On the occasion of the Users Meeting, the M.Sc. Francesco Armillotta, XXXV cycle Ph.D. student in Physics at our University, has been awarded the “MAX IV Students Science Award 2021” of the Max IV Swedish synchrotron in Lund. This award is presented yearly to the student who has performed the best scientific contribution in a field related to an experiment involving the use of the Max IV synchrotron radiation.

The award has been attributed for the experimental observation of the hydroperoxyl molecule (O2H), a fundamental crossroad between two important pathways involved in the Oxygen Reduction Reaction (ORR), of strategic importance for renewable energies. Indeed, this mechanism is at the basis of the future generations of electrodes for metal-air rechargeable batteries, fuel cells, and in the production of hydrogen peroxide, the latter still having a particularly costly process for the global market. The study and the close focus on this reaction intermediate allow, on one side, to verify the hypotheses about the multiple reaction paths and, on the other side, to control and optimize the reaction.

In order to observe this molecule, characterized by a strongly elusive behavior, the M.Sc. Armillotta made use of a biomimetic model system, formed by a monolayer of planar molecules (cobalt porphyrins or CoTPyP) self-assembled on a supported single graphene sheet. After exposure to a mixed atmosphere of water and oxygen gases, under selected conditions, hydroperoxyl is formed and stabilized on the cobalt atom at the center of the porphyrin, thanks to a complex interplay between substrate, metal, and water. The study exploited sophisticated surface science techniques in order to investigate the reaction in situ, well beyond the usual limits of the ultra vacuum studies, by using near ambient pressure techniques, such as Non-linear Sum Frequency Generation (@Units) and X-ray Photoemission Spectroscopy (@MAX IV). For the comprehension of the phenomenology, the theoretical contribution of prof. Maria Peressi's group has been fundamental and, in particular, the work done by the M.Sc. D. Bidoggia, also a Ph.D. student in Physics at Units. All the work evolves in the framework of an international collaboration coordinated by prof. Erik Vesselli (Physics Dep. Units) and partially co-founded by a PRIN2017 Italian MUR project.