Platinum Group and Transition Metal Alloy Electrocatalysts for Oxygen Evolution Reaction

Oxygen evolution reaction (OER) is important for green energy production and storage, and iridium oxide is the current benchmark for OER catalysts, but scarcity, high cost, and a negative environmental impact related to mining of precious metals limits their utility. Some progress has been made in identifying new metal and metal-oxide catalysts for this purpose, but industrial replacements remain out of reach. Studies of binary and some ternary alloys have shown increased catalyst performance with tuned selectivity and durability, yet the number of studies of alloys of 4 or more metals has been extremely limited. We have investigated quaternary alloys of noble and transition metals for OER by combinatorial methods. Samples were synthesized via magnetron sputtering, and a home-built scanning electrochemical system was used to screen samples based on cyclic voltammetry and electrochemical impedance spectroscopy. Data were analyzed based on a differential Tafel plot to determine the kinetics of the primary reaction. These results were then fed into various multi-target machine learning algorithms, one of which was selected for use based upon its ability to provide physically meaningful predictions in order to help identify various relationships to understand the mechanisms by which the reaction takes place. Here, we present the results of this comprehensive study.