Nanoporous gold microelectrode prepared from potential modulated electrochemical alloying-dealloying in ionic liquid

Nanoporous gold (NPG) microelectrodes with high surface area and open pore network were success-fully prepared by applying modulated potential to a polycrystalline Au-disk microelectrode in ionic liquidelectrolyte containing ZnCl2at elevated temperature. During cathodic process, Zn is electrodeposited andinteracted with Au microdisk substrate to form a AuZn alloy phase. During subsequent anodic process,Zn is selectively dissolved from the alloy phase, leading to the formation of a NPG layer which can growwith repetitive potential modulation. Scanning-electron microscope and energy dispersive X-ray micro-scope measurements show that the NPG microelectrodes possessing nanoporous structures can be tunedvia potential modulation, and chemically contain a small amount of Zn whose presence has no obviousinfluence on electrochemical responses of the electrodes. Steady-state and cyclic voltammetric studiessuggest that the NPG microelectrodes have high surface area and keep diffusional properties of a micro-electrode. Electrochemical nitrite reduction and oxidation are studied as model reactions to demonstratepotential applications of the NPG microelectrodes in electrocatalysis and electroanalysis. These facts sug-gest that the potential-modulated electrochemical alloying/dealloying in ionic liquid electrolyte offers aconvenient green-chemistry method for the preparation of nanoporous microelectrodes.