Homolytic H2O Dissociation into Hydroxyl and Hydrogen Radicals on Sulfur-Deficient Greigite for Efficient Hydration Reactions

Homolytic dissociation of ubiquitous water (H2O) into radical species is pivotal in driving reactions across chemical, biological, geoscientific, and environmental domains; yet, it faces substantial challenges in cleaving the robust O–H bond and preventing radical recombination. Herein, we demonstrate that greigite with sulfur vacancies (SVs) can ambiently dissociate H2O into reactive hydroxyl (•OH) and hydrogen (•H) radicals in a stoichiometric manner. This process is facilitated by the inverse-spinel structure of Fe3S4, where the antiparallel arrangement of high-spin Fe atoms localizes electrons at SVs, enabling barrierless cleavage of the O–H bond to yield •OH and •H. Concurrently, adjacent S atoms with pronounced Lewis basicity effectively stabilize the generated •H, promoting its spatial separation from the •OH confined on SVs. This interesting water homolysis scheme, characterized by synchronous •OH and •H generation, triggers efficient and selective hydrations of styrene and its derivatives to high-value-added aldehydes and energy-rich methane via a radical pathway.