Trace Chlorine-Induced Lattice Oxygen Activation for Enhanced High-Temperature CO<sub>2</sub> Electrolysis.
basic_science · Level V
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- Record sourced from PubMed, PMID 41231004.
- Also identified by DOI 10.1002/adma.202518116.
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Abstract
Tuning lattice oxygen activity in perovskite oxides (ABO<sub>3</sub>) offers a promising approach to overcome the intrinsic trade-off between catalytic activity and stability in redox reactions. However, precise modulation and mechanistic understanding of lattice oxygen activation remain elusive under high-temperature CO<sub>2</sub> electrolysis conditions. Herein, a novel anion activation strategy is proposed by incorporating trace chloride ions (Cl<sup>-</sup>) into the O-sites of Sr<sub>2</sub>Fe<sub>1.5</sub>Mo<sub>0.5</sub>O<sub>6-δ</sub> perovskite forming an oxychloride cathode. This Cl<sup>-</sup> substitution activates lattice oxygen reactivity by weakening Mo-O/Fe-O covalency, thereby facilitating the formation and redistribution of oxygen vacancies, accelerating bulk oxygen ion transport, enhancing CO<sub>2</sub> adsorption and carbonate intermediate formation, and ultimately promoting CO<sub>2</sub> reduction kinetics. As a result, the oxychloride cathode achieves a 60.2-80.8% enhancement in CO<sub>2</sub>-to-CO electrolysis, reaching 2.02 A cm<sup>-2</sup> at 800 °C and 1.5 V with ≈100% Faradaic efficiency, while maintaining exceptional stability of 500 h. This work establishes a new paradigm of O-site anion engineering to unlock lattice oxygen activity for electrocatalytic reactions.