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The widespread industrial use of H2O2 has provoked great interest in the development of new and more efficient materials for its detection. Enzymatic electrochemical sensors have drawn particular attention, primarily because of their excellent selectivity. However, their high cost, instability, complex immobilization, and inherent tendency toward denaturation of the enzyme significantly limit their practical usefulness. Inspired by the powerful proton-catalyzed H2O2 reduction mechanism of peroxidases, we have developed a well-defined and densely functionalized carboxylic graphene derivative (graphene acid, GA) that serves as a proton source and conductive electrode for binding and detecting H2O2. An unprecedented H2O2 sensitivity of 525 μA cm–2 mM–1 is achieved by optimizing the balance between the carboxyl group content and scaffold conductivity of GA. Importantly, the GA sensor greatly outperforms all reported carbon-based H2O2 sensors and is superior to enzymatic ones because of its simple immobilization, low cost, and uncompromised sensitivity even after continuous operation for 7 days. In addition, GA-based sensing electrodes remain highly selective in the presence of interferents such as ascorbic acid, paracetamol, and glucose, as well as complex matrices such as milk. GA-based sensors thus have considerable potential for use in practical industrial sensing technologies.

Cerium Oxide (CeO2): Synthesis, Properties and Applications provides an updated and comprehensive account of the research in the field of cerium oxide based materials. The book is divided into three main blocks that deal with its properties, synthesis and applications. Special attention is devoted to the growing number of applications of ceria based materials, including their usage in industrial and environmental catalysis and photocatalysis, energy production and storage, sensors, cosmetics, radioprotection, glass technology, pigments, stainless steel and toxicology. A brief historical introduction gives users background, and a final chapter addresses future perspectives and outlooks to stimulate future research.

Direct conversion of carbon dioxide to formic acid at thermodynamic equilibrium is an advantage of enzymatic catalysis, hardly replicated by synthetic analogs, but of high priority for carbon-neutral energy schemes. The bio-mimetic potential of totally inorganic Pd@TiO2 nanoparticles is envisioned herein in combination with Single Walled Carbon NanoHorns (SWCNHs). The high surface nano-carbon entanglement templates a wide distribution of "hard-soft" bimetallic sites where the small Pd nanoparticles (1.5 nm) are shielded within the TiO2 phase (Pd@TiO2), while being electrically wired to the electrode by the nanocarbon support. This hybrid electrocatalyst activates CO2 reduction to formic acid at near zero overpotential in the aqueous phase (onset potential at E < -0.05 V vs. RHE, pH = 7.4), while being able to evolve hydrogen via sequential formic acid dehydrogenation. The net result hints at a unique CO2 "circular catalysis" where formic acid versus H2 selectivity is addressable by flow-reactor technology. Fil: Melchionna, Michele. Università degli Studi di Trieste; Italia Fil: Bracamonte, Maria Victoria. Università degli Studi di Trieste; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina Fil: Giuliani, Angela. Università degli Studi di Trieste; Italia Fil: Nasi, Lucia. Istituto Dei Materiali Per L'elettronica Ed Il Magnetismo; Italia Fil: Montini, Tiziano. Università degli Studi di Trieste; Italia Fil: Tavagnacco, Claudio. Università degli Studi di Trieste; Italia Fil: Bonchio, Marcella. Università di Padova; Italia Fil: Fornasiero, P. Università degli Studi di Trieste; Italia Fil: Prato, Maurizio. Università degli Studi di Trieste; Italia

Appropriate and fine-tuned treatments of amorphous carbon (AC) involving aqua regia or concentrated HNO3 lead to oxidised carbon materials (oAC) which are able to catalyse 2,2′- and 3,3′-homocouplings of various functionalised indoles with outstanding activity. This newly developed carbocatalysed Cequation image[BOND]Cequation image bond formation can be achieved under mild thermal conditions. The study on the scope of the reaction revealed that the reaction can be extended to the homocoupling of other substrates of high synthetic interest such as 2-naphthol, 2-functionalised benzofurans and benzothiofurans. The characterisation of oAC with XPS together with ad hoc experiments aimed at blocking the active site revealed that the presence and distribution of C[DOUBLE BOND]O functionalities is critical and correlates well with the catalytic activity. Such experiments provide solid support for elucidation of the mechanism, suggesting a quinone nature of the active C[DOUBLE BOND]O groups, which are spontaneously regenerated by oxygen. This is confirmed by the fact that 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is able to promote the coupling in a stoichiometric fashion.

Carbon nanotubes and graphene possess a unique extended π-system that makes them stand out among carbon nanostructures. The resulting electronic properties enable electron or charge flow along one or two directions, respectively, thus offering the opportunity to connect electronically different entities that come into contact, be they living cells or catalytic systems. Using these carbon nanostructures thus holds great promise in providing innovative solutions to address key challenges in the fields of medicine and energy. Here, we discuss how chemical functionalization of these carbon nanostructures is a crucial tool to master their properties and deliver innovation.

Die Nutzung von auf festen Substraten gezogenem oder abgeschiedenem Graphen bietet wesentliche Vorteile, wenn man mithilfe von Funktionalisierungsprozessen fein abgestimmte Strukturen für die Elektronik und “intelligente” Materialien erzielen möchte. In diesem Aufsatz konzentrieren wir uns zunächst auf die Natur und die Eigenschaften von Graphen auf Substraten in Abhängigkeit von den jeweiligen Herstellungsverfahren. Anschließend analysieren wir die maßgebliche Literatur zur Funktionalisierung von Graphen auf einem Substrat. Insbesondere werden wir radikalische Reaktionen, Cycloadditionen, Halogenierungen, Hydrierungen und Oxidationen vergleichend diskutieren. Dabei werden wir besonders auf die Frage eingehen, wie die Reaktivität von Graphen durch seine Morphologie beeinflusst wird (d. h. Anzahl von Lagen, Defekte, Substrat, Krümmung usw.).

Two novel synthetic strategies to covalently link a metallocene electron-donor unit to a chlorin ring are presented. In one approach, pyropheophorbide a is readily converted into its 13(1) -ferrocenyl dehydro derivative by nucleophilic addition of the ferrocenyl anion to the 13(1) -carbonyl group. In another approach, the corresponding 13(1) -pentamethylruthenocenyl derivative is synthesised from 13(1) -fulvenylchlorin by a facile ligand exchange/deprotonation reaction with the [RuCp*(cod)Cl] (Cp*=pentamethylcyclopentadienyl; cod=1,5-cyclooctadiene) complex. The resulting metallocene-chlorins exhibit reduced aromaticity, which was unequivocally supported by ring-current calculations based on the gauge-including magnetically induced current (GIMIC) method and by calculated nucleus-independent chemical shift (NICS) values. The negative ring current in the isocyclic E ring suggests the antiaromatic character of this moiety and also clarifies the spontaneous reactivity of the complexes with oxygen. The oxidation products were isolated and their electrochemical and photophysical properties were studied. The ruthenocene derivatives turned out to be stable under light irradiation and showed photoinduced charge transfer with charge-separation lifetimes of 152-1029 ps.

In this manuscript we present a new anode catalyst, a Pd-CeO 2 /C hybrid nanostructured material composed of nanostructured Pd and nanostructured CeO 2 supported on C for direct polyalcohol fuel cells. This material fully characterized by HR-TEM, XRD, Raman spectroscopy, TGA and surface area determination techniques (BET and Chemisorption) is studied for the electrooxidation of ethylene glycol and 1,2-propanediol in electrochemical half cells and complete AEM-FCs. At a cell temperature of 60 °C peak power densities of around 50 mW cm −2 are obtained compared to 20–25 mW cm −2 for an equivalent Pd/C catalyst. For the first time the energy efficiency of such fuel cells has been determined with a value of 2% obtained for the cell fed with 1,2-propandiol. All oxidation products for each fuel have been identified and quantified using HPLC and NMR spectroscopy. From ethylene glycol 80% of glycolate is formed while from 1,2-propandiol 58% of lactate is formed. Both of these compounds are key industrial chemicals.

Summary Electrochemical oxygen reduction (ORR) is a challenging approach for the sustainable production of hydrogen peroxide (H 2 O 2 ) and is also a reaction of relevance in fuel-cell applications. Here, we propose an outstanding metal-free electrocatalyst for the unexpectedly selective ORR to H 2 O 2 , consisting of graphitized N-doped single-wall carbon nanohorns (CNHs). The catalyst can operate at acidic pH to a faradic efficiency as high as 98%, but it also shows excellent performance at either physiological or alkaline pH. Moreover, the very positive onset potentials observed at all pH values investigated (+0.40 V, +0.53 V, and +0.71 V at pH 1.0, 7.4, and 13.0, respectively), good stability, and excellent reproducibility make this material a benchmark catalyst for ORR to H 2 O 2 . The outstanding activity arises from a combination of several factors, such as CNH-dependent facilitation of electron delivery, suitable porosity, and a favorable distribution of the types of N atoms.

Self-assembling short peptides are attractive minimal systems for mimicking the constituents of living systems and building (bio)materials. The combination of both D- and L-amino acids into heterochiral sequences is a versatile strategy for building durable supramolecular architectures, especially when their homochiral analogs do not self-assemble. The reasons for this divergent behavior have remained obscure until now. Here, we elucidate how and why homochiral and heterochiral peptides behave differently. We identify a key spectroscopy signature and its corresponding molecular conformation, whereby an amphiphilic structure is uniquely enabled by the peptide stereochemistry. Importantly, we unravel the self-assembly process as a continuum from the conformation of single molecules to their organization into nano- and microstructures and through to macroscopic hydrogels, which are probed for cytotoxicity in fibroblast cell culture. In this way, (bio)material properties at the macro-scale can be linked to the chemical structure of their building blocks at the angstrom scale. Nature makes pervasive use of homochirality (e.g., D-sugars and L-peptides) to assemble biomolecules, whose interactions determine life processes. D-amino acids rarely occur, and their effects are not yet completely understood. For a long time, structural complexity (e.g., polypeptides and constrained molecules) was considered a requirement for achieving defined conformations that ultimately allow biomolecule recognition and function. Here, we detail how minimalist building blocks can adopt conformations with a characteristic spectroscopic signature, whereby substitution of just one L-amino acid for its D mirror image leads to a divergent path for assembly in water. Subtle molecular variations are amplified through increasing size scale all the way to macroscopic differences that are visible to the eye. Ultimately, the design of heterochiral (bio)molecules thus provides an alternative approach to shed new light on the supramolecular interactions that define life as we know it. This work explains why and how heterochiral and homochiral tripeptides differ in their assembly in water. A characteristic spectroscopic signature is assigned to molecular conformation. We monitor the process as a continuum from the molecular scale to the macroscopic biomaterials so that the final properties are linked to chemical structure of the building blocks. This work lays the foundation for the design of supramolecular hydrogel biomaterials based on short sequences of hydrophobic D- and L-amino acids.

Mechanically robust, chemically stable and electronically active carbon nanotubes (CNTs) are widely used as supports in catalysis. Synergistic effects between CNT and the active phase critically depend on the homogeneity of the carbon/inorganic interface, whose assembly is difficult to achieve without admixtures of free-standing inorganic matrix. Here we show that Fe-filled CNTs, employed as nanocatalyst supports, allow a facile preparation of highly pure and uniform CNT/nanocatalyst materials, by taking advantage of magnetic separation from poorly-defined components (e.g. aggregates of inorganic nanocatalysts). The higher homogeneity translates into higher catalytic activity in two industrially important processes: the photocatalytic hydrogen production and the water-gas shift reaction, WGSR (increase of ~48% activity for the former and up to ~45% for the latter as compared to catalysts isolated by standard filtration). In addition, the magnetic Fe core in the nanotubes enables effective separation and re-use of the nanocatalyst without loss of activity. This study demonstrates significant potential of magnetic CNTs as next generation of sustainable catalyst supports that can improve production of hydrogen and reduce the use of precious metals.

Catalysts are making our world more sustainable day by day. But how sustainable are catalysts themselves? In this contribution we will give a perspective overview of the progress in dematerializing catalysts, i.e., in using less (critical) materials to deliver the same (or better) level of functionality. This may be accomplished in many ways: improving the catalyst performance and durability by gaining insights in reaction, activation, and deactivation mechanisms; lowering the amount of critical or harmful catalytic components, e.g., by finding cheaper, more abundant, and sustainable substitutes; and making catalysts production and disposal processes more sustainable, e.g., by recycling. Material science and nanotechnology are two essential actors in this process, providing the tools to understand and optimize catalytic materials and processes, and to assess the environmental and toxicological impact of nanomaterials.

Carbon nanotubes have emerged as unique carbon allotropes that bear very interesting prospects in catalysis. Their use is mostly related to that of supports for inorganic metal catalysts, including molecular catalysts, metal nanoparticles, metal oxides or even more complex hierarchical hybrids. However, several reports have shown that they can intriguingly act as metal-free catalysts, with performance often superior to that of other carbon materials, in particular when ad hoc organic functional groups are attached prior to catalytic screening. The range of catalytic reactions is quite wide, and it includes standard organic synthesis, electrocatalysis, photocatalysis as well as other important industrial processes. In the last few years, the energy sector has acquired a dominant role as one of the most sought-after fields of application, given its ever-increasing importance in society.

The fourth author’s name was unfortunately misspelled on the first page and the first page of the ESM. Instead of Susy Piovesana1, Daniel Iglesias2, Manuel Melle-Franco3, Slavo Kralj4, Chiara Cavaliere1, Michele Melchionna2, Aldo Lagana1,5, Anna L. Capriotti1 (✉), and Silvia Marchesan2 (✉) It should read Susy Piovesana1, Daniel Iglesias2, Manuel Melle-Franco3, Slavko Kralj4, Chiara Cavaliere1, Michele Melchionna2, Aldo Lagana1,5, Anna L. Capriotti1 (✉), and Silvia Marchesan2 (✉)

3,6-Dihydro-2H-1,2-oxazines were synthesised via solid-phase synthesis to afford mixtures of stereo- and regioisomers. The analytical conditions for the analysis of the isomer ratio suitable for checking of reaction conditions of possible stereoselective synthesis were developed with the use of HPLC including chiral stationary phases (CSPs) based on chiral polysaccharide derivatives immobilized on a silica support. It was found that those CSPs based on an amylose backbone were more efficient than those based on cellulose for the molecules investigated. Additionally, analytical samples without complete purification could be separated under the same conditions. The asymmetric induction causing the difference in the stereoisomer ratio was observed, when an oxazine ring was built up directly on a chiral moiety. A chiral aminoacid separated from the construction site by an achiral aromatic ring did not influence the ratio of stereoisomers. The analytical conditions developed were thus verified for use in the optimisation of the regio- and stereoselective synthesis of 3,6-dihydro-2H-1,2-oxazines. The conditions are suitable for solid-phase synthesis methodology often used in high throughput synthesis of biologically active compounds.

Ceria (CeO 2 ) is enjoying increasing popularity in catalytic applications, and in some cases has established itself as an irreplaceable component. The reasons for such success stem from the intrinsic structural and redox properties of ceria. Reducing the ceria particles to the nanoscale has a profound impact on the catalytic behavior. The proliferation of improved synthetic methods that allow control over the final morphology and size of the nano-structures is opening new possibilities in terms of catalytic potential, particularly for energy-related applications.

The unique morphological characteristics of carbon nanotubes (CNTs) present the intriguing opportunity of exploiting the inner cavity for carrying out chemical reactions. Such reactions are catalysed either by the individual tubes that function both as catalysts and nanoreactors or by additional catalytic species that are confined within the channel. Such confinement creates what is called “confinement effect”, which can result in different catalytic features affecting activity, stability and selectivity. The review highlights the recent major advancements of catalysis conducted within the CNTs, starting from the synthesis of the catalytic composite, and discussing the most notable catalytic processes that have been reported in the last decade.

Carbon nanostructures (e.g., fullerenes, CNTs, graphene, nanohorns, nanodiamonds) play a key role in the development of nanomedicines. Here we analyze opportunities and barriers for their application in clinical settings. In particular, we discuss the unique properties of certain carbon nanostructures that allow for innovative solutions in theranostics, as well as current pitfalls around clinical applications of the EPR effect, the formation of the protein corona, and how functionalization of CNTs is a key tool to modulate their biodistribution and toxicity.

Sustainable energy and environmental schemes are one of the central priorities for our society, triggering a massive capital investment on research to define new trajectories for bypassing fossil fuel dependence and move to clean energy and consequent pollution abatement. The last decade has witnessed the rise and establishment of nanomaterials as front runners for a real societal impact of key processes under investigation, such as sustainable hydrogen production and CO2 conversion to fuels. The enormous progresses have been made possible by the opportunity to better understand materials at the nanoscale through the use of more powerful characterization techniques and advanced synthetic strategies. The lesson learned is that appropriately engineered multicomponent nanomaterials may hold the key to the routine industrial establishment of new greener concepts of energy production, with strong repercussions to the quality of life.

Catalysis is a pillar of green chemistry and a crucial technology in achieving sustainability and reducing environmental concerns while still maintaining a high standard of living. Better catalytic materials, showing improved activity, selectivity, and stability, are at the core of future sustainable processes at the nexus of food, water, and energy. Fundamental understanding of catalyst operation is key for the preparation of improved heterogeneous systems for several catalytic applications. In order to develop fundamental knowledge about catalytic processes that would allow us to better design and tune catalytic materials, well-defined catalytic structures are important. Materials with well-defined morphologies can indeed facilitate and accelerate the discovery and description of active sites, which is the first, crucial step in better understanding catalytic systems. Once the active sites are known, it is then possible to build materials where the density of active sites is maximized, leading to improved systems with appropriate morphologies for best catalytic results. In this chapter, we will provide the fundamental basis and rationale for the development of controlled nanostructures in heterogeneous catalysis. We will briefly summarize synthetic procedures to achieve high control over catalytic nanostructures and illustrate important cases where this control resulted crucial for the final catalytic application. This material will lead us to a discussion of the opportunities and challenges in the field, with a positive look into the future of the catalysis field where controlled nanomaterials will play an increasingly important role.

SO2 poisoning of methane oxidation over alumina-supported, Pd@CexZr1−xO2 nanoparticle catalysts was systematically studied by means of advanced PhotoElectron Spectroscopy (PES) methods. The Pd@CexZr1−xO2 units were synthesized and deposited on two modified-alumina supports, i.e. high surface area modified alumina and a model alumina prepared by Atomic Layer Deposition (ALD) of alumina on Indium Tin Oxide (ITO)/quartz slides. The model support was designed to be suitable for PES analysis and was stable to high temperature treatments (850 °C). Characterization of the high-surface-area (HSA) catalysts by X-Ray Diffraction (XRD), N2 physisorption, CO chemisorption and Transmission Electron Microscopy (TEM) indicated formation of CeO2–ZrO2 (CZ) mixed-oxide crystallites that stabilize the Pd active phase against sintering. Correlation of methane-oxidation rates with PES results demonstrated two distinct mechanisms for deactivation by SO2. Below 450 °C, the presence of SO2 in the feed led to partial reduction of the active PdO phase and to the formation of sulfates on the Pd. Above 500 °C, poisoning by SO2 was less severe due to spillover of the sulfates onto the oxide promoter. Pd@ZrO2 catalysts showed the best resistance to SO2 poisoning, outperforming analogous Pd@CZ mixed-oxide catalysts, because there was less sulfate formation and the sulfates that did form could be removed during regeneration. The authors acknowledge CERIC-ERIC for open access to instrumentation and user support. This paper was also made possible by a NPRP Grant #6-290-1-059 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. Scopus

Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Appropriate treatment of amorphous carbon with aqua regia or concentrated nitric acid leads to oxidized carbon material which is able to catalyze homocoupling reactions of benzo-fused heterocycles as well as β-naphthol.

The use of carbon nanomaterials as supports for molecular and nanostructured catalysts is becoming a more and more popular strategy to improve heterogeneous catalysis. Their outstanding electronic and optical properties together with high surface area and thermal and mechanical stabilities make them ideal elements to provide catalysts with additional or improved characteristics. The role of the carbon nanostructures in the different types of catalysis is more intricate and often involves active and strong interactions between the support and the catalytic active species, creating a synergistic effect that in many cases leads to performance enhancement and an expanded range of possible applications. In particular, photocatalysis and electrocatalysis seem to benefit from the features of these types of carbon support, although applicability can be extended to more classic transformations of organic substrates.

Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40(th) anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are deepening our understanding of these materials, helping us to predict their behavior and application potential. This review has a wide view on all those aspects related to ceria which promise to produce an important impact on our life, encompassing fundamental knowledge of CeO2 and its properties, characterization toolbox, emerging features, theoretical studies, and all the catalytic applications, organized by their degree of establishment on the market.

Considering the depletion of fossil-fuel reserves and their negative environmental impact, new energy schemes must point towards alternative ecological processes. Efficient hydrogen evolution from water is one promising route towards a renewable energy economy and sustainable development. Here we show a tridimensional electrocatalytic interface, featuring a hierarchical, co-axial arrangement of a palladium/titanium dioxide layer on functionalized multi-walled carbon nanotubes. The resulting morphology leads to a merging of the conductive nanocarbon core with the active inorganic phase. A mechanistic synergy is envisioned by a cascade of catalytic events promoting water dissociation, hydride formation and hydrogen evolution. The nanohybrid exhibits a performance exceeding that of state-of-the-art electrocatalysts (turnover frequency of 15000 H2 per hour at 50 mV overpotential). The Tafel slope of ∼130 mV per decade points to a rate-determining step comprised of water dissociation and formation of hydride. Comparative activities of the isolated components or their physical mixtures demonstrate that the good performance evolves from the synergistic hierarchical structure., Hydrogen evolution by water electrolysis is a promising route to 'green energy', but efficiency is still an issue. Here, the authors make mixed organic/inorganic hierarchical nanostructures with high hydrogen evolution activity, identifying synergic effects in the material contributing to enhanced efficiency.

Hydrogen evolution is among the most investigated catalytic processes given the importance of H2 from an industrial and an energy perspective. Achieving H2 production through green routes, such as water splitting or more realistically photoreforming of alcohols, is particularly desirable. In this work, we achieve a remarkable H2 productivity through photoreforming of either ethanol or glycerol as a sacrificial electron donor by employing a hybrid nanocatalyst where the properties of multi-walled carbon nanotubes (MWCNTs), Pd nanoparticles and crystalline TiO2 are optimally merged through appropriate engineering of the three components and an optimised synthetic protocol. Catalysts were very active both under UV (highest activity 25 mmol g−1 h−1) and simulated solar light (1.5 mmol h−1 g−1), as well as very stable. Critical to such high performance is the intimate contact of the three phases, each fulfilling a specific task synergistically with the other components.

Novel heteroarchitectures made of graphitic carbon nitride (g-C3N4) and halloysite nanotubes (HNTs) were prepared by a facile and soft self-assembly strategy. The morphological, structural and electronic properties of the HNTs/g-C3N4 nanocomposites were determined by means of a plethora of techniques including N-2 physisorption, XRD, FT-IR, TEM, UV-Vis absorption, XPS, zeta potential and photoluminescence (PL). Their photocatalytic activity was evaluated under both simulated solar light and pure visible light irradiation against the photodegradation of neutral, positively and negatively charged pollutants, namely phenol, methylene blue (MB) and methyl orange (MO), respectively. The prepared HNTs/g-C3N4 nanocomposites were proven to be durable and significantly more efficient than the pure g-C3N4 reference for the degradation of positively charged and neutral organics. The nanocomposites presented increased charge carrier formation and reduced recombination rates due to the tight contact between the two components. The enhanced photoactivity was attributed to the dual function of HNTs enhancing (a) the abundance and stability of the photogenerated e(-) and h(+) pairs and (b) the adsorption of positively charged organics on the nanocomposite. Both functions originate from the charged surface of HNTs.

Production of molecular hydrogen (H-2) is becoming an increasingly prominent process, due to high expectations as a new green energy carrier and key reagent for many industrial processes. Herein we report the high efficiency of H-2 production via photoreforming of ethanol using a catalyst based on hierarchical carbon nanocones hybridised with an inorganic layer of nanocrystalline TiO2 containing Pd nanoparticles.

Carbon nanotubes have emerged as unique carbon allotropes that bear very interesting prospects in catalysis. Their use is mostly related to that of supports for inorganic metal catalysts, including molecular catalysts, metal nanoparticles, metal oxides or even more complex hierarchical hybrids. However, several reports have shown that they can intriguingly act as metal-free catalysts, with performance often superior to that of other carbon materials, in particular when ad hoc organic functional groups are attached prior to catalytic screening. The range of catalytic reactions is quite wide, and it includes standard organic synthesis, electrocatalysis, photocatalysis as well as other important industrial processes. In the last few years, the energy sector has acquired a dominant role as one of the most sought-after fields of application, given its ever-increasing importance in society.

A synthetic approach for asymmetric ring-fused cyclopentadienes with a chiral carbon at the ring junction is established from chiral enynamines by achiral Au(III) catalysis.

The utilization of grown or deposited graphene on solid substrates offers key benefits for functionalization processes, but especially to attain structures with a high level of control for electronics and "smart" materials. In this review, we will initially focus on the nature and properties of graphene on substrates, based on the method of preparation. We will then analyze the most relevant literature on the functionalization of graphene on substrates. In particular, we will comparatively discuss radical reactions, cycloadditions, halogenations, hydrogenations, and oxidations. We will especially address the question of how the reactivity of graphene is affected by its morphology (i.e., number of layers, defects, substrate, curvature, etc.).

The development of new electrocatalysts for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) at physiological pH is critical for several fields, including fuel cells and biological applications. Herein, the assembly of an electrode based on carboxyl-functionalised hydrophilic multiwalled carbon nanotubes (MWCNTs) filled with Fe phases and their excellent performance as electrocatalysts for ORR and HER at physiological pH are reported. The encapsulated Fe dramatically enhances the catalytic activity, and the graphitic shells play a double role of efficiently mediating the electron transfer to O2 and H2O reactants and providing a cocoon that prevents uncontrolled Fe oxidation or leaching.

An efficient method is presented for preparing hierarchical catalysts composed of multi-walled carbon nanotubes (MWCNTs) and Pd@CeO2 core–shell nanoparticles. These materials were then examined for the water gas shift reaction (WGSR), which demonstrated intimate contact between the constituent parts. The integration of the carbonaceous support improves the stability of the nanoparticles by ordering the dispersion of the inorganic phase and increases the activity by suppressing the deactivation of the active phase that is commonly observed in conventional Pd–CeO2 under reducing conditions, e.g. WGSR conditions. An optimum MWCNTs:Pd@CeO2 ratio exists that affords totally homogeneous structures and provides the best catalytic properties.

A synthetic approach for asymmetric ring-fused cyclopentadienes (Cps) with a chiral carbon at the ring junction has been established from chiral enynamines by achiral Au(III) catalysis. On the basis of experimental and theoretical data, the proposed mechanistic pathway from enynamines to Cps occurs via a Au(III) ene cis–trans isomerization step. Computational studies at DFT and NEVPT2 levels advocate that the cis–trans isomerization step proceeds via a dual Au(III) push–pull assisted intermediate with a low computed rotation barrier. The chirality transfer occurs through a helical-shaped transition state with allenic character. The scope of the catalysis encompasses sterically bulky enynamines including terpene natural products.

The cycloisomerization of 2-alkynyl substituted anilines (I) is studied using a heterogeneous gold on carbon catalysts.

Covalent functionalization of carbon nanotubes (CNTs) is the attachment of chemical moieties to the CNT tubular structure via the formation of covalent bonds, which share at least one pair of electrons between the CNT and the introduced chemical moiety. The typical scope of covalent sidewall functionalization is to increase not only the dispersibility and processability of CNTs but often also their reactivity. As a result, CNT physicochemical properties can be fine-tuned for intended applications, thus opening the way to the assembly of functional advanced materials, including nanotube-based composites or hybrids.

The use of carbon nanomaterials as supports for molecular and nanostructured catalysts is becoming a more and more popular strategy to improve heterogeneous catalysis. Their outstanding electronic and optical properties together with high surface area and thermal and mechanical stabilities make them ideal elements to provide catalysts with additional or improved characteristics. The role of the carbon nanostructures in the different types of catalysis is more intricate and often involves active and strong interactions between the support and the catalytic active species, creating a synergistic effect that in many cases leads to performance enhancement and an expanded range of possible applications. In particular, photocatalysis and electrocatalysis seem to benefit from the features of these types of carbon support, although applicability can be extended to more classic transformations of organic substrates.

The rise of carbon nanotubes (CNTs) in the development of new functional materials for the most diverse applications seems to be tightly cuffed to their chemical functionalization. The reasons are multifaceted as functionalization can 1) improve solubility of CNTs, 2) provide them with anchor points for post-modification with application-dependant functional molecules 3) decrease their toxicity for medicinal and biological applications.

However, the reductive nature of those conditions limited thereaction scope and precluded the possibility of furthercascade functionalization. Soon after, Somorjai, Toste, andco-workers reported that Pt nanoparticles supported onmesoporous silica are able to efficiently promote the intra-molecular heterocyclization of N-carbamate protected 2-alkynylanilinestoaffordthecorrespondingindoleproductsinexcellent yields.

Golden ring: A route for the direct AuCl3-catalyzed conversion of an enyne–amine into cyclopentadiene is reported. The mechanism for the catalysis is proposed and supported by a resting-state zwitterionic gold(III)-cyclopentadiene structure (see figure).

The 6-aminofulvene-2-aldiminate (AFA) ligand contains both cyclopentadienyl and diimine donors. The ligand preferentially coordinates to transition metals via the nitrogen atoms; however once these are occupied, the cyclopentadienyl ring may be coordinated to a Cp*Ru+ unit, providing bi- and trimetallic species. In the tetrahedral [Zn(Ph2AFA)2] (2) the metal is located approximately in the planes of the two ligands; however in the square-planar [Pd(Ph2AFA)2] (1) there is a severe distortion of the coordination and the metal is located almost 1.3 Å out of the planes of the two ligands. This situation arises to avoid the steric interaction of the ligand phenyl substituents. Treatment of 2 with [Cp*Ru(NCMe)3][BF4] gives [Cp*Ru(η5-Ph2AFA)] (3), providing the first example of the cyclopentadienyl coordination of an AFA ligand in which the nitrogen donors are vacant, and it is thought to form as a result of the fragmentation of an intermediate mixed Zn/Ru species. The X-ray structure of 3 provides some evidence for an interaction between the Ru center and one of the exocyclic carbon atoms, thus suggesting a fulvene form of the ligand in this complex. Similar treatment of 1 with [Cp*Ru(NCMe)3][BF4] provides a trimetallic PdRu2 species (4) in which both of the cyclopentadienyl rings in the complex 2 are coordinated to Ru. The complex [(Ph2AFA)Pd(Me)PPh3] (5) is formed on treatment of [(COD)PdMe(Cl)] with NaPh2AFA in the presence of PPh3, and preliminary investigations have shown that its activation with [Ni(COD)2] as a phosphine scavenger provides species active toward ethylene oligomerization and polymerization.

Short peptide hydrogels are attractive biomaterials but typically suffer from limited mechanical properties. Inclusion of other nanomaterials can serve the dual purpose of hydrogel reinforcement and of conferring additional physicochemical properties (e.g., self-healing, conductivity), as long as they do not hamper peptide self-assembly. In particular, nanocarbons are ideal candidates, and their physicochemical properties have demonstrated great potential in nanocarbon-polymer gel biomaterials for tissue engineering or drug delivery. Recently, increasing interest in supramolecular hydrogels drove research also on their enhancement with nanocarbons. However, little is known on the effect of nanocarbon morphology on the self-assembly of short peptides, which are among the most popular hydrogel building blocks. In this work, three different oxidized nanocarbons (i.e., carbon nanotube or CNT as 1D material, graphene oxide sheet or GO as 2D material, and carbon nanohorn or CNH as 3D material) were evaluated for their effects on the self-assembly of the unprotected tripeptide Leu-DPhe-DPhe at physiological conditions. Supramolecular hydrogels were obtained in all cases, and viscoelastic properties were clearly affected by the nanocarbons, which increased stiffness and resistance to applied stress. Notably, self-healing behavior was observed only in the case of CNTs. Tripeptide–nanotube interaction was noted already in solution prior to self-assembly, with the tripeptide acting as a dispersing agent in phosphate buffer. Experimental and in silico investigation of the interaction between peptide and CNTs suggests that the latter acts as nucleation templates for self-assembly and reassembly. Overall, we provide useful insights for the future design of composite biomaterials with acquired properties.