Ag–Ni Janus nanoparticles by mechanochemical decomposition of Ag and Ni oxalates

Powder mixtures formed either by physical mixing or by co-precipitation of Ag and Ni oxalate crystals have been submitted to ball drop experiments at different temperatures in the presence of an aqueous solution containing polyvinylpyrrolidone. The mechanical loading induces a gradual decrease in the total mass of powders inside the reactor due to the occurrence of decomposition processes. Irrespective of temperature, physical mixtures decompose into Ag and NiO particles of about 5 nm, with evolution of carbon mono- and di-oxide. At temperatures lower than 350 K, the co-precipitated mixtures decompose into Ag–Ni solid solution nanoparticles, whereas at higher temperatures Ag–Ni Janus nanoparticles are also formed.