Facile-green synthesis of nitrogen-doped carbon-supported ultrafine silver catalyst with enhanced electrocatalytic property

•Ultrafine Ag nanoparticles were grown on carbon surfaces with no toxic reagent.•The reduction temperature of silver nanoparticles was at room temperature.•The sample showed a superior oxygen reduction reaction activity.•A feasible synthesis mechanism has been proposed.

We have demonstrated a facile and green strategy to synthesize ultrafine silver nanoparticles monodispersed on N-doped three-dimensional carbon nanocloud surfaces without any toxic reagent. Folic acid was employed as the carbon precursor for forming N-doped carbon nanoflakes by a hydrothermal method. The as-prepared products can serve as both reducing agent and substrate, on which a high density of ultrafine Ag nanocrystals is stably grown in a homogeneously dispersive state spontaneously at room temperature. A feasible synthesis mechanism has been proposed by characterization of carbon precursor, nanomaterials composited without and with silver nanoparticles. It was found that the ethylenic and oxygenated groups led to the reduction process. The nanohybrids showed an enhanced electrocatalytic activity toward oxygen reduction reaction (ORR) in alkaline solution via a four-electron pathway. The catalyst also exhibited strong duration of methanol and good stability compared to commercial Pt/C catalysts.