Controlled electrodeposition of gold nanoparticles onto copper-supported few-layer graphene in non-aqueous conditions

Abstract

Graphene-Au hybrid materials show promise for applications ranging from biosensing to field emission devices. Electrodeposition is an inexpensive, fast and technically simple method for controlled deposition of nanoparticles but its use with graphene prepared by chemical vapor deposition (CVD) presents some problems. Cu foil is commonly used to catalyze the CVD process and the resulting graphene is most conveniently handled while retained on the Cu support. However Cu is able to spontaneously reduce Au salts in aqueous solution and hence deposition of nanoparticles via galvanic displacement occurs simultaneously with electrodeposition, and control of the growth process is lost. We show here that Au nanoparticles can be controllably electrodeposited onto Cu-supported few layer graphene (FLG) from N,N-dimethylformamide (DMF) solutions of a [AuCl4]− salt because spontaneous deposition of Au nanoparticles does not occur in this medium. Deposition occurs by the instantaneous nucleation mechanism when driven by an applied potential enabling the Au nanoparticle density to be controlled by the deposition conditions, predominantly the deposition potential. Following nucleation, nanoparticle growth is diffusion controlled. Our results demonstrate that the growth rate is similar in the presence and absence of an applied potential and control of growth time is key to controlling nanoparticle size.