Electrodeposition of PdCu alloy and its application in methanol electro-oxidation

[Display omitted] ► We added triethanolamine (TEA) into the Pd2+ and Cu2+ mixed-ion electroplating bath to obtain a Pd-rich PdCu alloy. ► XRD analysis verified that PdCu alloys have smaller particle sizes compared with those deposited in TEA-free solutions. ► The cyclic voltammetry showed that alloys deposited with TEA have higher hydrogen desorption areas. ► Surface-modified PdCu alloys via redox replacement displayed the beneficial of Cu underpotential deposition. ► PdCu alloys fabricated with TEA and redox replacement showed better catalytic performance in the methanol electro-oxidation. This study demonstrates a simple electrodeposition method to fabricate the palladium–copper alloy on an ITO coated glass (PdCu/ITO) and its application in methanol electro-oxidation. Our approaches involve the co-reduction of Pd and Cu using triethanolamine (TEA) as a complexing agent in the electroplating bath and a Pd redox replacement of Cu on the surface of the as-prepared PdCu alloy. The phase structures, alloy compositions and morphologies of catalysts are determined by X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy, respectively. X-ray diffraction shows that the particle size of PdCu deposits shrink when the alloy is deposited in a TEA-contained solution. The electrocatalytic properties of PdCu alloys and Pd redox replacement modified PdCu alloys for methanol oxidation have been investigated by cyclic voltammetry. The PdCu alloy with atomic ratio of 20.5% Cu exhibits higher catalytic activity toward methanol oxidation compared with a pure Pd catalyst. PdCu alloys with smaller particle sizes associated with TEA agent and the surface confined Pd replacement are found to have enhanced catalytic performance in the electro-oxidation of methanol.