Perovskite oxides as oxygen catalysts

Abstract

Renewable energy resources will play a big role in the future of humanity because of global warming and environmental pollution. However, renewable energy needs to be coupled with energy storage systems. Water electrolyzers, which can convert the water to hydrogen using electricity, are considered as promising candidates for such task. However, the efficiency of current water electrolyzer is limited by the sluggish kinetics of the oxygen evolution reaction (OER) and the high cost of catalyst materials. Perovskite oxide with a general chemical formula of ABO₃ has demonstrated a promising performance as OER catalysts. In order to further improve the OER performance of perovskite to compete with state-of-art precious metal-based catalysts, we first studied La_0.8Sr_0.2CoO_3-δ (LSC) and tried to improve this material by subjecting it to multiple H₂O₂ treatments. After 4 treatments, the OER current density of LSC at 1.70 V (vs RHE) had a 6.6 folds improvement compared to the original one. The onset potential was found to be 1.47 V (vs RHE). The long-term stability also improved dramatically after treatment. All these enhancements are likely linked to the amorphous layer of hydrous oxide on the LSC particles. We also synthesized nanosize BaFeO_3-δ(BF) with a facile template-free method as a potential candidate as OER catalyst. The nano BF have a diameter ranging from 60-130nm and demonstrated much better stability than bulk BF.

Date of Award	2017
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology