Boron-doped amorphous iridium oxide with ultrahigh mass activity for acidic oxygen evolution reaction

Oxygen evolution reaction (OER), as the primary anodic reaction, plays a critical role in many electrochemical energy conversion processes. As the state-of-the-art OER catalysts, iridium-based materials are largely hindered from practical applications mainly due to the extreme scarcity of iridium. Here we demonstrate the successful fabrication of boron-doped amorphous iridium oxide (IrOx-B) via a facile boric acid-assisted method, which realizes an ultrahigh OER mass activity of 2779 A g Ir −1 at 300 mV overpotential, representing one of the best acidic OER catalysts reported so far. It is found that boric acid can not only facilitate the exposure of Ir, but also dope the amorphous IrOx with a form of metaborate, which could further modify the electronic and local ligand structure of Ir for the improved intrinsic activity. Interestingly, the reported strategy is universal that can be applied to improve other metal oxide OER catalysts, highlighting a versatile strategy for creating high-performance electro-catalysts with ultrahigh mass activity for OER and beyond.