Solid oxide electrolysis cells (SOECs) offer a route for efficient energy conversion and storage by converting renewable electricity into storable chemical fuels through high-temperature carbon dioxide electrolysis. However, sluggish oxygen evolution reaction (OER) at the anode poses a challenge due to its complex four-electron transfer process.
Perovskite oxides are regarded as promising candidates for SOEC anodes due to their high mixed ionic-electronic conductivity and tunable electronic structures. Studies have revealed a volcano-shaped correlation between the occupancy of the 3 d electron with e g symmetry in perovskite oxide and intrinsic OER activity in alkaline solution. However, the intrinsic connection between e g occupancy and high-temperature OER activity remains unclear.
In a study published in Journal of the American Chemical Society , Assoc. Prof. SONG Yuefeng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences, along with Prof. WANG Guoxiong from Fudan University, developed a series of alkaline-earth-metal-doped perovskites, Pr 0.5 Ae 0.5 FeO 3−δ (Ae = Ca, Sr, Ba, labeled as PCF, PSF, PBF), to investigate the impact of electronic structure tuning on high-temperature OER performance.
Researchers found that the OER activity increased with larger dopant ionic radius. They showed that the PBF achieved a current density of 3.33 A cm −2 at 2.0 V and 800 °C.
Detailed analyses revealed that alkaline earth metal doping enhanced Fe 3d-O 2p hybridization, lowered charge-transfer energy, and promoted oxygen ions migration and surface spillover, accelerating the OER process. Moreover, magnetic measurements showed that Ba doping induced a spin-state transition from high-spin Fe 3+ (t 2g 3 e g 2 ) to low-spin Fe 4+ (t 2g 4 e g 0 ), resulting in reduced e g occupancy and accelerated 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," said Dr. SONG.
Journal of the American Chemical Society
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Spin-State Tuning in PrFeO3-δ Perovskite for High-Temperature Oxygen Evolution Reaction
26-Aug-2025