Template-free and direct electrochemical deposition of hierarchical dendritic gold microstructures: Growth and their multiple applications

Hierarchical dendritic gold microstrutures (HDGMs) with secondary and tertiary branches are directly electrodeposited on an indium tin oxide (ITO) substrate without the use of any templates, surfactants, or stabilizers. The effects of electrodeposition potential and HAuCl₄ concentration on the formation of HDGMs and time-dependent morphological evolution are investigated in detail. A diffusion-limited aggregation (DLA) mechanism is used to explain the formation of HDGMs. Typically, the as-synthesized HDGMs exhibited much higher electrocatalytic activity and enhanced stability toward ethanol electrooxidation compared to bulk gold electrode and also display great Raman enhancement activity with the detection limit of 10^-12 M for rhodamine 6G. The surface of HDGMs possesses hydrophobicity even without modification with low-surface-energy coatings and has a remarkable superhydrophobic property even in corrosive solutions over a wide pH range after the treatment with n-dodecanethiol. In addition, (super)oleophobicity is successfully obtained by modification with 1H,1H,2H,2H-perfluorodecanethiol.