Revealing the reactivity of the Iridium trioxide intermediate for the oxygen evolution reaction in acidic media

29 April 2019, Version 1


We report a strategy to isolate IrO3 as an intermediate for the oxygen evolution reaction (OER). Its reactivity is studied using X-ray absorption spectroscopy, X-ray and neutron diffraction and X-ray photoelectron spectroscopy. Its stability is assessed by using on-line mass spectroscopy and inductively coupled plasma optical emission spectroscopy and presented herein. Upon reaction with water in acidic conditions, we could observe the formation of a new protonated iridate phase of composition H2IrO3. Coupling OER measurements and dissolution rate determination, we could show that its activity and stability are governed by a yet ill-described charge compensation mechanism enlisting reversible bulk proton insertion inside the catalyst structure. This singular property enables an enhanced activity and stability towards dissolution compared to the stellar IrOx/SrIrO3 catalyst. Such a finding opens the route towards the design of new OER catalysts enlisting proton insertion that could be competitive for water splitting in acidic media.


electrocatalysis applications
oxygen evolution reaction
proton insertion
Iridium trioxide

Supplementary materials

Pearce et al - SI - ChemRxiv


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.