Tin oxide as a promoter for copper@palladium nanoparticles on graphene sheets during ethanol electro-oxidation in NaOH solution

Abstract

In this work, tin oxide was examined as a promotor for the electrocatalytic activity of core-shell structured copper@palladium nanoparticles supported on graphene sheets [Cu@Pd/SnO2−Gr]. This transition metal oxide was added in different weight percentage values during the synthesis procedure. X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) were applied to characterize the formed electrocatalysts. The added SnO2 wt.% value in Cu@Pd/SnO2−Gr electrocatalysts affected their measured electrocatalytic performance during ethanol oxidation reaction in alkaline solution. The highest oxidation current density value was measured at the electrocatalysts containing 5 or 20 wt% SnO2. They also displayed increased electroactive surface area values when compared with those at other prepared electrocatalysts. Some kinetic information was derived from the scan rate and Tafel studies. Electrochemical impedance spectroscopy measurements revealed improved charge transfer characteristics with introducing increased tin oxide content in Cu@Pd/SnO2−Gr electrocatalysts. The enhanced activity and long-term stability of Cu@Pd/SnO2−Gr electrocatalysts recommend their application as anode materials in alkaline alcohol fuel cells.