In this work, we report molecular layer deposition (MLD) of ultrathin poly(ethylene terephthalate) (PET) films on gram-scale batches of ultrafine particles for the first time. TiO₂ P25 nanoparticles (NPs) are coated up to 50 cycles in an atmospheric-pressure fluidized bed reactor at 150 °C using terephthaloyl chloride and ethylene glycol as precursors. Ex-situ diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis and transmission electron microscopy show the linear growth at 0.05 nm/cycle of uniform and conformal PET films, which are unattainable with conventional wet-phase approaches. The subnano and nano PET films not only suppress the photocatalytic activity of TiO₂ NPs by reducing the generation of hydroxyl radicals, but also improve the dispersibility of TiO₂ NPs in both organic and aqueous media. Still, the bulk optical properties, electronic structure and surface area of TiO₂ are essentially unaffected by the MLD process. This study demonstrates the industrial relevance of MLD to simultaneously tune the photoactivity and dispersibility of the commercial photocatalyst TiO₂ P25. Moreover, by rapidly modifying the surface properties of particles in a controlled manner at the subnanometer scale, particle MLD can serve many applications ranging from nanofluids to emulsions to polymer nanocomposites.

Microswimmers are small particles capable of converting available energy sources into propulsion owing to their compositional asymmetry and are promising for applications ranging from targeted delivery to enhanced mixing at the microscale. However, current fabrication techniques demonstrate limited scalability and/or rely on the excessive use of expensive precursor materials. Here, a scalable Pickering-wax emulsion technique is combined with galvanic electrochemistry, to grow platinum films from copper nanoparticles asymmetrically seeded onto SiO\textsubscript{2} microparticle supports. In this manner, large quantities of Pt-SiO\textsubscript{2} Janus microswimmers are obtained. Utilising copper as a templating material not only reduces synthesis time, material costs, and toxic waste, but also facilitates the further extension of this methodology to a range of functional materials. This electrochemical approach builds upon previous attempts to overcome the current limitations in microswimmer synthesis and offers exciting opportunities for their future development.