Highly Efficient Oxygen Evolution Activity of Ca2IrO4 in an Acidic Environment due to Its CrystalConfiguration

摘要

We systematically characterized the perovskite-like oxides Ca2IrO4 and CaIrO3 as the oxygen evolution reaction (OER) catalysts. Compared with IrO2, universally accepted as the current state-of-the-art OER catalyst, Ca2IrO4 showed an excellent OER catalytic activity in an acidic environment, whereas CaIrO3 did not. X-ray photoelectron spectroscopy (XPS) spectra showed that the oxidation of iridium in Ca2IrO4 and CaIrO3 was slightly beyond +4. X-ray absorption near-edge structure (XANES) spectra illustrated that the IrO6 octahedral geometric structure in Ca2IrO4 and CaIrO3 showed differences. The IrO6 octahedral is asymmetrically distorted and uniformly compressed in Ca2IrO₄ and CaIrO₃. Therefore, we propose that the IrO₆ octahedral distortion plays an important role in the OER activities.