Computationally screening non-precious single atom catalysts for oxygen reduction in alkaline media

The performance of single-atom catalysts (SACs) containing Sc, Ti, V, Mn, Fe, Ni, Cu, and Pt on N-doped carbon (NC) as possible cathodes in advanced chlor-alkali electrolysis has been investigated by means of density functional theory (DFT) with the aim of finding candidates to improve the sluggish kinetics of the oxygen reduction reaction (ORR). A plausible mechanism is proposed for the ORR that allows making use of the computational hydrogen electrode (CHE) approach in this environment, and suitable models have been used to estimate the free-energy changes corresponding to the elementary reaction steps. The performance of the different catalysts has been analyzed in terms of the electrochemical-step symmetry index (ESSI) and Gmax descriptors. From these descriptors, the Cu-containing SAC is predicted to exhibit the highest catalytic activity which is consistent with a theoretical overpotential of 0.71 V vs. the standard hydrogen electrode (SHE) only, indicating that this type of catalysts in oxygen depolarized cathodes (ODCs) may overcome the limitations of the high cost and low abundance of Pt and other precious metals.