Runaway Carbon Dioxide Conversion Leads to Enhanced Uptake in a Nanohybrid Form of Porous Magnesium Borohydride

Sohee Jeong; Phillip J Milner; Liwen F Wan; Yi-Sheng Liu; Julia Oktawiec; Edmond W Zaia; Alexander C Forse; Noemi Leick; Thomas Gennett; Jinghua Guo; David Prendergast; Jeffrey R Long; Jeffrey J Urban

doi:10.1002/adma.201904252

Runaway Carbon Dioxide Conversion Leads to Enhanced Uptake in a Nanohybrid Form of Porous Magnesium Borohydride

Adv Mater. 2019 Nov;31(44):e1904252. doi: 10.1002/adma.201904252. Epub 2019 Sep 20.

Authors

Sohee Jeong¹, Phillip J Milner^{2

3

4}, Liwen F Wan^{1

5}, Yi-Sheng Liu⁶, Julia Oktawiec^{2

3}, Edmond W Zaia¹, Alexander C Forse², Noemi Leick⁷, Thomas Gennett^{7

8}, Jinghua Guo^{6

9}, David Prendergast¹, Jeffrey R Long^{2

3

10}, Jeffrey J Urban¹

Affiliations

¹ The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
² Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
³ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
⁴ Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
⁵ Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA.
⁶ The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
⁷ National Renewable Energy Laboratory Colorado, Colorado, CO, 80401, USA.
⁸ Chemistry Department, Colorado School of Mines, 1012 14th Street, Golden, CO, 80401, USA.
⁹ Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA, 95064, USA.
¹⁰ Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA.

Abstract

Leveraging molecular-level controls to enhance CO₂ capture in solid-state materials has received tremendous attention in recent years. Here, a new class of hybrid nanomaterials constructed from intrinsically porous γ-Mg(BH₄ )₂ nanocrystals and reduced graphene oxide (MBHg) is described. These nanomaterials exhibit kinetically controlled, irreversible CO₂ uptake profiles with high uptake capacities (>19.9 mmol g^-1 ) at low partial pressures and temperatures between 40 and 100 °C. Systematic experiments and first-principles calculations reveal the mechanism of reaction between CO₂ and MBHg and unveil the role of chemically activated, metastable (BH₃ -HCOO)^- centers that display more thermodynamically favorable reaction and potentially faster reaction kinetics than the parent BH₄ ^- centers. Overall, it is demonstrated that size reduction to the nanoscale regime and the generation of reactive, metastable intermediates improve the CO₂ uptake properties in metal borohydride nanomaterials.

Keywords: carbon dioxide capture; kinetics; magnesium borohydride gamma phase (γ-Mg(BH 4)2); nanomaterials; reduced graphene oxide.

Abstract

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