HOR in Alkaline Membrane Fuel Cells: Hollow Octahedral Electrocatalysts

Abstract

We have recently explored the binary system of Ni x Pt 1-x alloys for HOR in alkaline membrane fuel cells and demonstrated our ability to generate mainly [111] facets in octahedral nanocrystals using colloidal synthesis. [1] In a further experiment, galvanic replacement reaction has been used to introduce a third metal and has been successful in the case of other PGM, while etching part of the Ni. In some cases, the etching process yields hollow octahedral frames (see figure). The catalysts are characterized by electrochemical measurements in 0.1 mol/L of KOH using cyclic voltammetry and polarization curves on glassy carbon rotating disc electrodes. After screening of the best electro-catalysts, a full characterization is carried out to probe the atomic structure by HRTEM, HAADF and EELS, in parallel with gas adsorption spectroscopy (mainly FTIR of CO species) and calorimetry to determine the nature of surface sites on the catalyst. [1] Shviro, M.; Zitoun, D. RSC Adv. 2013 , 3 , 1380;