Insight on Strain Relaxation Effect in Perovskites for High‐Temperature Hydrogen Oxidation Reaction

Abstract The size of in situ exsolved nanoparticles (NPs) significantly affects the electrochemical and electro‐catalytic properties of oxide supports. Unfortunately, the instrumental factor affecting the exsolved NP size in poly‐crystalline perovskite oxides is still unexplored. Herein, the inherent micro‐strain (ε) value as an unprecedented factor in controlling the exsolved NP size of Pr 0.5 Ba 0.5‐ x Sr x Fe 0.85 Ni 0.15 O 3‐ δ ( x = 0.3, 0.4, and 0.5) is introduced, wherein smaller NP size is successfully obtained via strain relaxation strategy. The effect of exsolved NP size on the fuel oxidation reaction kinetics at high‐temperature regimes is evaluated in‐depth by using density functional theory (DFT) calculations. In accordance with the insights provided by DFT calculations, the electro‐catalyst featuring the smallest Fe 3 Ni NP size via strain relaxation strategy demonstrates exceptional electrochemical performance along with robust durability toward high‐temperature hydrogen oxidation reaction. This work presents scientific guidance for tailoring the exsolved NP size in perovskites, thereby paving the way for designing rational perovskite electro‐catalysts in various energy‐related applications.