Iridium-Doped 10H-Phase Perovskite BaCo_0.8Fe_0.15Ir_0.05O_3–δ as an Efficient Oxygen Evolution Reaction Catalyst

Designing low-cost and high-performance catalysts of electrocatalytic oxygen evolution reaction (OER) has always been one of the hot topics in current research. Hexagonal perovskite materials show great application potential in this field. Here, we synthesized 5% Iridium (Ir)-doped hexagonal phase perovskite BaCo_0.8Fe_0.15Ir_0.05O_3–δ (BCFI). Using the Rietveld method to refine the structure, combining with the spherical aberration corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) atomic imaging, we found that BCFI is a ten-layer hexagonal (10H) structure, which belongs to the P (Formula presented.) m2 space group. In addition, BCFI shows excellent OER catalytic effect and good stability in 1 mol/L KOH solution, and the overpotential reaches 294 mV at a current density of 10 mA cm^–2. The reduction of Cobalt (Co) valence state induced by Ir doping significantly enhances the OER activity of BCFI. Meanwhile, density functional theory (DFT) calculations show that the 2p-band center of oxygen (O) in BCFI is closer to the Fermi level than that in undoped BaCo_0.8Fe_0.2O_3-δ (BCF), which is beneficial to the OER. This work reveals a novel 10H-BCFI material with excellent OER performance, and provides a basis for the design of hexagonal perovskite materials in OER and other energy conversion fields.