Spin-State Tuning Dramatically Boosts Oxygen Evolution in High-Temperature electrolysis
DALIAN, CHINA – September 4, 2025 – Researchers at the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences, in collaboration with fudan University, have achieved a significant breakthrough in solid oxide electrolysis cell (SOEC) technology by demonstrating a method to substantially enhance the oxygen evolution reaction (OER) – a critical bottleneck in converting renewable energy into storable chemical fuels. The team’s work, published in the Journal of the American chemical Society, centers on “spin-state tuning” within perovskite oxide materials to accelerate OER performance at high temperatures.
SOECs offer a promising pathway for large-scale energy storage by using electricity to split carbon dioxide and water into hydrogen and oxygen. Though, the sluggish OER at the anode limits the efficiency of this process. Perovskite oxides have long been considered potential anode materials due to their conductive properties and adaptable electronic structures. Previous research indicated a link between the occupancy of 3d electrons with eg symmetry and OER activity in alkaline solutions, but the mechanism at the high temperatures crucial for SOEC operation remained unclear.
To address this, Assoc. Prof. SONG Yuefeng of DICP and Prof. WANG Guoxiong of Fudan University developed a series of perovskites – pr0.5Ae0.5FeO3−δ (were Ae represents calcium, strontium, or barium, labeled PCF, PSF, and PBF respectively) – and systematically investigated the impact of alkaline-earth-metal doping on OER performance.
Their findings revealed that increasing the ionic radius of the dopant significantly improved OER activity. Notably,the barium-doped perovskite (PBF) achieved a current density of 3.33 A cm−2 at 2.0 V and 800 °C.
Detailed analysis showed that doping with alkaline earth metals strengthens the interaction between iron 3d and oxygen 2p orbitals, lowers the energy required for charge transfer, and facilitates both oxygen ion migration and surface spillover – all contributing to a faster OER process. crucially, magnetic measurements demonstrated that barium doping induces a spin-state transition in the iron ions, shifting them from a high-spin Fe3+ (t2g3eg2) configuration to a low-spin fe4+ (t2g4eg0) state, thereby reducing eg occupancy and accelerating oxygen kinetics.
“Our study establishes spin-state tuning as a key strategy to boost high-temperature OER activity, and provides guidance for electronic structure engineering in the design of advanced SOEC anode materials,” explained Dr. SONG. This research offers a new direction for designing more efficient and cost-effective SOEC systems, perhaps accelerating the widespread adoption of renewable energy storage solutions.
