Highly selective carbon capture by novel graphene-carbon nanotube hybrids

Abstract

Numerous nanomaterials with novel architectural segments are being currently designed to achieve high CO2 capture selectivity and adsorption. Here, we demonstrate molecular dynamics simulations of a range of newly modelled graphene-CNT hybrids in CO2/N2 and CO2/H2O mixtures. The hybrids possess novel pseudo-triangular voids formed by embedding a graphene sheet in between multiple CNTs along with the cylindrical CNT pores. The pseudo-triangular voids formed with considerably larger diameter CNTs at an industrially relevant CO2/N2 proportion reveals extremely high CO2 capture selectivity of 0.957 compared to 0.692 by original CNT pores, resulting in an overall enhanced hybrid interior selectivity of 0.762. Simulations of these systems with a rise in temperature from 200 to 600 K revealed significant desorption, however, for an initial rise from 200 to 400 K, the triangular voids offered higher resistance to desorption compared to the CNT pores. The hybrids constructed with small diameter CNTs always depicted the overall selectivity values close to 1, independent of CO2/N2 proportion.