  The use of proton exchange membrane (PEM) electrolyzers is the method of
choice for the conversion of solar energy when frequently occurring changes of
the current load are an issue. However, this technique requires electrolytes
with low pH. All oxygen evolving electrodes working durably and actively in
acids contain IrOx. Due to their scarcity and high acquisition costs, noble
elements like Pt, Ru and Ir need to be replaced by earth abundant elements. We
have evaluated a cobalt containing steel for use as an oxygen-forming electrode
in H2SO4. We found that the dissolving of ingredients out of the steel
electrode at oxidative potential in sulfuric acid, which is a well-known,
serious issue, can be substantially reduced when the steel is electro-oxidized
in LiOH prior to electrocatalysis. Under optimized synthesis conditions a
cobalt-containing tool steel was rendered into a durable oxygen evolution
reaction (OER) electrocatalyst (weight loss: 39 mug mm-2 after 50 000 s of
chronopotentiometry at pH 1) that exhibits overpotentials down to 574 mV at 10
mA cm-2 current density at pH 1. Focused ion beam SEM FIB-SEM) was successfully
used to create a structure-stability relationship.
