▎ 摘　　要

Electric field dependent size-controlled gold nanoparticles (NPs), with a mean size ranging from 8 nm to more than 60 nm, are directly grown from bulk gold onto reduced graphene oxide (rGO) film in 0.2 M HCl aqueous solutions by electrochemical method. The Au NPs' distribution, from gradient with small area uniformity to the large area homogeneous all over the rGO film, is fully dependent on the electric field distribution between two electrodes. The particle size could be controlled by both the applied voltage and reaction time. By employing a uniform electric field, a high density Au NPs-graphene hybrid film with the particle size of tens of nanometres could be obtained for a surface enhanced Raman scattering (SERS) active substrate showing a high sensitivity of detecting rhodamine B molecules with the concentration as low as nM level, which may offer an effective way for size and distribution controlled fabrication of graphene based noble metal nanocomposites for potential utilization in detection and catalysis.