Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant...Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation.Effects of various parameters such as catalyst amount,initial MO concentration,solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions.The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model,and a surface reaction,where the dyes are absorbed,is the controlling step of the process.Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range.The photodecolorization of MO is more efficient in acidic media than alkaline media.The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation,which confirms the reusability of AC/n-CdS/CS composite catalyst.展开更多
The sanitary and environmental challenges posed by an ever growing economically and geographically diverse human population include the need for sustainable, inexpensive, scalable, and decentralized water treatment te...The sanitary and environmental challenges posed by an ever growing economically and geographically diverse human population include the need for sustainable, inexpensive, scalable, and decentralized water treatment technologies that can supplement or replace conventional treatment methods. These challenges can be met by semiconductor photocatalysis, especially if the process is driven by visible light energy. Visible-light active (VLA) photocatalysis, as opposed to traditional energy-intensive and chemically driven disinfection methods such as ozonation, UV irradiation and chlorination, has the potential for achieving high disinfection efficiency with low energy consumption and no harmful by-products. This technology generates in-situ reactive oxygen species (ROS) such as H2O2, and?, without the need for chemicals addition. In turn, ROS are capable of penetrating cell walls and membranes of microorganisms, effectively inactivating them. Although multiple types of VLA photocatalysts have been used experimentally for disinfection of water, noble-metal-based photocatalysts have gained the most interest due to their surface plasma resonance (SPR) effect, which acts synergistically to increase the disinfection potential of the photocatalytic process. This paper is a review of the different types of noble-metal-based VLA photocatalysts used for water disinfection in different experimental settings, their synthesis procedures and disinfection mechanisms. It also discusses innovative approaches to overcome a major hurdle in photocatalysis, that is, the rapid recombination of the electron and hole pair, by including specific dopants into the structure of the photocatalyst.展开更多
In order to develop the high photocatalytic activity of TiO2 under visible light as that under ultraviolet light and make it easy to be separated from treated liquor, a visible light response and spherical activated c...In order to develop the high photocatalytic activity of TiO2 under visible light as that under ultraviolet light and make it easy to be separated from treated liquor, a visible light response and spherical activated carbon （SAC） supported photocatalyst doped with upconversion luminescence agent Er3＋：YAlO3 was prepared by immobilizing Er3＋：YAlO3/TiO2, which was obtained by combination of Er3＋：YAlO3 and TiO2 using sol-gel method, on the surface of SAC. The crystal phase composition, surface structure and element distribution, and light absorption of the new photocatalysts were examined by X-ray diffraction （XRD）, energy dispersive X-ray spectra （EDS） analysis, scanning electron microscopy （SEM） and fluorescence spectra analysis （FSA）. The photocatalytic oxidation activity of the photocatalysts was also evaluated by the photodegradation of methyl orange （MO） in aqueous solution under visible light irradiation from a LED lamp （λ400 nm）. The results showed that Er3＋：YAlO3 could perform as the upconversion luminescence agent which converts the visible light up to ultraviolet light. The Er3＋：YAlO3/TiO2 calcinated at 700 °C revealed the highest photocatalytic activity. The apparent reaction rate constant could reach 0.0197 min-1 under visible light irradiation.展开更多
Undoped and Ni–S co-doped mesoporous TiO2 nano materials were synthesized by using sol–gel method.The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic an...Undoped and Ni–S co-doped mesoporous TiO2 nano materials were synthesized by using sol–gel method.The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic and analytical techniques.The characterization results of the samples revealed that all the samples exhibited anatase phase(XRD),decreasing band gap(2.68 eV)(UV–Vis-DRS),small particle size(9.2 nm)(TEM),high surface area(142.156 m^2·g^-1)(BET),particles with spherical shape and smooth morphology(SEM);there is a frequency shift observed for co-doped sample(FT-IR)and the elemental composition electronic states and position of the doped elements(Ni and S)in the TiO2 lattice analyzed by XPS and EDX.These results supported the photocatalytic degradation of Bismarck Brown Red(BBR)achieved with in 110 min and also exhibited the antibacterial activity on Staphylococcus aureus(MTCC-3160),Pseudomonas fluorescence(MTCC-1688)under visible light irradiation.展开更多
A visible-light-active photocatalyst was prepared by calcination of the hydrolysis product of tetrabutyl titanate with ammonia as precipitant. The photocatalyst was characterized by X-ray diffraction (XRD), UV-Vis dif...A visible-light-active photocatalyst was prepared by calcination of the hydrolysis product of tetrabutyl titanate with ammonia as precipitant. The photocatalyst was characterized by X-ray diffraction (XRD), UV-Vis diffuse reflection spectra (DRS), thermal gravimetric-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM). The color of the photocatalyst was yellow and could absorb light wavelength under 550 nm as measured by DRS. The catalyst calcined at higher temperature will give lower absorbance for visible light. Structures of the sample were characterized mainly to be anatase by XRD except for the sample calcined at 700 ℃ which gave mixtures of anatase and rutile. TG-DTA results showed that temperature for anatase formation was 415 ℃. XPS results showed that doped-nitrogen was presented in the sample, they are important to show visible-light absorbency. The photocatalytic activities were evaluated using methyl orange and phenol as model pollutants, the results showed that over 90% of phenol could be degraded under visible light using N/TiO2 as the catalyst after 4 hours reaction. Almost the same activity was found for the TiO2 photocatalyst calcined at different temperature under sunlight but activities were different when the treatment was under UV light.展开更多
以氮掺杂为代表的非金属掺杂型TiO2光催化剂被誉为"第二代光催化材料"。本文首先系统评述了氮掺杂二氧化钛的制备方法,然后详细阐述了在N掺杂TiO2研究中关于其可见光活性机制以及掺杂N在TiO2晶格中的存在状态等方面的争议。N...以氮掺杂为代表的非金属掺杂型TiO2光催化剂被誉为"第二代光催化材料"。本文首先系统评述了氮掺杂二氧化钛的制备方法,然后详细阐述了在N掺杂TiO2研究中关于其可见光活性机制以及掺杂N在TiO2晶格中的存在状态等方面的争议。N掺杂TiO2粉末的制备方法主要有氨气气氛下的热处理工艺、水解沉淀法、溶胶-凝胶法以及机械化学法等;N掺杂TiO2薄膜的制备方法主要包括磁控溅射法、脉冲激光沉积法以及金属有机化学气相沉积法等。已提出的关于N掺杂TiO2可见光活性机制的观点有N2p与O2p能级相杂化、形成N 2p孤立能态、氧空位的作用以及具顺磁性特征的杂质敏化。关于掺杂N在TiO2晶格中存在状态的分歧在于XPS N 1s谱中特征峰的位置及其归属的解析。文章最后指出了氮掺杂TiO2催化剂研究中有待解决的问题及今后的发展方向。展开更多
基金Project(21007044) supported by the National Natural Science Foundation of ChinaProject(20050532009) supported by the Doctoral Foundation of Ministry of Education of China
文摘Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation.Effects of various parameters such as catalyst amount,initial MO concentration,solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions.The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model,and a surface reaction,where the dyes are absorbed,is the controlling step of the process.Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range.The photodecolorization of MO is more efficient in acidic media than alkaline media.The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation,which confirms the reusability of AC/n-CdS/CS composite catalyst.
文摘The sanitary and environmental challenges posed by an ever growing economically and geographically diverse human population include the need for sustainable, inexpensive, scalable, and decentralized water treatment technologies that can supplement or replace conventional treatment methods. These challenges can be met by semiconductor photocatalysis, especially if the process is driven by visible light energy. Visible-light active (VLA) photocatalysis, as opposed to traditional energy-intensive and chemically driven disinfection methods such as ozonation, UV irradiation and chlorination, has the potential for achieving high disinfection efficiency with low energy consumption and no harmful by-products. This technology generates in-situ reactive oxygen species (ROS) such as H2O2, and?, without the need for chemicals addition. In turn, ROS are capable of penetrating cell walls and membranes of microorganisms, effectively inactivating them. Although multiple types of VLA photocatalysts have been used experimentally for disinfection of water, noble-metal-based photocatalysts have gained the most interest due to their surface plasma resonance (SPR) effect, which acts synergistically to increase the disinfection potential of the photocatalytic process. This paper is a review of the different types of noble-metal-based VLA photocatalysts used for water disinfection in different experimental settings, their synthesis procedures and disinfection mechanisms. It also discusses innovative approaches to overcome a major hurdle in photocatalysis, that is, the rapid recombination of the electron and hole pair, by including specific dopants into the structure of the photocatalyst.
基金Projects (50908096, 50908097) supported by the National Natural Science Foundation of ChinaProject (20100471251) supported by China Postdoctoral Science Foundation
文摘In order to develop the high photocatalytic activity of TiO2 under visible light as that under ultraviolet light and make it easy to be separated from treated liquor, a visible light response and spherical activated carbon （SAC） supported photocatalyst doped with upconversion luminescence agent Er3＋：YAlO3 was prepared by immobilizing Er3＋：YAlO3/TiO2, which was obtained by combination of Er3＋：YAlO3 and TiO2 using sol-gel method, on the surface of SAC. The crystal phase composition, surface structure and element distribution, and light absorption of the new photocatalysts were examined by X-ray diffraction （XRD）, energy dispersive X-ray spectra （EDS） analysis, scanning electron microscopy （SEM） and fluorescence spectra analysis （FSA）. The photocatalytic oxidation activity of the photocatalysts was also evaluated by the photodegradation of methyl orange （MO） in aqueous solution under visible light irradiation from a LED lamp （λ400 nm）. The results showed that Er3＋：YAlO3 could perform as the upconversion luminescence agent which converts the visible light up to ultraviolet light. The Er3＋：YAlO3/TiO2 calcinated at 700 °C revealed the highest photocatalytic activity. The apparent reaction rate constant could reach 0.0197 min-1 under visible light irradiation.
基金the University Grants Commission (UGC) for providing BSR fellowship
文摘Undoped and Ni–S co-doped mesoporous TiO2 nano materials were synthesized by using sol–gel method.The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic and analytical techniques.The characterization results of the samples revealed that all the samples exhibited anatase phase(XRD),decreasing band gap(2.68 eV)(UV–Vis-DRS),small particle size(9.2 nm)(TEM),high surface area(142.156 m^2·g^-1)(BET),particles with spherical shape and smooth morphology(SEM);there is a frequency shift observed for co-doped sample(FT-IR)and the elemental composition electronic states and position of the doped elements(Ni and S)in the TiO2 lattice analyzed by XPS and EDX.These results supported the photocatalytic degradation of Bismarck Brown Red(BBR)achieved with in 110 min and also exhibited the antibacterial activity on Staphylococcus aureus(MTCC-3160),Pseudomonas fluorescence(MTCC-1688)under visible light irradiation.
文摘A visible-light-active photocatalyst was prepared by calcination of the hydrolysis product of tetrabutyl titanate with ammonia as precipitant. The photocatalyst was characterized by X-ray diffraction (XRD), UV-Vis diffuse reflection spectra (DRS), thermal gravimetric-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM). The color of the photocatalyst was yellow and could absorb light wavelength under 550 nm as measured by DRS. The catalyst calcined at higher temperature will give lower absorbance for visible light. Structures of the sample were characterized mainly to be anatase by XRD except for the sample calcined at 700 ℃ which gave mixtures of anatase and rutile. TG-DTA results showed that temperature for anatase formation was 415 ℃. XPS results showed that doped-nitrogen was presented in the sample, they are important to show visible-light absorbency. The photocatalytic activities were evaluated using methyl orange and phenol as model pollutants, the results showed that over 90% of phenol could be degraded under visible light using N/TiO2 as the catalyst after 4 hours reaction. Almost the same activity was found for the TiO2 photocatalyst calcined at different temperature under sunlight but activities were different when the treatment was under UV light.
文摘以氮掺杂为代表的非金属掺杂型TiO2光催化剂被誉为"第二代光催化材料"。本文首先系统评述了氮掺杂二氧化钛的制备方法,然后详细阐述了在N掺杂TiO2研究中关于其可见光活性机制以及掺杂N在TiO2晶格中的存在状态等方面的争议。N掺杂TiO2粉末的制备方法主要有氨气气氛下的热处理工艺、水解沉淀法、溶胶-凝胶法以及机械化学法等;N掺杂TiO2薄膜的制备方法主要包括磁控溅射法、脉冲激光沉积法以及金属有机化学气相沉积法等。已提出的关于N掺杂TiO2可见光活性机制的观点有N2p与O2p能级相杂化、形成N 2p孤立能态、氧空位的作用以及具顺磁性特征的杂质敏化。关于掺杂N在TiO2晶格中存在状态的分歧在于XPS N 1s谱中特征峰的位置及其归属的解析。文章最后指出了氮掺杂TiO2催化剂研究中有待解决的问题及今后的发展方向。
