Praseodymium iridium oxide as a competitive electrocatalyst for oxygen evolution reaction in acid media

Amorphous iridium oxides (IrO x ) are highly active for oxygen evolution reaction (OER) in acid media; however, it is generally unstable compared with commercial IrO 2 . Recently, many non-noble metal-iridium mixed oxides are prepared for catalyzing OER efficiently. Herein, we report a cubic fluorite-type praseodymium iridium oxide with the surface of IrO x (IrO x /Pr 3 IrO 7 ) that shows the improved activity and stability in 0.1 mol L −1 HClO 4 solution, characterized by an overpotential of 305 mV at the benchmark of 10 mA cm −2 and a small Tafel slope of 37 mV dec −1 , indicating a fast reaction kinetics and a competitive activity compared with the benchmark IrO 2 and most reported electrocatalysts. The initial potential increases by less than 0.07 V after continuous OER testing over 60,000 s. In contrast, IrO 2 becomes nearly inactive for the OER within 20,000 s. Density functional theory calculations uncover that the optimal energy level path follows lattice oxygen mechanism (LOM). This work enlarges the family of the IrO x -type OER electrocatalyst in acid media.