Separation of Nanoparticles in a Density Gradient: FeCo@C and Gold Nanocrystals

The right sort: A post‐synthesis, liquid‐phase separation method sorts nanoparticles by centrifugation in a medium with a density gradient. The particles are sorted according to particle size, clustering degree, and core density ρ (see picture; d=sedimentation distance). Solid–solid interactions between colloidal particles and stable phases are thus avoided. This versatile method allows for determination of the colloid size distribution in a suspension.