The fabrication of three-dimensional nanostructured foams from interconnected 2D materials such as graphene, h-BN, and transition metal dichalcogenides has shown to be a promising technique to explore their properties for several applications including energy storage, gas absorption, and catalysis applications [1-3]. Making bond-like interconnections between individual nanosheets can remarkably enhance their mechanical properties. Despite all advances, the controlled design of such interconnections remains a fundamental problem for many applications of h-BN foams. In this work, we report a technique to fabricate lightweight 3D macroscopic porous structures formed from h-BN nanosheets using a scalable in-situ freeze-drying synthesis. This method allows for the creation of intermolecular bonding between h-BN layers where PVA acts as a bridge to link the individual layers, thus forming a network-like structure at the nanoscale. Unlike pristine h-BN foams, which normally disintegrate immediately once removed from a freeze-drier, our h-BN/PVA foams show a robust freestanding structure with favorable mechanical stability. A detailed molecular dynamics (MD) study further verified and provided insights on the origins of such interconnections in improving the mechanical integrity. The foam also exhibits excellent CO2 absorption and storage under varying pressure values. The foam mechanism of CO2 absorption was also investigated through MD simulations.