Computational Design Principles of Two-Center First-Row Transition Metal Oxide Oxygen Evolution Catalysts

computational screens for oxygen evolution reaction (OER) catalysts based on Sabatier analysis have seen great success in recent years; however, the concept of using chemical descriptors to form a reaction coordinate has not been put under scrutiny for complex systems. In this paper, we examine critically the use of chemical descriptors as a method for conducting catalytic screens. Applying density functional theory calculations to a two-center metal oxide model system, we show that the Sabatier analysis is quite successful for predicting activities and capturing the chemical periodic trends expected for the first-row transition metal series, independent of the proposed mechanism. We then extend this analysis to heterodimer metallic systems-metal oxide catalysts with two different catalytically active metal centers-and find signs that the Sabatier analysis may not hold for these more complex systems. By performing a principal component analysis on the computed redox potentials, we show. (1) that a single chemical descriptor inadequately describes heterodimer overpotentials and (2) mixed metal overpotentials cannot be predicted using only pure-metal redox potentials. We believe that the analysis presented in this article shows a need to move beyond the simple chemical descriptor picture when studying more complex mixed metal oxide OER catalysts.