Sarah Geo

• Petlund, Henrik; Geo, Sarah; Velluva, Abhijai; Pokle, Anuj & Chatzitakis, Athanasios (2025). nanoGe - MATSUSFall25 - The dual role of A-site deficiency in perovskite oxides: Exsolution of metal nanoparticles and suppression of surface amorphization. Fulltekst i vitenarkiv Vis sammendrag

  Catalysts enable important chemical transformations for industrial applications, as well as for emerging technologies for the decarbonization of our societies, such as water electrolysis and the production of green hydrogen. Very often, catalysts experience structural and compositional changes during operating conditions, most notably the oxygen evolution reaction (OER), that hinder their ratio...

• Geo, Sarah; Pokle, Anuj; Velluva, Abhijai; Dayaghi, Amir Masoud & Chatzitakis, Athanasios (2025). Suppressing surface amorphization in BSCF-based perovskites through A-site deficiency for use as anodes in water electrolysis. Fulltekst i vitenarkiv Vis sammendrag

  The development of efficient and stable anodes for water electrolysis is critical to advancing sustainable hydrogen production. Among perovskite oxides, BSCF82 (Ba₀.₅Sr₀.₅Co₀.₈Fe₀.₂O₃-δ) has emerged as a promising candidate due to its favourable balance of electronic conductivity, oxygen mobility, and catalytic activity. However, BSCF82 suffers from serious degradation during the oxygen evolution reaction (OER) process due to surface amorphization caused by the leeching of A-site ions (Ba²⁺ and Sr²⁺)​[1]​. Previously, we showed that A-site deficiency in Ba0.5Gd0.8La0.7Co2O6 can suppress it surface amorphization during OER activity and in the present study, we generalize this observation by employing a similar strategy in BSCF82​[2]​. By creating controlled A-site vacancies in the Ba₀.₅-xSr₀.₅-xCo₀.₈Fe₀.₂O₃-δ perovskite structure, we achieved improvement in its structural stability under OER conditions in 1 M KOH. High-resolution transmission electron microscopy revealed that A-site deficient compositions exhibited reduced surface amorphization and preserved crystalline surface structures after electrochemical testing in 1 M KOH. This work provides new insights into mitigating surface amorphization in perovskite catalysts through defect engineering and presents a promising strategy for developing durable electrocatalysts for renewable energy applications. Acknowledgements: This work has received financial support from the European Union HORIZON Research and Innovation Actions under grant agreement ID 101122323 (REFINE).

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