IrO₂–ZnO Hybrid Nanoparticles as Highly Efficient Trifunctional Electrocatalysts

Development of high-performance catalysts is very crucial for the commercialization of sustainable energy conversion technologies. Searching for stable, highly active, and low-cost multifunctional catalysts has become a critical issue. In this study, we report the synthesis of IrO 2 –ZnO hybrid nanoparticles and their highly efficient electrocatalytic activities toward oxygen/hydrogen evolution reaction (OER/HER) as well as oxygen reduction reaction (ORR). For comparison, we synthesized RuO 2 –ZnO, showing a smaller catalytic activity than IrO 2 –ZnO, which provides robust evidence for the unique synergic effect of these hybrid structures. IrO 2 –ZnO and RuO 2 –ZnO exhibit excellent OER catalytic performance with Tafel slopes of 57 and 59 mV decade –1, respectively. For HER, IrO 2 –ZnO shows a higher catalytic activity than RuO 2 –ZnO. The numbers of electrons involved in the ORR were 3.7 and 2.8, respectively, for IrO 2 –ZnO and RuO 2 –ZnO. The remarkable catalytic performance of IrO 2 –ZnO would be ascribed to the abundant oxygen vacancies and the metallic states of Ir, which ensure excellent catalytic activity and stability.