Corrosion and Alloy Engineering in Rational Design of High Current Density Electrodes for Efficient Water Splitting

Abstract

Alongside rare-earth metals, Ni, Fe, Co, Cu are some of the critical materials that will be in huge demand thanks to growth in clean-energy sector. Herein scrap stainless steel wires (SSW) from worn-out tires are employed as a support material for catalyst integration in the hydrogen evolution reaction (HER). In addition, SSW by corrosion engineering is exercised as an in situ formed freestanding robust electrode for the oxygen evolution reaction (OER). By superficial corrosion of SSW, inherent active species are unmasked in the form of Ni/FeOOH nanocrystallites displaying efficient water oxidation by reaching 500 mA cm(-2) at low overpotential (eta(500)) of 287 mV in 1 m KOH. Similarly, cathode scrap SSW with active (alloy) coatings of MoNi4 catalyzes the HER at eta(-200) = 77 mV, with a low activation energy (E-a = 16.338 kJ mol(-1)) and high durability of 150 h. Promisingly, when used in industrial conditions, 5 m KOH, 343 K, these electrodes demonstrate abnormal activity by yielding high anodic and cathodic current density of 1000 mA cm(-2) at eta = 233 mV and eta = 161 mV, respectively. This work may inspire researchers to explore and reutilize high-demand metals from scrap for addressing critical material shortfalls in clean-energy technologies.