Metallic and bimetallic Cu/Pt species supported on carbon surfaces by means of substituted phenyl groups

Carbon surfaces were functionalized with metallic species by means of 4-sulfophenyl groups previously grafted on the electrode surface by electrochemical reduction of the corresponding diazonium cations “in situ” generated from the corresponding amine. The functionalization with metallic copper is based on electrostatic interactions between sulfonate groups present on the modified carbon surface and copper(II) cations in aqueous solution and its subsequent chemical or electrochemical reduction to metallic copper. Bimetallic modified electrodes based on Cu/Pt were also obtained by replacement of metallic copper on the carbon surface by immersion of the surface in a K2PtCl6 aqueous solution. The amount of copper was estimated by stripping voltammetry in aqueous 0.5 M H2SO4 whereas adsorption/desorption of hydrogen was used in the same electrolyte to quantify the platinum present on the carbon surface. The resulting metallic functionalized surfaces were characterized by cyclic voltammetry to determine their activity for the electrochemical reduction of nitrate and the hydrogen evolution reaction (HER).