In-situ growth of large-area monolithic Fe_2O_3/TiO_2 catalysts on flexible Ti mesh for CO oxidation

In this study, we reported the in-situ fabrication of a series of Fe_2O_3/TiO_2 monolithic catalysts on flexible Ti mesh via plasma electrolytic oxidation process, hydrothermal reaction and chemical bath deposition(CBD) method. The morphology tailoring of Fe_2O_3 nanostructures finds that Fe_2O_3 nanosheets supported on TiO_2 exhibit superior catalytic performance with a complete oxidation of CO at 260°C. The catalytic stability test indicates that the in-situ grown Fe_2O_3/TiO_2 catalysts own outstanding performance for continuous CO oxidation due to the strong substrate adhesion without mass loss. The microstructures and interfaces of Fe_2O_3/TiO_2 catalysts are well studied using series of characterization techniques. The in-situ preparation strategy of metal oxide catalysts in this work will open up more opportunities for the rational design of variety of monolithic catalysts used for CO oxidation, de-NOx, three-way catalysis and other related application in industry.     

Solvothermal synthesis of Ag/ZnO micro/nanostructures with different precursors for advanced photocatalytic applications

Micro/nanostructured systems based on metallic oxide (ZnO) with noble metal (Ag) on the surface (Ag/ZnO) are synthesized by solvothermal method from zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O), zinc acetate dehydrate (Zn(CH₃COO)₂·2H₂O), zinc acetylacetonate hydrate (Zn(C₅H₇O₂)₂·xH₂O) and silver nitrate (Ag(NO₃)) as precursors. In these systems, polyvinylpyrrolidone (PVP) is used as surfactant for controlling particle morphology, size and dispersion. The obtained materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), UV–vis diffuse reflectance spectroscopy (DRS), N₂ gas adsorption–desorption (BET) and Raman spectroscopy (RS). By XRD results, all major peaks are indexed to the hexagonal wurtzite-type structure of the ZnO and samples with noble metal, extra diffraction peaks are detected which correspond to the face-centered-cubic (fcc) structure of the metallic Ag. Depending on used precursor, different morphologies have been obtained. Mainly, ZnO prims-like rods – NRs (with 0.8 ? aspect ratio ? 3.4) – have been observed. Quasi-spherical particles of metallic Ag (with diameters between 558 ± 111 μm and 22 ± 1 nm) have been detected on the ZnO surface. Photocatalytic results (all samples studied >30% MB degradation) verify the important effect of surfactant and the viability of synthesized Ag/ZnO micro/nanocomposites for environmental applications.     

Sol-gel synthesis,structural and enhanced photocatalytic performance of Al doped ZnO nanoparticles

In this research ZnO and Zn_1?x Al_xO (x = 1, 3, 5, 7% mol) nanoparticles were synthesized by sol-gel method. The effect of Al concentration on the structure, morphology, absorption spectra and photocatalytic properties investigated by using X-ray, TEM, EDS and UV–Vis spectrophotometer approaches. Hexagonal, spherical and rod-like structure was achieved as the dominant structure for undoped nanoparticles, low and high concentrations of doped Al, respectively. Photocatalytic activity of nanoparticles was measured by degradation of methyl orange as a pollutant under radiation of ultraviolet (UV). The experimental test results indicate that the best photocatalytic performance is at of 5% of Al. Furthermore, the doped ZnO nanoparticles have more activity in visible area compared with undoped nanoparticles. The absorption amount in this area increases by raising the Al concentrations. Furthermore, the band gap of the particles decreases from 3.22 eV to 2.93 eV by increasing Al percentage.     

Templated photocatalytic synthesis of well-defined platinum hollow nanostructures with enhanced catalytic performance for methanol oxidation

Hollow metallic nanostructures exhibit important applications in catalysis, sensing, and phototherapy due to their increased surface areas, reduced densities, and unique optical and electronic features. Here we report a facile photocatalytic process to synthesize and tune hollow platinum (Pt) nanostructures. Through hierarchically structured templates, well-defined hollow Pt nanostructures are achieved. These nanostructures possess interconnected nanoporous framework as shell with high surface area for enhanced catalytic performance/mass transport for methanol oxidation.     

Sonochemical synthesis and photocatalytic activity of meso- and macro-porous TiO(2) for oxidation of toluene

Meso-and macro-porous TiO(2) were synthesized by ultrasonic induced solvothermal method. Octadecylamine as a soft template was used to direct the formation of porous structure. The as-prepared porous TiO(2) was characterized by low angle and wide angle X-ray diffraction, N(2) adsorption-desorption isotherms and BET surface area. The energy influence of ultrasound and heat and concentration of nitric acid for post extraction on formation of porous structure were investigated. The photocatalytic activities of TiO(2) were investigated by degrading toluene gas under UV light. The results revealed that proper energy facilitates the formation of porous structure and too low concentration of nitric acid cannot extract template from pores. The photocatalytic activities of TiO(2) with porous structure are higher than those of nonporous ones.     

锌卟啉敏化TiO2光催化剂的原位法制备及其光催化性能研究

以锌卟啉为敏化剂,采用溶剂热法原位合成了锌卟啉敏化TiO2复合光催化剂。利用XRD、SEM、UV-Vis DRS和TG-DTA对所得锌卟啉-TiO2复合光催化剂进行了表征和分析。分析结果表明,采用原位合成法能使锌卟啉原位负载于TiO2表面,且未改变TiO2的晶型和形貌;锌卟啉的存在使TiO2在可见光区域出现吸收峰,采用原位合成法制备的金属卟啉敏化TiO2光催化剂相对于溶剂回流法制备金属卟啉敏化TiO2光催化剂有更好的热稳定性和更好的催化降解亚甲基蓝性能。     

Controlled synthesis of anatase TiO2 octahedra with enhanced photocatalytic activity

Titanium dioxide (TiO₂) nanocrystals with specific exposed crystal facet have attracted considerable interest due to their promising applications in the fields of energy and environment. In this paper, we report on a simple solvothermal approach for the synthesis of anatase TiO₂ octahedra with high yield, using titanium(IV) sulfate and hydrazine hydrate as the starting materials. The formation mechanism of anatase TiO₂ octahedra is suggested. The samples were characterized with XRD, Raman, SEM, TEM, FTIR, XPS, and UV/vis techniques, and further tested as a candidate in photocatalysis to decompose methyl orange in aqueous solution at room temperature. The results show that SO₄²⁻ ions not only benefit the formation of octahedral nanocrystals, but also inhibit nitrogen doping into TiO₂ matrix. More importantly, it is found that the octahedral TiO₂ nanocrystals show enhanced photocatalytic activity compared to TiO₂ P25 and anatase TiO₂ counterparts.     

One-pot synthesis of oleic acid modified monodispersed mesoporous TiO2 nanospheres with enhanced visible light photocatalytic performance

Herein, we report a facile one-pot solvothermal method to prepare unique oleic acid (OA) modified monodispersed mesoporous TiO₂ nanospheres with carboxylate ligands from the oleic acid in the bidentate chelating linkage mode. The mesoporous OA-TiO₂ nanospheres have a very large specific surface of nearly 510?m²/g. The oleic acid cannot only act as a binding ligand to control the shape of mesoporous TiO₂ nanospheres, but also be benefit to enhance the visible-light absorption. The mesoporous OA-TiO₂ nanospheres exhibit an excellent photocatalytic performance in the degradation of Rhodamine B and phenol under the visible light irradiation and show almost no attenuation after four cycles.     

低温制备混晶TiO2纳米粒子及其光催化性能研究

通过低温液相合成混合晶型纳米TiO2颗粒,研究纳米TiO2颗粒的光催化活性与颗粒晶相组成之间关系.用XRD对其进行表征,并在紫外光下,以甲基橙光催化降解为模型反应,研究了不同晶相样品的光催化活性.结果表明:混合晶相中锐钛矿质量分数占69.8%、金红石质量分数占30.2%,TiO2光催化效用最好可达95.7%.     

Tuning and controlling photocatalytic performance of TiO2/kaolinite composite towards ciprofloxacin: Role of 0D/2D structural assembly

Lamellar kaolinite supported monodispersed TiO₂ was prepared through rational design and 0D/2D structural assembly, which showed significantly improved photocatalytic performance towards ciprofloxacin. After systematic evaluation, the pseudo-first-order kinetic constant rate of TiO₂/kaolinite composite can reach to 0.04549 min⁻¹, which was 6.90 and 1.81 times higher than that of pure TiO₂ and P25, respectively. The nano-TiO₂/kaolinite composite photocatalyst also displayed good reusability performance, only a slight decline occurred after four repeated experiments, which is beneficial for the large-scale application of photocatalysts. Various characterizations indicated that enhanced photocatalytic performance can be ascribed to the synergistic effect between natural kaolinite and the well distributed TiO₂, which enhanced the light absorption ability, assisted the dispersion of pure TiO₂, resulted in co-catalysis effect, improved the separation facilitation of photo-induced carriers and promoted the stronger adsorption capacity, etc. These merits effectively regulated the carriers’ lifetime and migration velocity of the photogenerated charge carriers. Considering the excellent properties of natural kaolinite (low cost, abundance, stability, etc.), our study provides a promising candidate for effective degradation of trace amounts of pharmaceutical and personal care product (PPCP) or contaminants with potential high-toxic risk.     

Combustion synthesized TiO2 for enhanced photocatalytic activity under the direct sunlight-optimization of titanylnitrate synthesis

Optimized synthesis of Ti-precursor ‘titanylnitrate’ for one step combustion synthesis of N- and C-doped TiO₂ catalysts were reported and characterized by using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), diffused reflectance UV–vis spectroscopy, N₂ adsorption and X-ray photoelectron spectroscopy (XPS). XRD confirmed the formation of TiO₂ anatase and nano-crystallite size which was further confirmed by TEM. UV-DRS confirmed the decrease in the band gap to less than 3.0 eV, which was assigned due to the presence of C and N in the framework of TiO₂ as confirmed by X-ray photoelectron spectroscopy. Degradation of methylene blue in aqueous solution under the direct sunlight was carried out and typical results indicated the better performance of the synthesized catalysts than Degussa P-25.     

Ionic liquid-assisted synthesis,structural characterization,and photocatalytic performance of CdS nanocrystals

With the assistance of the ionic liquid trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentylphosphinate), we have successfully synthesized short nanorods, quasi-nanospheres and faceted CdS nanoparticles via thermal decomposition of cadmium diethyldithiocarbamate complexes. It was shown that the shape, size and crystallinity of the products could be controlled through delicate regulation of the reaction temperature, monomer concentration, reaction time, and ionic liquid ratio. We found that higher temperature was beneficial to the good crystallinity, while the lower temperature and higher monomer concentration were in favor of anisotropic structures. The used ionic liquid contributed to the formation of hexagonal phase CdS nanocrystals, and its ratio played an important role in determining the ultimate morphology of products. The possible mechanism for the formation CdS nanocrystals was proposed. Furthermore, the as-prepared CdS samples demonstrated a highly photocatalytic activity in the degradation of methyl orange under visible light irradiation.     

Preparation of Ti3+/N-co-doped TiO2 by one-step hydrothermal synthesis method with high photocatalytic degradation performance under visible light

Journal of Materials Science: Materials in Electronics - Ti3+/N-co-doped TiO2 was successfully synthesized in situ by one-step hydrothermal method using tetrabutyl titanate (TBOT) as the titanium...     

Effects of Ti and TiO2 on Combustion Synthesis of (Ti,V)2AlC/Al2O3 Solid Solution Composites

(Ti,V)₂AlC/Al₂O₃ solid solution composites were prepared by solid state combustion simultaneously incorporating reduction reactions of V₂O₅ and TiO₂/V₂O₅ with aluminum. Two reaction systems composed of Ti–V₂O₅–Al–Al₄C₃ and TiO₂–V₂O₅–Al–Al₄C₃ powder mixtures were studied. Combustion exothermicity was enhanced by increasing V₂O₅ and Al, which not only caused an increase in the combustion temperature and reaction front velocity, but also facilitated evolution of the (Ti,V)₂AlC phase. Between two reaction systems, the Ti-containing samples were more energetic and produced (Ti_1–xV_x)₂AlC/Al₂O₃ composites with x = 0.2–0.8. The degree of element substitution was reduced for the samples adopting TiO₂, which yielded Al₂O₃-added (Ti_1–yV_y)₂AlC with y = 0.4–0.8.     

Controlled loading of MnS2 on porous TiO2 nanosheets for enhanced photocatalytic hydrogen evolution

Journal of Materials Science: Materials in Electronics - In this report, spherical nanoparticles/2D nanosheets based MnS2/TiO2 nanocomposites were prepared in different weight compositions which...     

Facile synthesis of pure BiFeO3 and Bi2Fe4O9 nanostructures with enhanced photocatalytic activity

Journal of Materials Science: Materials in Electronics - In the present work, pure BiFeO3 and pure Bi2Fe4O9 single phases were successfully synthesized by tailoring hydrothermal synthesis route....     

Controllable synthesis and photocatalytic activities of water-soluble TiO2 nanoparticles

Water-soluble anatase, mixed-phase (anatase and rutile) and rutile TiO₂ nanoparticles (NPs) or nanorods were synthesized under mild solution conditions using polyethylene glycol 400 (PEG 400) as a stabilizer and HCl as a phase controlling reagent. The photocatalytic properties of these NPs with different crystal phases were evaluated by photocatalytic degradation experiments of methyl orange (MO). As-prepared pure anatase TiO₂ NPs show a higher photocatalytic activity than other samples and commercial P25, which may be related to the high crystallinity, the pure anatase phase, small size and the enhanced absorbability associated with the existence of PEG 400 on the NP surface.     

Green synthesis of bi-component copper oxide composites and enhanced photocatalytic performance

A facile and green route was proposed for the synthesis of bi-component copper oxide composite without any templates and additives. The effects of D-(+)-glucose amount, reaction temperature, and reaction time on the morphology and constitution of the products were investigated by SEM, X-ray diffraction, and UV-vis DRS in detail. The results indicate that a series of Cu₂O–CuO bi-component copper oxide composites with various morphologies can be easily obtained. Structure characterisation and photocatalytic tests show that the bi-component Cu₂O–CuO composites exhibited better photodecolouration of methylene blue than those of the Cu₂O, CuO, and Cu–CuO compounds owing to the existence of the synergistic effect between the CuO and Cu₂O.     

Preparation of Bi2Ti2O7/TiO2 nanocomposites and their photocatalytic performance under visible light irradiation

To improve visible-light-driven photocatalytic activity of TiO₂, the octahedral Bi₂Ti₂O₇ nanoparticles have been successfully supported on TiO₂ nanotubes (Bi₂Ti₂O₇/TiO₂) for the first time by a simple hydrothermal method. The structure and electro-optical property of the Bi₂Ti₂O₇/TiO₂ were characterized in detail. The obtained Bi₂Ti₂O₇/TiO₂ exhibited a markedly enhanced photocatalytic activity and good stability for degradation of organic pollutants under visible light. The study presents a new way to synthesize Bi₂Ti₂O₇/TiO₂ using TiO₂ nanotubes as both supporter and reactant.