Steel-based electrocatalysts for efficient and durable oxygen evolution in acidic media

Abstract

2High 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 H 2 SO 4 . 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 µg/mm 2 after 50 ks of chronopotentiometry at pH 1) towards OER in H 2 SO 4 . 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.3

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

“…Recently Schäfer and Chatenet showed that surfacemodified (stainless) steel can be used as water splitting electrodes. [14] The approaches shown by Chatenet et al [15] and Schäfer et al [16][17][18][19] and by some of other groups are taking advantage of the elements contained in steel like Fe, Ni and Co, known for their sophisticated properties (at least) towards the electrocatalytically-initiated OER. However, scientists failed, likely owing to the absence of noble ingredients, in rendering steel at least as active towards the HER as Pt is.…”

Free‐Sustaining Three‐Dimensional S235 Steel‐Based Porous Electrocatalyst for Highly Efficient and Durable Oxygen Evolution

“…substantially.T ot he besto fo ur knowledge, some of our group were the first to tailor steel intentionally into outstanding,e fficient, and stable OER electrocatalysts [56][57][58] on the basis of, inter alia, thin Ni, Fe oxide layers firmly attachedt ot he iron-based matrix. Benchmark OER properties were showna tp H13a nd pH 14, as the overpotential (h)a mounted to 212 mV at 12 mA cm À2 in 1 m KOH and to 269.2 mV at 10 mA cm À2 in 0.1 m KOH, respectively.V ery recently,h ydrothermal/electrochemicalo xidation of CrNi-based steel [59] as well as the surface oxidation of Ni42 [60] and X20CoCrWMo10-9//Co 3 O 4 steel [57,61] also provedt ob es uitable for the efficient preparation of acceptable OER catalysts that weres table and workedo ver a wide pH range.…”

From Bad Electrochemical Practices to an Environmental and Waste Reducing Approach for the Generation of Active Hydrogen Evolving Electrodes

“…The approaches shown by Chatenet et al . and Schäfer et al . and by some of other groups are taking advantage of the elements contained in steel like Fe, Ni and Co, known for their sophisticated properties (at least) towards the electrocatalytically‐initiated OER.…”