I'm wondering if anyone knows any experimental scenarios where the reaction order for the HER is 0.5 (vs. pH.), either acidic or alkaline environments. It is very common to see values like 1, 1.5, and even 2, but have you seen 0.5 anywhere?
Thank you for you response. I am aware of the theoretical possibility of non-stoichiometeric reaction orders (e.g. 0.5). What I'm looking for is if anyone have experimentally observed 0.5 vs. PH for the HER, and if so, what was the electrode material/electrolyte composition.