The control of environmental pollution, particularly in wastewater treatment, is one of the major concerns of the 21st century. Among the currently available pollution control technologies, photocatalysis is one of the most promising and efficient approaches to the reduction of pollutants. Graphene, a carbon nanomaterial with specific physical and chemical properties, has been reported as a promising potential new catalyst material in this field. A Bi2WO6 photocatalyst modified with graphene oxide was synthesized in a two-step hydrothermal process. Compared with pure Bi2WO6, the modified photocatalyst with 1.2 wt% graphene oxide improved photoactivity during the degradation of rhodamine-B (RhB) dye pollutant, by facilitating the dissociation of photogenerated excitons, which in turn results in more O2- radicals. XRD characterization showed that the modification of Bi2WO6 with graphene oxide does not affect its structure or morphology. The adsorption properties of graphene also contribute to the improvement of photoactivity. Other parameters such as catalyst dosage, temperature and solution pH are studied, with the aim to improve the efficiency of RhB removal.

White light generation through phosphors excitation by UV-LED has become an important subject in WLED. In our study, compounds of SrSiO3¡GDy3+ white-emitting phosphors are synthesized via hydrothermal method. In this study, the effects of annealing temperature, annealing time, contents of Dy3+ on the relative emission intensity of the phosphors are judicially investigated. Meanwhile, WLED produces a plenty of heat energy to cause phosphors high temperature when WLED is excited by electrical energy. The emission spectra of the phosphors are investigated excited by Hg arc lamp (£f=365nm) under high temperature environment. Another, two distinct emission bands from SrSiO3¡GDy3+ phosphors are found to be around 480nm and 572nm when the phosphor is excited by Hg arc lamp(£f=365nm). The combination of these two emissions forms a white light like color to naked eyes, showing that SrSiO3¡GDy3+ presents to be a promising phosphor for applications in fabricating white-light-emitting diodes through UV pumping.

Metal nanoparticles have unique optical, electrical, catalytic and mechanical properties, which lead them to various applications in nanotechnology. In particular, noble metal nanowires are attracting growing attention due to their potential applications such as in opto-electronic devices and transparent conductive contacts (TCCs). There are two general approaches to synthesize nanowires: template-assisted and solution phase methods. However, these synthesis approaches have various disadvantages. For example, removal of the template to ensure the purity of the synthesized nanowires is the major problem. In solution methods like the widely used &ldquo / seed mediated growth method&rdquo / , nanowires are synthesized in low yield with the significant amount of by-products and requirement of purification is a major problem for further applications. Among all solution based methods, hydrothermal process is a very promising way of preparing gold (Au) nanowires in high yield and structural purity. In this thesis, hydrothermal process was modified to synthesize high aspect ratio Au nanowires with high morphological purity. Parametric study was performed to examine the effect of surfactant concentration, reaction time and temperature on the quality of products. The optimum conditions were determined for two different surfactant molecules (hexamethylenetetramine (HMTA) and ethylenediaminetetraacetic acid (Na2-EDTA)). Characterization of the products was done by detailed analysis via scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-Ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS). The analyses demonstrated that the Au nanowires synthesized at optimum conditions have high aspect ratio (diameters 50-110 nm range and lengths in micrometer range) and high structural purity.

The ZSM-12 zeolite is high silica material, with a one-dimensional pore structure that makes it presents a high performance as a catalyst in the hydroisomerization of hydrocarbons. For the synthesis of ZSM-12 in most cases, reagents are required that results in the process, for example, the use of organic agents drivers structure and / or a reactant to some sources have different values, the most interesting use which has the lowest value to make the synthesis more feasible in industrial scale. In this work we developed a synthesis route of zeolite ZSM-12 using a silica source more viable than the silica gel, sodium metassilicate. Samples were synthesized by the hydrothermal method at a temperature of 160 ° C using the following reagents: silica gel, sodium metassilicate, sodium hydroxide, pseudobohemita, tetraethylammonium hydroxide, sulfuric acid. After synthesis the samples were characterized by X-ray diffraction (XRD), absorption spectroscopy in the infrared (FT-IR), thermal analysis (TG / DTA), determination of surface area (BET) and scanning electron microscopy (MEV) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A ZSM-12 é uma zeólita rica em sílica, com uma estrutura de poros unidimensionais que faz com que ela apresente um grande desempenho como catalisador em reações de hidroisomerização de hidrocarbonetos. Para a síntese da ZSM-12, na maioria das vezes, são necessários reagentes que encarecem o processo, como por exemplo, o uso de agentes orgânicos direcionadores de estrutura ou/e algumas fontes de um reagente possuir valores diversos, sendo o mais interessante usar o que tem o valor mais baixo para tornar a síntese mais viável em escala industrial. No presente trabalho foi desenvolvida uma rota de síntese da zeólita ZSM-12 utilizando uma fonte de sílica mais viável que a sílica gel, o metassilicato de sódio. As amostras foram sintetizadas pelo método hidrotérmico à temperatura de 160°C, utilizando os seguintes reagentes: sílica gel, metassilicato de sódio, hidróxido de sódio, pseudobohemita, hidróxido de tetraetilamônio, ácido sulfúrico. Após as sínteses as amostras obtidas foram caracterizadas por difração de raios X (DRX), espectroscopia de absorção na região do infravermelho (FT-IR), análises térmicas (TG/DTA), determinação da área superficial (BET) e microscopia eletrônica de varredura (MEV).

Transparent conducting oxide (TCOs) thin films, including non-stoichiometric tin doped indium oxide (ITO) and aluminium doped zinc oxide (AZO), have found considerable applications in various displays, solar cells, and electrochromic devices, due to their unique combination of high electrical conductivity and optical transparency. TCO thin films are normally fabricated by sputtering, thermal vapour deposition and sol-gel method. Among them, sol-gel processing, which was employed in this project, is no doubt the simplest and cheapest processing method, The main objectives of this project were to produce indium tin oxides (ITO) and zinc aluminium oxides (AZO) nanoparticles with controlled particle size and morphology and to fabricate TCO thin films with high optical transmittance and electrical conductivity. In this research, hydrothermal method was used to synthesise ITO and AZO nanoparticles. Tin oxides, zinc oxides, ITO and AZO particles with the particle size ranging from 10 nm to several micrometers and different morphologies were synthesised through controlling the starting salts, alkaline solvents and hydrothermal treatment conditions. ITO and AZO thin films were fabricated via sol-gel technique through dip coating method. The effects of the starting salts, alkaline solvents, surfactant additives and coating and calcination conditions on the formation of thin films were investigated. XRD, TEM, FEG-SEM, DSC-TGA, UV-Vis spectrometer and four-point probe resistance meter were used to characterise the crystallinity, particle size, morphology, optical transmittance and sheet resistance of the particles and thin films. Crack-free thin films with high optical transmittance (>80% at 550 nm) and low sheet resistances (2.11 kΩ for ITO and 26.4 kΩ for AZO) were obtained in optimised processing conditions.

Titanatos nanoestruturados (TNS) obtidos pelo tratamento hidrotérmico de TiO2 são semicondutores muito estudados por suas propriedades de alta área superficial e capacidade de troca iônica. No entanto, sua estrutura cristalina e a influência das condições de síntese e pós-tratamento ainda são motivos de controvérsia. Neste estudo, TNSs foram produzidos em diversas condições e submetidos a diferentes tipos de tratamento ácido e térmico. Os materiais foram caracterizados por difratometria de raios X (DRX), espectroscopias vibracionais (Raman e FTIR), espectroscopia de refletância difusa (DRS), análise térmica (TG, DTG e DSC), análise textural por adsorção de N2 a 77 K, análise química por ICP-OES, e microscopia eletrônica de transmissão. Acompanhando a transformação hidrotérmica de TiO2 (anatase) nanocristalino obtido em laboratório com o tempo, observou-se que os nanocristais de TiO2 se transformam em estruturas lamelares com formato de folhas entre 3h e 12h. As nanofolhas se enrolam parcial ou totalmente formando nanotubos. A transformação da morfologia é acompanhada por uma transformação de fase de anatase para uma fase titanato lamelar, que se completa entre 12h e 24h. Utilizando TiO2 P25 como precursor, observou-se que as amostras obtidas apresentam alto teor de Na+, que é progressivamente eliminado por lavagens do sólido com H2O ou solução ácida. Quanto menor o pH de equilíbrio da suspensão, menor foi o teor de Na+ até o limite de pH 2, em que esse cátion foi praticamente eliminado. A diminuição do teor de sódio foi acompanhada de aumento da área superficial (BET, 155 e 205 m2.g-1 para pH 9 e 2, respectivamente); aumento do espaço interlamelar; diminuição da cristalinidade; e diminuição do bandgap (3,60 e 3,45 para pH 9 e 2, respectivamente). Em pH 1,5, ocorreu ainda maior aumento do espaço interlamelar e da área superficial (368 m2.g-1) indicando que a troca iônica de Na+ por H3O+ não é unicamente responsável pelas transformações estruturais que ocorrem durante a neutralização de TNSs. A desidratação em baixa temperatura (até 150 °C) sofrida por TNSs acidificados é irreversível, levando à diminuição do espaço interlamelar, e formação de vacâncias de oxigênio responsáveis pela absorção de radiação acima de 420 nm (visível). A transformação de fase de titanato para anatase ocorreu à temperatura ambiente quando a neutralização foi feita com HF; entre 300 e 400 °C quando feita com HCl, HNO3, H2SO4 ou ácido acético; e acima de 600 °C quando usado H3PO4. Foi possível inserir diferentes quantidades de prata em TNS através da suspensão dos sólidos em solução de AgNO3. A reação levou à formação de nanopartículas cristalinas de 3 a 5 nm, contendo prata, na superfície das partículas de TNS. Ag+ foi reduzido a Ag0 pelo tratamento térmico das amostras a 250 °C em presença de H2(g). Essas amostras apresentaram absorção de radiação em todo o espectro visível e menor bandgap (3,06 em amostra contendo 3% de Ag, em massa). Em amostras com pouca quantidade de prata (menos de 0,05% em massa), foram observadas bandas largas de absorção (DRS) de ressonância de plasmon de superfície quando calcinadas a 250 °C em H2(g). / Titanate nanostructures (TNS) obtained by the hydrothermal treatment of TiO2 are extensively studied due to their high surface area and ion-exchange ability. However, their crystal structure and influence of synthesis and post-treatment conditions are still under debate. In this study, TNSs were produced under different synthetic conditions and underwent different types of acid and thermal treatments. The materials were characterized by means of X-ray diffractometry (XRD), vibrational spectroscopy (Raman and FTIR), diffuse reflectance spectroscopy (DRS), thermal analysis (TG, DTG and DSC), textural analysis by N2 adsorption at 77 K, chemical analysis by ICP-OES, and transmission electron microscopy (TEM). Following the hydrothermal transformation of homemade crystalline TiO2 (anatase) with time, we observed that TiO2 nanocrystals change into lamellar sheet-like structures between 3h and 12h. The nanosheets roll up partial or totally, thus forming nanotubes. The morphological transformation is accompanied by a phase transformation from anatase to lamellar titanate, which is completed between 12h and 24h. Using TiO2 P25 as precursor, we observed that as-obtained samples have a high Na+ content, which is progressively removed by washing the solids with H2O or acidic solution. The smaller the suspensions equilibrium pH, the smaller the Na+ content to the limit of pH 2, when the removal of this cation was complete. The decrease in sodium content was followed by an increase in the surface area (BET, 155 and 205 m2.g-1 at pH 9 and 2, respectively); an increase in the interlamellar distance; a decrease in crystallinity; and a decrease in bandgap energy (from 3.60 eV at pH 9 to 3.45 eV at pH 7). After treating at pH 1.5, the interlamellar distance and the surface area (368 m2.g-1) increased further, suggesting that the Na+ to H3O+ ion-exchange is not the only factor in the structural transformations that take place during the acid treatment of TNSs. Acidic TNSs undergo an irreversible dehydration process at low temperature (150 °C). It leads to the decrease of the interlamellar distance and to the formation of oxygen vacancies responsible for the absorption of radiation in the visible range (> 420 nm). The phase transformation of the titanate phase to TiO2 anatase took place at room temperature when the TNS was treated with HF; between 300 and 400 °C for samples neutralized with HCl, HNO3, H2SO4 or acetic acid; and over 600 °C when H3PO4 was used. It was possible to insert different amounts of silver by the immersion of the solids in AgNO3 solution, leading to the formation of nanocrystalline-silver-containing nanoparticles (3 to 5 nm) on the surface of the TNS particles. Ag+ was reduced to Ag0 by heat treating the samples at 250 °C in presence of H2(g). These materials showed absorption of radiation in entire visible spectrum and narrowed bandgap energy (3,06 eV for sample with 3wt% of Ag). Samples containing low amounts of Ag (less than 0,05 wt%) showed a wide surface plasmon resonance band (DRS) when calcined at 250 °C under H2(g).

Titanatos nanoestruturados (TNS) obtidos pelo tratamento hidrotérmico de TiO2 são semicondutores muito estudados por suas propriedades de alta área superficial e capacidade de troca iônica. No entanto, sua estrutura cristalina e a influência das condições de síntese e pós-tratamento ainda são motivos de controvérsia. Neste estudo, TNSs foram produzidos em diversas condições e submetidos a diferentes tipos de tratamento ácido e térmico. Os materiais foram caracterizados por difratometria de raios X (DRX), espectroscopias vibracionais (Raman e FTIR), espectroscopia de refletância difusa (DRS), análise térmica (TG, DTG e DSC), análise textural por adsorção de N2 a 77 K, análise química por ICP-OES, e microscopia eletrônica de transmissão. Acompanhando a transformação hidrotérmica de TiO2 (anatase) nanocristalino obtido em laboratório com o tempo, observou-se que os nanocristais de TiO2 se transformam em estruturas lamelares com formato de folhas entre 3h e 12h. As nanofolhas se enrolam parcial ou totalmente formando nanotubos. A transformação da morfologia é acompanhada por uma transformação de fase de anatase para uma fase titanato lamelar, que se completa entre 12h e 24h. Utilizando TiO2 P25 como precursor, observou-se que as amostras obtidas apresentam alto teor de Na+, que é progressivamente eliminado por lavagens do sólido com H2O ou solução ácida. Quanto menor o pH de equilíbrio da suspensão, menor foi o teor de Na+ até o limite de pH 2, em que esse cátion foi praticamente eliminado. A diminuição do teor de sódio foi acompanhada de aumento da área superficial (BET, 155 e 205 m2.g-1 para pH 9 e 2, respectivamente); aumento do espaço interlamelar; diminuição da cristalinidade; e diminuição do bandgap (3,60 e 3,45 para pH 9 e 2, respectivamente). Em pH 1,5, ocorreu ainda maior aumento do espaço interlamelar e da área superficial (368 m2.g-1) indicando que a troca iônica de Na+ por H3O+ não é unicamente responsável pelas transformações estruturais que ocorrem durante a neutralização de TNSs. A desidratação em baixa temperatura (até 150 °C) sofrida por TNSs acidificados é irreversível, levando à diminuição do espaço interlamelar, e formação de vacâncias de oxigênio responsáveis pela absorção de radiação acima de 420 nm (visível). A transformação de fase de titanato para anatase ocorreu à temperatura ambiente quando a neutralização foi feita com HF; entre 300 e 400 °C quando feita com HCl, HNO3, H2SO4 ou ácido acético; e acima de 600 °C quando usado H3PO4. Foi possível inserir diferentes quantidades de prata em TNS através da suspensão dos sólidos em solução de AgNO3. A reação levou à formação de nanopartículas cristalinas de 3 a 5 nm, contendo prata, na superfície das partículas de TNS. Ag+ foi reduzido a Ag0 pelo tratamento térmico das amostras a 250 °C em presença de H2(g). Essas amostras apresentaram absorção de radiação em todo o espectro visível e menor bandgap (3,06 em amostra contendo 3% de Ag, em massa). Em amostras com pouca quantidade de prata (menos de 0,05% em massa), foram observadas bandas largas de absorção (DRS) de ressonância de plasmon de superfície quando calcinadas a 250 °C em H2(g). / Titanate nanostructures (TNS) obtained by the hydrothermal treatment of TiO2 are extensively studied due to their high surface area and ion-exchange ability. However, their crystal structure and influence of synthesis and post-treatment conditions are still under debate. In this study, TNSs were produced under different synthetic conditions and underwent different types of acid and thermal treatments. The materials were characterized by means of X-ray diffractometry (XRD), vibrational spectroscopy (Raman and FTIR), diffuse reflectance spectroscopy (DRS), thermal analysis (TG, DTG and DSC), textural analysis by N2 adsorption at 77 K, chemical analysis by ICP-OES, and transmission electron microscopy (TEM). Following the hydrothermal transformation of homemade crystalline TiO2 (anatase) with time, we observed that TiO2 nanocrystals change into lamellar sheet-like structures between 3h and 12h. The nanosheets roll up partial or totally, thus forming nanotubes. The morphological transformation is accompanied by a phase transformation from anatase to lamellar titanate, which is completed between 12h and 24h. Using TiO2 P25 as precursor, we observed that as-obtained samples have a high Na+ content, which is progressively removed by washing the solids with H2O or acidic solution. The smaller the suspensions equilibrium pH, the smaller the Na+ content to the limit of pH 2, when the removal of this cation was complete. The decrease in sodium content was followed by an increase in the surface area (BET, 155 and 205 m2.g-1 at pH 9 and 2, respectively); an increase in the interlamellar distance; a decrease in crystallinity; and a decrease in bandgap energy (from 3.60 eV at pH 9 to 3.45 eV at pH 7). After treating at pH 1.5, the interlamellar distance and the surface area (368 m2.g-1) increased further, suggesting that the Na+ to H3O+ ion-exchange is not the only factor in the structural transformations that take place during the acid treatment of TNSs. Acidic TNSs undergo an irreversible dehydration process at low temperature (150 °C). It leads to the decrease of the interlamellar distance and to the formation of oxygen vacancies responsible for the absorption of radiation in the visible range (> 420 nm). The phase transformation of the titanate phase to TiO2 anatase took place at room temperature when the TNS was treated with HF; between 300 and 400 °C for samples neutralized with HCl, HNO3, H2SO4 or acetic acid; and over 600 °C when H3PO4 was used. It was possible to insert different amounts of silver by the immersion of the solids in AgNO3 solution, leading to the formation of nanocrystalline-silver-containing nanoparticles (3 to 5 nm) on the surface of the TNS particles. Ag+ was reduced to Ag0 by heat treating the samples at 250 °C in presence of H2(g). These materials showed absorption of radiation in entire visible spectrum and narrowed bandgap energy (3,06 eV for sample with 3wt% of Ag). Samples containing low amounts of Ag (less than 0,05 wt%) showed a wide surface plasmon resonance band (DRS) when calcined at 250 °C under H2(g).

Nanotechnology is a technology of the design and the applications of nanoscale materials with their fundamentally new properties and functions. Nanosensor devices based on nanomaterials provide very fast response, low-cost, long-life time, easy to use for unskilled users, and provide high-efficiency. 1-D ZnO nanostructures materials have great potential applications in various sensing applications. ZnO is a wide band gap (3.37 eV at room temperature) semiconductor materials having large exciton binding energy (60 meV) and excellent chemical stability, electrical, optical, piezoelectric and pyroelectric properties. By doping the transition metals (TM) into ZnO matrix, the properties of ZnO nanostructures can be tuned and its room  temperature ferromagnetic behavior can be enhanced, which provide the TM-doped ZnO nanostructures as promising candidate for optoelectronic, spintronics and high performance sensors based devices. The synthesis of ZnO and TM-doped ZnO nanostructures via the low temperature hydrothermal method is considered a promising technique due to low cost, environmental friendly, simple solution process, diverse 1-D ZnO nanostructures can be achieved, and large scale production on any type of substrate, and their properties can be controlled by the growth parameters. However, to synthesize 1-D ZnO and TM-doped ZnO nanostructures with controlled shape, structure and uniform size distribution on large area substrates with desirable properties, low cost and simple processes are of high interest and it is a big challenge at present. The main purpose of this dissertation aims to develop new techniques to synthesize 1-D ZnO and (Fe, Mn)-doped ZnO nanostructures via the hydrothermal method, to characterize and to enhance their functional properties for developing sensing devices such as biosensors for clinical diagnoses and environmental monitoring applications, piezoresistive sensors and UV photodetector. The first part of the dissertation deals with the hydrothermal synthesis of ZnO nanostructures with controlled shape, structure and uniform size distribution under different conditions and their structural characterization. The possible parameters affecting the growth which can alter the morphology, uniformity and properties of the ZnO nanostructures were investigated. Well-aligned ZnO nanorods have been fabricated for high sensitive piezoresistive sensor. The development of creatinine biosensor for clinical diagnoses purpose and the development of glucose biosensor for indirect determination of mercury ions for an inexpensive and unskilled users for environmental monitoring applications with highly sensitive, selective, stable, reproducible, interference resistant, and fast response time have been fabricated based on ZnO nanorods. The second part of the dissertation presents a new hydrothermal synthesis of (Fe, Mn)-doped-ZnO nanostructures under different preparation conditions, their properties characterization and the fabrication of piezoresistive sensors and UV photodetectors based devices were demonstrated. The solution preparation condition and growth parameters that influences on the morphology, structures and properties of the nanostructures were investigated. The fabrication of Mn-doped-ZnO NRs/PEDOT:PSS Schottky diodes used as high performance piezoresistive sensor and UV photodetector have been studied and Fe-doped ZnO NRs/FTO Schottky diode has also been fabricated for high performance of UV photodetector. Finally, a brief outlook into future challenges and relating new opportunities are presented in the last part of the dissertation.

The objectives of this project were to synthesise semi-conducting ceramic nanoparticles including zinc oxide (ZnO) and aluminium doped zinc oxide (AZO) through a wet chemistry route to obtain nanoparticles with a controlled size and morphology. Wet chemistry methods (co-precipitation method and hydrothermal method) were used to synthesise ZnO and AZO particles. In the synthesis, various compounds and morphologies were synthesised. ZnO, Zn(OH)2 and unknown phases were co-precipitated, with only ZnO obtained following hydrothermal treatment. Morphologies ranging from platelets, flower-like, nanorods and microflowers were obtained. Particle sizes as small as 11 nm were characterised. Nanorod and nanosphere AZO particles were also synthesised with the results indicated the average grain size decreasing with increasing Al atomic content. Three orthogonal arrays were carried out to investigate the effects of the reaction parameters on the size and morphology of ZnO particles. The applicability of the orthogonal array was successful, with the optimum parameters of both hydrothermal experiments showing an increase in aspect ratio. The L/D ratio of ZnO nanorods obtained in the confirmation experiment increased to 9.4 which was larger than the ZnO synthesised using other reaction conditions (1.0 8.0). Scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterise the properties of the obtained particles. Morphology, crystallinity and particle size were all characterised.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nanostructured carbon materials production can constitute an alternative for a sustainable management of residues originated from petrochemical waste and agriculture activities, toward the development of multifunctional ―green‖ materials. The coconut processing industry generate a significant amount of waste (45% of mass). The shell, fibers and coconut coir dust have been studied extensively to produce conventional carbon materials. The goal of this work was to produce carbon-clay nanocomposites and carbon nanostructures by hydrothermal route. By using coconut fiber residue as carbonaceous precursor along with lamellar (montmorillonite and kaolinite) and fibrous clays (sepiolite and attapulgite).The obtained materials were characterized by X-ray diffraction, Raman and Infrared spectroscopy, thermogravimetry, scanning and transmission electron microscopy and area and porosity measurements by BET. Carbon phase formation was indicated by infrared results with bands at ~ 1444 cm-1 and ~ 1512 cm-1 assigned to C=C of aromatic groups. Raman spectroscopy results showed presence of carbonaceous species by the appearance of D and G bands assigned to disordered and graphitic crystallites, respectively. The estimated particle size based on Raman bands was found between 8-33 nm. SEM results showed that the morphology of coconut coir dust was preserved and all materials showed overlapping sheets and plates formation. In transmission electron microscopy (TEM) images it was possible to observe three types of carbon nanostructures: sheets, fibers and nanoparticles. It was observed the formation of very thin amorphous sheets, as well as the presence of partially ordered graphitic domains and disperse carbon nanoparticles. / A produção de materiais de carbono nanoestruturados pode constituir uma alternativa para a reutilização de resíduos provenientes da indústria petroquímica e atividades agrícolas, abrindo um caminho para o desenvolvimento de materiais ―verdes‖ multifuncionais. Da indústria do processamento do coco, origina-se uma quantidade significativa de resíduos (45% do fruto). A casca, fibras e pó de coco são estudados extensivamente para a produção de materiais de carbono convencionais. A proposta deste trabalho foi produzir nanocompósitos de carbono-argila e nanoestruturas de carbono, via rota hidrotérmica. Para tanto foi utilizado o pó de coco in natura como precursor carbonáceo e argilas lamelares (montmorillonita e caulinita) e fibrosas (atapulgita e sepiolita). Os materiais obtidos foram caracterizados por difração de Raios-X, espectroscopia Raman e no Infravermelho, Termogravimetria, Microscopia eletrônica de Varredura (MEV) e Transmissão (MET), e medidas de área superficial e porosidade por BET. A formação de carbono foi indicada pelos resultados de infravermelho com bandas em ~1444 cm-1 e ~1512 cm-1 atribuídas a C=C de grupos aromáticos. Os resultados de espectroscopia Raman evidenciaram a presença de espécies carbonáceas pelo aparecimento das bandas D e G atribuídas, respectivamente, a presença de desordem e cristalitos de grafite. A faixa de tamanho de partícula estimada a partir das bandas Raman está entre 8-33 nm. Os resultados de MEV mostraram que a morfologia do pó de coco foi preservada e todos os materiais obtidos apresentaram a formação de folhas sobrepostas e placas. Nas imagens de microscopia eletrônica de transmissão (MET) foi possível observar a formação de três tipos de nanoestruturas de carbono: folhas, fibras e nanopartículas. Observou-se a formação de folhas muito finas, de caráter predominantemente amorfo, bem como a presença de domínios grafiticos parcialmente ordenados, e nanopartículas de carbono dispersas.