Reactivity of Atomic Oxygen Radical Anions in Metal Oxide Clusters

Atomic oxygen radical anion (O⋅⁻) represents an important type of reactive centre that exists in both chemical and biological systems. Gas-phase atomic clusters can be studied under isolated and well controlled conditions. Studies of O⋅⁻-containing clusters in the gas-phase provide a unique strategy to interpret the chemistry of O⋅⁻ radicals at a strictly molecular level. This review summarizes the research progresses made since 2013 for the reactivity of O⋅⁻ radicals in the atomically precise metal oxide clusters including negatively charged, nanosized, and neutral heteronuclear metal clusters benefitting from the development of advanced experimental techniques. New electronic and geometric factors to control the reactivity and product selectivity of O⋅⁻ radicals under dark and photo-irradiation conditions have been revealed. The detailed mechanisms of O⋅⁻ generation have been discussed for the reaction systems of nanosized and heteroatom-doped metal oxide clusters. The catalytic reactions mediated by the O⋅⁻ radicals in metal clusters have also been successfully established and the microscopic mechanisms about the dynamic generation and depletion of O⋅⁻ radicals have been clearly understood. The studies of O⋅⁻ containing metal oxide clusters in the gas-phase provided new insights into the chemistry of reactive oxygen species in related condensed-phase systems.