High photocatalytic degradation efficiency of 95 % using (ZTO/C) nanocomposite towards methylene blue (MB) dye.

Origanum vulgare manganese ferrite nanocomposite: An advanced multifunctional hybrid material for dye remediation

The purpose of the study was to fabricate sustainable and cost-effective material for the thorough cleansing of polluted water. In this context, an economical, phytogenic and multifunctional Origanum vulgare plant-based nanocomposite material, MnFe2O4/OV, was prepared via one-pot synthetic technique. The synthesized nanocomposite with a band gap of 2.02 eV behaved as an efficient nano-photocatalyst for the degradation of both cationic (crystal violet) and anionic (congo red) dyes under direct sunlight irradiation. The material also inhibited the growth of E. coli and S. aureus bacteria and simultaneously adsorbed both cationic and anionic dyes from water through adsorption. A variety of techniques have been used to characterize the nanocomposite, including X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). Additionally, the kinetics of photodegradation of the aforementioned organic dyes has also been investigated. The MnFe2O4/OV exhibited excellent photocatalytic performance, leading to 43% and 72% degradation within 3 h at rate constants of 2.0 × 10−3 min−1 and 6.0 × 10−3 min−1 for crystal violet and congo red, respectively. The crystal violet and congo red were used to testify to the composite's potential for adsorption under the influence of several process variables, including initial solution pH, contact time, temperature, initial dye concentration, and amount of MnFe2O4/OV. The Langmuir maximum adsorption capacity Qmax as in the range 14.06–14.59 mgg−1 for crystal violet and 34.45–23.93 mgg−1 for congo red at pH 7 within 90 min contact time in the temperature range of 30–50 °C. The phenomenon of adsorption was found feasible and endothermic at all the investigated temperatures. Also, E. coli and S. Aureus bacteria have shown growth suppression activity when exposed to MnFe2O4/OV.As a result, the synthesized nanocomposite, MnFe2O4/OV, proved to be an antimicrobial, multifunctional novel nanocomposite, which is in high demand, and could serve as an affordable, and sustainable material for comprehensive water filtration.

Calcium-based composites directly irradiated by solar spectrum for thermochemical energy storage

The optical absorptance of calcium-based composites used in direct solar-driven calcium-looping thermochemical energy storage systems should be improved. Experimental data obtained by thermogravimetric analyzer (TGA) cannot adequately describe the realistic performance of such calcium-based composites. In this work, calcium-based composites filled in a fixed bed reactor were directly irradiated by concentrated sunlight to examine the performance of thermochemical energy storage under different light illumination conditions. The effects of doping content and concentration ratio of sunlight on the cycling performance of the modified calcium-based composites were investigated under direct solar-driven conditions. The Cr/Mn co-doped CaCO3-based materials with a molar ratio of Ca: Cr: Mn = 100:4:8 could be efficiently operated under direct sunlight irradiation conditions because of a high optical absorption of 73.22 %, achieving gravimetric energy densities of 1090 and 818 kJ/kg in the 1st and 10th cycles, respectively. The cycling performance of the calcium-based composites under different light illumination conditions was compared with that using the TGA device. By comparing the optimal performance in two operating modes, the cycling stability of the calcium-based composites attenuated faster in the solar-driven fixed bed reactor than in the TGA device, which was ascribed to the uneven temperature distribution in the solar-driven reactor. By preventing surface overheating or localized hot spots in a direct solar-driven reactor, cycling stability of the calcium-based composites can be enhanced. Based on this principle, we propose some improvement methods for ensuring uniform temperature distribution in CaCO3-based composites during the direct solar-driven calcination process.

Light-enhanced thermochemical production of solar fuels from methane via nickel-based redox cycle

Thermochemical methane reforming driven by solar energy is one of the efficient ways to store the renewable energy and to simultaneously reduce greenhouse gas emission. We report reaction reactivity of steam reforming of methane using nickel-based oxygen carrier driven by pure thermal heating and direct light irradiation in the same reactor. We find that the light-driven steam methane reforming system show improved conversion and reaction rate compared to that driven by pure thermal heating. We observed that illuminated NiO/NiAl2O4 achieved the same methane conversion rates and the H2 production rate comparable to those obtained on the same samples operated with only a thermal energy input, but at temperatures up to ∼ 50 K lower. Based on in situ diffuse reflectance Infrared Fourier transform spectroscopy (DRIFTs) experiments, we postulate that light on the nickel oxide surface act to activate CH4 desorption and facilitate CHxO species evolution. By the combined effects of selection of chemical looping reactions and operation conditions, the solar-to-fuel efficiency of 16% was achieved. The results showcase the design of more energy-efficient chemical processes with a significant fraction of energy input provided in the form of direct sunlight irradiation as a potent pathway that can complement extremely high-temperature thermochemistry efforts in the quest for more efficient solar fuel production.

Photodegradation of POPs-containing wastewater using sunlight driven Ce-doped-ZnO/g-C3N4 photocatalyst: optimization, and cost-efficiency analysis

In this research, the existence of Ce-ZnO and g-C3N4 was confirmed by XRD, FTIR, SEM, and TEM tests, and EDAX analysis approved the synthesized nanocomposite components as well. Also, BET analysis specified the g-C3N4/Ce-ZnO surface area = 181.08 m2/g and pore size = 35.858 nm, and the bandgap = 2.59 eV was determined by DRS test. The central composite design method optimized the components of nanoparticles, Zinc Nitrate = 280.2 mg, Cerium Nitrate = 17.5 mg, and g-C3N4 = 232.4 mg. The wastewater COD decreased 88 %, and 52 % under sunlight simulated irradiation and direct sunlight irradiation, respectively, by g-C3N4/Ce-ZnO at optimum conditions.

Synthesis and properties of ultra-small BiFeO3 nanoparticles doped with cobalt

Bismuth ferrite (BiFeO3, BFO) is the most promising material in the field of multiferroics. Additionally, it has excellent potential in photocatalysis applications due to its relatively small bandgap, stable structure, and low cost. Doping this material and enhancing its particle size showed promising results in many applications, especially photocatalysis, but the effect of both parameters has never been combined and studied before.In the present work, we report on the effect of cobalt doping of bismuth ferrite Bi Fe1-xCoxO3 x (with x = 0, 0.02, 0.04, 0.06 and 0.08) synthesized by hydrothermal route. The crystalline phase was obtained at a temperature as low as 200 °C. Rietveld's refinement of X-ray diffraction (XRD) confirmed the rhombohedral structure of the crystalline powders. Transmission Electron Microscopy (TEM) alongside High-Resolution Transmission Electron Microscopy (HRTEM) was conducted to probe microstructural features and showed a remarkable decrease in particle size from 12.5 nm to only 4.5 nm, when increasing the cobalt concentration to 8%. The material's optical properties were also studied and showed an increase in band gap values from 2.12 to 2.33eV.The application of the samples to the photodecomposition of methylene blue (MB) under direct sunlight irradiation was reported and have shown unusual results that were explained by the unique sizes of the samples and the phenomena that can occur at that order of magnitude.

Fabrication of charcoal-nickel (II)-poly(acrylic acid) nanocomposite hydrogels for photodegradation of rhodamine B under direct sunlight irradiation

The fabricated hydrogels charcoal-nickel-poly(acrylic acid) (char-Ni-PAA) synthesized by a free-radical polymerization technique was used for rhodamine B dye degradation under direct sunlight irradiation. Different Ni ions compositions were characterized using ATR-FTIR, TGA, EDAX, and SEM techniques. The shift and intensity change of the peaks in the ATR-FTIR spectrum indicated the binding of Ni ions and charcoal onto PAA chains in the hydrogel. EDAX also showed the incorporation of Ni ions into the composites. TGA results revealed the higher thermal stability of the nanocomposite hydrogel. SEM images revealed porous network nanostructures in the composite hydrogels. Ni ions adhered with charcoal provide an environment with high electron mobility to degrade targeted dye molecules under sunlight irradiation. In addition, different surface functional groups of charcoal enhanced the dye adsorption capacity of the composite hydrogel. Charcoal-nickel-poly(acrylic acid) hydrogel containing 1 g Ni ions showed a maximum of 75.56% rhodamine B degradation under direct sunlight irradiation for 8 h in an open atmosphere at a neutral pH solution. The photocatalytic capability of dispersed Ni ions and enhanced dye adsorption capacity of charcoal improved the photodegradation activity of the fabricated char-Ni-PAA nanocomposite hydrogels. The synthesized hydrogels containing a higher amount of Ni ions also showed promising antibacterial activity towards two microorganisms, B. cereus, and P. aeruginosa, as gram-positive and gram-negative bacteria under visible light illumination. The higher photodegradation activity and antibacterial properties of the synthesized char-Ni-PAA nanocomposite hydrogels demonstrate their efficacy in the treatment of textile wastewater under direct sunlight irradiation.

Pilot-scale NO removal efficacy of photocatalytic roofing granules under urban environmental conditions

Photocatalytic building envelope materials harness sunlight to activate self-cleaning and de-polluting properties, which can help mitigate the urban heat island effect and abate urban pollution. The performance of roofing membranes manufactured with bright-white photocatalytic (BWP) granules, and with a non-photocatalytic bright-white control (BWC), were evaluated. The solar reflectance of unexposed specimens was 0.56 for BWP and 0.60 for BWC. Small changes in solar reflectance with respect to the initial values were observed during 22 months of field exposure between March 2020 and January 2022, indicating good resistance to soiling. Changes in the de-pollution capacity during the same period were quantified with a bench-scale method adapted from the ISO Standard 22197-1, in which unexposed and aged specimens were placed horizontally inside a flow chamber admitting clean air enriched with nitric oxide (NO) under UV irradiation. In addition, a pilot-scale approach was developed to evaluate the photocatalytic performance of the same materials under more realistic urban environmental conditions. An outdoor exposure chamber was designed and built with a rectangular stainless-steel main body topped with a UV-transparent fluorinated ethylene propylene (FEP) thin film. The area of the 30 cm × 90 cm BWP specimen tested in the outdoor chamber was more than one order of magnitude larger than those evaluated in the benchtop apparatus. The BWP membrane was pre-activated by field exposure for 75 days. The pilot-scale chamber operation was validated in the laboratory using UV lamps to irradiate the BWP membrane and a reference TiO 2 -coated aluminum plate (P25, 1 g m −2 ) of the same dimensions. Tests showed comparable or better performance of the BWP membrane with respect to the P25 film. Its de-pollution capacity was tested with direct sunlight irradiation in Berkeley, California (37.88° N, 122.25° W) during June 2020. Urban air was enriched with NO, or with a NO/NO 2 mixture, and circulated through the pilot-scale chamber at two different flows: 1.1 and 440 L min −1 . The gas phase concentrations of NO and NO 2 were measured upstream and downstream of the tested specimen with a chemiluminescence analyzer. Upstream levels of the challenge gases were high but realistic, not exceeding 200 ppb. The UV irradiance outdoors (15–30 W m −2 ) was higher and more variable than in indoor tests (11.5 W m −2 ), leading to overall higher NO deposition velocity under direct sunlight. In outdoor measurements, the NO deposition velocity increased at higher irradiances. When NO was the only challenge gas, a fraction of NO was oxidized to NO 2 resulting in lower NO and higher NO 2 downstream concentrations. However, when tested with NO/NO 2 mixtures, the concentration of both compounds decreased during irradiation, and the surface showed a faster loss of photoactivity for NO 2 , compared with NO. These effects are consistent with those observed in the laboratory. The NO x deposition velocity outdoors was 0.7 and 105 μmol h −1 m −2 for the low and high air flow, respectively. • The de-NO x performance of a photocatalytic roofing membrane was evaluated. • ISO Standard 22197-1 was used to determine NO x removal rates in bench tests. • Tested specimens were aged in the field over a 22-month period. • A flow exposure chamber was built for outdoor pilot-scale tests. • The NO deposition velocity increased with UV irradiance between 15 and 30 W m −2

Synthesis and characterization of silver-indium and antimony selenide: role in photocatalytic degradation of dyes

These days, water contamination poses a severe threat to the ecosystem and demands immediate care. This study examined the need to reduce water pollution using clean, renewable energy (solar light irradiations) for the degradation of Congo red by Silver-indium and antimony selenide with chemical composition AgInSbSe3. The sample was fabricated through a hydrothermal technique. The synthesized sample was characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Ultraviolet-Visible spectroscopy. The X-ray diffraction confirms crystalline structure of the synthesized sample. The SEM analysis reveals irregular grains and exhibits a very small inter-particle distance. SEM provides the morphology of the synthesized sample, the grain size of the synthesized sample was 0.58 μm. FTIR results revealed specific absorption bands in the range of 400–4000 cm−1; optical properties are studied through UV-Vis-spectroscopy. The synthesized sample has 1.97 eV bandgap which is suitable for degradation of organic pollutants. The photocatalytic activity of the material is checked by degrading the Congo red dye under direct sunlight irradiation and for the 75 min illumination 77.8% degradation efficiency is attained.

Development of immobilised sunlight active W-Mo/Mo-V/V-W co-doped TiO2 photocatalyst by plasma electrolytic oxidation

W-Mo/Mo-V/V-W co-doped TiO2 photocatalyst for the effective degradation of MB (methylene blue) dye under sunlight irradiation was successfully prepared by one-step Plasma Electrolytic Oxidation (PEO) process. The XRD, XPS, and EDS results revealed that W/Mo/V were co-doped in the TiO2 lattice. The highest redshift in the light absorption edge is recorded for the sample MV (Mo-V co-doped TiO2) with a bandgap of 2.51 eV, whereas the bandgaps for WM (W-Mo co-doped TiO2) and VW (V-W co-doped TiO2) are recorded as 2.96 eV and 2.58 eV, respectively. The co-doped photocatalysts show a typical PEO structure with a high degree of porosity favouring the dye adsorption ability. EIS, LSV, and PL analysis confirmed that the co-doped coatings pose a high degree of charge separation, suppressed charge carriers' recombination, and increased the ability to produce photocurrent. Under direct sunlight irradiation, the sample MV showed the highest photocatalytic efficiency, confirmed by MB dye degradation, then the other co-doped and undoped TiO2. This can be attributed to the synergetic effects of intense visible light absorption in the solar spectrum and the reduced charge carriers' recombination rate by acting as the trapping sites for photogenerated electrons and holes. Finally, this immobilised co-doped photocatalyst developed by the PEO process is a promising system in the quest to establish a renewable energy-assisted strategy for textile wastewater treatment application. • Developed direct sunlight active W-Mo/Mo-V/V-W co-doped TiO 2 on Cp-Ti by PEO. • Mo-V co-doped TiO 2 (Eg of 2.41 eV) shows the highest redshift in light absorption. • Immobilised Mo-V co-doped TiO 2 shows the highest dye degradation and mineralisation. • Low Eg and e + /h − recombination rate is due to the synergetic effect of V and Mo.

Sunlight-driven photocatalytic degradation of 4-nitrophenol and adsorptive removal of Mn (II) ions from industrial wastewater by biogenic synthesized CuO/SnO2 heterojunction

Toxic substances like organic pollutants and heavy metal ions require urgent removal from contaminated water for protection of human health. The presence of these pollutants in water beyond the permissible limits has negative consequences for human health, the climate, and the environment. Experts have paid close attention to eliminate these hazardous substances from natural water by using heterojunctions over the last decade. From this perspective, CuO/SnO2 heterojunction has been constructed for the first time by green synthesis route using fruit part of Carica papaya extract. The fabricated heterojunction photocatalyst was characterized using several sophisticated techniques like UV–vis, FTIR, XRD, field-emission scanning electron microscopy, energy-dispersive spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and BET-BJH. Catalytic potential of the CuO/SnO2 heterojunction was descriptively explored for reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under direct sunlight irradiation. Complete conversion of toxic 4-NP into 4-AP was achieved in 20 min with a rate constant of 0.23 min−1, and the intermediates formed were analyzed by LC-MS. Furthermore, the heterojunction was used for removing toxic Mn2+ ions from industrial effluents. The influence of various experimental conditions on adsorption, including pH of the solution, amount of adsorbent, time of contact, and temperature, was carefully examined. The Langmuir, Freundlich, and Temkin isotherm models were used to study the equilibrium adsorption behavior of the heterojunction. The maximum adsorption by the CuO/SnO2 heterojunction was determined to be 227 mg/g. The biogenic synthesized heterojunction successfully removed Mn2+ ions from the real samples of industry effluents. Hence, biogenic CuO/SnO2 heterojunction could be used as a novel material for the reduction of 4-NP and adsorptive removal of Mn2+ ions.

Multi-functional carbon dots from simple precursors: An excellent heavy metal ions sensor with photocatalytic activity in aqueous environment

Carbon dots (CDs) with core and surface structures were prepared from simple precursors (ethylenediamine and ethylene glycol) by using house-hold microwave oven. The structural and optical properties were exclusively studied with HR-TEM, XRD, UV-Vis and PL techniques. The fluorescence emission of the CDs was predominantly dependent and/or independent on excitation-wavelength are owed to the existence of assorted functional groups on surface and uniform arrangement in core structure. Hence, the CDs shows better stability against photo bleaching and ionic strength. In addition, CDs are successfully used to detect heavy metal ions such as Cr6+ and Hg2+ selectively by fluorescence-based detection method through different quenching mechanisms with lower detection limit of 0.09 µM for Cr6+ and 0.16 µM for Hg2+. Similarly, we attempted rapid, simple and low cost on-field application by using two different cellulose-based filter papers for visual detection of Cr6+ and Hg2+ metal ions for quick and cheap method. Moreover, CDs were successfully employed for detoxification/degradation of Rhodamine B (RhB) dye and also 87 % degradation were achieved over the time period of 140 min under direct sunlight irradiation. At finally, the innovative CDs are superior multi-behavior material for the several environmental applications.

Photocatalytic degradation of methylene blue dye under direct sunlight irradiation using SnO2 nanoparticles

• SnO 2 has been successfully synthesized using hydrothermal method. • Methylene blue was efficiently degraded by SnO 2 NPs under sunlight irradiation. • Catalyst dose and dye initial concentration significantly affected the rate of MB decomposition. • The rate of MB degradation was enhanced in the presence of H 2 O 2 oxidant. In this work, we report the hydrothermal synthesis, characterization, and photocatalytic activity of SnO 2 nanoparticles (NPs) towards methylene blue (MB) dye. The synthesized sample was characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet–visible (UV–Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N 2 -sorption isotherm techniques. Results show that synthesized sample was tetragonal structure with an optical bandgap, average crystallite size, and degree of crystallinity equal to 3.67 eV, 21 nm, and 70%, respectively. The impacts of dye initial concentration, catalyst dose, and oxidant addition on the sunlight-assisted photodegradation performance were investigated. Degradation of 97% was achieved in 2 h of irradiation utilizing 10 ppm dye initial concentration and 40 mg catalyst dose at natural pH and in the absence of any oxidant. However, in the presence of the H 2 O 2 oxidant complete removal was observed in just 90 min without changing other parameters.

Degradation of pollutants in solid and gas states using waterborne acrylic nanocomposite paints

In this study, TiO2/SiO2 nanoparticles were synthesized using titanium tetraisopropoxide and tetraethoxysilane in a two-step sol-gel route. FTIR, XRD, UV–Vis, and XPS techniques were used to characterize the synthesized nanoparticles. Fe-SEM was utilized to evaluate the particle size of the synthesized nanoparticles (30.35 ± 4.52 nm). Photo-degradation of rhodamine B (Rh.B) as a solid pollutant model and NO2 as a typical gaseous pollutant was assessed on the surface of the waterborne-acrylic coatings containing TiO2/SiO2 nanoparticles (TSC.La) under direct sunlight irradiation and accelerated weathering conditions and the results were compared with a P25–TiO2 nanoparticle (UT.La) embedded coating samples.To evaluate the degradation of Rh.B, color coordinates (L*a*b*) were measured, while the degradation of NO2 was determined in a batch-designed photocatalytic reactor by measuring the reduction in gas concentration. For the TSC.La-sample exposed to accelerated weathering conditions, the changes in a* parameter (Δa*) were about 60%, which was 44 times greater than the changes in this parameter for the sample exposed to sunlight. The surface morphology of the exposed samples to the accelerated weathering conditions was evaluated using AFM and BET measurements. The AFM results indicated that TiO2/SiO2 nanoparticles lead to less surface degradation of the paints compared to the commercial TiO2 nanoparticles. NO2 concentration decreased steadily in the reactor from 30 to 27 ppm, at an RH%<20 in the presence of UT.La or TSC.La-samples after 45 and 60 min of UV exposure. This reduction in gas concentration is equivalent to photocatalytic power of 6 and 8 mLm−2h−1, for the two samples, respectively.

Enhanced sunlight-driven photocatalytic, supercapacitor and antibacterial applications based on graphene oxide and magnetite-graphene oxide nanocomposites

Herein, we report an enhanced sunlight-driven photocatalytic, supercapacitor and antibacterial applications based on graphene oxide (GO) and magnetite -graphene oxide (Fe3O4-GO) nanocomposites. The materials were synthesized by the facile chemical precipitation method and examined in detail by various techniques including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–Visible (UV–Vis.) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometer (VSM). The effective production of GO and Fe3O4-GO nanocomposite was validated by XRD, while UV–Vis. measurements demonstrated a smaller bandgap for the nanocomposites. The uniform distribution of Fe3O4 nanoparticles over GO nanosheets were observed through FESEM and TEM studies. The prepared materials were further utilized as sun-light driven photocatalyst for the degradation of methylene blue (MB) dye, working electrode for the supercapacitor application and efficient biomaterial to examine the antibacterial characteristics against Gram-positive (S. aureus) and Gram-negative (E. Coli) bacterial strains. As an efficient photocatalyst, the Fe3O4-GO nanocomposites exhibited a rapid degradation (91% in 30 min) for methylene blue dye under direct sunlight irradiation. The synthesized nanocomposite exhibited a maximum specific capacitance of 775 Fg-1 at a current density of 1 Ag-1 and exceptional chemical stability as an electrode material. Antibacterial activities of the synthesized materials were also exhibited against Gram-positive (S. aureus) and Gram-negative (E. coli) bacterial strains.

Echinops kebericho Aqueous Root Extract Assisted Green Synthesis of Zinc Oxide Nanoparticles for Photocatalytic Degradation of Methylene Blue

Wastewater treatment from industrial effluents is a global problem. Searching for environmentally safe and green technology is in the utmost interest of the scientific community. Especially organic pollutants, due to their difficulty to biodegrade, have posed a problem to human health and the aquatic environment. Hence, we reported plant extract-mediated synthesis of zinc oxide nanoparticles (ZnO NPs) in this study for photocatalytic degradation of methylene blue (MB) under sunlight irradiation. Echinops kebericho root extract was used as a reducing and stabilizing agent during the synthesis of ZnO NPs. The presence of phenolics, tannins, flavonoids, terpenoids, and alkaloids was qualitatively confirmed in the aqueous root extract of the plant under study. These secondary metabolites have a high potential in facilitating capping and stabilizing effects on the formation of ZnO nanostructures. Powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were used to characterize the crystal structure and chemical bond of ZnO NPs, respectively. The XRD patterns showed the formation of pure phase hexagonal wurtzite ZnO NPs with an average crystal size of 14.67 nm. The photocatalytic degradation efficiency of ZnO NPs (80 mg) to remove 10 mg/L of MB dye was found to be 92.2% at pH=10 and 120 min contact time under direct sunlight irradiation. Therefore, ZnO NPs synthesized using E.kebericho were potential photocatalysts for the degradation of MB from wastewater for at least three cycles.

General and Efficient C–P Bond Formation by Quantum Dots and Visible Light

General and Efficient C–P Bond Formation by Quantum Dots and Visible Light

Rare earth (Gd, La) co-doped ZnO nanoflowers for direct sunlight driven photocatalytic activity

In this work Gd/La@ZnO nanoflower photocatalyst was successfully synthesized by a co-precipitation method and applied for rhodamine B (Rh B) and tetracycline (TCN) degradation under direct sunlight irradiation. The doping of rare earth elements extends the optical absorption wavelength of ZnO from UV region (390 nm) to visible-light region (401 nm). In addition, the co-doped ZnO nanoflower exhibits a lower charge recombination efficiency which was confirmed by photoluminescence emission analysis. Moreover, the co-doped ZnO nanoflower exhibits the maximum degradation efficiency of 91% for Rh B and 74% for TCN under sunlight irradiation. The calculated synergistic index of co-doped ZnO is higher than that of the pure ZnO. Reactive radicals' production was confirmed by terephthalic acid (TA) and nitro-blue tetrazolium (NBT) tests. The holes and hydroxyl (•OH) radicals play the major role in degradation reaction and it was confirmed by scavenger's test. Moreover, the recycling test confirms the stability of the photocatalyst.