Excellent Photodegradation Performance Research Articles

TiO2 decorated BCNO nanosheet with high photocatalytic performance under visible light irradiation

Abstract In this paper, we reported a one-step and facile method to prepare boron carbon oxynitride (BCNO) nanosheet and titanium dioxide (TiO2) loaded BCNO nanocomposites. The BCNO nanosheet not only can widen the absorption range of TiO2 from ultraviolet to visible region, but also increase the photodegradation ability. The TiO2/BCNO nanocomposites have excellent photo-degradation performance on organic dyes. The TiO2-2/BCNO-2 nanocomposite can degrade almost all of methylene blue (MB) and rhodamine B (RhB) during 50 and 300 min under visible light irradiation, respectively. In addition, the photocatalytic mechanism can be explained by the electron transition process between TiO2 and BCNO.

Facile synthesis of a novel WO3/Ag2MoO4 particles-on-plate staggered type II heterojunction with improved visible-light photocatalytic activity in removing environmental pollutants.

A novel WO3/Ag2MoO4 heterojunction has been synthesized through a facile precipitation method with Ag2MoO4 particles firmly deposited on the surface of WO3 nanoplates, forming “particles-on-plate” type II heterojunction structures. This heterojunction exhibited improved photocatalytic activities for the degradation of rhodamine B (RhB), 4 chlorophenol (4-CP) and tetracycline hydrochloride (TC) under visible-light irradiation compared to pure Ag2MoO4 and WO3. In addition, the heterojunction with 10 wt% Ag2MoO4 displays the best photocatalytic performance, which was about 2 times better than that of pure WO3 or Ag2MoO4. The TC photodegradation rate reaches up to 91% within 90 min visible light irradiation. Furthermore, the photocatalytic efficiency of the Ag2MoO4/WO3 heterojunction is 1.3 times higher than that of the mixture of the two individual photocatalysts. This remarkable enhanced photocatalytic performance results from the staggered bandgap between Ag2MoO4 and WO3, which can suppress the recombination of electron–hole pairs efficiently. Moreover, based on the radical trapping experiment, the superoxide radical anions (·OH) and photogenerated holes (h+) are the crucial active oxidizing species.

A novel visible-light-driven ternary Ag@Ag2O/BiOCl Z-scheme photocatalyst with enhanced removal efficiency of RhB

A Ag@Ag2O/BiOCl composite with Ag@Ag2O cocatalyst selectively anchored on {001} facets of BiOCl nanosheets exhibits excellent photodegradation performance.

Facile synthesized low-cost MoS2/CdS nanodots-on-nanorods heterostructures for highly efficient pollution degradation under visible-light irradiation

Semiconductor-based photocatalytic degradation of organic pollutant shows bright prospect and has potential to address the global environmental issues. But the low efficiency, currently, is still an obstacle, which stems from ultrafast charge recombination. In this manuscript, MoS2/CdS nanodots-on-nanorods heterostructures were successfully synthesized via a novel but facile one-pot solvothermal approach with less time and energy consumption. The in-situ synthesized MoS2/CdS heterostructures with intimate interface between MoS2 and CdS facilitate photogenerated charge transportation and separation. Besides, the discrete distribution of MoS2 nanodots on CdS nanorods offers a great many active sites for organic dye degradation. As a result, the optimized MoS2/CdS hybrid shows an excellent photodegradation performance of rhodamine B (RhB) with 99.11% of RhB decomposition in 45 min, which is the advanced among all the similar catalytic systems. Our findings will give inspiration for developing low-cost and efficient catalysts for photodegradation of organic pollutants.

One-step synthesis of Cu2O@carbon nanocapsules composites using sodium alginate as template and characterization of their visible light photocatalytic properties

A One step-synthesis method was developed to fabricate composite photocatalysts from cuprous oxide and carbon nanocapsules (Cu2O/CNC), using sodium alginate as a template. Carbon nanocapsules and nanosheets were self-generated by calcination in the presence of Cu2+ species. And Cu2O particles with a diameter of 20–50 nm were distributed in the carbon nanocapsules or on the surface of the carbon nanosheets. The carbon nanomaterials provide a large surface area, which makes it easier for Cu2O to immobilize dye molecules through hydrogen bonding. Batch adsorption and degradation experiments were carried out using catalysts synthesized under different conditions, including sodium alginate fraction, crosslinker concentration, and precipitant concentration. The results showed that the Cu2O/CNC composite catalysts exhibited excellent photodegradation performance under visible light, removing 90% of methyl red in 120 min. The removal efficiency and photodegradation rate were affected significantly by a) the specific area of the catalysts; b) the morphologies of Cu2O and carbon nanomaterials; c) the synergy between Cu2O and carbon nanomaterials. A detailed mechanism for the enhancement of photocatalytic activity towards degradation of methyl red is proposed.

A novel and highly efficient photocatalytic degradation of malachite green dye via surface modified polyacrylonitrile nanofibers/biogenic silica composite nanofibers

In this work surface modified polyacrylonitrile nanofibers/biogenic silica composites were investigated for their promising and efficient photocatalytic degradation of malachite green (MG) dye. This photocatalyst was based on polyacrylonitrile (PAN) nanofibers fabricated using electrospinning technique, then crosslinked with two kinds of biogenic silica, diatomite and rice husk nanosilica. The photocatalytic activities of MG dye were compared for the two biogenic silica. The prepared membranes was analyzed using SEM, TEM, EDAX, FTIR, and XRD techniques. The photocatalysis performance investigations of malachite green were carried out under visible light illumination in aqueous solutions. Moreover, several factors affecting the degradation were studied including; dye concentration, solution pH, and irradiation time. The results indicated that the investigated composite nanofibers have excellent photodegradation performance for Malachite green. The highest photodegradation efficiency of the MG was obtained at pH 7 and it is relatively a very fast process.

Hydrothermally synthesized highly dispersed Na2Ti3O7 nanotubes and their photocatalytic degradation and H2 evolution activity under UV and simulated solar light irradiation

Photocatalytic water splitting technologies are currently being considered for alternative energy sources. However, the strong demand for a high H2 production rate will present conflicting requirements of excellent photoactivity and low-cost photocatalysts. The first alternative may be abundant nanostructured titanate-related materials as a photocatalyst. Here, we report highly dispersed Na2Ti3O7 nanotubes synthesized via a facile hydrothermal route for photocatalytic degradation of Rhodamine B (RhB) and the water splitting under UV-visible light irradiation. Compared with commercial TiO2, the nanostructured Na2Ti3O7 demonstrated excellent photodegradation and water splitting performance, thus addressing the need for low-cost photocatalysts. The as-synthesized Na2Ti3O7 nanotubes exhibited desirable photodegradation, and rate of H2 production was 1,755 μmol·g−1·h−1 and 1,130 μmol·g−1·h−1 under UV and simulated solar light irradiation, respectively; the resulting as-synthesized Na2Ti3O7 nanotubes are active in UV light than that of visible light response.

Facile Synthesis of {101}, {010} and [111]‐Faceted Anatase‐TiO2 Nanocrystals Derived from Porous Metatitanic Acid H2TiO3 for Enhanced Photocatalytic Performance

AbstractThe cuboid‐like anatase TiO2 nanocrystals with co‐exposed {101}/[111]‐facets and the irregular anatase TiO2 nanocrystals with co‐exposed {101}/{010} facets were hydrothermally synthesized by using porous metatitanic acid H2TiO3 as the precursor and the HF, H2O2 and NH3⋅H2O as the capping agent and solvent. The as‐prepared anatase TiO2 nanocrystals were characterized by the powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high‐resolution transmission electron microscopy (HRTEM), selected‐area electron diffraction (SAED) and Nitrogen adsorption/desorption measurements. The transformation from the porous structure of metatitanic acid H2TiO3 to anatase TiO2 nanocrystals may experience three types of reactions including dehydration reaction from [TiO3]2− layers, [TiO6]8− octahedral monomers along the edge‐shared oxygen atoms, the formation of anatase nucleus, and the growth of anatase nucleus along the [101]‐direction and [011]‐direction (or [‐10‐1]‐direction and [0‐1‐1]‐direction) during the hydrothermal reaction process. Furthermore, the photocatalytic activities of the as‐prepared anatase nanocrystals were evaluated by the photocatalytic degradation of the typical carcinogenicity pollutant Rhodamine B (RB) under UV‐light irradiation at room temperature in air. The T180‐TiO2 nanocrystals exhibits the most excellent photodegradation performance than the T150‐TiO2, T160‐TiO2, T180‐TiO2 anatase nanocrystals and the commercially available P25‐TiO2 nanocrystals for the degradation amount of RB per unit surface area of catalyst (mg(RB) per m2 (TiO2 surface area)), which can be ascribed to its high percentage of the {010}/[111]‐crystal facets.

Surfactant free synthesis of Sr2CeO4 nanostructures and their application in removal of organic pollutions

In current work, surfactant free synthesis of Sr2CeO4 nanostructures by co-precipitation process were reported. This method require lower firing temperature (700 °C) compare to the previous reports (above 1000 °C). This study shows that by controlling the reaction conditions such as kind of precipitating agent, surfactant and calcination temperature, the Sr2CeO4 nanostructures with various morphologies were prepared. Up to now, luminescence properties of Sr2CeO4 structures received great attention, while we focused on the photocatalytic activity of Sr2CeO4 nanostructures. Results show that the Sr2CeO4 nanostructures have exhibited excellent photodegradation performance of Acid red 88 azo dye as water pollutants under UV light irradiation.

Cellulose acetate-based SiO2/TiO2 hybrid microsphere composite aerogel films for water-in-oil emulsion separation

The cellulose acetate (CA)/SiO2-TiO2 hybrid microsphere composite aerogel films were successfully fabricated via water vapor-induced phase inversion of CA solution and simultaneous hydrolysis/condensation of 3-aminopropyltrimethoxysilane (APTMS) and tetrabutyl titanate (TBT) at room temperature. Micro-nano hierarchical structure was constructed on the surface of the film. The film could separate nano-sized surfactant-stabilized water-in-oil emulsions only under gravity. The flux of the film for the emulsion separation was up to 667 L m−2 h−1, while the separation efficiency was up to 99.99 wt%. Meanwhile, the film exhibited excellent stability during multiple cycles. Moreover, the film performed excellent photo-degradation performance under UV light due to the photocatalytic ability of TiO2. Facile preparation, good separation and potential biodegradation maked the CA/SiO2-TiO2 hybrid microsphere composite aerogel films a candidate in oil/water separation application.

One-pot synthesis of bismuth silicate heterostructures with tunable morphology and excellent visible light photodegradation performances

Construction of a heterostructure to prolong the life of electron-hole pairs is a very important approach to endow it with excellent photodegradation performances. Particularly, one-pot synthesis of heterostructures with the same component but different crystal structures to form a proper band gap is still challenging. Herein, bismuth silicate (BSO) heterostructures are synthesized using a one-pot hydrothermal approach without adding any other inorganic components. The crystal phase, morphology, surface state, and photochemical properties of the BSO materials are precisely tuned to fabricate two kinds of bismuth silicate heterostructures: rod-like Bi2SiO5/Bi12SiO20 and flower-like Bi2SiO5/Bi4Si3O12 heterostructures. Thanks to the two heterostructures and clean surface, the optimized BSO material exhibits a highly active photocatalytic performance with a remarkable cycling stability. It photodegrades Rhodamine B under visible light irradiation as fast as 15min with the reaction rate constants k and ks to be 0.399min−1 and 0.698min−1Lm−2, respectively, which is up to 189 times faster than reported.

Facile preparation 3D ZnS nanospheres-reduced graphene oxide composites for enhanced photodegradation of norfloxacin

We reported the fabrication of 3D ZnS nanospheres on the reduced graphene oxide (RGO) nanosheet by a facile hydrothermal treatment. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic ability of the as-prepared ZnS nanospheres on graphene sheets was investigated by using norfloxacin as a model contaminant. The result shows that compared to the pure ZnS under same conditions, the ZnS-reduced graphene oxide composites exhibit excellent photodegradation performance for the photodegradation of non-biodegradable norfloxacin (NOR) antibiotic, the remarkable property could be attributed to the function of RGO what provided efficient photoinduced charge separation and transportation from the semiconductor. Therefore, the ZnS-reduced graphene oxide composites photocatalytic superiority would be used to the application in the area of photocatalytic degradation hazard pollutants.

Nanocrystalline TiO₂ Composite Films for the Photodegradation of Formaldehyde and Oxytetracycline under Visible Light Irradiation.

In order to effectively photodegradate organic pollutants, ZnO composite and Co-B codoped TiO2 films were successfully deposited on glass substrates via a modified sol-gel method and a controllable dip-coating technique. Combining with UV–Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL) analyses, the multi-modification could not only extend the optical response of TiO2 to visible light region but also decrease the recombination rate of electron-hole pairs. XRD results revealed that the multi-modified TiO2 film had an anatase-brookite biphase heterostructure. FE-SEM results indicated that the multi-modified TiO2 film without cracks was composed of smaller round-like nanoparticles compared to pure TiO2. BET surface area results showed that the specific surface area of pure TiO2 and the multi-modified TiO2 sample was 47.8 and 115.8 m2/g, respectively. By degradation of formaldehyde and oxytetracycline, experimental results showed that the multi-modified TiO2 film had excellent photodegradation performance under visible light irradiation.

Novel carboxylated graphene oxide‐CuS‐Ag nanocomposite glass coating for organic degradation under solar light

AbstractBACKGROUDRecently, semiconductor‐mediated heterogeneous photocatalysis has gained recognition as an effective treatment method for the removal of emerging organic contaminants (EOCs) from wastewater. The advantages of such technology include higher reaction rates for pollutant removal, complete mineralisation of the contaminants into harmless substances, e.g. water and carbon dioxide. Here, this study synthesized a hybrid multifunctional nanocomposite (GO‐COOH‐CuS‐Ag) via a facile method by integrating semiconductor copper sulfide (CuS) nanoflakes, carboxylic acid functionalised graphene oxide (GO‐COOH) sheets, and silver (Ag) nanoparticles, with the aim to enhance their EOCs photodegradation and antibacterial applications under solar light irradiation.RESULTSThe crystal phase, optical properties and morphology of the obtained composite were characterized using various characterization methods. The as‐synthesized GO‐COOH‐CuS‐Ag nanocomposites were transformed and applied on glass via a glass coating method aimed at facilitating their practical applications in photodegradation of emerging organic contaminants (EOCs) and disinfection for water treatment under solar light irradiation. The glass coatings had excellent photodegradation and antibacterial performance with good stability and repeatability. It was also found that synergistic reactions existed among CuS, Ag and GO‐COOH, and the mechanisms of charge transfer and photo‐disinfection were systematically investigated.CONCLUSIONThe results clearly demonstrate its high performance potential in photodegradation and photo‐disinfection processes with the advantage of simplifying recovery and reuse in comparison with powdered forms, and reducing problems including the agglomeration of powdered particles that may cause blockages. © 2017 Society of Chemical Industry

Silver Silicate@Carbon Nanotube Nanocomposites for Enhanced Visible Light Photodegradation Performance

The abilities of adsorption and separation of electron hole pairs are two important factors in photodegradation, and a balance between them is required to obtain an excellent photodegradation performance. As a new photocatalyst, silver silicate has a poor conductivity that hinders its photodegradation ability. Herein, silver silicate (AgSiOx)@carbon nanotube (CNT) and AgSiOx@reduced graphene oxide (RGO) nanocomposites are prepared for the first time to improve the photodegradation performance of AgSiOx. The influences of CNT and RGO contents on improving the photodegradation efficiency of AgSiOx are different due to the differences in the concentration of oxygen-containing groups and the electrical conductivity. The photodegradation efficiency of AgSiOx@CNT nanocomposites first increases and then decreases with increasing the concentration of CNTs, while the removal efficiency of pollutants by AgSiOx@RGO nanocomposites increases with the GO concentration owing to the residual oxygen-containing functional ...

Enhanced Photocatalytic Activity Based on Composite Structure with Downconversion Material and Graphene

TiO2 nanorods arrays (TiO2 NRAs):Eu3+, Tb3+ decorated with Cs2CO3/CdS grown on carbon textiles coated with a TiO2–graphene (TiO2-G) thin film (TiO2-G/TiO2 NRAs:Eu3+, Tb3+/Cs2CO3/CdS) was fabricated. The as-prepared sample exhibits an excellent photodegradation performance under xenon (Xe) lamp light irradiation. The result indicates that the presence of Eu3+, Tb3+ can be excited by ultraviolet light to produce a high intensity visibe light absorbed by CdS, which can generate more photogenerated electron hole pairs. In addition, the presence of graphene is an important factor in accelerating the transferring of photogenerated electron to carbon textiles for photocatalytic reaction. This work can offer an alternative route for designing a hybrid structure system to utilize effectively broad-spectrum solar light and suppress the recombination of photogenerated electron–hole pairs.

Facet-Controlling Agents Free Synthesis of Hematite Crystals with High-Index Planes: Excellent Photodegradation Performance and Mechanism Insight.

Hematite (α-Fe2O3) crystals with uniform size and structure are synthesized through very facile one-pot hydrothermal methods without any additive. The as-synthesized sub-micrometer-sized α-Fe2O3 crystals with small surface areas perform superb visible light photodegradation activities, even much better than most other α-Fe2O3 nanostructures with large surface areas. Profound mechanism analyses reveal that the microwave-assisted hydrothermal (Mic-H) synthesized α-Fe2O3 is enclosed by 12 high-index {2-15} facets. The structure and the low unoccupied molecular orbital (LUMO) of the high-index planes result in the excellent photocatalytic activity. This is the first report on the formation of {2-15} plane group of hematite, and the synthesis of the hematite particles with the {2-15} planes is very simple and no any facet-controlling agent is used. This study may pave the way to further performance enhancement and practical applications of the cheap hematite materials.

Fabrication of g-C 3 N 4 /TiO 2 composite photocatalyst with extended absorption wavelength range and enhanced photocatalytic performance

Abstract Not only for utilizing both ultraviolet (UV) and visible light but also for enhancing photoinduced carriers separation capability, a composite photocatalyst composed of graphite-like carbon nitride (g-C 3 N 4 ) and TiO 2 has been successfully prepared by an acetic acid assisted sol–gel method combined with calcination process. The as-prepared g-C 3 N 4 /TiO 2 composite photocatalyst was characterized by using XRD, SEM, TEM, XPS, FT-IR spectra, UV-DRS and TGA. Combined XRD results with SEM images, it indicated that the obtained anatase TiO 2 nanoparticles dispersed well on the surface of g-C 3 N 4 sheets and the aggregation degree of TiO 2 nanoparticles could be effectively alleviated due to the introduction of g-C 3 N 4 . The results of UV-DRS further displayed that the optical absorption edge of g-C 3 N 4 /TiO 2 composites had an obvious red shift to the longer wavelength in comparison with pure TiO 2 . Profiting from the above-mentioned advantages, g-C 3 N 4 /TiO 2 composite showed excellent photocatalytic performance. Under visible light irradiation, all g-C 3 N 4 /TiO 2 composite samples had more excellent photodegradation performance than pure g-C 3 N 4 or TiO 2 , and the pseudo-first-order kinetic constant of methyl orange (MO) degradation on optimal g-C 3 N 4 /TiO 2 composite was 2.80 times as great as that on pure g-C 3 N 4 . The photodegradation performance of optimal g-C 3 N 4 /TiO 2 composite was also investigated under UV–vis light irradiation. Compared with the pure phase (TiO 2 or g-C 3 N 4 ), the composite photocatalytic capability was remarkably enhanced by coupling TiO 2 with g-C 3 N 4 , which mainly benefited from the effective separation of photoinduced electron–hole pairs and the extended optical absorption range, both owing to the heterojunction built-in between g-C 3 N 4 and TiO 2 .

Photoluminescence Properties and Photocatalytic Performance of Different Size ZnO Nanoparticles Decorated Graphene Oxide.

We synthesized the hybrid structure of the graphene oxide (GO) sheet and the size-controlled ZnO nanoparticles. The ZnO quantum sizes were confirmed from UV-vis spectrophotometry and TEM results. The ZnO quantum dot exhibited a stable broad and strong photoluminescence (PL) emission which is broader with the increase of ZnO nanoparticle size. The hybrid ZnO/GO results an abrupt decrease of PL emission and the excellent photodegradation performance of methylene blue under UV-light irradiation. A considerable increase of the photodegradation rate with decreasing ZnO nanoparticle size is due to the enhancement of ZnO surface interaction and the improvement of electron transfer at the ZnO/GO interface.

Study of a Magnetic Photocatalyst Based on Hemin with Axial Ligand and its Degradation under Visible Light

An investigation was conducted on hemin modified with axial ligand loaded onto magnetic carriers which created a kind of visible-light activated photocatalyst with good magnetic property. This photocatalyst exhibits excellent photo-degradation performance and can be readily reclaimed in the degradation of bis-phenol A (BPA) in aqueous solution under visible light. The catalysts were characterized by thermal gravimetric analysis (TG), transmission electron microscopy (TEM), magnetometer (VSM) and IR spectra. The effects of different operation parameters on the photocatalytic reaction have also been investigated. The highest degradation ratio reached up to 94.75% after 6 hours under optimized operation conditions. Moreover, the photocatalyst could be readily reclaimed by magnetic separation with an external magnetic field and when it was reused for 5 times under the same conditions, the degradation ratio of BPA solution during the last time was still higher than 90%. Possible mechanism on BPA degradation was also investigated based on a series of control experiments. The main intermediate of BPA degradation was monitored by GC/MS analysis.