posted on 2018-03-19, 00:00authored byGreg A. Mutch, Sarah Shulda, Alan J. McCue, Martin J. Menart, Cristian V. Ciobanu, Chilan Ngo, James A. Anderson, Ryan M. Richards, David Vega-Maza
Solid metal oxides for carbon capture
exhibit reduced adsorption
capacity following high-temperature exposure, due to surface area
reduction by sintering. Furthermore, only low-coordinate corner/edge
sites on the thermodynamically stable (100) facet display favorable
binding toward CO2, providing inherently low capacity.
The (111) facet, however, exhibits a high concentration of low-coordinate
sites. In this work, MgO(111) nanosheets displayed high capacity for
CO2, as well as a ∼65% increase in capacity despite
a ∼30% reduction in surface area following sintering (0.77
mmol g–1 @ 227 m2 g–1 vs 1.28 mmol g–1 @ 154 m2 g–1). These results, unique to MgO(111), suggest intrinsic differences
in the effects of sintering on basic site retention. Spectroscopic
and computational investigations provided a new structure–activity
insight: the importance of high-temperature activation to unleash
the capacity of the polar (111) facet of MgO. In summary, we present
the first example of a faceted sorbent for carbon capture and challenge
the assumption that sintering is necessarily a negative process; here
we leverage high-temperature conditions for facet-dependent surface
activation.