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

Abstract

Comprehensive Summary 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 BaCo0.8Fe0.15Ir0.05O3–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 true 6¯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 BaCo0.8Fe0.2O3‐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.

Free‐Standing Multiscale Porous High Entropy NiFeCoZn Alloy as the Highly Active Bifunctional Electrocatalyst for Alkaline Water Splitting

“…[ 32 ] Beside the satellite peak at 715.5 and 725.1 eV, the peaks at 712.4 and 723.0 eV belong to Fe 3+ . [ 19,35 ] The splitted peaks unveal the existence of Fe oxide and hydroxide. As shown in Figure 4g, the peaks at 777.8 and 795.8 eV correspond to the 2p 3/2 and 2p 1/2 peaks of metallic Co. [ 36‐37 ] In addition, the peaks at 780.5 and 796.4 eV along with 783.3 and 798.0 eV can be ascribed to the 2p 3/2 and 2p 1/2 peaks for the Co 3+ and Co 2+ , respectively, [ 38 ] indicating the coexistence of metallic Co and high‐valence Co.…”

Noble Metal Phosphides Supported on CoNi Metaphosphate for Efficient Overall Water Splitting

“…In Ir 4f spectra (Figure 1f), the two peaks located at 61.2 and 64.0 eV are assigned to the Ir 4f 7/2 and Ir 4f 5/2 peaks of metallic Ir. 50,51 Besides, the strong shoulder peaks at 62.3 and 65.2 eV are attributed to the Ir−O species, 52 which may be caused by the strong metal support interaction or oxidation of Ir surface. 53 As shown in Figure 1g, it can be concluded that Co 2+ and Ni 2+ species exist in all of the samples because of the CoNiP 4 O 12 support.…”

Surface/Interface Engineering of Hierarchical MoO2/MoNi4@Ru/RuO2 Heterogeneous Nanosheet Arrays for Alkaline Water Electrolysis with Fast Kinetics

“…It is worth noticing that the optimized electronic and structural electrocatalysts are required to overcome the energy barrier of water dissociation and accelerate OH ad transfer in alkaline water splitting. [ 16‐19 ] MoNi 4 ‐based electrocatalyst is a promising candidate for HER and OER due to their easily tuned electronic structure and high conductivity. [ 20‐21 ] Furthermore, various strategies (such as morphology engineering, defect engineering, heterostructure engineering, etc .)…”