Controlling the Distribution of Supported Nanoparticles by Aqueous Synthesis

Synthesis of supported nanoparticles with controlled size and uniform distribution is a major challenge in nanoscience, in particular for applications in catalysis. Cryo-electron tomography revealed with nanometer resolution the 3D distribution of phases present during nanoparticle synthesis via impregnation, drying, and thermal treatment with transition metal salt precursors. By conventional methods a nonuniform salt distribution led to clustered metal oxide nanoparticles (NiO, Co 3 O 4 ). In contrast, freeze-drying restricted solution mobility during drying and a more uniform nanoparticle distribution was obtained. By this fundamental insight into catalyst preparation, controlled synthesis of supported catalysts was achieved in a way that is also applicable for other nanostructured materials.