The development of ZnO-based composites with high charge separation and effective inhibition of toxic by-products is admirable for effective photocatalysis of nitrogen oxides(NO_(x))oxidation.In this study,carbon quan...The development of ZnO-based composites with high charge separation and effective inhibition of toxic by-products is admirable for effective photocatalysis of nitrogen oxides(NO_(x))oxidation.In this study,carbon quan-tum dots(CQDs)/ZnO hollow microspheres,synthesized through a rapid microwave-assisted method,achievedover a 30-fold higher NO_(x) removal efficiency compared to ZnO,with complete inhibition of NO_(2) by-products andgood durability.The enhanced photocatalytic activity was ascribed to the unique role of CQDs,as revealed byin-situ photoelectric techniques.Results demonstrated that the electron directional migration from ZnO to CQDsat the composite interface accounts for the enhanced charge separation.Active free radicals for NO_(x) oxidationwere identified,and in-situ diffuse reflectance infrared Fourier transform spectroscopy analysis elucidated theconversion pathways of NO_(x) oxidation under visible light irradiation.This work sheds light on the mechanismsof electron transfer and charge separation at the composite interface,offering guidance for designing superiorZnO-based photocatalysts for complete NO_(x) removal.展开更多
The linker defect engineering for MOFs is a viable strategy that usually can effectively augment conductivity to further promote charge carrier separation,which is the most excellent conductivity of preserved metal cl...The linker defect engineering for MOFs is a viable strategy that usually can effectively augment conductivity to further promote charge carrier separation,which is the most excellent conductivity of preserved metal clusters.However,the partially missing photosensitive linker often leads to the diminished light utilization efficiency.As we know,in the linker defect engineering,addressing the lack of photosensitivity while maintaining outstanding conductivity is still in its infancy.In this essay,the linkerdefective NH_(2)-MIL-125 was obtained by adding the glacial acetic acid regulator,subsequently,the excellent light-responsive Pt/CQDs with up-conversion effect was in-situ encapsulated into the enlarged pore space of linker-defective NH_(2)-MIL-125.It is excited that the fabricated dual-functional composite ideally integrates photosensitivity and conductivity for photocatalytic hydrogen evolution and NO elimination.The optimal Pt/CQDs@NM-125-4 exhibited very superior photocatalytic hydrogen evolution(28.75mmol/g),it was 11.63 times as that of the initial NH_(2)-MIL-125(2.47 mmol/g)and 1.4 times as that of the defective NM-125-4(20.46 mmol/g).In addition,the excellent photocatalytic NO removal efficiency was 52.12%for Pt/CQDs@NM-125-4,whereas the original NH_(2)-MIL-125 only reached 30%and the defective NM-125-4 achieved 44.96%.The corresponding optical and electrical characterization based on UV-vis,up-conversion photoluminescence(UCPL),and electrochemical impedance spectroscopy(EIS)etc.demonstrated the defect engineering accelerates the charge carriers transfer via enhancing conductivity,and the in-situ confined up-conversion Pt/CQDs promote the visible light response.Our work presents a feasible avenue to integrate photosensitivity and conductivity via in-situ fabricating excellent lightresponsive Pt/CQDs within linker-defective NH_(2)-MIL-125 for further significantly boosting photocatalytic performance.展开更多
The endocrine-disrupting chemicals(EDCs)and antibiotics are causing negative effects on human beings and animals by disrupting the endocrine system and spreading antimicrobial resistance.The current need is to eradica...The endocrine-disrupting chemicals(EDCs)and antibiotics are causing negative effects on human beings and animals by disrupting the endocrine system and spreading antimicrobial resistance.The current need is to eradicate pharmaceutical waste from water bodies using advanced catalytic systems with high efficiency.Novel ternary carbon quantum dots(CQDs)decorated Z-Scheme WS_(2)-PANI nanocomposite was prepared by a green synthesis assisted in-situ polymerization for the photodegradation and detection of Estradiol(EST)and Nitrofurantoin(NFT).HRTEM micrographs revealed the formation of CQDs with a mean size of 4nm anchored on the surface of WS_(2)/PANI(width:PANI~20-30nm).The ternary nanocomposite showed excellent photocatalytic activity,degraded NFT(95.7%in 60min),and EST(96.6%in 60min).The rate kinetics study confirms the reaction followed pseudo first-order model.This heterostructure exhibited enhanced performances by modulating the energy level configuration,enhancing the absorption of visible light(2.4eV),and significantly improving the charge separation,three times higher than pristine WS_(2).These are highly favorable for increasing the generation of photoinduced charges and enhancing the overall performance of the catalyst.Further,the electrochemical sensor was prepared using CQDs@WS_(2)/PANI nanocomposite on a paper-based electrode.The CQDs@WS_(2)/PANI exhibit a linear response of 0.1-100nM,with a limit of detection of 13nM.This synergistic interfacial interaction resulted in the significantly improved electrochemical performance of the modified electrode.The proposed Z-scheme was justified by electron paramagnetic resonance(EPR)and scavenger experiment.An intermediate degradation pathway was also proposed.The synthesized materials were characterized using FESEM,HRTEM,XRD,FTIR,XPS,UV-visible spectroscopy,PL,and TRPL.Therefore,this study provides a direct approach to fabricate a heterojunction that combines two-dimensional,one dimensional,and zero-dimensional properties,enabling control over the energy level configuration and subsequent improvements in photocatalytic and electrocatalytic efficiency.展开更多
NH_(2)-MIL-125 and its derivatives are receivingmore attention in various aspects of photocatalytic reactions,especially in the photocatalytic hydrogen peroxide(H_(2)O_(2))production from water(H_(2)O)and oxygen(O_(2)...NH_(2)-MIL-125 and its derivatives are receivingmore attention in various aspects of photocatalytic reactions,especially in the photocatalytic hydrogen peroxide(H_(2)O_(2))production from water(H_(2)O)and oxygen(O_(2)),which is a promising and sustainable strategy.However,the generation of H_(2)O_(2) from NH_(2)-MIL-125 is far from satisfactory due to rapid photo-generated carriers recombination and poor surface electron transfer.In the work,the composite photocatalyst CQDs/TiO_(2)/NH_(2)-MIL-125(C/T/NM)was designed for the first time by one-step hydrothermal method.TiO_(2) was in situ converted from partial NH_(2)-MIL-125(NM)during the successful loaded of Carbon quantum dots(CQDs)by hydrothermal process.The results indicated the typeⅡheterojunction was successfully constructed between the NM and TiO_(2) interface,which could promote the transmission of photo-generated electrons.In addition,the successful loaded of CQDs could effectively transfer and stored the photo-generated electrons to the photocatalyst surface to participate in the reaction,and further avoiding the recombination of photo-generated carriers.The C/T/NM composite photocatalyst achieved a H_(2)O_(2) generation of 455μmol/L for 5 hours under visible light without oxygen bubbling,whichwas 7.1 times superior to that of NM.The H_(2)O_(2) generation rate reached 645.4μM/(g·h),which was in priority in the reported literature under the same conditions.Finally,based on the active species capture experiments,energy band structure analysis and the photoelectrochemicalmeasurements,a possiblemechanism for the efficientH_(2)O_(2) generation through C/T/NM had been proposed.This work provided new ideas for designing NH_(2)-MIL-125 based composite photocatalysts for the production of H_(2)O_(2).展开更多
The development of highly active and stable bifunctional electrocatalysts in acidic media is crucial to hydrogen production by proton exchange membrane.In this study,we designed a RuO_(2)-IrO_(2)heterostructure cataly...The development of highly active and stable bifunctional electrocatalysts in acidic media is crucial to hydrogen production by proton exchange membrane.In this study,we designed a RuO_(2)-IrO_(2)heterostructure catalyst coupled by carbon quantum dots(CQDs).The catalyst showed excellent electrocatalytic performance for water splitting under acidic conditions.The overpotentials of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)were as low as 180 and 15 mV at 10 mA/cm^(2)in 0.5 M H_(2)SO_(4),respectively.The acid electrolytic cell developed with RuO_(2)-IrO_(2)@CQDs as anode and cathode operated stably at 10 m A/cm^(2)for 120 h.In situ measurements and theoretical calculation reveal that the unique lattice oxygen mechanism path of RuO_(2)-IrO_(2)@CQDs can bypass the OOH^(*)intermediate and breaks the linear relationship of adsorbent evolution mechanism path,resulting in higher OER catalytic activity.展开更多
The development of efficient and stable visible-light-driven hydrogen(H_(2))generation photocatalysts plays a crucial role in sustainable energy conversion.In this study,we constructed an all-solid Z-scheme heterostru...The development of efficient and stable visible-light-driven hydrogen(H_(2))generation photocatalysts plays a crucial role in sustainable energy conversion.In this study,we constructed an all-solid Z-scheme heterostructure by integrating carbon quantum dots(CQDs)as a photogenerated carrier transfer bridge between ZnIn_(2)S_(4)and CeO_(2).The unique structure of ZnIn_(2)S_(4)/CQDs/CeO_(2)facilitates the efficient separation and transfer of photogenerated electron-hole pairs,while the CQDs act as a solid-state electron mediator,enhancing interfacial charge transfer and suppressing recombination.Under visible-light irradiation(λ≥420 nm),when the concentration of ZnIn_(2)S_(4)is 40%,the hydrogen generation rate of ZnIn_(2)S_(4)/CQDs/CeO_(2)-2 reaches 7.7 mmol·g^(-1)·h^(-1),which is 12.8 times higher than that of unmodified ZnIn_(2)S_(4)(0.6 mmol·g^(-1)·h^(-1))and significantly greater than that of ZnIn_(2)S_(4)/CeO_(2)(4.2 mmol·g^(-1)·h^(-1)).Furthermore,the all-solid Z-scheme configuration ensures excellent stability,as demonstrated by prolonged cycling tests.We investigated CQDs as a bridge to facilitate the vector transfer of photogenerated electrons from ZnIn_(2)S_(4)to CeO_(2)through density functional theory calculations.Additionally,X-ray photoelectron spectroscopy results confirmed the Z-scheme mechanism of photogenerated carrier transfer within the ZnIn_(2)S_(4)/CQDs/CeO_(2)heterojunction.This study not only demonstrates an effective approach for promoting charge transfer in nanocomposites using CQDs but also provides a new strategy for developing efficient hydrogen evolution photocatalysts without the involvement of precious metals.展开更多
Designing simple, efficient, and environmentally friendly methods to construct high-efficient photocatalysts is an important strategy to promote the further development of the field of photocatalysis. Herein, flower-l...Designing simple, efficient, and environmentally friendly methods to construct high-efficient photocatalysts is an important strategy to promote the further development of the field of photocatalysis. Herein, flower-like carbon quantum dots(CQDs)/Bi OBr composite photocatalysts have been prepared via in-situ synthesis by mechanical ball milling in the existence of ionic liquid. The CQDs/Bi OBr composites exhibit higher photo-degradation performance for tetracycline(TC) than Bi OBr monomer and the commercial Bi_(2)O_(3) under visible light irradiation. For comparison, the different Br sources and synthetic methods are chosen to prepare Bi OBr and CQDs/Bi OBr composites. Photocatalysts prepared by ball milling and ionic liquid present significantly enhanced photocatalytic performance for removing TC. In addition, the introduction of CQDs could distinctly enhance the photocatalytic performances of pure Bi OBr. The reason is that CQDs as electron acceptor effectively separate electrons and holes and inhibit their recombination. The intermediates during photocatalytic degradation were tested using liquid chromatography-mass spectrometry(LC-MS) and possible degradation pathways were given. During degradation, ·OH, O_(2)^(·-)and h^(+) were identified to be the main active species based on electron spin resonance(ESR) spectra and free radical trapping experiments. A possible mechanism of CQDs/Bi OBr with enhanced photocatalytic performances was further proposed.展开更多
基金supported by the National Natural Science Foundation of China(No.42403080)the Youth Innovation Promotion Asso-ciation of the Chinese Academy of Sciences(No.2022415)+1 种基金the Key Research and Development Program of Shaanxi Province(No.S2023-YF-LLRH-QCYK-0263)the Key Research and Development Programof Shaanxi Province(No.2023QCY-LL-16).
文摘The development of ZnO-based composites with high charge separation and effective inhibition of toxic by-products is admirable for effective photocatalysis of nitrogen oxides(NO_(x))oxidation.In this study,carbon quan-tum dots(CQDs)/ZnO hollow microspheres,synthesized through a rapid microwave-assisted method,achievedover a 30-fold higher NO_(x) removal efficiency compared to ZnO,with complete inhibition of NO_(2) by-products andgood durability.The enhanced photocatalytic activity was ascribed to the unique role of CQDs,as revealed byin-situ photoelectric techniques.Results demonstrated that the electron directional migration from ZnO to CQDsat the composite interface accounts for the enhanced charge separation.Active free radicals for NO_(x) oxidationwere identified,and in-situ diffuse reflectance infrared Fourier transform spectroscopy analysis elucidated theconversion pathways of NO_(x) oxidation under visible light irradiation.This work sheds light on the mechanismsof electron transfer and charge separation at the composite interface,offering guidance for designing superiorZnO-based photocatalysts for complete NO_(x) removal.
基金supported by the National Natural Science Foundation of China(Nos.22001026,22171233,22201193)Sichuan Science and Technology Program(No.2023NSFSC0109)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Hundred Talent Program of Sichuan University(No.YJ2021158)。
文摘The linker defect engineering for MOFs is a viable strategy that usually can effectively augment conductivity to further promote charge carrier separation,which is the most excellent conductivity of preserved metal clusters.However,the partially missing photosensitive linker often leads to the diminished light utilization efficiency.As we know,in the linker defect engineering,addressing the lack of photosensitivity while maintaining outstanding conductivity is still in its infancy.In this essay,the linkerdefective NH_(2)-MIL-125 was obtained by adding the glacial acetic acid regulator,subsequently,the excellent light-responsive Pt/CQDs with up-conversion effect was in-situ encapsulated into the enlarged pore space of linker-defective NH_(2)-MIL-125.It is excited that the fabricated dual-functional composite ideally integrates photosensitivity and conductivity for photocatalytic hydrogen evolution and NO elimination.The optimal Pt/CQDs@NM-125-4 exhibited very superior photocatalytic hydrogen evolution(28.75mmol/g),it was 11.63 times as that of the initial NH_(2)-MIL-125(2.47 mmol/g)and 1.4 times as that of the defective NM-125-4(20.46 mmol/g).In addition,the excellent photocatalytic NO removal efficiency was 52.12%for Pt/CQDs@NM-125-4,whereas the original NH_(2)-MIL-125 only reached 30%and the defective NM-125-4 achieved 44.96%.The corresponding optical and electrical characterization based on UV-vis,up-conversion photoluminescence(UCPL),and electrochemical impedance spectroscopy(EIS)etc.demonstrated the defect engineering accelerates the charge carriers transfer via enhancing conductivity,and the in-situ confined up-conversion Pt/CQDs promote the visible light response.Our work presents a feasible avenue to integrate photosensitivity and conductivity via in-situ fabricating excellent lightresponsive Pt/CQDs within linker-defective NH_(2)-MIL-125 for further significantly boosting photocatalytic performance.
基金supported by (Dr. Manika Khanuja, Nanomission, (DST)[DST/NM/NB/2018/203(G) (JMI)]UGC grant (No.F.4(201-FRP)/2015 (BSR))
文摘The endocrine-disrupting chemicals(EDCs)and antibiotics are causing negative effects on human beings and animals by disrupting the endocrine system and spreading antimicrobial resistance.The current need is to eradicate pharmaceutical waste from water bodies using advanced catalytic systems with high efficiency.Novel ternary carbon quantum dots(CQDs)decorated Z-Scheme WS_(2)-PANI nanocomposite was prepared by a green synthesis assisted in-situ polymerization for the photodegradation and detection of Estradiol(EST)and Nitrofurantoin(NFT).HRTEM micrographs revealed the formation of CQDs with a mean size of 4nm anchored on the surface of WS_(2)/PANI(width:PANI~20-30nm).The ternary nanocomposite showed excellent photocatalytic activity,degraded NFT(95.7%in 60min),and EST(96.6%in 60min).The rate kinetics study confirms the reaction followed pseudo first-order model.This heterostructure exhibited enhanced performances by modulating the energy level configuration,enhancing the absorption of visible light(2.4eV),and significantly improving the charge separation,three times higher than pristine WS_(2).These are highly favorable for increasing the generation of photoinduced charges and enhancing the overall performance of the catalyst.Further,the electrochemical sensor was prepared using CQDs@WS_(2)/PANI nanocomposite on a paper-based electrode.The CQDs@WS_(2)/PANI exhibit a linear response of 0.1-100nM,with a limit of detection of 13nM.This synergistic interfacial interaction resulted in the significantly improved electrochemical performance of the modified electrode.The proposed Z-scheme was justified by electron paramagnetic resonance(EPR)and scavenger experiment.An intermediate degradation pathway was also proposed.The synthesized materials were characterized using FESEM,HRTEM,XRD,FTIR,XPS,UV-visible spectroscopy,PL,and TRPL.Therefore,this study provides a direct approach to fabricate a heterojunction that combines two-dimensional,one dimensional,and zero-dimensional properties,enabling control over the energy level configuration and subsequent improvements in photocatalytic and electrocatalytic efficiency.
基金supported by the National Natural Science Foundation of China(NSFC)(No.52100101)and the National Scholarship Fund.
文摘NH_(2)-MIL-125 and its derivatives are receivingmore attention in various aspects of photocatalytic reactions,especially in the photocatalytic hydrogen peroxide(H_(2)O_(2))production from water(H_(2)O)and oxygen(O_(2)),which is a promising and sustainable strategy.However,the generation of H_(2)O_(2) from NH_(2)-MIL-125 is far from satisfactory due to rapid photo-generated carriers recombination and poor surface electron transfer.In the work,the composite photocatalyst CQDs/TiO_(2)/NH_(2)-MIL-125(C/T/NM)was designed for the first time by one-step hydrothermal method.TiO_(2) was in situ converted from partial NH_(2)-MIL-125(NM)during the successful loaded of Carbon quantum dots(CQDs)by hydrothermal process.The results indicated the typeⅡheterojunction was successfully constructed between the NM and TiO_(2) interface,which could promote the transmission of photo-generated electrons.In addition,the successful loaded of CQDs could effectively transfer and stored the photo-generated electrons to the photocatalyst surface to participate in the reaction,and further avoiding the recombination of photo-generated carriers.The C/T/NM composite photocatalyst achieved a H_(2)O_(2) generation of 455μmol/L for 5 hours under visible light without oxygen bubbling,whichwas 7.1 times superior to that of NM.The H_(2)O_(2) generation rate reached 645.4μM/(g·h),which was in priority in the reported literature under the same conditions.Finally,based on the active species capture experiments,energy band structure analysis and the photoelectrochemicalmeasurements,a possiblemechanism for the efficientH_(2)O_(2) generation through C/T/NM had been proposed.This work provided new ideas for designing NH_(2)-MIL-125 based composite photocatalysts for the production of H_(2)O_(2).
基金supported by the Natural Science Foundation of Shandong Province ZR2024MB087the National Natural Science Foundation of China(No.52122308,51973200,52202050,and 21905253)+3 种基金the Natural Science Foundation of Henan(202300410372)the Joint Fund of Science and Technology R&D Plan of Henan Province(232301420042)the China Postdoctoral Science Foundation(2022TQ0286)the Center for Modern Analysis and Gene Sequencing of Zhengzhou University for supporting this project。
文摘The development of highly active and stable bifunctional electrocatalysts in acidic media is crucial to hydrogen production by proton exchange membrane.In this study,we designed a RuO_(2)-IrO_(2)heterostructure catalyst coupled by carbon quantum dots(CQDs).The catalyst showed excellent electrocatalytic performance for water splitting under acidic conditions.The overpotentials of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)were as low as 180 and 15 mV at 10 mA/cm^(2)in 0.5 M H_(2)SO_(4),respectively.The acid electrolytic cell developed with RuO_(2)-IrO_(2)@CQDs as anode and cathode operated stably at 10 m A/cm^(2)for 120 h.In situ measurements and theoretical calculation reveal that the unique lattice oxygen mechanism path of RuO_(2)-IrO_(2)@CQDs can bypass the OOH^(*)intermediate and breaks the linear relationship of adsorbent evolution mechanism path,resulting in higher OER catalytic activity.
基金supported by the National Natural Science Foundation of China(No.22205058)Natural Science Foundation of Henan Province(No.252300421709)+1 种基金the Funding Plan of Key Scientific Research Projects in Colleges and Universities of Henan Province(No.23A150001)Foundation of Henan University of Technology(Nos.31401584,2023BS051,2021BS024,and 21421250).
文摘The development of efficient and stable visible-light-driven hydrogen(H_(2))generation photocatalysts plays a crucial role in sustainable energy conversion.In this study,we constructed an all-solid Z-scheme heterostructure by integrating carbon quantum dots(CQDs)as a photogenerated carrier transfer bridge between ZnIn_(2)S_(4)and CeO_(2).The unique structure of ZnIn_(2)S_(4)/CQDs/CeO_(2)facilitates the efficient separation and transfer of photogenerated electron-hole pairs,while the CQDs act as a solid-state electron mediator,enhancing interfacial charge transfer and suppressing recombination.Under visible-light irradiation(λ≥420 nm),when the concentration of ZnIn_(2)S_(4)is 40%,the hydrogen generation rate of ZnIn_(2)S_(4)/CQDs/CeO_(2)-2 reaches 7.7 mmol·g^(-1)·h^(-1),which is 12.8 times higher than that of unmodified ZnIn_(2)S_(4)(0.6 mmol·g^(-1)·h^(-1))and significantly greater than that of ZnIn_(2)S_(4)/CeO_(2)(4.2 mmol·g^(-1)·h^(-1)).Furthermore,the all-solid Z-scheme configuration ensures excellent stability,as demonstrated by prolonged cycling tests.We investigated CQDs as a bridge to facilitate the vector transfer of photogenerated electrons from ZnIn_(2)S_(4)to CeO_(2)through density functional theory calculations.Additionally,X-ray photoelectron spectroscopy results confirmed the Z-scheme mechanism of photogenerated carrier transfer within the ZnIn_(2)S_(4)/CQDs/CeO_(2)heterojunction.This study not only demonstrates an effective approach for promoting charge transfer in nanocomposites using CQDs but also provides a new strategy for developing efficient hydrogen evolution photocatalysts without the involvement of precious metals.
基金financially supported by the National Natural Science Foundation of China (Nos. 22108106, 22108108, 22109055, 21878134)Natural Science Foundation of Jiangsu Province (BK20210742)+2 种基金China Postdoctoral Science Foundation (No. 2020M680065)Hong Kong Scholar Program (No. XJ2021021)Key Laboratory of Electrochemical Energy Storage and Energy Conversion of Hainan Province (No. KFKT2021005)。
文摘Designing simple, efficient, and environmentally friendly methods to construct high-efficient photocatalysts is an important strategy to promote the further development of the field of photocatalysis. Herein, flower-like carbon quantum dots(CQDs)/Bi OBr composite photocatalysts have been prepared via in-situ synthesis by mechanical ball milling in the existence of ionic liquid. The CQDs/Bi OBr composites exhibit higher photo-degradation performance for tetracycline(TC) than Bi OBr monomer and the commercial Bi_(2)O_(3) under visible light irradiation. For comparison, the different Br sources and synthetic methods are chosen to prepare Bi OBr and CQDs/Bi OBr composites. Photocatalysts prepared by ball milling and ionic liquid present significantly enhanced photocatalytic performance for removing TC. In addition, the introduction of CQDs could distinctly enhance the photocatalytic performances of pure Bi OBr. The reason is that CQDs as electron acceptor effectively separate electrons and holes and inhibit their recombination. The intermediates during photocatalytic degradation were tested using liquid chromatography-mass spectrometry(LC-MS) and possible degradation pathways were given. During degradation, ·OH, O_(2)^(·-)and h^(+) were identified to be the main active species based on electron spin resonance(ESR) spectra and free radical trapping experiments. A possible mechanism of CQDs/Bi OBr with enhanced photocatalytic performances was further proposed.
