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

Leveraging molecular-level controls to enhance CO 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(BH ) nanocrystals and reduced graphene oxide (MBHg) is described. These nanomaterials exhibit kinetically controlled, irreversible CO uptake profiles with high uptake capacities (>19.9 mmol g ) at low partial pressures and temperatures between 40 and 100 °C. Systematic experiments and first-principles calculations reveal the mechanism of reaction between CO and MBHg and unveil the role of chemically activated, metastable (BH -HCOO) centers that display more thermodynamically favorable reaction and potentially faster reaction kinetics than the parent BH centers. Overall, it is demonstrated that size reduction to the nanoscale regime and the generation of reactive, metastable intermediates improve the CO uptake properties in metal borohydride nanomaterials.