Abstract: Catalytic converters and insert materials for catalytic converters comprising metalized nanostructures coated on metal or ceramic honeycomb substrates are described. The nanostructures can be bonded directly to the channel walls of the metal or ceramic honeycomb substrates, and generally extend approximately 0.1 mm into the open pore volume of the substrates. The nanostructured coating can be used to support various catalyst formulations, where the nanostructured coating can provide advantages such as increasing reactivity of the catalysts by providing higher accessible surface area, decreasing light-off temperature through enabling smaller particle size of the catalysts, improving durability and lifetime of the catalysts through increased thermal stability, decreasing costs through reduced amounts of precious metals, and/or functioning as a filter for particulate matter.