Formation and Applications of Hierarchically Porous Carbon, Metals and Metal Oxides Formed by Nanocasting

Abstract

Hierarchically porous materials are of interest in a wide range of applications. If the materials are electronic or ionic conductors such materials are of interest as electrodes for use in fuel cells, flow batteries, electrocatalysis, and pseudo/supercapacitors. We have demonstrated the synthesis of hierarchically porous carbon, metal and metal oxide monoliths. Hierarchically porous silica with porosity at three length scales: 0.5-30 micrometer, 200-500 nm, and 3-8 nm, is used as a template to form these materials. The porosity of the silica template is produced by spinodal decomposition (0.5-30 micrometer), particle agglomeration (200-500 nm) and addition of surfactant or block copolymer (3-8 nm). Nanocasting: replication of all or part of the structure via one of a number of chemical replication techniques has been used to produce the carbon, metal oxide and metal replicas. The final surface areas of the materials can be as high as 1200 m2/g for carbon replicas, and >300 m2/g for metals and metal oxides. The use of the nanocasting technique allows for formation of materials that are compositionally or spatially heterogeneous.We report here results on the synthesis and characterization of hierarchically porous monoliths of carbon and, nickel and the use of some of these monoliths in catalysis and electrochemical capacitors.

Mesoporous materials and electrochemistry

“…In principle, the nanocasting approach could also be applied to electrogenerate non-siliceous metal hydroxides or oxides within hard mesoporous templates (since porous metal oxide monoliths prepared by nanocasting have been described 343 ), but this was not so common for getting mesoporous thin films.…”