High overpotentials, particularly an issue of common anode materials, hamper
the process of water electrolysis for clean energy generation. Thanks to
immense research efforts up to date oxygen evolution electrocatalysts based on
earth-abundant elements work efficiently and stably in neutral and alkaline
regimes. However, non-noble metal-based anode materials that can withstand low
pH regimes are considered to be an indispensable prerequisite for the water
splitting to succeed in the future. All oxygen evolving electrodes working
durably and actively in acids contain Ir at least as an additive. Due to its
scarcity and high acquisition costs noble elements like Pt, Ru and Ir need to
be replaced by earth abundant elements. We have evaluated a Ni containing
stainless steel for use as an oxygen-forming electrode in diluted H2SO4.
Unmodified Ni42 steel showed a significant weight loss after long term OER
polarization experiments. Moreover, a substantial loss of the OER performance
of the untreated steel specimen seen in linear sweep voltammetry measurements
turned out to be a serious issue. However, upon anodization in LiOH, Ni42 alloy
was rendered in OER electrocatalysts that exhibit under optimized synthesis
conditions stable overpotentials down to 445 mV for 10 mA cm-2 current density
at pH 0. Even more important: The resulting material has proven to be robust
upon long-term usage (weight loss: 20 mug/mm2 after 50 ks of
chronopotentiometry at pH 1) towards OER in H2SO4. Our results suggest that
electrochemical oxidation of Ni42 steel in LiOH (sample Ni42Li205) results in
the formation of a metal oxide containing outer zone that supports solution
route-based oxygen evolution in acidic regime accompanied by a good stability
of the catalyst.Comment: arXiv admin note: text overlap with arXiv:1712.0110
