Differentiated distribution of doped-iridium atoms for efficient acidic oxygen evolution

The development of proton exchange membrane water electrolyzers (PEMWEs) relies on the active and robust iridium (Ir)-based electrocatalysts for oxygen evolution reaction (OER) under acidic conditions. Loading low-content Ir with cobalt oxide (Co 3 O 4 ) nanocrystals has attracted considerable attention due to its reasonable price and high activity. However, their unsatisfying stability in acidic environments hinders their application. Herein, Ir atoms have been distributed differentiatedly in Co 3 O 4 to enhance the durability for acidic OER. Compared to the Co 3 O 4 with Ir uniformly doping (Ir B -Co 3 O 4 ), the reduced bulk Ir content in Ir S -Co 3 O 4 alleviates the electrooxidation process and facilitates the adsorbate-based pathway, thus stabilizing the structure of oxides during acidic OER. The optimized Ir S -Co 3 O 4 catalyst exhibits high mass activity of 1059.9 A g Ir −1 at 1.60 V vs RHE (779.6 A g Ir −1 for Ir B -Co 3 O 4 ). Importantly, Ir S -Co 3 O 4 possesses great stability without obvious activity loss after 20 h of continuous operation at 10 mA cm −2 , while the Ir B -Co 3 O 4 and Co 3 O 4 is deactivated within 8 and 4 h, respectively. This work provides a mechanistic understanding for designing lower-cost, active, and stable electrocatalysts containing a trace of Ir for OER.