Amine-Functionalized Mesoporous Silica @ Reduced Graphene Sandwichlike Structure Composites for CO₂ Adsorption

Amine-functionalized mesoporous silica @ reduced graphene (denoted as mSiO2@rGO-NH2) sandwichlike structure materials are synthesized via an oil–water stratification method and the self-assembled monolayers on mesoporous support (SAMMS) technique. The resulting mSiO2@rGO-NH2 materials exhibit excellent performance for physical and chemical synergetic adsorption of CO2 gas. Among them, with optimal contents of −NH2, the corresponding mSiO2@rGO-NH2-0.6 material is able to exhibit the high CO2 adsorption capacity of 3.64 mmol g–1 (0 °C, 1 bar), high CO2/N2 selectivity up to 47.6 (0 °C, 1 bar), moderate heat of adsorption, as well as good stability. Such improved adsorption performance is due to the reasonably design of sandwichlike structure containing multilevel pores (macro-/meso-/micropores), highly dispersed −NH2 groups, as well as the graphene sheets with good thermal conductivity, which enable the mSiO2@rGO-NH2-0.6 material to shorten the diffusion path of CO2, offer plenty of accessible amino sites, as well as transport adsorption heat effectively. Thus, the mSiO2@rGO-NH2 sandwichlike structure materials can selectively adsorb acid gas CO2 and have great application prospects in CO2 adsorption.