Understanding the catalytic performances of metal-doped Ta2O5 catalysts for acidic oxygen evolution reaction with computations

Abstract

The design of stable and active alternative catalysts to iridium oxide for the anodic oxygen evolution reaction (OER) has been a long pursuit in acidic water splitting. Tantalum pentoxide (Ta₂O₅) has the merit of great acidic stability but poor OER performance, yet strategies to improve its intrinsic OER activity are highly desirable. Herein, by using density functional theory (DFT) calculations combined with aqueous stability assessment from surface Pourbaix diagrams, we systematically evaluated the OER activity and acidic stability of 14 different metal-doped Ta₂O₅ catalysts. Apart from the experimentally reported Ir-doped Ta₂O₅, we computationally identified Ru- and Nb-doped Ta₂O₅ catalysts as another two candidates with reasonably high stability and activity in acidic OER. Our study also underscores the essence of considering stable surface states of catalysts under working conditions before a reasonable activity trend can be computationally achieved.