Finite-size effects of nanometric metallic particles can be exploited to obtain tailored and novel electronic and chemical properties. At variance with traditional metal-dispersed supported heterogeneous catalysts widely employed for today's applicative purposes, a thorough control of size, shape, and alloying, together with a careful choice of the templating support, may yield to a bottom-up approach to the design of novel materials. However, challenges show up when dealing with realistic systems. Indeed, proper recipes to grow well-ordered arrays of equally sized supported clusters are not straightforward, even if self-assembly and seeding strategies are adopted or if cluster sources are employed. In addition, with respect to model ultrahigh-vacuum conditions under which these systems are generally investigated, realistic working conditions require thermal stability, in order to avoid sintering effects, while interaction with an ambient pressure gas phase may influence the shape, composition, and chemical state of the nanoclusters yielding restructuring, poisoning, and deactivation. In this essay, we review up-to-date experimental and theoretical approaches to investigate these issues, providing examples of selected systems, and outline a perspective direction to progressively close the material and pressure gaps for the effective transferability of modern surface science modeling to potentially applicative conditions.
