Pure nanocrystalline LaAlO3 powders were synthesized by W/O microemulsion consisting of water, Tween-80 (surfactant), n-Hexyl alcohol (cosurfactant), and cyclohexane (oil). Precursor hydroxides were precipitated in th...Pure nanocrystalline LaAlO3 powders were synthesized by W/O microemulsion consisting of water, Tween-80 (surfactant), n-Hexyl alcohol (cosurfactant), and cyclohexane (oil). Precursor hydroxides were precipitated in the aqueous cores of W/O microemulsions and then separated and calcined to obtain nanocrystalline LaAlO3 powder. The decomposition behavior of the precursors hydroxides were studied by thermogravimetry analysis (TGA). The precursor hydroxides were calcined at different temperatures and the phase evolution was studied by X-ray powder diffraction (XRD). And the morphology of LaAlO3 powder was studied by transmission electron microscopy (TEM). The crystallite size was less than 50 nm and the shape of the particle is approximately spherical.展开更多
In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,...In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,including XRD,N_(2) adsorptiondesorption,TEM,XPS,H2TPR and TG.The results show that the existence of LaAlO_(3) perovskite can enhance the dispersion and sintering resistance of metal nanoparticles and facilitate the transfer of carbon deposits from active sites to the support.Interestingly,the perovskite nanoparticles can also inhibit the reduction of CuOx and the formation of PtCu alloys,resulting in the suitable interaction between Pt and Cu.The PtCu/LaAlO_(3)/SiO_(2)catalyst exhibits the optimal dehydrogenation performance with an isobutane conversion of 47%and isobutene selectivity of 92%after 310 min reaction,which was ascribed to the unique role of LaAlO_(3) perovskite as well as the appropriate PtCu interaction.展开更多
LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room temperature.The abnormally strong PPC has attracted immense research interest due to its possible applications ...LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room temperature.The abnormally strong PPC has attracted immense research interest due to its possible applications in optically-tunable electronic devices.Despite its promise,the fundamental understanding of the PPC in the LAO/STO heterostructures is still elusive.Herein,we report that the giant PPC origi-nates from the photo-induced valence change in oxygen vacancies near the LAO/STO interface.Our spec-tral analysis of the photocurrent and the model-fitting study consistently show that the ionized oxygen vacancies near the interface are neutralized during the electron relaxation process.They hinder the complete relaxation of the photoexcited electrons by the deeply-located oxygen vacancies and result in the strong PPC.The change in the ionization state distribution of the oxygen vacancies is probed by the per-sistent noise behavior at the frequency between 1 kHz and 20 kHz regime.These results provide insight into the role of oxygen vacancies in influencing the internal charge distribution and triggering the PPC phenomena in complex oxide heterostructures.展开更多
基金Natural Science Foundation Project of Chongqing Science and Technology Commission (2005BA4019)
文摘Pure nanocrystalline LaAlO3 powders were synthesized by W/O microemulsion consisting of water, Tween-80 (surfactant), n-Hexyl alcohol (cosurfactant), and cyclohexane (oil). Precursor hydroxides were precipitated in the aqueous cores of W/O microemulsions and then separated and calcined to obtain nanocrystalline LaAlO3 powder. The decomposition behavior of the precursors hydroxides were studied by thermogravimetry analysis (TGA). The precursor hydroxides were calcined at different temperatures and the phase evolution was studied by X-ray powder diffraction (XRD). And the morphology of LaAlO3 powder was studied by transmission electron microscopy (TEM). The crystallite size was less than 50 nm and the shape of the particle is approximately spherical.
基金the National Natural Science Foundation of China(21776214)and State Key Laboratory of Chemical Resource Engineering.
文摘In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,including XRD,N_(2) adsorptiondesorption,TEM,XPS,H2TPR and TG.The results show that the existence of LaAlO_(3) perovskite can enhance the dispersion and sintering resistance of metal nanoparticles and facilitate the transfer of carbon deposits from active sites to the support.Interestingly,the perovskite nanoparticles can also inhibit the reduction of CuOx and the formation of PtCu alloys,resulting in the suitable interaction between Pt and Cu.The PtCu/LaAlO_(3)/SiO_(2)catalyst exhibits the optimal dehydrogenation performance with an isobutane conversion of 47%and isobutene selectivity of 92%after 310 min reaction,which was ascribed to the unique role of LaAlO_(3) perovskite as well as the appropriate PtCu interaction.
基金This work is supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Nos.2021R1C1C1011219 and2021R1A4A1032085)K.Eomwould like to acknowledge the support by National Research Founda-tion of Korea through the Basic Science Research Program(NRF-2022R1C1C2010693)J.W.Lee acknowledges the support from Ba-sic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2022R1I1A1A01068965).
文摘LaAlO_(3)/SrTiO_(3)(LAO/STO)heterostructures have shown a strong persistent photoconductivity(PPC)at room temperature.The abnormally strong PPC has attracted immense research interest due to its possible applications in optically-tunable electronic devices.Despite its promise,the fundamental understanding of the PPC in the LAO/STO heterostructures is still elusive.Herein,we report that the giant PPC origi-nates from the photo-induced valence change in oxygen vacancies near the LAO/STO interface.Our spec-tral analysis of the photocurrent and the model-fitting study consistently show that the ionized oxygen vacancies near the interface are neutralized during the electron relaxation process.They hinder the complete relaxation of the photoexcited electrons by the deeply-located oxygen vacancies and result in the strong PPC.The change in the ionization state distribution of the oxygen vacancies is probed by the per-sistent noise behavior at the frequency between 1 kHz and 20 kHz regime.These results provide insight into the role of oxygen vacancies in influencing the internal charge distribution and triggering the PPC phenomena in complex oxide heterostructures.
