6533b82efe1ef96bd1293a91

RESEARCH PRODUCT

Local structure of nanosized tungstates revealed by evolutionary algorithm

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Nanostructured tungstates, such as CoWO4 and CuWO4, are very promising catalytic materials, particularly for photocatalytic oxidation of water. The high catalytic activity of tungstate nanoparticles partially is a result of their extremely small sizes, and, consequently, high surface-to-volume ratio. Therefore their properties depend strongly on the atomic structure, which differ significantly from that of the bulk material. X-ray absorption spectroscopy is a powerful technique to address the challenging problem of the local structure determination in nanomaterials. In order to fully exploit the structural information contained in X-ray absorption spectra, in this study we employ a novel evolutionary algorithm (EA) for the interpretation of the Co and Cu K-edges as well as the W L3-edge extended X-ray absorption fine structure (EXAFS) of nanosized CoWO4 and CuWO4. The combined EA-EXAFS approach and simultaneous analysis of the W L3 and Co(Cu) K-edge EXAFS spectra allowed us for the first time to obtain a 3D structure model of the tungstate nanoparticles and to explore in details the effect of size, temperature and transition metal type.