Sintesi e caratterizzazione di CaCu3Ti4O12 (CCTO) per applicazioni in fotoelettrocatalisi

A promising strategy to mitigate both the energy crisis and global warming is the development of solar fuels and chemicals using as feedstock CO2 in combination with simple molecules such as water. This process stores the solar energy into chemical bonds, leading to a carbon-neutral approach of fuels and chemicals production. Aim of this thesis was the synthesis and characterization of CaCu3Ti4O12 (CCTO)- based compounds to be used as visible light photocatalyst for CO2 to chemical conversion. Different compositions were produced doping CCTO with increasing concentration of iron into the perovskite’s A site in order to identify the materials with the highest photo- and photoelectrocatalytic properties. The most promising compositions were used to produce photoelectrodes by screen printing that were characterized by linear and cyclic voltammetry, impedance spectroscopy and Mott-Schottky analysis to evaluate the electrical conductivity and calculate the flat band potential and the number of charge carriers in the samples. The photoelectrodes were then tested in a photoelectrochemical (PEC) cell for the conversion of CO2 into fuel and chemicals. The results obtained confirm that CCTO-based materials can be considered promising materials for carbon dioxide photo-electrochemical reduction.

Relative influence of gaze and static arm position in the Superior Parietal Lobule of the macaque monkey during reaching

The superior parietal lobule (SPL) of macaques is classically described as an associative cortex implicated in visuospatial perception, planning and control of reaching and grasping movements (De Vitis et al., 2019; Galletti et al., 2003, 2018, 2022; Fattori et al., 2017; Hadjidimitrakis et al., 2015). These processes are the result of the integration of signals related to different sensory modalities. During a goal-directed action, eye and limb information are combined to ensure that the hand is transported at the gazed target location and the arm is maintained steady in the final position. The SPL areas V6A, PEc and PE contain cells sensitive to the direction of gaze and limb position but less is known about the degree of independent encoding of these signals. In this thesis, we evaluated the influence of eye and arm position information upon single neuron activity of areas V6A, PEc and PE during the holding period after the execution of arm reaching movement, when the gaze and hand are both still at the reach target. Two male macaques (Macaca fascicularis) performed a reaching task while single unit activity was recorded from areas V6A, PEc and PE. We found that neurons in all these areas were modulated by eye and static arm positions with a joint encoding of gaze and somatosensory signals in V6A and PEc and a mostly separate processing of the two signals in PE. The elaboration of this information reflects the functional gradient found in the SPL with the caudal sector characterized by visuo-somatic properties in comparison to the rostral sector dominated by somatosensory signals. This evidence well agree also with the recent reallocation of areas V6A and PEc in Brodmann’s area 7 depending on their similar structural and functional features with respect to PE belonging to Brodmann’s area 5 (Gamberini et al., 2020).

Kinetics of photogenerated carriers in nanostructured semiconductor heterojunctions for solar water splitting

This thesis aims to investigate the fundamental processes governing the performance of different types of photoelectrodes used in photoelectrochemical (PEC) applications, such as unbiased water splitting for hydrogen production. Unraveling the transport and recombination phenomena in nanostructured and surface-modified heterojunctions at a semiconductor/electrolyte interface is not trivial. To approach this task, the work presented here first focus on a hydrogen-terminated p-silicon photocathode in acetonitrile, considered as a standard reference for PEC studies. Steady-state and time-resolved excitation at long wavelength provided clear evidence of the formation of an inversion layer and revealed that the most optimal photovoltage and the longest electron-hole pair lifetime occurs when the reduction potential for the species in solution lies within the unfilled conduction band states. Understanding more complex systems is not as straight-forward and a complete characterization that combine time- and frequency-resolved techniques is needed. Intensity modulated photocurrent spectroscopy and transient absorption spectroscopy are used here on WO3/BiVO4 heterojunctions. By selectively probing the two layers of the heterojunction, the occurrence of interfacial recombination was identified. Then, the addition of Co-Fe based overlayers resulted in passivation of surface states and charge storage at the overlayer active sites, providing higher charge separation efficiency and suppression of recombination in time scales that go from picoseconds to seconds. Finally, the charge carrier kinetics of several different Cu(In,Ga)Se2 (CIGS)-based architectures used for water reduction was investigated. The efficiency of a CIGS photocathode is severely limited by charge transfer at the electrode/electrolyte interface compared to the same absorber layer used as a photovoltaic cell. A NiMo binary alloy deposited on the photocathode surface showed a remarkable enhancement in the transfer rate of electrons in solution. An external CIGS photovoltaic module assisting a NiMo dark cathode displayed optimal absorption and charge separation properties and a highly performing interface with the solution.

Caratterizzazione ottica e fotoelettrochimica di fotoanodi di triossido di tungsteno e bismuto vanadato (WO3/BiVO4) con catalizzatore (CoFe-PB)

Il presente lavoro di tesi si propone di illustrare il meccanismo di funzionamento delle celle fotoelettrochimiche (PEC cell) per la produzione di idrogeno, grazie allo studio di diversi semiconduttori, attraverso il cosiddetto fenomeno del water splitting. Nella cella `e stata testata un’eterogiunzione di Triossido di Tungsteno (WO3), una di Triossido di Tungsteno e Bismuto Vanadato (BiVO4) e una terza analoga alla precedente con l’aggiunta di un catalizzatore (CoFe–PB, cobalto-ferro blu di Prussia) per diminuire l’effetto della ricombinazione delle coppie elettrone - lacuna. All’interno della cella il campione era immerso in una soluzione di Acetato (CH3 COO – ) 0.2 M a pH 5. Le principali grandezze misurate sono la fotocorrente prodotta all’interno della cella e il tasso di riduzione e ossidazione dell’acqua.

Fabrication by magnetron sputtering and characterization of electrodes based on CuIn0.7Ga0.3Se2 (CIGS)

This thesis work aims to produce and test multilayer electrodes for their use as photocathode in a PEC device. The electrode developed is based on CIGS, a I-III-VI2 semiconductor material composed of copper (Cu), indium (In), Gallium (Ga) and selenium (Se). It has a bandgap in the range of 1.0-2.4 eV and an absorption coefficient of about 105cm−1, which makes it a promising photocathode for PEC water splitting. The idea of our multilayer electrode is to deposit a thin layer of CdS on top of CIGS to form a solid-state p–n junction and lead to more efficient charge separation. In addition another thin layer of AZO (Aluminum doped zinc oxide) is deposit on top of CdS since it would form a better alignment between the AZO/CdS/CIGS interfaces, which would help to drive the charge transport further and minimize charge recombination. Finally, a TiO2 layer on top of the electrodes is used as protective layer during the H2 evolution. FTO (Fluorine doped tin oxide) and Molybdenum are used as back-contact. We used the technique of RF magnetron sputtering to deposit the thin layers of material. The structural characterization performed by XDR measurement confirm a polycrystalline chalcopyrite structural with a preferential orientation along the (112) direction for the CIGS. From linear fit of the Tauc plot, we get an energy gap of about 1.16 eV. In addition, from a four points measurements, we get a resistivity of 0.26 Ωcm. We performed an electrochemical characterization in cell of our electrodes. The results show that our samples have a good stability but produce a photocurrent of the order of μA, three orders of magnitude smaller than our targets. The EIS analysis confirm a significant depletion of the species in front of the electrode causing a lower conversion of the species and less current flows.

Cadastro domiciliar

Apresenta a ficha de cadastro domiciliar, seu passo a passo e peculiaridades no preenchimento. A ficha tem como objetivo geral de fazer o cadastramento da família, funcionando como um mecanismo de levantamento populacional e a verificação da abrangência das equipes de saúde.

Sistema e-SUS/Atenção Básica

Recurso aborda o Sistema e-SUS/AB, história, proposta, estrutura e implementação. Apresenta suas versões e características até o presente momento e os sistemas que fazem parte do e-SUS/AB. Aborda o preenchimentos das fichas e elementos do cadastro tanto de pessoas quanto localidades e famílias (cadastro individual e cadastro domiciliar), apresenta também as fichas de atendimento odontológico, de atividades coletiva e de visita domiciliar, todas essas sendo recursos do e-SUS/AB. Apresenta passo a passo de como instalar o sistema e por fim, relata a experiência de implantação do sistema concluída em SC e segue para a resposta de perguntas realizadas durante a videoaula online.

Ficha de visita domiciliar

Aborda a Ficha de visita domiciliar do e-SUS realizadas pelo agente comunitário de saúde. Sensibiliza sobre a adoção do registro no SISAB/e-SUS, apresenta a diferença entre visita domiciliar e e atendimento no domicílio, apresenta a estrutura e última verão da Ficha, bem como esclarece pontos importantes sobre o preenchimento.

Ficha de procedimentos

Aborda a Coleta de dados simplificada (CDS) e as fichas que a compõem, aborda mais especificamente a Ficha de procedimentos, seus campos, preenchimento e orientações gerais.

Ficha de atividade coletiva

Apresenta a Ficha de atividade coletiva do e-SUS, versão 1.3.0, que faz parte da Coleta de dados simplificada (CDS). Tem como objetivo ser o formulário das atividades realizadas pela equipe de saúde conforme as necessidades do território. Apresenta aspectos gerais da ficha, campos, composição, observações, etc.

Ficha de atendimento individual

Aborda a Ficha de Atendimento Individual, seu propósito de coletar dados dos atendimentos realizados em cada turno, preenchimento em cada bloco e campos, especificidades, e orientações gerais.

Ficha de atendimento odontológico individual

Aborda a Ficha de atendimento odontológica individual do e-SUS, que compõe a Coleta de Dados Simplificada (CDS) do SUS. Apresenta a estrutura, os blocos e especificações do preenchimento bem como os profissionais que podem preenchê-la.

Experiência de Barra Velha com o e-SUS

Aborda a implementação do e-SUS no no município de Barra Velha em outubro de 2013, o processo de treinamento e adesão dos profissionais da Unidade Básica de Saúde, os resultados e relatórios de cada etapa de implementação. Apresenta também o sistema e como se dá o suporte e manutenção, os erros ocorridos durante a implementação e como evitá-los.

Cadastro individual

Aborda o cadastro individual do sistema e-SUS, que objetiva captar as informações sobre os usuários adscritos no território de equipe de AB, visando identificar as características sociodemográficas, problemas e condições de saúde dos usuários no território das equipes de atenção básica. Apresenta a estrutura da ficha, informações gerais e de controle, especificações etc.

Apresentação geral do e-SUS Atenção Básica

Apresenta questões gerais sobre o e-SUS, surgimento, origem e constituição. Aborda um histórico do sistema desde 1998, com o antigo SIAB, e a posterior demanda e surgimento do e-SUS. Apresenta as divisões e componentes e integrantes do sistema, bem como novidades, suas bases legais e outras características básicas.