Direct dioxygen evolution in collisions of carbon dioxide with surfaces.

Abstract

The intramolecular conversion of CO₂ to molecular oxygen is an exotic reaction, rarely observed even with extreme optical or electronic excitation means. Here we show that this reaction occurs readily when CO₂ ions scatter from solid surfaces in a two-step sequential collision process at hyperthermal incidence energies. The produced O₂ is preferentially ionized by charge transfer from the surface over the predominant atomic oxygen product, leading to direct detection of both O₂⁺ and O₂^-. First-principles simulations of the collisional dynamics reveal that O₂ production proceeds via strongly-bent CO₂ configurations, without visiting other intermediates. Bent CO₂ provides dynamic access to the symmetric dissociation of CO₂ to C+O₂ with a calculated yield of 1 to 2% depending on molecular orientation. This unexpected collision-induced transformation of individual CO₂ molecules provides an accessible pathway for generating O₂ in astrophysical environments and may inspire plasma-driven electro- and photo-catalytic strategies for terrestrial CO₂ reduction.