Chiara Gattinoni

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Gattinoni

First Name

Chiara

ORCID

0000-0002-3376-6374

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Publications 1 - 10 of 14

Magnetoelectric effect in hydrogen harvesting: magnetic field as a trigger of catalytic reactions
Kim, Donghoon; Efe, Ipek; Torlakcik, Harun; et al. (2021)
arXiv
Magnetic fields have been regarded as an additional stimulus for electro- and photocatalytic reactions, but not as a direct trigger for catalytic processes. Multiferroic/magnetoelectric materials, whose electrical polarization and surface charges can be magnetically altered, are especially suitable for triggering and control of catalytic reactions solely with magnetic fields. Here, we demonstrate that magnetic fields can be employed as an independent input energy source for hydrogen harvesting by means of the magnetoelectric effect. Composite multiferroic CoFe2O4-BiFeO3 core-shell nanoparticles act as catalysts for the hydrogen evolution reaction (HER) that is triggered when an alternating magnetic field is applied to an aqueous dispersion of the magnetoelectric nanocatalysts. Based on density functional calculations, we propose that the hydrogen evolution is driven by changes in the ferroelectric polarization direction of BiFeO3 caused by the magnetoelectric coupling. We believe our findings will open new avenues towards magnetically induced renewable energy harvesting.
Adsorption of Surfactants on alpha-Fe2O3(0001): A Density Functional Theory Study
Gattinoni, Chiara; Ewen, James P.; Dini, Daniele (2018)
The Journal of Physical Chemistry C
From corrosion inhibition to lubrication, a detailed understanding of the interactions between surfactants and iron oxide surfaces is critical for a range of industrial applications. However, there is still limited understanding of this behavior at the atomic-level, which hinders the design of improved surfactant molecules. In this study, the adsorption of three surfactants which are commonly employed as lubricant additives (carboxylic acid, amide, monoglyceride) on a α-Fe2O3(0001) surface is studied with density functional theory. The nature and strength of the adsorption for the different surfactants, as well as their propensity to deprotonate on the surface, is studied at a range of surface coverages. In agreement with the available experiments, strong chemisorption on α-Fe2O3(0001) is observed for all cases considered. Dissociation is energetically favorable for carboxylic acid and glyceride surfactants through the formation of a surface hydroxyl group, whereas this is not the case for amides. Glycerides form the most strongly adsorbed films at both low and high surface coverage due to the presence of multiple functional groups, which can all act as binding sites. However, the large size of the glyceride headgroup also means that adsorption is stronger at low coverage, where the formation of multiple bonds with the surface is possible, than at high coverage. Conversely, carboxylic acid films have similar stability at low and high coverage, where van der Waals forces between proximal tailgroups stabilize the adsorption structures. The results of this study provide atomic-level insights which help to explain friction results from previous macroscopic tribology experiments and classical molecular dynamics simulations. They also facilitate the molecular design of new surfactants to maximize the adsorption energy, surface coverage, and ultimately friction reduction on iron oxide surfaces.
Prediction of a strong polarizing field in thin film paraelectrics
Gattinoni, Chiara; Spaldin, Nicola (2022)
Physical Review Research
We demonstrate the existence of a polarizing field in thin films of insulators with charged ionic layers. The polarizing field derives from the same physics as the well-known depolarizing field that suppresses ferroelectric polarization in thin-film ferroelectrics, but instead drives thin films of materials that are centrosymmetric and paraelectric in their bulk form into a noncentrosymmetric, polar state. We illustrate the behavior using density-functional computations for perovskite-structure potassium tantalate, KTaO3, which is of considerable interest for its high dielectric constant, proximity to a quantum critical point, and superconductivity. We then provide a simple recipe to identify whether a particular material and film orientation will exhibit the effect and develop an electrostatic model to estimate the critical thickness of the induced polarization in terms of basic material parameters. Our results provide practical guidelines for exploiting the electrostatic properties of thin-film ionic insulators to engineer novel functionalities for nanoscale devices.
Adsorption of the prototypical organic corrosion inhibitor benzotriazole on the Cu(100) surface
Turano, Marco; Walker, Marc; Grillo, Federico; et al. (2022)
Corrosion Science
The interaction of benzotriazole (BTAH) with Cu(100) has been studied as a function of BTAH exposure in a joint experimental and theoretical effort. Scanning tunnelling microscopy (STM), X-ray photoelectron spectroscopy (XPS), high resolution electron energy loss spectroscopy (HREELS) and density functional theory (DFT) calculations have been combined to elucidate the structural and chemical characteristics of this system. BTAH is found to deprotonate upon adsorption on the copper surface and to adopt an orientation that depends on the molecular coverage. Benzotriazolate (BTA) species initially lie with their planes parallel to the substrate but, at a higher molecular coverage, a transition occurs to an upright adsorption geometry. Upon increasing the BTAH exposure, different phases of vertically aligned BTAs are observed with increasing molecular densities until a final, self-limiting monolayer is developed. Both theory and experiment agree in identifying CuBTA and Cu(BTA)$_2$ metal-organic complexes as the fundamental building blocks of this monolayer. This work shows several similarities with the results of previous studies on the interaction of benzotriazole with other low Miller index copper surfaces, thereby ideally completing and concluding them. The overall emerging picture constitutes an important starting point for understanding the mechanism for protection of copper from corrosion.
Depolarizing-Field Effects in Epitaxial Capacitor Heterostructures
Strkalj, Nives; De Luca, Gabriele; Campanini, Marco; et al. (2019)
Physical Review Letters
Simulating Surfactant Iron Oxide Interfaces: From Density Functional Theory to Molecular Dynamics
Latorre, Carlos A.; Ewen, James P.; Gattinoni, Chiara; et al. (2019)
The Journal of Physical Chemistry B
Interface and surface stabilization of the polarization in ferroelectric thin films
Gattinoni, Chiara; Strkalj, Nives; Härdi, Rea; et al. (2020)
Proceedings of the National Academy of Sciences
In-situ monitoring of interface proximity effects in ultrathin ferroelectrics
Strkalj, Nives; Gattinoni, Chiara; Vogel, Alexander; et al. (2020)
Nature Communications
The development of energy-efficient nanoelectronics based on ferroelectrics is hampered by a notorious polarization loss in the ultrathin regime caused by the unscreened polar discontinuity at the interfaces. So far, engineering charge screening at either the bottom or the top interface has been used to optimize the polarization state. Yet, it is expected that the combined effect of both interfaces determines the final polarization state; in fact the more so the thinner a film is. The competition and cooperation between interfaces have, however, remained unexplored so far. Taking PbTiO3 as a model system, we observe drastic differences between the influence of a single interface and the competition and cooperation of two interfaces. We investigate the impact of these configurations on the PbTiO3 polarization when the interfaces are in close proximity, during thin-film synthesis in the ultrathin limit. By tailoring the interface chemistry towards a cooperative configuration, we stabilize a robust polarization state with giant polarization enhancement. Interface cooperation hence constitutes a powerful route for engineering the polarization in thin-film ferroelectrics towards improved integrability for oxide electronics in reduced dimension.
Water (Non-)Interaction with MoO3
Head, Ashley R.; Gattinoni, Chiara; Trotochaud, Lena; et al. (2019)
The Journal of Physical Chemistry C
Molybdenum(VI) oxide (MoO3) is used in a number of technical processes such as gas filtration and heterogeneous catalysis. In these applications, the adsorption and dissociation of water on the surface can influence the chemistry of MoO3 and thus the course of heterogeneous reactions. We use ambient pressure X-ray photoelectron spectroscopy to study the interaction of water with a stoichiometric MoO3 surface and a MoO3 surface that features oxygen defects and hydroxyl groups. The experimental results are supported by density functional theory calculations. We show that on a stoichiometric MoO3(010) surface, where Mo sites are unavailable, water adsorption is strongly disfavored. However, the introduction of surface species, which can interact with the lone pairs on the water O atom, e.g., Mo5+ atoms or surface OH groups, promotes water adsorption. Dissociation of water is favored at unsaturated Mo sites, i.e., at oxygen vacancies, while water adsorbs molecularly at hydroxyl sites.
Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces
Ewen, James P.; Ayestarán Latorre, Carlos; Gattinoni, Chiara; et al. (2020)
The Journal of Physical Chemistry C

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Chiara Gattinoni

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