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Effect of Bi-doping on the electrocatalytic properties of LaFeO3 powders prepared by sol–gel method

Li, Wanjun, Yang, Fujun, Xiong, Peng, Jia, Yunjie, Liu, Jiawei, Yan, Xinsui, Chen, Xiaoqin
Journal of materials science 2019 v.54 no.10 pp. 7460-7468
Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, catalysts, iron, oxygen, powders, sol-gel processing
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.