Precisely manipulation of core composition of core-shell-type cobalt polyoxoniobates and proton conduction study

The development of core-shell nanoclusters with controllable composition is of utmost importance as the material properties depend on their constituent elements. However, precisely tuning their compositions at the atomic scale is not easily achieved because of the difficulty of using limited macroscopic synthetic methods for atomic-level modulation. In this work, we report an interesting example of precisely regulating the core composition of an inorganic core-shell-type cobalt polyoxoniobate [Co26Nb36O140]32− by controlling reaction conditions, in which the inner Co-core composition could be tune while retaining the outer Nb-shell composition of resulting product, leading to a series of isostructural species with a general formula of {Co26-nNb36+nO140} (n = 0–2). These rare species not only can display good powder and single-crystal proton conductivities, but also might provide helpful and atomic-level insights into the syntheses, structures and composition modifications of inorganic amorphous core-shell heterometal oxide nanoparticles.