Ammonium Bicarbonate Reduction Route to Uniform Gold Nanoparticles and Their Applications in Catalysis and Surface-Enhanced Raman Scattering

A new protocol for the synthesis of nearly monodisperse gold nanoparticles with controllable size is described. The pathway is based on the reduction of AuCl₄^– by ammonium bicarbonate in the presence of sodium stearate under hydrothermal conditions. The particle sizes could be easily tuned by regulating the reaction conditions including precursor concentration, reaction temperature and growth time. A tentative explanation for the reduction and growth mechanism of uniform gold nanoparticles has been proposed. The as-prepared gold particles showed good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH₄, and a surface-enhanced Raman scattering (SERS) study suggested that the gold nanoparticles exhibited a high SERS effect on the probe molecule Rhodamine 6G.