长期以来,硫空位被认为是加氢脱硫的主要活性位,但关于S空位的位置及形成难易至今还存在一定的争议。为研究这一问题,本文从热力学和动力学的角度入手,对S空位形成过程进行详细的DFT计算。计算结果表明Mo边和S边产生S空位的过程均为吸...长期以来,硫空位被认为是加氢脱硫的主要活性位,但关于S空位的位置及形成难易至今还存在一定的争议。为研究这一问题,本文从热力学和动力学的角度入手,对S空位形成过程进行详细的DFT计算。计算结果表明Mo边和S边产生S空位的过程均为吸热反应。但Mo边产生空位受热力学限制严重,在高温、低H2S浓度下才能产生S空位。在通常加氢脱硫条件下S空位主要存在于S边,S边产生S空位的过程中最高能垒约为147 k J/mol。展开更多
Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme hetero...Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies(VO,Zn-ZnO/ZnS)is rationally constructed via ion-exchange and calcination treatments.In such a photocatalytic system,the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption.Moreover,the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes,respectively,which are beneficial for promoting the photo-induced carrier separation.Meanwhile,the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity.As expected,the optimized VO,Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H_(2) production rate of 160.91 mmol g^(-1)h^(-1),approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS,respectively.Simultaneously,the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S-scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier.This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar-to-fuel energy conversion.展开更多
To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve...To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging.In this work,a well-designed nanosheet-based rodlike step-scheme(S-scheme)heterojunction Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with rich oxygen vacancies(OVs)(Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2)-OV)was easily synthesized by calcining BiOAc0.6Br0.2I0.2(Ac-=CH3 COO-)precursor.The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline(TC)and dye rhodamine B(Rh B)degradation and removal rate reached 90.2% and 97.0%within 120 min,respectively,which was higher than those of Bi4O5I2-OV(56.8% and 71.8%),Bi4O5Br2-OV(47.4%and 68.4%),solid solution BiOAc0.6Br0.2I0.2(67.0% and 84.0%)and Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with poor oxygen vacancies(Bi4O5I2/Bi4O5Br2-P)(30.6%and 40.4%).Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac-,it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides,which thus decreased particle size and increased surface areas,but also introduce surface OVs,which could trap photoelectrons and inhibit the recombination of carriers.In addition,the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials,which facilitates charge carriers transfer at the interfaces.The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and Rh B in actual wastewater or in the presence of some electrolytes.This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.展开更多
Enlightened by natural photosynthesis,developing efficient S-scheme heterojunction photocatalysts for deleterious pollutant removal is of prime importance to restore environment.Herein,novel TaON/Bi_(2)WO_(6) S-scheme...Enlightened by natural photosynthesis,developing efficient S-scheme heterojunction photocatalysts for deleterious pollutant removal is of prime importance to restore environment.Herein,novel TaON/Bi_(2)WO_(6) S-scheme heterojunction nanofibers were designed and developed by in-situ growing Bi_(2)WO_(6) nanosheets with oxygen vacancies(OVs)on TaON nanofibers.Thanks to the efficiently spatial charge disassociation and preserved great redox power by the unique S-scheme mechanism and OVs,as well as firmly interfacial contact by the core-shell 1D/2D fibrous hetero-structure via the in-situ growth,the optimized TaON/Bi_(2)WO_(6) heterojunction unveils exceptional visible-light photocatalytic property for abatement of tetracycline(TC),levofloxacin(LEV),and Cr(Ⅵ),respectively by 2.8-fold,1.0-fold,and 1.9-fold enhancement compared to the bare Bi_(2)WO_(6),while maintaining satisfactory stability.Furthermore,the systematic photoreaction tests indicate Ta-ON/Bi_(2)WO_(6) has the high practicality in the elimination of pollutants in aquatic environment.The degradation pathway of tetracycline and intermediate eco-toxicity were determined based on HPLC–MS combined with QSAR calculation,and a possible photocatalytic mechanism was elucidated.This work provides a guideline for designing high-performance TaON-based S-scheme photocatalysts with defects for environment protection.展开更多
This paper deals with the pointwise multipliers from space F（p, q, s） to space βα on the unit ball B of C^n. The multiplier spaces M（F（p, q, s）,βα） are fully characterized.
文摘长期以来,硫空位被认为是加氢脱硫的主要活性位,但关于S空位的位置及形成难易至今还存在一定的争议。为研究这一问题,本文从热力学和动力学的角度入手,对S空位形成过程进行详细的DFT计算。计算结果表明Mo边和S边产生S空位的过程均为吸热反应。但Mo边产生空位受热力学限制严重,在高温、低H2S浓度下才能产生S空位。在通常加氢脱硫条件下S空位主要存在于S边,S边产生S空位的过程中最高能垒约为147 k J/mol。
文摘Designing a step-scheme(S-scheme)heterojunction photocatalyst with vacancy engineering is a reliable approach to achieve highly efficient photocatalytic H_(2)production activity.Herein,a hollow ZnO/ZnS S-scheme heterojunction with O and Zn vacancies(VO,Zn-ZnO/ZnS)is rationally constructed via ion-exchange and calcination treatments.In such a photocatalytic system,the hollow structure combined with the introduction of dual vacancies endows the adequate light absorption.Moreover,the O and Zn vacancies serve as the trapping sites for photo-induced electrons and holes,respectively,which are beneficial for promoting the photo-induced carrier separation.Meanwhile,the S-scheme charge transfer mechanism can not only improve the separation and transfer efficiencies of photo-induced carrier but also retain the strong redox capacity.As expected,the optimized VO,Zn-ZnO/ZnS heterojunction exhibits a superior photocatalytic H_(2) production rate of 160.91 mmol g^(-1)h^(-1),approximately 643.6 times and 214.5 times with respect to that obtained on pure ZnO and ZnS,respectively.Simultaneously,the experimental results and density functional theory calculations disclose that the photo-induced carrier transfer pathway follows the S-scheme heterojunction mechanism and the introduction of O and Zn vacancies reduces the surface reaction barrier.This work provides an innovative strategy of vacancy engineering in S-scheme heterojunction for solar-to-fuel energy conversion.
文摘To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging.In this work,a well-designed nanosheet-based rodlike step-scheme(S-scheme)heterojunction Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with rich oxygen vacancies(OVs)(Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2)-OV)was easily synthesized by calcining BiOAc0.6Br0.2I0.2(Ac-=CH3 COO-)precursor.The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline(TC)and dye rhodamine B(Rh B)degradation and removal rate reached 90.2% and 97.0%within 120 min,respectively,which was higher than those of Bi4O5I2-OV(56.8% and 71.8%),Bi4O5Br2-OV(47.4%and 68.4%),solid solution BiOAc0.6Br0.2I0.2(67.0% and 84.0%)and Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with poor oxygen vacancies(Bi4O5I2/Bi4O5Br2-P)(30.6%and 40.4%).Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac-,it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides,which thus decreased particle size and increased surface areas,but also introduce surface OVs,which could trap photoelectrons and inhibit the recombination of carriers.In addition,the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials,which facilitates charge carriers transfer at the interfaces.The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and Rh B in actual wastewater or in the presence of some electrolytes.This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.
文摘Enlightened by natural photosynthesis,developing efficient S-scheme heterojunction photocatalysts for deleterious pollutant removal is of prime importance to restore environment.Herein,novel TaON/Bi_(2)WO_(6) S-scheme heterojunction nanofibers were designed and developed by in-situ growing Bi_(2)WO_(6) nanosheets with oxygen vacancies(OVs)on TaON nanofibers.Thanks to the efficiently spatial charge disassociation and preserved great redox power by the unique S-scheme mechanism and OVs,as well as firmly interfacial contact by the core-shell 1D/2D fibrous hetero-structure via the in-situ growth,the optimized TaON/Bi_(2)WO_(6) heterojunction unveils exceptional visible-light photocatalytic property for abatement of tetracycline(TC),levofloxacin(LEV),and Cr(Ⅵ),respectively by 2.8-fold,1.0-fold,and 1.9-fold enhancement compared to the bare Bi_(2)WO_(6),while maintaining satisfactory stability.Furthermore,the systematic photoreaction tests indicate Ta-ON/Bi_(2)WO_(6) has the high practicality in the elimination of pollutants in aquatic environment.The degradation pathway of tetracycline and intermediate eco-toxicity were determined based on HPLC–MS combined with QSAR calculation,and a possible photocatalytic mechanism was elucidated.This work provides a guideline for designing high-performance TaON-based S-scheme photocatalysts with defects for environment protection.
基金the National Natural Science Foundation of China(19871026).
文摘This paper deals with the pointwise multipliers from space F（p, q, s） to space βα on the unit ball B of C^n. The multiplier spaces M（F（p, q, s）,βα） are fully characterized.
