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Open access funding provided by FCT|FCCN (b-on). This work was funded by (a) Valorpneu S.A. through the INOV.AÇÃO 2018 Award; Associate Laboratory i4HB (LA/P/0140/2020); Maria Bernardo thanks FCT (Fundação para a Ciência e Tecnologia) for funding through program DL 57/2016 – Norma transitória. A.M. Ferraria thanks Instituto Superior Técnico for Scientific Employment contract IST-ID/131/2018. This work was also financially supported by GREENERING COST Action CA18224. Spent tire rubber-derived chars and their corresponding H3PO4 and CO2-activated chars were used as adsorbents in the recovery of Pb(II) ion and (W(VI)) oxyanion from synthetic solutions. The developed chars (both raw and activated) were thoroughly characterized to have insight about their textural and surface chemistry properties. H3PO4-activated chars presented lower surface areas than the raw chars and an acidic surface chemistry which affected the performance of these samples as they showed the lowest removals of the metallic ions. On the other hand, CO2-activated chars presented increased surface areas and increased mineral content compared to the raw chars, having presented higher uptake capacities for both Pb(II) (103–116 mg/g) and W(VI) (27–31 mg/g) ions. Cation exchange with Ca, Mg and Zn ions was appointed as a mechanism for Pb removal, as well as surface precipitation in the form of hydrocerussite (Pb3(CO3)2(OH)2). W(VI) adsorption might have been ruled by strong electrostatic attractions between the negatively charged tungstate species and the highly positively charged carbons’ surface. The results shown in this work allow concluding that the valorisation of spent tire rubber through pyrolysis and the subsequent activation of the obtained chars is an alternative and a feasible option to generate adsorbent materials with a high uptake capacity of critical metallic elements. publishersversion epub_ahead_of_print

New alternative routes to traditional Fischer-Tropsch Synthesis (FTS) must be established to get a more efficient process from the point of view of energy and sustainability. Solar photocatalytic-assisted FTS is a promising new path to obtain fuels from renewable resources. However, proper photocatalysts must be designed to enhance the photocatalytic activity under solar/visible radiation. In this work, Fe and Co-doped TiO2 catalysts were synthesized by a traditional impregnated method and by a hydrothermal route. The oxygen vacancies generation on TiO2 photocatalysts was studied by Raman, XPS and Diffuse Reflectance Spectroscopy (DRS) and correlated with the decrease of the band gap and the photoactivity in the syngas conversion into solar fuels under solar radiation. Metal doping and H2 reduction treatment favour the oxygen vacancies generation that decreases the band gap from 3.3 eV for P25 to values as low as 2.2 and 2.5 eV for Fe- and Co-doped TiO2. This lower band gap increases the methanation activity under solar radiation. Moreover, this metal doping does not only affect the band gap and CO methanation activity under solar radiation but also the CC coupling, favouring the production of ethanol. Thus, in presence of P25, only CO2 and CH4 are obtained whereas the addition of Fe and Co enhances the CH4 generation and favours ethanol production. Therefore, the present work opens new opportunities for the photocatalytic Fischer-Tropsch conversion (PFTS) of crude syngas, which can be obtained from biomass or MSW gasification, into fuels under solar light.

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.

Self-decontaminating cotton fabrics were designed, produced and characterized aiming at the decomposition of harmful molecules namely chemical warfare agents (CWAs) by photocatalysis under day light or indoor illumination. This was achieved through the creation of a hybrid organic-inorganic nanostructured textile composed of a thin layer of TiO2 nanoparticles (NPs) generated in situ and chemically immobilised on the cellulose chains of cotton fibres. TiO2 NPs were converted into anatase by a hydrothermal procedure at low temperature around 100°C. The fabrics covered with TiO2 nanoparticles were examined in terms of their chemical composition, morphology, crystallinity, ageing, robustness and photocatalytic properties. In the whole preparation of the photocatalytic fabrics, only environment-friendly solvents (water or alcohol) were used. One of the important achievements in this work was providing fabrics with suitable photocatalytic activity under visible light. This was reached through plasmonic photocatalysis by generating noble metal nanoparticles (Au, Ag) and/ or their halides (AgBr, AgCl) neighbouring or topping the TiO2 NPs in the fabrics. The kinetics of degradation of the different systems were analysed and proved that the resulting fabrics could efficiently decompose, under visible light, organic dyes and dimethyl methylphosphonate (DMMP), a CWA simulant.Graphical abstract

Hybrid Cotton-AgCl were prepared and found to be efficient antimicrobial agents for water disinfection under sunlight irradiation. AgCl was grafted on cotton by alternate immersion in AgNO3/KCl solutions, followed by a mild hydrothermal treatment. The as-prepared samples were characterized using a field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman, FTIRS and UV–vis ground state diffusion reflection (GSDR) spectroscopy, TGA, ICP and XRF. The microbial inactivation efficiency was tested using Escherichia coli (E. colis) and Staphylococcus aureus (S. aureus) as model strains of Gram negative and Gram positive bacteria, respectively. The as-prepared composites exhibit stronger antibacterial activity against both strains, with complete inactivation (107 cfu mL−1) of Escherichia coli within 15 min. The preparation method is environmentally friendly, facile to scale up and the AgCl/Ag junction is effectively bonded to the cotton fabric materials. These results show that cotton-AgCl is a promising plasmonic biocidal material for water disinfection under sunlight illumination as well as under indoor illumination.

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.

Cotton fabrics decorated with Cu

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.

In this study, cotton fabrics decorated with Ag/AgCl and Ag/AgBr NPs were produced by a simple hydrothermal treatment using AgCl and AgBr as precursors. Their morphological features as well as, chemical composition and structural and luminescence properties were compared. Their water disinfection aptitude against E. coli and S. aureus was also investigated under solar illumination in batch as well asin dynamic conditions. The highest activity was observed for Cot-Ag/AgCl with a quasi-complete inactivation of E. coli and S. aureus(1.5 × 107cfu mL−1) within 15 min illumination. Disinfection efficiency under continuous flow was also tested using a home-made photoreactor and the cotton fabrics with the most efficient photocatalyst (Ag/AgCl). It has shown to be efficient at least for 10 cycles revealing the robustness of the functionalization. The mechanism of photocatalytic disinfection was explained in terms of the surface plasmon resonance (SPR) induced by the presence of Ag NPs, the resulting holes, h+, being one of the most intervenient species in the disinfection mechanism. The difference in the photocatalytic efficiency between AgCl and AgBr functionalized cotton was attributed to differences in the carriers (h+and e-) lifetime. This work provides a proof of concept for the potential applicability of Cot-Ag/AgCl or Cot-Ag/AgBr for in-flow potabilization of water under solar illumination.

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.

Thin films of chitosan (CS) coated on glass substrates were used as support for the immobilization of nanostructures TiO2/ZnS via a mild chemical process followed by a hydrothermal treatment at 90 °C. The preparation route involved the coating of the CS film on the glass substrate followed by the deposition of a thin layer of Ti(OBu)4 precursor and immersion in a solution of Zn(O2CCH3)2 and Na2S. After a hydrothermal treatment at 90 °C, an even layer of TiO2 anatase decorated by ZnS nanorods was generated. Evidence of the formation of TiO2 anatase and ZnS was confirmed by XRD, Raman and XPS, and the morphology of the TiO2 layer and ZnS nanoparticles was analyzed by FE-SEM observations. The photocatalytic activity of the CS-TiO2-ZnS systems was evaluated by the degradation of a wide range of organic compounds including aromatic amines and carboxylic acids under a conventional halogen lamp.

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.

TiO2 has an easily tunable bandgap and a great absorption dye ability being widely used in many fields and in a number of fascinating applications. In this study, a wet chemical route, particularly a sol gel method using spin-coating is adopted to deposit TiO2 thin films onto soda lime glass and silicon substrates. TiO2 films were prepared by using an alcoholic solution of analytical reagent grade TiCl4 as titanium precursor at various experimental conditions. The accent was put on the conditions of preparation (spin time, spin speed, precursor concentration, number of coating layers etc), doping and on the post-deposit treatment namely the drying and the crystallization. The results showed a strong dependence on the drying temperature and on the temperature and duration of the crystallization. We found that the solution preparation and its color are important for getting a reproducible final product. The Raman spectra recorded at room temperature, showed the characteristic peaks of anatase which appear at 143 and around 396 cm−1. These peaks confirm the presence of TiO2. The X-ray diffraction (XRD) was used to identify the crystalline characteristic of TiO2 while the chemical states and relative amounts of the main elements existing in the samples were investigated by X-ray Photoelectron Spectroscopy (XPS). The morphology of the samples was visualized by AFM. We show by this work the feasibility to obtain different nanostructured TiO2 by changing the concentration of the solution. Photocatalytic activity of TiO2 films was evaluated. Rhodamine B is a recalcitrant dye and TiO2 was successfully tested for its oxidation. An abatement of 60% was obtained under sunlight for an initial concentration of 10 mg/l.

In the present work, a simple, reliable and cost-effective approach to functionalize cotton fabrics with Ag-TiO2 nanoparticles strongly bound to the fibres and with visible-light-responsive photo-activity is presented. The hybrid cotton-Ag-TiO2 fabrics were characterized by Raman, AFM, FE-SEM, TGA, XPS GSDR, and LIL to confirm the generation of metallic Ag nanoparticles and crystalline TiO2 and investigate how the concentration of Ag and TiO2 precursors affected the morphology and the luminescence properties of the nanostructured layer grafted on the cotton fibres. The photocatalytic activity of the cotton-Ag-TiO2 hybrid systems was evaluated by the discoloration of Remazol Brilliant Blue R in water under a xenon lamp irradiation (sunlight simulator) equipped with selective filters. The extended photocatalytic activity to the visible is here explained by a synergistic effect of both the excitation of the Ag NPs plasmon resonance by visible light and a delayed electron-hole recombination rate caused by Ag NPs, as it can be observed by UV absorption.

A simple approach to functionalize cotton fabrics with Au and TiO 2 nanostructured layer is presented. Hybrid fabrics (Cot-Au-TiO 2 ) are prepared through reduction of AuCl 4 − on cotton, followed by a non-aqueous sol-gel procedure using tetrabutyltitanate and a hydrothermal treatment at 110 °C. The generation of crystalline TiO 2 is confirmed by Raman spectroscopy. The fibres morphology and their roughness are characterized by AFM and FE-SEM. XPS shows how the concentration of the NPs precursors (Au and TiO 2 ) affects the layer composition. GSDR (Ground State Diffuse Reflectance Absorption Spectroscopy) and LIL (Laser induced luminescence) reveal a strong quenching effect induced by Au NPs. Photocatalytic activity measured through the Remazol Blue (RB) degradation reveals an enhancement under visible light, which increases with Au loading. This strong enhancement is explained through the surface plasmon resonance brought by Au NPs.

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.

It was demonstrated that the galvanostatic polarization of graphite electrodes in a two separated compartments cell generates simultaneously and straightforwardly, without further separation and functionalization, two distinct sets of hydrophilic carbon nanomaterials (EHC - Electrogenerated Hydrophilic Carbon), in anodic and cathodic compartments, respectively. The synthesized products comprise an amorphous carbonaceous material with aromatic sp2 carbon clusters, differing mainly on their oxidation degree. Surprisingly, it was found that nitrogen is incorporated in the carbon-based material along the electrolysis, which is provided by the N2 gas present in the air and/or aqueous medium. This phenomenon is explained on basis that very reactive species are formed during the electrodes polarization due to an anomalous high electric field generated along the galvanostatic polarization. In addition, it was also evidenced that ECH materials display a negative charge counterbalanced by sodium ions and unique optical properties, exhibiting deep ultraviolet emission (∼4.1 eV), as well as blue luminescence. It is foreseen that these findings will have important repercussions in the construction of optoelectronics devices, energy technology (supercapacitors, batteries and fuel cells) and biomedicine.

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.

Cotton fabrics decorated with Cu2O-Ag and Cu2O-Ag-AgBr NPs have been prepared using chemically immobilized Cu2O NPs as sacrificial templates. The objective is to prepare Cu2O-Ag heterostructures with Ag being intimately in contact with Cu2O NPs by galvanic replacement reactions without addition of any external reducing agent. Field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were used to study the morphology and the chemical composition of the nanocomposites formed on the fabrics. The morphology of the ensuing nanostructures was shown to be dependent on the Ag precursor, AgNO3, concentration. The antimicrobial activity of the treated fabrics was evaluated against Staphylococcus aureus and Escherichia coli as model strains of gram-negative and gram-positive, respectively. The results showed that the fabrics loaded with Cu2O-Ag and Cu2O-Ag-AgBr nanocomposites exhibited enhanced sterilization activity compared to the Cu2O treated fabric.

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.

Here we show that the main product released from graphite in the early stages of the anodic polarization is a carbon-based salt comprised of an amorphous carbonaceous material with delocalized negative charge, counterbalanced by sodium cations. Remarkably, this material shows a dual behaviour: it behaves as an electrolyte in aqueous medium, which has the ability to enhance the capacitive properties of the electrode-solution interface and in the solid state it can be used as an electrode material with meaningful capacitive properties.

O Livro do Desassossego pode ser considerado como uma obra atípica de Fernando Pessoa, tanto pela magnitude, comparativamente anómala, de alusões textuais à prosa francesa, como pelo uso potencialmente formalista da linguagem. Pretende-se compreender a relação que Soares cria entre o plano da percepção (exterior) e o plano da emoção (interior), com o objectivo de escrutinar a singularidade do seu livro.

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.

For the first time, herein is reported the use of a magnetic core-shell support for a C-scorpionate metallic complex. The prepared hybrid material, that consists on the C-scorpionate iron(II) complex [FeCl2{&kappa, 3-HC(pz)3}] (pz, pyrazolyl) immobilized at magnetic core-shell particles (Fe3O4/TiO2), was tested as catalyst for the oxidation of secondary alcohols using the model substrate 1-phenylethanol. Moreover, the application of alternative energy sources (e.g., ultrasounds, microwaves, mechanical or thermal) for the peroxidative alcohol oxidation using the magnetic heterogenized iron(II) scorpionate led to different/unusual outcomes that are presented and discussed.

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 (

Direct assembling of N-graphene, i.e. nitrogen doped graphene, in a controllable manner was achieved using microwave plasmas at atmospheric pressure conditions. The synthesis is accomplished via a single step using ethanol and ammonia as carbon and nitrogen precursors. Tailoring of the high-energy density plasma environment results in a selective synthesis of N-graphene (~0.4% doping level) in a narrow range of externally controlled operational conditions, i.e. precursor and background gas fluxes, plasma reactor design and microwave power. Applying infrared (IR) and ultraviolet (UV) irradiation to the flow of free-standing sheets in the post-plasma zone carries out changes in the percentage of sp2, the N doping type and the oxygen functionalities. X-ray photoelectron spectroscopy (XPS) revealed the relative extension of the graphene sheets π-system and the type of nitrogen chemical functions present in the lattice structure. Scanning Electron microscopy (SEM), Transmission Electron microscopy (TEM) and Raman spectroscopy were applied to determine morphological and structural characteristics of the sheets. Optical emission and FT-IR spectroscopy were applied for characterization of the high-energy density plasma environment and outlet gas stream. Electrochemical measurements were also performed to elucidate the electrochemical behavior of NG for supercapacitor applications.

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

Thin films of chitosan (CS) coated on glass substrates were used as support for the immobilization of nanostructures TiO

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

Cotton fibres were coated with nanolayers of TiO2, anatase, using a new approach based on a non-hydrolytic sol–gel process followed by a mild hydrothermal treatment at a temperature lower than 140 °C. The crystallization process was followed by Raman spectroscopy and XRD, and the change in the chemical environment of Ti resulting from the hydrothermal temperature was analyzed using XPS. Changes in the morphology of the ensuing NPs on the different cotton samples were studied by FE-SEM. UV-Vis absorption spectra and the luminescence properties of the TiO2, as well as their thermal properties, were also investigated. To explain the TiO2 crystallization at temperatures much lower than 350 °C, a growth mechanism of TiO2 nanocrystallites (diameter < 15 nm) was proposed to proceed via coordination and ligand exchange of Ti(OBu)4 with the cotton surface hydroxyl groups followed by edge-sharing polycondensation during the hydrothermal process. Also the presence of acetic acid was revealed crucial in the mechanism. The hybrid cotton–TiO2 was shown to exhibit a good photocatalytic activity for the degradation of an organic dye – Remazol Brilliant Blue R. The preparation technique is reliable, easy to implement and can be also applied to cotton fabrics to create self-cleaning and protection textiles under visible irradiation. Reusability of the cotton samples was investigated.