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
ZnO-based catalysts have been widely used in hydrogenation reactions,but less attention has been paid to the electrocatalytic hydrogenation process on ZnO electrodes.In this work,the preparation of hydrogen species an...ZnO-based catalysts have been widely used in hydrogenation reactions,but less attention has been paid to the electrocatalytic hydrogenation process on ZnO electrodes.In this work,the preparation of hydrogen species and the associ-ated reduction properties under electrochemi-cal processes in aqueous solutions have been in-vestigated on ZnO and Au/ZnO electrodes.The measurements of cyclic voltammetry(CV),X-ray diffraction,and electron paramagnetic resonance(EPR)confirm the formation of hydro-gen species on the interstitial sites(Hi)or on the oxygen vacancy sites(H_(O)).The hydrogena-tion reaction of p-nitrophenol(pNP)at 40μmol/L occurs on both ZnO and Au/ZnO elec-trodes,and the hydrogenation reduction performance of Au/ZnO electrode is better than that of ZnO electrode.CVs show H_(O)species is much more reactive with pNP than Hi species.Compared with the ZnO electrode,the presence of Au on ZnO promotes the formation of H_(O)species and improves the electro-reduction performance to pNP.These results help us to un-derstand the reaction processes related to the electrochemical hydrogenation on ZnO and Au/ZnO surfaces and shed new light on the design of new catalytic hydrogenation systems.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 Key Re-search and Development Program of China(No.2021YFA1500403)the National Natural Science Foundation of China(No.21773047 and No.U1832180)partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘ZnO-based catalysts have been widely used in hydrogenation reactions,but less attention has been paid to the electrocatalytic hydrogenation process on ZnO electrodes.In this work,the preparation of hydrogen species and the associ-ated reduction properties under electrochemi-cal processes in aqueous solutions have been in-vestigated on ZnO and Au/ZnO electrodes.The measurements of cyclic voltammetry(CV),X-ray diffraction,and electron paramagnetic resonance(EPR)confirm the formation of hydro-gen species on the interstitial sites(Hi)or on the oxygen vacancy sites(H_(O)).The hydrogena-tion reaction of p-nitrophenol(pNP)at 40μmol/L occurs on both ZnO and Au/ZnO elec-trodes,and the hydrogenation reduction performance of Au/ZnO electrode is better than that of ZnO electrode.CVs show H_(O)species is much more reactive with pNP than Hi species.Compared with the ZnO electrode,the presence of Au on ZnO promotes the formation of H_(O)species and improves the electro-reduction performance to pNP.These results help us to un-derstand the reaction processes related to the electrochemical hydrogenation on ZnO and Au/ZnO surfaces and shed new light on the design of new catalytic hydrogenation systems.
