The role of metastability in enhancing water-oxidation activity

TL;DR

This study uses density functional theory to explore how metastability creates diverse reactive sites on perovskite surfaces, potentially boosting water-oxidation catalysis by increasing the number of active sites.

Contribution

It reveals that metastability induces a variety of reactive sites on perovskite surfaces, explaining enhanced water-oxidation activity and suggesting catalyst pre-treatment as a strategy for improved performance.

Findings

Large range of overpotentials across different sites

Metastability leads to diverse reactive sites

Pre-treatment can enhance catalytic activity

Abstract

While metastability enhanced water-oxidation activity was experimentally reported, the reason behind this effect is still unclear. We determine here, using density functional theory calculations, oxygen evolution reaction overpotentials for a variety of defective (001) surfaces of three different perovskite materials. For all three, we find a large range of overpotentials for different reaction sites including also overpotentials at the top of the activity volcano. Assuming that these sites dominate the apparent catalytic activity, this implies that a large number of geometrically different reaction sites, as they occur when a catalyst is operated at the border of its stability conditions, can lead to a strong enhancement of the apparent activity. This also implies that a pre-treatment of the catalyst creating a variety of different reactive sites could lead to superior catalytic activities for thermodynamically stable materials.