Substrate-dependence of the Ru active unit anchored on metal oxides for the oxygen evolution reaction

Abstract

Designing ruthenium (Ru)-based catalysts for the acidic oxygen evolution reaction (OER) remains highly challenging due to the intrinsic instability of the Ru active site. Anchoring the Ru site on other metal oxides is a widely used strategy. To elucidate how metal-oxide substrates influence the performance of anchored Ru sites under acidic OER, we established a screening framework to identify the potential metal oxides (e.g., rutile-, spinel-, pyrochlore- and perovskite-type) by density functional theory calculations and discussed the substrate-dependence of the anchored Ru active site. Applying a set of predetermined criteria, we screened 39 promising candidates, including 11 rutile-, 14 spinel- and 14 pyrochlore-type metal oxides, from 1513 metal oxides in the Materials Project Database, which could be suitable for stabilizing the Ru active center. Perovskite-type metal oxides are unsuitable due to their unstable structural framework with weaker metal–oxygen bonds. The rutile-, spinel- and pyrochlore-type metal oxide substrates can break the linear scaling relationships between the key OER intermediates on the Ru site; especially, spinel- and pyrochlore-type oxides exhibit a smaller slope in this relationship, indicating a stronger substrate effect and their greater potential as platforms for designing Ru-based catalysts. This work provides guidance for the experimental discovery of suitable metal oxide substrates for constructing Ru-based catalysts for the OER and offers fundamental insights into the substrate-dependent behavior of the Ru site on different metal oxides.