Pt(Ni) electrocatalysts for methanol oxidation prepared by galvanic replacement on TiO2 and TiO2–C powder supports

• Pt(Ni)/TiO2 and Pt(Ni)/TiO2–C catalysts were prepared by an electroless deposition-galvanic replacement method.
• XPS and ASAXS analyses of the catalysts showed no measurable alloying between Pt and Ni.
• Both catalysts have superior intrinsic catalytic activity for CO and methanol oxidation than Pt/C.
• The improved performance of the catalysts is due to Pt and TiO2 synergism.

Pt(Ni) catalysts were prepared by electroless deposition of Ni on TiO2 and mixed TiO2–C powder supports, followed by partial galvanic replacement of Ni by Pt in a chloroplatinate solution. Pt(Ni)/TiO2 and Pt(Ni)/TiO2–C catalysts were characterized by transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and anomalous small-angle X-ray scattering (ASAXS). XPS and ASAXS results showed no detectable alloying between Pt and Ni. In accordance with ASAXS analysis, the size of the Pt particles of the two samples is practically similar (2.1 and 1.5 nm). The electrocatalytic activity of the catalysts towards methanol oxidation and poisonous CO removal was assessed by cyclic voltammetry and chronoamperometry experiments and compared to commercial Pt/C catalysts. Despite the fact that the specific mass activity of the prepared catalysts is lower than that of the commercial material (as a result of their smaller surface area), both Pt(Ni)/TiO2 and Pt(Ni)/TiO2–C electrodes showed superior intrinsic catalytic activity (per Pt electroactive area) than the Pt/C catalyst. This is attributed to a synergistic effect of TiO2 on facile CO poison removal from Pt sites.