成果報告書詳細
管理番号20090000000687
タイトル*平成20年度中間年報 水素製造・輸送・貯蔵システム等技術開発 次世代技術開発・フィージビリティスタディ等 革新的な次世代技術の探索・有効性検証に関する研究開発 非貴金属化合物を用いた水電解用高機能酸素発生アノード触媒の設計および開発
公開日2009/12/29
報告書年度2008 - 2008
委託先名国立大学法人横浜国立大学
プロジェクト番号P08003
部署名燃料電池・水素技術開発部 水素グループ
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 固体高分子型水電解ではアルカリ水電解と比較して、装置並びシステムのコンパクト化が期待されてきた。しかしながら、酸素発生反応(OER)を強酸性電解質において高電位下で行うために、反応性、耐久性、電気伝導性の観点から貴金属系触媒が現在使用されており、これがコスト低減を阻む要因となっている。我々は貴金属代替触媒として遷移金属化合物に着目した。そこで、今年度は具体的に遷移金属材料を用いて、1) 触媒作製並びに活性評価を行い、2) セルスケールの電解試験を行った。
英文要約Proton exchange membrane water electrolysis (PEMWE) have been expected for the compact equipment and system of water electrolysis compared with the alkali water electrolysis. Since oxygen evolution reaction (OER) of PEMWE on anode electrode occurred under the high potential in highly-acid electrolyte, precious metal oxide is used for the OER catalyst in the point of view of the reactivity, durability, electrical conductivity. However, the catalyst cost dominates highly on the total system and this becomes the barrier of the PEMWE system cost-cutting.
In order to solve these problems, we have focused the transition metal compound as the alternative catalyst of precious metal oxide. In this year, the possibility of transition metal compound of the PEMWE anode catalyst was investigated by the preparation and activity evaluation of catalysts, and the cell test of water electrolysis consisted of non-precious anode catalyst.
1. Preparation and activity evaluation of catalysts
Transition metal compounds were used ZrCN and oxidized ZrCN as new anode catalyst candidates. Oxidized ZrCN was prepared by heat treatment at 1000oC under the prescribed condition. Oxidized ZrCN powder was changed to the black color while initial ZrCN was brown. Oxidized ZrCN was measured by X-ray diffraction, and almost all diffraction peaks still identified that of ZrCN. These powders were supported on the Ti rod and then carried out electrochemical measurement. When the potential at 0.01 A/cm2 defined as oxygen evolution potential (EOER), EOER were 1.92 V (Ti rod), 1.86 V (ZrCN/Ti), 1.82 V (oxidized ZrCN/Ti) respectively. Therefore, oxidized ZrCN showed the highest catalyst activity.
2. Cell scale electrolysis test
The electrolysis cell consisted of oxidized ZrCN which has the highest OER activity as anode catalyst, Pt as cathode catalyst, and NafionR membrane as electrolyte. Anode catalyst loading was 0.64, 0.75, 0.91 mg/cm2, respectively, to optimize the cell performance. As a result, the electrolysis potential was decreased with increasing the catalyst loading. When the catalyst loading was larger than 0.75 mg/cm2, the electrolysis potential became 2.6 V at 1 A/cm2. The relationship between the water electrolysis efficiency and catalyst loading were also investigated. As a result, the efficiency was almost saturated at 0.75 mg/cm2 of catalyst loading, the highest electrolysis efficiency was 60%. Therefore, the catalyst loading of 0.91 mg/cm2 showed the best performance of cell test.
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