Studying Catalytically Viable Single-Crystalline Metal Oxide Nanorods Using Synchrotron-Based Scanning Hard X-ray Microscopy

Synchrotron-based scanning hard X-ray microscopy (SHXM) was used to extract localized chemical and structural information within a system of model alkaline earth-metal tungstate nanorods, characterized by multiple chemical configurations. Specifically, we have highlighted the practical ability of SHXM to probe chemically distinctive nanoscale species, consisting of (i) chemically doped versus (ii) solid solution-state nanorods of comparable dimension, synthesized using a template-directed method under ambient conditions. Indeed, we show that SHXM can be used to map out elemental distributions within individual anisotropic nanorods with nanoscale resolution, coupled with chemical sensitivity and specificity. Complementary electrochemical results suggest the possibility of using these nanorods as support materials for electro-oxidation reactions within an acidic electrolyte medium. Our structural and chemical composition results have been corroborated using parallel lines of inquiry involving scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. These measurements confirmed the relatively even and uniform distribution of the expected, individual elements within all of the nanorod samples tested.