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Carbon Capture by Metal Oxides: Unleashing the Potential of the (111) Facet

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journal contribution
posted on 19.03.2018, 00:00 authored by Greg 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.

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