L’importance des systèmes temps-réels embarqués dans les sociétés industrialisées modernes en font un terrain d’application privilégié pour les méthodes formelles. La prépondérance des contraintes temporelles dans les spécifications de ces systèmes motive la mise au point de solutions spécifiques. Cette thèse s’intéresse à une classe de systèmes temps-réels incluant ceux développés avec la chaîne d’outils OASIS, développée au CEA LIST. Nos travaux portent sur la notion de délai de bout-en-bout, que nous proposons de modéliser comme une contrainte temporelle concernant l’influence du flot d’informations des entrées sur celui des sorties. Afin de répondre à la complexité croissante des systèmes temps-réels, nous étudions l’applicabilité de cette notion nouvelle au développement incrémental par raffinement et par composition. Le raffinement est abordé sous l’angle de la conservation de propriétés garantes de la correction du système au cours du processus de développement. Nous délimitons les conditions nécessaires et suffisantes à la conservation du délai de bout-en-bout lors d’un tel processus. De même, nous donnons des conditions suffisantes pour permettre le calcul du délai de bout-en-bout de manière compositionnelle. Combinés, ces résultats permettent d’établir un formalisme permettant la preuve du délai de bout-en-bout lors d’une démarche de développement incrémentale. / Real-time embedded systems are at the core of modern industrialized societies. They are a privileged target for the application of formal methods. The importance of real-time constraints in the specification of these systems requires the design of ad-hoc solutions. This work considers a class of real-time systems including those developed using OASIS, a tool-chain targeting hard real-time embedded systems developed at CEA LIST. We study the notion of end-to-end delay, which we propose to model as a constraint bearing directly on the influence of the input information flow over the output information flow . In order to cope with the growing complexity of real-time embedded systems, we study the possibility to apply this new notion of delay to the incremental development of such systems, by using both stepwise refinement and composition operators. We define the necessary and sufficient conditions to the preservation of the end-to-end delay by stepwise refinement. Similarly, we give sufficient conditions to compute the end-to-end delay in a compositional fashion. Together, these results permit to establish a formalism allowing to prove end-to-end delay properties in stepwise development methodologies.

The numerical solution of the convection-diffusion-reaction problem is considered in two and three dimensions. A stabilized finite element method of Galerkin/Least squares type accomodates diffusion-dominated as well as convection- and/or reaction- dominated situations. The resolution of boundary layers occuring in the singularly perturbed case is accomplished using anisotropic mesh refinement in boundary layer regions. In this paper, the standard analysis of the stabilized Galerkin method on isotropic meshes is extended to more general meshes with boundary layer refinement. Simplicial Lagrangian elements of arbitrary order are used.

Prussian blue (PB) and Prussian blue analogues (PBAs) are compounds with potential applications in a large variety of fields such as gas storage, poison antidotes, electrochromism, electrochemistry and molecular magnets. The compounds are easy to synthesize, cheap, environmentally friendly and have been pursued for both fundamental research and industrial purposes. Despite the multifunctionality of PB and PBAs, they have complicated compositions, which are largely dependent on the synthesis methods and storage conditions. Thus, performing investigations on such compounds with defined composition, stoichiometry and crystal structure is essential. This thesis has focused on synthesis and detailed structure characterization of copper hexacyanoferrate (CuHCF) via X-ray powder diffraction (XRPD), neutron powder diffraction (NPD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), inductively coupled plasma-optical emission spectroscopy (ICP-OES), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Mössbauer spectroscopy, extended X-ray absorption fine structure (EXAFS), infrared (IR) and Raman techniques. In addition, kinetics of thermal dehydration process, CO2 adsorption and CO2 adsorption kinetics were investigated. Moreover, in operando synchrotron X-ray diffraction experiments were performed to gain insight into the structure-electrochemistry relationships in an aqueous CuHCF/Zn battery during operation. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.</p>

This thesis is concerned with the task of autonomous selection of objects to remove (unload) them from a pile in robotic manipulation systems. Applications such as the automation of logistics processes and service robots require an ability to autonomously manipulate objects in the environment. A collapse of a pile of objects due to an inappropriate choice of the object to be removed from the pile cannot be afforded for an autonomous robotic manipulation system. This dissertation presents an indepth analysis of the problem and proposes methods and algorithms to empower robotic manipulation systems to select a safe object from a pile elaborately and autonomously. The contributions presented in this thesis are three-fold. First, a set of algorithms is proposed for extracting a minimal set of high level symbolic relations, namely, gravitational act and support relations, of physical interactions between objects composing a pile. The symbolic relations, extracted by a geometrical reasoning method and a static equilibrium analysis can be readily used by AI paradigms to analyze the stability of a pile and reason about the safest set of objects to be removed. Considering the problem of undetected objects and the uncertainty in the estimated poses as they exist in realistic perception systems, a probabilistic approach is proposed to extract the support relations and to make a probabilistic decision about the set of safest objects using notions from machine learning and decision theory. Second, an efficient search based algorithm is proposed in an internal representation to automatically resolve the inter-penetrations between the shapes of objects due to errors in the poses estimated by an existing object detection module. Refining the poses by resolving the inter-penetrations results in a geometrically consistent model of the environment, and was found to reduce the overall pose error of the objects. This dissertation presents the concept of minimum translation search for object pose refinement and discusses a discrete search paradigm based on the concept of depth of penetration between two polyhedrons. Third, an application centric evaluation of ranging sensors for selecting a set of appropriate sensors for the task of object detection in the design process of a real-world robotics manipulation system is presented. The performance of the proposed algorithms are tested on data sets generated in simulation and from real-world scenarios.

Cette thèse se place dans le contexte de la vérification déductive des programmes et a pour objectif de formaliser un certain nombre de concepts qui sont mis en œuvre dans l'outil de vérification Why3.L'idée générale est d'explorer des solutions qu'une approche à base de systèmes de types peut apporter à la vérification. Nous commençons par nous intéresser à la notion du code fantôme, une technique implantée dans de nombreux outils de vérification modernes, qui consiste à donner à des éléments de la spécification les apparences d'un code opérationnel. L'utilisation correcte du code fantôme requiert maintes précautions puisqu'il ne doit jamais interférer avec le reste du code. Le premier chapitre est consacré à une formalisation du code fantôme, en illustrant comment un système de types avec effets en permet une utilisation à la fois correcte et expressive. Puis nous nous intéressons à la vérification des programmes manipulant des pointeurs. En présence d'aliasing, c'est-à-dire lorsque plusieurs pointeurs manipulés dans un programme dénotent une même case mémoire, la spécification et la vérification deviennent non triviales. Plutôt que de nous diriger vers des approches existantes qui abordent le problème d'aliasing dans toute sa complexité, mais sortent du cadre de la logique de Hoare, nous présentons un système de types avec effets et régions singletons qui permet d'effectuer un contrôle statique des alias avant même de générer les obligations de preuve. Bien que ce système de types nous limite à des pointeurs dont l'identité peut être connue statiquement, notre observation est qu'il convient à une grande majorité des programmes que l'on souhaite vérifier. Enfin, nous abordons les questions liées à la vérification de programmes conçus de façon modulaire. Concrètement, nous nous intéressons à une situation où il existe une barrière d'abstraction entre le code de l'utilisateur et celui des bibliothèques dont il dépend. Cela signifie que les bibliothèques fournissent à l'utilisateur une énumération de fonctions et de structures de données manipulées, sans révéler les détails de leur implémentation. Le code de l'utilisateur ne peut alors exploiter ces données qu'à travers un ensemble de fonctions fournies. Dans une telle situation, la vérification peut elle-même être modulaire. Du côté de l'utilisateur, la vérification ne doit alors s'appuyer que sur des invariants de type et des contrats de fonctions exposés par les bibliothèques. Du côté de ces dernières, la vérification doit garantir que la représentation concrète raffine correctement les entités exposées, c'est-à-dire en préservant les invariants de types et les contrats de fonctions. Dans le troisième chapitre nous explorons comment un système de types permettant le contrôle statique des alias peut être adapté à la vérification modulaire et le raffinement des structures de données. / This thesis is conducted in the framework of deductive software verification.is aims to formalize some concepts that are implemented in the verification tool Why3. The main idea is to explore solutions that a type system based approach can bring to deductive verification. First, we focus our attention on the notion of ghost code, a technique that is used in most of modern verification tools and which consists in giving to some parts of specification the appearance of operational code. Using ghost code correctly requires various precautions since the ghost code must never interfere with the operational code. The first chapter presents a type system with effects illustrating how ghost code can be used in a way which is both correct and expressive. The second chapter addresses some questions related to verification of programs with pointers in the presence of aliasing, i.e. when several pointers handled by a program denote a same memory cell. Rather than moving towards to approaches that address the problem in all its complexity to the costs of abandoning the framework of Hoare logic, we present a type system with effects and singleton regions which resolves a liasing issues by performing a static control of aliases even before the proof obligations are generated. Although our system is limited to pointers whose identity must be known statically, we observe that it fits for most of the code we want to verify. Finally, we focus our attention on a situation where there exists an abstraction barrier between the user's code and the one of the libraries which it depends on. That means that libraries provide the user a set of functions and of data structures, without revealing details of their implementation. When programs are developed in a such modular way, verification must be modular it self. It means that the verification of user's code must take into account only function contracts supplied by libraries while the verification of libraries must ensure that their implementations refine correctly the exposed entities. The third chapter extends the system presented in the previous chapter with these concepts of modularity and data refinement.

Preparation and performance of the perovskite-type barium strontium cobalt iron oxide (Ba_0.5 Sr_0.5 Co_0.8 Fe_0.2 O_(3-δ), BSCF) and its doped compositions were studied in this dissertation. Three transition metals (copper, nickel and niobium) were substituted into the parent BSCF at various ratios to create the formula Ba_0.5 Sr_0.5 (Co_0.8 Fe_0.2)_(1-x) M_x O_(3-δ) (0.02≤x≤0.30; M=Cu,Ni or Nb). Two synthetic methods (solid-state reaction and wet chemical co-precipitation) were developed for the preparation of starting powders. In the previous reports [1, 2], BSCF ceramics suffered from insufficient densification and severe cracking; these problems were resolved in this study by optimising the ceramic processing conditions. The phase transition sequences from starting powders to single-phase cubic perovskite were studied by SEM, XRD, TGA, EDS and Raman spectroscopy. The powders prepared by solid-state method were found to require higher calcination temperature to form pure perovskite phase, and an extra intermediate structure (Ba,Sr)Fe_2 O_4 was detected in the reaction sequence. The materials performance was examined from five aspects: thermal stability, chemical stability, oxygen permeability, electronic conductivity and mechanical performance. The secondary phases of thermal/chemical degradation were investigated, and a needle-like intragranular precipitate was originally discovered in this work. It was discovered that the niobium substitution could significantly improve BSCF’s thermal stability and chemical stability. The oxygen permeability and mechanical performance were also improved by niobium when the substitution ratios are small (< 10%). Although the electronic conductivity was lowered by niobium substitution as a trade-off, it does not become a drawback to restrict the materials’ potential applications as mixed ionic-electronic conductors (MIEC).Furthermore, the material system’s “composition - lattice structure - performance” relationships were systematically investigated in this work; the oxygen deficiency value (δ) and the average bond energy (ABE) were found to have strong correlations with the materials performance.

The need to produce lighter components due to environmental aspects and the development of electrical vehicles represents an opportunity for cast aluminium-silicon alloys. With high specific strength, good castability, high corrosion resistance and recyclability, these alloys offer an attractive combination of properties as an alternative to steel, cast iron and titanium-based components in certain applications. To take advantage of such a combination of properties, there is a need to ensure that they can be reliably achieved. In other words, high performing components need to be produced. For that, the production cycle, from alloy selection and melt preparation, to the casting and heat treatment of the component must be understood and controlled as a whole. The different steps in the production cycle will affect the microstructure of the components and hence the resulting mechanical properties. Understanding the relation between the different steps in the production cycle, its consequences on the microstructural features and on the mechanical properties constitutes the aim of this thesis. Experiments applying state-of-the-art knowledge regarding effect of casting process, alloying system and post-process variables were performed aimed at achieving properties similar to those of high pressure die casting (HPDC) components. Different melt quality determination tools were evaluated on three different EN AC-46000 melt qualities. The influence of modification, grain refinement and both treatments together was assessed on an Al-10Si alloy solidified under different cooling rates. The tensile behaviour and the impact of features such as secondary dendrite arm spacing (SDAS) or grain sizes was quantified. It was corroborated that by appropriate selection and control of such alloying system, process and post-process variables it is possible to achieve HPDC EN AC-46000 tensile and fatigue properties through a T5 treated sand cast EN AC-42100 alloy. On the other hand, the available techniques for melt quality assessment are inadequate, requiring further analysis to successfully identify the melt quality. Additionally, it was observed that decreasing the melt quality by additions of 25 wt.% of machining chips did not significantly decrease the tensile properties but slightly increased the variation in them. In relation to the modification and grain refinement of Al-10Si alloys it was concluded that with the slowest cooling rate tested, additions of only grain refiner did not successfully produce equiaxed grains. For cooling rates corresponding to dendrite arm spacings of 15 μm and slower, combined additions of grain refiner and modifier can lead to higher tensile properties compared to the corresponding separate additions. SDAS was observed to describe flow stress through the Hall-Petch equation but grain size did not show a physically meaningful relationship. Furthermore, beginning of cracking was detected in the plastic deformation region at dendrite/eutectic boundaries and propagated in a trans-granular fashion.

L'utilisation croissante de véhicules au cours des dernières décennies a causé une augmentation dans les émissions de gaz d'échappement nocifs provoquant des problèmes de santé et d'environnement. Cette problématique a conduit les gouvernements à mettre en place des limites d'émissions plus strictes. Afin de respecter ces limites, il est nécessaire de développer des systèmes de post-traitement plus performants. Parmi plusieurs solutions possibles, l'analyse et l'optimisation de l'impact de l'écoulement sur les réactions chimiques est une approche importante pour résoudre ce problème complexe. Au point de vue expérimental, il est très difficile de mesurer le champ de vitesse détaillé et la distribution de la température et de la concentration. Les simulations numériques peuvent fournir des informations supplémentaires pour comprendre l'interaction entre la distribution de l'écoulement et l'efficacité des réactions. La simulation numérique de ces systèmes est très coûteuse due aux phénomènes physiques et chimiques complexes ayant lieu simultanément dans tout le système. Afin de diminuer ce coût, on peut développer des modèles physiques et chimiques simplifiés ainsi que des techniques numériques spécifiques pour simuler le système tout en réduisant le temps de calcul. Dans cette thèse, nous développons une approche générale pour modéliser et simuler le système de post-traitement des gaz d'échappement automobile contenant les aspects physiques et chimiques. L'approche présente combine des modèles simplifiés et des techniques numériques de multi-résolutions afin de capturer correctement les caractéristiques de l'écoulement dans le système. Alors que la méthode de raffinement de maillage adaptatif (AMR) est optimisée afin de minimiser l'effort de calcul dans les régions divergente et convergente, un modèle de sous-maille est développé pour décrire l'écoulement dans les micro-canaux du substrat catalytique placé entre la région divergente et la région convergente. La performance du modèle est validée par rapport aux résultats expérimentaux obtenus par Benjamin et al. (2002). Le couplage effectif de méthode AMR et le modèle de sous-maille permet de capturer les caractéristiques de l'écoulement dans le système avec un temps de calcul réduit de manière significative. L'impact de l'écoulement pulsé et de l'écoulement en expansion sur le taux de réaction dans un canal de monolithe est étudié numériquement. La méthode AMR est montrée pour capturer les couches mince de diffusion près de la paroi à l'interface solide-liquide. Sur la base des résultats numériques, nous proposons un modèle simplifié de transport capturant les effets de l'écoulement, la diffusion et la réaction catalytiques à la paroi. Le modèle simplifié de transport peut être directement appliqué dans la forme de modèle de sous-maille pour la description complète de tous les processus physiques et chimiques ayant lieu à l'intérieur du système. Grâce aux approches de modélisation numériques physiques et chimiques développées, il est possible de simuler le système en trois dimensions avec un temps de calcul raisonnable capturant encore la physique principale du problème. / The increasing use of passenger vehicles over the past decades has caused an increase in harmful exhaust gas emissions which give rise to environmental and health problems. This problematic has led governments to establish very stringent emission limits. The emission restrictions require more performing after-treatment systems. Among many other solutions, analysing and optimising the flow impact on the conversion efficiency is an important step towards the solution of the complex engineering problem. Detailed velocity, temperature and concentration distributions are very difficult to measure experimentally. Numerical simulations can provide additional information to understand the interaction of flow distribution and conversion efficiency. The simulation of these systems is computationally very expensive due to complex physical and chemical phenomena occurring simultaneously throughout the system. To overcome this cost, one can resort to some simplified physical and chemical models together with specific numerical techniques to simulate the system with a reduced computational time. In this dissertation, we develop a general approach to model and simulate the automotive catalytic converter system including all the physical and chemical processes. The present approach combines sub-grid models and numerical multi-resolution techniques in order to correctly capture the flow characteristics inside an automotive catalytic converter. While Adaptive Mesh Refinement (AMR) techniques are optimized in order to minimise the computational effort in the divergent and convergent regions, a sub-grid model is developed to describe the flow inside the catalytic substrate placed between the convergent and divergent regions. The performance of the sub-grid model is validated against the experimental results obtained by Benjamin et al. (2002). The effective coupling of AMR techniques and the sub-grid model allows to capture the flow features with significantly reduced computational time. The impact of pulsating and expansion flow on the conversion efficiency within a single monolith channel is investigated numerically. AMR techniques are shown to capture the small boundary layers near the wall at the solid-fluid interface. Based on the numerical results, we propose a simplified transport model that captures the effects of flow, diffusion and catalytic wall reactions. The simplified transport model can be directly applied as a sub-grid model for the complete description of all the physical and chemical processes taking place inside the system. The developed physical, chemical and numerical modelling approaches make the three-dimensional simulations possible with a reasonable computational time still capturing the main physics of the problem.

Dans cette thèse, nous présentons des approches d’adaptation d’un processus d’alignement aux caractéristiques des ontologies alignées, qu'il s'agisse de caractéristiques quantitatives telles que leur volume ou de caractéristiques particulières liées par exemple à la façon dont les labels des concepts sont construits. Concernant les caractéristiques quantitatives, nous proposons deux méthodes de partitionnement d'ontologies qui permettent l’alignement des ontologies très volumineuses. Ces deux méthodes génèrent, en entrée du processus d'alignement, des sous ensembles de taille raisonnable des deux ontologies à aligner en prenant en compte dès le départ l'objectif d'alignement dans le processus de partitionnement.Concernant les caractéristiques particulières des ontologies alignées, nous présentons l’environnement TaxoMap Framework qui permet la spécification de traitements de raffinement à partir de primitives prédéfinies. Nous proposons un langage de patrons MPL (the Mapping Pattern Language) que nous utilisons pour spécifier les traitements de raffinement.En plus des approches d’adaptation aux caractéristiques des ontologies alignées, nous présentons des approches de réutilisation des résultats d'alignement pour l'ingénierie ontologique. Nous nous focalisons plus particulièrement sur l'utilisation de l'alignement pour l'enrichissement d'ontologies. Nous étudions l'apport des techniques d'alignement pour l'enrichissement et l'impact des caractéristiques de la ressource externe utilisée comme source d'enrichissement. Enfin, nous présentons la façon dont l'environnement TaxoMap Framework a été implémenté et les expérimentations réalisées : des tests sur le module d'alignement TaxoMap, sur l'approche de raffinement de mappings, sur les méthodes de partitionnement d'ontologies de très grande taille et sur l'approche d'enrichissement d'ontologies. / In this thesis, we present approaches for adapting an alignment process to the characteristics of the aligned ontologies, whether in respect of the quantitative characteristics such as their volume or the particular characteristics related for example to the way in which the labels of the concepts are built.Concerning the quantitative characteristics, we propose two ontology partitioning methods that make the alignment of very large ontologies possible. Both methods generate in the input of the alignment process, subsets of reasonable size of the two ontologies to be aligned by taking into account, as soon as possible, the alignment objective in the partitioning process.Concerning the particular characteristics of the aligned ontologies, we present the TaxoMap Framework environment that allows the specification of refinement treatments from predefined primitives. We propose a pattern language MPL (the Mapping Pattern Language) that we use to specify the refinement treatments.In addition to the adaptation approaches to the characteristics of the aligned ontologies, we present approaches for re-using the alignment results for the ontological engineering. We focus specifically on the use of the alignment for the ontology enrichment. We study the contribution of the alignment techniques for the enrichment and the impact of the characteristics of the external resource used as a source of enrichment.Finally, we present how the TaxoMap Framework environment was implemented and the performed experiments: tests on the TaxoMap alignment module, on the mappings refinement approach, on the partitioning methods of very large ontologies and on the ontology enrichment approach.

Orientador: Claudia Longo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-18T16:06:49Z (GMT). No. of bitstreams: 1 Santos_ReginaldodaSilva_D.pdf: 4843119 bytes, checksum: 3b7dd1f72628c75da40e0f76317b6cfa (MD5) Previous issue date: 2011 / Resumo: Nanopartículas de TiO2 foram preparadas por método sol-gel a partir da hidrólise de isopropóxido de titânio, tratamento hidrotérmico (200 °C, 8 h) e calcinação (450 °C, 30 min); amostras de TiO2 dopado com ferro (Fe:TiO2) foram obtidas pela mesma metodologia incluindo nitrato férrico nos precursores (razão molar Fe/Ti de 1, 3 e 5%). Para comparação, investigou-se também uma mistura de a-Fe2O3/TiO2 (Fe/Ti = 4 %). O intervalo de banda proibida, de 3,2 eV para o TiO2, diminuiu de 3,0 para 2,7 eV com o aumento do teor de Fe. Análises por difração de raios X e refinamento Rietveld revelaram que o TiO2 é constituído por anatasa (82 %) e brookita (18 %); para Fe:TiO2, observou-se 30 % de brookita e identificou-se 0,5; 1,0 e 1,2 wt % de hematita nas amostras com Fe/Ti de 1; 3 e 5%. Filmes porosos, com espessura de 1,5 mm, foram depositados em eletrodos de vidro a partir de suspensões com polietilenoglicol e calcinação. Em solução aquosa, irradiados com um simulador solar, os eletrodos apresentaram comportamento de semicondutor tipo-n: para o TiO2, fotopotencial de -0,95 V em circuito aberto e fotocorrente de 0,34 mA cm em 0,8 V; valores muito menores foram observados para Fe:TiO2 e a-Fe2O3/TiO2. O TiO2 também apresentou maior atividade fotocatalítica para degradação de fenol e, quando utilizado como foto-anodo em célula de dois compartimentos, polarizado a + 0,7 V por 4 h, promoveu a oxidação de formiato e a produção de 18 mmol de H2 sobre contra-eletrodo de Pt. Os eletrodos de Fe:TiO2 e a-Fe2O3/TiO2 apresentaram valores menores de corrente, impossibilitando a obtenção de H2 no catodo. Embora as amostras de Fe:TiO2 tenham apresentado maior aproveitamento da luz visível, a inserção do ferro como dopante e a hematita segregada podem dificultar a separação das cargas fotogeradas e o transporte de elétrons através dos contornos de grãos, resultando em menor atividade fotocatalítica nas aplicações decorrentes da conversão de energia solar / Abstract: TiO2 nanoparticles were synthesized by sol-gel method from hydrolysis of titanium isopropoxide followed by hydrothermal treatment (200 °C, 8 h) and annealing (450 °C, 30 min). Fe doped TiO2 (Fe:TiO2) samples were synthesized by similar methodology adding ferric nitrate, with Fe/Ti atomic ratio corresponding to 1, 3 and 5 %. A mixture of a-Fe2O3/TiO2 (with Fe/Ti = 4 at %) was also investigated. The band gap energy, estimated as 3.2 eV for TiO2, gradually ranged from 3.0 to 2.7 eV with increasing iron content. Rietveld refinement of X ray diffraction data revealed that TiO2 consisted of 82 % anatase and 18 % brookite; for Fe:TiO2, brookite increased to 30 % and hematite was also identified (0.5; 1.0 and 1.2 wt % for samples prepared with 1; 3 and 5 % of Fe/Ti). Porous films, 1.5 mm thick, were deposited on transparent electrodes from aqueous suspension with polyethylene glycol and annealing. In aqueous solution, irradiated by a solar simulator, the electrodes exhibited n-type semiconductor behavior: for TiO2 electrode, -0,95 V of photo-potential at open circuit condition and 0,34 mA cm of photocurrent when biased at 0.8 V; much lower values were observed for Fe:TiO2 and a-Fe2O3/TiO2 electrodes. TiO2 film also exhibited higher photocatalytic activity for phenol oxidation than other samples. The electrodes were also used as photo-anodes in a two-compartment electrochemical cell with Pt counter-electrode and HCOONa as hole scavenger. The cell assembled with irradiated TiO2 anode biased at + 0.7 V for 4 h produced 18 mmol of H2 at the cathodic compartment. H2 evolution was not detected and very low currents were observed for Fe:TiO2 or a-Fe2O3/TiO2 photo- anodes. Although Fe:TiO2 samples exhibited higher sunlight harvesting, inserted iron and segregated hematite can hinder the separation of photogenerated charges, as well as the electron transport across the grain boundaries, resulting in lower photocatalytic activity for solar energy conversion / Doutorado / Físico-Química / Doutor em Ciências