1) Atomic Quantum Clusters (AQCs)

When the size of a metal nanoparticle (NP) is reduced to below ≈ 2 nm (i.e. less than ≈150 atoms) the quantum confinement of the free electrons causes the discretization of energy levels and, consequently, the lost of the metallic (or plamonic) properties, evolving to a non-metallic or excitonic state.

For the smallest AQCs, sizes below ≈ 1 nm (≈ 30 atoms), the dimensions are comparable to the Fermi wavelength, and the quantum confinement is so severe, that a difference of only one simple atom entails a completely different behavior.

The figure below shows a 3D Periodic Table of the elements to highlight the idea that, between the atomic behaviour and the bulk-like behaviour of NPs, a whole range of novel materials, with their own different size-dependent properties (i.e. different well-defined geometrical and electronic structures) appear at the Angstroms scale. Our current research interests in this novel and disruptive Angstroms technology of AQCs are:

1) Synthesis of naked AQCs.

There is still a great barrier to overcome before one can explore the enormous potential of naked AQCs, which is due to the lack of easy and scalable methods of synthesis. In this regard, we developed in the last years different strategies, based on kinetic control (see figure below), mainly using microemulsions and electrochemical techniques. Using a fine control of the experimental parameters one can focus the formation of highly monodisperse AQC samples. As an example we recently reported the synthesis of almost 100% Cu₅ AQCs in Huseyinova et al., J. Phys. Chem. C 2016.

2) Catalytic Properties of AQCs.

In the field of catalysis, many encouraging results for different reactions have been put forward in the last decade, demonstrating that AQCs with the appropriate size and composition can open a new area in molecular/material science for the direct design of catalysts with improved efficiency and selectivity. As an example, we reported –together with the group of Prof. Avelino Corma (Univ. Valencia)- the exceptional catalytic properties of Au AQCs for the oxidation of thiols:

3) Photocatalytic properties of AQCs

Because of their excitonic behaviour, AQCs can be considered as Quantum Dots (QDots).  Moreover, due to their high stability and Angstroms-size, AQCs-QDots favour the separation of photogenerated charges, displaying much more photonic efficiencies than other common semiconductors and QDots. As examples, we can mention:

4) Electrocatalytic properties of AQCs.

Exceptional electrocatalytic properties of AQCs have been putted forward in the last decade. As a particularly interesting example we used such properties for reducing alcohol toxicity in living cells with Ag AQCs:

5) Biomedical properties of AQCs.

One almost unexplored field of interest is the biomedical potentialities of AQCs. We have shown, for example, that AQCs can inhibit the action of toposimerases.