The photocatalytic degradation of dye Rhodamine B (RhB) in the presence of TiO2 nanostdpe or P25 under visible light irradiation was investigated. The degradation intermediates were identified using Infrared spectra...The photocatalytic degradation of dye Rhodamine B (RhB) in the presence of TiO2 nanostdpe or P25 under visible light irradiation was investigated. The degradation intermediates were identified using Infrared spectra (IR spectra), ^1H nuclear magnetic resonance (^1HNMR) spectra, and gas chromatography-mass spectroscopy (GC-MS). The IR and the ^1HNMR results showed that the large conjugated chromophore structure of RhB was efficiently destroyed under visible light irradiation in both the photocatalytic systems (TiO2 nanostfipe or P25 and Rhodamine B systems). GC-MS results showed that the main identified intermediates were ethanediotic acid, 1,2-benzenedicarboxylic acid, 4-hydroxy benzoic acid and benzoic acid, which were almost the same in the TiO2 nanostdpes and P25 systems. This work provides a good insight into the reaction pathway(s) for the TiO2-assisted photocatalytic degradation of dye pollutants under visible light irradiation.展开更多
Nonylphenol(NP)residues,as a typical endocrine disrupting chemical(EDC),frequently exist in sewage,surface water,groundwater and even drinking water,which poses a serious threat to human health due to its bioaccumulat...Nonylphenol(NP)residues,as a typical endocrine disrupting chemical(EDC),frequently exist in sewage,surface water,groundwater and even drinking water,which poses a serious threat to human health due to its bioaccumulation.In order to remove NP,a series of MIL-100(Fe)/Zn Fe_(2)O_(4)/flake-like porous carbon nitride(MIL/ZC)was synthesized through in-situ synthesis at room temperature.High performance of ternary MIL/ZC is used to degrade NP under visible light irradiation.The results show that 30MIL/ZC2(20 wt.%Zn Fe_(2)O_(4))ternary composite had the best photocatalytic activity(99.84%)when the dosage was 30 mg.Further mechanism analysis shows that the excellent photocatalytic activity of 30MIL/ZC2could be ascribed to the double charge transfer process between flake-like porous carbon nitride(PCN)and other catalysts in the ternary heterojunction,and the separation of photogenerated electron-hole pairs was more effective.In addition,the 30MIL/ZC2 also showed high stability after five cycles of the photodegradation reaction.Furthermore,the active substance(·O_(2)^(-))was considered to be the main active substance in the NP degradation process.Based on the research results,the possible photocatalytic reaction mechanism of 30MIL/ZC2ternary composite was proposed and discussed in detail.展开更多
Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surfac...Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.展开更多
The selective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) is an important reaction for renewable biomass building blocks. Compared with thermal catalytic processes, photocatalytic production ...The selective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) is an important reaction for renewable biomass building blocks. Compared with thermal catalytic processes, photocatalytic production of DFF from HMF has attracted tremendous attention. Herein, the MoS_(2)/CdIn_(2)S_(4)(MC)flower-like heterojunctions were prepared and considered as photocatalysts for selective oxidation of HMF into DFF under visible-light irradiation in aqueous solution. Results demonstrated MoS_(2) in MC heterojunction could promote the separation of photoexcited electron-hole pairs, while the amount of MoS_(2) dropping was proved influenced on the photocatalytic performance. 80.93% of DFF selectivity was realized when using 12.5% MC as photocatalyst. In addition, the MC catalyst also showed great potential in transformation of other biomass derived benzyl-and furyl-alcohols. The catalytic mechanism suggested that ·O_(2)^(-) was the decisive active radical for HMF oxidation. Therefore, the MC heterojunction could be applied in photocatalytic conversion of biomass to valuable chemicals under ambient condition.展开更多
Nanoflower-like ZnO-C_(3)N_(4) thin film with a porous net structure was successfully synthesized by a simple chemical corrosion method.The prepared ZnOC_(3)N_(4) thin films presented remarkable photocatalytic activit...Nanoflower-like ZnO-C_(3)N_(4) thin film with a porous net structure was successfully synthesized by a simple chemical corrosion method.The prepared ZnOC_(3)N_(4) thin films presented remarkable photocatalytic activities for the degradation of methyl orange under visible light irradiation,and more than 90%methyl orange was removed from water by ZnO-C_(3)N_(4) composite.Meanwhile,the ZnO-C_(3)N_(4) composite presented an enhanced photocatalytic stability.The loading content of C_(3)N_(4) had a great effect on the photocatalytic performance.Moreover,the photocatalytic activities were higher in acidic media than those in alkaline conditions.The adsorption of methyl orange was enhanced,and the recombination of photogenerated electrons and holes was suppressed with a suitable content of C_(3)N_(4).However,too much loading content of C_(3)N_(4) resulted in a poor dispersion of C_(3)N_(4) as the aggregated C_(3)N_(4) can behave as recombination centers.In addition,the prepared ZnO-C_(3)N_(4) thin film can be used for the water splitting in water-methanol system under simulated solar light irradiation.展开更多
Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4(CNS) Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization r...Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4(CNS) Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3 N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for guest molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe2 O3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe2 O3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe2 O3 and CNS components toward the photocatalytic degradation of methylene blue(MB). The optimal loaded Fe2 O3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min(-1) which was faster than those of the pure Fe2 O3(0.0016 min(-1))and CNS(0.0044 min(-1)) under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe2 O3(6.6)/CNS hybrid are 33.5 m2/g and0.195 cm3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe2 O3(6.6)/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured(at pH = 7) equal to-1.07 and 1.48 V versus normal hydrogen electrode(NHE), respectively.Trapping tests prove that ·OH-and ·O2-radicals are major active species in the photocatalytic reaction.It has been established that formation of the Z-scheme Fe2 O3(6.6)/CNS heterojunction between CNS and Fe2 O3 directly produces ·OH as well as ·O2-radicals which is consistent with the results obtained from trapping experiments.展开更多
Highly crystalline orthorhombic Bi2WO6 powders were hydrothermally synthesized from aqueous solutions of Na2WO4 · 2H2O and Bi (NO3)3 · 5H2O over a wide range of pH. The effect of pH on morphologies, sizes ...Highly crystalline orthorhombic Bi2WO6 powders were hydrothermally synthesized from aqueous solutions of Na2WO4 · 2H2O and Bi (NO3)3 · 5H2O over a wide range of pH. The effect of pH on morphologies, sizes and properties of the Bi2WO6 crystals was investigated. The band gaps of the as-prepared Bi2WO6 were determined from the onset of the absorption edge of UV-vis diffuse reflectance spectra. The methyl orange photodegradation was employed as a probe reaction to test the photocatalytic activity of the as-prepared samples under visible light irradiation. The photocatalytic activities of methyl orange degradation under visible light irradiation are strongly dependent on the pH used in the synthesis. The highest efficiency is observed at pH=7.展开更多
Ti3+-doped TiO2 nanosheets with tunable phase composition (doped TiO2 (A/R)) were synthesized via a hydrothermal method with high surface area anatase TiO2 nanosheets TiO2 (A) as a substrate, structure directin...Ti3+-doped TiO2 nanosheets with tunable phase composition (doped TiO2 (A/R)) were synthesized via a hydrothermal method with high surface area anatase TiO2 nanosheets TiO2 (A) as a substrate, structure directing agent, and inhibitor; the activity was evaluated using a probe reaction-photocatalytic CO2 conversion to methane under visible light irradiation with H2 as an electron donor and hydrogen source. High-resolution transmission electron microscope (HRTEM), field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, and X-ray diffraction (XRD) etc., were used to characterize the photocatalysts. XRD and HRTEM measurements confirmed the existence of anatase-rutile phase junction, while Ti3-and single-electron-trapped oxygen vacancy in the doped TiO2 (A/R) photocatalyst were revealed byelectron paramagnetic resonance (EPR) measurements. Effects of hydrothermal synthesis temperature and the amount of added anatase TiO2 on the photocatalytic activity were elucidated. Significantly enhanced photo- catalytic activity of doped TiO2 (A/R) was observed; under the optimized synthesis conditions, CH4 generation rate of doped TiO2 (A/R) was 2.3 times that of Ti3+-doped rutile TiO2.展开更多
A metal-free and environmentally friendly aerobic aromatization photosensitized by organic dye eosin Y bis(tetrabutyl ammonium salt)(TBA-eosinY)has been developed.With the aid of K_(2)CO_(3),the aerobic catalytic syst...A metal-free and environmentally friendly aerobic aromatization photosensitized by organic dye eosin Y bis(tetrabutyl ammonium salt)(TBA-eosinY)has been developed.With the aid of K_(2)CO_(3),the aerobic catalytic system converts 1,4-dihydropyridines to their corresponding pyridine derivatives efficiently under visible light irradiation(λ=450 nm)at room temperature.展开更多
Organic synthesis driven by heterogeneous catalysis is a central research theme to both fundamental research and industrial production of fine chemicals.However,the employment of stoichiometric strong oxidizing or red...Organic synthesis driven by heterogeneous catalysis is a central research theme to both fundamental research and industrial production of fine chemicals.However,the employment of stoichiometric strong oxidizing or reducing reagents(e.g.,K_(2)Cr_(2)O_(7) and LiAlH_(4))and harsh reaction conditions(e.g.,high temperature and pressure)always leads to the products of overreaction and other by-product residues(e.g.,salt and acid waste).Thus the poor control of product selectivity and tremendous energy consumption result in the urgent demand to develop novel technologies for heterogeneous catalysis.Given the current global theme of development in CO_(2) reduction and sustainable energy utilization,one promising protocol is heterogeneous photocatalysis.It enables sustainable solar-to-chemical energy conversion under mild conditions(e.g.,room temperature,ambient pressure,and air as the oxidant)and offers unique reaction pathways for improved selectivity control.To accurately tailor the selectivity of desired products,the electronic structure(e.g.,positions of valence-band maximum and conduction-band minimum),geometric structure(e.g.,nanorod,nanosheet,and porous morphology),and surface chemical micro-environment(e.g.,vacancy sites and co-catalysts)of heterogeneous photocatalysts require rational design and construction.In this review,we will briefly analyze some effective photocatalytic systems with the excellent regulation ability of product selectivity in organic transformations(mainly oxidation and reduction types)under visible light irradiation,and put forward opinions on the optimal fabrication of nanostructured photocatalysts to realize selective organic synthesis.展开更多
Gd-doped PbMoO_(4) nanoparticles were prepared by a refluxing method at 80℃ for 2 h.Effect of molar content of Gd dopant on phase,morphology and optical properties was studied.The as-prepared Gddoped PbMoO_(4) sample...Gd-doped PbMoO_(4) nanoparticles were prepared by a refluxing method at 80℃ for 2 h.Effect of molar content of Gd dopant on phase,morphology and optical properties was studied.The as-prepared Gddoped PbMoO_(4) samples can be indexed to pure tetragonal PbMoO_(4) phase.The particles size of PbMoO_(4) is decreased with increasing in the molar content of Gd dopant from 15.20±3.04 nm for pure PbMoO_(4) to 8.72±1.53 nm for 5 mol% Gd-doped PbMoO_(4).The absorption of 5 mol% Gd-doped PbMoO_(4) nanoparticles shows red-shift caused by lattice distortion of PbMoO_(4).The photocatalytic performance of 5 mol% Gddoped PbMoO_(4) nanoparticles shows the highest degradation of rhodamine B(RhB) of 97.92% under UV radiation and 67.65% under visible radiation because Gd^(3+) dopant as an electron acceptor plays the role in enhancing the separation of electron-hole pair.展开更多
A photoinduced reaction of potassium alkyltrifluoroborates,sulfur dioxide,and para-quinone methides under visible light irradiation at room temperature is developed,giving rise to diarylmethyl alkylsulfones in moderat...A photoinduced reaction of potassium alkyltrifluoroborates,sulfur dioxide,and para-quinone methides under visible light irradiation at room temperature is developed,giving rise to diarylmethyl alkylsulfones in moderate to good yields.This reaction works well under photocatalysis with a broad substrate scope by using DABCO·(SO_(2))_(2)as the source of sulfur dioxide.Mechanistic study shows that this transformation is initiated by alkyl radicals generated in situ from potassium alkyltrifluoroborates in the presence of photocatalyst.The subsequent insertion of sulfur dioxide and radical 1,6-addition of para-quinone methides with alkylsulfonyl radical intermediates afford the corresponding diarylmethyl alkylsulfones.展开更多
基金Project supported by the National Natural Science Foundation of China(No. 20567002)the Scientific Research Startup Foundation of InnerMongolia University (No. 203044)+2 种基金the Education Department of InnerMongolia Autonomous Region (No. NJ04093, NJ03121)the ChunhuiPlan of the Education Ministry (No. Z2004-2-15030)the "513 TalentsPlan" of Inner Mongolia University.
文摘The photocatalytic degradation of dye Rhodamine B (RhB) in the presence of TiO2 nanostdpe or P25 under visible light irradiation was investigated. The degradation intermediates were identified using Infrared spectra (IR spectra), ^1H nuclear magnetic resonance (^1HNMR) spectra, and gas chromatography-mass spectroscopy (GC-MS). The IR and the ^1HNMR results showed that the large conjugated chromophore structure of RhB was efficiently destroyed under visible light irradiation in both the photocatalytic systems (TiO2 nanostfipe or P25 and Rhodamine B systems). GC-MS results showed that the main identified intermediates were ethanediotic acid, 1,2-benzenedicarboxylic acid, 4-hydroxy benzoic acid and benzoic acid, which were almost the same in the TiO2 nanostdpes and P25 systems. This work provides a good insight into the reaction pathway(s) for the TiO2-assisted photocatalytic degradation of dye pollutants under visible light irradiation.
基金supported by the National Natural Science Foundation of China(No.21477050)the International Scientific and Technological Cooperation in Changzhou(No.CZ20140017)+2 种基金Postgraduate Research Innovation Project of Jiangsu Province(Nos.KYCX20_2561,KYCX20_2598)the Jiangsu Planned Projects for Postdoctoral Research Funds(No.2019K112)the Jiangsu Province subsidizes the recruitment of postdoctoral personnel(No.2019Z143)。
文摘Nonylphenol(NP)residues,as a typical endocrine disrupting chemical(EDC),frequently exist in sewage,surface water,groundwater and even drinking water,which poses a serious threat to human health due to its bioaccumulation.In order to remove NP,a series of MIL-100(Fe)/Zn Fe_(2)O_(4)/flake-like porous carbon nitride(MIL/ZC)was synthesized through in-situ synthesis at room temperature.High performance of ternary MIL/ZC is used to degrade NP under visible light irradiation.The results show that 30MIL/ZC2(20 wt.%Zn Fe_(2)O_(4))ternary composite had the best photocatalytic activity(99.84%)when the dosage was 30 mg.Further mechanism analysis shows that the excellent photocatalytic activity of 30MIL/ZC2could be ascribed to the double charge transfer process between flake-like porous carbon nitride(PCN)and other catalysts in the ternary heterojunction,and the separation of photogenerated electron-hole pairs was more effective.In addition,the 30MIL/ZC2 also showed high stability after five cycles of the photodegradation reaction.Furthermore,the active substance(·O_(2)^(-))was considered to be the main active substance in the NP degradation process.Based on the research results,the possible photocatalytic reaction mechanism of 30MIL/ZC2ternary composite was proposed and discussed in detail.
基金financial support provided by the National Natural Science Foundation of China(21676078)the Natural Science Foundation of Hunan Province for Distinguished Young Scholar(2016JJ1013)+1 种基金Scientific Research Fund of Hunan Provincial Education Department(19A323)Science and Technology Planning Project of Hunan Province(2018TP1017)。
文摘Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.
基金funded by the National Key Research and Development Program of China ( 2018YFB1501704)the National Natural Science Foundation of China (22078018)the Beijing Natural Science Foundation (2222016)。
文摘The selective oxidation of 5-hydroxymethylfurfural(HMF) into 2,5-diformylfuran(DFF) is an important reaction for renewable biomass building blocks. Compared with thermal catalytic processes, photocatalytic production of DFF from HMF has attracted tremendous attention. Herein, the MoS_(2)/CdIn_(2)S_(4)(MC)flower-like heterojunctions were prepared and considered as photocatalysts for selective oxidation of HMF into DFF under visible-light irradiation in aqueous solution. Results demonstrated MoS_(2) in MC heterojunction could promote the separation of photoexcited electron-hole pairs, while the amount of MoS_(2) dropping was proved influenced on the photocatalytic performance. 80.93% of DFF selectivity was realized when using 12.5% MC as photocatalyst. In addition, the MC catalyst also showed great potential in transformation of other biomass derived benzyl-and furyl-alcohols. The catalytic mechanism suggested that ·O_(2)^(-) was the decisive active radical for HMF oxidation. Therefore, the MC heterojunction could be applied in photocatalytic conversion of biomass to valuable chemicals under ambient condition.
基金financially supported by the National Natural Science Foundation of China(No.51574071)。
文摘Nanoflower-like ZnO-C_(3)N_(4) thin film with a porous net structure was successfully synthesized by a simple chemical corrosion method.The prepared ZnOC_(3)N_(4) thin films presented remarkable photocatalytic activities for the degradation of methyl orange under visible light irradiation,and more than 90%methyl orange was removed from water by ZnO-C_(3)N_(4) composite.Meanwhile,the ZnO-C_(3)N_(4) composite presented an enhanced photocatalytic stability.The loading content of C_(3)N_(4) had a great effect on the photocatalytic performance.Moreover,the photocatalytic activities were higher in acidic media than those in alkaline conditions.The adsorption of methyl orange was enhanced,and the recombination of photogenerated electrons and holes was suppressed with a suitable content of C_(3)N_(4).However,too much loading content of C_(3)N_(4) resulted in a poor dispersion of C_(3)N_(4) as the aggregated C_(3)N_(4) can behave as recombination centers.In addition,the prepared ZnO-C_(3)N_(4) thin film can be used for the water splitting in water-methanol system under simulated solar light irradiation.
基金financial supports from the Research Office of Amirkabir University of Technology (Tehran Polytechnic)
文摘Several nanoporous Fe2 O3-xSx/S-doped g-C3 N4(CNS) Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3 N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for guest molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe2 O3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe2 O3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe2 O3 and CNS components toward the photocatalytic degradation of methylene blue(MB). The optimal loaded Fe2 O3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min(-1) which was faster than those of the pure Fe2 O3(0.0016 min(-1))and CNS(0.0044 min(-1)) under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe2 O3(6.6)/CNS hybrid are 33.5 m2/g and0.195 cm3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe2 O3(6.6)/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured(at pH = 7) equal to-1.07 and 1.48 V versus normal hydrogen electrode(NHE), respectively.Trapping tests prove that ·OH-and ·O2-radicals are major active species in the photocatalytic reaction.It has been established that formation of the Z-scheme Fe2 O3(6.6)/CNS heterojunction between CNS and Fe2 O3 directly produces ·OH as well as ·O2-radicals which is consistent with the results obtained from trapping experiments.
基金Funded by the PCSIRT, the National Natural Science Foundation of China (Nos. 50532030 and 50625206)the Zhejiang Provincial Natural Science Foundation of China (No. Z4080021)
文摘Highly crystalline orthorhombic Bi2WO6 powders were hydrothermally synthesized from aqueous solutions of Na2WO4 · 2H2O and Bi (NO3)3 · 5H2O over a wide range of pH. The effect of pH on morphologies, sizes and properties of the Bi2WO6 crystals was investigated. The band gaps of the as-prepared Bi2WO6 were determined from the onset of the absorption edge of UV-vis diffuse reflectance spectra. The methyl orange photodegradation was employed as a probe reaction to test the photocatalytic activity of the as-prepared samples under visible light irradiation. The photocatalytic activities of methyl orange degradation under visible light irradiation are strongly dependent on the pH used in the synthesis. The highest efficiency is observed at pH=7.
文摘Ti3+-doped TiO2 nanosheets with tunable phase composition (doped TiO2 (A/R)) were synthesized via a hydrothermal method with high surface area anatase TiO2 nanosheets TiO2 (A) as a substrate, structure directing agent, and inhibitor; the activity was evaluated using a probe reaction-photocatalytic CO2 conversion to methane under visible light irradiation with H2 as an electron donor and hydrogen source. High-resolution transmission electron microscope (HRTEM), field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, and X-ray diffraction (XRD) etc., were used to characterize the photocatalysts. XRD and HRTEM measurements confirmed the existence of anatase-rutile phase junction, while Ti3-and single-electron-trapped oxygen vacancy in the doped TiO2 (A/R) photocatalyst were revealed byelectron paramagnetic resonance (EPR) measurements. Effects of hydrothermal synthesis temperature and the amount of added anatase TiO2 on the photocatalytic activity were elucidated. Significantly enhanced photo- catalytic activity of doped TiO2 (A/R) was observed; under the optimized synthesis conditions, CH4 generation rate of doped TiO2 (A/R) was 2.3 times that of Ti3+-doped rutile TiO2.
基金We are grateful for financial support from the National Natural Science Foundation of China(21172102)the Ministry of Science and Technology of China(2013CB834804)the Fundamental Research Funds for the Central Universities(lzujbky-2013-47).
文摘A metal-free and environmentally friendly aerobic aromatization photosensitized by organic dye eosin Y bis(tetrabutyl ammonium salt)(TBA-eosinY)has been developed.With the aid of K_(2)CO_(3),the aerobic catalytic system converts 1,4-dihydropyridines to their corresponding pyridine derivatives efficiently under visible light irradiation(λ=450 nm)at room temperature.
基金This work was supported by the National Key R&D Program of China(No.2020YFA0406103)the National Natural Science Foundation of China(NSFC)(Nos.21725102 and 91961106)+1 种基金the Dalian National Laboratory for Clean Energy(DNL)Cooperation Fund,Chinese Academy of Sciences(CAS)(No.DNL201922)the startup grant from University of Science and Technology of China(USTC)(No.KY2260080010).
文摘Organic synthesis driven by heterogeneous catalysis is a central research theme to both fundamental research and industrial production of fine chemicals.However,the employment of stoichiometric strong oxidizing or reducing reagents(e.g.,K_(2)Cr_(2)O_(7) and LiAlH_(4))and harsh reaction conditions(e.g.,high temperature and pressure)always leads to the products of overreaction and other by-product residues(e.g.,salt and acid waste).Thus the poor control of product selectivity and tremendous energy consumption result in the urgent demand to develop novel technologies for heterogeneous catalysis.Given the current global theme of development in CO_(2) reduction and sustainable energy utilization,one promising protocol is heterogeneous photocatalysis.It enables sustainable solar-to-chemical energy conversion under mild conditions(e.g.,room temperature,ambient pressure,and air as the oxidant)and offers unique reaction pathways for improved selectivity control.To accurately tailor the selectivity of desired products,the electronic structure(e.g.,positions of valence-band maximum and conduction-band minimum),geometric structure(e.g.,nanorod,nanosheet,and porous morphology),and surface chemical micro-environment(e.g.,vacancy sites and co-catalysts)of heterogeneous photocatalysts require rational design and construction.In this review,we will briefly analyze some effective photocatalytic systems with the excellent regulation ability of product selectivity in organic transformations(mainly oxidation and reduction types)under visible light irradiation,and put forward opinions on the optimal fabrication of nanostructured photocatalysts to realize selective organic synthesis.
基金supported by Center of Excellence in Materials Science and Technology,Chiang Mai University,Thailand。
文摘Gd-doped PbMoO_(4) nanoparticles were prepared by a refluxing method at 80℃ for 2 h.Effect of molar content of Gd dopant on phase,morphology and optical properties was studied.The as-prepared Gddoped PbMoO_(4) samples can be indexed to pure tetragonal PbMoO_(4) phase.The particles size of PbMoO_(4) is decreased with increasing in the molar content of Gd dopant from 15.20±3.04 nm for pure PbMoO_(4) to 8.72±1.53 nm for 5 mol% Gd-doped PbMoO_(4).The absorption of 5 mol% Gd-doped PbMoO_(4) nanoparticles shows red-shift caused by lattice distortion of PbMoO_(4).The photocatalytic performance of 5 mol% Gddoped PbMoO_(4) nanoparticles shows the highest degradation of rhodamine B(RhB) of 97.92% under UV radiation and 67.65% under visible radiation because Gd^(3+) dopant as an electron acceptor plays the role in enhancing the separation of electron-hole pair.
基金Financial support from the National Natural Science Foundation of China(Nos.22007017 and 21871053)the Talents'Startup Fund of Gannan Medical University(No.QD201831)+3 种基金the Education Bureau of Jiangxi Province(No.GJJ190799)the Research Fund of Gannan Medical University(No.ZD201905)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2019R01005)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(No.2020ZD04)。
文摘A photoinduced reaction of potassium alkyltrifluoroborates,sulfur dioxide,and para-quinone methides under visible light irradiation at room temperature is developed,giving rise to diarylmethyl alkylsulfones in moderate to good yields.This reaction works well under photocatalysis with a broad substrate scope by using DABCO·(SO_(2))_(2)as the source of sulfur dioxide.Mechanistic study shows that this transformation is initiated by alkyl radicals generated in situ from potassium alkyltrifluoroborates in the presence of photocatalyst.The subsequent insertion of sulfur dioxide and radical 1,6-addition of para-quinone methides with alkylsulfonyl radical intermediates afford the corresponding diarylmethyl alkylsulfones.