# Copper nanoparticle exsolution from Sr(Ti, Fe)O3 perovskites: material tuning and probing (electro)catalytic applicability

## TL;DR

Researchers developed a new way to create copper nanoparticles on a perovskite material, which could improve electrocatalysts for energy reactions.

## Contribution

The study introduces a tunable perovskite system for controlled copper nanoparticle exsolution at low temperatures.

## Key findings

- Copper nanoparticles were exsolved from Sr0.95Ti0.3Fe0.7−xCuxO3−γ perovskites at as low as 400 °C.
- Nanoparticle size and density were controllably adjusted via reduction parameters.
- The material showed improved electrocatalytic performance for nitrate reduction.

## Abstract

Copper (Cu) is a recyclable, abundant, and promising catalyst for energy transition reactions like electrochemical conversion of nitrate (NO3RR) and CO2 electroreduction. However, conventional Cu-based electrocatalysts struggle with activity, selectivity, and durability, especially under harsh electrochemical conditions. Exsolution—the in situ generation of metallic nanoparticles on oxide supports in a single step—enables tightly anchored, size-controlled particles, enhancing stability and performance. Incorporating Cu into Sr1−α(Ti, Fe)O3−γ perovskites, an earth-abundant system with promising ionic–electronic conductivity and adequate oxygen vacancies, overcomes the limitations of traditional Sr(Ti, Fe)O3−γ in facilitating nanoparticle exsolution. This work demonstrates controlled Cu nanoparticle exsolution from Sr0.95Ti0.3Fe0.7−xCuxO3−γ perovskites at temperatures as low as 400 °C, notably milder than conventional exsolution conditions. By systematically varying reduction parameters, we achieve control over nanoparticle size (13–38 nm) and population density (118–650 particles per µm2). Electrochemical characterisation using nitrate reduction as a probe reaction demonstrates how exsolution conditions directly influence surface reactivity, establishing these materials as tuneable platforms for (electro)catalytic applications.

Sr0.95Ti0.3Fe0.6Cu0.1O3 perovskite shows enhanced reducibility and controlled Cu nanoparticles exsolution under reduction. Cu-doping tunes exsolution kinetics, particle density, and nitrate-reduction electrocatalytic response.