Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFeOhave been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD, TEM, SEM and HRTEM. UV-vis di...Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFeOhave been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD, TEM, SEM and HRTEM. UV-vis diffuse reflectance spectra and Mott–Schottky plots show that the band structure of the CaFeOnanorods is narrower than that of the CaFeOnanoparticles synthesized by conventional method. The enhancement of the visible-light absorption is due to narrowness of the band gap in CaFeOnanorods. The appropriate ratio between the molten salt and the CaFeOprecursors plays an important role in inhibiting the growth of the crystals along the(201) plane to give the desired nanorod morphology. This work not only demonstrates that highly pure p-type CaFeOsemiconductor with tunable band structure and morphology could be obtained using the molten salt strategy, but also affirms that the bandgap of a semiconductor may be tunable by monitoring the growth of a particular crystal plane.Furthermore, the facile eutectic molten salt method developed in this work may be further extended to fabricate some other semiconductor nanomaterials with a diversity of morphologies.展开更多
A simple sol-gel approach is proposed herein to fabricate CaFe_(2)O_(4)for the degradation of various organic pollutants(rhodamine B(RhB),tetracycline hydrochloride,humic acid,and methylene orange)under LED light irra...A simple sol-gel approach is proposed herein to fabricate CaFe_(2)O_(4)for the degradation of various organic pollutants(rhodamine B(RhB),tetracycline hydrochloride,humic acid,and methylene orange)under LED light irradiation mediated by peroxymonosulfate(PMS).The results indicate that the calcination temperature can significantly influence the performance of CaFe_(2)O_(4)for PMS activation,and the CaFe_(2)O_(4)sample obtained at 800℃(CaFe_(2)O_(4)-800)exhibits the best efficiency in degrading RhB,which is much higher than that of Fe_2o_(3)-800.This can be attributed to the efficient separation of photogenerated electrons(e^(-))and holes(h^(+))by PMS,which is validated by transient photocurrent response and photoluminescence measurements.Results from density functio nal theo ry calculations indicate that the valence band of CaFe_(2)O_(4)-800 exhibits a high concentration of carriers and weak localization of electrons,which are favorable for PMS activation.Radical scavenging results confirm that h^(+)and O_(2)^(·-)are the dominant reactive species.Moreover,CaFe_(2)O_(4)-800 not only demonstrated a stable performance during eight cycling runs with negligible iron leaching but also exhibited excellent degradation efficiency under natural water and sunlight.Finally,the mechanism and pathway of RhB degradation by the CaFe_(2)O_(4)-800/PMS/LED system are also proposed.This work presents the enormous prospect of CaFe_(2)O_(4)as an environmentally benign photocatalyst for PMS activation.展开更多
基金supports from the National Natural Science Foundation of China(nos.21473189 and21503100)the 973 National Basic Research Program of China(no.2014CB239401)the Natural Science Foundation of Jiangxi Province of China(no.20151BAB213010)
文摘Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFeOhave been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD, TEM, SEM and HRTEM. UV-vis diffuse reflectance spectra and Mott–Schottky plots show that the band structure of the CaFeOnanorods is narrower than that of the CaFeOnanoparticles synthesized by conventional method. The enhancement of the visible-light absorption is due to narrowness of the band gap in CaFeOnanorods. The appropriate ratio between the molten salt and the CaFeOprecursors plays an important role in inhibiting the growth of the crystals along the(201) plane to give the desired nanorod morphology. This work not only demonstrates that highly pure p-type CaFeOsemiconductor with tunable band structure and morphology could be obtained using the molten salt strategy, but also affirms that the bandgap of a semiconductor may be tunable by monitoring the growth of a particular crystal plane.Furthermore, the facile eutectic molten salt method developed in this work may be further extended to fabricate some other semiconductor nanomaterials with a diversity of morphologies.
基金financially supported by the National Natural Science Foundation of China(No.51604194)the Natural Science Foundation of Hubei Province of China(No.2016CFB169)+2 种基金the China Scholarship Council(No.201808420137)the Outstanding Talent Research Fund of Zhengzhou University(No.32340034)the Nanyang Environment and Water Research Institute(Core Fund),Nanyang Technological University,Singapore。
文摘A simple sol-gel approach is proposed herein to fabricate CaFe_(2)O_(4)for the degradation of various organic pollutants(rhodamine B(RhB),tetracycline hydrochloride,humic acid,and methylene orange)under LED light irradiation mediated by peroxymonosulfate(PMS).The results indicate that the calcination temperature can significantly influence the performance of CaFe_(2)O_(4)for PMS activation,and the CaFe_(2)O_(4)sample obtained at 800℃(CaFe_(2)O_(4)-800)exhibits the best efficiency in degrading RhB,which is much higher than that of Fe_2o_(3)-800.This can be attributed to the efficient separation of photogenerated electrons(e^(-))and holes(h^(+))by PMS,which is validated by transient photocurrent response and photoluminescence measurements.Results from density functio nal theo ry calculations indicate that the valence band of CaFe_(2)O_(4)-800 exhibits a high concentration of carriers and weak localization of electrons,which are favorable for PMS activation.Radical scavenging results confirm that h^(+)and O_(2)^(·-)are the dominant reactive species.Moreover,CaFe_(2)O_(4)-800 not only demonstrated a stable performance during eight cycling runs with negligible iron leaching but also exhibited excellent degradation efficiency under natural water and sunlight.Finally,the mechanism and pathway of RhB degradation by the CaFe_(2)O_(4)-800/PMS/LED system are also proposed.This work presents the enormous prospect of CaFe_(2)O_(4)as an environmentally benign photocatalyst for PMS activation.
