21^st World Nanotechnology Congress

If we imagine a factory of the future in which nanoparticle beams are integrated into the production of advanced materials or devices, then a set of critical research challenges emerge for Cluster Beam Deposition (CBD). These include control of nanoparticle composition, size, quantity (scale-up), interaction with the support, response to the environment and performance validation. Th e prize is a set of applications ranging from water treatment and theranostics to catalysis and memristors. The cluster beam approach is green; it involves no solvents and no effluents; particles can be size-selected and challenging combinations of metals (nanoalloys) can readily be produced. Here we discuss four of these research challenges: Environment (temperature), scale-up, formulation engineering and Validation :(1) Environment: aberration-corrected Scanning Transmission Electron Microscopy (STEM) is used to investigate the behavior of deposited clusters at elevated temperatures, including structural transformations and (core and surface) melting. (2) Scale-up: Industrial catalysis R&D typically requires a gram of catalyst or 10 mg of clusters at 1% loading on a suitable catalyst support. Th e Matrix Assembly Cluster Source (MACS) is based on ion beam sputtering of a rare gas matrix into which metal atoms are pre-loaded. A scaleup of five orders of magnitude in cluster intensity has been achieved to date. (3) Formulation Engineering: We will discuss

several means by which size-controlled clusters may be presented in a form matching the desired functional application, e.g., catalysis and theranostics. Th ese examples of formulation engineering on the nanoscale include direct deposition of metal cluster beams onto powders. (4) Validation: Finally will illustrate the validation challenge to show that cluster-based functional materials are superior to more traditional advanced materials. We will focus on the hydrogenation (both gas and liquid phases) of organic molecules over or applications in the fine chemicals sector and on water splitting.