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

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.