Self-Assembly of Au/TiO₂ Sphere–Rod Mixtures into Binary Supraparticles

While the phase behavior of rod–sphere mixtures has been explored in 2D and 3D bulk systems, it has remained unexplored in smaller 3D assemblies. Especially, when combining plasmonic and semiconductor nanoparticles, assemblies with defined particle arrangements offer unique optical and (photo)catalytic properties.

In this work, we achieved the assembly of binary 3D assemblies tunable in size and phase behavior. Specifically, we assembled semiconductor TiO₂ nanorods and plasmonic Au nanospheres under spherical confinement and explored their phase behavior in experiments and simulations. Through evaporation-driven assembly of emulsion droplets, binary supraparticles were prepared with a phase tunable from colloidal membranes, consisting of single rod layers, to binary smectic phases, composed of alternating rod–sphere smectic layers.