An iridium-based nanocomposite prepared from an iridium complex with a hydrocarbon-based ligand

Abstract

In this study, a chlorobis(cyclooctene)iridium(I) dimer (complex 1) with a simple hydrocarbon-based ligand is investigated as a precatalyst for the oxygen-evolution reaction in the presence of cerium(IV) ammonium nitrate (CAN) for the first time. The solid formed during the oxygen-evolution reaction is investigated by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction, oxygen meter, UV-Vis spectroscopy, X-ray photoelectron spectroscopy, and oxygen meter coupled to electronic spectroscopy. It is proposed that an iridium-oxide-based catalyst is at least one of the candidates of the true catalyst for the OER in the presence of CAN and complex 1. The catalyst contained Ir, Ce, C, N, and O. Thus, the candidate for the oxygen-evolving catalyst may not be a simple iridium oxide, as it is usually discussed in the literature. Electronic spectra of complex 1 and many previously reported iridium complexes in the presence of CAN, show peaks at 500–750 nm. It is hypothesized that a candidate for the oxygen-evolving catalyst for many Ir complexes is similar, and is an iridium oxide-based compound.