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Catalytic cancer therapy targets cancer cells by exploiting the specific characteristics of the tumor microenvironment (TME). TME-based catalytic strategies rely on the use of molecules already present in the TME. Amino groups seem to be a suitable target, given the abundance of proteins and peptides in biological environments. Here we show that catalytic CuFe2O4 nanoparticles are able to foster transaminations with different amino acids and pyruvate, another key molecule present in the TME. We observed a significant in cellulo decrease in glutamine and alanine levels up to 48 h after treatment. In addition, we found that di- and tripeptides also undergo catalytic transamination, thereby extending the range of the effects to other molecules such as glutathione disulfide (GSSG). Mechanistic calculations for GSSG transamination revealed the formation of an imine between the oxo group of pyruvate and the free −NH2 group of GSSG. Our results highlight transamination as alternative to the existing toolbox of catalytic therapies.

In the frame of designing eco-friendly chemical processes, solvents represent a crucial economic and environmental concern. Compressed carbon dioxide (CO2) is an alternative green solvent for many industrial applications. Herein, we present the most relevant aspects of using compressed CO2 in metal-catalyzed hydrogenation reactions. In the first part, we discuss engineering fundamentals for the description of processes in supercritical fluids, gas-expanded liquids, continuous-flow applications and process design, including safety aspects and examples of heterogeneous catalysis. In the second part, we focus on catalytic systems based on both metal complexes and nano-systems, emphasizing how the catalysts have been adapted to the specificity of CO2. For this purpose, significant aspects such as the catalyst design, the reaction conditions and the use of co-solvents are considered. The main goal of this review is to show the advantages of using this green solvent in catalytic hydrogenations, including a critical analysis concerning its limitations.

Heterogeneous catalysis has emerged as a promising alternative for the development of new cancer therapies. In addition, regarding the tumor microenvironment as a reactor with very specific chemical features has provided a new perspective in the search for catalytic nanoarchitectures with specific action against chemical species playing a key role in tumor metabolism. One of these species is glutathione (GSH), whose depletion is the cornerstone of emerging strategies in oncology, since this metabolite plays a pivotal regulatory role as antioxidant agent, dampening the harmful effects of intracellular reactive oxidative species (ROS). Herein, we present copper-iron oxide spinel nanoparticles that exhibit a versatile and selective catalytic response to reduce GSH levels while generating ROS in a cascade reaction. We demonstrate a clear correlation between GSH depletion and apoptotic cell death in tumor cells in the presence of the copper-iron nanocatalyst. Furthermore, we also provide a novel analytical protocol, alternative to state-of-the-art commercial kits, to accurately monitoring the concentration of GSH intracellular levels in both tumor and healthy cells. We observe a selective action of the nanoparticles, with lower toxicity in healthy cell lines, whose intrinsic GSH levels are lower, and intense apoptosis in tumor cells accompanied by a fast reduction of GSH levels.

The stabilisation of metal nanoparticles and control of their oxidation state are crucial factors in nanocatalysis. Elemental sulfur has been found to be a cheap and effective stabilising agent for copper nanoparticles in the form of copper(I) oxide. The Cu2ONPs/S8 system has been characterised by ICP-OES, EDX, XRD, XPS, FE-SEM, SEM, TEM and Cryo-EM. Astonishingly, in organic medium, the copper nanoparticles are organised as concentric rings within nanodroplets of sulfur of ca. 20–70 nm. In synthetic organic chemistry, imines can be directly obtained by the less studied and practiced oxidation of primary amines; however, the reaction conditions utilised are usually harsh and far from meeting the principles of Green Chemistry. Cu2ONPs/S8 has been successfully applied to the solvent-free aerobic oxidation of primary amines to imines under ambient conditions, using air as a terminal oxidant. The catalyst is effective in the homo- and heterocoupling of benzylic amines at very low copper loading (0.3 mol%), being catalytically superior to a range of commercial copper catalysts. A reaction mechanism has been proposed based on experimental evidence, which clarifies the major uncertainty regarding the key intermediate. The results of this study suggest a number of new avenues for research in nanocatalysis.

The stabilisation of metal nanoparticles and control of their oxidation state are crucial factors in nanocatalysis. Elemental sulfur has been found to be a cheap and effective stabilising agent for copper nanoparticles in the form of copper(I) oxide. The Cu2ONPs/S8 system has been characterised by ICP-OES, EDX, XRD, XPS, FE-SEM, SEM, TEM and Cryo-EM. Astonishingly, in organic medium, the copper nanoparticles are organised as concentric rings within nanodroplets of sulfur of ca. 20–70 nm. In synthetic organic chemistry, imines can be directly obtained by the less studied and practiced oxidation of primary amines; however, the reaction conditions utilised are usually harsh and far from meeting the principles of Green Chemistry. Cu2ONPs/S8 has been successfully applied to the solvent-free aerobic oxidation of primary amines to imines under ambient conditions, using air as a terminal oxidant. The catalyst is effective in the homo- and heterocoupling of benzylic amines at very low copper loading (0.3 mol%), being catalytically superior to a range of commercial copper catalysts. A reaction mechanism has been proposed based on experimental evidence, which clarifies the major uncertainty regarding the key intermediate. The results of this study suggest a number of new avenues for research in nanocatalysis.

The material characteristics and properties of transition metal dichalcogenide (TMDCs) have gained research interest in various fields, such as electronics, catalytic, and energy storage. In particular, many researchers have been focusing on the applications of TMDCs in dealing with environmental pollution. TMDCs provide a unique opportunity to develop higher-value applications related to environmental matters. This work highlights the applications of TMDCs contributing to pollution reduction in (i) gas sensing technology, (ii) gas adsorption and removal, (iii) wastewater treatment, (iv) fuel cleaning, and (v) carbon dioxide valorization and conversion. Overall, the applications of TMDCs have successfully demonstrated the advantages of contributing to environmental conversation due to their special properties. The challenges and bottlenecks of implementing TMDCs in the actual industry are also highlighted. More efforts need to be devoted to overcoming the hurdles to maximize the potential of TMDCs implementation in the industry.

The material characteristics and properties of transition metal dichalcogenide (TMDCs) have gained research interest in various fields, such as electronics, catalytic, and energy storage. In particular, many researchers have been focusing on the applications of TMDCs in dealing with environmental pollution. TMDCs provide a unique opportunity to develop higher-value applications related to environmental matters. This work highlights the applications of TMDCs contributing to pollution reduction in (i) gas sensing technology, (ii) gas adsorption and removal, (iii) wastewater treatment, (iv) fuel cleaning, and (v) carbon dioxide valorization and conversion. Overall, the applications of TMDCs have successfully demonstrated the advantages of contributing to environmental conversation due to their special properties. The challenges and bottlenecks of implementing TMDCs in the actual industry are also highlighted. More efforts need to be devoted to overcoming the hurdles to maximize the potential of TMDCs implementation in the industry.

The material characteristics and properties of transition metal dichalcogenide (TMDCs) have gained research interest in various fields, such as electronics, catalytic, and energy storage. In particular, many researchers have been focusing on the applications of TMDCs in dealing with environmental pollution. TMDCs provide a unique opportunity to develop higher-value applications related to environmental matters. This work highlights the applications of TMDCs contributing to pollution reduction in (i) gas sensing technology, (ii) gas adsorption and removal, (iii) wastewater treatment, (iv) fuel cleaning, and (v) carbon dioxide valorization and conversion. Overall, the applications of TMDCs have successfully demonstrated the advantages of contributing to environmental conversation due to their special properties. The challenges and bottlenecks of implementing TMDCs in the actual industry are also highlighted. More efforts need to be devoted to overcoming the hurdles to maximize the potential of TMDCs implementation in the industry.

The material characteristics and properties of transition metal dichalcogenide (TMDCs) have gained research interest in various fields, such as electronics, catalytic, and energy storage. In particular, many researchers have been focusing on the applications of TMDCs in dealing with environmental pollution. TMDCs provide a unique opportunity to develop higher-value applications related to environmental matters. This work highlights the applications of TMDCs contributing to pollution reduction in (i) gas sensing technology, (ii) gas adsorption and removal, (iii) wastewater treatment, (iv) fuel cleaning, and (v) carbon dioxide valorization and conversion. Overall, the applications of TMDCs have successfully demonstrated the advantages of contributing to environmental conversation due to their special properties. The challenges and bottlenecks of implementing TMDCs in the actual industry are also highlighted. More efforts need to be devoted to overcoming the hurdles to maximize the potential of TMDCs implementation in the industry.

At the industrial level, Ag catalysts in the form of silver crystals held by a silver gauze are largely used for formaldehyde production and ethylene epoxidation. These self-supported structures undergo surface reconstructions and morphological changes upon exposure to moderately high temperatures (473–900 K) and oxidising atmospheres. These phenomena have been studied and well understood on single crystal surfaces and polycrystalline foils: different oxygen surface and sub-surface species have been identified and reconstruction processes explained. To verify the scalability of the surface science results and ultimately understand these phenomena on catalysts at the industrial scale, further studies on more complex samples are needed. Attempts to close this “materials gap” have been carried out in this present study where experiments have been performed on model single catalytic nanoparticles, i.e. the apexes of field emitter tips, using both field emission (FE) and field ion (FI) microscopies. Pure Ag samples are exposed to a pressure of 3 × 10–5 mbar of O2 at temperatures up to 700 K. These conditions reflect those used on the industrial scale. Important surface/morphological reconstructions are observed both in FE and FI modes. For comparison, experiments have been repeated on Au-8.8%at. Ag field emitter tips, representative samples for Au–Ag catalytic nanofoams, using to 3 × 10–5 mbar of NO2 at temperatures up to 450 K. Similar behaviour are observed and the influence of the oxidising gas is discussed., SCOPUS: ar.j, info:eu-repo/semantics/published

The oxygen adsorption and its catalytic reaction with hydrogen on Pt–Rh single crystals were studied at the nanoscale by Field Emission Microscopy (FEM) and Field Ion Microscopy (FIM) techniques at 700 K. Both FEM and FIM use samples prepared as sharp tips, apexes of which mimic a single nanoparticle of catalyst considering their similar size and morphology. Oxygen adsorption on Pt-17.4 at.%Rh samples leads to the formation of subsurface oxygen, which is manifested in the field emission (FE) patterns: for O2 exposure of ~3 Langmuir (L), {113} planes appear bright in the emission pattern, while for higher oxygen doses, i.e. 84 L, the bright regions correspond to the high index planes between the {012} and {011} planes. Formation of subsurface oxygen is probably accompanied by a surface reconstruction of the nanocrystal. The subsurface oxygen can be effectively reacted off by subsequent exposure of the sample to hydrogen gas at 700 K. The hydrogenation reaction was observed as a sudden, eruptive change of the brightness seen on the FE pattern. This reaction resulted in the recovery of the initial field emission pattern characteristic of a clean tip, with {012} facets being the most visible. It was shown that the oxygen accumulation-reduction process is completely reversible. The obtained results indicate that the presence of subsurface species must be considered in the description of reactive processes on Pt–Rh catalysts., SCOPUS: ar.j, info:eu-repo/semantics/published

Worldwide efforts have been focused to introduce greener chemical and energetic processes that drive the society away from the dependency on fossil fuels, looking to reduce the environmental footprint of modern societies. Catalysis for instance, has been for decades the winning technology which helps to improve the efficiency of processes in petrochemical, pharmaceutical, and biomedical industries to mention a few. Efficiency of catalysts come mostly from its structure and composition which proportionate high activity and selectivity. However, the use of expensive noble metals as catalyst materials remains a key issue for industrial applications. Thus, developing materials that reduce and mitigate carbon dioxide emissions as well as decrease of waste of the materials using during these processes remain a tremendous challenge to overcome. Nanotechnology for instance, is a growing technology with great impact in the industrial,pharmaceutical and energetical sectors. In fact, nanomaterials provide a better economical option, less waste and still with superior performance than their bulk counterparts which is explained from their reduce size, shape and larger surface areas which leads to overall higher catalytic performance. Nanocatalysis modify the rate of a chemical reaction by speeding up or accelerating the reaction rate without being consumed, making the process more energetically favored. Nanocatalyst have significant impact in different industrial processes as chemical reactions to produce fine chemicals, or for renewable energy and among others. As it was mentioned previously, the high performance of nanocatalyst is associated with the atoms at the surface of the nanostructure which are known as the active sites for catalysis. Moreover, it is well known that surface atoms placed at the corner or edges of the nanocatalyst are more active than those surface atoms at planes, and it the same manner with surface-to-volume ratio, their number will increase with decrea

Worldwide efforts have been focused to introduce greener chemical and energetic processes that drive the society away from the dependency on fossil fuels, looking to reduce the environmental footprint of modern societies. Catalysis for instance, has been for decades the winning technology which helps to improve the efficiency of processes in petrochemical, pharmaceutical, and biomedical industries to mention a few. Efficiency of catalysts come mostly from its structure and composition which proportionate high activity and selectivity. However, the use of expensive noble metals as catalyst materials remains a key issue for industrial applications. Thus, developing materials that reduce and mitigate carbon dioxide emissions as well as decrease of waste of the materials using during these processes remain a tremendous challenge to overcome. Nanotechnology for instance, is a growing technology with great impact in the industrial,pharmaceutical and energetical sectors. In fact, nanomaterials provide a better economical option, less waste and still with superior performance than their bulk counterparts which is explained from their reduce size, shape and larger surface areas which leads to overall higher catalytic performance. Nanocatalysis modify the rate of a chemical reaction by speeding up or accelerating the reaction rate without being consumed, making the process more energetically favored. Nanocatalyst have significant impact in different industrial processes as chemical reactions to produce fine chemicals, or for renewable energy and among others. As it was mentioned previously, the high performance of nanocatalyst is associated with the atoms at the surface of the nanostructure which are known as the active sites for catalysis. Moreover, it is well known that surface atoms placed at the corner or edges of the nanocatalyst are more active than those surface atoms at planes, and it the same manner with surface-to-volume ratio, their number will increase with decrea

The combination of metal nanoparticles (Pd or Pt NPs) with NAD-dependent thermostable alcohol dehydrogenase (TADH) resulted in the one-flask catalytic double reduction of 3-methyl-2-cyclohexenone to 3-(1S,3S)-methylcyclohexanol. In this article some assumptions about the interactions between a chemocatalyst and a biocatalyst have been proposed. It was demonstrated that the size of the NPs was the critical parameter for the mutual inhibition: the bigger the NPs the more harmful for the enzyme they were even if the NPs themselves were only moderately inactivated. Conversely the smaller the NPs the more minimal the TADH denaturation although they were dramatically inhibited. Resuming the chemocatalysts were very sensitive to deactivation which was not related to the amount of enzyme used while the inhibition of the biocatalyst can be strongly reduced by minimizing the NPs/TADH ratio used to catalyze the reaction. Among some methods to avoid direct binding of NPs with TADH we found that using large Pd NPs and protecting their surfaces with a silica shell the overall yield of 3-(1S,3S)-methylcyclohexanol was maximized (36%)., BT/Biocatalysis

Multifunctional nanoreactors are assembled using hollow graphitized carbon nanofibers (GNFs) combined with nanocatalysts (Pd or Pt) and magnetic nanoparticles. The latter are introduced in the form of carbon‐coated cobalt nanomagnets (Co@Cn) adsorbed on GNF, or formed directly on GNF from ferrocene yielding carbon‐coated iron nanomagnets (Fe@Cn). High‐resolution transmission electron microscopy demonstrates that Co@Cn and Fe@Cn are attached effectively to the GNFs, and the loading of nanomagnets required for separation of the nanoreactors from the solution with an external magnetic field is determined using UV–vis spectroscopy. Magnetically functionalized GNFs combined with palladium or platinum nanoparticles result in catalytically active magnetically separable nanoreactors. Applied to the reduction of nitrobenzene the multifunctional nanoreactors demonstrate high activity and excellent durability, while their magnetic recovery enables significant improvement in the reuse of the nanocatalyst over five reaction cycles (catalyst loss < 0.5 wt%) as compared to the catalyst recovery by filtration (catalyst loss <10 wt%)

The combination of metal nanoparticles (Pd or Pt NPs) with NAD-dependent thermostable alcohol dehydrogenase (TADH) resulted in the one-flask catalytic double reduction of 3-methyl-2-cyclohexenone to 3-(1S,3S)-methylcyclohexanol. In this article some assumptions about the interactions between a chemocatalyst and a biocatalyst have been proposed. It was demonstrated that the size of the NPs was the critical parameter for the mutual inhibition: the bigger the NPs the more harmful for the enzyme they were even if the NPs themselves were only moderately inactivated. Conversely the smaller the NPs the more minimal the TADH denaturation although they were dramatically inhibited. Resuming the chemocatalysts were very sensitive to deactivation which was not related to the amount of enzyme used while the inhibition of the biocatalyst can be strongly reduced by minimizing the NPs/TADH ratio used to catalyze the reaction. Among some methods to avoid direct binding of NPs with TADH we found that using large Pd NPs and protecting their surfaces with a silica shell the overall yield of 3-(1S,3S)-methylcyclohexanol was maximized (36%)., BT/Biocatalysis

Thermal faceting of clean and oxygen-covered Pt nanocrystals was investigated at the nanoscale by means of field ion microscopy (FIM) and field emission microscopy (FEM) in the 500–700 K temperature range. FIM and FEM are used to study the morphology of the crystal prepared in the form of a sharp tip. The tip extremity is observed with nanoscale lateral resolution and corresponds to a suitable model of a single nanoparticle of a real catalyst. By contrast to similar studies on iridium, palladium and rhodium, small oxygen exposures (~ 10 L) and annealing treatments at 700 K did not lead to strong surface modifications. The field ion micrograph was similar to the pattern obtained for the nanocrystals annealed under vacuum conditions, revealing only low index {001} and {111} facets. For higher oxygen doses, i.e. ≥ 100 L, and in field-free conditions, the flat {100}, {111} and {113} facets were developed after annealing the tip at 700 K, which was attributed to the formation of oxide layers. For comparison, the surface modification was studied under oxygen-rich conditions but in the presence of an electric field at 700 K. The results showed that only former reconstruction was observed regardless of oxygen doses. These results are also promising in the frame of engineering catalysts since different gas exposure may lead to the extension or shrinking of specific facets, which may impact the efficiency of the catalyst., SCOPUS: ar.j, info:eu-repo/semantics/published

open, Catalysis has largely shaped society and will play a key part in the resolution of the energy and environment crisis we are facing in this century. The great advancements in the development of nanomaterials in the realm of nanotechnology have brought forth unforeseen possibilities also for the design of novel catalysts. The production and understanding of highly efficient catalysts based on nanostructured materials is the endeavor of the emerging field of nanocatalysis. In the last years, nanocatalysts have been studied extensively and progress in their large-scale fabrication has been demonstrated. Still, the technology is immature and further research is necessary to capitalize its full potential. Computational approaches are well suited to investigate the functioning of nanocatalysts and provide valuable atomistic insights. An accurate and efficient method is density functional theory (DFT). In this thesis, we explored the physical and chemical characteristics of supported metal clusters and oxide thin films using mainly DFT. These materials are of special interest in catalysis and many other applications, because of their unique features emerging from the nanostructuring. In particular, we investigated the geometry, the charge state, the cluster-support interaction, and the reactivity of sub-nanometer metal clusters supported on oxides. In a case study, we also addressed size-effects on larger metal nanoparticles. Regarding the supported clusters, we find that van-der-Waals dispersion forces are important for the correct description of the cluster-support interaction. Furthermore, we establish that defects and dopants present on the supporting oxide surface have a determining influence on the clusters, inherently affecting their reactivity. Also the modification of the clusters via alloying alters the metal-support interaction which can be exploited against cluster agglomeration. Nanostructuring of the oxide support engenders new material properties and in this, La catalisi ha profondamento modificato la nostra società e giocherà un ruolo chiave nella risoluzione della crisi energetica ed ambientale che stiamo affrontando in questo secolo. Il grande vantaggio nello sviluppo dei nanomateriali nel regno della nanotecnologia ha portato a possibilità impreviste anche per la progettazione di nuovi catalizzatori. La produzione e la comprensione del funzionamento di catalizzatori ad alta efficienza basati su materiali nanostrutturati è lo sforzo del campo emergente della nanocatalisi. Negli ultimi anni, i nanocatalizzatori sono stati ampiamente studiati e si è registrato un costante progresso nella loro produzione su larga scala. La tecnologia è tuttora in evoluzione ed ulteriore ricerca è necessaria per capitalizzare appieno il suo potenziale. I metodi computazionali sono molto adatti a studiare il funzionamento dei nanocatalizzatori e a fornire importanti informazioni da un punto di vista atomistico. Un accurato ed efficiente metodo è rappresentato dalla teoria del funzionale della densità (DFT). In questa tesi, abbiamo esplorato le caratteristiche chimiche e fisiche di clusters metallici supportati e di film sottili di ossidi utilizzando principalmente il metodo basato su DFT. Questi materiali sono di particolare interesse nella catalisi e in molte altre applicazioni, a causa delle loro caratteristiche uniche che derivano dalla nanostrutturazione. In particolare, abbiamo studiato la geometria, lo stato di carica, l’interazione cluster-supporto, e la reattività di clusters metallici sub-nanometrici supportati su ossidi. In un caso particolare abbiamo inoltre affrontato il ruolo della dimensione in nanoparticelle metalliche più grandi. Per quanto riguarda i clusters supportati, abbiamo verificato che le forze di dispersione di van-der-Waals sono molto importanti per la corretta descrizione dell’interazione cluster-supporto. Inoltre, abbiamo stabilito che difetti e dopanti presenti sulla superfice del supporto ossido hanno un'infl, Si, open, Schlexer, P, Schlexer, P

Nanosized Mg-doped ceria powders were obtained by self-propagating room temperature reaction without using surfactants or templates. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are solid solutions with fluorite-type structure and spherical morphology. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Mg concentration. This increasing results in a narrowing of the bandgap of CeO2. The photocatalytic performances of the Mg-doped ceria solid solutions were evaluated by decomposing an organic dye, crystal violet under UV irradiation. The Mg-doped ceria solid solutions exhibit significantly better photocatalytic activity than the pure CeO2 and commercial TiO2. The higher first rate constant of the Mg-doped samples demonstrated that they are much more efficient than TiO2 and CeO2 under UV light. Mg2+ dopant ions and oxygen vacancies play a significant role in the enhancement of photocatalytic performances of the Mg-doped ceria.

La catalisi ha profondamento modificato la nostra società e giocherà un ruolo chiave nella risoluzione della crisi energetica ed ambientale che stiamo affrontando in questo secolo. Il grande vantaggio nello sviluppo dei nanomateriali nel regno della nanotecnologia ha portato a possibilità impreviste anche per la progettazione di nuovi catalizzatori. La produzione e la comprensione del funzionamento di catalizzatori ad alta efficienza basati su materiali nanostrutturati è lo sforzo del campo emergente della nanocatalisi. Negli ultimi anni, i nanocatalizzatori sono stati ampiamente studiati e si è registrato un costante progresso nella loro produzione su larga scala. La tecnologia è tuttora in evoluzione ed ulteriore ricerca è necessaria per capitalizzare appieno il suo potenziale. I metodi computazionali sono molto adatti a studiare il funzionamento dei nanocatalizzatori e a fornire importanti informazioni da un punto di vista atomistico. Un accurato ed efficiente metodo è rappresentato dalla teoria del funzionale della densità (DFT). In questa tesi, abbiamo esplorato le caratteristiche chimiche e fisiche di clusters metallici supportati e di film sottili di ossidi utilizzando principalmente il metodo basato su DFT. Questi materiali sono di particolare interesse nella catalisi e in molte altre applicazioni, a causa delle loro caratteristiche uniche che derivano dalla nanostrutturazione. In particolare, abbiamo studiato la geometria, lo stato di carica, l’interazione cluster-supporto, e la reattività di clusters metallici sub-nanometrici supportati su ossidi. In un caso particolare abbiamo inoltre affrontato il ruolo della dimensione in nanoparticelle metalliche più grandi. Per quanto riguarda i clusters supportati, abbiamo verificato che le forze di dispersione di van-der-Waals sono molto importanti per la corretta descrizione dell’interazione cluster-supporto. Inoltre, abbiamo stabilito che difetti e dopanti presenti sulla superfice del supporto ossido ha, Catalysis has largely shaped society and will play a key part in the resolution of the energy and environment crisis we are facing in this century. The great advancements in the development of nanomaterials in the realm of nanotechnology have brought forth unforeseen possibilities also for the design of novel catalysts. The production and understanding of highly efficient catalysts based on nanostructured materials is the endeavor of the emerging field of nanocatalysis. In the last years, nanocatalysts have been studied extensively and progress in their large-scale fabrication has been demonstrated. Still, the technology is immature and further research is necessary to capitalize its full potential. Computational approaches are well suited to investigate the functioning of nanocatalysts and provide valuable atomistic insights. An accurate and efficient method is density functional theory (DFT). In this thesis, we explored the physical and chemical characteristics of supported metal clusters and oxide thin films using mainly DFT. These materials are of special interest in catalysis and many other applications, because of their unique features emerging from the nanostructuring. In particular, we investigated the geometry, the charge state, the cluster-support interaction, and the reactivity of sub-nanometer metal clusters supported on oxides. In a case study, we also addressed size-effects on larger metal nanoparticles. Regarding the supported clusters, we find that van-der-Waals dispersion forces are important for the correct description of the cluster-support interaction. Furthermore, we establish that defects and dopants present on the supporting oxide surface have a determining influence on the clusters, inherently affecting their reactivity. Also the modification of the clusters via alloying alters the metal-support interaction which can be exploited against cluster agglomeration. Nanostructuring of the oxide support engenders new material properties and in this

Nanosized Mg-doped ceria powders were obtained by self-propagating room temperature reaction without using surfactants or templates. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are solid solutions with fluorite-type structure and spherical morphology. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Mg concentration. This increasing results in a narrowing of the bandgap of CeO2. The photocatalytic performances of the Mg-doped ceria solid solutions were evaluated by decomposing an organic dye, crystal violet under UV irradiation. The Mg-doped ceria solid solutions exhibit significantly better photocatalytic activity than the pure CeO2 and commercial TiO2. The higher first rate constant of the Mg-doped samples demonstrated that they are much more efficient than TiO2 and CeO2 under UV light. Mg2+ dopant ions and oxygen vacancies play a significant role in the enhancement of photocatalytic performances of the Mg-doped ceria.

To make available atomic oxygen at the surface of a catalyst is the key step for oxidation reactions on Au-based catalysts. In this context, Au-Ag alloys catalysts exhibit promising properties for selective oxidation reactions of alcohols: low temperature activity and high selectivity. The presence of O(ads) and its effects on the catalytic reactivity is studied via the N2O dissociative adsorption and subsequent hydrogenation. Field emission techniques are particularly suited to study this reaction: Field Ion Microscopy (FIM) and Field Emission Microscopy (FEM) enable to image the extremity of sharp metallic tips, the size and morphology of which are close to those of one single catalytic particle. The reaction dynamics is studied in the 300–320 K temperature range and at a pressure of 3.5 × 10−3 Pa. The main results are a strong structure/reactivity relationship during N2O + H2 reaction over Au-8.8 at.%Ag model catalysts. Comparison of high-resolution FIM images of the clean sample and FEM images during reaction shows a sensitivity of the reaction to the local structure of the facets, independently of the used partial pressures of both N2O and H2. This suggests a localised dissociative adsorption step for N2O and H2 with the formation of a reactive interface around the {210} facets., SCOPUS: ar.j, info:eu-repo/semantics/published

Herein, the preparation of a heterogeneous catalyst consisting of 1-2nm sized Pd nanoparticles supported on amino-functionalized mesoporous hollow silica nanospheres and its use for the semihydrogenation of mono- and disubstituted alkynes is reported. By utilizing this Pd nanocatalyst together with the green poisoning agent DMSO, high yields of the desired alkenes could be achieved, while suppressing the degree of over-reduction to alkanes. To our delight, the Pd nanocatalyst displayed remarkable chemoselectivity towards the alkyne moiety, allowing the transformation to be carried out in the presence of other reducible functionalities, such as halogens, carbonyl, and nitro groups.

The development of materials science and engineering in the past decades has been closely related to the emerging challenges associated with industrial and socio-economical requirements. Catalysis research has always been in a very central position in many different industry sectors. Learning from nature, materials research community has been long understood that the isolated catalytic components are no longer sufficient to meet new technological challenges. With more strict requirements of higher conversion and higher selectivity towards specific product(s), and lower energy demands during reactions, it is often very little room for singular catalyst material to play an efficient role. Instead, considerable attention has been placed in composite catalyst research. Rich knowledge in such regard has been obtained in plenty of catalysis research disciplines, like artificial photosynthesis, electrochemical energy conversion, tandem catalysis, as well as new types of conventional nanocatalysts with tentative compositions. Still, large gap in regard of nanocomposite catalyst materials is still difficult to be filled in near future. For instance, materials selection is an open field with uncountable possibilities, opportunities as well as problems. Synergetic effect is the utmost goal while its implementation is still questionable in most systems. Tandem catalysis represents revolutionary catalytic design philosophy, but its application in real life industry reactions is rare so far. This dissertation depicts mainly the nanocomposite catalyst materials, and studies the synergetic effect between each component in different systems. It is divided into three fields. Firstly, in Part I, 2D material support in catalysis is studied and the influence of supporting material in catalytic activity and selectivity is discussed. It includes Chapter 3, in which graphene-hemin nanocomposite system was developed and explored through a simple wet synthesis route. It is applied in toluene

The development of materials science and engineering in the past decades has been closely related to the emerging challenges associated with industrial and socio-economical requirements. Catalysis research has always been in a very central position in many different industry sectors. Learning from nature, materials research community has been long understood that the isolated catalytic components are no longer sufficient to meet new technological challenges. With more strict requirements of higher conversion and higher selectivity towards specific product(s), and lower energy demands during reactions, it is often very little room for singular catalyst material to play an efficient role. Instead, considerable attention has been placed in composite catalyst research. Rich knowledge in such regard has been obtained in plenty of catalysis research disciplines, like artificial photosynthesis, electrochemical energy conversion, tandem catalysis, as well as new types of conventional nanocatalysts with tentative compositions. Still, large gap in regard of nanocomposite catalyst materials is still difficult to be filled in near future. For instance, materials selection is an open field with uncountable possibilities, opportunities as well as problems. Synergetic effect is the utmost goal while its implementation is still questionable in most systems. Tandem catalysis represents revolutionary catalytic design philosophy, but its application in real life industry reactions is rare so far. This dissertation depicts mainly the nanocomposite catalyst materials, and studies the synergetic effect between each component in different systems. It is divided into three fields. Firstly, in Part I, 2D material support in catalysis is studied and the influence of supporting material in catalytic activity and selectivity is discussed. It includes Chapter 3, in which graphene-hemin nanocomposite system was developed and explored through a simple wet synthesis route. It is applied in toluene

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Fuel Cells are important forms of sustainable power generation and Biofuel Cells utilize the use of bio-compatible/biodegradable molecules as fuels. Glucose is an ideal candidate to serve this purpose. In this project, a Glucose Fuel Cell (GFC) has been fabricated using the nanomaterials developed in the lab. The skeletal system of this GFC is a three-layered structure; a Membrane Electrode Assembly (MEA) composed of carbon electrodes (anode and cathode) and a Poly Vinyl Alcohol/Poly Acrylic Acid (PVA/PAA) polymer electrolyte. Gold and Silver (Au and Ag) nanoparticles are utilized as catalyst on the anode and cathode respectively, which are prepared by the use of green chemistry practice. One of the GFC has been compacted under hot press and the other non-hot pressed. ,which led to different surface areas. For the validation of the GFC stacks, the glucose concentration was selected around biologically available levels, i.e at 400 mg/dL in both the cases. One trial on hot pressed membrane with 200 mg/dL of glucose is also studied. Short Circuit Current (SCC) and Open Circuit Voltage (OCV) were measured following which the voltages and currents were measured across load resistances. The Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) studies were carried out on the membrane while the electrodes were characterized by Scanning Electron Microscopy (SEM). UV-Vis studies were carried out on the Au and Ag nanoparticle suspension before and after impregnation of carbon cloth electrodes. Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) has been utilized to estimate the concentration and thus the number of nanoparticles adsorbed on the surface of the carbon cloth. The variations of output current with the thickness of the membranes were studied. The assembly containing the catalytic particles showed power levels ranging between 128.7 nW-332.2 nW in the glucose concentration of 400 mg/dL. Rigorous efforts are under process to sca

Fuel Cells are important forms of sustainable power generation and Biofuel Cells utilize the use of bio-compatible/biodegradable molecules as fuels. Glucose is an ideal candidate to serve this purpose. In this project, a Glucose Fuel Cell (GFC) has been fabricated using the nanomaterials developed in the lab. The skeletal system of this GFC is a three-layered structure; a Membrane Electrode Assembly (MEA) composed of carbon electrodes (anode and cathode) and a Poly Vinyl Alcohol/Poly Acrylic Acid (PVA/PAA) polymer electrolyte. Gold and Silver (Au and Ag) nanoparticles are utilized as catalyst on the anode and cathode respectively, which are prepared by the use of green chemistry practice. One of the GFC has been compacted under hot press and the other non-hot pressed. ,which led to different surface areas. For the validation of the GFC stacks, the glucose concentration was selected around biologically available levels, i.e at 400 mg/dL in both the cases. One trial on hot pressed membrane with 200 mg/dL of glucose is also studied. Short Circuit Current (SCC) and Open Circuit Voltage (OCV) were measured following which the voltages and currents were measured across load resistances. The Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) studies were carried out on the membrane while the electrodes were characterized by Scanning Electron Microscopy (SEM). UV-Vis studies were carried out on the Au and Ag nanoparticle suspension before and after impregnation of carbon cloth electrodes. Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) has been utilized to estimate the concentration and thus the number of nanoparticles adsorbed on the surface of the carbon cloth. The variations of output current with the thickness of the membranes were studied. The assembly containing the catalytic particles showed power levels ranging between 128.7 nW-332.2 nW in the glucose concentration of 400 mg/dL. Rigorous efforts are under process to sca

[EN] Well-defined 25 nm nickel phosphide nanoparticles act as a colloidal catalyst for the chemoselective hydrogenation of terminal and internal alkynes. Cis-alkenes are obtained in mild conditions with good conversion and selectivity. The phosphorus inserted in the Ni-P nanoparticles is critical for the selectivity of the nanocatalyst. Mechanistic investigations using isotope labeling provide insight on the reactants interaction with the nanoparticles surface. They pinpoint the occurrence of C-H bond cleavage in terminal alkynes during the reaction. (C) 2012 Elsevier Ltd. All rights reserved.

[EN] Well-defined 25 nm nickel phosphide nanoparticles act as a colloidal catalyst for the chemoselective hydrogenation of terminal and internal alkynes. Cis-alkenes are obtained in mild conditions with good conversion and selectivity. The phosphorus inserted in the Ni-P nanoparticles is critical for the selectivity of the nanocatalyst. Mechanistic investigations using isotope labeling provide insight on the reactants interaction with the nanoparticles surface. They pinpoint the occurrence of C-H bond cleavage in terminal alkynes during the reaction. (C) 2012 Elsevier Ltd. All rights reserved.

A phenomenological model was developed that allows correlating the physicochemical properties of the catalyst (temperature, cluster size of the metallic phase, the dispersion of the metallic phase) with kinetic heterogeneous constants for the reactions of conversion of light hydrocarbons. The model is a mathematical relation that expresses the natural logarithm of the kinetic constant as a function of parameters characterizing the catalyst, the interaction energy of the reactant with the active site and the energy of metal-support interaction. The comparison of this theoretical expression of the kinetic constant with the Arrhenius law in logarithmic form, identified the theoretical forms of the natural logarithm of the preexponential constant (LNA) and the theoretical form of the activation energy (Ea). Subsequently the plotting of the Ea and LnA theoretical expressions generated a straight line, this result helped to show that the model developed in this paper can reproduce the compensation effect., Se desarrolló un modelo fenomenológico el cual permite correlacionar las propiedades fisicoquímicas del catalizador (temperatura, tamaño del cluster de la fase metálica, la dispersión de la fase metálica) con las constantes cinéticas heterogéneas para las reacciones de conversión de hidrocarburos livianos. El modelo es una relación matemática que expresa el logaritmo neperiano de la constante cinética como función de parámetros de caracterización del catalizador, la energía de interacción del reactante con el sitio activo y la energía de interacción metal-soporte. La comparación de esta expresión teórica de la constante cinética con la ley Arrhenius en forma logarítmica, permitió identificar las formas teóricas del logaritmo neperiano de la constante preexponencial (lnA) y la forma teórica de la energía de activación (Ea). Posteriormente la graficación de las expresiones teóricas de LnA y Ea generó una recta, este resultado permitió demostrar que el modelo desarrollado en este trabajo puede reproducir el efecto de compensación.

A phenomenological model was developed that allows correlating the physicochemical properties of the catalyst (temperature, cluster size of the metallic phase, the dispersion of the metallic phase) with kinetic heterogeneous constants for the reactions of conversion of light hydrocarbons. The model is a mathematical relation that expresses the natural logarithm of the kinetic constant as a function of parameters characterizing the catalyst, the interaction energy of the reactant with the active site and the energy of metal-support interaction. The comparison of this theoretical expression of the kinetic constant with the Arrhenius law in logarithmic form, identified the theoretical forms of the natural logarithm of the preexponential constant (LNA) and the theoretical form of the activation energy (Ea). Subsequently the plotting of the Ea and LnA theoretical expressions generated a straight line, this result helped to show that the model developed in this paper can reproduce the compensation effect., Se desarrolló un modelo fenomenológico el cual permite correlacionar las propiedades fisicoquímicas del catalizador (temperatura, tamaño del cluster de la fase metálica, la dispersión de la fase metálica) con las constantes cinéticas heterogéneas para las reacciones de conversión de hidrocarburos livianos. El modelo es una relación matemática que expresa el logaritmo neperiano de la constante cinética como función de parámetros de caracterización del catalizador, la energía de interacción del reactante con el sitio activo y la energía de interacción metal-soporte. La comparación de esta expresión teórica de la constante cinética con la ley Arrhenius en forma logarítmica, permitió identificar las formas teóricas del logaritmo neperiano de la constante preexponencial (lnA) y la forma teórica de la energía de activación (Ea). Posteriormente la graficación de las expresiones teóricas de LnA y Ea generó una recta, este resultado permitió demostrar que el modelo desarrollado en este trabajo puede reproducir el efecto de compensación.

Yin, Y., Li, W., Xu, C., Shi, L., Zhang, L. C., Ao, Z., ... Sun, H. (2020). Ultrafine copper nanoclusters and single sites for Fenton-like reactions with high atom utilities. Environmental Science: Nano, 7(9), 2595-2606. https://doi.org/10.1039/d0en00505c