Region-Selective Growth of Cu2O Shell on Gold Nanoprisms

Structural control in metal/semiconductor multicomponent nanoparticles can lead to advanced functional properties, as optoelectronic processes and accessibility (e.g., by charge carriers or molecules) of the different components can be simultaneously tailored. In this study, the impact of surface-adsorbed molecules (5-amino-2-mercaptobenzimidazole - AMBI) on the wet-chemical deposition of cuprous oxide (Cu₂O) shells on gold nanoprisms is investigated. It is shown that the otherwise excellent compatibility between gold and Cu₂O, and hence the shell deposition, is profoundly influenced by the presence of AMBI. The time evolution of the optical and structural properties during the shell growth indicates that the inherent Volmer-Weber characteristic of the Cu₂O deposition process gets greatly amplified by the surface adsorption of AMBI. Measurements performed on individual nanoparticles show that this originates in the inhomogeneous, multi-patch coverage of the particle surface. Under optimized synthetic conditions, the tips of the nanoprisms are effectively protected from Cu₂O overgrowth and are left bare.