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

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-Ba2CoMnO6−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 La2–x CoMnO6−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.

Charting Ba-Based Double Perovskite Oxides for Visible-Light-Driven Photocatalytic Water Splitting

“…reported a series of A -site perovskites and found that Ba 2.4 CoMoO 6 exhibited improved OER activity with a low overpotential (423 mV). Other reports also show that Ba 2+ -based − and -modified , perovskites are promising photocatalysts for water-splitting applications. Therefore, it is necessary to unveil other underlying physics of these compounds and explore viable Ba 2+ -based double perovskites for visible-light-driven photocatalysts.…”

B-Site Effect on High-Entropy Perovskite Oxide as a Bifunctional Electrocatalyst for Rechargeable Zinc–Air Batteries

“…Following these, the subsequent peaks are indicative of oxygen vacancies. The initial peak at approximately 531 eV corresponds to OH – or O 2 , , which assumes paramount significance in the OER and ORR. Particularly, OH – functions as a pivotal species in OER, facilitating an interaction with active metal sites and leading to the formation of oxyhydroxide species, subsequently driving O 2 evolution.…”

“…The HEPO samples were synthesized by the modified sol–gel Pechini method, as mentioned in our previous research . Subsequently, after drying, the single-phase high-entropy perovskite oxides were obtained rapidly via joule heating of the nickel foam.…”

“…The HEPO samples were synthesized by the modified sol−gel Pechini method, as mentioned in our previous research. 14 Subsequently, after drying, the single-phase high-entropy perovskite oxides were obtained rapidly via joule heating of the nickel foam. To facilitate the process, two crocodile clips were affixed to the nickel foam, which had dimensions of 5 cm × 2 cm × 0.2 mm and was shaped into a boat-like structure to conveniently accommodate the calcined powders.…”

“…Electrocatalytic oxygen reactions play an indispensable role in a diverse array of electrochemical technologies. − Due to the expensive cost, limited availability, and stability issues of platinum group electrocatalysts, there is a strong motivation to create catalysts that use affordable materials and exhibit high activity for industrial applications while also maintaining long-term durability. − However, achieving this goal remains challenging at the present stage. In this context, perovskite-type transition metal oxides (ABO 3 ) are fascinating because they show high effectiveness in promoting the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline conditions. − Additionally, their physical and electrochemical properties can be adjusted by introducing different elements into the A and B sites. , This ability to fine-tune the properties is crucial for enhancing the catalyst’s performance. To enhance the electrocatalytic properties of perovskite oxides, scientists have used defect engineering techniques, such as chemical doping − and adjusting the stoichiometry, , to modify their electronic structure ,− and physical characteristics. ,− For instance, Shen et al improved the OER activity by partially replacing La 3+ ions with Sr 2+ ions in LaCoO 3 .…”