Scientific Achievement: This work showed that the rate of CO2 uptake by MgO slows over time and is limited by CO2 diffusion through the reacted layer.
Significance and Impact: MgO is a promising candidate material for direct air capture of CO2, but the rate of uptake and the controls on its reactivity are not known. The armoring effect shown here will need to be overcome to improve the economics of this inexpensive DAC method.
