Effect of Ni addition on electrocatalytic activity of PdCu catalysts for ethanol electrooxidation: An experimental and theoretical study

A facile and clean electrochemical method has been developed for the synthesis of ternary PdCuNi catalysts on the surface of carbon Vulcan. The composition and morphology of the PdCuNi/C were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), X‒ray diffraction (XRD), EDX element mapping and transmission electron microscopy (TEM). The effect of Cu and Ni on the electrochemical activity of ternary PdCuNi alloy electrocatalysts was investigated for ethanol oxidation reaction (EOR). Between the different compositions, Pd35%Cu14%Ni2%/C catalyst exhibits superior mass activity which is about 10 times higher than that of commercial Pd/C catalyst. The onset peak potential for ethanol oxidation on Pd35%Cu14%Ni2%/C catalyst shifts to lower potential than that of PdCu/C and Pd/C catalysts. The stability tests revealed that the existing of Cu combined with Ni can improve the poison tolerance of Pd/C catalyst by removal of adsorbed CO-like intermediate species during ethanol oxidation. The experimental work is further investigated by theoretical study based on DFT-D calculations. The experimental and theoretical results exhibited similar trends in electrocatalytic activity of catalyst composition; indicating ternary PdCuNi alloys could be a promising anode catalyst for direct ethanol fuel cells.