IrO<sub>2</sub>–ZnO Composite Nanorod Array as an Acid-Stable Electrocatalyst with Superior Activity for the Oxygen Evolution Reaction
Dasol Jin, Hyomin Yoo, Youngmi Lee, Chongmok Lee, Myung Hwa Kim
Abstract
An IrO2–ZnO composite nanorod array with distinct morphological features was successfully fabricated through a facile method via a simple acid–base reaction, followed by a postcalcination process. A modulation in the annealing treatment time (t) generated the variation in morphology, at a constant temperature (600 °C), and the nanorod-like growth on the surfaces was revealed at t ≥ 3 h. Especially, the IrO2–ZnO composite nanorod array exhibited superior OER catalytic activities (e.g., a potential of 1.481 V at 10 mA cm–2 (vs RHE) and a Tafel slope of 42.9 mV dec–1). Moreover, there was no apparent potential shift with robust long-term cycling stability under acidic conditions, which were much better than those of IrO2 and commercial iridium (cIr) and comparable with those of the previously reported outstanding Ir-based OER catalysts. Considering that the nanorod array was fabricated with the loading of the Zn metal component, which showed generally low catalytic activity and poor durability, this study suggests a promising strategy with an extended synthetic methodology for preparing Zn-mixed metal oxides as highly efficient electrocatalysts.