Dissolution of nanoparticulate IrO₂ in dilute acidic baths through a pre-reduction step: A method to recover Ir from electrocatalytic/catalytic bodies

We report a process for recycling Ir-based nanosized electrocatalysts through dissolution of Ir under mild conditions (in dilute acidic media at ∼100 °C) and show that otherwise corrosion-resistant Ir-Oxide nanoparticles may be activated for dissolution in dilute HCl using a pre-reduction step. Effects of the reaction parameters such as the type of reducing agent, dissolution bath composition, reaction temperature, etc. was investigated. Further, structural characterizations to investigate the effect of the prereduction step on the Ir-Oxide and on the dissolved Ir species were made. The dissolved Ir was processed further to synthesize a new Ir-Oxide electrocatalyst exhibiting electrochemical performance (mass activity for oxygen evolution reaction) similar to that of the commercial Ir-Oxide. The study provides a recycling solution for the Ir-based electrocatalysts from relevant catalytic bodies and may be used for achieving sustainable acidic electrolyzers.