Nanostructured surfaces that mimic Nature with novel functionalities: new research published in Nature Communications with the contribution of 3 students from the School
The work was coordinated by prof. Erik Vesselli from the Physics Department of the University of Trieste and involved an extended international collaboration framework in which Master Students in Physics (Alberto Ferrari and Matteo Rinaldi) and PhD students in Nanotechnology (Manuel Corva, Roberto Costantini, and Zgijing Feng) of the University of Trieste took part, together with prof. Giorgio Pastore and Giovanni Comelli. In addition, the collaboration included dr. Martina Dell’Angela (CNR-IOM), dr. Nicola Seriani (UNESCO ICTP) and people from the Institute of Materials Chemistry of the Vienna Technical University (dr. Matteo Roiaz, former student of the University of Trieste, dr. Chsristoph Rameshan, and prof. Gunther Rupprechter). The project was based on a recent research theme proposed by the group of prof. Vesselli after the design and commissioning of an innovative experimental setup that allows performing nonlinear laser spectroscopy. The objective is the investigation of the properties of nanostructured surfaces in situ and operando, thus observing the molecules on the surfaces “while they are working”. This is the reason why the recent findings of the group have already lead to high impact scientific publications (ACS Nano, JACS). In this particular case, the researchers of the collaboration adopted the so-called biomimetic approach in order to mimic Nature to synthetize new functional materials as catalysts, photovoltaic cells, or electronic/spintronic memories. The group assembled a bidimensional crystal of metalorganic molecules on a single graphene sheet. The used molecules (iron phthalocyanines) have a core structure that resembles that of the active part of hemoglobin (containing a Fe atom). After assembling the system under controlled vacuum conditions, the researchers pushed the pressure up to the working gas partial pressure of biologic systems (tens of mbar at room temperature) inducing carbonylation of the system. Then, it was observed that the green visible light of a powerful laser can be exploited to write information (bits) on each of the (CO)FeN4 centers of the matrix (the cells of the matrix are only 15 Å wide). The information can be read by means of an infrared-based probe thanks to the vibrational perturbations induced on the system by the local electronic excitation (the presence of the bit, consisting in a localized exciton). The researchers have also shown that for each adsorbed photon two bits (excitons) can be obtained, thus doubling the efficiency with respect to conventional solar cells. The group therefore proposes a biomimetic “bottom-up” approach for the synthesis of novel functional bidimensional materials and combines it with the novel available investigation setup. This research topic is of extreme interest in the view of the potential applicative purposes of the investigated materials in the fields of electronics, spintronics, and energy. The present work of the group based in Trieste focusses indeed on nanosystems for the synthesis of energy vectors and the conversion of greenhouse pollutants like for example carbon dioxide or other gases like carbon and nitrogen monoxide.
Editorial information: “Vibrational fingerprint of localized excitons in a 2D metalorganic crystal” Nature Communications 9 (2018) 4703, DOI: 10.1038/s41467-018-07190-1.