Synthesis of epsilon-Keggin-Type Cobaltomolybdate-Based 3D Framework Material and Characterization Using Atomic-Scale HAADF-STEM and XANES

Igarashi T; Zhang ZX; Haioka T; Iseki N; Hiyoshi N; Sakaguchi N; Kato C; Nishihara S; Inoue K; Yamamoto A; Yoshida H; Tsunoji N; Ueda W; Sano T; Sadakane M

Inorganic Chemistry, Vol.56, No.4, 2042-2049, 2017

DOI10.1021/acs.inorgchem.6b02748 Export Citation

Synthesis of epsilon-Keggin-Type Cobaltomolybdate-Based 3D Framework Material and Characterization Using Atomic-Scale HAADF-STEM and XANES

Igarashi T, Zhang ZX, Haioka T, Iseki N, Hiyoshi N, Sakaguchi N, Kato C, Nishihara S, Inoue K, Yamamoto A, Yoshida H, Tsunoji N, Ueda W, Sano T, Sadakane M

We describe the preparation of epsilon-Keggin-type cobaltomolybdate-based 3D frameworks with sodium cations, NaH9[epsilon-(CoMoV8MoVI4O40Co2II)-Mo-II], and their characterization by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) spectroscopy. Atomic-scale HAADF-STEM images of epsilon-Keggin compounds were obtained for the first time, and positions of Mo and Co were confirmed. Furthermore, clear evidence of the presence of a CoO4 tetrahedron was obtained by X-ray absorption near-edge structure (XANES) analysis. Their characterization clearly revealed that epsilon-Keggin-type cobaltomolybdate units, [epsilon-CoMo12O40](n-), constructed by a central CoIIO4 tetrahedron and 12 surrounding MoO6 octahedra, are linked with Co-II to form 3D frameworks.