Modification of photocatalytic TiO2 thin films by electron beam irradiation

Noble metal-modified TiO₂ films were prepared by electron beam deposition of Pt, Pd, Au and Ag on the surface of TiO₂ films with diameters ranging from <1 nm to 500 nm. The morphology of the films was characterized by X-ray diffractometry (XRD), field emission scanning electron microscope (FMSEM) and transmission electron microscope (TEM). The photocatalytic capability of the films were tested and compared by degradation of methyl orange (MO) in aqueous solutions under both UV and visible light illumination.     

Pt助剂对N掺杂TiO2可见光光催化性能的影响

考察了Pt促进的N掺杂TiO2(Pt/N-TiO2)催化剂对光催化降解有机污染物性能的影响及其作用本质.采用X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射光谱、光电化学和荧光光谱等手段对催化剂进行了表征,并考察了样品在可见光下光催化降解甲基橙(MO)的反应性能.结果表明,Pt的存在并未明显改变N-TiO2的晶...     

Preparation and characterization of silver and indium vanadate co-doped TiO2 thin films as visible-light-activated photocatalyst

Novel visible-light-activated photocatalytic Ag/InVO₄-TiO₂ thin films were developed in this paper through a sol-gel method from the TiO₂ sol containing Ag and InVO₄. The photocatalytic activities of Ag/InVO₄-TiO₂ thin films were investigated based on the oxidation decomposition of methyl orange in aqueous solution. The Ag/InVO₄-TiO₂ thin films were characterized by X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy (UV-vis). The results revealed that the Ag/InVO₄-TiO₂ thin films extended the light absorption spectrum toward the visible region; the Ag and InVO₄ co-doped thin films significantly enhanced the methyl orange photodegradation under visible light irradiation. It has been confirmed that the Ag/InVO₄-TiO₂ thin films could be excited by visible light (E < 3.2 eV). The significant enhancement in the Ag/InVO₄-TiO₂ photo activity under visible light irradiation can be ascribed to the simultaneous effects of doped noble metal Ag by acting as electron traps and InVO₄ as narrow band gap sensitizer.     

Preparation of magnetically supported chromium and sulfur co-doped TiO2 and use for photocatalysis under visible light

Novel magnetic chromium and sulfur co-doped TiO₂ photocatalysts (M-Cr/S/TiO₂) have been prepared by a sol?Cgel process, using magnetic hollow fly ash microspheres as support material. The crystal phase of M-Cr/S/TiO₂ was characterized by X-ray diffraction, UV?Cvisible absorption spectroscopy, and transmission electron microscopy. The photocatalytic activity of the photocatalysts was examined by photodegradation of methyl orange in aqueous solution under visible light irradiation. The results showed that chromium and sulfur co-doped catalysts (Cr/S/TiO₂) containing 0.60?% (atomic ratio) chromium and 1.2?% (atomic ratio) sulfur calcined at 450?°C for 2?h had high catalytic efficiency under visible irradiation. It is worth mentioning that the floating M-Cr/S/TiO₂ catalyst had greater photocatalytic activity than Cr/S/TiO₂ powder. Therefore, M-Cr/S/TiO₂ is a promising, high-performing, visible-light-driven photocatalyst.     

Effect of nitrogen-doping temperature on the structure and photocatalytic activity of the B,N-doped TiO2

B,N-TiO₂ photocatalysts were synthesized by boron doping firstly and subsequently nitrogen doping in NH₃ at variable temperatures. The effects of the nitrogen doping temperature on the structure and photocatalytic activity of the B,N-codoped TiO₂ were investigated. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectrum (DRS), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated with photocatalytic degradation of methyl orange dye (MO) under visible light and UV-visible light irradiation. The results suggested that the boron and nitrogen can be incorporated into the TiO₂ lattice either interstitially or substitutionally or both, while the Ti-O-B-N structure plays a vital role in photocatalytic activity in visible light region. The optimal nitrogen doping temperature is 550 °C. Higher temperature may form many oxygen vacancies and Ti³⁺ species, resulting in the decrease of photocatalytic activity in visible light.     

Silver embedded C-TiO2 exhibits improved photocatalytic properties with potential application in waste water treatment

Non-metal element doping on photocatalysts demonstrates a wide range of disadvantages. Hence metal embedding on nanomaterials is considered to enhance photocatalytic efficiency. In this study, we employed silver nano particle embedding on C-TiO₂ photocatalyst to improve its phtotocatytic degradation efficiency of organic water pollutant such as methyl orange. Modified sol-gel methods based on self-assembly technique was used to prepare the nanoformulations. The synthesized nanoparticles were characterized by X-Ray diffraction (XRD), Fourier transforms infrared (FT-IR), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy, and photoluminescence spectra (PL). Compared to non-silver formulation (C-TiO₂), silver embedded nanomaterial (C-TiO₂/Ag) displayed an increased shift in the light absorption towards visible spectrum. A low photoluminescence (PL) intensity by 1 wt% C-TiO₂/Ag indicated improved photocatalytic efficiency. Further, higher degradation of organic dye methyl orange confirmed that 1 wt% C-TiO₂/Ag exhibited the best photodegradation rate over its non Ag embedded C-TiO₂. Embedding of silver on C-TiO₂ extends optical absorption edge of C-TiO₂ to more visible spectrum and inhibits electron-hole recombination resulting in enhanced photocatalytic activity. Photocatalytic degradation on methyl orange organic pollutant was considerably improved indicating its potential use in water treatment applications.     

Effect of Erbium on the Photocatalytic Activity of TiO2/Ag Nanocomposites under Visible Light Irradiation

Erbium co‐doped TiO₂/Ag catalysts are synthesized by using a simple, one‐step solvothermal method and characterized by X‐ray diffraction, field‐emission scanning electron microscopy, transmission electron microscopy, Raman analysis, X‐ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The catalysts exhibit anatase crystal structures with increased visible light absorption compared with pure TiO₂. Enhanced photocatalytic activity is observed with Er co‐doped TiO₂/Ag nanocomposites for Rhodamine B degradation under visible light irradiation. The photocatalytic activity of 1 % Er co‐doped TiO₂/Ag is much higher than that of TiO₂/Ag, TiO₂/Er, pure TiO₂, and commercial Degussa P25. The kinetics of the degradation process are studied and the pseudo‐first‐order rate constant (k) and half‐life time (t_1/2) of the reaction are calculated. The enhanced activity might be accredited to the efficient separation of electron–hole pairs by silver and higher visible light absorption of TiO₂ induced by Er.     

Photocatalytic applications of Au-deposited on TiO2 nanocomposite catalyst in dye degradation via photoreduction

The photocatalytic activity of gold deposited on Degussa P25 titanium dioxide (Au-DP25) in the photodegradation of methyl orange (MO) was investigated. The as-prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS) techniques. The obtained results show that the gold (Au⁰) deposited TiO₂ exhibited visible light plasmon absorption band. The degradation experiment j reveals that the catalytic activity of Au-DP25 in the degradation of MO is higher than that of commercially available Degussa P25 TiO₂ (DP25) samples. In addition, the photocatalytic ability of composite Au-DP25 was hardly decreased after a five-cycle for MO degradation. The kinetics of the MO degradation fitted well the Langmuir-Hinshelwood model.     

Characterization of Visible Light Response N-F Codoped TiO2 Photocatalyst Prepared by Acid Catalyzed Hydrolysis

N-F codoped TiO₂ (TONF) photocatalysts were prepared using acid catalyzed hydrolysis method from mixed aqueous solution of TiCl₄ and NH₄F. The photocatalytic activity of the TONF was evaluated through the degradation of phenol under both visible and UV light irradiation. X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), scanning electron microscope (SEM), and N₂ adsorption isotherm were used to characterize the obtained powders. The results showed that N-F codoped TiO₂ exhibited significant improvement of visible light catalytic activity. N-F codoping could improve dispersion of TiO₂, inhibit particle size agglomeration, and retard phase transformation. Doped N could extend the light response of TiO₂ to visible light region. In addition, narrower band gap formed by F-doping was beneficial to the high visible light photocatalytic activity.     

Ag@AgI等离子体负载TiO2酸蚀纳米带的制备及可见光光催化性能的研究

采用沉积-沉淀法将AgI分散到TiO2酸蚀纳米带上,然后通过光照进而分解出Ag颗粒,最终获得了Ag@AgI等离子体负载的TiO2酸蚀纳米带(AIST)。利用UV-Vis吸收光谱、XRD、SEM对产物进行表征,并研究了可见光下对甲基橙(MO)的光催化降解性能。结果表明,纳米带酸蚀后利于AgI的沉积,Ag的表面等离子体共振效应可以增强催化剂对于可见光的吸收,使可见光下AIST的光催化降解性能显著提高。     

Microemulsion Synthesis of Nanosized TiO2 Particles Doping with Rare-Earth and their Photocatalytic Activity

Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO₂ and Ce-TiO₂ particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO₂ with doping TiO₂, the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.     

Photocatalytic activity of Au/TiO<Subscript>2</Subscript> nanocomposite for azo-dyes degradation

The structural properties of Au/TiO₂ catalyst were studied by X-ray diffraction, UV-visible diffuse reflectance, photoluminescene, scanning transmission and electron microscope, and temperature programmed reduction. The photocatalytic activity of the catalysts was evaluated for the degradation of various azo-dyes such as methylene blue, methyl orange, reactive blue-4, and eosin-B under solar irradiation. It was found that TiO₂ catalyst modified with gold exhibits higher percentage of degradation compared to starting TiO₂. For example, TiO₂ showed 35% of methyl orange degradation whereas gold modified TiO₂ possessed 82%. Effect of different parameters such as pH and dye concentration has been evaluated and the photocatalytic activity was correlated with physico-chemical properties. The dye degradation rate followed first order kinetics.     

Preparation of high‐activity AgBr/Ag3PO4 photocatalyst based on hexadecyltrimethylammonium bromide and mechanism of photocatalytic enhancement

A high‐activity AgBr/Ag₃PO₄ heterojunction photocatalyst was synthesized based on hexadecyltrimethylammonium bromide. Its microspheres were characterized using X‐ray diffractometry, transmission electron microscopy and ultraviolet–visible diffuse reflectance spectroscopy. The new photocatalyst with high photocatalytic activity exceptionally outperforms pure Ag₃PO₄ and AgBr in methyl orange degradation. The enhancement of photocatalytic activity is attributed to the efficient separation of electron–hole pairs. In this photocatalytic reaction, h⁺ and ^?O^2? are the main reactive species that induce visible‐light‐driven degradation.     

Characterization of Pd/TiO2 embedded in multi-walled carbon nanotube catalyst with a high photocatalytic activity

Pd particles loading on TiO₂-embedded multi-walled carbon nanotubes (MWCNTs), MWCNTs, and TiO₂ particles were prepared via an impregnation method with palladium(II) chlorate solution followed by heat treatment at high temperature. To characterize the catalysts, BET surface area, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were employed. The prepared catalysts were tested in degradation of methyl orange under visible light. Pd/TiO₂-MWCNTs catalyst demonstrates the highest photocatalytic activity, and the phase transformation from PdO to Pd0 phase takes place at heat treatment of embedded TiO₂. The nanoparticles size of TiO₂ can be decreased by introduction of MWCNTs species. Combining structural characterization with kinetic study results we could conclude that the superior catalytic performance could arise due to the Pd/TiO₂-MWCNTs catalyst’s structure.     

具有高可见光催化活性的Ti3+和碳共掺杂改性的TiO2光催化剂

以乙醇为碳源,采用操作简单的真空活化法一步实现对TiO₂的Ti³⁺与C的共掺杂改性,TiO₂用X衍线衍射、紫外-可见光谱、顺磁共振、X射线光电子能谱和红外光谱等手段表征了催化剂的结构、组成、光学性质. 结果表明, 经Ti³⁺与C共掺杂改性后的催化剂表现出高的可见光降解甲基橙活性. 复合在催化剂表面的石墨可以增强催化剂对可见光的响应范围,而Ti³⁺与氧缺陷形成的掺杂能级则可以提高光生电子的迁移效率. 实验表明,两者之间的协同作用促进了其可见光催化活性的提高.     

Preparation and characterization of ZnTiO<Subscript>3</Subscript>–TiO<Subscript>2</Subscript>/pillared montmorillonite composite catalyst for enhanced photocatalytic activity

ZnTiO₃–TiO₂/organic pillared montmorillonite (pMt) composite catalyst was successfully prepared in this paper by immobilizing ZnTiO₃–TiO₂ onto pMt. The composition and texture of the prepared composite catalyst were characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, energy dispersive spectrometry, ultraviolet–visible light (UV–Vis) diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activity was tested via photocatalytic degradation of methyl blue (MB) under both visible irradiation and UV light. The results indicated that the ZnTiO₃–TiO₂/pMt composite catalyst had an apparent absorption at the area of visible irradiation, and exhibited a higher efficiency of photocatalytic degredation of MB under visible irradiation. This was due to the heterostructure of ZnTiO₃–TiO₂, and the mesoporous structure and specific surface area of the ZnTiO₃–TiO₂/pMt composite. In addition, the results of the radical scavenging experiments showed that the holes and superoxide radicals are responsible for the degradation of MB under visible irradiation.     

Synthesis and characterization of ZnO-doped cupric oxides and evaluation of their photocatalytic performance under visible light

ZnO–CuO binary oxide photocatalysts were synthesized by the liquid phase coprecipitation method. The catalysts were characterized by X-ray diffraction, transmission electron microscopy and UV–vis spectroscopy. The photocatalytic activity of the ZnO–CuO nanocomposites was estimated on the basis of decoloration of methyl orange dye under visible light. The effects of parameters such as calcining temperature, amount of catalyst and pH on the photocatalytic degradation efficiency of methyl orange solutions were investigated in detail. The maximum photocatalytic activity was obtained on ZnO–CuO nanocomposites with a calcining temperature of 350 °C, using a catalyst amount of 0.056 g/L and a pH of 7.5. The visible light-driven capability of ZnO–CuO nanocomposites is much better than that of commercially available TiO₂ photocatalysts under comparable conditions.     

Template‐free Fabrication of Hierarchical Macro‐/mesoporous N‐doped TiO2/graphene Oxide Composites with Enhanced Visible‐light Photocatalytic Activity

Hierarchical macro‐/mesoporous N‐doped TiO₂/graphene oxide (N‐TiO₂/GO) composites were prepared without using templates by the simple dropwise addition mixed solution of tetrabutyl titanate and ethanol containg graphene oxide (GO) to the ammonia solution, and then calcined at 350 °C. The as‐prepared samples were characterized by scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller (BET) surface area, X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐Vis absorption spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under visible‐light irradiation. The results show that N‐TiO₂/GO composites exhibited enhanced photocatalytic activity. GO content exhibited an obvious influence on photocatalytic performance, and the optimal GO addition content was 1 wt%. The enhanced photocatalytic activity could be attributed to the synergetic effects of three factors including the improved visible light absorption, the hierarchical macro‐mesoporous structure, and the efficient charge separation by GO.     

ZnFe2O4/Ag/TiO2复合材料的制备及其光催化性能

以硝酸银、钛酸四丁酯、无水氯化锌、六水氯化铁为原料,采用溶胶-凝胶法与溶剂热相结合的方法制备了ZnFe₂O₄/Ag/TiO₂复合材料,通过扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、X射线光电子能谱仪、振动样品磁强计、紫外可见分光光度计对样品进行表征及测试。结果表明：ZnFe₂O₄/Ag/TiO₂-10具有最佳的光催化效果,在紫外和可见光下对染料的降解率都能达到90%以上,具有优异的紫外可见光光催化活性。ZnFe₂O₄/Ag/TiO₂具有独特的磁性,能在外部磁场作用下进行回收利用,这使其在实际应用中成为可能。通过磁分离技术重复回收利用5次后仍然保持优良的光催化性能,说明ZnFe₂O₄/Ag/TiO₂-10具有优异的磁性及较高的光催化循环稳定性。     

ZnFe2O4/Ag/TiO2复合材料的制备及其光催化性能

以硝酸银、钛酸四丁酯、无水氯化锌、六水氯化铁为原料,采用溶胶-凝胶法与溶剂热相结合的方法制备了ZnFe₂O₄/Ag/TiO₂复合材料,通过扫描电子显微镜、能谱分析仪、X射线粉末衍射仪、X射线光电子能谱仪、振动样品磁强计、紫外可见分光光度计对样品进行表征及测试。结果表明： ZnFe₂O₄/Ag/TiO₂-10具有最佳的光催化效果,在紫外和可见光下对染料的降解率都能达到90%以上,具有优异的紫外可见光光催化活性。ZnFe₂O₄/Ag/TiO₂具有独特的磁性,能在外部磁场作用下进行回收利用,这使其在实际应用中成为可能。通过磁分离技术重复回收利用5次后仍然保持优良的光催化性能,说明ZnFe₂O₄/Ag/TiO₂-10具有优异的磁性及较高的光催化循环稳定性。