Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-sc...Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.展开更多
A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigate...A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.展开更多
Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction bet...Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).展开更多
Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural ch...Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural characterization demonstrated that the TiO2 nanowires were uniformly coated by the singlecrystal SrTiO3 shell,where continuous and large-area interface could be clearly observed.By this means,significantly enhanced photoelectrochemical water splitting properties(0.78 mA·cm^-2 at 1.23 V vs.RHE)were successfully realized in well-designed sample(with a shell thickness of 5–10 nm)compared with those of pristine TiO2(0.38 mA·cm^-2 at 1.23 V vs.RHE).The improvement of photoelectrochemical properties was attributed to the improved charge injection and charge separation,which are calculated by the results of water oxidation and sulfite oxidation measurements.Based on these results,a mechanism was proposed that SrTiO3 shell acted as an electron–hole separation layer to improve the photocurrent density.On the other hand,the sample with an over-thick SrTiO3 shell(20–40 nm)exhibited slightly reduced photoelectrochemical properties(0.66 mA·cm^-2),which could be explained by the increase of the recombination rate in thethicker SrTiO3 shell.This work provided a facile strategy to improve and modulate the photoelectrochemical performance of heterostructured photoanodes.展开更多
A series of TiO2/Bi2O3 heterojunction microfibers have been fabricated using cotton fibers as bio-templates, and characterized by XRD, SEM and UV-Vis techniques. Results reveal that Bi2O3 in the TiO2/Bi2O3 sample is a...A series of TiO2/Bi2O3 heterojunction microfibers have been fabricated using cotton fibers as bio-templates, and characterized by XRD, SEM and UV-Vis techniques. Results reveal that Bi2O3 in the TiO2/Bi2O3 sample is assigned to monoclinic and tetragonal mix-crystal phase. Fibers lengths can reach several micrometers and diameters range from 0.5 μm to 3 μm. Compared with pure TiO2 and Bi2O3, TiO2/Bi2O3 samples display better absorption in visible light region. Photocatalytic activity was evaluated by degradation of MB under visible light irradiation. TiO2/Bi2O3 microfibers exhibite much higher activity than pure TiO2 and Bi2O3, and 22.84%TiO2/Bi2O3 can achieve the decomposition of about 95%MB, which is attributed to synergistic effects of the strong visible-light absorption of TiO2/Bi2O3 microfibers and the heterojunction formed between TiO2 and Bi2O3.展开更多
文摘Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.
基金supported by the Scientific Research Project from Hubei Provincial Department of Education(Q20181808)the Research and Innovation Initiatives of Wuhan Polytechnic University(2018J04,2018Y07)~~
文摘A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.
基金supported by the National Natural Science Foundation of China(Nos.51822202 and 51772050)China Postdoctoral Science Foundation(No.2019M651342)+2 种基金Shanghai Rising-Star Program(No.18QA1400100)Youth Top-notch Talent Support Program of Shanghai,the Shanghai Committee of Science and Technology,China(No.19520713200)DHU Distinguished Young Professor Program and Fundamental Research Funds for the Central Universities。
文摘Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).
基金financially supported by the National Natural Science Foundation of China (Nos. 51232006, 51472218 and 11474249)the National Basic Research Program of China (No. 2015CB654900)
文摘Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural characterization demonstrated that the TiO2 nanowires were uniformly coated by the singlecrystal SrTiO3 shell,where continuous and large-area interface could be clearly observed.By this means,significantly enhanced photoelectrochemical water splitting properties(0.78 mA·cm^-2 at 1.23 V vs.RHE)were successfully realized in well-designed sample(with a shell thickness of 5–10 nm)compared with those of pristine TiO2(0.38 mA·cm^-2 at 1.23 V vs.RHE).The improvement of photoelectrochemical properties was attributed to the improved charge injection and charge separation,which are calculated by the results of water oxidation and sulfite oxidation measurements.Based on these results,a mechanism was proposed that SrTiO3 shell acted as an electron–hole separation layer to improve the photocurrent density.On the other hand,the sample with an over-thick SrTiO3 shell(20–40 nm)exhibited slightly reduced photoelectrochemical properties(0.66 mA·cm^-2),which could be explained by the increase of the recombination rate in thethicker SrTiO3 shell.This work provided a facile strategy to improve and modulate the photoelectrochemical performance of heterostructured photoanodes.
基金V. ACKNOWLEDGEMENTS This work was supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department （No.2013JK0690）, and the Shaanxi Province Natural Science Foundation （No.2013JM2013）, the National Natural Science Foundation of China （No.21203160）, and the Special Research Fund of Xianyang Normal University （No. 11XSYK204）.
文摘A series of TiO2/Bi2O3 heterojunction microfibers have been fabricated using cotton fibers as bio-templates, and characterized by XRD, SEM and UV-Vis techniques. Results reveal that Bi2O3 in the TiO2/Bi2O3 sample is assigned to monoclinic and tetragonal mix-crystal phase. Fibers lengths can reach several micrometers and diameters range from 0.5 μm to 3 μm. Compared with pure TiO2 and Bi2O3, TiO2/Bi2O3 samples display better absorption in visible light region. Photocatalytic activity was evaluated by degradation of MB under visible light irradiation. TiO2/Bi2O3 microfibers exhibite much higher activity than pure TiO2 and Bi2O3, and 22.84%TiO2/Bi2O3 can achieve the decomposition of about 95%MB, which is attributed to synergistic effects of the strong visible-light absorption of TiO2/Bi2O3 microfibers and the heterojunction formed between TiO2 and Bi2O3.
