Oxygen storage capacity of delafossite-type CuLnO2 (Ln = La, Y) and their stability under oxidative/reductive atomosphere

Delafossite-type CuLnO2 (Ln = La, Y) was synthesized and investigated their oxygen storage capacity (OSC) under oxidation/reduction cycle. CuLaO2 was synthesized by heating at 1000 °C for 6 h in N2 flow and CuYO2 was synthesized by heating of Cu2Y2O5 at 1190 °C for 1 h in N2 flow. The oxygen storage capacity values of CuLaO2 and CuYO2 at lower temperature were larger than that of CeO2-based materials which is used as a promoter of an automobile catalyst. The stability of delafossite-type CuLnO2 under cyclic oxidation/reduction atomosphere was investigated using XRD analysis. During the OSC measurement up to 700 °C, CuLaO2 decomposed to La2CuO4 and Cu2O. CuYO2 also partially decomposed to Y2O3, Cu2Y2O5 and Cu2O. These results suggest that oxidative decomposition of CuLnO2 occurred at high temperature. In lower temperature range, delafossite-type CuLaO2+x containing excess oxygen existed in both oxidative and reductive atmosphere and it partially decomposed during a hundred of oxidation/reduction cycles.

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