A new acidic Ti sol impregnated kaolin photocatalyst: synthesis, characterization and visible light photocatalytic performance

In this study, a photocatalyst with visible light photocatalytic activity was obtained using raw materials, including commercial TiO₂, sulfuric acid, and calcined kaolin (CK). The photocatalyst was prepared via a dissolving/impregnating process, in which acidic Ti sol was obtained by initially dissolving TiO₂ particles in sulfuric acid, and then using the sol as impregnant for the CK. The prepared photocatalyst had wide spectral region and narrow band gap. In addition, the impregnation can create acid sites on the obtained composite surface and consequently improve the activity. A series of tests was performed to characterize the properties of the prepared samples. The visible light photocatalytic degradation of methyl orange (MO) in an aqueous solution was used as a probe reaction to evaluate the photocatalytic activities of the obtained samples. Under visible light irradiation, approximately 80 % of MO (with initial concentration of 20 mg/m³) was degraded in 3 h on the photocatalyst prepared by impregnating CK in acidic Ti sol, which was obtained using approximately 60 % H₂SO₄ solution followed by calcination at 400 °C. The acidity of the photocatalyst is the main factor that affects the catalytic activity of the photocatalytic degradation of MO.     

Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

We successfully prepared Ag quantum dots modified TiO₂ microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO₂ microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO₂ photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO₂ microspheres for methyl orange degradation was proposed in detail.     

花球状Bi2S3/BiOI复合光催化剂去除空气中甲醛的应用

以硫代乙酰胺为硫源,采用水热阴离子转移法,制备由纳米片组装的花球状Bi₂S₃/BiOI复合光催化剂。以气相甲醛作为模型污染物,在检测舱中考察了复合催化剂对甲醛的去除作用。结果表明,具有异质结结构的Bi₂S₃/BiOI复合光催化剂具有较高的光催化活性,能在可见光下去除空气中的甲醛,并且具有良好的循环使用稳定性。     

花球状Bi2S3/BiOI复合光催化剂在空气中净化甲醛的应用

以硫代乙酰胺为硫源,采用水热阴离子转移法,制备由纳米片组装的花球状Bi₂S₃/BiOI复合光催化剂。以气相甲醛作为模型污染物,在检测舱中考察了复合催化剂对甲醛的净化作用。结果表明,具有异质结结构的Bi₂S₃/BiOI复合光催化剂具有较高的光催化活性,能在可见光下净化空气中的甲醛,并且具有良好的循环使用稳定性。     

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。     

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.     

Microwave hydrothermal synthesis and photocatalytic activity of AgIn5S8 for the degradation of dye

AgIn₅S₈ powders were successfully synthesized by a microwave hydrothermal method for the first time. This method is a mild and highly efficient route involves no templates, catalysts, or surfactants. Therefore, it is very promising for the low-cost and large-scale industrial production. The samples were characterized by X-ray diffraction, UV-vis spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The photocatalytic activity of AgIn₅S₈ nanoparticles was investigated through the degradation of methyl orange under visible light irradiation. Compared with TiO_2−xN_x, AgIn₅S₈ has exhibited a superior activity under the same condition. A liquid chromatogram-mass spectrometer was used to separate and identify the dye and degradation products generated during the reaction. According to the experiment results, a possible mechanism for the degradation of organic pollutant over AgIn₅S₈ was proposed.     

A Hierarchical Nanostructured Carbon Nanofiber–In2S3 Photocatalyst with High Photodegradation and Disinfection Abilities Under Visible Light

Photocatalytic degradation of pollutants under visible light provides a new door to solve the water contamination problem by utilizing free and renewable sunlight. The search for highly efficient photocatalysts with hierarchical nanostructures remains crucial for accessing this new door. In this work, a new hierarchical nanostructured photocatalyst is designed and synthesized, for the first time, by anchoring In₂S₃ flower‐like nanostructures on non‐woven carbon nanofiber (CNF). The nanostructures of these CNF–In₂S₃ composites were fine‐tuned, with the aim of achieving the highest photocatalytic activity under visible light. The formation mechanism of the hierarchical nanostructure is also investigated. The results indicate that the optimized hierarchical CNF–In₂S₃ photocatalyst is superior in photodegradation and disinfection efficiency to that of pure In₂S₃ under visible‐light irradiation. The prominent photocatalytic activities of these hierarchical CNF–In₂S₃ photocatalysts can be attributed to the excellent properties of enhanced light absorption, large surface area, and efficient charge separation, which are all derived from the special three‐dimensional hierarchical nanostructures. Therefore, this work presents the great potential of this hierarchical nanostructured CNF–In₂S₃ photocatalyst in practical environmental remediation fields.     

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.     

Preparation,activity and photocatalysis mechanism of high‐performance AgBrO3/AgBr photocatalysts

AgBrO₃/AgBr compound photocatalysts were prepared via a precipitation method and characterized by X‐ray diffraction, field emission scanning electron microscopy, ultraviolet–visible diffusion spectroscopy, and solid surface fluorescence trials. The photocatalytic performances and mechanism were also investigated. It was found the 2.5 wt.% AgBrO₃/AgBr compound photocatalyst was most effective in dye degradation. The AgBrO₃/AgBr showed degradation rate up to 94.5% in a 10 mg/L MO (Methyl Orange) solution and was still very stable after five cycles of reuse. The AgBrO₃/AgBr photocatalysts could oxidize and decompose methyl orange molecules under visible light irradiation. The compounding largely improved the photocatalytic activity of AgBr. Photocatalytic mechanism experiments showed ·OH was the major active species.     

Physicochemcial characteristic of CdS-anchored porous WS2 hybrid in the photocatalytic degradation of crystal violet under UV and visible light irradiation

In this work, we report the synthesis of CdS-incorporated porous WS₂ by a simple hydrothermal method. The structural, morphological, and optical properties of the samples were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), high resolution X-ray photoelectron spectroscopy (XPS) and UV–visible spectrometry. The photocatalytic activities were established for degradation of crystal violet (CV) under UV and visible light irradiation. The CdS-incorporated porous WS₂ hybrid demonstrated high photocatalytic activity for degradation of CV pollutant compared to pure CdS nanoparticles and porous WS₂ sheets. This result implies that the CdS-incorporated porous WS₂ promoted more electron-hole pair transformation under UV and visible light irradiation. This significant enhancement of photocatalytic efficiency of CdS-incorporated porous WS₂ photocatalyst under visible light can be ascribed to the presence of CdS nanospheres on the meshed-like WS₂ sheets which potentially improves absorption in the visible range enabled by surface plasmon resonance effect of CdS nanospheres. The photostability and reusability of the CdS-porous WS₂ were examined through recycling experiments.     

Mercury oxide as an efficient photocatalyst for degradation of rhodamine B dye under visible-light irradiation

In this work, a new visible-light-responsive photocatalyst, mercury oxide (HgO) was successfully developed. Its activity is significantly higher than that of the highly efficient photocatalyst, Ag₃PO₄ in degradation of rhodamine B (RhB) dye under irradiation of visible light. The HgO photocatalyst can be reused for at least three cycles without obvious loss of its activity in the degradation experiments. It was found that the RhB degradation rate is significantly influenced by the dye solution pH. The ultrahigh photocatalytic activity of HgO is attributed to its strong oxidization-ablility of the photogenerated holes, and high separation-possibility of the photogenerated carriers.     

掺镁钛酸钡纳米棒的水热合成和光催化性能

用水热法制备掺镁钛酸钡(Ba1-xMgxTiO3(x=0,0.10,0.20,0.30,0.40),BMT)纳米粉体。运用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、紫外可见漫反射光谱技术(DRS)等手段对样品进行了表征,并在可见光照射下于溶液中考察了其光催化降解甲基橙反应活性。结果表明,通过控制氢氧根浓度可以得到不同形貌的纳米粉体。基于不同条件下制备的样品的微结构分析,提出了这些不同形貌的形成机制。制备出的BMT材料的带隙能约为2.61 eV。光催化反应结果表明BMT的光催化活性比掺氮TiO2高得多。OH-浓度为8 mol·L-1时制备的BMT纳米棒光催化效率最高,经可见光照射360 min,浓度为0.01 mmol·L-1甲基橙溶液的降解率可达到93.0%,且循环使用4次后,其光催化活性并没有明显降低,表明BMT是一种稳定有效的可见光催化剂.     

Synthesis of Nano‐Sized Zinc Oxide Photocatalyst by Combustion Method

The objective of this research was to use combustion synthesis to create a nano‐sized ZnO photocatalyst using citric acid as the fuel and zinc nitrate as the oxidant. The starting materials were mixed in a stoichiometric ratio, and a slurry precursor with high homogeneity was formed. The precursor was ignited at room temperature, resulting in dry, loose, and voluminous ZnO powders. The powders, characterized by SEM, TEM and XRD, showed a particle size range of 40 to 80 nm with a wurtzite structure. The ZnO powders were introduced as a photocatalyst for the degradation of methyl orange, which was adopted as a model compound. UV light (6W) was used as the irradiation source to induce synthesized ZnO powders to perform catalytic activity. The photocatalytic reaction was executed in 40 mL of a 10 ppm methyl orange aqueous solution under 254 nm UV illumination. In this work, it was observed that both UV light and ZnO powders are needed for the photocatalytic reaction. In addition, it was found that increasing the amount of ZnO powder present in the MO (methyl orange‐C₁₄H₁₄N₃NaO₃S) solution did not correlate directly with an increase in photocatalytic ability. It was found that the scattering problem of UV light also needs to be considered. The optimized photocatalytic degradation ratio in this work reached 92.7%.     

Z型复合催化剂g-C3N4/Vo-ZnO光催化活性的研究

随着科学技术的不断进步和经济的快速发展,人类对自然资源的需求量越来越大,在开发利用自然资源的同时,大量的有机污染物也随之进入自然环境.这些物质不仅污染环境、破坏生态,更对人类的生活和健康带来了巨大的威胁.研究证实,半导体光催化剂在光照条件下可以破坏有机污染物的分子结构,最终将其氧化降解成CO2、H2O或其它不会对环境产生二次污染的小分子,从而净化水质.近年来,有关光催化降解有机污染物的报道日益增多. ZnO作为一种广泛研究的光催化降解材料,因其无毒、低成本和高效等特点而具有一定的应用前景.但是ZnO较大的禁带宽度(3.24 eV)导致其只能吸收紫外光部分,而对可见光的吸收效率很小,极大地制约了其实际应用.除此之外, ZnO受光激发产生的电子-空穴分离效率较低、光催化过程中的光腐蚀严重也是制约其实际应用的重要因素.为了提高ZnO的光催化活性和稳定性,本文合成了用g-C3N4修饰的氧空位型ZnO(g-C3N4/Vo-ZnO)复合催化剂,在有效调控ZnO半导体能带结构的同时,通过负载一定量的g-C3N4以降低光生电子-空穴对的复合速率和反应过程中ZnO的光腐蚀,增强催化剂的光催化活性和稳定性.本文首先合成前驱体Zn(OH)F,然后焙烧三聚氰胺和Zn(OH)F的混合物得到g-C3N4/Vo-ZnO复合催化剂,并采用电子顺磁共振波谱(EPR)、紫外-可见光谱(UV-vis)、高分辨透射电镜(HRTEM)和傅里叶变换红外光谱(FT-IR)等表征了它们的结构及其性质. EPR结果表明,ZnO焙烧后具有一定浓度的氧空位,导致其禁带宽度由3.24 eV降至3.09 eV,因而提高了ZnO对可见光的吸收效率. UV-vis结果显示, Vo-ZnO复合g-C3N4后对可见光的吸收显著增强. HRTEM和FT-IR结果均表明, g-C3N4纳米片和Vo-ZnO颗粒之间通过共价键形成了强耦合,这对g-C3N4/Vo-ZnO复合催化剂中光生载流子的传送和光生电子-空穴对的有效分离起到重要作用.可见光催化降解甲基橙(MO)和腐殖酸(HA)的实验进一步证明, g-C3N4/Vo-ZnO复合材料具有较好的光催化活性,优于单一的g-C3N4或Vo-ZnO材料.同时还发现, g-C3N4的负载量对光催化活性有显著影响,当氮化碳的负载量为1 wt%时,所制材料具有最高的光催化活性：可见光照射60 min后,MO降解率可达到93%, HA降解率为80%.复合材料光催化活性的增强一方面是因为氧空位的形成减小了ZnO的禁带宽度,使得ZnO对可见光的吸收能力大大增强;另一方面, g-C3N4和Vo-ZnO的能带符合了Z型催化机理所需的有效能带匹配,使得光生电子-空穴对得到了有效的分离,从而提高了光催化活性.降解MO的循环实验表明, g-C3N4/Vo-ZnO催化剂具有很好的稳定性且不容易发生光腐蚀.与此同时,我们对比了用不同方法制备的g-C3N4/ZnO材料的催化性能.结果显示,本文制备的g-C3N4/Vo-ZnO复合材料具有更好的降解效率.总体而言,对于降解有机污染物, g-C3N4/Vo-ZnO可能是一个更为有效可行的催化体系.此外,本文也为设计与制备其他新型光催化剂提供了一条新的思路.     

Fe3+掺杂TiO2/凹凸棒复合光催化剂的制备和光催化活性

用酸催化溶胶-凝胶法制备了Fe³⁺掺杂TiO₂/凹凸棒（Fe³⁺-TiO₂/ATP）复合光催化剂,对其结构、微观形貌、光吸收性能和可见光下的光催化性能进行了表征。XRD和TEM测试结果表明,Fe³⁺-TiO₂/ATP具有较好的热稳定性,经450 ℃热处理后的ATP晶体结构基本保持不变,锐钛矿TiO2均匀的分布在ATP表面,TiO2颗粒之间无团聚,且平均粒径小于纯TiO₂。UV-Vis-DRS测试结果表明,Fe³⁺的掺杂可明显增强复合光催化剂对可见光的吸收,光响应范围拓展到了整个紫外-可见光区。在可见光下,Fe³⁺-TiO₂/ATP复合光催化剂对亚甲基蓝具有很好的催化降解活性。Fe³⁺-TiO₂/ATP的反应速率常数分别为TiO₂/ATP、P25和纯TiO2的1.37、4.83和6.51倍。复合光催化剂的沉降性能优于纯TiO2和P25,易于分离。     

S-doped graphene quantum dots as nanophotocatalyst for visible light degradation

S-doped graphene quantum dots (S-GQDs) with well crystallization and monodispersity were prepared and applied as novel nanophotocatalyst for visible light degradation of basic fuchsin.     

有机改性TiO2光催化剂的制备及可见光催化性能

以染料黄叱精(Chrysoidine G)和TiO₂ (Degussa P25)为原料, 利用甲苯二异氰酸酯为桥连体, 成功合成了一种有机改性的TiO₂光催化剂. 采用XRD, TEM, FT-IR, UV-Vis对所得催化剂进行了表征, 以亚甲基蓝降解为探针反应, 考察其可见光催化性能. 结果表明: 甲苯二异氰酸酯在黄叱精和TiO₂之间形成了稳定的化学键, 从而实现了对TiO₂的表面有机改性; 改性后的TiO₂在可见光区(400～550 nm)有明显的吸收; 与未改性TiO₂相比, 有机改性的TiO₂催化剂在可见光照射下表现出了很好的光催化性能.     

Facile Biosynthesis of Calcium Hydroxide Nanoparticles Using <Emphasis Type="Italic">Andrographis echioides</Emphasis> Leaf Extract and Its Photocatalytic Activity Under Different Light Source

Effective removal of organic pollutants from wastewater becomes notable research because of its ecological and environmental importance. In the present study Andrographis echioides leaf extract was used for the synthesis of calcium hydroxide nanoparticles (Ca(OH)₂-NPs) from calcium oxide as the calcium source. The secondary metabolites present in the plant source act as a capping agent for the formation Ca(OH)₂-NPs. Further NPs were applied for photocatalytic degradation. The intention of the approach is to be low-cost preparation and easy degradation (degradation of dye without any effect) to the environment. The synthesized Ca(OH)₂-NPs was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultra violet diffuse reflectance spectroscopy, energy dispersive X-ray spectroscopy, zeta potential and high-resolution transmission electron microscopy. The photocatalytic degradation of methylene blue (dye pollutant) studied under three different light sources such as UV, visible and sun light using Ca(OH)₂-NPs. Degradation efficiency of Methylene blue dye examined under UV–Vis spectroscopy. Degradation percentage of Ca(OH)₂-NPs under UV, visible and sunlight are (98.96, 97.52 and 96.38%) respectively. The overall study suggests that Ca(OH)₂-NPs exhibit excellent photocatalytic property against UV, visible and sunlight.     

Synthesis and photocatalytic properties of core–shell TiO~2@ZnIn_2S_4 photocatalyst

A novel core–shell TiO2@ZnIn2S4composite has been synthesized successfully by a simple and flexible hydrothermal route using TiO2as precursors.The as-synthesized samples were characterized by X-ray diffraction,UV–vis diffuse reflectance spectra and transmission electron microscopy.The photocatalytic properties of samples were tested by degradation of aqueous methylene blue（MB）under visible light irradiation.It was found that the as-synthesized TiO2@ZnIn2S4photocatalyst was more effcient than TiO2and ZnIn2S4in the photocatalytic degradation of MB.Moreover,TEM images confrmed the TiO2@ZnIn2S4nanoparticles possessed a well-proportioned core–shell morphology.