Alessandro Fortunelli

Italian National Research Council | CNR · Pisa Research Area

Novel graphene-like nanomaterials with a non-zero bandgap are important for the design of gas sensors. The selectivity toward specific targets can be tuned by introducing appropriate functional groups on their surfaces. In this study, we use first-principles simulations, in the form of density functional theory (DFT), to investigate the covalent fu...

Platinum (Pt) nanocatalysts are essential for facilitating the cathodic oxygen reduction reaction in proton exchange membrane fuel cells but suffer from a trade-off between activity and durability. Here we present the design of a fine nanocatalyst comprising Pt nanoparticles with sparsely embedded cobalt oxide clusters (CoOx@Pt). This design exploi...

Assessing the accuracy of first-principles computational approaches is instrumental to predict electronic excitations in metal nanoclusters with quantitative confidence. Here we describe a validation study on the optical response of...

Current research regarding the efficiency of ultra‐light graphene aerogel (GA) energy dissipation is limited to quasi‐static tests and simulations. The lack of direct dynamical experiments has impeded its utilization in fields of energy dissipation. Therefore, in this study, the high dynamic energy dissipation capability of GA with ultra‐low densit...

Time‐dependent density functional theory (TDDFT) simulations are conducted on a series of chiral gold/silver alloy nanowires to explore whether silver doping can produce an enhancement of circular dichroism at the plasmon resonance in these systems, and to identify the quantum‐mechanical origin of the observed effects. We find a strong plasmonic di...

The surface configurations of the low-index facets of a set of spinel oxides are investigated using DFT+U calculations to derive surface energies and predict equilibrium nanoparticle shapes via the Wulff construction. Two very different conditions are investigated, corresponding to application either in heterogeneous catalysis or in electrocatalysi...

The surface configurations of the low-index facets of a set of spinel oxides are investigated using DFT+U calculations to derive surface energies and predict equilibrium nanoparticle shapes via the Wulff construction. Two very different conditions are investigated, corresponding to application either in heterogeneous catalysis or in electrocatalysi...

A chlorine‐doped ultrathin phase of hafnium disulfide (HfS2) is proposed as an ideal candidate material for 2D field‐effect transistor (FET) device applications, down to the extreme sub‐5 nm miniaturization limit. This transition metal dichalcogenide 2D material is designed to combine features of both a metal and a semiconductor, exhibiting a high...

We investigated carbon aerogel samples with super low densities of 0.013 g cm-3 (graphite is 2.5) and conducted compression experiments showing a very low yield stress of 5-8 kPa. To understand the atomistic mechanisms operating in these super low density aerogels, we present a computational study of the mechanical response of very low-density amor...

The surface configurations of the low-index facets of a set of spinel oxides are investigated using DFT+U calculations to derive surface energies and predict equilibrium nanoparticle shapes via the Wulff construction. Two very different conditions are investigated, corresponding to appli-cation either in heterogeneous catalysis or in electrocatalys...

In order to investigate Li2S as a potential protective coating for lithium anode batteries using superionic electrolytes, we need to describe reactions and transport for systems at scales of >10,000 atoms for time scales beyond nanoseconds, which is most impractical for quantum mechanics (QM) calculations. To overcome this issue, here, we first rep...

The Resolution of Identity (RI) technique has been employed to speed up the use of hybrid exchange-correlation (xc) functionals at the TDDFT level using the Hybrid Diagonal Approximation. The RI has been implemented within the polTDDFT algorithm (a complex damped polarization method) in the AMS/ADF suite of programs. A speedup factor of 30 has been...

In this work, we investigated cyclohexane oxidative dehydrogenation (ODH) catalyzed by cobalt ferrite nanoparticles supported on reduced graphene oxide (RGO). We aim to identify the active sites that are specifically responsible for full and partial dehydrogenation using advanced spectroscopic techniques such as X-ray photoelectron emission microsc...

We present a first-principles computational study of the NbS2/WSe2 junction between two transition metal dichalcogenide monolayers as a prototypical metal/semiconductor two-dimensional (2D) lateral heterostructure (LH) to investigate the effects of electrostatic perturbations on electron transport in 2D LH systems. In order to simulate electrostati...

We present a first-principles computational study of the NbS2/WSe2 junction between two transition metal dichalcogenide monolayers as a prototypical metal/semiconductor 2-dimensional (2D) lateral hetero-structure (LH) to investigate the effects of electrostatic perturbations on electron transport in 2D LH systems. In order to simulate electrostatic...

The water-soluble glutathione-protected [Au25(GSH)18]-1 nanocluster was investigated by integrating several methodologies such as molecular dynamics simulations, essential dynamics analysis, and state-of-the-art time-dependent density functional theory calculations. Fundamental aspects such as conformational, weak interactions and solvent effects,...

We present a first-principles computational study of the NbS2/WSe2 junction between two transition metal dichalcogenide monolayers as a prototypical metal/semiconductor 2-dimensional (2D) lateral hetero-structure (LH) to investigate the effects of electrostatic perturbations on electron transport in 2D LH systems. In order to simulate electrostatic...

We present a first-principles computational study of the NbS2/WSe2 junction between two transition metal dichalcogenide monolayers as a prototypical metal/semiconductor 2-dimensional (2D) lateral hetero-structure (LH) to investigate the effects of electrostatic perturbations on electron transport in 2D LH systems. In order to simulate electrostatic...

Monolayer MoS2 has attracted significant attention owing to its excellent performance as a n‐type semiconductor from the TMDC family. It is however strongly desired to develop controllable synthesis methods for 2D p‐type MoS2, which is crucial for complementary logic applications but remains difficult. In this work, we synthesize high‐quality NbS2‐...

Effects of the conformational dynamics of 2-PET protective ligands on the electronic circular dichroism (ECD) of the chiral Au38(SC2H4Ph)24 cluster are investigated. We adopt a computational protocol in which ECD spectra are calculated via the first principle polTDDFT approach on a series of conformations extracted from MD simulations by using Esse...

The structural stability of nanoalloys is a challenging research subject due to the complexity of size, shape, composition, and chemical ordering. The genetic algorithm is a popular global optimization method that can efficiently search for the ground-state nanoalloy structure. However, the algorithm suffers from three significant limitations: the...

For polymer electrolyte membrane fuel cells (PEMFCs), the state-of-the-art electrocatalysts are based on carbon-supported Pt group metals. However, current carbon supports suffer from carbon corrosion during repeated start-stop operations, causing performance degradation. We report a new strategy to produce highly graphitized carbon with controllab...

We present a computational study of the energetics and mechanisms of oxidation of Pt-Mn systems. We use slab models and simulate the oxidation process over the most stable (111) facet at a given Pt2Mn composition to make the problem computationally affordable, and combine Density-Functional Theory (DFT) with neural network potentials and metadynami...

Understanding the heat transfer mechanisms in bimetallic nanoparticles, e.g. to promote heat transfer in a nanofluid, is a significant problem for industrial and fluid mechanics related applications. Given the difficulties in interpreting experimental measurements, theoretical approaches to the prediction of thermal conductivity represent an altern...

A time-dependent density functional theory (TDDFT) computational approach is employed to study the optical coupling between a plasmonic system (a Ag50 nanorod) and a fluorescent dye (BODIPY). It is found that the BODIPY dye can interact with a plasmonic system in a rather different and selective way according to the mutual orientation of the fragme...

X-ray photoelectron spectroscopy (XPS) is a powerful surface analysis technique widely applied in characterizing the solid electrolyte interphase (SEI) of lithium metal batteries. However, experiment XPS measurements alone fail to provide atomic structures from a deeply buried SEI, leaving vital details missing. By combining hybrid ab initio and re...

Spinel ferrites, especially Nickel ferrite, NiFe2O4, and Cobalt ferrite, CoFe2O4, are efficient and promising anode catalyst materials in the field of electrochemical water splitting. Using density functional theory, we extensively investigate and quantitatively model the mechanism and energetics of the oxygen evolution reaction (OER) on the (001)...

A critical technological roadblock to the widespread adoption of proton-exchange membrane fuel cells is the development of highly active and durable platinum-based catalysts for accelerating the sluggish oxygen reduction reaction, which has largely relied on anecdotal discoveries so far. While the oxygen binding energy ∆EO has been frequently used...

Ultrasmall clusters of subnanometer size can possess unique and even unexpected physical and chemical propensities which make them interesting in various fields of basic science and for potential applications, such as catalysis, photocatalysis, electrocatalysis, and optical and chemical sensors, just to name a few examples. These small particles of...

We employ ab-initio density functional theory based method to investigate the ability of a subnanometer bimetallic Au19Pt cluster to adsorb and activate a CO2 molecule in an aqueous electrochemical environment. We find that, in water, Au19Pt gets negatively charged at zero bias and selectively promotes the adsorption and activation of the CO2 molec...

Low‐dimensional metal‐semiconductor vertical heterostructures (VH) are promising candidates in the search of electronic devices at the extreme limits of miniaturization. Within this line of research, here a theoretical/computational study of the NbS2/WSe2 metal‐semiconductor vertical hetero‐junction using density functional theory (DFT) and conduct...

We report a computational study at the time-dependent density functional theory (TDDFT) level of the chiro-optical spectra of chiral gold nanowires coupled in dimers. Our goal is to explore whether it is possible to overcome destructive interference in single nanowires that damp chiral response in these systems and to achieve intense plasmonic circ...

We report a computational study and analysis of the optical absorption processes of Ag20 and Au20 clusters deposited on the magnesium oxide (100) facet, both regular and including point defects. Ag20 and Au20 are taken as models of metal nanoparticles and their plasmonic response, MgO as a model of a simple oxide support. We consider oxide defects...

We propose the Augmented Grouping Approach (AugGA) and its deployment in the Augmented Grouping GO (AugGGO) scheme, for an efficient exploration of the chemical ordering (or compositional structure) of multi-component (alloyed) nanoparticles. The approach is based on a 'grouping' strategy (previously proposed for high-symmetry structures) by which...

We report a computational study via time-dependent density-functional theory (TDDFT) methods of the photo-absorption spectrum of an atomically precise monolayer-protected cluster (MPC), the Ag24Au(DMBT)18 single negative anion, where DMBT is the 2,4-dimethylbenzenethiolate ligand. The use of efficient simulation algorithms, i.e., the complex polari...

We report a combined experimental/theoretical approach to studying heterogeneous gas/solid catalytic processes using low-pressure pulse response experiments achieving a controlled approach to equilibrium that combined with quantum mechanics (QM)-based computational analysis provides information needed to reconstruct the role of the different surfac...

We report on the use of In as an effective H2 production promoter in a Cu/SiO2 catalyst for the steam reforming of methanol. To date, In promotion has been limited to noble metals because of its tendency to “bury” other metals thus compromising the catalytic activity. Here, we prepared a silica-supported Cu-In catalyst via a urea-assisted co-precip...

Correction for ‘2D oxides on metal materials: concepts, status, and perspectives’ by Giovanni Barcaro et al. , Phys. Chem. Chem. Phys. , 2019, 21 , 11510–11536, DOI: 10.1039/C9CP00972H.

Fluorescent atomically precise Ag38(11-azido-2-ol-undecane-thiolate)24 nanoclusters are easily prepared using sodium ascorbate as a "green"reducer and are extensively characterized by way of elemental analyses, ATR-FTIR, XRD, SAXS, UV-vis, fluorescence spectroscopies, and theoretical modeling. The fluorescence and the atomically determined stoichio...

Amorphous carbon systems are emerging to have unparalleled properties at multiple length scales, making them the preferred choice for creating advanced materials in many sectors, but the lack of long-range order makes it difficult to establish structure/property relationships. We propose an original computational approach to predict the morphology...

Food quality is of paramount importance for public health safety. For instance, fish freshness can be assessed by sensing the volatile short chain alkylamines produced by spoiled fish. Functionalized graphene is a good candidate for the design of gas sensors for such compounds and therefore of interest as the basic material in food quality sensor d...

We showed recently that the catalytic efficiency of ammonia synthesis on Fe-based nanoparticles (NP) for Haber–Bosch (HB) reduction of N₂ to ammonia depends very dramatically on the crystal surface exposed and on the doping. In turn, the stability of each surface depends on the stable intermediates present during the catalysis. Thus, under reaction...

In order to improve efficiency of ammonia synthesis using the Haber–Bosch (HB) process with Fe-based catalysts, we employed quantum mechanics (QM)-based hierarchical high-throughput catalyst screening (HHTCS) of 49 possible metal dopants. Here, we consider the Fe(211) surface (one of the two most active iron catalyst facets) to identify dopants tha...

A first‐principles theoretical study of a monolayer‐thick lateral heterostructure (LH) joining two different transition metal dichalcogenides, NbS2 and WSe2, is reported. The NbS2//WSe2 LH can be considered a prototypical example of a metal (NbS2)/semiconductor (WSe2) 2D hybrid heterojunction. First, realistic atomistic models of the NbS2//WSe2 LH...

Understanding the evolution of the structure and properties in metals from molecule-like to bulk-like has been a long sought fundamental question in science, since Faraday's 1857 work. We report the discovery of a Janus nanomolecule, Au191(SPh-tBu)66 having both molecular and metallic characteristics, explored crystallographically and optically and...

We probe the origin of photoluminescence of an atomically precise noble metal cluster, Ag24Au1(DMBT)18 (DMBT = 2,4-dimethylbenzenethiolate), and the origin of chirality in its chirally functionalized derivatives, Ag24Au1(R/S-BINAS) x (DMBT)18-2x, with x = 1-7 (R/S-BINAS = R/S-1,1'-[binaphthalene]-2,2'-dithiol), using chiroptical spectroscopic measu...

We report a first-principle theoretical study of a monolayer-thick lateral heterostructure (LH) joining two different transition metal dichalcogenides (TMDC): NbS2 and WSe2. The NbS2//WSe2 LH can be considered a prototypical example of a conducting(NbS2)/semiconducting(WSe2) two-dimensional (2D) hybrid heterojunction. We first generate and validate...

A hybrid approach able to perform Time Dependent Density Functional Theory (TDDFT) simulations with the same accuracy as that of hybrid exchange-correlation (xc-) functionals but at a fraction of the computational cost is developed, implemented, and validated. The scheme, which we name Hybrid Diagonal Approximation (HDA), consists in employing in t...

The Haber-Bosch (HB) process combining nitrogen (N₂) and hydrogen (H₂) into ammonia (NH₃) gases plays an essential role in the synthesis of fertilizers for food production and many other commodities. However, HB requires enormous energy resources (2% of world energy production) and the high pressures and temperatures make NH₃ production facilities...

Two-dimensional semiconductors are gaining increasing interest for their potential application in several fields. In particular, when combined with graphene into vertical van der Waals heterostructures, they have demonstrated unique properties, such as large spin–orbit coupling at the valence band maximum and ultra-fast charge transfer. Understandi...