Spontaneous silver deposition on cathodically pre-treated screen-printed carbon electrodes

Three different types of carbon screen-printed electrodes consisting of mesoporous carbon (MC), carbon nanofibers (CNF), and single-walled carbon nanotubes (SWCNT) were used as carbon supports for deposition of Ag, in the absence of reductant in the plating solution. The SPEs were characterized by Raman spectroscopy and show marked differences in their structure. To drive the metal deposition, the carbon supports were potentiostatically pre-treated in supporting electrolyte. The metal deposition occurred in AgNO3 solution and resulted in the formation of homogeneously distributed metal nanoparticles with type and amount depending on both the potential used in the pre-treatment step and the structure of the carbon electrodes. Larger metal amounts and higher particle densities (in the 10(9) cm(-2) range) together with smaller particle mean sizes (in the 40- to 60-nm range) were obtained by using more negative potential for the pre-treatment. A further way to influence the characteristics of the metal deposit was based on double or triple consecutive pre-treatment/deposition cycles. The obtained results are discussed in view of the possible sources of electron supply, necessary for the formation of the metal particles on the carbon carrying substrates.