Type III porous liquids (T3PLs), which combine the benefits of solids and liquids, have gained attention for CO2 emission reduction and sustainable development. A key challenge is maintaining porosity by using small-pore-sized pore generators while avoiding the loss of porosity during dispersion in solvents. Traditional methods require complex postsynthetic modifications, which can compromise structural integrity and stability. In this study, MOF-5 with varying particle sizes was used as a carbon precursor to examine the impact of the particle size on metal–organic framework (MOF)-derived carbons. MCMOF-5, with an internal cubic cavity and a surface-dense graphene layer, was dispersed in poly(dimethylsiloxane) (PDMS) to prepare the T3PLs. MCM-410-3%, formed by MCMOF-5 and PDMS410, exhibited excellent CO2 sorption (1.89 mmol/g at 10.0 bar, 298 K) and cyclic stability, benefiting from well-developed carbon pores and protective graphite layers. Additionally, it maintains a low viscosity (108 mPa·s) and low density (0.551 g/cm3). This simple strategy of enhancing porous solid interfaces through calcination offers a new approach to the preparation of T3PLs and provides a new option for the use of CO2 capture materials.