Synthesis and characterization of Ag/TiO2-B nanosquares with high photocatalytic activity under visible light irradiation

Square-like B doped TiO₂ nanocrystals were first synthesized by a mild solvothermal method with H₃BO₄ and titanium isopropoxide as the precursors, and isopropyl alcohol as reaction medium. Then, Ag nanoparticles were deposited on TiO₂-B nanosquares by photo-deposition. The as-synthesized products have been investigated by photocatalytic reaction test and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra (DRS). The results showed that boron was successfully doped into TiO₂ nanosquares under solvothermal condition. The obtained Ag/TiO₂-B composite showed high efficiency in degradation of acid orange II under visible light irradiation. The high photocatalytic performance could be attributed to the synergistic effect of B doping and the plasmon photocatalysis role of the deposited silver nanoparticles over TiO₂.     

Synthesis and enhanced photocatalytic activity of regularly shaped Cu2O nanowire polyhedra

A series of unique nanowire superstructures, Cu2O nanowire polyhedra, have been synthesized through a cost-effective hydrothermal route. Three types of nanowire polyhedra, namely octahedra, concave octahedra, and hexapods, were formed in high morphological yields (90%) by reducing cupric acetate with o-anisidine or o-phenetidine in the presence of carboxylic acids. The architectures of these Cu₂O nanowire polyhedra were examined by electron microscopy, which revealed ordered, highly aligned Cu₂O nanowires within the polyhedral outlines. The growth of the Cu₂O nanowire polyhedra is controlled by the orientation and growth rates of the nanowire branches which are adjusted by addition of carboxylic acids. Compared to the Cu₂O samples reported in the recent literature, the Cu₂O nanowire octahedra exhibit notably enhanced photocatalytic activities for dye degradation in the presence of H₂O₂ under visible light, probably due to the high-density charge carriers photoexcited from the branched nanowires with their special structures. Additionally, the discussion in the recent literature of the photocatalytic activity of Cu₂O in the absence of H₂O₂ for direct photodegradation of dyes seems questionable.     

Enhanced photocatalytic performance of Fe-doped SnO2 nanoarchitectures under UV irradiation: synthesis and activity

A facile, sol–gel method has afforded highly crystalline, Fe-doped SnO₂ nanoarchitectures with efficient photocatalytic degradation of rhodamine B (RhB) under ultraviolet irradiation. The effects of iron modification to tin dioxide were investigated. The structural properties were characterized by powder X-ray diffraction, gas sorption (adsorption/desorption) techniques, scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy (EDS). The photocatalytic activity of these materials was studied by examining the degradation of RhB with pure SnO₂ and each Fe modified sample (3 and 5 %), all annealed at 350 °C. Diffraction results reveal that the synthesized nanocrystals are ~3 nm in diameter. Gas sorption analyses detail high-specific surface areas (>330 m² g^?1). Electron microscopy studies illustrate the enhanced porosity brought on through annealing. EDS confirms the presence of Fe in the most active Fe-modified SnO₂ sample. It is found that the 5 % Fe-modified SnO₂ degrades RhB by more than half after 2 h.     

TiO2纳米带制备、表征及光催化性能

采用简单的水热反应以及后续的热处理,制备了大量的TiO2纳米带。通过XRD、SEM、TEM以及UV-Vis对产物进行表征和分析,并以甲基橙作为目标降解物,对退火后的产物进行了光催化性能测试。结果表明,所制备的样品在600℃热处理3h后,样品为锐钛矿相与TiO2(B)相的混晶相。退火以后,带的形态保持较好,带宽约60nm。室温下,所制备的混晶TiO2对甲基橙具有良好的紫外光降解能力,60min后降解度达96%。     

Synthesis and photocatalytic activity of nanocrystalline TiO2-SrO composite powders under visible light irradiation

Nano-sized homogeneously distributed TiO₂-20, -40, -60 wt.% SrO composite powders were successfully synthesized by a sol-gel method. The as-received amorphous TiO₂—20 wt.% SrO composite powders were crystallized with anatase TiO₂ at around 750 °C. As calcination temperatures increased, the anatase TiO₂ crystalline phase was transformed to rutile TiO₂ at about 900 °C, whereas nano-sized, squarish SrTiO₃ phase was detected. The peaks obtained after calcining at 1050 °C mainly exhibited the rutile TiO₂ and SrTiO₃ phases. However, a small number of SrO₂ peaks were also detected. For the comparison of photocatalytic activity depending on light sources, TiO₂-SrO composite powders were tested in phenol degradation. TiO₂-60 wt.% SrO composite powder showed good visible light photoactivity for the photo-oxidation of phenol.     

Photoinduced charge property of nanosized perovskite-type LaFeO3 and its relationships with photocatalytic activity under visible irradiation

In this paper, ABO₃-type perovskite LaFeO₃ nanosized photocatalysts were synthesized by a sol-gel method, using citric acid (HOOCCH₂C(OH)(COOH)CH₂COOH) as complexing reagent and La(NO₃)₃·6H₂O and Fe (NO₃)₃·9H₂O as raw materials. The as-prepared samples also were characterized by several testing techniques, such as thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET), infrared spectrum (IR), ultraviolet-visible diffuse reflection spectrum (UV-vis DRS), photoluminescence spectrum (PL), surface photovoltage spectroscopy (SPS) and electrical field induced surface photovoltage spectroscopy (EFISPS). The sample activity of different LaFeO₃ nanoparticles for degrading Rhodamine B solution under visible irradiation (λ > 400 nm) was evaluated. The effects of thermal treatment temperature on photoinduced charge property and photocatalytic activity were mainly investigated, together with their relationships. The results show that the LaFeO₃ sample calcined at 500 °C exhibits higher activity, and the activity decreases with increasing calcination temperature, which is in good agreement with the characterization results. The weaker is the PL and SPS signal, the higher is the photocatalytic activity. Moreover, the activity of all as-prepared LaFeO₃ samples is higher than that of international P-25 TiO₂ under visible irradiation.     

花状Bi_2WO_6光催化剂的制备及性能研究

采用简单水热法制备了具有三维花状结构的斜方晶Bi2WO6光催化剂,利用XRD、SEM、BET等分析技术对催化剂的结构和形貌进行了表征。考察了反应时间、Bi2WO6加入量、染料罗丹明B初始浓度和光源对罗丹明B光催化降解效果的影响。实验结果表明,180℃下水热12h合成的Bi2WO6催化剂,在加入量为2g/L,溶液pH为6.5,并以模拟日光500W氙灯(不加滤光片)为光源,光照30min内,对浓度为10mg/L的罗丹明B去除率最高达99.6%。水热制备的花状Bi2WO6具有较高的光催化活性。     

Synthesis, characterization and its visible-light-induced photocatalytic property of carbon doped ZnO

Carbon-doped ZnO was prepared by calcination of organic zinc compound synthesized by the reaction between ZnCl₂ and glycol. It was characterized by thermal analysis, XPS, XRD, DRUV-vis, and PL. The results show that substitution of lattice oxygen by carbon in ZnO results in significantly extending for its optical response from UV to visible region. The photocatalytic test shows that it efficiently photomineralize formaldehyde to CO₂ under irradiation of indoor fluorescent lamp and its photocatalytic activity is much better than nitrogen-doped TiO₂.     

Photocatalytic degradation of rhodamine B by Bi2O3/Cs3PW12O40 composite under visible-light irradiation and its enhanced photocatalytic activity

Journal of Materials Science: Materials in Electronics - A novel Bi2O3/Cs3PW12O40 (Bi2O3/CsPW) composite was prepared by depositing Bi2O3 on the surface of spherical Cs3PW12O40. The synthesized...     

Synthesis, characterization and photocatalytic property of nano-sized Zn2SnO4

Nano-sized Zn₂SnO₄ materials have been synthesized using the coprecipitation method. The synthetic conditions and the calcination behaviors of nano-sized Zn₂SnO₄ materials have been studied. The nano-sized Zn₂SnO₄ materials have been characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry and differential thermal analysis (TG-DTA) and specific surface area. As a result, the kinetic grain growth equation for nano-sized Zn₂SnO₄ can be expressed as D ^4.78 = 9.12 × 10²³ t exp(–40.6 × 10³/T), with an activation energy for grain growth of Q = 337.9 KJ/mol. The nano-sized Zn₂SnO₄ materials have been used as photocatalysts to decompose benzene in water solution. The results show that Zn₂SnO₄ can photocatalytically decompose benzene, and the photocatalytic capacity for Zn₂SnO₄ relates to the grain size, which is discussed in terms of the surface effect and the quantum size effect.     

Synthesis,characterization and photocatalytic activity of ZnO-SnO2 nanocomposites

Nanocomposites of coupled ZnO-SnO₂ photocatalysts were synthesized by the coprecipitation method and were characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, surface area analyzer and scanning electron microscopy. Their photocatalytic activity was investigated under UV, visible and solar light and evaluated using methylene blue (MB) as a model pollutant. The performance of the coupled ZnO-SnO₂ photocatalysts was found to be related to the Zn/Sn molar ratio and to the calcination conditions. The photocatalyst with a Zn/Sn molar ratio of 1:0.05 calcined at 600 °C for 2 h showed the maximum degradation rate of MB under different lights used. Its photocatalytic activity was found to be about two times that of ZnO and about 10 times that of SnO₂ which can be explained by the heterojunction effect. Charge separation mechanism has been studied.     

Synthesis,characterization, and its photocatalytic activity of double-walled carbon nanotubes-TiO2 hybrid

Double-walled carbon nanotube (DWCNT)-TiO₂ hybrid was prepared by hydrothermal method and characterized by X-ray diffraction, electron microscopy, N₂-adsorption analysis, Raman spectroscopy, Fourier transform infrared spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of DWCNT-TiO₂ hybrid was tested by the photocatalytic degradation of sulfathiazole. The experimental results showed that the introduction of the DWCNTs provides DWCNT-TiO₂ hybrid with visible light-induced photoactivity and a large surface area. The DWCNTs were coated with TiO₂ nanoparticles, which generated an intimate contact between the DWCNTs and TiO₂. The DWCNT-TiO₂ hybrid showed an excellent visible-light-induced activity, compared with multi-walled carbon nanotube-TiO₂ and single-walled carbon nanotube-TiO₂ hybrids, which can be attributed to the unique electronic structure of the DWCNTs that can work well as not only a photosensitizer but also an electron conductor. In addition, DWCNT-TiO₂ hybrid with the DWCNTs of long length showed higher degradation efficiency than that with the short length.     

Synthesis of Se nanoparticles by using TSA ion and its photocatalytic application for decolorization of cango red under UV irradiation

In this study, we describe a size-controlled synthesis of selenium nanoparticles based on the reduction of selenious acid (H₂SeO₃) by UV-irradiated tungstosilicate acid (H₄SiW₁₂O₄₀, TSA) solution which serves both as reducing reagent and stabilizer. The nanoparticles are characterized by ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), the Raman spectra, transmission electron microscopy (TEM) and Zetasizer, respectively. The characteristic catalytic behavior of the Se nanoparticles is established by studying the decolorization of cango red in the presence of UV light. It is obvious that selenium catalyzes the reaction efficiently. The results show that the rate of dye decolorization varies linearly with the nanoparticle concentration and the rate of dye decolorization decreases with the size of the Se nanoparticles increasing.     

Synthesis and photocatalytic property of SnO2/TiO2 nanotubes composites

SnO2/TiO2 nanotubes composite photocatalysts with different SnO2 contents were successfully synthesized by means of a simple solvothermal process. The synthesized products were characterized physically by X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM). The composite photocatalysts can not only make the target pollutant, methylene blue (MB), adsorbed at a high concentration level around the surface of the composites but also decrease the recombination rate of electron-hole pairs so as to achieve good photocatalytic performance. The effect of SnO2 contents on the photocatalytic activities of the composites was also investigated. The results showed that the SnO2/TiO2 nanotubes composite photocatalyst with 5 wt.% SnO2 loading had the highest photocatalytic efficiency.     

Facile synthesis of Ag/ZnO heterostructures assisted by UV irradiation: Highly photocatalytic property and enhanced photostability

We report a new method to synthesize Ag/ZnO heterostructures assisted by UV irradiation. The formation of Ag/ZnO heterostructures depends on photogenerated electrons produced by ZnO under UV light to reduce high valence silver. Functional property of the Ag/ZnO heterostructures is evaluated by photodegradation of methylene blue (MB) under UV illumination. Results of photodegradation tests reveal that the optimal photocatalytic activity of as-syntheszied samples is about 1.5 times higher than the pure ZnO synthesized in the same condition or commercial TiO₂ (P-25), showing the advantage of the unique structure in the Ag/ZnO heterostructure. Besides, due to the reduced activation of surface oxygen atom, photocatalytic activity of the photocatalysts has no evident decrease even after three recycles.     

Cu/ZnO复合材料的制备及光催化性能研究

采用化学沉积法,在纳米ZnO种子的表面沉积金属Cu纳米颗粒合成复合材料。利用XRD、FESEM、TEM和TGA对样品成分、形貌和结构进行了表征分析,并测试了样品的光催化性能。结果表明,Cu纳米颗粒成功负载于ZnO纳米粒子表面。对于Cu与ZnO合成的复合催化剂,金属Cu的含量有一个最佳的范围,此时催化剂的光催化性能优于纯ZnO。当Cu2+的加入量为38.6%(质量分数)时,复合颗粒的光催化性能在紫外光和可见光光源下均达到最优。     

Synthesis and characterization of Ag3PO4/multiwalled carbon nanotube composite photocatalyst with enhanced photocatalytic activity and stability under visible light

A novel Ag₃PO₄/multiwalled carbon nanotube (Ag₃PO₄/MWCNT) composite has been prepared by a simple precipitant approach. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, UV–Vis diffuse reflectance, and Raman spectroscopy. It is found that the MWCNTs are well deposited on Ag₃PO₄ nanoparticles. The Ag₃PO₄/MWCNT composite with MWCNT content of 1.4 wt% exhibits optimal photocatalytic activity under visible light. The rate constant of MO degradation over Ag₃PO₄/1.4 wt% MWCNT is 5.84 times that of pure Ag₃PO₄. Compared with pure Ag₃PO₄, the incorporation of MWCNTs not only significantly enhances the photocatalytic activity but also improves the structural stability of Ag₃PO₄, suggesting that the synergistic effects take place in the composite. The improvement is attributed to the conductive structure supported by MWCNTs, which favors electron–hole separation and the removal of photogenerated electrons from the decorated Ag₃PO₄. A possible photocatalytic mechanism of the Ag₃PO₄/MWCNT photocatalyst was assumed as well.