Template-based synthesis of metallic Pd nanotubes by electroless deposition and their use as catalysts in the 4-nitrophenol model reaction

The method of electroless plating offers a facile synthesis route to high-aspect ratio metal nanotubes. Despite the simplicity of the method, the traditional approach involves hazardous and toxic chemicals; to change this Green Chemistry has come into play. Since both, nanotechnology and Green Chemistry, have become important research topics, the combination of these offers new opportunities. According to the concept of Green Chemistry, Pd nanotubes were produced by using nonhazardous chemicals. The challenge was to rebuild the sensitisation and activation process of electroless plating and to find green reaction parameters for controlling the auto-catalysed heterogeneous nucleation of Pd. The produced Pd nanotubes were characterised by SEM and EDX. Furthermore TEM characterisation was done for determining the structural properties of Pd NTs. The efficiency of the reaction was quantified by ICP-OES and XPS measurements. To illustrate that green synthesized nanomaterials can be compared with conventionally prepared catalysts, the Pd nanotubes were tested in a model reaction to determine their catalytic activity. For this purpose the reduction of 4-nitrophenol to 4-aminophenol with NaBH4 was chosen, which also finds application in the synthesis of acetaminophen.