Owing to the geometrical features of 2D graphene intercalated into 3D mesoporous silica, CO2 sorption increased by 51% and the heat of sorption reduced by up to 27% as compared to a pure 3D mesoporous silica sorbent without graphene. The superior performance of the amine-functionalised 2D/3D hybrid sorbent was attributed to the enhanced porosity and graphene physisorption at the expense of amine chemisorption.