A first-principles study of doping effect on enhancing ORR performance of Sr–Ni–Nb co-doped LaFeO3 perovskite

Abstract

The development of oxygen reductive reaction (ORR) electrocatalyst with high-stability, conductivity and activity is of great importance for improving the conversion efficiency of Solid Oxide Fuel Cell (SOFC). Although the ORR performance of LaFeO3 perovskite (LFO) is not excellent, it is a promising cathode for SOFC duo to its low-cost peculiarity and adequate compatibility with electrolyte. In this work, the Ni–Nb and Sr were partially doped to Fe and La sites of LFO, respectively, to evaluate the doping effect on ORR ability. The increased formation energy illustrated that Nb-doping significantly enhanced the stability of LFO, while Ni-3d band emerged as the minimum conductive band mainly contributed to reduce the band gap. Moreover, the overpotential of LFO with Sr-doping (LSFO) was sharply reduced from 0.60 V to 0.34 V, which was possibly attributed to the decrease of eg-filling (less than 2), and hence increased the binding energy. Although surface O-vacancy (Ov) is more favorable to be induced than sublayer, the sublayer Ov facilitates to reduce the ORR overpotential. The electron variation exploration of Sr–Ni–Nb co-doped LFO provides important guidance for the design of high-efficient ORR catalyst for SOFC with high stability, and superior conductivity, as well as low overpotential.