Pr-Doped LaCoO₃ toward Stable and Efficient Oxygen Evolution Reaction

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, La_1–xPr_xCoO₃ 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 La_0.5Pr_0.5CoO₃ 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, La_0.5Pr_0.5CoO₃ showed more stable performance in long-term tests compared with Pr_0.5Ba_0.5CoO₃ and La_0.6Sr_0.4CoO₃. 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 La_0.5Pr_0.5CoO₃ 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.