Aline Pascon

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Papers by Aline Pascon

Electrochemical Behavior of Symmetric Electrical Double-Layer Capacitors and Pseudocapacitors and Identification of Transport Anomalies in the Interconnected Ionic and Electronic Phases Using the Impedance Technique

by Aline Pascon and Willian Nunes

Nanomaterials

A double-channel transmission line impedance model was applied to the study of supercapacitors to... more A double-channel transmission line impedance model was applied to the study of supercapacitors to investigate the charge transport characteristics in the ionic and electronic conductors forming the electrode/solution interface. The macro homogeneous description of two closely mixed phases (Paasch–Micka–Gersdorf model) was applied to study the influence of disordered materials on the charge transport anomalies during the interfacial charge–discharge process. Different ex situ techniques were used to characterize the electrode materials used in electrical double-layer (EDLC) and pseudocapacitor (PC) devices. Two time constants in the impedance model were adequate to represent the charge transport in the different phases. The interfacial impedance considering frequency dispersion and blocked charge transfer conditions adequately described the charge storage at the interface. Deviations from the normal (Fickian) transport involving the ionic and electronic charge carriers were identifie...

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Effect of conductivity, viscosity, and density of water-in-salt electrolytes on the electrochemical behavior of supercapacitors: molecular dynamics simulations and in situ characterization studies

Materials Advances, 2022

Molecular configurations of the 1.0 mol dm−3 and 8.0 mol dm−3 NaClO4 aqueous electrolytes, and sh... more

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Comparasion between TiO2 thin films deposited by DC and RF sputtering

2019 34th Symposium on Microelectronics Technology and Devices (SBMicro), 2019

This paper compares titanium oxide (TiO2) thin films deposited by RF and DC sputtering. Structura... more This paper compares titanium oxide (TiO2) thin films deposited by RF and DC sputtering. Structural characterization was used to investigate the morphology of TiO2 thin films. Both films show the rutile and anatase crystal structure; ellipsometry show thickness and refractive index of 50 nm and 2.43 for the TiO2 deposited by DC sputtering and 40 nm and 2.32 for the film by RF sputtering; AFM shows the roots mean square (RMS) roughness of 6.5 nm and 8 nm for TiO2 deposited by DC and RF sputtering, respectively. For electrical characterization was developed MOS capacitor; from them was possible to determine which method forms the best dielectric film, defined by high dielectric constant value (high-k), lower charge density (Q0/q) and flat-band voltage (VFB) around -0.9V. Therefore, the best method to deposit TiO2 is DC reactive sputtering; because this method showed a better electrical conditions and a well-defined crystalline structure

Field Effect Transistors based on Graphene Micro Wires Defined by Lithography and Plasma Etching

2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro), 2018

In this work, Field Effect Transistors based on Graphene (GraFETs) were fabricated, with the curr... more In this work, Field Effect Transistors based on Graphene (GraFETs) were fabricated, with the current conduction channel with 10 wires (width of 0.36 $\mu$ m each) in parallel, using the process steps of lithography and oxygen plasma etching. Furthermore, alternatives films, such as TiOx, as gate dielectric, and TiN, as metal electrodes, were used in these devices. Raman spectroscopy, used to identify the integrity of the Chemical Vapor Deposition (CVD) graphene layer during the fabrication, indicated that the graphene channel is formed by monolayer structure with high quality, which are important characteristics to get GraFET devices. SEM analyses, used to identify the device surfaces, indicated that it is possible to obtain the GraFET channel with 10 graphene wires in parallel. To finalize, all current-voltage curves indicated that GraFETs are working and our fabrication method can be used in device and circuit technology based on graphene.

Modular Label-Free Electrochemical Biosensor Loading Nature-Inspired Peptide toward the Widespread Use of COVID-19 Antibody Tests

ACS Nano

Limitations of the recognition elements in terms of synthesis, cost, availability, and stability ... more Limitations of the recognition elements in terms of synthesis, cost, availability, and stability have impaired the translation of biosensors into practical use. Inspired by nature to mimic the molecular recognition of the anti-SARS-CoV-2 S protein antibody (Ab S) by the S protein binding site, we synthesized the peptide sequence of Asn-Asn-Ala-Thr-Asn-COOH (abbreviated as PEP2003) to create COVID-19 screening label-free (LF) biosensors based on a carbon electrode, gold nanoparticles (AuNPs), and electrochemical impedance spectroscopy. The PEP2003 is easily obtained by chemical synthesis, and it can be adsorbed on electrodes while maintaining its ability for Ab S recognition, further leading to a sensitivity 3.4-fold higher than the full-length S protein, which is in agreement with the increase in the target-to-receptor size ratio. Peptide-loaded LF devices based on noncovalent immobilization were developed by affording fast and simple analyses, along with a modular functionalization. From studies by molecular docking, the peptide−Ab S binding was found to be driven by hydrogen bonds and hydrophobic interactions. Moreover, the peptide is not amenable to denaturation, thus addressing the trade-off between scalability, cost, and robustness. The biosensor preserves 95.1% of the initial signal for 20 days when stored dry at 4°C. With the aid of two simple equations fitted by machine learning (ML), the method was able to make the COVID-19 screening of 39 biological samples into healthy and infected groups with 100.0% accuracy. By taking advantage of peptide-related merits combined with advances in surface chemistry and ML-aided accuracy, this platform is promising to bring COVID-19 biosensors into mainstream use toward straightforward, fast, and accurate analyses at the point of care, with social and economic impacts being achieved.

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In Situ Nanocoating on Porous Pyrolyzed Paper Enables Antibiofouling and Sensitive Electrochemical Analyses in Biological Fluids

Combined Density Functional Theory and Molecular Dynamics Simulations To Investigate the Effects of Quantum and Double-Layer Capacitances in Functionalized Graphene as the Electrode Material of Aqueous-Based Supercapacitors

Journal of Physical Chemistry C, 2021

We report on DFT and MD simulations to investigate the contributions of quantum and double-layer ... more

Definition of CVD Graphene Micro Ribbons with Lithography and Oxygen Plasma Ashing

Carbon Trends, 2021

This work presents the definition of CVD (Chemical Vapor Deposition) Graphene Micro Ribbons (GMRs... more This work presents the definition of CVD (Chemical Vapor Deposition) Graphene Micro Ribbons (GMRs) with traditional Photolithography and Oxygen Plasma Ashing, where: (i) CVD Graphene Micro Ribbons were defined in parallel and serpentine patterns; (ii) The defined width dimensions of GMRs are between 0.23 µm and 10 µm; (iii) The empirical calibration curve between physical and mask widths of GMRs was obtained; (iv) With our method, Graphene Field-Effect Transistors, GFETs, can be fabricated with parallel GMRs as conduction channel between source and drain. It is important to notice that parallel channels are used in Silicon Nano Wires 3D Transistors, such as FinFETs. Our method is based on low-cost lithography, compared to commonly found in the literature, based on the definition of graphene patterns by Electron Beam Lithography (high cost and low repeatability techniques). Also, graphene's good quality characteristics remain after GMRs fabrication, as proven by Raman spectroscop...

Desenvolvimento de transistores de efeito de campo baseados em eletrodos de Nitreto de Tântalo e em canais de Grafeno transferidos por dieletroforese (DEF) ou por litografia e corrosão seca

O objetivo deste trabalho e o desenvolvimento de transistores de efeito de campo (Field Effect Tr... more O objetivo deste trabalho e o desenvolvimento de transistores de efeito de campo (Field Effect Transistors - FETs) baseados em grafeno (GraFETs), como canal de conducao eletrica, e em nitreto de tântalo (TaN), como eletrodos de fonte e dreno (S/D). Os transistores sao do tipo back-gate, em que a estrutura de porta e conectada pelo substrato de Si n+ (que e usado como eletrodo), que esta coberto pelo dieletrico de oxido de tântalo (TaOx), que por sua vez, esta em contato com o canal de grafeno. Para obter os GraFETs, folhas de grafeno, dispersas em solucao liquida N-N-dimetilformamida (DMF) ou N-Methyl-2-pyrrolidone (NMP), ou obtidas por deposicao quimica da fase vapor (Chemical Vapor Deposition - CVD), foram depositadas entre S/D a partir de dois processos distintos, respectivamente: i) por dieletroforese (DEP) de folhas dispersas em solucao DMF ou NMP; ou ii) por transferencia das folhas obtidas por CVD sobre as amostras, com etapas sequenciais de litografia optica, de corrosao seca por plasma de oxigenio e de limpeza orgânica. Assim, os dispositivos sao identificados como GraFETs baseados em grafeno DEP ou em grafeno CVD, respectivamente, e sao obtidos individualmente e integrados em arranjo paralelo de 300 transistores. A integracao em escala de centenas de transistores, usando litografia optica e uma primeira inovacao desta tese, pois os principais laboratorios empregam a litografia por feixe de eletrons, o que torna o processo mais lento. Os eletrodos de S/D de TaN, depositados por pulverizacao catodica (sputtering), foram escolhidos pois sao refratarios, o que permite executar etapas de recozimento termico em temperaturas maiores que 400oC, e apresentam funcao trabalho similar a do grafeno, possivelmente resultando em baixo valor da barreira de potencial (menor que 1 eV) na juncao TaN/grafeno. Ambas as caracteristicas permitem reduzir a resistencia de contato entre eletrodo de TaN e grafeno, o que e primordial para o bom desempenho dos GraFETs. Trata-se de outra importante inovacao deste trabalho, pois normalmente os eletrodos sao de Au ou Pt. Assim, calculos ab initio, utilizando teoria da densidade funcional (DFT), foram realizados para investigar as propriedades mecânicas e eletronicas da interface grafeno/TaN a nivel atomico. Dois modelos foram considerados, com terminacoes Ta e N para o ?-TaN(111) com uma, duas, tres e quatro camadas de grafeno sobre a superficie do metal. Nos dois casos, as energias de adesao de 1,8 J/m2 e 0,9 J/m2 para as terminacoes em N e Ta, respectivamente, indicaram aderencia do metal ao grafeno. As funcoes trabalho para ambas as terminacoes foram calculadas, 6,02 eV e 4,8 eV para as terminacoes N e Ta, respectivamente, com apenas esta ultima concordando com valores medidos experimentalmente. Calculos de interface mostraram que o metal com terminacao em Ta e mais transparente a injecao de portadores na interface com o grafeno, uma vez que, nesse caso, nao ha barreira potencial entre o metal e a primeira camada de grafeno. Comportamento este que nao ocorre para a terminacao em N, que possui barreira potencial calculada de 2,4 eV. Assim, a terminacao em Ta e a mais desejada na interface TaN/grafeno, que resulta em menor resistencia de contato, permitindo o funcionamento mais eficiente dos dispositivos. Caracteristicas eletricas de corrente-tensao (I-V) com comportamento ohmico (linear) que indica a ausencia de uma barreira potencial mostram que os transistores funcionam como esperado, indicando que a interface e rica em Ta nos contatos de S/D. Elas mostram tambem que os GraFETs com grafenos DEP e CVD alcancaram transcondutâncias maximas de 2,4 mS e 2,5 mS e minima resistencia de contato de 3,4 ? e 4,3 k?, respectivamente. No entanto, os GraFETs fabricados com grafeno DEP apresentaram alto desvio padrao nas medidas eletricas quando comparadas as medidas eletricas dos GraFETs com grafeno CVD. Caracteristicas fisicas dos GraFETs, baseadas em analises de microscopia eletronica por varredura (SEM) e por espectroscopia Raman, indicaram a obtencao e a integracao dos dispositivos, e que o grafeno CVD apresentou melhor qualidade estrutural que o DEP, alem de uma melhor uniformidade na transferencia das folhas sobre os transistores. Isto permite uma maior integracao dos FETs. Vale salientar que os resultados das caracteristicas fisicas sao consistentes com as eletricas. Assim, concluiu-se que os transistores baseados em canais de conducao eletrica de grafenos CVD e em eletrodos de TaN sao promissores para futuros circuitos integrados em substituicao aos tradicionais baseados em canais de conducao eletrica de Si. Abstract

Anisotropia de larga escala em raios cósmicos de altíssima energia no Observatório Pierre Auger

Foi aplicado o metodo de reconstrucao de uma anisotropia de raios cosmicos para certo numero de d... more Foi aplicado o metodo de reconstrucao de uma anisotropia de raios cosmicos para certo numero de direcoes simuladas, a partir de uma distribuicao consistindo de modulacao dipolar sobreposta a um fluxo isotropico. Usou-se o metodo proposto por J. Aublin e E. Parizot, que permite reconstruir a amplitude e orientcao do dipolo no espaco 3D para um observatorio que possui apenas uma visao parcial do ceu, como e o caso do Observatorio Pierre Auger Sul. Admitiu-se que a exposicao do observatorio para uma dada direcao depende apenas da declinacao, sendo independente da ascensao reta. A modulacao dipolar foi considerada apontando na direcao do centro galactico e levou-se em conta o efeito do erro experimental na determinacao da direcao fazendo-a utuar segundo uma distribuicao gaussiana de meia largura igual ao erro experimental do detector (1,5o). Estudou-se a capacidade de reconstrucao deste dipolo, em direcao e amplitude, para as condicoes do Observatorio Pierre Auger, para varios valores de amplitude do dipolo e varios numeros de eventos, e foram obtidos os limites de tempo observacional necessarios para deteccao em cada caso, para um fluxo de eventos com energias acima de 10 18,5 eV . Por fim, calculou-se o numero de eventos e o tempo necessario de observacao para detectar uma anisotropia dipolar de 1%, para as condicoes do Observatorio Pierre Auger, para atingir um valor de significância consideravel, de 3, valor minimo necessario para dar atencao a possivel existencia de anisotropia dipolar Abstract

Analyses of dispersive effects and the distributed capacitance in the time and frequency domains of activated carbon nanofiber electrodes as symmetric supercapacitors

Electrochimica Acta

The Journal of Physical Chemistry C

Electrolyte-insulator-semiconductor devices with different integrated reference electrodes for pH detection

Journal of Vacuum Science & Technology B

High Capacitance Nitric Acid-Functionalized MWCNT/PANI composite Supercapacitors under operando conditions

Resumos do...

Exploring doped or vacancy-modified graphene-based electrodes for applications in asymmetric supercapacitors

Physical Chemistry Chemical Physics

We report here density functional theory calculations and molecular dynamics atomistic simulation... more

Radially ordered carbon nanotubes performance for li-o2 batteries: Pre-treatment influence on capacity and discharge products

Catalysis Today

Multi-walled carbon nanotubes and activated carbon composite material as electrodes for electrochemical capacitors

Journal of Energy Storage

Highly stable nickel-aluminum alloy current collectors and highly defective multi-walled carbon nanotubes active material for neutral aqueous-based electrochemical capacitors

Journal of Energy Storage

Nickel oxide nanoparticles supported onto oriented multi-walled carbon nanotube as electrodes for electrochemical capacitors

Electrochimica Acta

Environmentally friendly functionalization of porous carbon electrodes for aqueous based electrochemical capacitors

IEEE Transactions on Nanotechnology

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