Cerium Surface-Engineered Iridium Oxides for Enhanced Oxygen Evolution Reaction Activity and Stability

Hierarchical assembly of materials has gained much attention recently due to their significant role in increasing the oxygen evolution reaction (OER) activity along with the reduction of noble-metal loading. However, the substrates are usually metal oxides that are hardly capable of withstanding harsh OER conditions. Therefore, at present, it remains a critical challenge to design more effective and robust catalyst-support materials. Here, we synthesized cerium-decorated iridium dioxide (IrO2) on the surface of alpha-MnO2 nanorods through a two-step hydrothermal process. The performed transmission electron microscopy (TEM), pore size distribution analysis, and electrochemical measurements confirmed that the growth of IrO2 and CeO2 nanoparticles well covered the surface of the substrate alpha-MnO2. Additionally, X-ray adsorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) analyses suggested Ce decoration causing lattice distortion in IrO2 and high 5d occupation, which resulted further in the OER activity enhancement. The specific mass activity of the prepared hybrid was found to be 5 times higher than that of IrO2 with excellent stability equivalent to that of non-Ce-modified catalyst. Thus, we demonstrate that surface engineering is a promising way to develop catalysts with more efficiency and robustness.