Steel: The Resurrection of a Forgotten Water-Splitting Catalyst

Because of the limited availability of fossil fuels, the splitting of water into oxygen and hydrogen upon exploitation of solar energy becomes an increasingly important clean energy production and storage technique. Despite its early use as a hydrogen-evolution catalyst in alkaline electrolysis, steel was until very recently supposed to be neither an active and stable water-splitting catalyst nor an interesting scientific subject at all. The authors of this contribution not only have shown in recent papers the potential of steel in terms of pure material properties but also have revealed the qualities of steel as a striking scientific topic. They herewith review what is known about the water-splitting properties of untreated and surface-modified steel and try to determine a potential transfer to a broader application of modified steels in heterogeneous catalysis. The synopsis is basically limited to the usage of steel as a real electrocatalyst, thus presenting the catalytic active species itself.