Non-precious metal electrocatalyst for oxygen evolution in polymer electrolyte water electrolysis

摘要

The renewable energy like solar, wind and geothermal power etc. has been expected to be alternative energy resource for the sustainable society. To utilize the renewable energy effectively, the electrical and the hydrogen energy will be also important role as the secondary energy of renewable energy. For the collaborating the electricity and the hydrogen energy, interconversion technology system of them should be required. The conversion system from hydrogen to electricity is fuel cell system, and that from electricity to hydrogen is water electrolysis system.rnPolymer electrolyte water electrolysis (PEWE) has been studied for almost 40 years~(1-3) and, expected to be a compact and high efficient system of water electrolysis compared with the alkali water electrolysis.~(4-5) Since oxygen evolution reaction (OER) of PEWE on the anode electrode occurred at the high potential in strong acid electrolyte, precious metal oxide (e.g. IrO_2) is used for the OER catalyst from viewpoint of the reactivity, durability, and electrical conductivity.~6 However, the catalyst dominates most of the cost on the total system, and this is the barrier of cost reduction of the PEWE system. To obtain the alternative anode electrocatalyst with low cost, the non-precious metal oxides have to be investigated. From the point of view, we focused on the transition metal compounds were noticed. Especially the zirconium compounds, we had already found that they had high stability in acid solution and they also had the catalytic ability.~(7-8)rnIn this paper, in order to solve PEWE problems, we have focused on zironium compounds as the precious alternative electrocatalysts. Zirconium compounds of the PEWE anode catalyst has been investigated with half cells and water electrolysis cells.