Organized by the Institute of Experimental Physics, University of Bialystok and the Institute of Atomic Energy, Swierk under the auspices of the European Crystallographic Association; Committee of Crystallography, the Polish Academy of Sciences; and the Polish Neutron Scattering Society The School is financially supported in part by the International Union of Crystallography; the European Crystallographic Association; the European Office of Aerospace Research & Development; the Ministry of Science and Information Society Technologies; the Warsaw University of Technology; and the University of Bialystok.
		Modification of catalytic activity of Cu-based amorphous alloys by cathodic hydrogen charging M. Pisarek1,2, M. Janik-Czachor2, A. Gebert3, Á. Molnár4, P. Kędzierzawski2, B. Rác4 1Faculty of Materials Sciences and Engineering, Warsaw University of Technology, Warsaw, Poland 2Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland 3 Leibniz-Institute for Solid State and Materials Research (IFW) Dresden, Germany 4Department of Organic Chemistry, University of Szeged, Szeged, Hungary Topics Degradation processes occurring at the surface and in the bulk of Cu-based amorphous alloys during cathodic hydrogen charging were used for a benefit of enhancing their catalytic activity. Thus, the degradation processes caused by hydrogen charging (modifying the structure, composition, and morphology of the substrate) proved to be useful methods of the transforming Cu-Hf and Cu-Ti amorphous alloys precursors into highly active and stable catalysts. Hydrogen charging of Cu65Hf35 and Cu61Hf39 amorphous alloy ribbons at i = -1 mA/cm2 in an alkaline solution (0.1 M NaOH) was used to study the effect of hydrogenation on the process of crystallization and morphology chenges. A similar procedure was applied in an acid solution (0.1 M H2SO4) to introduce more hydrogen to bring about more pronounced morphological and structural changes. The samples were then catalytically tested for dehydrogenation of 2-propanol. Catalytic activity increased up toa conversion level of 88% at selectivities to acetone of about 95%. The structural, chemical and morphological changes were followed by XRD, AFM, SEM, AES and X-ray electron probe microanalysis (WDS). The hydrogen content was determined by elemental analysis, or by gas extraction. The same method of activation was also used for Cu60-Ti40 amorphous ribbons. The changes within the ribbon and at the surface and their interrelation to the catalytic activity were followed by the methods mentioned above, while the amount of Cu segregated at the surface was estimated by "anodic stripping". The conversion of a test reaction was enhanced up to 66%, it was thus much higher than those obtained after all the other pre-treatments applied previously. A tentative model of catalytic reaction over activated Cu-Hf or Cu-Ti is discussed. Surface characterizations were performed using a Microlab 350 located at the Physical Chemistry of Materials Centre of the Institute of Physical Chemistry, PAS and of the Faculty of Materials Science and Engineering, WUT. This work was financially supported by the Institute of Physical Chemistry, PAS and by the Foundation for Polish Science through a generous fellowship for M.Pisarek.