Growth of electrodeposited platinum nanocrystals studied by atomic force microscopy

Platinum crystal growth by electrochemical deposition on highly orientated pyrolytic graphite (HOPG) surfaces was studied by atomic force microscopy (AFM) operated in the tapping mode. In the absence of a supporting electrolyte, 2D Pt nanoparticles aggregated. After reaching a critical mobile particle size, subsequent growth of platinum morphology appeared to be dominated by surface diffusion of mobile Pt particles. In the presence of HClO4, 3D growth of deposited platinum appeared to be the dominant mechanism. Various morphologies of Pt electrodeposition on HOPG are the consequence of competing 3D growth and 2D particle growth. Anions specifically adsorbed on platinum may also play an important role in affecting 2D versus 3D crystal growth.