Zero-valent iron (ZVI) has demonstrated high potential for in-situ remediation of contaminated groundwater and soils. Upon exposure to oxygen, ZVI generates reactive oxygen species (ROS). In parallel with the electron transfer mediated-reductive path, ROS plays a critical role in the oxidative degradation of organic pollutants during ZVI remediation of groundwater and soil. Yet, the efficiency is often constrained by the confined ROS production localized to the surface or immediate vicinity of ZVI particles. Here, we demonstrate that quinones significantly enhance ROS production from ZVI over centimeter-scale distances. H₂O₂ and