Electrodeposition of silver amalgam particles on ITO - Towards novel electrode material

Silver solid amalgam represents up to now the most suitable alternative electrode material to metallic mercury in electroanalytical chemistry. Controlled electrodeposition of variable (sub)micrometer-sized silver amalgam particles (AgAP) on the surface of transparent indium-tin oxide (ITO) electrode from an electrolyte containing Ag+ and Hg2+ ions is reported here, as a novel perspective method suitable for preparation of nano-structured silver amalgam electrode material. Elemental analysis of the composition and morphology of the AgAP decorating the ITO was studied by scanning electron microscopy including energy-disperse X-ray spectroscopy and by image processing software. Particle composition, size, and surface coverage are controllable by selection of the Ag+/Hg2+ ratio in the electrodeposition solution and by setting of individual parameters of applied double pulsed/potential chronoamperometry. Applicable potential window of thus prepared ITO-AgAP electrode was found to be within +0.2 to -1.0 V in 0.2 acetate buffer pH 5.0. Utilized voltammetric and chronoamperometric methods revealed significant enhancement in electrochemical reducibility of selected model organic nitro compound (shift of the peak potential about 300 mV to more positive potentials). Its further employment in UV/Vis spectroelectrochemical cell provided information about number of consumed electrons and kinetic characteristics. Furthermore preferential adsorption of calf thymus DNA at AgAP than ITO was observed by fluorescence microscopy indicating its potential applicability in (bio-)spectroelectrochemical methods. Further advantages and potential applications are also proposed and discussed.