Unravelling the electrocatalytic activity of LaFeO3 towards oxygen reduction reaction

Abstract

The oxygen reduction reaction (ORR) is an important process in renewable energy technology such as in fuel cells. The main challenge with fuel cells is the sluggish reaction kinetics of O2 reduction, and to speed this up studies have been conducted to find an efficient and economical electrocatalyst. In the present work, we theoretically investigated the equilibrium structure and properties of the 3D bulk LaFeO3 perovskite using the GGA+U method implemented in Vienna Ab initio Simulation Package (VASP). Thereafter, we cleaved a (001) plane from the bulk LaFeO3 material and computationally modelled a 2D monolayer of LaFeO3. This 2D monolayer of LaFeO3 showed a band gap of 0 eV which depicts that it has the potential to be used as an electrocatalyst for fuel cell applications. Here, the complete ORR pathway has been explored on the surface of 2D monolayer LaFeO3 by employing the First-principles Density Functional Theory (DFT) methods implemented in the VASP code. Both, the associative and the dissociative reaction mechanisms have been explored by computing the change in Gibbs Free Energy (ΔG) for all the reaction steps of ORR. The present study reveals that 2D monolayer LaFeO3 exhibits exceptional electrocatalytic activity and favors the 4𝑒−associative mechanism over the dissociative one. This study proposes that 2D monolayer LaFeO3 can serve as an alternate ORR electrocatalyst to expensive platinum (Pt) in fuel cells.