Facile Synthesis and Origin of Enhanced Electrochemical Oxygen Evolution Reaction Performance of 2H-Hexagonal Ba2CoMnO6-δ as a New Member in Double Perovskite Oxides

Tuncay Erdil; Ersu Lokcu; Ilker Yildiz; Can Okuyucu; Yunus Eren Kalay; Cigdem Toparli

doi:10.1021/acsomega.2c05627

Facile Synthesis and Origin of Enhanced Electrochemical Oxygen Evolution Reaction Performance of 2H-Hexagonal Ba₂CoMnO_6-δ as a New Member in Double Perovskite Oxides

ACS Omega. 2022 Nov 21;7(48):44147-44155. doi: 10.1021/acsomega.2c05627. eCollection 2022 Dec 6.

Authors

Tuncay Erdil¹, Ersu Lokcu², Ilker Yildiz³, Can Okuyucu¹, Yunus Eren Kalay¹, Cigdem Toparli¹

Affiliations

¹ Department of Metallurgical and Materials Engineering, Middle East Technical University, 06800 Ankara, Turkey.
² Department of Metallurgical and Materials Engineering, Eskisehir Osmangazi University, 26040 Eskisehir, Turkey.
³ Central Laboratory, Middle East Technical University, 06800 Ankara, Turkey.

Abstract

Perovskite oxides have been considered promising oxygen evolution reaction (OER) electrocatalysts due to their high intrinsic activity. Yet, their poor long-term electrochemical and structural stability is still controversial. In this work, we apply an A-site management strategy to tune the activity and stability of a new hexagonal double perovskite oxide. We synthesized the previously inaccessible 2H-Ba₂CoMnO_6-δ (BCM) perovskite oxide via the universal sol-gel method followed by a novel air-quench method. The new 2H-BCM perovskite oxide exhibits outstanding OER activity with an overpotential of 288 mV at 10 mA cm^-2 and excellent long-term stability without segregation or structural change. To understand the origin of outstanding OER performance of BCM, we substitute divalent Ba with trivalent La at the A-site and investigate crystal and electronic structure change. Fermi level and valence band analysis presents a decline in the work function with the Ba amount, suggesting a structure-oxygen vacancy-work function-activity relationship for Ba _x La_2-x CoMnO_6-δ (x = 0, 0.5, 1, 1.5, 2) electrocatalysts. Our work suggests a novel production strategy to explore the single-phase new structures and develop enhanced OER catalysts.