Preparation and Photocatalytic Activity of Mesoporous TiO2 Photocatalyst Co‐doped with Fe and H3PW12O40

The mesoporous titanium dioxide (MTiO₂) photocatalysts co‐doped with Fe and H₃PW₁₂O₄₀ were synthesized by template method using tetrabutyl titanate (Ti(OC₄H₉)₄), Fe(NO₃)k₃9H₂Oand H₃PW₁₂O₄₀ as precursors and Pluronic P123 as template. The as‐prepared photocatalyst was characterized by N₂ adsorption‐desorption measurements, X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐vis adsorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl blue (MB) (50 mg/L) in an aqueous solution. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m²/g. The results of MB photodecomposition showed that co‐doped mesoporous TiO₂ exhibited higher photocatalytic activities than un‐doped, single‐doped mesoporous TiO₂ under UV and visible light irradiation. It was shown that the co‐doped MTiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The synergistic effect of Fe and H₃PW₁₂O₄₀ co‐doping played an important role in improving the photocatalytic activity.     

Room Temperature Synthesis and Photocatalytic Activity of Magnetically Recoverable Fe3O4/BiOCl Nanocomposite Photocatalysts

Magnetically recoverable Fe₃O₄/BiOCl nanocomposite photocatalysts were fabricated by a simple chemical coprecipitation method at room temperature. The amount of Fe₃O₄ incorporated into BiOCl was varied from 0 to 20 wt%. The as-synthesized samples were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, UV–Vis diffuse reflectance spectroscopy, and vibrating sample magnetometer. The obtained results show that the as-synthesized samples mainly contain both crystalline phases (Fe₃O₄ and BiOCl) and are composed of flower-like nanostructures. Compared to UV light-responsive BiOCl, all the nanocomposite photocatalysts show a strong light absorbance in the range of 250–800 nm, demonstrating that the Fe₃O₄/BiOCl nanocomposites can respond to visible as well as UV light. Moreover, visible light absorbance was increased with the increase in the Fe₃O₄ amount in the composite. The photocatalytic activity of nanocomposite photocatalysts was evaluated by the photodegradation of Rhodamine B (RhB) over the samples under visible light irradiation. The 10 wt% Fe₃O₄/BiOCl nanocomposite photocatalyst shows the highest photocatalytic efficiency among the samples. The Fe₃O₄/BiOCl nanocomposite photocatalyst was stable under visible light irradiation to efficiently degrade RhB molecules after five cycles and could be easily recovered with a magnet after each cycle.     

具有分级多孔结构和光催化性质的核-壳纳米球(HP-Fe2O3@TiO2)

通过溶剂热和溶胶-凝胶涂层法, 设计并制备了具有分级多孔结构和光催化性质的核-壳纳米球(HP-Fe₂O₃@TiO₂). 透射电子显微镜(TEM)照片证明所得HP-Fe₂O₃@TiO₂样品具备分级多孔结构, 这是因为HP-Fe₂O₃@TiO₂的内核-Fe₂O₃具有大孔空隙, 同时外壳-TiO₂具有介孔空隙. 此外, 通过X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)以及氮气吸附-脱附曲线深入研究了HP-Fe₂O₃@TiO₂的结构及其性质. 分别在可见及紫外光照下, 研究了样品在H₂O₂体系下的光催化降解亚甲基蓝(MB)的性质. 所观察到的HP-Fe₂O₃@TiO₂纳米球的光催化性能, 可归因于核-壳结构的协同作用, 这进一步表明, TiO₂外壳对α-Fe₂O₃的光催化活性有重要影响作用. 在可见光照射下, HP-Fe₂O₃@TiO₂ (1 mL Ti(OC₄H₉)₄ (TBT))具有较优异的光催化活性. 同时, HP-Fe₂O₃@TiO₂ (4mL TBT)具备优异的单分散形貌, 并在紫外光照射下, 表现出最优的光催化活性.     

Evaluating the efficiency of the GO‐Fe3O4/TiO2 mesoporous photocatalyst for degradation of chlorpyrifos pesticide under visible light irradiation

In this work, the photocatalytic activity of the synthesized graphene oxide (GO)‐Fe₃O₄/TiO₂ mesoporous photocatalysts was evaluated using chlorpyrifos (CP) as a contaminant. The nano‐photocatalyst was characterized by X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, and specific surface area by the Brunauer–Emmett–Teller method. Using visible light, the GO‐Fe₃O₄/TiO₂ mesoporous photocatalyst was investigated on the degradation of CP pesticide. The GO‐Fe₃O₄/TiO₂ photocatalyst displayed a good photocatalytic activity, which was achieving 97% of CP degradation after 60 min. Finally, experiments were performed to evaluate GO‐Fe₃O₄/TiO₂ mesoporous nanocatalyst activity on repeated applications; after several uses, its photocatalytic activity was retained, which indicated stability.     

Novel Bi2WO6‐coupled Fe3O4 Magnetic Photocatalysts: Preparation,Characterization and Photodegradation of Tetracycline Hydrochloride

Novel Bi₂WO₆‐coupled Fe₃O₄ magnetic photocatalysts with excellent and stable photocatalytic activity for degrading tetracycline hydrochloride and RhB were successfully synthesized via a facile solvothermal route. Through the characterization of the as‐prepared magnetic photocatalysts by X‐ray diffractometry, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra, it was found that the as‐prepared magnetic photocatalysts were synthesized by the coupling of Bi₂WO₆ and Fe₃O₄, and introduction of appropriated Fe₃O₄ can improve nanospheres morphology and visible‐light response. Among them, BFe2 (0.16% Fe₃O₄) exhibited the best photocatalytic activity for degradation of tetracycline hydrochloride (TCH), reaching 81.53% after 90 min. Meanwhile, the as‐prepared magnetic photocatalysts showed great separation and recycle property. Moreover, the results of electrochemical impedance spectroscopy demonstrated that the well conductivity of Fe₃O₄ can promote photogenerated charge carriers transfer and inhibit recombination of electron–hole pairs, so that Bi₂WO₆/Fe₃O₄ exhibited enhanced photocatalytic activity on degradation of TCH and RhB. Hence, this work provides a principle method to synthesize Bi₂WO₆/Fe₃O₄ with excellent photocatalytic performance for actual application, in addition, it showed that introduction of Fe₃O₄ not only can provide magnetism, but also can enhance photocatalytic activity of Bi₂WO₆/Fe₃O₄ magnetic photocatalysts.     

Photocatalytic Activity of Fe and Ce Co‐doped Mesoporous TiO2 Catalyst under UV and Visible Light

The catalysts of un‐doped, single‐doped and co‐doped mesoporous titanium dioxide (MTiO₂) were prepared by a template method with tetrabutyltitanate (Ti(OC₄H₉)₄) as a Ti source material and Pluronic P123 as a template. The photo‐absorbance of the obtained catalysts was measured by UV‐vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange (MO) (50 mg/L) in an aqueous solution. It was shown that the co‐doped MTiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The effect of Fe and Ce co‐dopants on the material properties was investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and N₂ adsorption‐desorption isotherm measurement. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m²/g. The photocatalytic activity of MTiO₂ co‐doped with Fe and Ce was markedly improved due to the synergistic actions of the two dopants.     

Photodegradation of Direct Blue-199 in carpet industry wastewater using iron-doped TiO2 nanoparticles and regenerated photocatalyst

Fe-doped TiO_2, Ti_1–xFe_xO₂ (x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10), photocatalysts have been successfully synthesized via citric acid–assisted autocombustion method. The synthesized photocatalysts were characterized using different characterization techniques, such as X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), and x-ray photoelectron spectroscopy (XPS). The XRD diffraction patterns revealed that synthesized photocatalysts have the anatase phase of TiO₂. The DRS analysis indicates a slight increment in absorbance in the visible light region by the Fe doping in TiO₂. The FT-IR spectra reveal the various stretching and bending vibrational bands of the Ti–O lattice. The XPS spectra confirm the presence of elements titanium, oxygen, and iron in the synthesized samples and determine binding energy of elements. TEM analysis shows the shape of the synthesized photocatalyst, and it was used to calculate the average particle sizes of undoped and Fe-doped TiO₂ (Ti_0.96Fe_0.04O₂) photocatalysts using a histogram. The photocatalytic activities of synthesized photocatalysts were determined by photodegradation of dye (Direct Blue 199), contaminating carpet industry wastewater in the photochemical reactor and open pan reactor. The maximum photodegradation activity was shown by the Ti_0.96Fe_0.04O₂ photocatalyst among all the synthesized undoped and Fe-doped photocatalysts. The synthesized photocatalyst (Ti_0.96Fe_0.04O₂) had better photocatalytic activity when compared to both, undoped TiO₂ and Aeroxide (Degussa) P-25. The used Fe-doped TiO₂ photocatalyst (Ti_0.96Fe_0.04O₂) was regenerated five times and investigated for its photocatalytic activity.     

Sensitization of wide band gap photocatalysts to visible light by molten CuCl treatment

Cu(i)-substituted metal oxide photocatalysts were prepared using molten CuCl treatment of wide band gap photocatalysts. The Cu(i)-substituted metal oxide photocatalysts possessed a new absorption band in the visible light region and showed photocatalytic activity for hydrogen evolution from an aqueous solution containing sulfur sacrificial reagents under visible light irradiation. Notably, the Cu(i)–K₂La₂Ti₃O₁₀ and Cu(i)–NaTaO₃ photocatalysts showed relatively high activities for hydrogen evolution and gave apparent quantum yields of 0.18% at 420 nm. These photocatalysts responded up to 620 nm. Thus, Cu(i)-substitution using a molten CuCl treatment was an effective strategy for sensitizing a metal oxide photocatalyst with a wide band gap to visible light.     

Synthesis of Fe<Superscript>3+</Superscript> doped ordered mesoporous TiO<Subscript>2</Subscript> with enhanced visible light photocatalytic activity and highly crystallized anatase wall

Fe³⁺ doped mesoporous TiO₂ with ordered mesoporous structure were successfully prepared by the solvent evaporation-induced self-assembly process using P123 as soft template. The properties and structure of Fe³⁺ doped mesoporous TiO₂ were characterized by means of XRD, EPR, BET, TEM, and UV–vis absorption spectra. The characteristic results clearly show that the amount of Fe³⁺ dopant affects the mesoporous structure as well as the visible light absorption of the catalysts. The photocatalytic activity of the prepared mesoporous TiO₂ was evaluated from an analysis of the photodegradation of methyl orange under visible light irradiation. The results indicate that the sample of 0.50%Fe–MTiO₂ exhibits the highest visible light photocatalytic activity compared with other catalysts.     

一锅法制备Co3O4/g-C3N4复合光催化剂及其光催化性能

以三聚氰胺和六水合氯化钴为原料,一锅法制备Co_3O_4负载的多孔石墨相氮化碳(Co_3O_4/g-C_3N_4)复合光催化材料。采用X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、光致发光光谱(PL)等手段对其结构和光学特性进行表征。以盐酸四环素(TC)为目标污染物,评价了不同负载量Co_3O_4/g-C_3N_4复合光催化剂的可见光催化性能。结果表明,所制备的Co_3O_4/g-C_3N_4复合光催化剂为多孔结构,其比表面积较大,并在可见光区域具有显著的吸收。利用原位生成的Co_3O_4纳米粒子在氮化碳表面形成异质结构,可有效转移光生载流子,降低光生电子-空穴的再结合率,从而提高光催化活性。并且存在最佳Co_3O_4复合量,当六水合氯化钴加入量为三聚氰胺的8%(w/w)时,所制备的复合光催化剂CoCN-8具有最佳的光催化性能。在可见光的照射下,60 min内可降解85%的TC,而同样条件下,纯g-C_3N_4仅降解23%的TC。     

In-situ construction of amorphous/crystalline contact Bi2S3/Bi4O7 heterostructures for enhanced visible-light photocatalysis

Constructing a heterojunction photocatalyst is a significant method to enhance photocatalytic activity because it can promote the separation of photogenerated carriers. Herein, amorphous/crystalline contact Bi₂S₃/Bi₄O₇ heterostructure was successfully synthesized by in-situ sulfidation of Bi₄O₇. The amorphous Bi₂S₃ is diffused on the surface of Bi₄O₇ rod, enhancing the visible light response and improving the transport of photogenerated carriers. Various characterizations confirm that the rapid separation of photogenerated carriers leads to increased photocatalytic performance. The optimized Bi₂S₃/Bi₄O₇ heterostructure photocatalyst (BiS-0.15) exhibits the highest Cr(VI) reduction (0.01350 min⁻¹) and RhB oxidation (0.08011 min⁻¹) activity, which is much higher than that of pure Bi₄O₇ and Bi₂S₃/Bi₄O₇ mixture under visible light irradiation. This work provides new insights into the construction of efficient novel photocatalysts.     

Hydrothermal Synthesis of g‐C3N4/NiFe2O4 Nanocomposite and Its Enhanced Photocatalytic Activity

Herein, for the first time, a direct Z‐scheme g‐C₃N₄/NiFe₂O₄ nanocomposite photocatalyst was prepared using facile one‐pot hydrothermal method and characterized using XRD, FT‐IR, DRS, PL, SEM, EDS, TEM, HRTEM, XPS, BET and VSM characterized techniques. The result reveals that the NiFe₂O₄ nanoparticles are loaded on the g‐C₃N₄ sheets successfully. The photocatalytic activities of the as‐prepared photocatalysts were evaluated for the degradation of methyl orange (MO) under visible light irradiation. It was shown that the photocatalytic activity of the g‐C₃N₄/NiFe₂O₄ nanocomposite is about 4.4 and 3 times higher than those of the pristine NiFe₂O₄ and g‐C₃N₄ respectively. The enhanced photocatalytic activity could be ascribed to the formation of g‐C₃N₄/NiFe₂O₄ direct Z‐scheme photocatalyst, which results in efficient space separation of photogenerated charge carriers. More importantly, the as‐prepared Z‐scheme photocatalyst can be recoverable easily from the solution by an external magnetic field and it shows almost the same activity for three consecutive cycles. Considering the simplicity of preparation method, this work will provide new insights into the design of high‐performance magnetic Z‐scheme photocatalysts for organic contaminate removal.     

Elaboration of nano titania-magnetic reduced graphene oxide for degradation of tartrazine dye in aqueous solution

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO₂) and magnetite (Fe₃O₄) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO₂/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO₂ nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO₂ for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).     

One-pot sequential synthesis of magnetically separable Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/AgCl photocatalysts with enhanced activity and stability

Magnetically separable Fe₃O₄/AgCl photocatalysts were prepared by a one-pot sequential method. A series of techniques proved the hybrid structure of Fe₃O₄/AgCl composites. Fe₃O₄/AgCl composites had a much higher photocatalytic activity toward Rhodamine B (RhB) degradation than pure AgCl under the simulated solar light irradiation. The existence of metal Ag resulted in high photocatalytic activity of Fe₃O₄/AgCl, which was related with the amount of metallic Ag. The scavenging experiments showed that the degradation reaction most probably was initiated by the photoinduced single-electron transfer, and the generation of superoxide anion (O ₂ ^-· ) played a significant role. The composite photocatalysts could be recycled by applying an external magnetic field, and the reused composites maintained their original photocatalytic activity. Fe₃O₄/AgCl composites were highly efficient, magnetically separable, and recoverable. This proves their potential applications in the photodegradation of organic pollutants.     

Photocatalyst Materials for Water Splitting

Various photocatalyst materials developed by the group of the present author are described. Alkali and alkaline earth tantalates have arisen as a new group of photocatalyst materials for splitting of water into H₂ and O₂ under ultraviolet irradiation. They showed activities even without co-catalysts such as Pt, being different from titanate photocatalysts. When NiO co-catalysts were loaded on the tantalate photocatalysts, the photocatalytic activities were markedly increased. Among the tantalates, NiO/NaTaO₃ doped with La showed the highest activity. BiVO₄, AgNO₃, and TiO₂ co-doped with Cr and Sb photocatalysts showed high activities for O₂ evolution in the presence of a sacrificial reagent (Ag⁺) under visible light irradiation ( > 420 nm). Pt/SrTiO₃ co-doped with Cr and Sb or Ta, Pt/NaInS₂, and Pt/AgInZn₇S₉ photocatalysts showed high activities for H₂ evolution from aqueous solutions containing reducing reagents under visible light irradiation. Furthermore, Cu- or Ni-doped ZnS photocatalysts showed H₂ evolution activities even without co-catalysts such as Pt.     

In situ preparation of Bi2O3/(BiO)2CO3 composite photocatalyst with enhanced visible-light photocatalytic activity

A Bi₂O₃/(BiO)₂CO₃ (BO/BOC) composite photocatalyst was in situ prepared via calcinating (BiO)₂CO₃. The as-prepared Bi₂O₃/(BiO)₂CO₃ composites displayed enhanced photocatalytic activity for the degradation of RhB under visible light. The structure–activity relationship between catalyst structure and properties was investigated by SEM, XRD, XPS, FTIR, BET, DRS and photoelectrochemical tests. Apart from the increased absorption of visible light, the accelerated charge separation and transfer was achieved via the intimate contact and matched band structure between Bi₂O₃ and (BiO)₂CO₃. The formation of heterogeneous structures could promote the production of reactive oxygen species (·O₂^?) and eventually improve the photocatalytic performance for the removal of organic contaminants. This heating treatment strategy might be extended for improving light absorbance and charge carriers separation for other UV-based photocatalysts.

     

Fe2BiTaO7纳米催化剂的组织结构及光催化性能

用固相反应合成法合成了光催化剂Fe2BiTaO7,通过XRD、SEM、TEM、紫外-可见漫反射等表征方法对其组织结构及光催化性能进行了研究。结果表明Fe2BiTaO7为立方晶系烧绿石结构,空间群为Fd3m,禁带宽度为1.72 e V。通过比较Fe2BiTaO7、P25TiO2、掺氮Ti O2和Bi2In Ta O7的可见光光催化降解罗丹明B,发现Fe2BiTaO7降解效果及催化活性均高于其它催化剂,并且Fe2BiTaO7降解罗丹明B效率是掺氮二氧化钛的1.5倍。Fe2BiTaO7降解罗丹明B的曲线符合一级动力学,一级动力学常数为0.022 93 min-1。研究了罗丹明B可能的降解路径和Fe2BiTaO7在可见光下降解苯酚的效果。Fe2BiTaO7(可见光)光催化剂系统适用于纺织工业废水处理。     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载CdMoO₄光催化剂。运用X射线粉末衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱（UV-Vis DRS）和X射线光电子能谱（XPS）等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对CdMoO₄紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与CdMoO₄相比,Ag/CdMoO₄具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O₂^-·和·OH是光催化降解过程的主要活性物种。     

Stepwise construction of Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and magnetic separability for efficient visible-light photocatalysis

Solid photocatalysts with high specific surface area,superior photoactivity and ease of recycling are highly desired in chemical process,water treatment and so on.In this study,a facile stepwise sol-gel coating approach was utilized to synthesize Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and convenient magnetic separability(denoted as Fe_3 O_4@-SiO_2@Pt/mTiO_(2-x)).These photocatalysts consist of magnetic Fe_3 O4 cores,nonporous insulating SiO_2 middle layer and mesoporous anatase TiO_(2-x) shell decorated by Pt nanoparticles(～3.5 nm) through wet impregnation and H_2 reduction.As a result of high activity of oxygen-deficiency of black TiO_(2-x) by H_2 reduction and efficient inhibition of electron-hole recombination by Pt nanoparticles,the rationally designed core-shell Fe_3 O_4@SiO_2@Pt/mTiO_(2-x) photocatalysts exhibit superior photocatalytic performance in rhodamine B(RhB) degradation under visible light irradiation,with more than 98% of RhB degraded within 50 min.These core-shell structured photocatalysts show excellent recyclability under the assistance of magnetic separation with well-retained photocatalytic performance even after running five cycles.This stepwise synthesis method paves the way for the rational design of a high-efficiency recyclable heterogeneous catalyst,including photocatalysts,for various applications.     

掺杂Fe2O3对吸附相反应技术制备TiO2的形貌和光催化性能的影响

利用吸附相反应技术制备得到了掺杂不同浓度的Fe₂O₃的TiO₂复合光催化剂。通过透射电子显微镜(TEM)、紫外可见光谱和X射线衍射(XRD)研究不同掺杂浓度对TiO₂形貌和结晶过程的影响,并利用3种波长光源下的甲基橙光降解实验考评了各个复合光催化剂的催化活性。结果表明,掺杂后复合光催化剂中Fe₂O₃分散性较好较均匀。在TiO₂紫外可见吸收光谱中由于Fe₂O₃的掺杂而出现了红移,而且随着掺杂浓度增加红移越来越明显,复合光催化剂的禁带宽度也越来越小。在焙烧过程中无定形Fe₂O₃或Fe³⁺进入了TiO₂的晶格结构,从而抑制了TiO₂的结晶过程。半导体禁带宽度的减少以及TiO₂结晶过程的抑制作用,都导致紫外光下复合光催化剂催化活性的降低。但Fe₂O₃的掺杂也使得复合光催化剂在可见光区出现了一定的光催化活性。