III International Conference

PP-III-7a catalyst carrier allows to reduce platinum loading providing the same performance of thePEM-device.The second R&D goal is to develop the anode (oxygen evolution) catalysts for PEMelectrolysers.Since carbon materials have insufficient stability at the anode operatingconditions, the mixed metal oxides were applied as a catalysts carrier.The iridium is widely used as anode catalyst, but its activity and stability in acid solutionsis not the highest ones, alternative catalysts are required. Ruthenium has better activity thaniridium but it dissolves rather quickly at the electrolyser operating conditions. The usage ofhigh active Ru or Ir together with it stabilization by means of mixed oxide compositions isoffered. The main problem in this case is to find a proper synthesis technique. This techniquehas to be fast and cheap, and low platinum metal loading is strictly desirable. The simplesttechnique is to oxidize a corresponding metals alloy, but the high temperatures results in alow specific surface of the catalyst. The low temperature synthesis of solid oxide solutions ofsuch metals as Ta, Sn, Ti and some others seems to be very useful and some of them werestudied by our researches.Mixed oxide compositions based on IrO 2 , RuO 2 , SnO 2 , TiO 2 , Ta 2 O 5 have beensynthesized using the new low-temperature technique. The samples were examined by theX-ray diffraction. It was shown that binary and ternary mixed oxides form a solid rutilestructuredsolution where ruthenium and iridium oxides determine the crystalline structureand the particle size. Electrochemical behavior of mixed oxides was tested in electrolysis cellwith Nafion membrane. In particular, it was shown that ternary mixed oxide RuO 2 -IrO 2 -SnO 2shows rather high electrocatalytic activity (comparable with activity of IrO 2 ) and sufficientcorrosion stability. The similar results were received for mixed oxide anodes on the basis ofTa 2 O 5 . It was shown that such oxides, modified by IrO 2 and RuO 2 , have considerably smallerelectric resistance and higher stability.This work has been partially supported by the Council for Grants at the President of theRussian Federation (grant No MK-4218.2006.8) and INTAS (grant No 04-83-2585).482