Synthesis of carbon-encapsulated gold nanoparticles in polyimide matrix

Carbon-encapsulated Au nanoparticles were synthesized by heat-treating a monolayer of Au nanoparticles sandwiched between two polyimide thin films in an oxidizing environment. Thermal imidization of the polyamic acid/Au/polyamic acid film stack produced well-dispersed Au nanoparticles and subsequent annealing at 1000 °C in an oxidizing environment resulted in a monolayer of 33-nm-sized Au nanoparticles encapsulated by a carbon layer with uniform thickness of 2-2.5 nm. It was also demonstrated that carbonaceous material with vastly different morphologies could develop around the Au nanoparticles depending on the heat-treatment atmosphere during carbonization.