ORIGINAL PAPER Pt–Ni carbon-supported catalysts for methanol oxidation prepared by Ni electroless deposition and its galvanic replacement by Pt I. Mintsouli & J. Georgieva & E. Valova & S. Armyanov & A. Kakaroglou & A. Hubin & O. Steenhaut & J. Dille & A. Papaderakis & G. Kokkinidis & S. Sotiropoulos Received: 27 August 2012 / Accepted: 9 October 2012 / Published online: 23 October 2012 # Springer-Verlag Berlin Heidelberg 2012 Abstract Pt–Ni particles supported on Vulcan XC72R car- bon powder have been prepared by a combination of crys- talline Ni electroless deposition and its subsequent partial galvanic replacement by Pt upon treatment of the Ni/C precursor by a solution of chloroplatinate ions. The Pt-to- Ni atomic ratio of the prepared catalyst has been confirmed by EDS analysis to be ca. 1.5:1. No shift of Pt XPS peaks has been observed, indicating no significant modification of its electronic properties, whereas the small shift of the corresponding X-ray diffraction (XRD) peaks indicates the formation of a Pt-rich alloy. No Ni XRD peaks have been observed in the XRD pattern, suggesting the existence of very small pockets of Ni in the core of the particles. The surface electrochemistry of electrodes prepared from the catalyst material suggests the existence of a Pt shell. A moderate increase in intrinsic catalytic activity towards methanol oxidation in acid has been observed with respect to a commercial Pt catalyst, but significant mass specific activity has been recorded as a result of Pt preferential confinement to the outer layers of the catalyst nanoparticles. Keywords Platinum catalysts . Bimetallic catalysts . Methanol oxidation . Galvanic replacement Introduction Research into binary (or ternary) Pt-based metal catalysts for fuel cell reactions has been a long tradition, stemming from the need for improved catalytic activity and reduced cost that would permit widespread commercialization of fuel cells. Alloying or mixing Pt with either precious (such as Pd, Ru, Ir, Au, etc.) or early transition metals (such as Cu, Fe, Co, Ni, etc.) leads to a modification of its catalytic properties towards key fuel cell reactions (primarily oxygen reduction and hydrogen oxidation as well as methanol, for- mic acid, and borohydride oxidation) (see, for example, [1, 2]); depending on changes in the catalytic activity and catalyst structure, it may also lead to a decrease in precious metal loading. The advantages of direct methanol fuel cells (utilizing an inexpensive and easy-to-deliver liquid fuel that needs no pre-treatment and has a high theoretical energy density) have long been recognized (see, for example, [2, 3]) and the mechanism of methanol oxidation has been studied in detail so that effective catalyst optimization could be attempted. It is now accepted that the crucial steps of the I. Mintsouli : A. Papaderakis : G. Kokkinidis : S. Sotiropoulos (*) Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece e-mail: eczss@chem.auth.gr S. Sotiropoulos e-mail: eczss@otenet.gr J. Georgieva : E. Valova : S. Armyanov Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria A. Kakaroglou : A. Hubin : O. Steenhaut Department of Electrochemical and Surface Engineering, Vrije Universiteit Brussel, 1050, Brussels, Belgium J. Dille Service 4 MAT, Materials, Engineering, Characterization, Synthesis & Recycling, Ecole Polytechnique de Bruxelles, 1050, Brussels, Belgium J Solid State Electrochem (2013) 17:435–443 DOI 10.1007/s10008-012-1915-0