Ensemble effects of nickel in surfactant-less prepared Pt-Ni materials on the carbon monoxide oxidative removal

This work reports the effect of the Ni content in a PtxNiy/C electrode on the CO oxidation reaction. A series of complementary and physicochemical techniques reveal the surface modification by the formation of Pt and Ni hydroxides which contribute to the removal of such model poisoning molecule in the utilization of organics as fuel in fuel cell applications. This cooperative activation of bimetallic materials, prepared without any organic surfactant, occurs at lower and lower potentials. As a result, a large 270 mV cathodic shift is observed when increasing the Ni amount up to 80% in the PtxNiy composition. XPS measurements are correlated with the electrochemical characterization of the PtxNiy/C electrodes surface through CO stripping investigations. Although there is a low shift of the Pt 4f7/2 peak, the presence of Ni-OH species in the close environment of Pt-COads mainly contributes to change the Langmuir-Hinshelwood mechanism into a bifunctional one which takes place at ca. 0.40 V vs. RHE. Graphical abstract