High Photocatalytic Properties Research Articles

Photocatalytic CO2 reduction with new band gap energy evaluation from spectroscopic relationship of graphene-Mg2CuSnCoO6 composite bridged with organics

A new structure of graphene-Mg 2 CuSnCoO 6 composite bridged with gallic acid (GMG) was synthesized with a novel method. Band gap energy of the newly synthesized nanocomposite was evaluated with a laser-wavelength region and DRS method. Evaluation and analysis were based on the relationship among XRD, HRTEM, XPS, Raman scattering, and computer simulated model structure. Changes in the structure of graphene or graphene-based composite were associated with location changes of the valence band and the conduction band. Electron density was used to confirm the number of electrons by computer simulation. Finally, such graphene-Mg 2 CuSnCoO 6 -gallic acid nanocomposite was used for photocatalytic CO 2 reduction into methanol. Under UV-light irradiation, the highest methanol yield was 5.576% with 0.6 g of scavenger. This work might offer a promising strategy for measuring band gap energies of different types of semiconductors. • Synthesis of new-structured Graphene-Mg 2 CuSnCoO 6 composite bridged with Gallic acid. • The evaluation of new band gap energy value. • Photocatalytic activity for the CO 2 reduction by novel ternary nanocomposite. • The high methanol production rate with scavengers. • High stability and photocatalytic efficient properties for production of solar fuel.

Facile Synthesis of 3D Sea Urchin-like CuO Microspheres Structures and its Higher Photocatalytic Properties

The three-dimensional (3D) sea urchin-like CuO microspheres structures were successfully synthesized by a simple hydrothermal method. With the hydrothermal temperature increases, the morphology of CuO micro-/nanostructures has changed: When the hydrothermal temperature reaches above 40 °C, the irregular CuO particles transform into a 3D sea urchin-like CuO microspheres. X-ray diffraction spectrum and Raman scatting spectra confirm that the obtained 3D sea urchin-like CuO microspheres at hydrothermal temperature of 60 °C are composed of a high purity and single-phase monoclinic CuO. It is found that the 3D sea urchin-like CuO microspheres structures exhibit the better photocatalytic property for degradation of methylene blue (MB) solution under the visible light irradiation compared to the irregular CuO particles, which duo to the relatively larger specific surface area of the sea urchin-like CuO microspheres structures, exposing more active sites and increasing the contact area between the catalyst and dye molecule. This remarkable photocatalytic performance of the 3D sea urchin-like CuO microspheres structures might has a promising application in waste water treatment.

Terminal p-π conjugation induced excited-state symmetry-breaking charge separation for porous carbon nitride based heterojunction

To reach the purpose of high photocatalytic property, efficient charge separation is needed. Own to the low crystalline and two dimensional characters, it is rather harder to obtain the photoinduced charge transferring information for g-C3N4 than faceted crystal materials. Herein, images for distributions of photoinduced electrons and holes were utilized to analyze the excited-state characteristics and charge transfer directions. Both the theoretical calculation and experimental results reveal that the riched terminal NHx p-π conjugation groups for defect porous carbon nitride (PCN) destroy the symmetry of intrinsic g-C3N4 (CN), which results in a spatial asymmetry distribution of photoinduced electrons and holes, and enhanced photocatalytic activity. To further improve PCN activity, a novel ternary Ni2P/Zn0.2Cd0.8S/PCN photocatalyst was constructed and the H2 evolution rate was 3.04 times of PCN. The enhanced H2 generation performance is attributed to NHx groups hydrogen bond induced well-connection in the ternary Ni2P/Zn0.2Cd0.8S/PCN heterojunction photocatalysts.

Enhanced photocatalytic performance of PdO-loaded heterostructured nanobelts to degrade phenol

Heterostructured catalysts play a significant role in the photodegradation of pollutants in wastewater. Combining the large surface of nanobelts with the high photocatalytic property of titanium dioxide (TiO2) nanoparticles is a promising method for preparing photocatalysts, which have an advanced photocatalytic activity and are easy to precipitate. In this work, titanium dioxide nanobelts (NB) and acid corroded titanium dioxide nanobelts (C-NB) were synthesized via a hydrothermal process under alkaline conditions. Their surfaces were then loaded with palladium oxide (PdO) nanoparticles to prepare heterostructured photocatalysts (PdO-NB and PdO-C-NB) by a well-designed chemical precipitation method. The photodegradation efficiencies of the four catalysts for phenol, as well as for methyl orange, were tested and the order of degradation efficiency was found to be PdO-C-NB > PdO-NB > C-NB > NB. A degradation efficiency of 61% for phenol was achieved within 90 min using PdO-C-NB, which was nearly twice as much as using NB. The enhanced photocatalytic property of PdO-C-NB was due to the large specific surface area, abundant photocatalytic active sites and the low recombination rate of electron-hole pairs. Therefore, the degradation of phenol and methyl orange was speeded up considerably. Considering the high catalytic activity of PdO-C-NB, the heterostructure catalyst is of great significance to the degradation of organic wastewater, and has an important impact on our ecological environment and human health.

Application Titanium Dioxide Nanotube from Natural Source as Tooth Whitening

Nanotube material that has been synthesized for decades is Titanium Dioxide Nanotube (TDN) because it has high photocatalytic properties and produces free radicals that can whiten teeth. Tooth whitening materials that are used in the public is such as H2O2 with high concentrations so that they endanger the health of tooth enamel. Therefore, this research uses TDN as a natural teeth whitening agent with low H2O2 concentrations. TDN is obtained from natural materials, mineral sand which is chemically processed using sodium hydroxide in an autoclave for 24 hours. The amount of free radicals is determined by ESR and the effect of teeth whitening determined by immersing the teeth in a 3% TDN and H202 solution and then characterized by the UV-Vis PC 2401 Spectrophotometer. The results showed that TDN produced O2 − free radicals which could degrade tooth color up to turned brighter.

Preparation of Ag–Bi12SiO20/Bi2SiO5 with high visible light photocatalytic property: the synergistic effect of the heterojunction and the heterogeneous interface

The bismuth silicate heterogeneous powders were prepared by Pechini sol–gel method, and Ag–Bi12SiO20/Bi2SiO5 (Ag–BSO) were prepared by photoreduction method. The crystal phase, morphology, crystal structure and optical properties of the samples were systematically characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, FTIR spectrometer and UV–Vis–NIR spectrophotometer. The photocatalytic performance of BSO and Ag–BSO samples with different Ag contents was investigated. The results show that the degradation rate of Rhodamine B in BSO and Ag–BSO system under visible light is about 56% and 90%, respectively. With a suitable concentration of Ag solution, a heterogeneous interface is formed between Ag and BSO, which greatly improves the photocatalytic activity of BSO. Moreover, the synergistic effect of the heterojunction and the heterogeneous interface greatly enhances the photocatalytic performance.

Preparation and application of carbon and hollow TiO2 microspheres by microwave heating at a low temperature

Abstract A fast, simple, and energy-saving microwave-assisted approach was successfully developed to prepare carbon microspheres. The carbon microspheres with a uniform particle size and good dispersity were prepared using glucose as the raw material and HCl as the dehydrating agent at low temperature (90°C) in an open system with the assistance of microwave heating. The carbon microspheres were characterized by elemental analysis, XRD, SEM, FTIR, TG, and Raman. The results showed that the carbon microspheres prepared under the condition of 18.5% (v/v) HCl and heating for 30 min by microwave had a narrow size distribution. The core–shell structure of the carbon core and TiO2 shell was prepared with (NH4)2TiF6, H3BO3 using the microwave-assisted method. The hollow TiO2 microspheres with good crystallinity and high photocatalytic properties were successfully prepared by sacrificing the carbon microspheres.

A new core–shell Z-scheme heterojunction structured La(OH)3@In2S3 composite with superior photocatalytic performance

Constructing Z-scheme heterojunction photocatalyst with strong redox ability to make for enhanced photocatalytic performance and efficient charge separation is extremely attractive but still underdeveloped. Herein, a Z-scheme heterojunction structured La(OH)3@In2S3 composite (labeled by “LIS”) with photocatalytic for the methylene orange (MO) degradation under simulated light irradiation has been developed. The as-prepared LIS, together with commercial La(OH)3 and pure In2S3 fabricated with the identical processing method and starting materials as those of LIS, was characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra and electrochemical impedance spectroscopy. The results show the heterojunction of La(OH)3/In2S3 has prolonged the lifetime of the photo-generated carriers. The photocatalytic activity test shows that over only a small amount (0.02 g in 100 ml MO) of LIS, the photodegradation rate of 95% toward MO can be obtained in 90 min, which is about 3.4 times higher than that over pure In2S3. The active species trapping experiments indicate that there were four active species playing roles in photodegradation as the following order: e– = ∙OH < h+ < ∙O2–. A mechanism of Z-scheme heterojunction was proposed and well explained the enhanced photocatalytic performance. This work provides a new cost-effective photocatalyst with high photocatalytic properties.

Sisal-like Sn2+doped ZnO hierarchical structures: synthesis, growth mechanism, and their application in photocatalysis

Sisal-like Sn doped ZnO hierarchical structures were prepared by the hydrothermal method without employing templates or matrices. The architectures show enhanced light absorption, high photocatalytic properties, good stability and reusability.

Mulberry-like BiVO4 architectures: synthesis, characterization and their application in photocatalysis

Mulberry-like BiVO4 architectures were prepared by a facile solvothermal route. The obtained architectures showed enhanced light absorption, high photocatalytic properties, good stability and reusability.

ZnO nanoparticles decorated multiwall carbon nanotube assisted ZnMgAl layered triple hydroxide hybrid photocatalyst for visible light-driven organic pollutants removal

Multiwall carbon nanotubes (MWCNTs) supported by zinc-oxide nanoparticles with a ZnMgAl layered-triple-hydroxide (LTH) hybrid was synthesised via direct hydrothermal treatment. In the present investigation, the photocatalytic activity of the prepared hybrid materials was investigated using methylene blue and colourless phenol under visible light irradiation. The photocatalytic degradation efficiency of LTH, MWCNT, and MWCNT ZnO LTH is 48.11%, 4.4%, and 96.7% respectively. The prepared hybrid nanostructure shows a high photocatalytic property due to its synergetic effect, high charge carrier separation, and enhanced visible light absorption surface. The results indicated that the introduction of MWCNTs into the prepared catalyst can increase the photocatalytic activity because the oxidised MWCNTs act as a charge/electron transfer medium in the composite material. The trapping study was performed to examine the role of the active species in the photodegradation process. The abundance of more hydroxyl groups on the surface of the MWCNTs and in the LTH may efficiently improve the photocatalytic activity. The use of MWCNTs improved the catalytic activity of the prepared photocatalyst. The prepared hybrid material especially enhances the visible light absorption and, thus, the photocatalytic activity and cycle stability of the catalyst material.

Exploring The Effect of Precursors of Polymeric Carbon Nitride Nanosheets on their Photo and Electrocatalytic Applications

AbstractIn the present study, we have performed a case study to understand the ability of bulk polymeric carbon nitride (P‐CN) derived from various precursors such as urea, melamine, and dicyandiamide namely UCN, MCN and, DCN respectively via thermal condensation process and also their corresponding thermally exfoliated nanosheets such as TE_UCN, TE_MCN, and TE_DCN. Compared with the bulk P‐CN, all the thermally exfoliated samples retained higher surface area and shows superior photogenerated charge carrier transfer and separation. Among the thermally exfoliated P‐CN nanosheets, TE_UCN gives highly porous nanosheets with a specific surface area of 179 m2/g, and large band gap (3.01 eV). Despite its poor electronic band structure, the large surface area of TE_UCN has contributed more to the excellent photogenerated charge carrier separation, which resulted in their highest photocatalytic property against the degradation of an organic dye rhodamine B(RhB) under natural sunlight. The electrochemical experiments on all the three samples of nanosheets of P‐CN revealed that TE_UCN is the best electrode material for supercapacitors. TE_UCN displays excellent capacitance properties in 0.5 M H2SO4 electrolyte with a specific capacitance of 128.7 Fg−1. Finally, the electrocatalytic activity investigation of the samples of P‐CN nanosheets revealed that TE_DCN has more catalytic activity towards HER. This study demonstrates that texture, electrochemical capacitance, electro and photcatalytic properties of nanosheets of P‐CN can be improved by the judicial choice of the precursor molecules.

B/Co/Fe tridoped TiO2/SiO2 composite films for improved photocatalytic degradation of organic pollutants under visible light

In order to effectively overcome the inherent defects of TiO2 in practical applications including low quantum efficiency and wide band gap, the B/Co/Fe tridoped TiO2/SiO2 composite films with high photocatalytic properties were prepared by the sol-gel method. The physicochemical properties of catalysts were characterized by XRD, FE-SEM, EDS, DTA-TG, BET, DRS and PL. The results shown that the compositing of SiO2 and doping of B/Co/Fe ions in TiO2 could effectively inhibit the phase transformation of anatase to rutile and the growing of crystal grains at high annealing temperatures. The compositing of SiO2 could enhance the specific surface area (82.6 increased to 335.8 m2/g) of samples and provide more adsorption sites. The doping of B/Co/Fe tridoping could form impurity levels in the band gap of TiO2 to shorten the band gap energy (2.54 ev). And the B/Co/Fe tridoped TiO2/SiO2 films could increase the interfacial transfer rate and decrease recombination rate of electrons and holes. The photocatalytic activities of the B/Co/Fe tridoped TiO2/SiO2 films were evaluated under UV or visible light irradiation with two pollutants as target for photodegradation. The results indicated that the films exhibited more excellent photocatalytic activities compared to pure TiO2. The plausible photocatalytic degradation mechanism had been proposed.

Urea and green tea like precursors for the preparation of g-C3N4 based carbon nanomaterials (CNMs) composites as photocatalysts for photodegradation of pollutants under UV light irradiation

To overcome the drawbacks of pure g-C3N4 in photocatalysis, namely insufficient light absorption and fast recombination of its photogenerated charges, g-C3N4-based nanocomposites were investigated. In detail, this study focuses on a novel route by which carbon nanomaterials (CNMs) might be inserted into the structure of g-C3N4 to form hybrid materials that possess great surface area with high photocatalytic and adsorption properties. The g-C3N4/CNMs composites with high photo-activity were obtained via a one-pot synthesis using urea and green tea leaves as cheap and renewable materials. After exfoliation, porous nanosheets with a surface area of about 128 m2 g−1, providing more active sites for both adsorption and efficient photocatalytic degradation of methylene blue, were obtained. The green tea leaves seem to act as a templating agent that control the morphology, growth, and final structure of the composite. From the first-order kinetic model, the reaction rate constant for the nanosheets g-C3N4/CNMs was determined to be kapp =4.7 min−1, which was approximately more than twice that of pure nanosheets g-C3N4 (kapp = 2.0 min−1). Besides, the g-C3N4/CNMs nanocomposite shows an accurate reusability and stability as compared to g-C3N4.

Controllable Synthesis of Flower-Like MoS₂ and Its Quick Photodegradation of Methylene Blue Under Visible Irradiation.

Molybdenum disulfide (MoS₂) was synthesized via hydrothermal process under the assistance of citric acid, which exhibited high photocatalytic property in the application of methylene blue (MB) degradation. The flower ball microstructure of MoS₂ changed with different amounts of citric acid. X-ray diffraction (XRD), Scanning electron microscope (SEM), UV-Vis diffuse reflectance spectra have been employed to characterize the samples. It improved the photocatalytic efficiency nearly 19.77% compared to MoS₂ without citric acid. When H₂O₂ was added, the synergistic effect of MoS₂ and hydrogen peroxide (H₂O₂) was observed in photocatalytic reaction system, which degraded MB completely within 40 min under visible light irradiation.

Photocatalytic Degradation of Malachite Green Dye by Plant-mediated Biosynthesized Zinc Oxide Nanoparticles

Photocatalytic activity of ZnO-NPs was tested by degradation of Malachite Green dye under UV light irradiation. The ZnO-NPs were biosynthesized using Punica granatum (pomegranate) fruit peels extract as the stabilizing agent. Simple sol-gel method and calcination in different temperatures (400, 500, 600 and 700°C) were carried out to obtain pure ZnO-NPs with high photocatalytic properties. In the degradation studies, 20 mg ZnO-NPs were used to degrade Malachite Green dye of 10 ppm initial concentration for a total period of 50 minutes in a 100 ml reaction volume. Results obtained shown that ZnO-NPs calcined in 700°C had the highest removal efficiency at about 99% in 40 minutes. This proves that biosynthesized ZnO-NPs have a high potential to be used as a photocatalyst to degrade textile dyes in a short time for wastewater treatments.

Granulated Graphene Oxide/Titanium Dioxide Composite Aerogel as a High-Performance Photocatalyst

A composite photocatalyst based on graphene oxide and titanium dioxide has been developed and tested. The catalyst has been obtained as an aerogel, which consisted of granules (spheres and hemispheres) with a diameter of 4–6 mm. This form of catalyst has been proved more convenient for use in comparison with powder photocatalysts from a technological point of view. The resulting composites have shown high photocatalytic properties exemplified by photodegradation of the basic dyes methyl violet and methylene blue in aqueous solutions.

Hybrid adsorption–photocatalysis properties of quaternary magneto-plasmonic ZnO/MWCNTs nanocomposite for applying synergistic photocatalytic removal and membrane filtration in industrial wastewater treatment

A new multifunctional filtration membrane was prepared by twofold advantages of conventional polymeric-membrane as the supporting layer and magneto-plasmonic Ag-doped ZnO@Fe3O4/MWCNTs nanocomposite as the functional layer. Poly acrylic acid (PAA)-modified polyamide (PA) discs (PAA-PA) were applied to increase the hydrophilicity of prepared membrane and X-Ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used for characterization. The grafting yield of PAA in the pores and on the surface of PA was 17 wt.% and weigh difference between PAA-PA membrane before and after modifying with the photocatalyst was 8.7 mg. The amount of photocatalyst loading in the prepared membrane was obtained 6.49 g m−2. The synergistic effect of photocatalysis and membrane filtration was evaluated by investigating removal efficiency of amoxicillin (AMOX) as model pollutant using photocatalytic filtration concentration (CPF) parameter under a solar-simulated xenon lamp and the prepared photocatalyst-grafted PAA-PA membrane (PC-PAA-PA) was exhibited better removal ability than bare PA. The flux performance and antifouling property of the prepared membrane was investigated using pharmaceutical wastewater samples and the results revealed that the PC-PAA-PA exhibited good multifunctional characteristics such as high photocatalytic property, flux stability, and antifouling potential. The fouling process was performed in triplicate and the results demonstrated good stability of the photocatalyst on the membrane surface during operation. It can be concluded that by using a simple process for grafting of the photocatalyst to the membrane and the excellent antifouling ability of the resulting filter, an efficient reactor with antifouling characteristics can be constructed to produce cleaner water.

Preparation of Hollow Flower-Like Microspherical β-Bi2O3/BiOCl Heterojunction and High Photocatalytic Property for Tetracycline Hydrochloride Degradation.

Tetracycline cannot be effectively degraded in wastewater treatment. Therefore, the development of excellent photocatalysts is of significant importance for environmental protection. In this study, a β-Bi2O3/BiOCl heterojunction photocatalyst with hollow flower-like microspheres was successfully synthesized by the in-situ reaction of HCl and β-Bi2O3 hollow spheres. The prepared samples are characterized by Scanning electron microscopy, Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 physical adsorption, UV-vis diffuse reflectance spectroscopy, and Photoluminescence. Then, research on the photocatalytic performance for the degradation of tetracycline hydrochloride was conducted. The results show that the photocatalytic performance of the β-Bi2O3/BiOCl composite is significantly better than the β-Bi2O3 and BiOCl. The increase in photocatalytic activity is due to the formation of a heterojunction between β-Bi2O3 and BiOCl, which effectively promotes the separation of photogenerated electron-hole pairs. Additionally, the heterojunction nanocomposite demonstrated the outstanding photocatalytic stability after five cycles, which indicates that the material can be used for water environment purification. This paper provides assistance for studying the photocatalytic mechanism of heterojunction photocatalytic materials.

Controlled synthesis and high photocatalytic properties of stannic oxide nanoflowers

Controlled synthesis and high photocatalytic properties of stannic oxide nanoflowers