Emergence of Subsurface Oxygen on Rh(111)

Oxygen atoms on transition metal surfaces are highly mobile under the demanding pressures and temperatures typically employed for heterogeneously catalyzed oxidation reactions. This mobility allows for rapid surface diffusion of oxygen atoms, as well as absorption into the subsurface and reemergence to the surface, resulting in variable reactivity. Subsurface oxygen atoms play a unique role in the chemistry of oxidized metal catalysts, yet little is known about how subsurface oxygen is formed or returns to the surface. Furthermore, if oxygen diffusion between the surface and subsurface is mediated by defects, there will be localized changes in the surface chemistry due to the elevated oxygen concentration near the emergence sites. We observed that oxygen atoms emerge preferentially along the boundary between surface phases and that subsurface oxygen is depleted before the surface oxide decomposes.

Automated summary

This passage discusses the high mobility of oxygen atoms on transition metal surfaces under demanding pressures and temperatures, leading to rapid surface diffusion, absorption into the subsurface, and reemergence on the surface. The unique role of subsurface oxygen atoms in the chemistry of oxidized metal catalysts is highlighted, but little is known about their formation and return to the surface. Additionally, localized changes in surface chemistry can occur due to oxygen diffusion between the surface and subsurface being mediated by defects.