Oxygen activation on Ba-containing perovskite materials

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Oxygen activation, crucial for energy conversion, involves complex reactions like the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
• The precise mechanism of oxygen activation in barium-containing perovskite materials remains unclear due to intricate four-electron transfer processes at gas-solid interfaces.

Purpose of the Study:

• To elucidate the role of barium oxides in oxygen activation within perovskite materials.
• To investigate the formation and decomposition of barium peroxide (BaO2) during oxygen activation.

Main Methods:

• Direct observation of surface species on Ba-containing materials.
• In-situ analysis of catalytic activity during ORR and OER.

Main Results:

• Barium oxide (BaO) and barium peroxide (BaO2) segregated on material surfaces were identified as active species in oxygen activation.
• Introducing barium oxides into perovskite and gold electrodes led to a tenfold increase in catalytic activity for ORR and OER.
• BaO and BaO2 demonstrated higher activity than the perovskite B-site for ORR and OER, respectively.

Conclusions:

• Barium oxides (BaO and BaO2) are critical for enhancing oxygen activation in perovskite materials.
• The formation and decomposition of BaO2 are central to the observed catalytic activity.
• These findings provide a new understanding of oxygen activation mechanisms in energy conversion systems.