Fabrication of CdS and CuWO4 modified TiO2 nanoparticles and its photocatalytic activity under visible light irradiation

CdS and CuWO₄ modified TiO₂ nanoparticles (CdS–CuWO₄-TiO₂) were prepared by the chemical impregnation method. The as-prepared nanoparticles were characterized using UV–visible-diffuse reflectance spectroscopy (UV–vis-DRS), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and B.E.T. surface area analysis techniques. The photocatalytic activity was evaluated based on the degradation of a dye (eosin-Y) and inactivation of a bacterium (Pseudomonas aeruginosa). The results revealed that CdS–CuWO₄-TiO₂ showed high photocatalytic activity over CdS-TiO₂, CuWO₄-TiO₂ and TiO₂. Moreover the reusability and stability of the photocatalyst for the degradation of eosin-Y was also studied.     

A unique Cu2O/TiO2 nanocomposite with enhanced photocatalytic performance under visible light irradiation

A unique Cu₂O/TiO₂ nanocomposite with high photocatalytic activity was synthesized via a two-step chemical solution method and used for the photocatalytic degradation of organic dye. The structure, morphology, composition, optical and photocatalytic properties of the as-prepared samples were investigated in detail. The results suggested that the Cu₂O/TiO₂ nanocomposite is composed of hierarchical TiO₂ hollow microstructure coated by a great many Cu₂O nanoparticles. The photocatalytic performance of Cu₂O/TiO₂ nanocomposite was evaluated by the photodegradation of methylene blue (MB) under visible light, and compared with those of the pure TiO₂ and Cu₂O photocatalysts synthesized by the identical synthetic route. Within 120 min of reaction time, nearly 100% decolorization efficiency of MB was achieved by Cu₂O/TiO₂ photocatalyst, which is much higher than that of pure TiO₂ (26%) or Cu₂O (32%). The outstanding photocatalytic efficiency was mainly ascribed to the unique architecture, the extended photoresponse range and efficient separation of the electron-hole pairs in the Cu₂O/TiO₂ heterojunction. In addition, the Cu₂O/TiO₂ nanocomposite also retains good cycling stability in the photodegradation of MB.     

Ag2O/BaFe12O19 nanoheterojunctions for rapid photoelimination of atrazine herbicide in water under visible light

The progress in ceramic oxide photocatalysts is a central issue in the environmental remediation of herbicides in water. Atrazine (ATZ) is a potential herbicide applied in different cultivation and food-based manufacturing processes. This paper introduces a solution-based route to synthesize barium hexaferrite (BhF) nanostructures. Formerly, trace amounts (0.4–2.0 wt%) of silver oxide (Ag₂O) were deposited on BhF to produce Ag₂O/BhF nanoheterojunctions. Characterization of the produced materials significantly introduced Ag₂O to the BhF photoactivity without altering the main structural or surface properties. The 1.2 wt%-added Ag₂O/BhF favored light harvesting and reduced the bandgap to 1.56 eV. The dose optimization (0.8 L^–1) of Ag₂O/BhF exhibited rapid photoelimination of ATZ in 40 min with exceptional stability after five cycles. The photocatalytic competence enhancement of Ag₂O/BhF is regarded as the efficient separation of photogenerated carriers by p-n nanojunction construction. This work presents the application of nanoheterojunction oxides for eco-friendly herbicide remediation.     

Fullerene modification CdSe/TiO2 and modification of photocatalytic activity under visible light

CdSe, CdSe-TiO₂, and CdSe-C₆₀/TiO₂ composites were prepared using sol–gel method, and their photocatalytic activity was evaluated by measuring the degradation of rhodamine B solutions under visible light. The surface area, surface structure, crystal phase, and elemental identification of these composites were characterized by nitrogen adsorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and UV-visible (vis) absorption spectrophotometry. XRD showed that the CdSe-C₆₀/TiO₂ composite contained a typical single and clear anatase phase. SEM of the CdSe-C₆₀/TiO₂ composites revealed a homogenous composition in the particles. EDX revealed the presence of C and Ti with strong Cd and Se peaks in the CdSe-C₆₀/TiO₂ composite. The degradation of dye was determined by UV–vis spectrophotometry. An increase in photocatalytic activity was observed and attributed to an increase in the photoabsorption effect by fullerene and the cooperative effect of the CdSe. The repeatability of photocatalytic activity was also tested in order to investigate the stability of C₆₀ and CdS-C₆₀/TiO₂ composites.     

Solvent-induced controllable synthesis of recyclable Ag2CO3 catalysts with enhanced visible light photocatalytic activity

The quest for cost-effective environmental remediation has motivated the research for highly efficient and stable photocatalysts capable of degrading pollutants under visible-light illumination. Ag-based visible-light-responsive photocatalysts demonstrate alluring properties and applications in the elimination of organic pollutants in wastewater, however they often suffer from inherent photo-corrosion under illumination. Herein, we report the facile solution-phase synthesis of silver carbonate (Ag₂CO₃) microcrystals with varied morphological features in different solvents. The size and morphology of Ag₂CO₃ materials can be tuned on the basis of varying types and ratios of solvents. The specific synthetic method allows the orientation controllable growth of Ag₂CO₃ microcrystals with variable length-to-diameter ratios, with the surface harvesting more solar energy, and the photocatalyst suppressing the electron-hole recombination. The enhancement in both the photocatalytic activity and photostability of Ag₂CO₃ catalysts is evident when AgNO₃ and NaHCO₃ are employed as stabilizers. Operating in the presence of 0.02 M stabilizer, the photocatalyst demonstrates highly efficient and robust degradation performance of higher than 95% in 5 successive times towards typical organic dye rhodamine B (RhB). Active holes and reactive oxygen-containing superhydroxyl radicals (·O²⁻) are determined by trapping experiments to be the main species responsible for improved photocatalytic performance. This work provides new insights into the development of high-performance, recyclable Ag-based photocatalytic materials for energy and environmental applications.     

The Z-scheme heterojunction between TiO2 nanotubes and Cu2O nanoparticles mediated by Ag nanoparticles for enhanced photocatalytic stability and activity under visible light

The photocatalytic reduction method was used to introduce Ag nanoparticles (Ag NPs) into the Cu₂O-TiO₂ nanotubes (Cu₂O-TNT) prepared by electrodeposition. The Z-scheme heterojunction Cu₂O-Ag-TNT (CAT-4–60) catalysts were prepared. The mechanism of the transition from the traditional P-N heterojunction enhanced by noble metal to the Z-scheme heterojunction was studied. In addition, the Z-scheme heterojunction CAT-4–60 showed the highest light absorption and the highest photoelectrochemical activity under visible light, and the photoluminescence intensity was significantly reduced. Compared with the traditional P-N heterojunction CAT-2–60, not only the photocatalytic activity of the dual Z-scheme CAT-4–60 catalyst was improved, and the removal rate of MB was 98.58% higher than TNT (45.81%), CT-60 (69.49%), AT-2 (75.1%) and CAT-2–60 (91.2%),but also the stability of Cu₂O in CAT-4–60 was significantly enhanced. This work reveals the potential application of noble metal nanoparticles to enhance the Z-scheme heterojunction under visible light-driven photocatalysis, and provides new insights to the transition from traditional P-N heterojunctions to Z-scheme heterojunctions.     

Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity

N-doped mesoporous TiO₂ nanorods were fabricated by a modified and facile sol–gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N₂, NO₂, and H₂O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO₂ nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m² g^-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle.     

Preparation and photocatalytic properties of RuO2/TiO2 composite nanotube arrays

RuO₂/TiO₂ composite nanotube arrays were prepared using an anodic oxidation method combined with dipping. The photocatalytic properties of RuO₂/TiO₂ nanotube arrays in methylene blue solution were investigated under visible light irradiation. The results showed that Ru existing in the form of RuO₂ was dispersed uniformly on the surface of TiO₂ nanotubes, and the RuO₂ did not change the crystal structure of TiO₂ nanotubes. The load of RuO₂ on TiO₂ had a little influence on the band-gap energy and the absorption band edge, but could increase the amount of Ti-OH functional groups on the surface of TiO₂ nanotubes. The RuO₂/TiO₂ nanotube arrays with the optimal photocatalytic activity were formed in the ruthenium chloride solution with a concentration of 0.0030 mol/L. The 2 h photocatalytic degradation rate of methylene blue increased from 38% for pure TiO₂ nanotubes to 69% for RuO₂/TiO₂ nanotube arrays. This work demonstrated that RuO₂/TiO₂ nanotube arrays showed an improved photocatalytic property over pure TiO₂ nanotubes due to the fact that RuO₂ could capture the photo-generated holes, which greatly decreased the recombination of the photo-generated electrons and holes, and hence lengthen the lifetime of photo-induced electrons and increased the amount of hydroxyl groups absorbed on the TiO₂ nanotubes surface.     

Enhanced visible light response of heterostructured Cr2O3 incorporated two-dimensional mesoporous TiO2 framework for H2 evolution

Mesoporous TiO₂ frameworks incorporated with diverse percentages of Cr₂O₃ nanoparticles (NPs) were achieved through the one-step sol-gel approach for photocatalytic H₂ evolution under visible-light exposure. The obtained isotherms could be classified as type IV, indicating mesopore 2D-hexagonal symmetry. The H₂ evolution rate over mesoporous Cr₂O₃/TiO₂ photocatalyst was observably promoted employing glycerol as a sacrificial agent, providing a comparatively high H₂ yield of 14300 μmolg^?1. The highest photocatalytic efficiency was achieved with an optimal 4% Cr₂O₃/TiO₂ photocatalyst, and the evolution rate was enhanced 1430-fold compared to pristine TiO₂. The eminent photocatalytic performance of mesoporous Cr₂O₃/TiO₂ was ascribable to different key factors such as the narrow bandgap, wide visible light photoresponse, Cr₂O₃ as photosensitizer, synergistic effect and high surface area. The recycle tests for five times over synthesized photocatalyst revealed excellent durability and stability without loss in H₂ evolution. The photocatalytic mechanisms for H₂ evolution over Cr₂O₃/TiO₂ photocatalyst were proposed according to the photocurrent transient and photoluminescence measurements and photocatalytic H₂ evolution results.     

BiOCl/g-C3N4异质结催化剂可见光催化还原CO2

以KCl、Bi（NO₃）₃和类石墨氮化碳（g-C₃N₄）为前体,采用水热法成功制备了BiOCl/g-C₃N₄异质结光催化剂,并进行可见光催化还原CO₂,考察了催化剂的活性及稳定性,同时研究BiOCl：g-C₃N₄（摩尔比）、催化剂用量和光照强度对光催化还原CO₂的影响。结果表明,在水蒸气的存在下,BiOCl/g-C₃N₄较纯BiOCl和g-C₃N₄具有更高的光催化还原CO₂活性,在催化剂用量为0.1 g,光照强度为2.413×10^-6 einstein·min^-1·cm^-2,BiOCl：g-C₃N₄摩尔比为1：1的异质结催化剂显示了最高的光催化还原CO₂活性,且可见光催化剂在5次套用实验后其活性基本不变。基于X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、比表面积测试（BET）和紫外-可见（UV-vis）吸收光谱表征,可以推断BiOCl和g-C₃N₄之间形成的p-n结能有效分离光生电子和空穴,是增强光催化剂活性的主要原因。     

Preparation of Cu2O/exfoliated graphite composites with high visible light photocatalytic performance and stability

Cu₂O/exfoliated graphite composites (Cu₂O/EG (1 wt%), Cu₂O/EG (4 wt%), Cu₂O/EG (7 wt%), Cu₂O/EG (10 wt%), and Cu₂O/EG (15 wt%)) were prepared by the precipitation method. The photocatalytic activity of the material was evaluated using the decolorization of methyl orange (MO) solution as model reaction. Results showed that Cu₂O deposited on the worm-like flakes of EG in the form of nanocrystals. The EG provided a three-dimensional environment for photocatalytic reaction and endowed a high adsorption capacity for the sample. Under optimal conditions, the decolorization efficiencies of MO for 60 min reached 96.7%. Recycling of the catalyst showed Cu₂O/EG composites (10 wt%) to possess high photocatalytic efficiency even when repeatedly used for five times.     

Photocatalytic effect of carbon-modified n-TiO2 nanoparticles under visible light illumination

The present research focused on wet process synthesis of visible light active carbon-modified (CM)-n-TiO₂ nanoparticles and their photocatalytic activity. The CM-n-TiO₂ was synthesized by hydrolysis of TiCl₄ in the presence of tetrabutylammonium hydroxide and also in the presence of glucose and sodium hydroxide. UV–vis spectra, X-ray diffraction (XRD), and FT-IR were used to characterize these photocatalysts. It was found that the CM-n-TiO₂ nanoparticles synthesized by hydrolysis with tetrabutylammonium hydroxide or with sodium hydroxide and glucose when subjected to extended aging and subsequent calcinations absorb well into the visible to near infrared region up to 800 nm and exhibit enhanced visible light photocatalytic activity on degradation of 4-chlorophenol. CM-n-TiO₂ synthesized using glucose as the carbon source generated 13-fold increase in the initial rate of photodegradation of 4-chlorophenol compared to those by regular n-TiO₂, whereas, it increased only eight-fold when tetrabutylammonium hydroxide was used as the carbon source.     

掺钒二氧化钛的可见光催化性能研究

制备高活性可见光响应型掺钒TiO2光催化剂,以荧光灯为光源,光催化降解亚甲基蓝为模型反应,对可见光下TiO2的催化活性进行评价。研究了掺钒TiO2制备方法、掺钒量及氧化剂对光催化氧化的影响。结果表明,溶胶-凝胶法制备的TiO2催化活性较高,且工序简单,钒离子掺杂均匀;掺钒能使TiO2具有可见光响应,最佳掺钒量为1%;外加氧化剂H2O2能提高掺钒TiO2催化活性。     

Simple microwave synthesis of TiO2/NiS2 nanocomposite and TiO2/NiS2/Cu nanocomposite as an efficient visible driven photocatalyst

Approximately 47% of solar-terrestrial radiation is visible. It is a great achievement to produce a highly efficient visible driven photocatalyst. Here TiO₂/NiS₂/Cu nanocomposite was prepared as a highly active visible driven photocatalyst. TiO₂/NiS₂/Cu nanocomposite was prepared by microwave method. It degrades 92%, 86%, 87%, and 88% of Rhodamine B (RhB), Methyl orange (MO), Acid Black 1 (AB1), and Acid Brown 214 (AB214), respectively. Adding NiS₂ and Cu to TiO₂ dramatically increased the degradation efficiency from 17% for bare TiO₂ to 92% for TiO₂/NiS₂/Cu nanocomposite under visible light. As-prepared TiO₂/NiS₂/Cu nanocomposite was characterized by SEM, TEM, XRD, DRS, BET, and EDX.     

Fabrication and characterization of CdS/BiVO4 nanocomposites with efficient visible light driven photocatalytic activities

Novel CdS/BiVO₄ nanocomposites were synthesized by simple solvothermal method. The as-prepared samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectra (DRS), Fourier transform infrared spectra (FT-IR) and photoluminescence (PL). In the nanocomposites, CdS particles were deposited on the surface of the BiVO₄. The photocatalytic tests showed that the CdS/BiVO₄ nanocomposites possessed a higher rate for degradation of malachite green (MG) than the pure BiVO₄ under visible light irradiation. The 1.5-CdS/BiVO₄ nanocomposite photocatalyst was found to degrade 98.3% of MG under visible light irradiation. Moreover, the photocatalytic mechanism of CdS/BiVO₄ nanocomposites was also discussed. The results showed that the nanocomposite construction between CdS and BiVO₄ played a very important role in their photocatalytic properties, which has the potential application in solving environmental pollution issues utilizing solar energy effectively.     

Degradation of phenol in industrial wastewater over the F–Fe/TiO_2 photocatalysts under visible light illumination

F–Fe/TiO_2 composite photocatalyst was synthesized by a facile one-step hydrothermal method and then characterized by XRD, XPS and UV–Vis DRS. The catalyst of F–Fe/TiO_2 exhibited the highest photodegradation rate for phenol as compared with pure TiO_2, F/TiO_2, Fe/TiO_2, F0.38–Fe0.13–TiO_2 and Fe(III)/F-TiO_2 under visible light irradiation. The simulated conditions of industrial phenolic wastewater including initial phenol concentration,visible light intensity, p H and different anions were investigated in the presence of F–Fe/TiO_2 photocatalyst. In addition, as expected, the F–Fe/TiO_2 photocatalyst displayed excellent stability, showing a potential industrial application for the treatment of phenolic wastewater.     

Preparation and characterisation of visible light responsive iodine doped TiO2 electrodes

Characteristics are presented of new iodine doped TiO₂ (I-TiO₂) prepared via the hydrothermal method, where titania (IV) complexes with a ligand containing an iodine atom have been used as a precursor. The structure of samples has been examined by XPS, XRD, UV-vis and FT-IR-ATR techniques. These studies confirm that the obtained powder exhibits a decrease in the bandgap energy value (E_g = 2.8 eV). The report presents electrochemical studies of I-TiO₂ films on a Pt electrode, which allow determination of the flatband potential E_fb = −0.437 V vs. SCE (in 0.5 M Na₂SO₄). Cyclic voltammetry measurements show anodic and cathodic activities under Vis and UV-vis radiation. The photocurrent enhancement due to visible light radiation reached 30% of the whole photoacitivity exhibited under UV-vis illumination.     

Copper reduced defective TiO2 nanoparticles with enhanced visible light photocatalytic activity

Defective TiO₂ attracted increasing attention due to its high photocatalytic activities. Herein, we report a facile and efficient method to fabricate gray defective TiO₂ by vacuum annealing raw TiO₂ materials with copper powders. The treated TiO₂ nanoparticles exhibit significantly enhanced visible‐light‐photocatalytic performance with photo‐degradation rate increased to 400% as that of pristine commercial P25 under visible light. The performance enhancements can be attributed to the disordered structure, optimized optical and electronic properties of defective TiO₂. In addition, this facile Cu reduction method provides an effective way to generate defective sites in other metal oxides for various potential applications.     

Sulfanilic acid-modified P25 TiO2 nanoparticles with improved photocatalytic degradation on Congo red under visible light

Visible-light-induced titania/sulfanilic acid nano-composite photocatalysts were prepared and characterized by FTIR, XPS, UV-vis, XRD, and SEM. The results indicate that the formation of Ti-O-S bonds after the modification of P25 TiO₂ nanoparticles with sulfanilic acid ligands extends the photoresponse of the photocatalyst from the UV to the visible range. The photocatalytic activity of the nano-composite photocatalyst was examined by degrading Congo red under visible light, in which its effecting factors such as irradiation time, catalyst dosage, solution pH and the addition of H₂O₂, were investigated in detail. The possible mechanism of photocatalytic degradation under visible irradiation has been also presented.