Synthesis of carbon-encapsulated metal-based nanoparticles by gas/liquid interfacial plasma under high pressure

Carbon-encapsulated TiO2, Ag and Fe3O4 NPs are synthesized by pulse arc discharge plasma over glycine aqueous solution under high pressures, which is a novel plasma technique to fabricate metal-based NPs/C nanocomposites in one step. The carbon coatings are formed by utilizing glycine as a carbon precursor and confirmed to be amorphous carbon. While TiO2, Ag and Fe3O4 NPs are generated instantaneously via the erosion of the metal electrodes and reaction with the active oxidation radicals and molecular produced during the plasma generation over gas/liquid interface. It was found that the NPs are produced in the uniform size only under high operating pressure and the average size of the TiO2, Ag and Fe3O4 NPs were around 10.2 nm, 6.6 nm and 9.6 nm, respectively. The pulse arc discharge plasma was performed in different pressures, glycine concentrations and pulse times to investigate the effect of the influential factors on the formation of the carbon-encapsulated NPs in this plasma system. The carbon-encapsulated NPs are later annealed at 800 °C under Ar gas to construct the porous structure. In the MB degradation test, the porous carbon-encapsulated TiO2 NPs exhibit good adsorption capacity and improved photocatalytic activity.