Entangled iodine and hydrogen peroxide formation in ice

Abstract

Ice-core records show that anthropogenic pollution has increased the global atmospheric concentrations of hydrogen peroxide and iodine since the mid-20th century. Here, for the first time, we demonstrate a highly efficient mechanism that synergistically produces them in icy water conditions. This reaction is aided by a key intermediate IO₂H, formed by an I⁻ ion with a dissolved O₂ in acidic icy water, which produces both I as well as O₂H radicals. I recombines with I⁻ to produce I₂⁻ at a diffusion-limited rate, followed by formation of I₃⁻ through disproportionation, while O₂H yields H₂O₂ with I⁻ and a proton dissolved in icy water.