Considering the growing attention to oxygen evolution reaction (OER) as a key role in clean energy through electrocatalytic water splitting, advanced materials for water oxidation are central to the area of renewable energy. In general, the OER process, involved four electron and four proton coupled electrochemical reaction, demands higher kinetics to overcome an overpotential than HER (hydrogen evolution reaction). For this aspect, significant research efforts have been devoted to developing efficient OER electrocatalyst with enhanced electrocatalytic kinetics and long-term durability.

Here we present the synthetic processes and physical/electrochemical characterization of Cr_xIr_1-xO₂ nanotubes (NTs). Those NTs are synthesized through electrospinning, a simple way to facilitate 1D nanostructure, and post-thermal annealing process with different annealing speed (°C /min). As-prepared Cr_xIr_1-xO₂ NTs at the optimized conditions have shown outstanding OER electrocatalytic activity in alkaline media from the viewpoints of overpotential and Tafel slope as well as durability. The morphology and compositions of Cr_xIr_1-xO₂ were characterized by a field emission scanning electron microscope (FESEM) equipped with an energy dispersive X-ray spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The crystalline structures of the prepared Cr_xIr_1-xO₂ are investigated through high-resolution X-ray diffraction (XRD). Electrochemical activities for oxygen evolution reaction (OER) are studied with rotating disk electrode (RDE) voltammetry in N₂-saturated 1.0 M KOH (aq); and compared with those of iridium single component oxides (IrO_x and IrO₂) and commercial iridium (cIr, counterparts in OER electrocatalysts).

This work was financially supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT or by the Ministry of Education (NRF-2019R1F1A1059969, NRF-2018R1A6A1A03025340, NRF-2020R1A2B5B01001984, and NRF-2019R1F1A1062799).