Synthesis of bi-modal nanoporous Cu, CuO and Cu2O monoliths with tailored porosity

Nanoporous structures are exceptionally useful in catalytic, sensing and mechanical applications. However, precise control over the structure and composition of the nanoporous material is critical for the material to behave as desired. We report here a new bottom-up synthesis technique termed filter-casting for the creation of large scale (>1 cm) nanoporous structures which provide this precise control. Cu, CuO and Cu2O and bi-modal macro/nanoporous Cu structures were created with this technique to demonstrate the range of materials and structures which can be formed into nanoporous monoliths. Homogeneous nanoporous monoliths are synthesized using nanoparticles, and bi-modal or higher-order porosities are achieved using a sacrificial polystyrene template. The higher-order pore size is determined by the polystyrene particle diameter, and the nanopore size is set by the diameter of the nanoparticles. Surface areas as high as 34 m2 g−1, and relative densities between 12 and 58%, have been achieved. Filter-casting is a powerful new method for directly synthesizing large nanoporous monoliths with predetermined composition, pore size and pore structure.