Binary PdM catalysts (M = Ru, Sn, or Ir) over a reduced graphene oxide support for electro-oxidation of primary alcohols (methanol, ethanol, 1-propanol) under alkaline conditions

Abstract

High metal loaded (60 wt%) binary PdM (M = Ru, Sn, Ir) catalysts were synthesized on reduced graphene oxide (RGO) using the borohydride reduction method, and they were used for the electro-oxidation of simple alcohols, such as methanol, ethanol, and 1-propanol, in alkaline media. Cyclic voltammetry (CV) tests indicated that the Pd-based binary systems could improve electrochemical activities significantly compared to the monometallic Pd/RGO catalyst. Among the prepared catalysts, addition of Ru to Pd (PdRu/RGO) resulted in remarkably improved electrocatalytic activity in terms of larger peak current densities and lower onset potential in all electro-oxidation cases with methanol, ethanol, and 1-propanol. CO-stripping tests also revealed that the onset and peak potentials for the CO oxidation appear to decrease by the addition of Ru to Pd/RGO, indicating that the electro-oxidation of CO can take place more efficiently on the PdRu/RGO catalyst with the assistance of easily formed hydroxyl groups. Such an improvement of electrocatalytic performance can be ascribed to structural and chemical modifications of the Pd catalysts. Physicochemical properties of the PdM/RGO catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS).