Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON n...Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON nanoparticles are synthesized via heating a vacuum-sealed mixture of KTaO_(3),Ta and NH_(4)Cl.This method possesses multiple advantages in terms of lower calcination parameter,higher N conversion efficiency and superior photocatalytic activity in comparison with the traditional thermal ammonolysis using NH_(3) gas as a nitrogen source.Through the analysis of intermediates produced upon the elevation of heating temperature,a gas-solid-phase reaction between TaCl_(5) and Ta_(2)O_(5) is demonstrated as the final step,which is conducive to decreasing thermal energy barrier and accelerating nitridation process.Precise control of preparation conditions,including calcination temperature and duration,allows for the regulation of surface O/N ratio of TaON particles to unity,resulting in optimized photocat-alytic activity.Photoelectrochemical assessment and intensity modulated photocurrent spectroscopy provide convincing evidence for improved charge transfer effciency of photoexcited holes at TaON surface.A Z-scheme overall water splitting is accomplished by employing the TaON as an effective oxygen evolution photocatalyst,SrTiO_(3):Rh as a hydrogen evolution photocatalyst,and reduced graphene oxide(rGO)as a solid-state electron mediator.This work presents a promising strategy for the synthesis of high-quality oxynitride materials in application to photocatalytic water splitting.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
Efficient and stable photoelectrodes for water oxidation are highly desirable in the field of photoelectrochemical(PEC)water splitting.However,photoelectrodes with low externally applied bias usually exhibit weak phot...Efficient and stable photoelectrodes for water oxidation are highly desirable in the field of photoelectrochemical(PEC)water splitting.However,photoelectrodes with low externally applied bias usually exhibit weak photocurrent and vice versa.Herein,novel and efficient CoO_(x)-TaON/LTON composite photoanodes have been successfully prepared by a microwave assisted method followed with a particle transfer procedure.The obtained photoanode generated an anodic photocurrent of∼7.2 mA cm^(−2) at 1.2 V_(RHE) and initiated the anodic photourrent at∼0.5 V_(RHE).The HC-STH of the composite photoelectrode reached 1.0%at 1.2 V_(RHE).Further,stoichiometric oxygen and hydrogen are stably produced on the photoanode and the counter electrode with a Faraday efficiency of unity for 2 h.展开更多
Pyrolysis of the Ta_(2)_(O5)/melamine mixture in molten chlorides is herein demonstrated as a facile and controllable method to nitridize and functionalize Ta_(2)_(O5).The influence of the stoichiometry and compositio...Pyrolysis of the Ta_(2)_(O5)/melamine mixture in molten chlorides is herein demonstrated as a facile and controllable method to nitridize and functionalize Ta_(2)_(O5).The influence of the stoichiometry and composition of Ta_(2)_(O5)/melamine in molten salts on the nitridation process is rationalized to ensure the controllable preparation of Ta_(3)N_(5) and Ta_(3)N_(5)/TaON.The characterization results,including scanning electron microscopy,transmission electron microscopy,elemental mapping,X-ray photoelectron spectroscopy,and photoluminescence spectroscopy,all confirm the existence of the Ta_(3)N_(5)/TaON heterojunction,in which the TaON nanoparticles are closely anchored to the Ta_(3)N_(5) nanorods.Benefiting from its composition and structure,the Ta_(3)N_(5)/TaON composites show enhanced photocatalytic activity for the degradation of methylene blue.The present study highlights that the molten salt method using a solid nitrogen source can be a new technique for rationalizing the design of nitrides and oxynitrides.展开更多
The effects of different NH3-plasma treatment procedures on interracial and electrical properties of Ge MOS capacitors with stacked gate dielectric of HtTiON/TaON were investigated. The NH3-plasma treatment was perfor...The effects of different NH3-plasma treatment procedures on interracial and electrical properties of Ge MOS capacitors with stacked gate dielectric of HtTiON/TaON were investigated. The NH3-plasma treatment was performed at different steps during fabrication of the stacked gate dielectric, i.e. before or after interlayer （TaON） deposition, or after deposition ofhigh-k dielectric （HfriON）. It was found that the excellent interface quality with an interface-state density of 4.79 × 101l eV-lcm-2 and low gate leakage current （3.43 ×10-5 A/cm2 at Vg = 1 V） could be achieved for the sample with NH3-plasma treatment directly on the Ge surface before TaON deposition. The involved mechanisms are attributed to the fact that the NH3-plasma can directly react with the Ge surface to form more Ge-N bonds, i.e. more GeOxNy, which effectively blocks the inter-diffusion of elements and suppresses the formation of unstable GeOx interfacial layer, and also passivates oxygen vacancies and dangling bonds near/at the interface due to more N incorporation and decomposed H atoms from the NH3-plasma.展开更多
基金supported by the Starting Foundation of ShanghaiTech Universitythe Double First-Class Initiative Fund of ShanghaiTech Universitythe National Natural Science Foundation of China (21972092)
文摘Oxynitride semiconductors are promising photocatalyst materials for visible light-driven water splitting,while the synthesis of well crystalized oxynitride still remains challenge.In present work,narrow-bandgap TaON nanoparticles are synthesized via heating a vacuum-sealed mixture of KTaO_(3),Ta and NH_(4)Cl.This method possesses multiple advantages in terms of lower calcination parameter,higher N conversion efficiency and superior photocatalytic activity in comparison with the traditional thermal ammonolysis using NH_(3) gas as a nitrogen source.Through the analysis of intermediates produced upon the elevation of heating temperature,a gas-solid-phase reaction between TaCl_(5) and Ta_(2)O_(5) is demonstrated as the final step,which is conducive to decreasing thermal energy barrier and accelerating nitridation process.Precise control of preparation conditions,including calcination temperature and duration,allows for the regulation of surface O/N ratio of TaON particles to unity,resulting in optimized photocat-alytic activity.Photoelectrochemical assessment and intensity modulated photocurrent spectroscopy provide convincing evidence for improved charge transfer effciency of photoexcited holes at TaON surface.A Z-scheme overall water splitting is accomplished by employing the TaON as an effective oxygen evolution photocatalyst,SrTiO_(3):Rh as a hydrogen evolution photocatalyst,and reduced graphene oxide(rGO)as a solid-state electron mediator.This work presents a promising strategy for the synthesis of high-quality oxynitride materials in application to photocatalytic water splitting.
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 Natural Science Foundation of China(Grant No.21872174 and U1932148)Project of Innovation-Driven Plan in Central South University(Grant No.20180018050001)+3 种基金State Key Laboratory of Powder Metallurgy,International Science and Technology Cooperation Program(Grant No.2017YFE0127800)Hunan Provincial Science and Technology Program Youth Talents Plan of China and Hundred Youth Talents Program of Hunan.(2017XK2026)Shenzhen Science and Technology Innovation Project(Grant No.JCYJ20180307151313532)Thousand Youth Talents Plan of China and Hundred Youth Talents Program of Hunan.
文摘Efficient and stable photoelectrodes for water oxidation are highly desirable in the field of photoelectrochemical(PEC)water splitting.However,photoelectrodes with low externally applied bias usually exhibit weak photocurrent and vice versa.Herein,novel and efficient CoO_(x)-TaON/LTON composite photoanodes have been successfully prepared by a microwave assisted method followed with a particle transfer procedure.The obtained photoanode generated an anodic photocurrent of∼7.2 mA cm^(−2) at 1.2 V_(RHE) and initiated the anodic photourrent at∼0.5 V_(RHE).The HC-STH of the composite photoelectrode reached 1.0%at 1.2 V_(RHE).Further,stoichiometric oxygen and hydrogen are stably produced on the photoanode and the counter electrode with a Faraday efficiency of unity for 2 h.
基金the National Natural Science Foundation of China(Nos.51722404,51674177,51804221,and 91845113)the National Key R&D Program of China(No.2018YFE0201703)+2 种基金the China Postdoctoral Science Foundation(Nos.2018M642906 and 2019T120684)the Fundamental Research Funds for the Central Universities(No.2042019kf0230)the Hubei Provincial Natural Science Foundation of China(No.2019CFA065)。
文摘Pyrolysis of the Ta_(2)_(O5)/melamine mixture in molten chlorides is herein demonstrated as a facile and controllable method to nitridize and functionalize Ta_(2)_(O5).The influence of the stoichiometry and composition of Ta_(2)_(O5)/melamine in molten salts on the nitridation process is rationalized to ensure the controllable preparation of Ta_(3)N_(5) and Ta_(3)N_(5)/TaON.The characterization results,including scanning electron microscopy,transmission electron microscopy,elemental mapping,X-ray photoelectron spectroscopy,and photoluminescence spectroscopy,all confirm the existence of the Ta_(3)N_(5)/TaON heterojunction,in which the TaON nanoparticles are closely anchored to the Ta_(3)N_(5) nanorods.Benefiting from its composition and structure,the Ta_(3)N_(5)/TaON composites show enhanced photocatalytic activity for the degradation of methylene blue.The present study highlights that the molten salt method using a solid nitrogen source can be a new technique for rationalizing the design of nitrides and oxynitrides.
基金supported by the National Natural Science Foundation of China(Nos.61176100,61274112)
文摘The effects of different NH3-plasma treatment procedures on interracial and electrical properties of Ge MOS capacitors with stacked gate dielectric of HtTiON/TaON were investigated. The NH3-plasma treatment was performed at different steps during fabrication of the stacked gate dielectric, i.e. before or after interlayer （TaON） deposition, or after deposition ofhigh-k dielectric （HfriON）. It was found that the excellent interface quality with an interface-state density of 4.79 × 101l eV-lcm-2 and low gate leakage current （3.43 ×10-5 A/cm2 at Vg = 1 V） could be achieved for the sample with NH3-plasma treatment directly on the Ge surface before TaON deposition. The involved mechanisms are attributed to the fact that the NH3-plasma can directly react with the Ge surface to form more Ge-N bonds, i.e. more GeOxNy, which effectively blocks the inter-diffusion of elements and suppresses the formation of unstable GeOx interfacial layer, and also passivates oxygen vacancies and dangling bonds near/at the interface due to more N incorporation and decomposed H atoms from the NH3-plasma.
