Effect of sodium oxalate on the intensity of surface resonance plasmon of the copper nanoparticles used as substrates for the synthesis of ultrasmall Cu-Pt nanoparticles and the study of their catalytic activity on the oxygen reduction in acid electrolyte

Abstract The influence of hexadecyltrimethylammonium bromide (CTAB) and sodium oxalate (SO) on the formation of copper (Cu) nanoparticles is studied through the surface plasmon peak (λmax) measured by Uv-Vis spectroscopy. In addition, the electrocatalytic activity and stability for the oxygen reduction reaction (ORR) in acid electrolyte of these Cu nanoparticles alloyed with platinum (Cu-Pt) are investigated by cyclic voltammetry (CV) and rotating disk electrode linear voltammetry (RDE-LV). A λmax around 570 nm, characteristic of metallic Cu spherical NPs, is observed only when the Cu+2 ions are reduced with sodium borohydride (BH) in the presence of CTAB; moreover, the λmax intensity increases significantly when sodium oxalate (SO) is added to this reaction mixture. The Cu+2:BH:CTAB:SO ratio was optimized as a function of the λmax intensity to know qualitatively the production yield of metallic Cu NPs. Transmission electron microscopy results show that Cu-Pt nanostructures supported on untreated Vulcan carbon (Cu-Pt/VC) grow as clusters of ultra-small bimetallic nanoparticles (