[2P01-29] Poster session

[2P12] Element–selective soft X–ray PEEM investigation of Cu segregation and valence states in Cu–Doped CoGa intermetallic catalysts

*Kouyou Fujimoto^1,2,3, Yushi Sumida^1,2,3, Sena Matsushita⁴, Takayuki Kojima⁴, Takuo Ohkochi^2,3 (1. Graduate School of Engineering, University of Hyogo (Japan), 2. Laboratory of Advanced Science and Technology for Industry, University of Hyogo (Japan), 3. RIKEN SPring-8 Center (Japan), 4. Faculty of Textile Science and Technology, Shinshu University (Japan))

We investigated how Cu addition modifies the surface electronic structure of CoGa intermetallic catalysts, which show enhanced selectivity in the alkyne–selective hydrogenation of C₃H₄ when doped with ~5% Cu. Using element–resolved soft X–ray PEEM and XAS at SPring–8 BL17SU, we visualized Cu distribution and probed its valence states. PEEM elemental maps revealed that Cu segregated over the surface, but its distribution was heterogeneous, forming Cu–rich and CoGa–rich regions. Cu L_2,3–edge XAS showed metallic behavior at low Cu concentration, whereas the 5% Cu sample exhibited weakly oxidized features. Notably, the Cu valence state displayed no prominent spatial variation, indicating that segregated Cu forms a surface layer with nearly uniform oxidation after air exposure. These findings suggest that homogeneous surface Cu states may contribute to the improved catalytic selectivity.

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