Out-of-plane coordination of iridium single atoms with organic molecules and cobalt-iron hydroxides to boost oxygen evolution reaction.

Advancements in single-atom-based catalysts are crucial for enhancing oxygen evolution reaction (OER) performance while reducing precious metal usage. A comprehensive understanding of underlying mechanisms will expedite this progress further. Here we report Ir single atoms coordinated out-of-plane with dimethylimidazole (MI) on CoFe hydroxide (Ir ₁ /(Co,Fe)-OH/MI). This Ir ₁ /(Co,Fe)-OH/MI catalyst, which was prepared using a simple immersion method, delivers ultralow overpotentials of 179 mV at a current density of 10 mA cm ^-2 and 257 mV at 600 mA cm ^-2 as well as an ultra-small Tafel slope of 24 mV dec ^-1 . Furthermore, Ir ₁ /(Co,Fe)-OH/MI has a total mass activity exceeding that of commercial IrO ₂ by a factor of 58.4. Ab initio simulations indicate that the coordination of MI leads to electron redistribution around the Ir sites. This causes a positive shift in the d-band centre at adjacent Ir and Co sites, facilitating an optimal energy pathway for OER.
(© 2024. The Author(s).)