Co/ZIF-8 Heterometallic Nanoparticles: Control of Nanocrystal Size and Properties by a Mixed-Metal Approach

A mixed-metal approach has been used to control the size and physicochemical properties of hetero-metallic Co/ZIF-8 nanomaterials. Intentional substitution of zinc with cobalt in a broad concentration range (from 0 to 100 molar percent with a 10% step) provided a series of Co/ZIF-8 nanoparticles, whose sizes could be tuned in the range from 20 to over 500 nm in diameter. Zinc ions from the ZIF-8 matrix were found to be uniformly substituted with the cobalt ions. The increase of nanoparticles size resulted in a change of their nitrogen sorption-desorption characteristics due to decreasing participation of the external surface area in the total surface area. Insights from UV-vis-NIR and IR spectroscopies, as well as remarks on nonlinear optical properties are also provided.