Unraveling the O₂ Reduction Reaction on 2D Monolayer LaNiO₃ Perovskite

The O₂ reduction reaction (ORR) occurring at cathodes is a critical reaction in many electrochemical energy-converting devices such as fuel cells. The reaction kinematics of the ORR is generally very slow with high overpotentials and needs to be enhanced by using an efficient electrocatalyst. The highly recognized Pt-based electrocatalyst needs to be replaced with a low-cost non-noble metal-based electrocatalyst for catalyzing the ORR. We theoretically studied the structural and electronic properties of 3D bulk LaNiO₃ perovskite. We have cleaved the (0 0 1) surface from 3D LaNiO₃, which has a zero band gap (E _g), to create 2D monolayer LaNiO₃ computationally and studied its electronic properties. Our study demonstrates that the 2D monolayer LaNiO₃ is a suitable candidate for catalyzing the ORR because of its high catalytic activity with a tiny electronic band gap of 0.25 eV. We explored the ORR mechanism on the 2D monolayer LaNiO₃ perovskite by inspecting each intermediate. Our present findings show that the 2D monolayer LaNiO₃ can efficiently catalyze the ORR through a four-electron (4e^-) reduction reaction due to the excellent catalytic activity of its basal plane, which accords with the experimental findings. The change in Gibbs free energy (ΔG) calculations of various intermediate steps of the ORR demonstrates that all reaction steps are spontaneous and thermodynamically favorable. The 2D monolayer LaNiO₃ perovskite can be a potential candidate for catalyzing the ORR efficiently. This study helps to enable the development of high-activity, stable 2D perovskites for use in future solid oxide fuel cells and related applications in green energy technologies.