From electronic structure to the material that solves a problem

This line starts from a practical question: what makes an electrode work well, and why. The answer rarely lies in the overall composition of the material. It lies in the electronic structure of its surface, in where the band edges sit, and in what happens to that structure when a dopant is introduced or a metal cluster is deposited on top.

The group tackles that question with first principles calculations. Systems such as TiO₂ codoped with Pt and C, or with Pt and N, show synergistic effects that neither dopant produces on its own. In other cases the focus is on producing hydrogen and oxygen by water splitting, assessing which dopant combinations increase the specific surface area without degrading the redox capacity of the oxide.

The advantage of the computational approach is that it can explore a far wider range of compositions than experiment, and reach the lab with hypotheses already filtered. The price is that the model has to be reliable, and much of the group’s methodological effort goes precisely there: understanding how sensitive the results are to the choice of functional, of the Hubbard U parameter, or of the method used to extract the optical gap from an absorption spectrum.

At the nanoscale a material stops behaving like its bulk version. A cluster of thirteen platinum atoms on a titania surface is not platinum: its activity depends on the shape it adopts, on whether the surface is stoichiometric or reduced, and on the kind of vacancy anchoring it. This line studies exactly those dependencies.

The work covers several families of systems. Silver nanoclusters on titania, studied as possible remediators of nitrogen oxides, where the aim is to predict the band edge positions and their relation to the NO and NO₂ interaction. Supported platinum clusters, analyzed for their dynamic stability, their vibrational properties and their CO chemisorption. Bismuth oxyhalides such as BiOBr, where oxygen and halide vacancies define the optoelectronic properties and, with them, the photocatalytic performance.

What sets this line apart is that it does not stop at calculation. Theoretical results are checked against experimental surface characterization, and several of the studies explicitly combine theory and experiment: synthesis, X-ray diffraction, Raman spectroscopy and conductivity measurements brought into dialogue with simulation. That combination is what makes it possible to move from describing a system to explaining why it behaves the way it does.