In the present thesis, research work to tackle challenges such as large-scale integration, selectivity and low efficiency around different types of nanocarbon based sensors is performed. The findings of these studies are given in the form of peer-reviewed publications and conclusions with future recommendations proposed as a summary. The work focuses on three key sensors types, gas sensors, biosensors and photodetectors. The first key aspect is dielectrophoretic (DEP) deposition of nitrogen doped single-walled carbon nanotubes (N-SWCNTs) and it is used as a route to large-scale assembly of increased reactivity, and thus selectivity, gas sensors. Furthermore, suspended SWCNTs and few layer graphene (FLG) devices are fabricated through a novel process which results in increased surface area transducers and low resistance SWCNTs based devices. Moreover, biosensors face similar challenges to gas sensors with the addition that their selectivity needs to be engineered through the formation of a biomimetic interface due to the nature of the analytes they are destined to investigate. Non-covalent functionalization of graphene using self-assembled phospholipid membranes delivered in a controlled and precise manner by dip-pen nanolithography (DPN) was demonstrated together with a high-speed fabrication process of bioassays onto patterned CVD graphene using a parallel tips system. Lastly, for the case of photodetectors, a SWCNT – nanoplasmonic system is proposed as a solution to the major issue of low quantum efficiency in low dimensionality materials. First, the performance of various geometries and arrangements of Au nanoparticles is explored by transferring a micromechanically exfoliated graphene flake onto them and studying the Raman enhancement that arises due to uncoupled and coupled near-fields. An increase of graphene Raman signal of 103 was observed for the areas suspended between two closely spaced dimers as a result of strong near field coupling when the polarisation of the incident light is parallel to the nanostructures axis. A large-scale integration of SWCNTs positioned in between the dimers using DEP is performed as a demonstration of the scalability of the system.

Il a été montré que l’addition de fluor en petite quantité sur la surface de nanotubes de carbone mono et multiparois engendre des radicaux à long temps de vie, caractérisés ici par RPE. Ce phénomène a pu être mis à profit pour initier la polymérisation du styrène, de l’acide acrylique ou encore de l’aniline. Les chaînes polymères formées apparaissent alors greffées à la surface des tubes. Il a été observé qu’un tel greffage facilite grandement la mise en suspension des nanotubes dans des solvants organiques. Ce travail s’est également attaché à exalter la complémentarité entre nouveaux matériaux fluorés et techniques avancées de mise en œuvre. Pour la première fois, l’incorporation de nanocarbones fluorés de différentes dimensionnalités (noirs de carbone, nanotubes, nanofibres, nanodisques) dans une matrice polymère électrofilée de polyvinylpyrrolidone a été réalisée. Les tissus nanocomposites microfibreux ainsi obtenus ont ensuite fait l’objet de traitements de re-fluoration en conditions douces, afin d’augmenter leur taux de fluor final et d’en modifier la texture. Les caractérisations par microscopie à balayage, RMN du solide et XPS ont permis d’établir que l’enrichissement en fluor de la matrice polymère et la structure multi échelle spectaculaire résultant du traitement de post-fluoration réalisé permettent d’induire la propriété de superhydrophobicité, mise en évidence par la mesure d’angles de contact avec l’eau supérieurs à 150°. / It has been shown that the addition of a small amount of fluorine to the surface of single and multi-walled carbon nanotubes generates long life-time radicals, here studied by EPR. The latter phenomenon can be usefully harnessed to initiate the polymerization of styrene, acrylic acid or still aniline. The polymeric chains thus formed appear to be grafted to the tubes surface. It has been observed that such a grafting process highly increases the dispersibility of tubes in some organic solvents. This work also focused on illustrating how advanced processing techniques may complement the assets of novel fluorinated materials. Hence, the inclusion of fluorinated nanocarbons with varied dimensionalities (carbon black, nanotubes, nanofibers, nanodisks) into an electrospun polyvinylpyrrolidone polymer matrix has been achieved for the first time. The nanocomposite-based microfibrous membranes thus obtained have been reacted with gaseous fluorine in mild conditions, in order to increase their final fluorine content and modify their texture. Characterizations performed using scanning electron microscopy, solid state NMR and XPS have shown that both the fluorination of the polymer matrix and quite spectacular multiscale structure resulting from etching by fluorine induce superhydrophobicity, evidenced through contact angles of the membranes with water exceeding 150°.

New derivatives of carbon nanostructures: nanotubes, nano-onions and nanocrystalline diamonds were obtained through fluorination and subsequent functionalization with sucrose. Chemically modified nanocarbons show high solubility in water, ethanol, DMF and can be used as biomaterials for medical applications. It was demonstrated that sucrose functionalized nanostructures can find applications in nanocomposites due to improved dispersion enabled by polyol functional groups. Additionally, pristine and chemically derivatized carbon nanotubes were studied as nanofillers in epoxy composites. Carbon nanotubes tailored with amino functionalities demonstrated better dispersion and crosslinking with epoxy polymer yielding improved tensile strength and elastic properties of nanocomposites. Reductive functionalization of nanocarbons, also known as Billups reaction, is a powerful method to yield nanomaterials with high degree of surface functionalization. In this method, nanocarbon salts prepared by treatment with lithium or sodium in liquid ammonia react readily with alkyl and aryl halides as well as bromo carboxylic acids. Functionalized materials are soluble in various organic or aqueous solvents. Water soluble nanodiamond derivatives were also synthesized by reductive functionalization of annealed nanodiamonds. Nanodiamond heat pretreatment was necessary to yield surface graphene layers and facilitate electron transfer from reducing agent to the surface of nanoparticles. Other carbon materials such as activated carbon and anthracite coal were also derivatized using reductive functionalization to yield water soluble activated carbon and partially soluble in organic solvents anthracite. It was shown that activated carbon can be effectively functionalized by Billups method. New derivatives of activated carbon can improve water treatment targeting specific impurities and bio active contaminants. It was demonstrated that functionalized carbon nanotubes are suitable for real time radiation measurements. Radiation sensor incorporating derivatized carbon nanotubes is lightweight and reusable. In summary, functionalization of carbon nanomaterials opens new avenues for processing and applications ranging from biomedicine to radiation sensing in space.

O presente trabalho trata da preparação e caracterização de três tipos de materiais, todos envolvendo hidróxidos duplos lamelares (HDLs) contendo íons cobalto e alumínio na composição das lamelas. Primeiramente, avaliou-se a influência de parâmetros de síntese na obtenção de HDLs intercalados com os ânions inorgânicos carbonato, cloreto e nitrato. Segundo dados de espectroscopia eletrônica UV-VIS, ressonância paramagnética eletrônica (EPR) e espectroscopia de fotoelétrons excitados por raios X (XPS), ocorre a oxidação parcial do Co2+ em Co3+ na lamela de HDL e, no caso do material contendo íon carbonato, observa-se a presença de radical carbonato, demonstrando a reatividade redox das matrizes com íons cobalto. A segunda parte do trabalho consistiu na intercalação do ânion derivado do ácido 2- aminotereftálico (ATA) em HDL. A presença do cátion cobalto nas lamelas e do grupo amino na espécie orgânica promoveu alterações significativas nas propriedades eletrônicas e térmicas do material (abreviado Co2Al-ATA). Assim como na primeira parte desta tese, as transformações ocorridas com o íon ATA devem incluir a formação inicial de um radical orgânico (de modo similar à polimerização da anilina), para o qual o agente oxidante é o íon Co3+ lamelar. Os dados de espectroscopia vibracional (no infravermelho e Raman) e de XPS mostram a presença de segmentos reduzidos (benzenóide) e oxidados (quinóides) na espécie intercalada. A solubilização do HDL em meio ácido permitiu isolar um material orgânico de cor preta que possui segmentos semiquinóides (radical orgânico) em sua estrutura, além dos reduzidos. A última etapa da presente tese consistiu em pirolisar o material Co2Al-ATA mencionado acima. Verificou-se que a alteração no procedimento de pirólise, como a temperatura, o desenho do forno, a forma do cadinho (cilíndrico ou barca), o tempo de resfriamento do sistema ou a atmosfera dinâmica ou estática, por exemplo, afetam as propriedades do produto final de decomposição. Nos compósitos obtidos, as fases inorgânicas provenientes da decomposição do HDL foram uma mistura de óxidos mistos de cobalto e alumínio (Co(CoxAl1-x)2O4), óxido de cobalto (CoO) e cobalto metálico. A fase de carbono apresentou perfil espectral de carbono grafítico nanocristalino e foi obtida em valores de temperatura de pirólise superiores a 800°C. Os compósitos contendo nanopartículas de cobalto metálico são ferromagnéticos. A reatividade redox dos HDLs de cobalto e as propriedades de seus produtos de decomposição apresentam potencial para aplicação em dispositivos eletroquímicos. / The present work reports the preparation and characterization of three types of materials, all involving layered double hydroxides (LDHs) containing cobalt and aluminum ions in the layer composition. First, the influence of synthetic parameters on the production of LDHs intercalated with the inorganic anions carbonate, chloride and nitrate was evaluated. According to UV-VIS electronic spectroscopy, electron paramagnetic resonance (EPR) and x-ray photoelectron spectroscopic (XPS) data, the partial oxidation of Co2+ to Co3+ occurs in the LDH layer and, in the case of the material containing carbonate ion, the presence of carbonate radical species demonstrates the redox reactivity of the matrices with cobalt ions. The second part of the work comprised the intercalation of the anion derived from 2- aminoterephthalic acid (ATA) in to LDH. The presence of the cobalt cation in the layer and the amino group in the organic species promoted significant changes in the electronic and thermal properties of the material (abbreviated Co2Al-ATA). As in the first part of this thesis, transformations occurring with the ATA ion should include the initial formation of an organic radical (similar to aniline polymerization), for which the oxidizing agent is the Co3+ ion in the layer. The vibrational (infrared and Raman) spectroscopy and XPS data show the presence of reduced (benzenoid) and oxidized (quinoids) segments in the intercalated species. The solubilization of HDL in acid medium allowed the isolation of a black organic material that has semiquinoid (organic radical) segments in its structure besides the reduced one. The last stage of the present thesis consisted of pyrolysis of the Co2Al-ATA material mentioned above. It was observed that the change in pyrolysis procedure, such as temperature, furnace design, crucible shape (bark or cylinder), system cooling time or dynamic or static atmosphere, for example, affects the properties of the final product of decomposition. In the obtained composites, the inorganic phases from the HDL decomposition were a mixture of mixed oxides of cobalt and aluminum (Co(CoxAl1-x)2O4), cobalt oxide (CoO) and metallic cobalt. The carbon phase showed nanocrystalline graphite carbon spectral profile and was obtained at pyrolysis temperature values above 800 °C. The composites containing metallic cobalt nanoparticles are ferromagnetic. The redox reactivity of HDLs containing cobalt and the properties of their decomposition products present potential for application in electrochemical devices

O presente trabalho trata da preparação e caracterização de três tipos de materiais, todos envolvendo hidróxidos duplos lamelares (HDLs) contendo íons cobalto e alumínio na composição das lamelas. Primeiramente, avaliou-se a influência de parâmetros de síntese na obtenção de HDLs intercalados com os ânions inorgânicos carbonato, cloreto e nitrato. Segundo dados de espectroscopia eletrônica UV-VIS, ressonância paramagnética eletrônica (EPR) e espectroscopia de fotoelétrons excitados por raios X (XPS), ocorre a oxidação parcial do Co2+ em Co3+ na lamela de HDL e, no caso do material contendo íon carbonato, observa-se a presença de radical carbonato, demonstrando a reatividade redox das matrizes com íons cobalto. A segunda parte do trabalho consistiu na intercalação do ânion derivado do ácido 2- aminotereftálico (ATA) em HDL. A presença do cátion cobalto nas lamelas e do grupo amino na espécie orgânica promoveu alterações significativas nas propriedades eletrônicas e térmicas do material (abreviado Co2Al-ATA). Assim como na primeira parte desta tese, as transformações ocorridas com o íon ATA devem incluir a formação inicial de um radical orgânico (de modo similar à polimerização da anilina), para o qual o agente oxidante é o íon Co3+ lamelar. Os dados de espectroscopia vibracional (no infravermelho e Raman) e de XPS mostram a presença de segmentos reduzidos (benzenóide) e oxidados (quinóides) na espécie intercalada. A solubilização do HDL em meio ácido permitiu isolar um material orgânico de cor preta que possui segmentos semiquinóides (radical orgânico) em sua estrutura, além dos reduzidos. A última etapa da presente tese consistiu em pirolisar o material Co2Al-ATA mencionado acima. Verificou-se que a alteração no procedimento de pirólise, como a temperatura, o desenho do forno, a forma do cadinho (cilíndrico ou barca), o tempo de resfriamento do sistema ou a atmosfera dinâmica ou estática, por exemplo, afetam as propriedades do produto final de decomposição. Nos compósitos obtidos, as fases inorgânicas provenientes da decomposição do HDL foram uma mistura de óxidos mistos de cobalto e alumínio (Co(CoxAl1-x)2O4), óxido de cobalto (CoO) e cobalto metálico. A fase de carbono apresentou perfil espectral de carbono grafítico nanocristalino e foi obtida em valores de temperatura de pirólise superiores a 800°C. Os compósitos contendo nanopartículas de cobalto metálico são ferromagnéticos. A reatividade redox dos HDLs de cobalto e as propriedades de seus produtos de decomposição apresentam potencial para aplicação em dispositivos eletroquímicos. / The present work reports the preparation and characterization of three types of materials, all involving layered double hydroxides (LDHs) containing cobalt and aluminum ions in the layer composition. First, the influence of synthetic parameters on the production of LDHs intercalated with the inorganic anions carbonate, chloride and nitrate was evaluated. According to UV-VIS electronic spectroscopy, electron paramagnetic resonance (EPR) and x-ray photoelectron spectroscopic (XPS) data, the partial oxidation of Co2+ to Co3+ occurs in the LDH layer and, in the case of the material containing carbonate ion, the presence of carbonate radical species demonstrates the redox reactivity of the matrices with cobalt ions. The second part of the work comprised the intercalation of the anion derived from 2- aminoterephthalic acid (ATA) in to LDH. The presence of the cobalt cation in the layer and the amino group in the organic species promoted significant changes in the electronic and thermal properties of the material (abbreviated Co2Al-ATA). As in the first part of this thesis, transformations occurring with the ATA ion should include the initial formation of an organic radical (similar to aniline polymerization), for which the oxidizing agent is the Co3+ ion in the layer. The vibrational (infrared and Raman) spectroscopy and XPS data show the presence of reduced (benzenoid) and oxidized (quinoids) segments in the intercalated species. The solubilization of HDL in acid medium allowed the isolation of a black organic material that has semiquinoid (organic radical) segments in its structure besides the reduced one. The last stage of the present thesis consisted of pyrolysis of the Co2Al-ATA material mentioned above. It was observed that the change in pyrolysis procedure, such as temperature, furnace design, crucible shape (bark or cylinder), system cooling time or dynamic or static atmosphere, for example, affects the properties of the final product of decomposition. In the obtained composites, the inorganic phases from the HDL decomposition were a mixture of mixed oxides of cobalt and aluminum (Co(CoxAl1-x)2O4), cobalt oxide (CoO) and metallic cobalt. The carbon phase showed nanocrystalline graphite carbon spectral profile and was obtained at pyrolysis temperature values above 800 °C. The composites containing metallic cobalt nanoparticles are ferromagnetic. The redox reactivity of HDLs containing cobalt and the properties of their decomposition products present potential for application in electrochemical devices

The thesis consists of four parts of which part 1 presents a brief overview of nanomaterials. Parts 2, 3 and 4 contain results of investigations of graphene, nanofilms of noble metal nanoparticles and ZnO nanostructures respectively. Investigations of graphene are described in Part 2 which consists of six chapters. In Chapter 2.1, changes in the electronic structure and properties of graphene induced by molecular charge-transfer have been discussed. Chapter 2.2 deals with the results of a study of the interaction of metal and metal oxide nanoparticles with graphene. Electrical and dielectric properties of graphene-polymer composites are presented in Chapter 2.3. Chapter 2.4 presents photo-thermal effects observed in laser-induced chemical transformations in graphene and other nanocarbons system. Chapter 2.5 describes the mechanical properties of polymer matrix composites reinforced by fewlayer graphene investigated by nano-indentation. The extraordinary synergy found in the mechanical properties of polymer matrix composites reinforced with two nanocarbons of different dimensionalities constitute the subject matter of Chapter 2.6. Investigations of noble metal nanoparticles have been described in Part 3. In Chapter 3.1, ferromagnetism exhibited by nanoparticles of noble metals is discussed in detail while Chapter 3.2 deals with surface-enhanced Raman scattering (SERS) of molecules adsorbed on nanocrystalline Au and Ag films formed at the organic–aqueous interface. Factors affecting laser-excited photoluminescence from ZnO nanostructures are examined in great detail in Part 4.

Plusieurs structures hiérarchisées des fluorures de fer et de nickel avec des matrices carbonées ou métalliques ont été obtenues par deux voies de fluoration : fluoration gaz-solide de nanoparticules par le fluor moléculaire pur ou par fluoration en milieu liquide via l’agent fluorant NH 4 F. Les différentes nanostructures des matériaux ainsi préparées ont été caractérisées par les techniques classiques de microscopies électroniques, de spectroscopies vibrationnelles (infrarouge et Raman) ou encore d’analyse thermogravimétrique. En complément, la diffraction des rayons X a permis d’étudier les matériaux tant à l’ordre global, qu’à l’ordre local par affinement et analyse PDF sous rayonnement synchrotron. Ainsi, les conditions de synthèse et les mécanismes de formation de différents assemblages de type 0D avec des structures core-shell nickel/fluorure de nickel ; mais aussi 1D avec des nanotubes de carbone double parois remplis par du fluorure de fer, ou encore 3D (« flower-like ») avec le greffage de nanoparticules de fluorures de nickel en surface de nanotubes de carbone simple ou multi parois ont pu être appréhendés. Finalement, les nanostructures les plus adaptées à la diffusion des ions lithium (particules core-shell et flower-like) ont finalement été testées comme matériaux de cathode. / Some hierarchized structures made of iron or nickel fluorides together with carbonaceous or metallic matrix were obtained owing to two fluorination ways : solid-gas fluorination proceeding by pure molecular fluorine gas or fluorination in liquid media using NH 4 F in solution. The different nanostructures have been characterized thanks to classical technics such as electronic microscopies, vibrational spectroscopies (infrared and Raman) or thermogravimetric analysis. Many attentions have been paid to determine the global and local structures by using X-ray diffraction, refinement of the diffraction pattern by Rietveld analysis or Pair Distribution Function analysis on pattern registered on synchrotron. So, the synthesis conditions and the formation mechanism of various assemblies have been carried out on 0D core-shell nickel/ nickel fluoride, 1D double-walled carbon nanotubes filled with iron fluoride or 3D single and multi-walled carbon nanotubes decorated with flower-like nickel fluoride. Finally, the nanostructures the most favorable to lithium-ion diffusion (core-shell and flower like nanostructures) have been used as electrode in secondary lithium batteries.

Carbon based nanostructures, such as fullerenes, carbon nanotubes and graphene showed a high potential for a vast of electronic and energy applications. However, properties of such materials in pristine forms can be insufficient to satisfy diverse specific demands, and tailoring their intrinsic properties is of increasing importance. In this work, different types of single-walled carbon nanotubes (SWCNTs) with controlled semiconducting fractions are p-/n-type doped by chemical doping in an attempt to tailor physical properties of the SWCNTs for the use in flexible thermoelectric (TE) devices and thermoplastic polymer-based conducting composites. Several p-/n-type doping schemes and an electronic type separation strategy have been developed to fulfill the task. A complete solution for efficient and scalable production of doped SWCNTs for the fabrication of flexible thermoelectric components is developed in this work. For p-type doping, a combined experimental and theoretical work demonstrates that boron atomic doping is an efficient way to simultaneously improve Seebeck coefficient (S) and electrical conductivity (σ) of SWCNT films, showing an increased thermoelectric power factor (S2σ) up to 255 μW/mK2 by a factor of 2.5 comparing to the pristine SWCNTs. For n-type doping, treatment of SWCNTs with potassium oxide and crown ether solution lead to a negative Seebeck coefficient of -30 μV/K and a promising S2σ up to 50 μW/mK2. A gel chromatography method has been developed to separate large-diameter (1.2-1.8nm) SWCNTs by electronic properties and to increase the purity of the sorted semiconducting carbon nanotubes (sc-SWCNTs) up to 95%. Effects of p-/n-type doping induced by different plasma treatments on the thermoelectric properties have been investigated for thin films made of sorted sc-SWCNTs. The high-purity sc-SWCNTs show significantly improved S of 125 μV/K. As the effects of p-type doping, air plasma treatments with proper duration (40s) lead to the increase of S, σ and thus S2σ up to 190 μW/mK2. The n-type doping for the SWCNT films have been performed via ammonia plasma treatment, and a negative S value of -80 μV/K has been achieved in air at 110oC, which is one of the best values ever reported for n-type carbon nanotube films. A flexible thermoelectric module was fabricated by printing ink made of the prepared boron doped SWCNTs and an organic solvent as an example for producing efficient all-carbon thermoelectric generators. At a temperature difference ΔT=60 K, the output voltage reaches 20 mV and the power output of 400 nW is obtained, although no “n”-legs are used in this module. At last, a work has been done on the development of melt mixed composites as TE materials, in which polypropylene is used as the matrix and boron-doped SWCNTs are used as conducting fillers. A percolation threshold lower than 0.25wt. % and a maximum conductivity up to 125 S/m at 5wt. % of SWCNT load have been achieved. The maximum conductivity is more than two times higher than that of the composites made with pristine SWCNTs as fillers.