Erbium-substituted LaFeO3 perovskite nanoparticles for pseudocapacitive energy storage applications

Abstract

LaFeO3 perovskites are promising candidates for supercapacitor electrodes, yet their performance is limited by low ionic conductivity and restricted active surface area. In this work, Er3+ was introduced at the A-site of LaFeO3 to increase defect concentration and improve ion transport within the perovskite lattice. Nanoparticles with compositions of La1−xErxFeO3 (x = 0, 0.1, 0.2, and 0.3) were synthesized using a sol–gel auto-combustion method and characterized by XRD, SEM, TEM, and XPS to establish structural refinement, morphological evolution, and defect chemistry. Among all compositions, La0.8Er0.2FeO3 delivered the highest specific capacitance of 288.2 F g−1 at 5 mV s−1 and 201.4 F g−1 at 2 A g−1. XPS revealed a significant increase in defect concentration, accompanied by the formation of Fe2+via electron transfer from O2− ions, consistent with enhanced defect-assisted charge transport. Shortened oxygen diffusion pathways arising from reduced bond lengths further contributed to improved ionic mobility. The Ragone analysis indicated that the Er-doped composition exhibits superior energy and power densities compared to pristine LaFeO3. These results establish Er substitution as an effective strategy for defect engineering in LaFeO3, enabling improved charge-storage behavior and positioning Er-doped LaFeO3 as a strong candidate for next-generation pseudocapacitive energy-storage applications.