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PTDC/NAN-MAT/30565/2017 D01-284/2019 (INFRAMAT) IBB BASE 2020-2023 UID/FIS/00068/2019. The ability to change the secondary electron emission properties of nitrogen-doped graphene (N-graphene) has been demonstrated. To this end, a novel microwave plasma-enabled scalable route for continuous and controllable fabrication of free-standing N-graphene sheets was developed. High-quality N-graphene with prescribed structural qualities was produced at a rate of 0.5 mg/min by tailoring the high energy density plasma environment. Up to 8% of nitrogen doping levels were achieved while keeping the oxygen content at residual amounts ( 1%). The synthesis is accomplished via a single step, at atmospheric conditions, using ethanol/methane and ammonia/methylamine as carbon and nitrogen precursors. The type and level of doping is affected by the position where the N-precursor is injected in the plasma environment and by the type of precursors used. Importantly, N atoms incorporated predominantly in pyridinic/pyrrolic functional groups alter the performance of the collective electronic oscillations, i.e. plasmons, of graphene. For the first time it has been demonstrated that the synergistic effect between the electronic structure changes and the reduction of graphene $-plasmons caused by N doping, along with the peculiar “crumpled” morphology, leads to sub-unitary (textless 1) secondary electron yields. N-graphene can be considered as a prospective low secondary electron emission and plasmonic material. publishersversion published

Femtosecond (fs) laser micromachining on polymeric materials is a single-step, and contactless manufacturing technology. Knowing the potential of poly(ionic liquid)s (PILs) and their derived composite materials incorporating ionic liquids (PIL–IL) to design membranes with improved CO2 separation, we here explore for the first time the creation of microchannels on the surface of PIL–IL materials by laser ablation using femtosecond laser radiation. PIL–IL membranes composed of pyrrolidinium-based PILs containing the [NTf2]– and [C(CN)3]– anions and different amounts of their corresponding ILs (40 and 60 wt%) were prepared and micromachined using fs laser pulses varying the pulse repetition rate, scanning speed, and pulse energy. The morphology of the fs laser modified PIL–IL samples was investigated through scanning electron microscopy (SEM), while the influence of the fs laser processing on the membranes structure was analyzed by solid-state nuclear magnetic resonance (ssNMR), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The CO2/N2 and CO2/H2 separation performances of the irradiated membranes were also evaluated and compared to those of the non-irradiated. Depending on the parameters used, fs laser processing was successful in modifying the surface of PIL–IL membranes through the formation of microchannels around 55–60 μm deep. Significant improvements in CO2, N2 and H2 permeabilities were achieved for the irradiated PIL–IL membranes, maintaining their CO2/N2 and CO2/H2 permselectivities.

Loosening of orthodontic and orthopedic implants is a critical and common clinical problem. To minimize the numbers of revision surgeries due to peri-implant inflammation or insufficient osseointegration, developments of new implant manufacturing strategies are indicated. Ultrafast laser surface texturing is a promising contact-free technology to modify the physicochemical properties of surfaces toward an anti-infectious functionalization. This work aims to texture Ti6Al4V surfaces with ultraviolet (UV) and green (GR) radiation for the manufacturing of laser-induced periodic surface structures (LIPSS). The assessment of these surface modifications addresses key aspects of topography, morphology and chemical composition. Human primary mesenchymal stromal cells (hMSCs) were cultured on laser-textured and polished Ti6Al4V to characterize the surfaces in terms of their in vitro biocompatibility, cytotoxicity, and metal release. The outcomes of the in vitro experiment show the successful culture of hMSCs on textured Ti6Al4V surfaces developed within this work. Cells cultured on LIPSS surfaces were not compromised in terms of their viability if compared to polished surfaces. Yet, the hMSC culture on UV-LIPSS show significantly lower lactate dehydrogenase and titanium release into the supernatant compared to polished. Thus, the presented surface modification can be a promising approach for future applications in orthodontics and orthopedics.

An experimental and theoretical investigation on microwave plasma-based synthesis of free-standing N-graphene, i.e., nitrogen-doped graphene, was further extended using ethanol and nitrogen gas as precursors. The in situ assembly of N-graphene is a single-step method, based on the introduction of N-containing precursor together with carbon precursor in the reactive microwave plasma environment at atmospheric pressure conditions. A previously developed theoretical model was updated to account for the new reactor geometry and the nitrogen precursor employed. The theoretical predictions of the model are in good agreement with all experimental data and assist in deeper understanding of the complicated physical and chemical process in microwave plasma. Optical Emission Spectroscopy was used to detect the emission of plasma-generated &lsquo, &lsquo, building units&rsquo, &rsquo, and to determine the gas temperature. The outlet gas was analyzed by Fourier-Transform Infrared Spectroscopy to detect the generated gaseous by-products. The synthesized N-graphene was characterized by Scanning Electron Microscopy, Raman, and X-ray photoelectron spectroscopies.

Iron-containing particulate catalysts of 0.1&ndash, 1 &micro, m size were prepared by wet and ball-milling procedures from common salts and characterized by FTIR, TGA, UV-Vis, PXRD, FEG-SEM, and XPS analyses. It was found that when the wet method was used, semi-spherical magnetic nanoparticles were formed, whereas the mechanochemical method resulted in the formation of nonmagnetic microscale needles and rectangles. Catalytic activity of the prepared materials in the oxidation of 1-phenylethanol to acetophenone was assessed under conventional heating, microwave (MW) irradiation, ultrasound (US), and oscillating magnetic field of high frequency (induction heating). In general, the catalysts obtained by wet methods exhibit lower activities, whereas the materials prepared by ball milling afford better acetophenone yields (up to 83%). A significant increase in yield (up to 4 times) was observed under the induction heating if compared to conventional heating. The study demonstrated that MW, US irradiations, and induction heating may have great potential as alternative ways to activate the catalytic system for alcohol oxidation. The possibility of the synthesized material to be magnetically recoverable has been also verified.

Hybrid graphene-based nanostructures are considered promising materials for energy storage applications. However, the synthesis of high-quality hybrid graphene nanostructures at high yields is challenging. In the present work we propose a novel, single-step microwave plasma-enabled approach to synthetize customizable hybrid graphene-based nanostructures at high-yield while preserving their quality. Hybrid N-graphene (nitrogen-doped graphene) metal-based nanostructures, for instance, can be produced at a rate of ∼ 19 mg/min. The high energy density region of a microwave plasma provides sufficient energy and “building particles” fluxes towards the low-energy density plasma afterglow for the processes of assembly and growth of N-graphene sheets. Simultaneously, a controlled jet of metal-oxide(-sulfide) microparticles is sprayed into the plasma afterglow region where they bind to N-graphene sheets. Methane/methylamine are used as carbon and nitrogen precursors, combined with micron-sized MnO2 and oxy-MnS particles to synthesize the hybrid structures. As a result, nano-sized (∼10–30 nm) MnOx particles decorated N-graphene (4.6 at. N%) and oxidized metal sulfide anchored N-graphene sheets (3.1 at. N%) are produced at atmospheric conditions. High structural quality and distribution of metal-based nanostructures on N-graphene sheets are revealed using transmission and scanning electron microscopes and other advanced spectroscopic techniques. Finally, an electrode for supercapacitor based on the N-graphene-metal-oxide(sulfide) hybrid nanostructures is developed with promising specific capacitances (∼273 F.g−1 at 0.5 A.g−1). The described chemically engineered process is one of the fastest approaches reported for designing the high-quality hybrid nanostructures produced at a high-yield, and as such, is expected to provide a high impact on the design of electrode materials for sustainable energy storage systems.

Aiming the degradation of harmful molecules under visible light, new photocatalytic systems were created. For this purpose, the surface of chitosan thin films was modified in heterogeneous phase via a simple and straightforward mild chemical process: chemisorption of silver ions followed by the synthesis in situ of TiO2 at low temperature (100 °C). A high photocatalytic activity under visible light was observed, leading to the degradation and/or mineralization of different organic products such as o-toluidine, salicylic acid and 4-aminomethyl benzoic acid. This efficiency is partly attributed to the formation of Ag NPs and also to the unexpected appearance of AgCl NPs, likely formed from the residual chlorine contained in the chitosan. The resulting TiO2/Ag/AgCl/Chitosan system is easy to prepare under mild conditions, avoiding calcination treatments and opens new perspectives for the production of visible light-driven photocatalysts. Samples were analysed by different techniques: XRD, Raman, FE-SEM, XPS, TGA, GSDR, LIF and LIP.

Current TiO2 photocatalysts used to degrade emergent waterborne pollutants are inefficient due to the usage of UV irradiation, which is scarce in solar light, and generally fall short in reaching its microbial properties. In this study, synthesized cobalt-doped (Co-TiO2) and cobalt and nitrogen co-doped (Co-TiO2-N) anatase nano-catalysts were active in degrading triclosan (TCS), a common antimicrobial agent and prominent aquatic pollutant, under UV and visible light, as well as exhibiting antibacterial activity under UV-A light. The developed Co-TiO2-N catalyst displayed the best photocatalytic activity under UV (365 nm) and Vis (450 nm) LED lights irradiation, achieving nearly complete (> 99%) TCS degradation (10 ppm) in 20 min. The identification of some of the intermediate products was carried out by UHPLC-MS/MS, showing that the TCS is primarily mineralized. Furthermore, the antibacterial responses of both Co-TiO2-N and Co-TiO2 catalysts showed auspicious effects against a major waterborne pathogen, Legionella pneumophila, whereas cobalt doping seems to favor the antibacterial action against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. This work highlighted the potential of cobalt and nitrogen doping of TiO2 for water decontamination, as well as its usage with UV–Vis LED light sources, which is expected to promote photocatalytic research due to its lower cost and extended life span.

In recent years, with the development of micro/nanoelectromechanical systems (MEMS/NEMS), the demand for efficient lubricants of silicon surfaces intensified. Although the use of ionic liquids (ILs) as additives to base oils in the lubrication of steel/steel or other types of metal/ metal tribological pairs has been investigated, the number of studies involving Si is very low. In this work, we tested imidazolium-based ILs as additives to the base oil polyethylene glycol (PEG) to lubricate Si surfaces. The friction coefficients were measured in a nanotribometer. The viscosity of the PEG + IL mixtures as well as their contact angles on the Si surface were measured. The topography and chemical composition of the substrates surfaces were determined with atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. Due to the hygroscopic properties of PEG, the first step was to assess the effect of the presence of water. Then, a series of ILs based on the cations 1-ethyl-3-methylimidazolium [EMIM], 1-butyl-3-methylimidazolium [BMIM], 1-ethyl-3-vinylimidazolium [EVIM], 1-(2-hydroxyethyl)-3-methylimidazolium [C2OHMIM] and 1-allyl-3-methylimidazolium [AMIM] combined with the anions dicyanamide [DCA], trifluoromethanesulfonate [TfO], and ethylsulfate [EtSO4] were added to dry PEG. All additives (2 wt %) led to a decrease in friction coefficient as well as an increase in viscosity (with the exception of [AMIM][TfO]) and improved the Si wettability. The additives based on the anion [EtSO4] exhibited the most promising tribological behavior, which was attributed to the strong interaction with the Si surface ensuring the formation of a stable surface layer, which hinders the contact between the sliding surfaces.

A simplification of the overall method of producing trimethylsilylcellulose solutions in common organic volatile solvents is reported. Microcrystalline cellulose was derivatized aiming its solubilization in tetrahydrofuran and toluene to obtain ultra-thin films of cellulose by spin-coating. The main simplifications are: 1) elimination of a swelling step before dissolution in the binary solvent N,N-dimethylacetamide/LiCl by using microcrystalline cellulose; 2) derivatization of cellulose –OH groups with –Si(CH3)3 groups was successful with no additional catalyst, like trimethylsilyl chloride, the degree of substitution (DS) being 2.2 ± 0.1. The DS at the extreme surface of the films was computed from the X-ray Photoelectron Spectroscopy data: using solely C 1s fitted component areas and, alternatively, from both C 1s and Si 2p areas. The DS estimated with a technique specific of the surface is close to the bulky one obtained from gravimetric measurements reported in the literature for materials synthesized with catalyst. The topographic uniformity is shown by Atomic Force Microscopy.

Free-standing N-graphene was synthesized using a microwave plasma-based method at atmospheric pressure conditions through a single step and in a controllable manner. Using ethanol and ammonia as precursors, N-graphene with low relative amount of bonded oxygen and low level of saturated sp3 carbon bonds was produced. Adjusting the injection position of the nitrogen precursor in the plasma medium leads to selectivity in terms of doping level, nitrogen configuration and production yield. A previously developed theoretical model, based on plasma thermodynamics and chemical kinetics, was further updated to account for the presence of nitrogen precursor. The important role of HCN attachment to the graphene sheets as the main process of N-graphene formation is elucidated. The model predictions were validated by experimental results. Optical Emission Spectroscopy was used to detect the emission of plasma generated “building units” and to determine the gas temperature. The plasma outlet gas was analyzed by Fourier-Transform Infrared Spectroscopy to detect the generated gaseous by-products. The synthesized N-graphene was characterized by Scanning Electron Microscopy, Raman and X-ray photoelectron spectroscopies.

In this paper, the effect of femtosecond laser nanotexturing of surfaces of Ti6Al4V and Zr implants on their biological compatibility is presented and discussed. Highly regular and homogeneous nanostructures with sub-micrometer period were imprinted on implant surfaces. Surfaces were morphologically and chemically investigated by SEM and XPS. HDFa cell lines were used for toxicity and cell viability tests, and subcutaneous implantation was applied to characterize tissue response. HDFa proliferation and in vivo experiments evidenced the strong influence of the surface topography compared to the effect of the surface elemental composition (metal or alloy). The effect of protein adsorption from blood plasma on cell proliferation is also discussed.

International audience; The functionalization of cotton fabric with photoactive TiO2-Ag-AgBr nanostructured layer has been successfullydeveloped using a lowtemperature non-aqueous sol-gel route and aqueous suspension of AgBr. Evidence for thegrowth of TiO2 layer and the immobilization of AgBr nanoparticles have been confirmed by Raman, XRD and XPS.GSDR analysis revealed a strong absorption in the visible region brought by surface Plasmon resonance (SPR) ofAg nanocrystals generated at the surface of AgBr. The XPS evidenced the presence of Ag+, Ag0 and bromine, suggestingthat Ag0 formed a shell around the deposited AgBr. The immobilized TiO2-Ag-AgBr heterostructured layerimparts a strong photocatalytic activity under visible light for the degradation of dyes in aqueous solution aswellas of dimethyl methylphosphonate (DMMP), a chemical warfare agent simulant.These new catalytically active functionalized fabrics, with self-detoxification properties, have great potential forapplication in chemical protective clothes and might offer new opportunities for the design of functional materialsfor toxic chemical protection.

This work investigates the influence of the type of buffer electrolyte used in the generation of Electrochemical Hydrophilic Carbon (EHC) on their physical-chemical properties and electrocatalytic activity. The EHC nanomaterials were prepared in three different biological buffers, phosphate, glycine and citrate buffers (EHC@phosphate, EHC@glycine, EHC@citrate) and their surface properties were fully characterized by AFM, XPS and Raman. The EHC nanomaterials drop cast onto a glassy carbon electrode were electrochemically characterized in [Fe(CN)6]3-/4- and [Ru(NH3)6]3+/2+ redox probes solutions, and their electrocatalytic activity was investigated towards hydrogen peroxide and oxygen reduction reactions (ORR) in a phosphate buffer solution. It was found that the nature of buffer electrolyte strongly influences the surface chemical state of the EHC materials, disorder degree in the hexagonal sp2 carbon network and oxygen functional groups, affecting both the EHC electrocatalytic activity towards the ORR and H2O2 reduction reaction. The most catalytic material for the ORR was EHC@citrate, whereas EHC@glycine showed the highest oxygen conversion (n ≅ 2.7 to 3). Moreover, it was shown that the content of oxygen singly bonded to carbon correlates strongly with the number of electrons transferred. A very singular behaviour in the electrochemical reduction of hydrogen peroxide was observed on EHC@glycine, qualitatively interpreted as an autocatalytic reaction. In contrast, a blocking-like effect was depicted on EHC@phosphate. These results must have an important impact in the development of materials with peroxidase-like activity and in the design of O2 sensors with non-sensitivity to H2O2.

Intensification of chemical processes according to the motto “faster, simpler, greener” is among the main concerns nowadays. One of the ways of intensification is the application of synergistic catalytic effects when the overall efficiency of a composite catalyst is much higher than the sum of the component activities. Here, we report on the preparation of synergistic catalytic materials by a simple and straightforward ball milling procedure. Oxidation of benzoin was selected as a model reaction to demonstrate the viability of the concept. For the V2O5–TiO2 (95 : 5) composite material, the synergistic effect is triggered by low power microwave irradiation with more than a tenfold jump in the catalytic activity in comparison to the activities of the individual components.

Reproducible materials that have detection properties towards a certain molecule are very important for applications in the fabrication of devices. Among all the substrates that are used, highly oriented pyrolytic graphite allows to clearly image a monolayer. On the other hand, cryptand molecules are versatile because they can sense certain analytes with high selectivity. The highly oriented pyrolytic graphite electrode was first functionalized with an aryl bearing a bromine or an alkyne group to further attach cryptand molecules to its surface. The functionalization was performed through the electroreduction of aryl diazonium salts. While functionalization with an aryl-bromine produced a 20 nm-thick dendritic layer, functionalization of the surface with an aryl bearing a terminal alkyne produced a 9.7 nm-thick multilayer. However, if the diazonium salt is prepared in situ, a 0.9 nm monolayer with aryl–alkyne groups is formed. The alkyne functionalized electrode reacted with a bromo-cryptand through a Sonogashira C–C coupling reaction yielding electrodes functionalized with cryptands. These were immersed in a solution of a Co(II) salt resulting in Co(II)-cryptate modified electrodes, highlighting the ability of the cryptands’ modified electrode to sense metal ions. The electrode surface was analyzed by X-ray photoelectron spectroscopy after each modification step, which confirmed the successful functionalization of the substrate with both the cryptand and the cryptate. Cyclic voltammetry studies showed stable current response after approximately six cycles. Different reduction processes were detected for both cryptand (−1.40 V vs. SCE) and cryptate (−1.22 V vs. SCE) modified highly oriented pyrolytic graphite.

Resistive switching in metal–insulator–metal nanosctructures is being intensively studied for nonvolatile memory applications. Here, we report unipolar resistive switching in Pt/MgO/Ta/Ru structures, with a 30 nm oxide barrier. A forming process was needed to initiate the resistive switching, which was then observed for all Set and Reset voltage polarity combinations. We studied the influence of the voltage polarity on the variability of the Set/Reset voltages and ON/OFF resistances and revealed the importance of a thin TaOx layer working as an oxygen revervoir for resistive switching. The mechanism behind this phenomenon can be understood in terms of conductive filaments formation/rupture with a contribution from Joule heating. Resistance change is thus caused by a voltage-driven oxygen vacancy motion in the MgO layer and a filament model was proposed for each polarity mode. A OFF/ON resistance ratio of at least 2 orders of magnitude was obtained with resistive states stable up to 104 s. Our results open the prospect to improve switching performance in other resistive switching systems, by proving a better understanding of the differences between operation modes.

We report on significant efficiency enhancement of bulk heterojunction organic photovoltaic cells based on blends of poly(9,9-dioctylfluorene-alt-bithiophene), F8T2, or poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl], PTB7, with [6,6]-phenyl-C61-butyric acid methyl ester, PC61BM, upon thermally depositing a layer of a phenanthroline derivative, 4,7-diphenyl-1,10-phenanthroline, BPhen, or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, BCP, and LiF. We found that both phenanthroline derivatives form nanostructured layers and that the introduction of the LiF layer is crucial for the cells performance improvement. The interface between BPhen and LiF was investigated by X-ray photoelectron spectroscopy (XPS). This analysis suggested that charge-transfer doping of BPhen by fluoride is at the origin of improved electron transport throughout the BPhen layer. The best performing cells display power conversion efficiencies of 2.89 % and 5.89 %, for the blend with F8T2 and PTB7, respectively.

Hybrid chitosan-TiO 2 photocatalysts were prepared by means of in situ generation of TiO 2 through a non-hydrolytic sol–gel process, using tetrabutyl titanate, as a precursor, tert-butanol as solvent, and chitosan as a template. TiO 2 nanoparticles in the anatase and amorphous forms, with sizes ranging from 5 to 15 nm were generated according to the heating temperature. Evidence of the microstructure evolution of the generated TiO 2 nanoparticles were provided by XRD, Raman, XPS and UV–vis diffuse reflectance analysis. The in situ generation of TiO 2 NPs and their immobilization on the surface of the chitosan was shown to be effective in controlling the crystallization process and to limit the aggregation of the NPs during the thermal treatment. The chitosan templating and the non-hydrolytic sol–gel approach has contributed to lower the onset crystallization temperature of anatase TiO 2 to about 150 °C. The hybrid chitosan-TiO 2 nanomaterials showed good photocatalytic activity under visible-light illumination.

To get a better insight on the transport mechanism of peptide-conjugated nanoparticles to tumors, we performed in vivo biological studies of bombesin (BBN) peptide functionalized gold nanoparticles (AuNPs) in human prostate tumor bearing mice. Initially, we sought to compare AuNPs with thiol derivatives of acyclic and macrocyclic chelators of DTPA and DOTA types. The DTPA derivatives were unable to provide a stable coordination of (67)Ga, and therefore, the functionalization with the BBN analogues was pursued for the DOTA-containing AuNPs. The DOTA-coated AuNPs were functionalized with BBN[7-14] using a unidentate cysteine group or a bidentate thioctic group to attach the peptide. AuNPs functionalized with thioctic-BBN displayed the highest in vitro cellular internalization (≈ 25%, 15 min) in gastrin releasing peptide (GRP) receptor expressing cancer cells. However, these results fail to translate to in vivo tumor uptake. Biodistribution studies following intravenous (IV) and intraperitoneal (IP) administration of nanoconjugates in tumor bearing mice indicated that the presence of BBN influences to some degree the biological profile of the nanoconstructs. For IV administration, the receptor-mediated pathway appears to be outweighed by the EPR effect. By contrast, in IP administration, it is reasoned that the GRPr-mediated mechanism plays a role in pancreas uptake.

Enzyme immobilization has been the focus of extensive research over decades, yet empiricism still often prevails over rational design. To overcome this pattern and develop high performance, cost-effective systems, a trend toward a more comprehensive characterization of the heterogeneous bioconversion systems is emerging. This work encompasses such scope. The model system is the immobilization of invertase on glass substrate for the production of invert sugar syrup through sucrose hydrolysis. Before invertase immobilization, the glass substrates were cleaned and hydroxylated; next, substrate functionalization was performed by incubation with (3-aminopropyl)triethoxysilane and glutaraldehyde. Detailed characterization was performed by monitoring every step of the immobilization protocol by contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy. Enzyme loading and affinity toward the functionalized substrate was evaluated with a quartz crystal microbalance. The successful deposition of the different coating reagents and of the enzyme was confirmed by the shifts in surface wettability and roughness. XPS highlighted the over-simplistic nature of common models for chemical interaction between layers. Surface saturation was observed for the protein concentration of 0.5 mg/mL alongside with surface coverage of 910 ng enzyme /cm 2 . Finally, the suitability of the enzyme immobilization protocol was validated through operation in a packed bed reactor.

The introduction of oxygen moieties on a carbon-based material to enhance the electrode material activity for the oxygen reduction reaction (ORR) is a most unexplored experimental approach due to the risk of reducing the electron-transport ability of the electrode material. Herein, it is shown that carbon nanomaterials generated electrochemically from graphite can simultaneously show an anomalous high content of oxygen functionalities and a high heterogeneous electron transfer rate. This study was demonstrated with a set of four samples, prepared at different galvanostatic conditions. All the samples display a non-ordered carbon network dominated by aromatic rings, an O/C ratio greater than 0.4, but different amounts of various oxygen-containing functionalities. The electron-transport properties of the obtained films were appraised by cyclic voltammetry and electrochemical impedance spectroscopy. The application of these metal-free electrode materials to the ORR in the alkaline medium has shown a direct correlation between the materials catalytic activity (potential onset, kinetic current and number of electrons transferred) and the Cdouble bondO amount, whereas a negative correlation was found for Csingle bondO. Their excellent ability for the H2O2 reduction was also demonstrated. This work opens a new perspective on the use of highly oxidized carbon nanomaterials in electrocatalysis. published

A highly hydrophilic carbon nanomaterial was generated by using an electrochemical approach, and its structure, chemical composition, redox properties, antioxidant activity and effects on cells were characterised. It was found that the nanomaterial possesses a structure dominated by sp2 carbon atoms in a non-ordered carbon network formed by small clusters (

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/MechSynCat_ISEL The effect of microwave and mechanochemical ball milling energy inputs was studied for the peroxidative oxidation (with aqueous H2O2) of cyclohexane to cyclohexanol and cyclohexanone, over CoCl2 and/or V2O5 dispersed (μm scale) catalysts. A maximum total yield of cyclohexanol and cyclohexanone of 43% after 1 h of reaction at 30 °C, in acetonitrile and under microwave irradiation (5 W), was achieved over the CoCl2–V2O5 (3 : 1) catalyst prepared by ball milling. Cyclohexanol is the main final product with a selectivity of up to 93% over cyclohexanone. Conducting the oxidation reaction under microwave irradiation under the same conditions but without any mechanochemical treatment of the catalyst prior to use resulted in a lower total yield of 30% with a lower selectivity (69%) towards cyclohexanol over cyclohexanone. The sole application of mechanochemical treatment for the catalyst preparation and the catalytic oxidation of cyclohexane allowed to reach yields of 29% after 1 h of reaction, at room temperature, without microwave irradiation and any additive and in the absence of any organic solvent. Ball milling is shown to provide a convenient, solvent-free method to disperse these solid catalysts and to promote the above cyclohexane oxidation, although, in the latter case, not so effectively as microwave irradiation. info:eu-repo/semantics/publishedVersion

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/MechSynCat/ISEL Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4 with polyphenols from tea extracts, which act as both reducing and capping agents. The obtained AuNPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), and X-ray photoelectron spectroscopy (XPS). They act as highly efficient catalysts in the reduction of various aromatic nitro compounds in aqueous solution. The effects of a variety of factors (e.g., reaction time, type and amount of reducing agent, shape, size, or amount of AuNPs) were studied towards the optimization of the processes. The total polyphenol content (TPC) was determined before and after the catalytic reaction and the results are discussed in terms of the tea extract percentage, the size of the AuNPs, and their catalytic activity. The reusability of the AuNP catalyst in the reduction of 4-nitrophenol was also tested. The reactions follow pseudo first-order kinetics. info:eu-repo/semantics/publishedVersion

For the first time, a magnetic C-scorpionate catalyst was prepared from the iron(II) complex [FeCl2{_3-HC(pz)3}] (pz = pyrazol-1-yl) and ferrite, using the sustainable mechanochemical synthetic procedure. Its catalytic activity for the cyclohexane oxidation with tert-butyl hydroperoxide (TBHP) was evaluated in different conditions, namely under microwave irradiation and under the effect of an external magnetic field. The use of such magnetic conditions significantly shifted the catalyst alcohol/ketone selectivity, thus revealing a promising, easy new protocol for tuning selectivity in important catalytic processes. info:eu-repo/semantics/publishedVersion

Water is one of the most valuable resources today and its purity is crucial to health and society well-being. The access to safe drinking water is decreasing in the world, which can have a huge socio-economic impact especially in developing countries, more prone to water-associated diseases. The goal of this work was to develop an innovative, fast, and cost-effective 3D material capable of decontaminating water. We have used an eco-friendly strategy, combining plasma surface activation and supercritical fluid technology to produce, for the first time, a 2-oxazoline-grafted 3D surface with broad-spectrum contact-active antimicrobial properties. Oligo(2-methyl-2-oxazoline) quaternized with N,N-dimethyldodecylamine and grafted to a chitosan (CHT) scaffold (CHT-OMetOx-DDA) efficiently and quickly (3 min) killed99.999% of Staphylococcus aureus and Escherichia coli cells upon direct contact and avoided bacterial adhesion to the materials surface, which is important for the prevention of biofilm formation. As a proof of concept, CHT-OMetOx-DDA scaffold was demonstrated to be suitable for water purification efficiently killing the microorganisms present in different water samples within minutes of contact and without leaching to the water. Additionally, we report for the first time a new method to clearly distinguish two mechanisms of action of bioactive surfaces: contact-active and releasing systems.

New PdP cathodes with 10 at.% P (PdP10) as catalysts for the oxygen reduction reaction (ORR) were prepared by using different electroless deposition times onto a carbon paper and compared to PdP15, Pd and Pt. The as-prepared electrodes were characterized by SEM, XRD, TEM/SAED and XPS. The electrochemical activity was evaluated using CO stripping, cyclic and linear sweep voltammetry and rotating disk electrode in acid media in the presence, and in the absence of methanol. It is shown that the PdP10 and PdP15 are mainly composed of nanocrystals aggregated as spherical nanoparticles, dispersed in an amorphous matrix. The electrochemical testing showed that hydrogen absorption and the CO tolerance of PdP10 is higher than for PdP15. ORR proceeded via the 4-electron pathway on both catalysts. PdP10 presented the highest ORR mass activity together with a high methanol tolerance. At the end of the accelerated stability test, the mass activity of PdP10 for the ORR increased by about 30%, whereas the at.% P remained the same. The improved performance was explained by atomic rearrangement, the initial spherical-type nanoparticles becoming 3D tree-like dendrites with increased particle size. The PdP10 was tested as the cathode catalyst in a single polymer electrolyte fuel cell (PEMFC), achieving a mass activity of 1.75 A mgPd−1 at 0.5 V and 60 °C, which is in the superior range of performance of PEMFCs without Pt at the cathode.

This work stresses on damage at the molecular level caused by ultraviolet radiation (UV) in the range from 3.5 to 8 eV, deoxyribonucleic acid (DNA) films observed by X-ray photoelectron spectroscopy (XPS). Detailed quantitative XPS analysis, in which all the amounts are relative to sodium-assumed not to be released from the samples, of the carbon, oxygen, and particularly, nitrogen components, reveals that irradiation leads to sugar degradation with CO-based compounds release for energies above 6.9 eV and decrease of nitrogen groups which are not involved in hydrogen bonding at energies above 4.2 eV. Also the phosphate groups are seen to decrease to energies above 4.2 eV. Analysis of XPS spectra allowed to conclude that the damage on bases peripheral nitrogen atoms are following the damage on phosphates. It suggests that very low kinetic energy photoelectrons are ejected from the DNA bases, as a result of UV light induced breaking of the phosphate ester groups which forms a transient anion with resonance formation and whereby most of the nitrogen DNA peripheral groups are removed. The degree of ionization of DNA was observed to increase with radiation energy, indicating that the ionized phosphate groups are kept unchanged. This result was interpreted by the shielding of phosphate groups caused by water molecules hydration near sodium atoms.

With the aim of improving blood compatibility of low density polyethylene (LDPE) films, an effective low-pressure plasma technology was employed to functionalize the LDPE film surfaces through in-situ grafting of acrylic acid (AAc). Subsequently, the molecules of poly(ethylene glycol) (PEG) and chitosan (CHI) were immobilized on the surface of grafted LDPE films. The unmodified and modified LDPE films were analyzed using various characterization techniques such as contact angle, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) to understand the changes in surface properties such as hydrophilicity, surface topography and chemical composition, respectively. Furthermore, LDPE films have been subjected to an ageing process to determine the durability of the plasma assisted surface modification. The blood compatibility of the surface modified LDPE films was confirmed by in vitro tests. It was found that surface modified LDPE films show better hydrophilic behavior compared with the unmodified one. FTIR and XPS results confirm the successful immobilization of CHI on the surface of LDPE films. LDPE films showed marked morphological changes after grafting of AAc, PEG and CHI which were confirmed through AFM imaging. The in vitro blood compatibility tests have clearly demonstrated that CHI immobilized LDPE films exhibit remarkable anti thrombogenic nature compared with other modified films. Surface modified LDPE films through low-pressure plasma technique could be adequate for biomedical implants such as artificial skin substrates, urethral catheters or cardiac stents, among others.

The morphology of blends made of a ferroelectric polymer, poly(vinylidene fluoride-co-trifluoroethylene), and a cross-linkable conjugated polymer, an oxetane-functionalized poly(9,9-dioctylfluorene-alt-bithiophene), is investigated. Making use of the insolubility of the conjugated polymer, we were able to selectively remove the ferroelectric copolymer and analyze the remaining material. Atomic force microscopy studies show a lateral phase separation, consistent with columns of the conjugated polymer surrounded by a matrix of the ferroelectric. X-ray photoelectron spectroscopy showed that even after a very long washing time (120 h), there was still ferroelectric polymer on the remaining film, which we conclude to correspond to ferroelectric chains trapped within the conjugated polymer domains. This fact suggests the existence of a diffuse interface between the two polymer domains. Resistive memories were fabricated with this blend, though exhibiting limited nonvolatility. This behavior is discussed in term...

Metallic silver nanoparticles were synthesized in aqueous solution using chitosan, as both reducing and stabilizing agent, and AgNO 3 as silver precursor aiming the production of solid ultra-thin films. A systematic characterization of the resulting system as a function of the initial concentrations was performed. The combination of UV–vis absorption – and its quantitative analysis – with X-ray photoelectron spectra, light scattering measurements and atomic force microscopy allowed obtaining a rational picture of silver reduction mechanism through the identification of the nature of the formed reduced/oxidized species. Nanoparticle mean sizes and sizes distributions were rather independent from the precursors initial absolute and relative concentrations ([AgNO 3 ]/[chitosan]). This work clarifies some points of the mechanism involved showing experimental evidence of the early stages of the very fast silver reduction in chitosan aqueous solutions through the spectral signature of the smallest silver aggregate (Ag 2 + ) even at room temperature. The characterized system is believed to be useful for research fields where silver nanoparticles completely exempt of harmful traces of inorganic ions, coming from additional reducing agents, are needed, especially to be used in biocompatible in films.

Zinc(II) complexes of general formula [ZnX2(YNC10H14O)], [ZnX2(YNC10H13NSO2)], [ZnX2(H2NNC10H14O)2], [{ZnX2}2(YNC10H14O)] and [{ZnX2}2(YNC10H13NSO2)] were obtained from zinc halides (chloride or bromide) by reaction with the suitable camphor ligands. In most of the complexes, the camphor ligands remain unchanged upon coordination, except in [{Zn(MeNNC10H14O)}2(μ-Cl)2] where proton loss from MeHNNC10H14O occurs. The new complexes and camphor derivatives were characterized by IR, NMR (1H, 13C{H}, DEPT, 2D) and elemental analysis. In some cases the surface composition was studied by X-ray photoelectron spectroscopy (XPS) and imaged by Scanning Electron Microscopy (SEM). Images of [ZnCl2(Me2NNC10H14O)] and [ZnCl2(Me2NNC10H13NSO2)] obtained by SEM show the solid particles have tubular structures capped in one or both extremities. The coordination of THF in [ZnCl2(YNC10H14O)THF] was confirmed by X-ray diffraction analysis. The camphor derivatives YNC10H14NSO2 (Y = NMe2; NHMe) and p-C6H4(NC10H14O)2 were structurally characterized by X-ray diffraction analysis. The ability of selected Zn(II) camphor complexes to catalyse the cyclization of 4-pentyn-1-ol was evaluated showing that the binuclear complex [{ZnX2}2(YNC10H14O)] performs better than the mononuclear Zn(II) complexes.

Monoliths represent powerful platforms for isolation of large molecules with high added value. This work presents a hybrid approach for antibody (Ab) capture and release. Using mostly natural polymers and clean processes, it is possible to create macroporous monoliths with well-defined porous networks, tuneable mechanical properties, and easy functionalization with a biomimetic ligand specific for Ab. Magnetic nanoparticles (MNPs) are embedded on the monolith network to confer a controlled magnetic response that facilitates and accelerates Ab recovery in the elution step. The hybrid monolithic systems prepared with agarose or chitosan/poly(vinyl alcohol) (PVA) blends exhibit promising binding capacities of Abs directly from cell-culture extracts (120 ± 10 mg Ab g−1 support) and controlled Ab magnetically-assisted elution yielding 95 ± 2% recovery. Moreover, a selective capture of mAbs directly from cell culture extracts is achieved yielding a final mAb preparation with 96% of purity.

Potassium-lanthanide chloride molten salts (KCl–LnCl3, Ln = La, Ce, Sm, Dy and Yb) were used as catalysts for the oxidation of methane with N2O. They proved to be active and selective for the production of C2 hydrocarbons (e.g. CH4 conversion ≈ 15% and C2 selectivity > 75% over the KCl–CeCl3 catalyst at 750 °C) and remarkably stable for long periods of time on the gaseous stream (> 48 h). It was also found that their catalytic performance depends on the f block element (increases when La is replaced by Ce, Sm or Dy). The factors that seem to contribute to the variation of the activity and selectivity are the catalysts acid–base properties (higher acidity implies high activity, but lower selectivity to C2 hydrocarbons) and the oxidative character of the rare earth trivalent ions in the potassium chloride molten melt (high oxidation-reduction potentials implies lower activity and higher selectivity to hydrocarbons). The effect of the type of oxidant was also studied. The potassium-lanthanide chloride molten salts were more selective to hydrocarbons under N2O than under O2, e.g. ≈ 75 vs. ≈ 40% over KCl–CeCl3, respectively, which is clearly an advantage taking into account that nitrous oxide is a major greenhouse agent. To our knowledge, this is the first time that molten metal chloride catalysts were used as catalysts for the catalytic conversion of methane into hydrocarbons using N2O as oxidant.

Ordered copper integrated mesoporous silicate catalysts (CuMSC) have been synthesized by the utilization of the amphiphilic tri-block copolymer pluronic F127 as a structure directing agent (SDA) under acidic aqueous conditions. The mesophase of the materials was investigated using small-angle powder X-ray diffraction and transmission electron microscopic (TEM) image analysis. N2 adsorption-desorption studies show that the BET surface area of CuMSC (214-407 m(2) g(-1)) is lower than that of pure silica (611 m(2) g(-1)) and has smaller average pore dimensions (4.0-5.0 nm), both prepared following the same synthetic route. The reduction of pore size and surface area points to incorporation of copper within the silicate network. FEG-SEM results suggest that the materials have a plate-like morphology and are composed of very tiny nanoparticles. EDS surface chemical analysis was utilized for the detection of the distribution of Si, O and Cu in the matrix. The FT IR spectral study suggests the complete removal of the surfactants from the calcined materials and the presence of Si-O-Cu bonds for high nominal contents. X-ray photoelectron spectroscopy (XPS) and UV-vis reflectance spectra show the oxidation state of copper and coordination mode, respectively. These mesoporous materials display a good catalytic activity in the oxidation of cyclohexane to cyclohexanone and cyclohexanol in the presence of the green oxidant hydrogen peroxide. The maximum yield (cyclohexanone and cyclohexanol) was ca. 29% and the TON (turnover number) was 276 under optimal reaction conditions. The good catalytic activity could be attributed to the large surface area and the presence of a high number of active sites located at the surface of the material, as well as to its stability. The catalysts showed negligible loss of activity after five cycles.

TiO2 nanoparticles, doped or co-doped with bismuth and/or yttrium (Bi/Y), were obtained by a sol–gel approach. GXRD and Raman revealed that TiO2 is under the form of anatase and that the introduction of the doping elements decreases its crystallinity. XPS studies confirmed, directly, the presence of dopant-O Ti bonds, at least for the Y case. Ground state diffuse reflectance absorption studies revealed that the Bi-doped and co-doped samples exhibit a large shift to the visible. The time resolved laser induced emission revealed that Bi and (Bi, Y) doping induces a decrease in the recombination rate of the photogenerated holes and electrons. The photocatalytic efficiency under visible irradiation of the unsupported and supported catalysts, in the form of thin film deposited on glass beads, was evaluated using benzoic acid, toluidine and alachlor as pollutant compounds. A meaningful enhancement in the photocatalytic activity was observed upon the co-doping with Y–Bi and is here assigned to the effect of the dopants on the recombination rate of the photogenerated holes and electrons.

Silver and gold nanoparticles (NPs) were generated via a mild wet-chemistry process in aqueous chitosan solutions. Gold and silver NPs were created in situ in presence of chitosan through the addition of the corresponding salt solution under a subsequent UV irradiation. Gold and silver NPs were also created by using a sequence of gold and then silver and vice versa. The amine function existing in the chain monomer operates as the anchoring centre of the metal NP, enabling thus a selective generation of the metal NPs through their nucleation followed by their growth. Ensuing hybrid systems were characterized by UV/vis spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) and Grazing Incident X-ray Diffraction (GIXRD). The NPs average sizes ranges from 10 to 40 nm for gold and 20 to 100 nm for silver. XPS studies on NPs generation through a sequence of gold followed by silver solutions suggest that gold cores enveloped by silver shells with some discontinuities exist.

Cellulose fibres obtained from sugarcane bagasse were submitted to a purification process, which consisted of an acid hydrolysis for elimination of the major part of lignin and hemicellulose. This was followed by a delignification process carried out in two steps to yield crude cellulose (CCell) fibres in the first one and with a subsequent bleaching in order to yield bleached cellulose fibres (BCell). Composites of crude and bleached cellulose fibres with hydrous niobium phosphate, cell/NbOPO4·nH2O, were subsequently synthesized. Scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction characterization of the obtained materials showed CCell/NbOPO4·nH2O and BCell/NbOPO4·nH2O are real composites. The nature of the cellulose (CCell or BCell) has an important role on the composites obtained, namely on the niobium salt composition at the composite surface. The synthesis of membranes of both cellulose and mixed matrix cellulose/NbOPO4·nH2O was only possible when the bleached cellulose was used.

Sherds representative of the Portuguese faience production of the early-16th century from the “Mata da Machada” kiln and from an archaeological excavation on a small urban site in the city of Aveiro (from late 15th to early 16th century) were studied with the use of non-invasive spectroscopies, namely: ground state diffuse reflectance absorption (GSDR), micro-Raman, Fourier-transform infrared (FT-IR) and proton induced X-ray (PIXE). These results were compared with the ones obtained for two Spanish productions, from Valencia and Seville, both from same period (late 15th century and 16th century), since it is well know that Portugal imported significant quantities of those goods from Spain at that time. The obtained results evidence a clear similarity in the micro-Raman spectrum in the glaze and clays of Portuguese pottery produced at “Mata da Machada” and sherds found at the mediaeval house of Homem Cristo Filho (HCF) street at Aveiro. The blue pigment in the sample from the household of Aveiro is a cobalt oxide that exists in the silicate glassy matrix in small amounts, which did not allow the formation of detectable cobalt silicate microcrystals. White glaze from Mata da Machada and Aveiro evidence tin oxide micro-Raman signatures superimposed on the bending and stretching bands of SiO2. All these are quite different from the Spanish products under study (Seville and Valencia), pointing to an earlier production of tin glaze earthenware in Portugal than the mid 16th century, as commonly assumed.

Mesoporous silica, SBA-15, decorated with different amounts of TiO 2 (anatase) were prepared by a sol-gel method followed by hydrothermal treatment and calcination, in the presence of a soft template, copolymer Pluronic 123. Tetraethyl orthosilicate (TEOS) was used as the SiO 2 precursor and commercially available TiO 2 anatase nanoparticles as the supported photocatalyst. The materials were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS), N 2 adsorption-desorption isotherms, raman spectroscopy, ground state diffuse reflectance (GSDR), laser induced luminescence (LIL) and X-ray photoelectron spectroscopy (XPS). The zeta potentials of the pure SBA-15, TiO 2 /SBA-15 substrate and the commercial anatase sample were monitored through a complete range of pH values. All the nanomaterials developed in this work were studied in terms of their photoactivity in the UV range and in the visible range, separately. In the first case, hydroxyl radicals ( OH) were confirmed to be the key active oxidizers in the photodegradation of the pesticide amicarbazone in aqueous medium. On the other hand, in the visible range, and following a dye sensitization process via a fluorescent rhodamine-like dye, two different mechanisms could be identified for the formation of the superoxide radical anion, O 2 − .

Carbon-supported PdP nanocatalysts, with 15 at.% P, were directly deposited onto a gas diffusion layer (carbon paper with Teflon) by electroless deposition. The electrochemical activity of the catalysts was determined in sulfuric acid solution with and without methanol. PdP alloys show a higher oxygen reduction reaction (ORR) activity than Pd, but comparable to that of Pt. Additionally, PdP catalysts have significantly higher catalytic activity for the ORR at high concentration of methanol. Rotating disk electrode (RDE) analysis revealed that the ORR on PdP catalyst follows the four-electron pathway. The catalysts were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements.

For the first time, bimetallic copper–thorium (Cu–Th–O), nickel–thorium (Ni–Th–O), and nickel–uranium (Ni–U–O) oxides were tested for the conversion of methane using N2O as oxidant. The behavior of the uranium and thorium catalysts is very different: at 10% methane isoconversion (700 °C), the production of C2 hydrocarbons is high over the uranium catalyst (≈80%), but the formation of oxidation products (CO2, CO) prevails over the thorium-based catalysts (≈85 and ≈15% selectivity to COx and C2). At higher temperature (750 °C), the formation of C2 hydrocarbons remains high over the uranium catalysts (conversion CH4 ≈ 20%, selectivity to C2 ≈ 60%), but the production of syngas is now very high over the thorium-based catalysts (conversion CH4 ≈ 50%, selectivity to CO and H2 ≈ 90% at 750 °C over Ni–Th–O) without formation of C2). This distinct behavior could not be assigned to the catalytic behavior of pure metal oxides or mechanical mixtures of single metal oxides, which is very different from that of the bim...

The atomic composition of layer-by-layer (LbL) films of the conductive polyelectrolyte poly(o-methoxyaniline) (POMA) alternated with the strong polyelectrolyte poly(styrene sulfonate) (PSS) was obtained from X-ray photoelectron spectroscopy (XPS), in order to study the influence of sodium chloride concentration of PSS aqueous solutions on the degree of ionization of polyelectrolytes in the film structure. The results revealed that the degree of ionization for both weak and strong polyelectrolytes decreases with NaCl concentration while the relative amount of counterions/co-ions increases. A larger number of ions, in comparison with the number of polylectrolytes ionic groups, indicate the formation of NaCl nanocrystals in the LbL film. However, results showed that some Cl atoms are being used in an extra chlorination chemical reaction with POMA. The number of water molecules retained in the films decreases with salt at a rate lower than that of the degree of ionization indicating that water molecules are close to salt ions. Moreover, the ratio water molecules per sodium assumes a value of 4 for films prepared without salt, which is the typical hydration number value for NaCl in solution, and decreases linearly with salt concentration pointing out to nanocrystals increase in size with salt concentration.

The assignment of silver oxidation state by XPS is a matter of large controversy. In fact, a large discrepancy of binding energy values for its most intense peak, Ag 3d, exists in the literature. Auger parameter is useful to distinguish Ag(0) from other oxidation states but useless for identifying other oxidation states. In this work, using salts where Ag exists solely in the form of Ag (I), the oxides Ag 2 O and AgO and a mechanical mixture of them, we could demonstrate that Ag(I) and Ag(III) are identifiable much more by their peak shape and width than by their absolute binding energy. For the first time, the XPS peak fit was performed in a way compatible with the presence of Ag(I) and Ag(III) in AgO with 1:1 (v/v) stoichiometry as predicted by other properties, namely its diamagnetism.

Platinum–ruthenium alloy electrocatalysts, for methanol oxidation reaction, were prepared on carbons thermally treated in helium atmosphere or chemically functionalized in H2O2, or in HNO3 + H2SO4 or in HNO3 solutions. The functionalized carbon that is produced using acid solutions contains more surface oxygenated functional groups than carbon treated with H2O2 solution or HeTT. The XRD/HR-TEM analysis have showed the existence of a higher alloying degree for Pt–Ru electrocatalysts supported on functionalized carbon, which present superior electrocatalytic performance, assessed by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy, as compared to electrocatalysts on unfunctionalized carbon. It also was found that Pt–Ru alloy electrocatalysts on functionalized carbon improve the reaction rate compared to Pt–Ru on carbons treated with H2O2 solution and thermally. A mechanism is discussed, where oxygenated groups generated from acid functionalization of carbon and adsorbed on Pt–Ru electrocatalysts are considered to enhance the electrocatalytic activity of the methanol oxidation reaction.

Films and fibres of cellulose were functionalised with silver and gold nanoparticles directly generated on the surface. The present method lays on the cellulose surface pre-modification, replacing some of the hydroxyl groups by amino functions, which selectively act as the seed coordination sites. Nanoparticles can then grow through the interaction with aqueous dilute solutions of AgNO3 or NaAuCl4 at room temperature, without adding any reducing agent. The procedure offers the advantage of limiting the generation of nanoparticles to the cellulose surface, leaving the dispersion medium completely exempt of them. The cellulose pre-modification also ensures chemical anchoring of the nanoparticles to the surface, avoiding any risk of particle desorption and extending the lifetime of the resulting hybrid materials. Evidence of the formation of the NPs on the cellulose surfaces was supported by FE-SEM, AFM, XPS and XRD. The method is simple and reproducible.