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

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 Sr_1-α(Ti, Fe)O_₃-γ perovskites, an earth-abundant system with promising ionic-electronic conductivity and adequate oxygen vacancies, overcomes the limitations of traditional Sr(Ti, Fe)O₃ 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/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.