Surface‐Engineered LSCF Electrode via PrNi 0.7 Co 0.3 O 3–δ Infiltration for Superior Performance and Stability in Reversible Protonic Ceramic Cells

The reversible protonic ceramic cells (R‐PCCs) have been extensively researched for power generation and hydrogen production at low and intermediate temperatures. However, sluggish kinetics of the air electrode at low temperatures, coupled with the lack of durability under high steam environments, hinder commercialization. In this work, we developed an air electrode with high catalytic activity and durability by surface‐modifying conventional La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3‐δ (LSCF) using single‐layer perovskite PrNi 0.7 Co 0.3 O 3‐δ (PNC‐73) through solution infiltration. PNC‐73 is a triple‐conducting oxide (TCO) that extends proton conduction paths from the triple‐phase boundary (TPB) to the bulk surface, unlike conventional air electrodes. Additionally, PrO 2 phase formation during infiltration creates oxygen vacancies, improving catalytic activity. PNC‐73‐coated LSCF exhibited a polarization resistance ( R p ) of 0.30 Ω . cm 2 at 650°C under both dry/humidified conditions, four times lower than the bare LSC. Furthermore, the infiltration reduced the degradation rate to 6.5 × 10 −4 Ω·cm 2 ·h −1 , nearly half that of bare LSCF (12.1 × 10 −4 Ω·cm 2 ·h −1 ) under a 30 v.% H 2 O environment at 650°C. The single cell (Ni‐BZCYYb/BZCYYb/LSCF‐PNC‐73) demonstrated a power density of 500 mW·cm −2 at 700°C in fuel cell mode and a current density of 2.80 A·cm −2 at 1.3 V in electrolysis mode, higher than bare LSCF air electrodes. This research provides direction to mitigate major conventional air electrodes issues in R‐PCCs, highlighting commercial viability.