Characterization of Ru-Ir-O electrocatalyst powders for anode reaction in SPE
L. Morales S., G. Alonso, G. Orozco, A. Fernandez and L.G. Arriaga
Solid Polymer Water electrolyzer has shown to be a promising method of producing clean hydrogen (1, 2). Recently IrO2 material has been examined as the anode or oxygen evolution electrode(3). In particular, a chemical method is used to producing Ru, Ir sulfide powders. IrO2 and RuO2 noble metal oxides as electrocatalyst are well established in many industrial electrochemical processes, most of them are prepared by thermal decomposition of metal precursors onto titanium substrates (2). This method is unsuitable for SPE electrolyzers due to the difficult in obtaining good contacts between the electrocatlytic layer and the membrane electrolyte. Therefore, to obtain an electrocatalytic layer on the membrane, either pre-prepared powders may be applied as an ink to the membrane. Recently an ink-spray method is used, so have been concentrating on preparing Ru-Ir-O powders (3). In this work is investigated the synthesis, structural characterization and electrochemical measurements of Ru-Ir-O powders. The chemical synthesis was by (NH4)2IrCl6 and (NH4)2RuCl6 salts, after a constan stirring, the mixture was introduced to termical treatment at 400°C in air and H2S/H2 atmosphere. The powders were characterized by BET, XRD, SEM and TEM. Electrochemical measurements was carried out in acid medium 0.5M H2SO4 at 25°C in N2 atmosphere, the experiments were realized in electrochemical three electrodes convectional cell, a carbon plate as counter electrode and hydrogen electrode as reference. The cyclic voltammetry was realized at 20mV/s in a potential interval of 0 to 2.0 V vs RHE, The rotaing disk electrode measurements was realized at 20mV/s at 200rpm, 400rpm, 900rpm, 1600rpm and 2500 rpm.
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