The electrolysis of water and the electrocatalytic production of hydrogen peroxide, H2O2, is central to many electrochemical water treatment applications including nutrient recovery, disinfection, and advanced oxidation processes. Here, we use density functional theory (DFT) calculations to evaluate the ability of high-entropy alloys (HEAs) to electro-catalyze hydroxyl radicals and H2O2 production. HEAs are relatively new materials made of four or more principal metallic elements combined in comparable proportions and stabilized in single-phase by the configurational entropy of mixing. The high tunability provided by the large diversity of potential reactive sites in HEAs has made them very attractive materials for electrocatalysis applications. However, our understanding of reaction mechanisms underlying the catalytic properties of HEAs remains poor, and rational design rules to optimize their performance based on their chemical composition are lacking. Furthermore, the design space of HEAs is incredibly vast, which makes experimental screening unfeasible. Here, we use DFT simulations to calculate the adsorption energy of various oxygen reaction intermediates on the surface of HEAs as a function of the alloy stoichiometry, which combined with the theoretical framework develop by Norskov and co-workers, gives us insight into the ability of HEAs to catalyze reactions relevant to electrochemical water treatment applications. Specifically, we study important intermediates for water electrolysis and electrochemical generation of H2O2, namely oxygen (O2), superoxide anion (O2–), oxyl (O●), hydroxyl (OH●), and hydroperoxyl (OOH●) radicals. Our results provide insight into the electrocatalytic activity of HEAs and constitute a first step towards the rational design of electrodes with tunable performance.

DFT study of high-entropy alloys as electrocatalysts for water treatment applications

ACS Spring Meeting 2021

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