Timely-activated 316L stainless steel: A low cost, durable and active electrode for oxygen evolution reaction in concentrated alkaline environments

316 L stainless steel (SS) electrodes were activated for the oxygen evolution reaction (OER) without addition of hetero-elements or incorporation of deposits at their surface. Such activation was either spontaneous (in situ: slow surface modification upon OER operation), or accelerated (ex situ, by alternating potential steps at low/high potential). Both techniques enable formation of a catalytic surface from the SS bulk components in experimental conditions close to those of usage, which guarantees long-term-stability and high-activity of the surfaces. Ex situ-activated electrodes show comparable performances than in situ-activated electrodes, the resulting OER activities in KOH electrolytes being high compared to other noble-metal-free electrocatalysts. Activated 316 L electrodes are remarkably stable in long-term OER operation (> 300 h). Therefore, cheap and widely-available activated-SS may be very competitive OER materials for alkaline water electrolyzers. These results open the way to the development of highly-active and low-cost OER materials for hydrogen production, or metal-air batteries.