The past decades have seen a rapid growth of research on the potential applications of nanoparticles, and their assembly as "artificial atoms" into increasingly complex structures and composite materials. Motivated by favourable properties, such as the high density of active unsaturated atoms residing on their surface, and discontinuous effects arising from their confined electronic band structure, nanoparticles and nanoparticle composites are of specific interest to fields ranging from catalysis to nanophotonics. One of the more promising aspects of using nanostructured materials is the ability to combine mixtures of different nanoparticles to improve the performances of the starting materials or even observe emergent properties. This feature has been regularly exploited in heterogeneous photocatalysis, where the relatively poor visible light absorption and quantum efficiency of base photocatalysts such as TiO 2 can be improved by incorporating cocatalyst metal nanoparticles. Typically, materials are functionalised with nanoparticles by either synthesising the nanoparticles directly onto the support, or by heteroaggregating pre-synthesised metal nanoparticles. In this second approach, the size and the geometry of the nanoparticles can be pre-defined, in turn providing greater control over their functionality However, there are significant hurdles still facing the application of nanoparticles to many real-world situations. One of the key issues is that their small size not only makes them hard to process, but also poses health and safety concerns. Furthermore, the recovery of nanosized objects from liquids is difficult, which introduces additional problems when applications require that the nanoparticles are suspended in a fluid. Nanoparticles are also more prone to aggregation due to their high surface energy, and more challenging to disperse in liquids than their larger counterparts. To overcome these and other challenges, nanoparticles are often supported on a secondary material. Among the various strategies for nanoparticle support, attaching them onto microparticles has received comparatively less attention. Nevertheless, microparticles possess signifi-cant favourable attributes as a support material. First and foremost, they enable dispersion in liquid media while retaining the high mass-transfer rates and high surface areas of the nanoparticles, with the advantage of their easy removal from suspension. For example, Marques et al. demonstrated that the advantages of slurry-type photocatalytic reactors could be retained without the need for a time-consuming and complex nanofiltration step to recover the catalyst upon attaching it onto microparticles. Moreover, the size, morphology, porosity, and composition of microparticles can also be adjusted drawing upon the extensive and well-established literature of colloidal synthesis, allowing targeted development of the support material towards the desired application.