为了研究A位掺杂对LaFeO3的结构及电化学性能的影响,本文中采用溶胶凝胶法制备并在空气中800℃退火获得La1-x,BixFeO3纳米颗粒.研究发现,随着Bi元素的掺杂,材料的氧还原(ORR)性能显著提升.通过一系列电化学测式发现,无论是起始电位、极限电流密度,还是Tafel斜率与未掺杂样品相比都有显著提升,并在x=0.15时得到最优的ORR性能.这可能是因为Bi的掺杂使得LaFeO3发生晶格畸变并导致材料中的氧空位增加,从而得到更优的ORR性能.

The catalysts are often used in fuel cells and metal-air batteries to speed up electrochemical reactions. In this study, we prepared CoFe2O4 nanoparticles with mainly inverse spinel structure and FeCo2O4 nanoparticles with mainly spinel structure as bifunctional catalysts by hydrothermal method. After annealing at 350 degrees C, pure CoFe2O4 and FeCo2O4 nanoparticles with uniform size distribution have been obtained. The CoFe2O4 nanoparticles showed high current density of 5.5 mA/cm(2) at -0.8 V in the ORR test. It's low Tafel slope of 83.0 mV/dec further confirmed the excellent ORR catalytic properties of CoFe2O4 nanoparticles. Furthermore, the CoFe2O4 nanoparticles also showed good OER properties with satisfied current density of 35.7 mV/cm(2) at l.0 V and low OER Tafel slope of 71.0 mV/dec. Both the ORR and OER properties of CoFe2O4 nanoparticles showed good time stability which were compared with FeCo2O4 nanoparticles. These results indicated that CoFe2O4 nanoparticles with mainly inverse spinel structure had better electrocatalytic performance than FeCo2O4 nanoparticles with mainly spinel structure. The CoFe2O4 nanoparticles with mainly inverse spinel structure show a significant potential application in rechargeable battery. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

采用改进固相法制备c轴择优取向Bi6 Ti3 Fe1. 7 Ni0. 3 O18陶瓷材料,重点研究Bi6 Ti3 Fe1. 7 Ni0. 3 O18材料磁性能的各向异性及光吸收特性.X线衍射结果表明,由改进固相法制备的陶瓷样品均具有c轴择优取向,随着烧结温度的升高,样品的c轴择优取向度增加.磁性测试结果表明,所有样品面内的饱和磁化强度( Ms)均大于面外的饱和磁化强度.对光吸收性能的分析表明,Bi6 Ti3 Fe1. 7 Ni0. 3 O18具有两条吸收边,对应的直接带隙分别为2. 01 eV和2. 44 eV.

In this work, La1−xBixFeO3 powders (0 ≤ x ≤ 0.2) were prepared by sol–gel route. The orthorhombic Pbnm structure of the pure LaFeO3 powder was confirmed by X-ray diffraction. However, there was a changing tendency from the orthorhombic Pbnm structure into the rhombohedral R3c structure with the increase in Bi-doping. The structural and symmetric change of Bi-doped LaFeO3 samples was further verified by the Raman spectra which changed from fundamental 5 modes into 7 modes. The X-ray photoelectron spectra (XPS) revealed that more oxygen vacancies, Fe3+ and Fe4+, existed in Bi-doped LaFeO3 sample. Detailed CV, LSV and EIS analyses had provided conclusive evidence that the oxygen vacancy Fe3+ and Fe4+ played an important contribution to the electrocatalytic activity. The best ORR catalytic effect was observed in La0.85Bi0.15FeO3 catalyst. These results suggest that the Bi-doping is a significative effort to enhance the activities of perovskite electrocatalysts.