Miguel Lopez-Haro

Miguel Lopez-Haro
Universidad de Cádiz | UCA · Department of Material Science and Metallurgy Engineering and Inorganic Chemistry

Ph.D. in Chemistry

About

121
Publications
14,207
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,886
Citations
Citations since 2017
50 Research Items
2124 Citations
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
December 2012 - June 2013
University Joseph Fourier - Grenoble 1
Position
  • PostDoc Position
December 2010 - present
Atomic Energy and Alternative Energies Commission
Position
  • AC-(S)TEM
December 2010 - present
LEMMA
LEMMA
Position
  • PostDoc Position

Publications

Publications (121)
Article
Sub-nanometer Metal clusters have special physical and chemical properties, significantly different from those of nanoparticles. However, there is a major concern about their thermal stability and susceptibility to oxidation. In situ X-ray Absorption spectroscopy and Near Ambient Pressure X-ray Photoelectron spectroscopy results reveal that support...
Article
The oxygen stoichiometry of hollandite, KxMnO2-δ, nanorods has been accurately determined from a quantitative analysis of scanning-transmission electron microscopy (STEM) X-Ray Energy Dispersive Spectroscopy (XEDS) experiments carried out in chrono-spectroscopy mode. A methodology combining 3D reconstructions of high-angle annular dark field electr...
Article
Full-text available
Using a nanostructured platform (a controlled‐shape nano‐oxide) and conventional wet impregnation techniques, powder‐type materials have been prepared in which atomically thin surface layers are deposited under very mild conditions. More importantly, an advanced methodology, combining energy dispersive X‐ray spectroscopy‐scanning transmission elect...
Article
Full-text available
Finding simple, easily controlled, and flexible synthetic routes for the preparation of ternary and hybrid nanostructured semiconductors is always highly desirable, especially to fulfill the requirements for mass production to enable application to many fields such as optoelectronics, thermoelectricity, and catalysis. Moreover, understanding the un...
Article
Full-text available
Ligand-free sub-nanometer metal clusters (MCs) of Pt, Ir, Rh, Au and Cu, are prepared here in neat water and used as extremely active (nM) antitumoral agents for HeLa and A2870 cells. The preparation just consists of adding the biocompatible polymer ethylene-vinyl alcohol (EVOH) to an aqueous solution of the corresponding metal salt, to give liters...
Article
Full-text available
Oxygen mass transport in perovskite oxides is relevant for a variety of energy and information technologies. In oxide thin films, cation nonstoichiometry is often found but its impact on the oxygen transport properties is not well understood. Here, we used oxygen isotope exchange depth profile technique coupled with secondary ion mass spectrometry...
Article
Full-text available
Low atomicity clusters present properties dependent on the size, due to the quantum confinement, with well‐defined electronic structures and high stability. Here it is shown that Ag5 clusters catalyze the complete oxidation of sulfur to S⁺⁶. Ag5 catalytic activity increases with different oxidant species in the order O2 ≪ H2O2 < OH•. Selective oxid...
Article
Antitumoral Agents In article number 2113028, M. Arturo López‐Quintela, Fernando Domínguez, and co‐workers report that Ag5 clusters show unique catalytic activities to oxidize thiols. They catalyze the complete oxidation of thiols present in cysteine, glutathione, and thioredoxin. This oxidation is tunable by relevant biological oxidants species (h...
Article
Full-text available
Electron Tomography (ET) reconstructions can be analysed, via segmentation techniques, to obtain quantitative, 3D-information about individual nanoparticles in supported catalysts. This includes values of parameters out of reach for any other technique, like their volume and surface, which are required to determine the dispersion of the supported p...
Article
The assembly of atomically dispersed iron-nitrogen (FeN4) sites into graphitic structures is a promising approach for sustainable production of bifunctional electrocatalysts for oxygen electroreduction (ORR) and oxygen evolution (OER) reactions. In addition, single-atom FeN4 sites at the edges of carbon substrates provide higher electrocatalytic pe...
Article
Full-text available
Subnanometric metal species confined inside the microporous channels/cavities of zeolites have been demonstrated as stable and efficient catalysts. The confinement interaction between the metal species and zeolite framework has been proposed to play the key role for stabilization, though the confinement interaction is elusive to be identified and m...
Article
This paper presents new models for segmentation of 2D and 3D Scanning-Transmission Electron Microscope images based on the ordered median function. The main advantage of using this function is its good adaptability to the different types of images to be studied due to the wide range of weight vectors that can be cast. Classical segmentation models...
Article
Magnetic and conducting composites of cobalt ferrite nanoparticles and poly(aniline) have been synthesized in acid media by the oxidative polymerization of aniline in the presence of a dispersion of magnetic nanoparticles, using Fe(III) ions as an oxidizing agent. The materials have been characterized by X-ray diffraction studies, X-ray fluorescenc...
Article
Full-text available
The palladium-catalysed cross-coupling reaction between alkenes and aryl halides (the Mizoroki–Heck reaction) is a powerful methodology to construct new carbon–carbon bonds. However, the success of this reaction is in part hampered by an extremely marked regioselectivity on the double bond, which dictates that electron-poor alkenes react exclusivel...
Article
Full-text available
Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium si...
Preprint
Full-text available
Subnanometer-sized metal clusters often feature a molecule-like electronic structure, which makes their physical and chemical properties significantly different from those of nanoparticles and bulk material. Considering potential applications, there is a major concern about their thermal stability and susceptibility towards oxidation. Cu clusters o...
Preprint
Full-text available
Subnanometer-sized metal clusters often feature a molecule-like electronic structure, which makes their physical and chemical properties significantly different from those of nanoparticles and bulk material. Considering potential applications, there is a major concern about their thermal stability and susceptibility towards oxidation. Cu clusters o...
Article
Full-text available
Iron‐silica self‐organized membranes, so‐called chemical gardens, behave as fuel cells and catalyze the formation of amino‐/carboxylic acids and RNA nucleobases from organics that were available on early Earth. Despite their relevance for prebiotic chemistry, little is known about their structure and mineralogy at the nanoscale. Here we studied FIB...
Article
Full-text available
Iron‐silica self‐organized membranes, so‐called chemical gardens, behave as fuel cells and catalyze the formation of amino‐/carboxylic acids and RNA nucleobases from organics that were available on early Earth. Despite their relevance for prebiotic chemistry, little is known about their structure and mineralogy at the nanoscale. Here we studied FIB...
Article
The encapsulation of subnanometric metal entities (isolated metal atoms and metal clusters with a few atoms) in porous materials such as zeolites can be an effective strategy for the stabilization of those metal species and therefore can be further used for a variety of catalytic reactions. However, owing to the complexity of zeolite structures and...
Article
To achieve high-loading of stable subnanometric metal clusters on solid carriers is a challenge since those small metal clusters have strong tendency to sinter into larger nanoparticles. Development of facile synthesis methodologies to obtain subnanometric metal catalysts with high metal loading and high stability against sintering at high temperat...
Article
Full-text available
Modulating the structures of subnanometric metal clusters at the atomic level is a great synthetic and characterization challenge in catalysis. Here, we show how the catalytic properties of subnanometric platinum clusters (0.5–0.6 nm) confined in the sinusoidal 10R channels of purely siliceous MFI zeolite are modulated upon introduction of partiall...
Article
Isolated iridium atoms and subnanometric iridium clusters are regioselectively generated and stabilized in the 10MR window of MWW zeolite for shape‐selective activation of alkanes. Abstract Preparation of supported metal catalysts with uniform particle size and coordination environment is a challenging and important topic in materials chemistry an...
Article
Preparation of supported metal catalysts with uniform particle size and coordination environment is a challenging and important topic in materials chemistry and catalysis. In this work, we report the regioselective generation of single‐site Ir atoms and their evolution into stabilized subnanometric Ir clusters in MWW zeolite, which are located at t...
Article
A novel procedure to optimize the 3D morphological characterization of nanomaterials by means of high angle annular dark field scanning‐transmission electron tomography is reported and is successfully applied to the analysis of a metal‐ and halogen‐free ordered mesoporous carbon material. The new method is based on a selection of the two parameters...
Article
Full-text available
Ordered mesoporous cerias were synthesised by employing metal- and halogen- free ordered mesoporous carbons (OMCs) as the hard templates in a ‘nanocasting’ procedure. TEM, small angle (SA) and wide angle (WA) XRD, and N2 physisorption analyses were used to characterise the templates, intermediates and ceria products and electron tomography (STEM-HA...
Article
Agrochemical encapsulation agents used up to now are commonly based on polymeric compounds or metal particles, but the employment of other natural products as host structure has not been tackled in detail. In the work reported here, fully-organic nanotubes composed by a human bile acid (lithocholic acid) has been synthesized. These nanotubes were e...
Article
Gold nanoparticles of different shapes (spherical, rods, and prisms) aggregate when deposited onto Lactobacillus fermentum's exopolysaccharide (EPS), a set of polysaccharides excreted by the bacteria. Transmission electron microscopy studies revealed that gold nanoparticles have high affinity for EPS. UV-vis spectra of aggregated gold nanoparticles...
Article
Full-text available
Subnanometric metal species (single atoms and clusters) have been demonstrated to be unique compared with their nanoparticulate counterparts. However, the poor stabilization of subnanometric metal species towards sintering at high temperature (>500 °C) under oxidative or reductive reaction conditions limits their catalytic application. Zeolites can...
Article
Multifunctional materials working under solely visible-light are expected to play a significant role in photo-electronics, in particular photo-switches, photo-optical sensors, smart windows, displays, optical storage memories, and self-cleaning materials. We have modified the surface of a versatile semiconductor material (TiO2) with a noble metal (...
Article
Redox and catalytic performance in total methane oxidation of a nanostructured ceria-terbia catalyst supported on magnesia is presented and compared to that of a pure ceria catalyst supported on MgO. The investigated material, Ce0.5Tb0.5Ox (3% mol.)/MgO, features several remarkable properties: a quite low total molar loading of the two lanthanide e...
Article
Ferritin, a soluble and highly robust protein with subunits packed into well-defined helices, is a key component of the iron regulatory system in the brain and thus is widely recognized as a crucial protein for iron metabolism, but may also bear possible implications in some neurodegenerative disorders. Here, we present evidence of how human recomb...
Preprint
Multifunctional materials working under solely visible-light are expected to play a significant role in photo-electronics, in particular photo-switches, photo-optical sensors, smart windows, displays, optical storage memories, and self-cleaning materials. In this work, we have modified the surface of a versatile semiconductor material (TiO<sub>2</s...
Article
Full-text available
This paper explores the capability of scanning transmission electron microscopy (STEM) techniques in determining the dispersion degree of graphene layers within the carbon matrix by using simulated high-angle annular dark-field (HAADF) images. Results ensure that unmarked graphene layers are only detectable if their orientation is parallel to the m...
Article
In this work we analyze two series of samples containing tungsten and titania as cations with a W/Ti atomic ratio from 0 to 0.5. The samples are prepared by a single-pot procedure, rendering in all cases high surface area powders having a dominant anatase crystalline phase. The materials were characterized by a combination of X-ray diffraction and...
Article
The synthesis and reactivity of single metal atoms in low–valence state bound to just water, rather than to organic ligands or surfaces, is a major experimental challenge. Here, we show a gram–scale wet synthesis of Pt11+ stabilized in a confined space by a well–defined crystallographic first water sphere, and with a second coordination sphere link...
Article
The synthesis and reactivity of single metal atoms in low–valence state bound to just water, rather than to organic ligands or surfaces, is a major experimental challenge. Here, we show a gram–scale wet synthesis of Pt11+ stabilized in a confined space by a well–defined crystallographic first water sphere, and with a second coordination sphere link...
Article
Cation exchange reactions have been exploited in the last years as an efficient tool for the controlled chemical modification of pre-made nanocrystals. In this work, the gradual transformation of non-toxic Ag2S nanocrystals into Au2S analogues is performed by sequential cation exchange reactions that allow for a fine control of the chemical composi...
Conference Paper
Full-text available
Fe-silica self-organized membranes, so-called Fe-silica gardens, are film-like or twisted hollow filamentous structures that form upon reaction of an alkaline silica-rich solution/salt with an Fe-rich acidic solution/salt [1]. These membranes exhibit a series of interesting properties relevant for prebiotic chemistry [2,3], life detection studies a...
Article
The gram‐scale synthesis, stabilization and characterization of well‐defined ultrasmall subnanometric catalytic clusters on solids represent a challenge. Here, we report the chemical synthesis and X‐ray snapshots of Pt20 clusters, homogenously distributed and densely‐packaged within the channels of a metal‐organic framework. This novel hybrid mater...
Article
The gram‐scale synthesis, stabilization and characterization of well‐defined ultrasmall subnanometric catalytic clusters on solids represent a challenge. Here, we report the chemical synthesis and X‐ray snapshots of Pt20 clusters, homogenously distributed and densely‐packaged within the channels of a metal‐organic framework. This novel hybrid mater...
Article
Full-text available
Inorganic molten salts are known as fluxes for the synthesis of novel bulk inorganic compounds and of mesostructures and nanostructures with crystal habits different from those observed in more conventional solvents. However, they have not demonstrated the ability to provide mesostructures and nanostructures of complex metal oxides that are current...
Article
A 3D nanometrological approach, which considers as an unbiased validation criterion the quantitative match between values of properties determined by macroscopic characterization techniques and those determined from the nanoscopic results, is developed to unveil the details of complex nanocatalysts. This approach takes into account both the peculia...
Article
Nanoencapsulation has proven to be an efficient route to increase significantly the solubility and bioavailability of organic compounds. This aspect of nanotechnology is illustrated for the case of phthalimide-lactone (PL), a recently synthesized strigolactone mimic whose very limited solubility in water, as a free chemical, precludes its practical...
Article
Due to electrical conductivity, specific surface area, pore size distribution and chemical inertness requirements, the replacement of high surface area carbon supports used in proton-exchange membrane fuel cells is challenging. In this context, tin dioxide (SnO2, TO) based materials have already shown promises but their long-term stability in the v...
Article
Nature uses enzymes to dissociate and transfer H2 by combining Fe²⁺ and H⁺ acceptor/donor catalytic active sites. Following a biomimetic approach, it is reported here that very small planar Fe2,3+ oxide nanoparticles (2.0 ± 0.5 nm) supported on slightly acidic inorganic oxides (nanocrystalline TiO2, ZrO2, ZnO) act as bifunctional catalysts to disso...
Poster
Semiconductor nanowires (NWs) are promising candidates for many device applications ranging from electronics and optoelectronics to energy conversion and spintronics. However, typical NW devices are fabricated using electron beam lithography and therefore source, drain and channel length still depend on the spatial resolution of the lithography. In...
Chapter
Ceria nanoparticles exhibiting controlled morphologies have been studied as model supports of gold nanoparticles to establish correlations between surface crystallography and catalytic performance [1]. It is generally assumed that the contacts between Au nanoparticles and support involve the expected ones, i.e. Au//CeO2 {100} in the case of nanocub...
Article
Full-text available
The enhancement of the performance of advanced nitride-based optoelectronic devices requires the fine tuning of their composition, which has to be determined with a high accuracy and at the nanometer scale. For that purpose, we have evaluated and compared energy dispersive X-ray spectroscopy (EDX) in a scanning transmission electron microscope (STE...
Chapter
3D quantitative characterization of metal catalysts supported on heavy oxides by High Angle Annular Dark Field (HAADF) STEM electron tomography (ET) is a very challenging task. Noble metal nanoparticles (Au, Ru) supported on ceria or ceria mixed oxides illustrates the case. The difference, very small in some cases, between the atomic number (Z) of...
Article
Temperature sensing in biological media (cells, tissues, and living organisms) has become essential in the development of the last generation of diagnostics and therapeutic strategies. Thermometry can be used for early detection of different diseases, such as cancer, stroke, or inflammation processes, one of whose incipient symptoms is the appearan...
Conference Paper
We report here on the quantitative 3D reconstruction of core-shell nanostructures by STEM/EDX using two X-ray maps acquired at two different tilt angles perpendicular to each other (Rueda et al., 2016; fig. 1). The method is based on the modelling of the NW cross-section using a series of imbricated ellipses whose dimensions are defined by their ma...
Article
div class="title">Contribution of Transmission Electron Microscopy to Proton Exchange Membrane Fuel Cell Electrodes Development and Degradation Understanding - Volume 22 Issue S3 - Laure Guétaz, Miguel Lopez-Haro, Pascale Bayle-Guillemaud, Arnaud Morin, Sylvie Escribano
Article
Using a method that combines experimental and simulated Aberration-Corrected High Resolution Electron Microscopy images with digital image processing and structure modeling, strain distribution maps within gold nanoparticles relevant to real powder type catalysts, i.e. smaller than 3 nanometers, and supported on a ceria-based mixed oxide have been...
Article
Energy dispersive x-ray spectrometry is used to extract a quantitative 3D composition profile of heterostructured nanowires. The analysis of hypermaps recorded along a limited number of projections, with a preliminary calibration of the signal associated to each element, is compared to the intensity profiles calculated for a model structure with su...
Article
A novel CeO2/MgO catalyst with low ceria loading has been synthesized. This catalyst showed unique redox properties compared with conventional high and low surface area CeO2. Advanced (scanning) transmission electron microscopy techniques revealed the presence of a variety of highly dispersed ceria nanostructures: isolated CeOx entities, CeO2 clust...
Article
Investigation of membrane/electrode assembly (MEA) microstructure has become an essential step to optimize the MEA components and manufacturing processes or to study the MEA degradation. For these investigations, transmission electron microscopy (TEM) is a tool of choice as it provides direct imaging of the different components. TEM is then widely...
Article
tert-butylthiol (tBuSH) is used as the sulphur source, surface ligand and co-solvent in the synthesis of CuInS2 nanocrystals (NCs). The presented method gives directly access to short-ligand capped NCs without post-synthetic ligand exchange. The obtained 5-nm CuInS2 NCs crystallize in the cubic sphalerite phase with space group F-43m and a lattice...
Article
Hollow nanomaterials composed of a Pt-rich shell surrounding a central void have demonstrated promising electrocatalytic activity for the oxygen reduction reaction (ORR). However, their long-term stability remains understudied, and is the focus of the present paper. Here, we followed the temperature-dependent morphological and compositional traject...
Article
Tin sulfide nanoparticles have a great potential for use in a broad range of applications related to solar energy conversion (photovoltaics, photocatalysis), electrochemical energy storage and thermoelectrics. The development of chemical synthesis methods allowing for the precise control of size, shape, composition and crystalline phase is essentia...
Article
Investigation of membrane/electrode assembly (MEA) microstructure has become an essential step to optimize the MEA manufacturing processes or to study the degradation of the different MEA components. Transmission electron microscopy (TEM) is a tool of choice as it provides direct imaging of the different components. TEM is then widely used for anal...
Article
In this letter we report on the exploration, of axial metal/semiconductor (Al/Ge) nanowire heterostructures with abrupt interfaces. The formation process is enabled by a thermal induced exchange reaction between the vapor-liquid-solid grown Ge nanowire and Al contact pads due to the substantially different diffusion behavior of Ge in Al and vice ve...
Article
A partial transformation of the {100} surfaces of ceria nanocubes into a set of nanometer-heighted, {111}-bounded, peaks was achieved by an oxidation treatment at 600 ºC. This particular type of surface nanostructuration allows to preparing CeO2 nanoparticles in which {111} nanofacets contribute significantly to their surface crystallography. This...
Article
The nanoscale morphology of highly active Pt3Ni7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by h...
Article
Full-text available
Proton exchange membrane fuel cell is one of the most promising zero-emission power sources for automotive or stationary applications. However, their cost and lifetime remain the two major key issues for a widespread commercialization. Consequently, much attention has been devoted to optimizing the membrane/electrode assembly that constitute the fu...
Article
Full-text available
Long-term catalytic performance of electrode materials is a well-established research priority in electrochemical energy conversion and storage systems, such as proton-exchange membrane fuel cells. Despite extensive efforts in research and development, Pt-based nanoparticles remain the only – but unstable – electrocatalyst able to accelerate effici...