Direct dioxygen evolution in collisions of carbon dioxide with surfaces

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 O-2 is preferentially ionized by charge transfer from the surface over the predominant atomic oxygen product, leading to direct detection of both O-2+ and O-2- . First-principles simulations of the collisional dynamics reveal that O-2 production proceeds via strongly-bent CO2 configurations, without visiting other intermediates. Bent CO2 provides dynamic access to the symmetric dissociation of CO2 to C+O-2 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 O-2 in astrophysical environments and may inspire plasmadriven electro- and photo-catalytic strategies for terrestrial CO2 reduction.