Narrow bandgap semiconductor MgIn_(2)S_(4) has been readily grown onto In_(2)O_(3) nanofibers by an in situ growing method.The so-formed MgIn_(2)S_(4)-In_(2)O_(3) hybrid nanofibers are characterized by strong visible ...Narrow bandgap semiconductor MgIn_(2)S_(4) has been readily grown onto In_(2)O_(3) nanofibers by an in situ growing method.The so-formed MgIn_(2)S_(4)-In_(2)O_(3) hybrid nanofibers are characterized by strong visible light absorption and intimate MgIn_(2)S_(4)/In_(2)O_(3) heterointerfaces.Under visible light illumination(λ≥400 nm),the hybrid nanofibers demonstrate an exceptionally high photocatalytic activity for Escherichia coli(E.coli)disinfection,outcompeting pristine MgIn_(2)S_(4),naked In_(2)O_(3) nanofibers,and many other photocatalytic systems reported.Specifically,the hybrid nanofibers achieve a 7 log reduction in viable cells for merely 20 min illumination while pristine MgIn_(2)S_(4) and naked In_(2)O_(3) nanofibers alone are almost inactive.Further analysis indicates that the hybrid nanofibers essentially form a type-II semiconductor heterojunctions which enable spatial separation of photocarriers.Owing to the intimate heterointerfaces,photocarriers can be promptly separated and accumulated respectively in In_(2)O_(3) and MgIn_(2)S_(4) thereby allowing continuous generation of copious reactive species for disinfection.This work signifies the usefulness of heterointerfaces in promoting photocarrier separation and provides a useful strategy to upgrade photocatalytic performance from otherwise almost inactive semiconductors.展开更多
Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)particles.This research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis kinetics.The effects of the flow field g...Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)particles.This research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis kinetics.The effects of the flow field generated by different agitators and baffles in the crystallizer,the initial free acid concentration,the initial equivalent TiO_(2)concentration,and the temperature on the hydrolysis progress and powder morphology were systematically studied.The results show that the flow field in a crystallizer can significantly affect the morphology and particle size of the powders,and the axial flow can improve the sphericity of the powders.The increased free HCl and equivalent TiO_(2)concentrations in the pregnant solution inhibit the forward hydrolysis reaction,prolong the time to reach equilibrium,and reduce the yield.An appropriate temperature matching the compositions of the pregnant solution is crucial for the powder morphology and size.Powders with sizes ranging from around 5 um-40μm can be tuned under controlled flow field,solution compositions,and temperature conditions.In addition,the Cheng and Wunderlich modified Avrami equation was used for the crystallization kinetic modeling.The effects of the free HCl concentration,equivalent TiO_(2)concentration,and hydrolysis temperature are reflected in the reaction rate constant and active nuclei reduction index.Increasing the free HCl and equivalent TiO_(2)concentrations will reduce the reaction rate constant and accelerate the deactivation of the active nuclei,thus increasing the final powder size,while increasing the temperature will lead to the opposite results.展开更多
基金National Natural Science Foundation of China(Grant Nos.51972233,52172225)the Science and Technology Commission of Shanghai Municipality(Grant No.19DZ2271500)the Fundamental Research Funds for the Central Universities for funding.
文摘Narrow bandgap semiconductor MgIn_(2)S_(4) has been readily grown onto In_(2)O_(3) nanofibers by an in situ growing method.The so-formed MgIn_(2)S_(4)-In_(2)O_(3) hybrid nanofibers are characterized by strong visible light absorption and intimate MgIn_(2)S_(4)/In_(2)O_(3) heterointerfaces.Under visible light illumination(λ≥400 nm),the hybrid nanofibers demonstrate an exceptionally high photocatalytic activity for Escherichia coli(E.coli)disinfection,outcompeting pristine MgIn_(2)S_(4),naked In_(2)O_(3) nanofibers,and many other photocatalytic systems reported.Specifically,the hybrid nanofibers achieve a 7 log reduction in viable cells for merely 20 min illumination while pristine MgIn_(2)S_(4) and naked In_(2)O_(3) nanofibers alone are almost inactive.Further analysis indicates that the hybrid nanofibers essentially form a type-II semiconductor heterojunctions which enable spatial separation of photocarriers.Owing to the intimate heterointerfaces,photocarriers can be promptly separated and accumulated respectively in In_(2)O_(3) and MgIn_(2)S_(4) thereby allowing continuous generation of copious reactive species for disinfection.This work signifies the usefulness of heterointerfaces in promoting photocarrier separation and provides a useful strategy to upgrade photocatalytic performance from otherwise almost inactive semiconductors.
基金supported by the Key Research Program of the Chinese Academy of Sciences(grant number ZDRWCN-2021-3)the Youth Innovation Promotion Association CAS(grant number 2018065)+1 种基金the National Natural Science Foundation of China(grant number 51771179)the Beijing Natural Science Foundation(grant number 2192056).
文摘Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)particles.This research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis kinetics.The effects of the flow field generated by different agitators and baffles in the crystallizer,the initial free acid concentration,the initial equivalent TiO_(2)concentration,and the temperature on the hydrolysis progress and powder morphology were systematically studied.The results show that the flow field in a crystallizer can significantly affect the morphology and particle size of the powders,and the axial flow can improve the sphericity of the powders.The increased free HCl and equivalent TiO_(2)concentrations in the pregnant solution inhibit the forward hydrolysis reaction,prolong the time to reach equilibrium,and reduce the yield.An appropriate temperature matching the compositions of the pregnant solution is crucial for the powder morphology and size.Powders with sizes ranging from around 5 um-40μm can be tuned under controlled flow field,solution compositions,and temperature conditions.In addition,the Cheng and Wunderlich modified Avrami equation was used for the crystallization kinetic modeling.The effects of the free HCl concentration,equivalent TiO_(2)concentration,and hydrolysis temperature are reflected in the reaction rate constant and active nuclei reduction index.Increasing the free HCl and equivalent TiO_(2)concentrations will reduce the reaction rate constant and accelerate the deactivation of the active nuclei,thus increasing the final powder size,while increasing the temperature will lead to the opposite results.
