Pr-Doped LaCoO₃ toward Stable and Efficient Oxygen Evolution Reaction

Abstract

Developing inexpensive, efficient, and stable electrocatalysts for oxygen evolution reaction (OER) is crucial in energy conversion devices. The high cost and insufficient stability of the state-of-the-art IrO2 electrocatalysts for OER have restricted their widespread applications. In this work, La1–xPrxCoO3 perovskites with different Pr doping concentrations (x = 0, 0.25, 0.5, 0.75, 1) were investigated as alternative and inexpensive OER electrocatalysts. The OER activity was observed to increase with Pr doping and was maximum at the 50 mol % doping concentration. The overpotential of La0.5Pr0.5CoO3 was reduced to 312 mV at 10 mA·cm–2, which was significantly smaller than 371 mV of LCO and even superior to that of the commercial IrO2 catalysts (341 mV). Furthermore, La0.5Pr0.5CoO3 showed more stable performance in long-term tests compared with Pr0.5Ba0.5CoO3 and La0.6Sr0.4CoO3. X-ray diffraction analysis showed phase transition from a rhombohedral to an orthorhombic structure with Pr doping. Based on X-ray photoelectron spectrum analysis, the enhanced OER activity of La0.5Pr0.5CoO3 was correlated to electron occupation close to the Fermi level and the hybridization of O 2p and Co 3d bands, which facilitated the electron transfer process of the OER. Our work is therefore expected to provide a facile method of designing high-performance and stable OER perovskite catalysts through an approach based on electronic occupation regulation.