In Situ Exsolved Mangosteen‐Type Nanoalloy Clusters and Engineered Heterogeneous Interfaces for High‐Performance Fuel‐Flexible Solid Oxide Cells

Abstract The development of high‐performance fuel electrodes exhibiting exceptional catalytic activity and fuel flexibility remains a critical challenge for advancing solid oxide cells (SOCs). However, current Ni‐YSZ cermet or oxide fuel electrodes suffer from either poor fuel flexibility or limited electrochemical activity. This study presents a novel strategy for creating heterogeneous interfaces through the first‐reported exsolution of mangosteen‐type FeRu nanoalloy clusters from Sr_1.9Fe_1.5Mo_0.43Ru_0.07O_6‐δ (Ru‐SFM0.07‐1.9) fuel electrodes. The combination of nanoalloy clusters, oxygen vacancies, and heterogeneous interfaces significantly enhances electrochemical activity by providing more catalytic sites and reducing the activation energy for C─H bond cleavage. Concurrently, the formation of oxygen vacancies improves resistance to carbon deposition and fuel flexibility. The SOC with Ru‐SFM0.07‐1.9 fuel electrode achieves peak power densities (P_max) of 1.79, 1.54, 1.36, and 1.13 W cm⁻² under H₂, naphtha, propane, and methane at 850 °C in fuel cell (FC) mode, respectively. While it exhibits current densities of 3.29 A cm⁻² under 1.6 V at 850 °C with CO₂ in electrolysis cell (EC) mode. These results demonstrate that the construction of heterogeneous interfaces by exsolution of nanoalloy clusters is a promising strategy to enhance both the electrochemical activity and fuel flexibility of SOCs.