(687c) Design Strategies for Efficient Perovskite Oxide Electrocatalysts: Extending Concepts from Thermal Catalysis to Describe Their Electrocatalytic Performance

Renewed interest in the use of perovskite oxides as catalysts towards oxygen related electrochemical transformations has led to the need for identification of robust design criteria to tune their performance.^1,2 The existing paradigm for describing the activity of perovskite oxides often relies on the averaged oxidation state of the transition metal, which fails to comprehensively describe their activity.¹ Further, these design strategies rarely describe their stability. Consequently, development of rigorous design criteria, using measurable properties of working, non-model oxides which can shed light on their activity and stability remains an open challenge.

Herein, an approach to correlate experimentally measurable oxide properties (i.e., oxide surface reducibility) with their electrocatalytic activity and stability is developed.^2,3 This is demonstrated for electrochemical oxygen reduction reaction (ORR). We show that the oxide surface reducibility (E_VO), which describes the strength of the transition metal-lattice oxygen bond, captures effects from both the oxide composition and crystal symmetry, on the binding energetics of oxygenated intermediates, and consequently their ORR activity. E_VO is estimated empirically on working oxides using H₂-temperature programmed reduction studies, which exhibits a volcano type relationship with the empirically measured ORR activity.³ A correlation between E_VO and the stability of these oxides is also found, making this descriptor comprehensive in describing the overall performance of perovskite oxides.³ Extension of this descriptor towards predicting their performance for oxygen evolution reaction will be discussed.⁴ These insights open avenues for engineering active and stable cationic centers in complex oxides for targeted reaction chemistries.

References

(1) Gu, X-K.; Samira, S.; Nikolla, E. Chem. Mater. 2018, 30, 2860-2872.

(2) Samira, S.; Camayang, J.; Gu, X-K; Nikolla, E., ACS Energy Lett. 2021, 6, 1065-1072.

(3) Samira, S.; Gu, X-K.; Nikolla, E. ACS Catal. 2019, 9, 10575-10586.

(4) Samira, S.; Hong, J.; Camayang, J.; Bare, S.; Nikolla, E. JACS Au 2021, 1, 2224-2241.