Gianfranco Pacchioni

Gianfranco Pacchioni
Università degli Studi di Milano-Bicocca | UNIMIB · Department of Materials Science

PhD

About

680
Publications
50,832
Reads
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35,377
Citations
Introduction
Gianfranco Pacchioni currently works at the Department of Materials Science, Università degli Studi di Milano-Bicocca. Gianfranco does research in Materials Chemistry, Surface Chemistry and Theoretical Chemistry. Their current project is 'SMARTNESS - Solar driven chemistry: new materials for photo- and electro- catalysis'.
Additional affiliations
July 2010 - August 2010
University of North Texas
Position
  • Professor
June 2005 - June 2006
Fritz Haber Institute of the Max Planck Society
Position
  • Professor
January 1998 - present
Università degli Studi di Milano-Bicocca
Position
  • Professor (Full)

Publications

Publications (680)
Article
Full-text available
Tuning the properties of oxide surfaces through the adsorption of designed ligands is highly desirable for several applications, such as catalysis. N-Heterocyclic carbenes (NHCs) have been successfully employed as ligands for the modification of metallic surfaces. On the other hand, their potential as modifiers of ubiquitous oxide surfaces still ne...
Article
The most widely used approach to predict catalytic activity is density functional theory, whose results however depend on the adopted exchange‐correlation functional. In this work, the role played by the functional in predicting the activity of single atom catalysts (SAC) in the hydrogen and oxygen evolution reactions (HER and OER) is studied. 16 t...
Article
The characterization of catalytic oxide surfaces is often done by studying the properties of adsorbed probe molecules. The 31P NMR chemical shift of adsorbed trimethylphosphine, P(CH3)3 or TMP, has been used to identify the presence of different facets in oxide nanocrystals and to study the acid-base properties of the adsorption sites. The NMR stud...
Article
ConspectusSingle-atom catalysis (SAC) is a fascinating and rapidly growing field in heterogeneous catalysis. In less than 20 years, this has become one of the most widely investigated subjects by the catalytic community for various good reasons: the ability to synthesize active catalysts using a minimum amount of precious metals, the expected highe...
Article
We investigated the impact of quantum confinement on the band gap of chalcogenides 2D nanostructures by means of density functional theory (DFT). We studied six different systems: MoS 2 , WS 2 , SnS 2 , GaS, InSe, and HfS 2 and we simulated nanosheets of increasing thickness, ranging from ultrathin films to ~10-13 nm thick slabs, a size where the p...
Article
Single atom catalysts (SACs) consist of isolated metal atoms stabilized on a solid support. The name suggests that the catalytic activity is due to the nature of the metal atom, but of course the interaction with the substrate plays a role as well. But what is more important? The metal atom or its surrounding? To answer this question, we have perfo...
Preprint
The coupling of two sp3 hybridized fragments remains a challenging protocol for organic synthesis. Although visible light-driven dual photoredox catalysis, a method that combines photoabsorbers and transition metals, has become a powerful tool to conduct such transformations, resource economical and scalability issues persist, due to the use of cat...
Article
Full-text available
One of the objectives of electronic structure theory is to predict chemical and catalytic activities. This is a challenging target due to the large number of variables that determine the performance of a heterogeneous catalyst. The complexity of the problem has reduced considerably with the advent of single atom catalysts (SACs) and, in particular,...
Article
The global warming crisis has sparked a series of environmentally cautious trends in chemistry, allowing us to rethink the way we conduct our synthesis, and to incorporate more earth-abundant materials in our catalyst design. "Single-atom catalysis" has recently appeared on the catalytic spectrum, and has truly merged the benefits that homogeneous...
Article
N‐Heterocyclic carbenes (NHCs) have superior properties as building blocks of self‐assembled monolayers (SAMs). Understanding the influence of the substrate in the molecular arrangement is a fundamental step before employing these ligands in technological applications. Herein, we study the molecular arrangement of a model NHC on Cu(100) and Cu(111)...
Article
We present an approach to determine from first principles the expected efficiency of semiconductors heterojunctions in solar light absorption and electron-hole pairs generation for photocatalysis and solar cells applications. In a composite material, upon absorption of photons of appropriate wavelength, electrons and holes can migrate towards diffe...
Article
Full-text available
N‐Heterocyclic carbenes (NHCs) have superior properties as building blocks of self‐assembled monolayers (SAMs). Understanding the influence of the substrate in the molecular arrangement is a fundamental step before employing these ligands in technological applications. Herein, we study the molecular arrangement of a model NHC on Cu(100) and Cu(111)...
Article
Recently, Z-scheme systems have gained immense attention for application in photocatalytic hydrogen evolution (PHE). In this study, LaFeO3 perovskite (as photosystem II) was shelled by nitrogen-doped graphene (NGr as photosystem...
Article
Full-text available
The nature and local environment of Au single atoms supported and stabilized on four different oxides is studied by means of DFT + U calculations using CO as probe molecule and its stretching frequency, ω e , as a fingerprint of the site where the Au atom is bound. Four oxides are considered, anatase TiO 2 , tetragonal ZrO 2 , cubic CeO 2 , and a p...
Article
In the present work, we have studied the effect of iso-valent dopants on the chemical reactivity of the stoichiometric SnO2 (110) surface. Si, Ge, Pb, Ti, Zr, Hf, and Ce ions have been placed at the Sn lattice sites (substitutional doping) in bulk, sub-surface, and surface positions. The results show that surface or sub-surface sites are clearly pr...
Article
Full-text available
The hydrogen evolution reaction (HER) has a key role in electrochemical water splitting. Recently a lot of attention has been dedicated to HER from single atom catalysts (SACs). The activity of SACs in HER is usually rationalized or predicted using the original model proposed by Nørskov where the free energy of a H atom adsorbed on an extended meta...
Article
Europium, one of the rare-earth elements, exhibits +2 and +3 valence states and has been widely used for the magnetic modification of materials. Based on density functional theory calculations, we predicted 2D EuBr/graphene heterojunctions to exhibit metallicity, huge intrinsic-ferromagnetism nearly 7.0 μB per Eu and the special monovalent Eu ions....
Article
Supported plasmonic Au nanoclusters (NCs) consisting of a few tens of atoms can potentially offer great advantages for the light-driven hydrogen evolution reaction (HER). Here, we report on the synthesis of well-dispersed and stable plasmonic Au NCs of 0.5-1.0 nm size on nitrogen-doped high surface area graphene (N-Gr)viafreeze-drying and pyrolyzin...
Article
The electronic properties of N-doped ZnO/Cu(111) bilayer films have been studied by using the DFT+U method including dispersion contributions and compared to that of free-standing ZnO bilayer films. The substitution of a lattice O ion in free-standing ZnO bilayer by a N atom results in oxidation state of N of -2, while the oxidation state of N beco...
Article
In this brief account dedicated to the memory of Professor Renato Ugo I will trace the history of 40 years of research in cluster chemistry. I will describe how my research activity started in the early 1980s with studies inspired by the vision of Renato Ugo on the electronic structure of gas-phase Li clusters and their interaction with hydrogen mo...
Article
We studied the role of iso-valent heteroatoms replacing Ti4+ cations in the lattice of two titania polymorphs, rutile (r-) and anatase (a-) by means of first principles calculations. The r-TiO2(110) and the a-TiO2(101) surfaces have been considered and Ti ions in the bulk, sub-surface, and surface sites have been replaced with Si, Ge, Sn, Pb, Zr, H...
Article
Accurate electronic structure calculations have an increasingly importance to complement experimental characterization tools in the atomic‐scale design of semiconductor heterojunctions for photocatalysis. Pros and cons of various aspects that influence an accurate prediction of the offsets of valence and conduction bands, which is fundamental to im...
Article
Full-text available
The network structure of a silica bilayer film at a monolayer-bilayer transition and across a supporting metal step edge was studied at the atomic scale by scanning tunneling microscopy. The ring size distribution, ring-ring distances, and height profiles are analyzed across the step edge region. Density functional theory proposes two models to exp...
Article
Semiconductor heterojunctions are widely applied in solid-state device applications, including semiconductor lasers, solar cells, and transistors. In photocatalysis they are of interest due to their capability to hinder charge carriers' recombination. A key role in the performance of heterojunctions is that of the alignment of the band edges of the...
Preprint
Full-text available
Europium, one of the rare earth elements, exhibits +2 and +3 valence states and has been widely used for magnetic modification of materials. Based on density functional theory calculations, we predict the 2D EuBr/graphene heterojunctions to exhibit metallicity, huge intrinsic-ferromagnetism nearly 7.0 {\mu}B per Eu and the special monovalent Eu ion...
Article
Full-text available
Electronic structure calculations provide a useful complement to experimental characterization tools in the atomic‐scale design of semiconductor heterojunctions for photocatalysis. The band alignment of the heterojunction is of fundamental importance to achieve an efficient charge carriers separation, so as to reduce electron/hole recombination and...
Article
The properties of spherical 1-nm Pd43 nanoparticles confined between single layers of lepidocrocite-TiO2 are studied by means of Density Functional Theory calculations. Sandwich-like intercalation is then compared to the adsorption on a single oxide layer in terms of metal-oxide bond strength, structural distortion of the metal particle and charge...
Article
Full-text available
BiOIO3 photocatalysts exposing (010) and (100) surfaces show high efficiency in photocatalytic experiments thanks to an efficient charge separation: photogenerated electrons migrate to the (010) face, and holes move to the (100) one (F. Chen, et al.). However, if one considers the band alignment of the two thermodynamically most stable terminations...
Article
The role of the support in tuning the properties of transition metal (TM) atoms is studied by means of density functional theory calculations. We have considered the adsorption of Cu, Ag, Au, Ni, Pd, and Pt atoms on crystalline silica bilayers, either free-standing or supported on Ru(0001) and Pt(111) metal surfaces. These systems have been compare...
Article
Materials for post Li-ion batteries are attracting an increasing interest. Here we have studied the fundamental properties of multi-valent Al and Ca ions intercalated into V2O5 and MoO3 layered oxides. To this end we performed Density Functional Theory calculations using a Hubbard U correction for the electronic structure of the oxides and includin...
Preprint
Full-text available
Oxidation catalysis on reducible oxide-supported small metal clusters often involves lattice oxygen. In the present work, we trace the path of lattice oxygen from Fe3O4(001) onto small Pt clusters during the CO oxidation, aiming at differentiating whether the reaction takes place at the cluster/support interface or on the cluster. While oxygen vaca...
Article
The thinnest possible films of the glass‐forming materials silica and germania were so far investigatd by employing scanning probe microscopy and density functional theory calculations. A more general comprehension of the network structure of glass former materials allows to understand the crucial role of the metal support for the pathway from crys...
Article
α-CsPbX3 (X = Cl, Br, I) 2D nanostructures are widely used in solar cells, photocatalysis and photovoltaic applications, mainly because of their high efficiency in the conversion of solar energy. Based on hybrid Density Functional Theory (DFT) calculations we consider two aspects, (a) the role of surface termination, and (b) that of quantum size (t...
Chapter
In this chapter, we address the computational description of structural and electronic properties of TiO2. Particular emphasis is given to the key methodological aspects related to density functional theory calculations on titania. In particular, it is necessary to correctly account for the self-interaction error in the adopted functional in order...
Article
Composites formed by titania and graphitic C 3 N 4 , such as C 3 N 4 /TiO 2 and C 3 N 4 /SrTiO 3 /TiO 2 heterojunctions, have attracted a considerable interest in recent years as efficient photocatalysts. Experimental evidence shows that the charge...
Article
Correction for ‘Plasmonic Au nanoclusters dispersed in nitrogen-doped graphene as a robust photocatalyst for light-to-hydrogen conversion’ by Dung Van Dao et al. , J. Mater. Chem. A , 2021, DOI: 10.1039/D1TA05445G.
Article
Full-text available
Sometimes, dopants in oxide surfaces are referred to as single-atom catalysts, at least when these species are incorporated in the supporting lattice. Usually, single atom catalysts are transition metal atoms stabilized on an oxide surface, and the activity is due to the valence electrons of these species. However, the surface chemistry can be modi...
Article
Full-text available
Acid and basic sites on monoclinic and tetragonal zirconia were investigated at the DFT level by computing IR and NMR properties of adsorbed probe molecules. Regular and stepped ZrO2 surfaces as well as stoichiometric zirconia nanoparticles have been considered. Acidity and basicity were probed by the adsorption of carbon monoxide and pyrrole, resp...
Article
Full-text available
The growth of ZnO clusters supported by ZnO-bilayers on Ag(111) and the interaction of these oxide nanostructures with water have been studied by a multi-technique approach combining temperature-dependent infrared reflection absorption spectroscopy (IRRAS), grazing-emission X-ray photoelectron spectroscopy, and density functional theory calculation...
Article
In this work we investigate TiO2and BiVO4nanostructures by means of Density Functional Theory (DFT) calculations, to provide an estimate of the band alignment in TiO2/BiVO4interfaces, highly active in photo-electrochemistry and photocatalytic water splitting. Calculations were carried out with both DFT range separated and self-consistent dielectric...
Article
Full-text available
We report a systematic comparative dispersion-corrected DFT study of single (K, Au, and Pt) atoms adsorption over a wide range of metal-supported oxide ultrathin films (MgO on Ag and Mo, ZnO on Cu, Ag, and Au, SiO2 on Pt and Ru, TiO2 on Ag and Pt, ZrO2 on Pt and ZrPt). These films include reducible and non-reducible oxides, and have been prepared a...
Article
Full-text available
There is a crucial role of the metal-oxide interface in determining the growth of silica thin films. However, only a few metallic substrates have been explored so far. In previous studies, metal substrates exhibiting unreconstructed surfaces under oxygen exposure have been analyzed. In this work, we study the structure of a silica thin film grown o...
Article
Full-text available
The surface of oxide nanostructures (nanoparticles, nanowires, epitaxial thin films) can be significantly strained compared to the regular crystallographic surfaces. In this work, using DFT methods, we studied the dependence of properties of MgO(100), CaO(100), SrO(100), BaO(100), anatase TiO2(101) and tetragonal ZrO2(101) surfaces (band gap, work...
Article
In this work we investigate the role of quantum confinement in group III-V semiconductor thin films (2D nanostructures). To this end we have studied the electronic structure of nine materials (AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs and InSb) by means of Density Functional Theory (DFT) calculations using a screened-hybrid functional (HSE06). We...
Article
Full-text available
The present research article reports on the preparation and atomic‐scale characterization of the thinnest possible films of the glass‐forming materials silica and germania. To this end state‐of‐the‐art surface science techniques, in particular scanning probe microscopy, and density functional theory calculations have been employed. The investigated...
Article
Full-text available
The theoretical description of the electronic structure of magnetic insulators and, in particular, of transition-metal oxides (TMOs), MnO, FeO, CoO, NiO, and CuO, poses several problems due to their highly correlated nature. Particularly challenging is the determination of the band gap. The most widely used approach is based on density functional t...
Article
In this work, we investigate the structural and electronic properties of the SrTiO3/TiO2 (anatase) heterostructure by means of hybrid density functional theory calculations. The work is motivated by several experiments that pointed to SrTiO3/TiO2 as a good system for photocatalytic applications, due to the small lattice mismatch between these two o...
Article
Full-text available
Adsorption, desorption and fragmentation of Borazine on Pt(110) are studied by temperature-programmed desorption, ultraviolet photoemission spectroscopy, workfunction measurements and density functional theory. Borazine adsorbs in part dissociatively, forming an upright adsorption complex. Radicals with a N-Pt bond are weakly bound and desorb recom...
Article
When imaged by Scanning Tunneling Microscopy (STM) at constant current under non topographic conditions, nanosized MgO islands grown on Ag(100) may show a fractal dark internal structure and/or appear embedded in the surface. On the contrary, when imaged under topographic conditions, the same islands appear as nearly flat plateaus. Islands showing...
Article
Atomically dispersed metal catalysts have receieved recent interest, although the coordination of the metal to the support and how this is influenced by pre-treatment have not often been elucidated. We...
Article
The nature of a Rh single‐atom catalyst (SAC) stabilized on the surface of tetragonal zirconia, t‐ZrO 2 , is investigated here by performing extensive DFT calculations on various possible structural models and comparing the resulting spectral properties with existing data from the literature. The models considered include a Rh atom adsorbed on the...
Article
Composite materials whose band alignment induces a favourable separation of photogenerated electrons and holes often reveal a stronger photocatalytic activity compared to their separate components. As shown by experiments, titania composites display a heterojunction between the anatase (101)‐(001) surfaces, where the former stabilizes electrons and...
Article
Full-text available
The free-standing Au 20 cluster has a unique tetrahedral shape and a large HOMO-LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) gap of around 1.8 electron volts. The “magic” Au 20 has been intensively used as a model system for understanding the catalytic and optical properties of gold nanoclusters. However, direct rea...
Article
Full-text available
Calcium-molybdate ultrathin films were prepared on a Mo(001) crystal and characterized by means of scanning tunneling microscopy (STM), electron diffraction, photoelectron spectroscopy, and density functional theory (DFT). The films were grown via reactive Ca deposition, followed by a vacuum annealing step to trigger Mo diffusion from the support i...
Article
The surface basicity of the alkaline-earth metal oxides has been investigated by studying the properties of ¹⁷O nuclear magnetic resonance (NMR). To this end, we performed density functional theory calculations and determined the ¹⁷O chemical shift and the quadrupolar coupling constants of the regular and stepped surfaces of MO (M = Mg, Ca, Sr, and...
Article
Full-text available
Purely amorphous germania bilayer films are grown on a reconstructed Au(111) surface. The presence of the film affects the native configuration of the Au soliton walls, as observed with scanning tunneling microscopy. They partly avoid the film islands, and partly penetrate under film patches. This behavior indicates a weaker film-substrate interact...
Article
Full-text available
Oxide reducibility is an important property in catalysis by metal-oxides. The reducibility of an oxide can be substantially modified when an interface is created between the oxide and a metal. Here we discuss two types of interfaces. One consists of gold nanoparticles deposited on anatase TiO2 or tetragonal ZrO2 (101) surfaces; these are traditiona...
Article
The interaction of oxygen with Ce-ZrO2 (Ce ions diluted in the Zirconia matrix) is a key aspect for many applications of this material. In this work, for the first time, an unusual reversible interaction of the O2 molecule with the surface of this solid is reported. The joint use of Electron Paramagnetic Resonance (EPR) and Density Functional Theor...
Article
The reproduction of the band gap of semiconductors and insulators represents a well known problem for standard DFT approaches based on semi-local functionals. The problem can be partly solved using hybrid functionals where a given portion of exact exchange is mixed in with the DFT exchange. Recently, a new class of dielectric-dependent functional h...
Article
In this work we study the effect of nitrogen (N)-doping on the structural and electronic properties of coexposed anatase (001)-(101) surfaces by means of Density Functional Theory (DFT). This work is motivated by recent experiments, showing that these materials are highly active for photocatalysis. The introduction of doping species as N further im...
Article
Solid state 17O NMR is emerging as a new tool to characterize the nature of active sites on the surface of oxide materials. In particular, the identification and quantification of low-coordinated sites can provide useful information to assess the chemical properties and the chemical reactivity of oxide nanostructures. In this modeling study we have...
Article
The topic of production of useful chemical compounds with the help of solar light has been debated at a recent meeting organized in Rome on October 18 and 19, 2018, by the Accademia Nazionale dei Lincei. Some of the contributions presented at this event are collected in this special issue of the Rendiconti Lincei. Scienze fisiche e Naturali. In thi...