Herein,we established a Zn_(3)(OH)_(2)(V_(2)O_(7))(H_(2)O)_(2)/V-Zn(O,S)Z-scheme heterojunction labeled ZnVO/V-Zn(O,S)with a heterovalent V^(4+)/V^(5+)states and oxygen vacancies in both phases via a one-step in-situ ...Herein,we established a Zn_(3)(OH)_(2)(V_(2)O_(7))(H_(2)O)_(2)/V-Zn(O,S)Z-scheme heterojunction labeled ZnVO/V-Zn(O,S)with a heterovalent V^(4+)/V^(5+)states and oxygen vacancies in both phases via a one-step in-situ hydrolysis method.The NaBH_(4) regulated the ZnVO/V-Zn(O,S)-3 with rich Vo and suitable n(V^(4+))/n(V^(5+))ratio achieved an excellent photocatalytic nitrogen fixation activity of 301.7μmol/(g×h)and apparent quantum efficiency of 1.148%at 420 nm without any sacrificial agent,which is 11 times than that of V-Zn(O,S).The Vo acts as the active site to trap and activate N_(2) molecules and to trap and activate H_(2)O to produce the H for N_(2) molecules photocatalytic reduction.The rich Vo defects can also reduce the competitive adsorption of H_(2)O and N_(2) molecules on the surface active site of the catalyst.The heterovalent vanadium states act as the photogenerated electrons,quickly hopping between V^(4+)and V^(5+)to transfer for the photocatalytic N_(2) reduction reaction.Additionally,the Z-scheme heterojunction effectively minimizes photogenerated carrier recombination.These synergistic effects collectively boost the photocatalytic nitrogen fixation activity.This study provides a practical method for designing Z-scheme heterojunctions for efficient photocatalytic N_(2) fixation under mild conditions.展开更多
The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS...The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.展开更多
A heterojunction photoanode of Fe2O3 loaded on a WO3 film on a fluorine-doped tin oxide substrate(FTO-WO3/Fe2O3)was prepared via a simple hydrothermal and chemical vapor deposition(CVD)growth method.The photoanode sho...A heterojunction photoanode of Fe2O3 loaded on a WO3 film on a fluorine-doped tin oxide substrate(FTO-WO3/Fe2O3)was prepared via a simple hydrothermal and chemical vapor deposition(CVD)growth method.The photoanode showed higher photoelectrochemical(PEC)water-splitting activity than that of the pristine FTO-WO3 under simulated sunlight because of the synergistic effect of Fe2O3 and WO3.The as-synthesized material was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).The photocurrent density was estimated by linear sweep voltammetry and further confirmed using intensity-modulated photocurrent spectra.Experiments demonstrated that the coated Fe2O3 enhanced the separation and migration efficiencies of the photoinduced electrons and holes,improving the PEC water-splitting properties.The FTO-WO3/Fe2O3 photoanode showed a 1.25 times enhancement in photocurrent density compared with FTO-WO3.This result suggests that facile chemical vapor deposition growth is an effective way to fabricate heterojunctions and improve the properties of WO3 photoanodes for PEC water-splitting applications.展开更多
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
Constructing Z-scheme heterojunction to improve the separation efficiency of photogenerated carriers of photocatalysts has gained extensive attention.In this work,we fabricated a novel Z-scheme MoO3/Bi2O4 heterojuncti...Constructing Z-scheme heterojunction to improve the separation efficiency of photogenerated carriers of photocatalysts has gained extensive attention.In this work,we fabricated a novel Z-scheme MoO3/Bi2O4 heterojunction photocatalyst by a hydrothermal method.XPS analysis results indicated that strong interaction between MoO3 and Bi2O4 is generated,which contributes to charge transfer and separation of the photogenerated carriers.This was confirmed by photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)tests.The photocatalytic performance of the as-synthesized photocatalysts was evaluated by degrading rhodamine B(RhB)in aqueous solution under visible light irradiation,showing that 15%MoO3/Bi2O4(15-MB)composite exhibited the highest photocatalytic activity,which is 2 times higher than that of Bi2O4.Besides,the heterojunction photocatalyst can keep good photocatalytic activity and stability after five recycles.Trapping experiments demonstrated that the dominant active radicals in photocatalytic reactions are superoxide radical( O2-)and holes(h+),indicating that the 15-MB composite is a Z-scheme photocatalyst.Finally,the mechanism of the Z-scheme MoO3/Bi2O4 composite for photo-degrading RhB in aqueous solution is proposed.This work provides a promising strategy for designing Bi-based Z-scheme heterojunction photocatalysts for highly efficient removal of environmental pollutants.展开更多
Photocatalytic CO_(2)reduction to sustainably product of fuels is a potential route to achieve clean energy conversion.Unfortunately,the sluggish charge transport dynamics and poor CO_(2)activation performance result ...Photocatalytic CO_(2)reduction to sustainably product of fuels is a potential route to achieve clean energy conversion.Unfortunately,the sluggish charge transport dynamics and poor CO_(2)activation performance result in a low CO_(2)conversion efficiency.Herein,we develop a multidimensional In_(2)O_(3)/In_(2)S_(3)(IO/IS)heterojunction with abundant lattice distortion structure and high concentration of oxygen defects.The close contact interfaces between the junction of the two phases ensure undisturbed transmission of electrons with high‐speed.The increased free electron concentration promotes the adsorption and activation of CO2 on the catalyst surface,leaving the key intermediate*COOH at a lower energy barrier.The perfect combination of the band matching oxide and sulfide effectively reduces the internal energy barrier of the CO2 reduction reaction.Furthermore,the lattice distortion structure not only provides additional active sites,but also optimizes the kinetics of the reaction through microstructural regulation.Remarkably,the optimal IO/IS heterojunction exhibits superior CO_(2)reduction performance with CO evolution rate of 12.22μmol g^(−1)h^(−1),achieving about 4 times compared to that of In_(2)O_(3)and In2S3,respectively.This work emphasizes the importance of tight interfaces of heterojunction in improving the performance of CO_(2)photoreduction,and provides an effective strategy for construction of heterojunction photocatalysts.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
文摘Herein,we established a Zn_(3)(OH)_(2)(V_(2)O_(7))(H_(2)O)_(2)/V-Zn(O,S)Z-scheme heterojunction labeled ZnVO/V-Zn(O,S)with a heterovalent V^(4+)/V^(5+)states and oxygen vacancies in both phases via a one-step in-situ hydrolysis method.The NaBH_(4) regulated the ZnVO/V-Zn(O,S)-3 with rich Vo and suitable n(V^(4+))/n(V^(5+))ratio achieved an excellent photocatalytic nitrogen fixation activity of 301.7μmol/(g×h)and apparent quantum efficiency of 1.148%at 420 nm without any sacrificial agent,which is 11 times than that of V-Zn(O,S).The Vo acts as the active site to trap and activate N_(2) molecules and to trap and activate H_(2)O to produce the H for N_(2) molecules photocatalytic reduction.The rich Vo defects can also reduce the competitive adsorption of H_(2)O and N_(2) molecules on the surface active site of the catalyst.The heterovalent vanadium states act as the photogenerated electrons,quickly hopping between V^(4+)and V^(5+)to transfer for the photocatalytic N_(2) reduction reaction.Additionally,the Z-scheme heterojunction effectively minimizes photogenerated carrier recombination.These synergistic effects collectively boost the photocatalytic nitrogen fixation activity.This study provides a practical method for designing Z-scheme heterojunctions for efficient photocatalytic N_(2) fixation under mild conditions.
文摘The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.
基金financially supported by the National Natural Science Foundation of China(Nos.51672143 and 51808303)Shandong Province Natural Science Foundation(ZR2019BEE027,ZR2017MEM018,ZR2018BEM002)+2 种基金Taishan Scholars Program of Shandong ProvinceOutstanding Youth of Natural Science in Shandong Province(JQ201713)Australian Research Council Discovery Project(No.170103317)。
文摘A heterojunction photoanode of Fe2O3 loaded on a WO3 film on a fluorine-doped tin oxide substrate(FTO-WO3/Fe2O3)was prepared via a simple hydrothermal and chemical vapor deposition(CVD)growth method.The photoanode showed higher photoelectrochemical(PEC)water-splitting activity than that of the pristine FTO-WO3 under simulated sunlight because of the synergistic effect of Fe2O3 and WO3.The as-synthesized material was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).The photocurrent density was estimated by linear sweep voltammetry and further confirmed using intensity-modulated photocurrent spectra.Experiments demonstrated that the coated Fe2O3 enhanced the separation and migration efficiencies of the photoinduced electrons and holes,improving the PEC water-splitting properties.The FTO-WO3/Fe2O3 photoanode showed a 1.25 times enhancement in photocurrent density compared with FTO-WO3.This result suggests that facile chemical vapor deposition growth is an effective way to fabricate heterojunctions and improve the properties of WO3 photoanodes for PEC water-splitting applications.
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 Natural Science Foundation of Hubei Province(2016CFA078)the National Natural Science Foundation of China(51472194)~~
文摘Constructing Z-scheme heterojunction to improve the separation efficiency of photogenerated carriers of photocatalysts has gained extensive attention.In this work,we fabricated a novel Z-scheme MoO3/Bi2O4 heterojunction photocatalyst by a hydrothermal method.XPS analysis results indicated that strong interaction between MoO3 and Bi2O4 is generated,which contributes to charge transfer and separation of the photogenerated carriers.This was confirmed by photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)tests.The photocatalytic performance of the as-synthesized photocatalysts was evaluated by degrading rhodamine B(RhB)in aqueous solution under visible light irradiation,showing that 15%MoO3/Bi2O4(15-MB)composite exhibited the highest photocatalytic activity,which is 2 times higher than that of Bi2O4.Besides,the heterojunction photocatalyst can keep good photocatalytic activity and stability after five recycles.Trapping experiments demonstrated that the dominant active radicals in photocatalytic reactions are superoxide radical( O2-)and holes(h+),indicating that the 15-MB composite is a Z-scheme photocatalyst.Finally,the mechanism of the Z-scheme MoO3/Bi2O4 composite for photo-degrading RhB in aqueous solution is proposed.This work provides a promising strategy for designing Bi-based Z-scheme heterojunction photocatalysts for highly efficient removal of environmental pollutants.
文摘Photocatalytic CO_(2)reduction to sustainably product of fuels is a potential route to achieve clean energy conversion.Unfortunately,the sluggish charge transport dynamics and poor CO_(2)activation performance result in a low CO_(2)conversion efficiency.Herein,we develop a multidimensional In_(2)O_(3)/In_(2)S_(3)(IO/IS)heterojunction with abundant lattice distortion structure and high concentration of oxygen defects.The close contact interfaces between the junction of the two phases ensure undisturbed transmission of electrons with high‐speed.The increased free electron concentration promotes the adsorption and activation of CO2 on the catalyst surface,leaving the key intermediate*COOH at a lower energy barrier.The perfect combination of the band matching oxide and sulfide effectively reduces the internal energy barrier of the CO2 reduction reaction.Furthermore,the lattice distortion structure not only provides additional active sites,but also optimizes the kinetics of the reaction through microstructural regulation.Remarkably,the optimal IO/IS heterojunction exhibits superior CO_(2)reduction performance with CO evolution rate of 12.22μmol g^(−1)h^(−1),achieving about 4 times compared to that of In_(2)O_(3)and In2S3,respectively.This work emphasizes the importance of tight interfaces of heterojunction in improving the performance of CO_(2)photoreduction,and provides an effective strategy for construction of heterojunction photocatalysts.
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).
