A series of novel AgCl/AgaCO3 heterostructured photocatalysts with different AgCl contents （5 wt%, 10 wt%, 20 wt%, and 30 wt%） were prepared by facile coprecipitation method at room temperature. The resulting produc...A series of novel AgCl/AgaCO3 heterostructured photocatalysts with different AgCl contents （5 wt%, 10 wt%, 20 wt%, and 30 wt%） were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS）, and ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS）, respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange （MO） under UV light irradiation. With the optimal AgCl content of 20 wt%, the AgCl/AgECO3 composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant （0.67 h^-1） is 5.2 times faster than that of Ag2CO3 （0.13 h^-1）, and 16.8 times faster than that of AgCl （0.04 h^-1）. The formation of AgCl/AgaCO3 heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.展开更多
UiO-66-NH2, as typical visible light responsive Zr-based metal-organic frameworks (MOFs), has attracted great interest in recent years. However, rapid combination of the photoinduced carriers limits its further applic...UiO-66-NH2, as typical visible light responsive Zr-based metal-organic frameworks (MOFs), has attracted great interest in recent years. However, rapid combination of the photoinduced carriers limits its further application. Here, we designed a facile precipitation-photoreduction method to post-synthetically decorate Ag/AgCl on the surface of UiO-66-NH2 and form a heterostructure. Metallic Ag can not only transmit electrons between UiO-66-NH2 and AgCl but also absorb visible light, because of the surface plasmon resonance (SPR) effect. The rhodamine B photodegradation rate of UiO-66-NH2/Ag/AgCl (16.2 wt.% Ag) is about 10 and 4 times those of UiO-66-NH2 and Ag/AgCl, respectively. The SPR effect of Ag NPs and the formation of a heterostructure synergistically increase the absorbability of visible light, accelerate the separation of photoinduced charges, and promote the formation of superoxide radicals. We expect that our work could provide a new viewpoint for constructing efficient MOF-based photocatalytic systems.展开更多
In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion metho...In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion method,a green alternative to the traditional preparative routes.The catalyst was characterized using XRD,FTIR,SEM,EDX,XPS and TEM techniques.The synergistic effect of the composite CeO2/g-C3 N4/Ag was tested for catalytic reduction of 4-nitrophenol in the prese nce of sodium borohydride.The reaction was carried out at room tempe rature without any light source or exte rnal stirring.The individual and combined effects of four parameters,viz.,concentration of 4-NP,amount of catalyst,amount of NaBH4 and time for the reduction of reduction 4-NP were investigated using Box-Behnken design of response surface methodology(RSM).This statistical model was used to optimize the reaction conditions for maximum reduction of 4-NP.The optimum conditions for the reduction reaction are found to be 0.01 mmol/L 4-NP,15 mg catalyst,20 mg NaBH4 and 13.7 min time interval.展开更多
The synthesis of ultrafine cerium dioxide precursor via homogeneous precipitation was studied. Mixed aqueous solution of anhydrous cerium nitrate and urea was first heated to 85℃ for 2 h, and the prepared suspension ...The synthesis of ultrafine cerium dioxide precursor via homogeneous precipitation was studied. Mixed aqueous solution of anhydrous cerium nitrate and urea was first heated to 85℃ for 2 h, and the prepared suspension was then aged at room temperature for various periods of time. White precipitate was finally collected by centrifuging and washed with distilled water and anhydrous ethanol. The obtained cerium dioxide (CeO2) precursor was observed with SEM. It was found that the morphology and size of the precursor were strongly affected by aging time and stirring conditions (with or without stirring). The precipitated fine spherical particles of the precursor changed their shape from ellipse to slice or directly to slice. Fine spherical monodispersed (300 nm) precursor powders could be obtained by controlling the aging time. Stirring the solution also could change the reaction process and thus the morphology and size of the precursor were changed.展开更多
Ag/AgCl/TiO^(2)nanocomposite was synthesized through the combination of sol-gel process and hydrothermal(HT)method followed by ion exchange method in the paper.Transmission electron microscope,UVevis absorption proper...Ag/AgCl/TiO^(2)nanocomposite was synthesized through the combination of sol-gel process and hydrothermal(HT)method followed by ion exchange method in the paper.Transmission electron microscope,UVevis absorption property and X-ray diffraction were utilized to characterize the morphology,optical absorption property and phase structure of the as-prepared photocatalysts.The morphological and performance studies of Ag/AgCl/TiO^(2)revealed that a well-interconnected mixed phase heterojunction photocatalyst was achieved through as-prepared TiO^(2)and the subsequent ion exchange method.By the degradation of Rhodamine B under xenon lamp,Ag/AgCl/TiO^(2)exhibited a significant enhancement in photocatalytic activity compared with TiO^(2)and Ag/TiO^(2).The band gap of Ag/AgCl/TiO^(2)can reach to 2.53eV compared with 3.22eV of the prepared TiO^(2).Furthermore,the synthesis process and photoreaction mechanisms of TiO^(2),Ag/TiO^(2)and Ag/AgCl/TiO^(2)photocatalysts were proposed.It demonstrated that the enhancement of photocatalytic was mainly due to the reducing of electron-hole recombination in Ag/AgCl/TiO^(2).展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21067004 and21263005)the Young Science and Technology Project of Jiangxi Province Natural Science Foundation(No.20133BAB21003)+1 种基金the Young Scientist Training Project of Jiangxi Province(No.20122BCB23015)the Science and Technology Landing Project of Jiangxi Province Education Office(No.KJLD14046)
文摘A series of novel AgCl/AgaCO3 heterostructured photocatalysts with different AgCl contents （5 wt%, 10 wt%, 20 wt%, and 30 wt%） were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS）, and ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS）, respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange （MO） under UV light irradiation. With the optimal AgCl content of 20 wt%, the AgCl/AgECO3 composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant （0.67 h^-1） is 5.2 times faster than that of Ag2CO3 （0.13 h^-1）, and 16.8 times faster than that of AgCl （0.04 h^-1）. The formation of AgCl/AgaCO3 heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.
基金supported by the National Natural Science Foundation of China(21676182)the National Basic Research Program of China(973 Program,2014CB932403)the Program for Introducing Talents of Discipline to Universities of China(B06006)
文摘UiO-66-NH2, as typical visible light responsive Zr-based metal-organic frameworks (MOFs), has attracted great interest in recent years. However, rapid combination of the photoinduced carriers limits its further application. Here, we designed a facile precipitation-photoreduction method to post-synthetically decorate Ag/AgCl on the surface of UiO-66-NH2 and form a heterostructure. Metallic Ag can not only transmit electrons between UiO-66-NH2 and AgCl but also absorb visible light, because of the surface plasmon resonance (SPR) effect. The rhodamine B photodegradation rate of UiO-66-NH2/Ag/AgCl (16.2 wt.% Ag) is about 10 and 4 times those of UiO-66-NH2 and Ag/AgCl, respectively. The SPR effect of Ag NPs and the formation of a heterostructure synergistically increase the absorbability of visible light, accelerate the separation of photoinduced charges, and promote the formation of superoxide radicals. We expect that our work could provide a new viewpoint for constructing efficient MOF-based photocatalytic systems.
文摘In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion method,a green alternative to the traditional preparative routes.The catalyst was characterized using XRD,FTIR,SEM,EDX,XPS and TEM techniques.The synergistic effect of the composite CeO2/g-C3 N4/Ag was tested for catalytic reduction of 4-nitrophenol in the prese nce of sodium borohydride.The reaction was carried out at room tempe rature without any light source or exte rnal stirring.The individual and combined effects of four parameters,viz.,concentration of 4-NP,amount of catalyst,amount of NaBH4 and time for the reduction of reduction 4-NP were investigated using Box-Behnken design of response surface methodology(RSM).This statistical model was used to optimize the reaction conditions for maximum reduction of 4-NP.The optimum conditions for the reduction reaction are found to be 0.01 mmol/L 4-NP,15 mg catalyst,20 mg NaBH4 and 13.7 min time interval.
基金the Natural Science Foundation of Jiangsu Province under pro ject No.BK2002010.
文摘The synthesis of ultrafine cerium dioxide precursor via homogeneous precipitation was studied. Mixed aqueous solution of anhydrous cerium nitrate and urea was first heated to 85℃ for 2 h, and the prepared suspension was then aged at room temperature for various periods of time. White precipitate was finally collected by centrifuging and washed with distilled water and anhydrous ethanol. The obtained cerium dioxide (CeO2) precursor was observed with SEM. It was found that the morphology and size of the precursor were strongly affected by aging time and stirring conditions (with or without stirring). The precipitated fine spherical particles of the precursor changed their shape from ellipse to slice or directly to slice. Fine spherical monodispersed (300 nm) precursor powders could be obtained by controlling the aging time. Stirring the solution also could change the reaction process and thus the morphology and size of the precursor were changed.
基金the National Natural Science Foundation of China under Grant No.51762028 and No.11504146.
文摘Ag/AgCl/TiO^(2)nanocomposite was synthesized through the combination of sol-gel process and hydrothermal(HT)method followed by ion exchange method in the paper.Transmission electron microscope,UVevis absorption property and X-ray diffraction were utilized to characterize the morphology,optical absorption property and phase structure of the as-prepared photocatalysts.The morphological and performance studies of Ag/AgCl/TiO^(2)revealed that a well-interconnected mixed phase heterojunction photocatalyst was achieved through as-prepared TiO^(2)and the subsequent ion exchange method.By the degradation of Rhodamine B under xenon lamp,Ag/AgCl/TiO^(2)exhibited a significant enhancement in photocatalytic activity compared with TiO^(2)and Ag/TiO^(2).The band gap of Ag/AgCl/TiO^(2)can reach to 2.53eV compared with 3.22eV of the prepared TiO^(2).Furthermore,the synthesis process and photoreaction mechanisms of TiO^(2),Ag/TiO^(2)and Ag/AgCl/TiO^(2)photocatalysts were proposed.It demonstrated that the enhancement of photocatalytic was mainly due to the reducing of electron-hole recombination in Ag/AgCl/TiO^(2).
