Excellent Photocatalytic Performance For Degradation Research Articles

Microscale flower-like magnesium oxide for highly efficient photocatalytic degradation of organic dyes in aqueous solution.

Flower-like MgO microparticles with excellent photocatalytic performance in degradation of various organic dyes (e.g., methylene blue, Congo red, thymol blue, bromothymol blue, eriochrome black T, and their mixture) were synthesized by a facile precipitation method via the reaction between Mg2+ and CO32− at 70 °C. The reaction time was found to be crucial in determining the final morphology of flower-like MgO. After studying the particles from time-dependent experiments, scanning electron microscope observation, Fourier transform infrared spectra and thermogravimetric analyses demonstrated that the formation of flower-like particles involved a complex process, in which agglomerates or rod-like particles with a formula of xMgCO3·yH2O (x = 0.75–0.77 and y = 1.87–1.96) were favorably formed after the initial mixture of the reactants. Owing to the chemical instability, they would turn into flower-like particles, which had a composition of xMgCO3·yMg(OH)2·zH2O (x = 0.84–0.86, y = 0.13–0.23, and z = 0.77–1.15). After calcination, the generated product not only possessed a superior photocatalytic performance in degradation of organic dyes (100 mg L−1) under UV light irradiation in contrast to other morphologies of MgO and other related state-of-the-art photocatalysts (e.g., N-doped TiO2, Degussa P25 TiO2, ZnO, WO3, α-Fe2O3, BiVO4, and g-C3N4), but also could be used for five cycles, maintaining its efficiency above 92.2%. These capacities made the flower-like MgO a potential candidate for polluted water treatment. Also, the underlying photocatalysis mechanism of MgO was proposed through radical trapping experiments.

Impact of rGO on photocatalytic performance of Cd-doped ZnO nanostructures synthesized via a simple aqueous co-precipitation route

Zinc oxide (ZnO), cadmium-doped zinc oxide (CZO), zinc oxide/reduced graphene oxide (ZnO-rGO) and cadmium-doped zinc oxide/reduced graphene oxide (CZO-rGO) nanostructures were synthesized successfully using a simple and rapid aqueous co-precipitation method at room temperature. The structure, morphologies, composition and optical properties of these samples were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Raman and UV–vis spectroscopy, respectively. In order to achieve a synergic effect, both Cd concentration, and impact of rGO on photocatalytic performance of Cd-doped ZnO nanostructures were investigated. The photocatalytic activities of the samples were investigated with the degradation of methylene blue (MB) under sunlight and showed excellent photocatalytic degradation performance for CZO-rGO (5% Cd) compared to the other samples. Facile and low-temperature synthesis process with the excellent degradation performance demonstrates that the CZO-rGO nanocomposites have a great potential for wastewater treatment applications.

Novel visible-light-driven direct Z-scheme CdS/CuInS2 nanoplates for excellent photocatalytic degradation performance and highly-efficient Cr(VI) reduction

A series of visible-light-driven direct Z-scheme CdS/CuInS2 nanoplates were fabricated by a facile one-step hydrothermal method, and the molar ratio of CdS to CuInS2 was optimized. The highest visible-light photocatalytic degradation activity of Z-scheme (1:0.03) CdS/CuInS2 heterojunction is about 4 times than that of pure CuInS2, which is due to the narrowest band gap, the largest BET surface area, the most efficient charge separation and transfer, and the synergistic effect between CdS and CuInS2. Meanwhile, Z-scheme (1:0.03) CdS/CuInS2 heterojunction also exhibits excellent photocatalytic reduction activity with almost 100% of aqueous Cr(VI) reduction efficiency in absence of hole scavengers after 60 min. The special significance is that Z-scheme (1:0.03)CdS/CuInS2 heterojunction shows excellent stability in five degradation cycles, and can effectively treat real pharmaceutical wastewater with 76.5% COD removal efficiency with aid of H2O2 in 13 h, indicating that Z-scheme CdS/CuInS2 has a promising prospect in real pharmaceutical wastewater treatment.

Preparing BiOI photocatalyst for degradation of methyl blue in wastewater

Photocatalytic oxidation on semiconductors is a green and friendly route to deal with environmental issues. Herein, a novel C/BiOIdefect photocatalyst was prepared by one-step hydrothermal method, and this nanocomposite exhibited excellent photocatalytic degradation performance under visible light irradiation. The substantially increased visible light absorption and separation of photoinduced carriers were attributed to the high photocatalytic performance. Moreover, the C/BiOIdefect also shows outstanding adsorption capacity and photochemical stability, which are also extremely important for practical application.

The band structure control of visible-light-driven rGO/ZnS-MoS2 for excellent photocatalytic degradation performance and long-term stability

ZnS-MoS2 solid solution anchored on reduced graphene oxide sheet (rGO/ZnS-MoS2) was explored as novel visible-light-driven photocatalysts, and synthesized by solvent thermal method. The light absorption intensity of rGO/ZnS-MoS2 was greatly strengthened, and rGO/ZnS-MoS2 possess modulated continuous band gaps from 3.47 to 3.56 eV by changing the Zn/Mo ratios and rGO content. Their photocatalytic activities for 2-nitrophenol degradation are dependent on the chemical composition, and the optimal 11% rGO/ZnS-MoS2 possessed the highest photocatalytic performance, which could be attributed to the most efficient charge separation, the largest specific area, and its optimized band structure. Moreover, 11% rGO/ZnS-MoS2 can effectively treat real industrial effluent with 74.05% COD removal, and maintain long-term stability without obvious decline after five use cycle.

Dual-Functional Conjugated Nanoporous Polymers for Efficient Organic Pollutants Treatment in Water: A Synergistic Strategy of Adsorption and Photocatalysis

A series of 9,9′-bifluorenylidene-based conjugated microporous/mesoporous polymers (BF-CMPs) were constructed via Suzuki polycondensation. The porosities and electronic properties of BF-CMPs can be readily tuned by selection of proper monomers. Among three BF-CMPs, Py-BF-CMP exhibited an extraordinarily high adsorption capacity (1905 mg g–1) and excellent photocatalytic degradation performance of organic dyes in water. Moreover, Py-BF-CMP featured good recyclability with both high adsorption degree (99%) and photodegradation efficiency (92%) of RhB even after 10 recycles.

String and Ball-Like TiO2/rGO Composites with High Photo-catalysis Degradation Capability for Methylene Blue

Novel three-dimensional string and ball-like titanium dioxide/reduced graphene oxide, TiO2/rGO (STG) composites were prepared using a one-step hydrolysis process followed by a low-temperature hydrothermal treatment. The STG composites exhibited excellent photo-catalytic degradation performance for methylene blue owing to a good synergistic effect between TiO2 and rGO. The STG composites with 1.0 wt% of rGO loading exhibited the highest removal rate of 86.0% for methylene blue and its reaction rate constant (5.27 × 10−3 min−1) was much higher than those of pure string and ball-like TiO2 (ST). In addition, the STG composites also showed an outstanding capability for the photo-catalysis degradation of other cationic dyes. In addition, a possible photo-catalytic degradation mechanism for the STG composite was postulated, in which $$^{ \bullet } {\text{O}}_{2}^{ - }$$ and •OH were the main oxidizing groups. This work offers new insights into a better design and preparation of novel composite materials for the removal of organic dyes.

Structure and photocatalytic performance of layered HNbWO6nanosheet aggregation

Layered HNbWO6 nanosheet aggregation (e-HNbWO6) has been assembled by HNbWO6 nanosheet via an exfoliation-restaking route. The as-prepared samples are characterized by means of powder x-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, laser Raman spectroscopy, ultraviolet-vis diffuse reflectance spectroscopy, and N2 adsorption-desorption isotherms. The photocatalytic performances of the as-prepared samples are evaluated by degradation of methylene blue (MB). The results revealed that e-HNbWO6 has a specific surface area of about 156.5 m2 g−1, and exhibits a relatively excellent photocatalytic performance for degradation of MB under UV light.

Facile room-temperature synthesis of carboxylated graphene oxide-copper sulfide nanocomposite with high photodegradation and disinfection activities under solar light irradiation

Carboxylic acid functionalized graphene oxide-copper (II) sulfide nanoparticle composite (GO-COOH-CuS) was prepared from carboxylated graphene oxide and copper precursor in dimethyl sulfoxide (DMSO) by a facile synthesis process at room temperature. The high-effective combination, the interaction between GO-COOH sheets and CuS nanoparticles, and the enhanced visible light absorption were confirmed by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and Photoluminescence (PL) spectra. The as-synthesized GO-COOH-CuS nanocomposite exhibited excellent photocatalytic degradation performance of phenol and rhodamine B, high antibacterial activity toward E. coli and B. subtilis, and good recovery and reusability. The influence of CuS content, the synergistic reaction between CuS and GO-COOH, and the charge-transfer mechanism were systematically investigated. The facile and low-energy synthesis process combined with the excellent degradation and antibacterial performance signify that the GO-COOH-CuS has a great potential for water treatment application.

Preparation of Mesoporous Bi4(GeO4)3 Microspheres from Na4Ge9O20 Template Microspheres for Photodegradation of Reactive Brilliant Red X-3B

Mesoporous materials have attracted increasing attention due to their wide application. In this paper, the Na4Ge9O20 microspheres were firstly prepared by solvothermal method. Then, the as-prepared Na4Ge9O20 microspheres were dispersed into Bi(NO3)3 solution, and the Bi4(GeO4)3 microspheres with mesoporous structure were formed due to the solid-state reaction between bismuth nitrate and Na4Ge9O20. The morphology, structure and optical properties were characterized by SEM, EDS, XRD, FITR, BET and UV–Vis diffuse reflectance analysis. The as-prepared products exhibited excellent photocatalytic performance for degradation of reactive brilliant red X-3B under the UV light irradiation. A possible photocatalytic mechanism was discussed as well.

Facile synthesis and photocatalytic performance of ZnO nanoparticles self-assembled spherical aggregates

Mesoporous ZnO spherical aggregates self-assembled with nanoparticles were prepared in a surfactant-free and template-free route under mild conditions. This ZnO spherical aggregates exhibit excellent photocatalytic degradation performance due to the small nanoparticles, high specific surface area, and porous structures, and also have easy separation and good recycling performance because of the large secondary particle size.

A novel Fe3O4@SiO2@BiOBr photocatalyst with highly active visible light photocatalytic properties

A novel Fe3O4@SiO2@BiOBr photocatalyst was synthesized through a solvothermal method with the addition of core–shell Fe3O4@SiO2 nanoparticles. The results show that the photocatalyst is flower-like microspheres with diameters ranging from 2 μm to 3 μm. The as-prepared photocatalyst shows excellent photocatalytic performance in degradation of rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm) with superior stability and reusability. The introduction of the silica interlayer can suppress the direct contact of the Fe3O4 core and BiOBr to a great extent, resulting in the increased separation efficiency of the photo-induced electron–hole pairs and then higher photocatalytic performance. Furthermore, it can be completely recovered simply by applying an external magnetic field, indicating highly potential applications in wastewater treatment without secondary pollution.

One-step synthesis of metal@titania core-shell materials for visible-light photocatalysis and catalytic reduction reaction.

Metal@TiO2 composites with a core-shell structure possess multifunctional properties. The demonstrated protocols for synthesizing such materials involve multiple steps, requiring precise control over the particle uniformity of the core and shell thickness, as well as complex surface modification. A simple approach to synthesizing metal@TiO2 hybrid nanostructures remains a great challenge. Herein, we report on a one-step method for the preparation of metal@TiO2 core-shell nanospheres, which exhibited excellent performance in photocatalytic degradation of recalcitrant organic pollutants under visible light irradiation, and in catalytic reduction of nitrophenol in water. The simple method described here represents a sustainable approach to preparing core-shell materials at low cost, involving fewer chemicals, and requiring less energy, which will make a significant contribution toward large-scale synthesis of high-performance hybrid materials for photocatalytic applications.

Hollow Nanostructures: Efficient Ag@AgCl Cubic Cage Photocatalysts Profit from Ultrafast Plasmon‐Induced Electron Transfer Processes (Adv. Funct. Mater. 23/2013)

On page 2932, Tze Chien Sum, Shuzhou Li, Zhili Dong, Zhong Chen, and co-workers report an efficient Ag@AgCl cubic cage photocatalyst with well-defined hollow interior, prepared using a watersoluble sacrificial salt-crystal-template process. The photocatalyst shows excellent photocatalytic degradation performance, which is attributed to the significant light confinement and enhancement around the Ag/AgCl interfacial plasmon hot spots, multilight-reflection inside the cage structure, and the observed ultrafast electron transfer from Ag nanoparticles to AgCl.

Sonochemical Synthesis of Ag/AgCl Nanocubes and Their Efficient Visible‐Light‐Driven Photocatalytic Performance

A novel one-step sonochemical approach to synthesize a plasmonic photocatalyst of AgCl nanocubes (ca. 115 nm in edge length) with a small amount of Ag metal species is presented. The nanoscale Ag/AgCl hybrid photocatalysts with cubic morphology are readily formed under ambient ultrasonic conditions and neither external heat treatment nor reducing agents are required. The size of the Ag/AgCl photocatalysts could be controlled by changing the concentrations of Ag(+) ions and polyvinylpyrrolidone molecules in precursor solutions. The compositions, microstructures, influencing factors, and possible growth mechanism of the Ag/AgCl hybrid nanocubes were systematically investigated. The Ag/AgCl photocatalysts show excellent photocatalytic performance for degradation of various dye molecules under visible light.