Substrate-Dependence of Ru Active Unit Anchored on Metal Oxides for Oxygen Evolution Reaction

Abstract

Designing ruthenium(Ru)-based catalysts for acidic oxygen evolution reaction (OER) remains highly challenging due to the intrinsic instability of Ru active site. Anchoring Ru site on other metal oxides is a widelyused strategy. To elucidate how metal-oxide substrates influence the performance of anchored Ru sites under acidic OER, we established a screening framework to identify potential metal oxides (e.g., rutile-, spinel-,pyrochlore and perovskite-type ones) by density functional theory calculations, and discussed the substrate-dependence of Ru active site anchored on them. 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 Materials Project Database, which could be suitable for stabilizing Ru active center.Perovskite-type metal oxides are unsuitable due to their unstable structure framework with weaker metal-oxygen bonds.Rutile-, spinel-and pyrochlore-type metal oxide substrates can break the linear scaling relationships between key OER intermediates on Ru site; especially, spinel-and pyrochlore-type ones exhibit 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 experimental discovery of suitable metal oxide substrates for constructing Ru-based catalysts for OER, and offers fundamental insights into the substrate-dependent behavior of Ru site on different metal oxides.