Iodide Oxidation Reaction Catalyzed by Ruthenium–Tin Surface Alloy Oxide for Efficient Production of Hydrogen and Iodine Simultaneously

A new type of electrolysis by employing iodide oxidation reaction (IOR) via a ruthenium–tin surface alloy oxide (RuSn SAO) catalyst was designed to replace oxygen evolution reaction (OER) for efficient production of hydrogen, which not only enhances energy conversion efficiency but also produces a high-value commodity chemical, iodine, rather than O₂, in the anodic cell. Remarkably, the excellent activity of RuSn SAO enables it to be the best catalyst for IOR toward energy-saving hydrogen production. Its two-electrode acidic electrolyzer requires a cell voltage of only 1.07 V to afford 10 mA cm^–2, which is 0.51 V less than that required for OER to reach the same current density. Thus, the system drastically reduces energy consumption by more than 40% compared to pure water electrolysis. The chronopotentiometric test shows that the RuSn SAO needed a super-low overpotential increase of Δη = 70 mV at 10 mA cm^–2 together with recorded highly durable stability in the acidic electrolyte, indicating enhanced catalytic activity. Furthermore, this strategy simultaneously produces hydrogen with ∼100% Faradic efficiency and a high-value commodity chemical, I₂, making H₂ production potentially costless. Thus, the proposed concept paves a new way to facilitate the realization of hydrogen economics.