Colóquios

Palestrante: Prof. Dr. Eudes Eterno Fileti ( Unifesp)
Título: Supercapacitores: Maximizando a eficiência no armazenamento de energia eletroquímica
Data: 14/10 às 16hCarta de comparecimento
Link: https://youtu.be/aOUPNNdY1FI

Resumo: Os supercapacitores são certamente uma das classes mais promissoras de dispositivos de armazenamento de energia eletroquímica. Com características entre os capacitares convencionais e as baterias eles têm mostrado enorme potencial tecnológico. Nesse seminário você vai compreender o funcionamento de um supercapacitor e ter noção de como a modelagem computacional tem sido usada para promover a busca constante pela otimização do desempenho destes dispositivos.

PRÓXIMOS COLÓQUIOS

Palestrante: Prof. Dr. Ado Jório (UFMG)
Título: Nano-espectroscopia em materiais bi-dimensionais
Data: 21/10 às 16h
Link: https://youtu.be/YoBbt-vTtDo

Resumo: Neste seminário, o desenvolvimento e aplicacação de um instrumento para nano-espectroscopia óptica serão discutidos. Efeitos de localização espacial em grafeno, mono- e di-calcogenetos de metais de transição serão abordados, com enfoque no campo da twistrônica.

Palestrante: Prof. Dr. Erick Bastos (IQ/USP)
Título: Uma aventura entre Flores, Beterrabas e cores que começou com a UFABC
Data: 04/11 às 16h
Link: https://youtu.be/S9HaybCpIVc

Resumo: Erick Leite Bastos, Instituto de Química da USP, http://lattes.cnpq.br/1765001992629979
15 anos atrás, eu fui contratado como docente da UFABC e o sonho de transformar moléculas obtidas de plantas em produtos com valor agregado começou. Neste seminário, vou contar a trajetória que nos levou a desenvolver a BeetBlue, um corante pseudo-natural seguro produzido a partir de pigmentos encontrados em flores fluorescentes e na beterraba.

COLÓQUIOS ANTERIORES

Palestrante: Prof. Dr. Alexandre R. Rocha
Título: How Machine can help us learn about water: neural networks applied to liquids
Data: 07/10 às 16hCarta de comparecimento
Link: https://youtu.be/Trz4v5SAAjA

Resumo: Water is, undoubtedly, one of the most important substances known. It is a key resource required for the existence of life as we know. Albeit the liquid is formed by a seemingly simple molecule, the interplay between long and short range interactions at the atomic and molecular level leads to a set of properties that make this liquid so unique. In that sense, accurate microscopic theoretical predictions are hard to come by.
On the one hand, classical force fields used to simulate the dynamics of the liquid, typically require some experimental input. In that sense, they are usually good for computing some physical quantities, while failing in other cases. On the other hand, first principles methods such as density functional theory, are usually limited to small systems and short times scales and good predictive capabilites are hindered by the approximations to the exchange and correlation approximations that are inherent to the method. In this talk I will address some of these issues, and how neural networks fitted on top of accurate density functional calculations can help us understand the properties of bulk water. In particular, I will show how we can obtain force fields that allow us to accurately simulate large systems and long time scales. I will argue that this is extremely important for obtaining good comparison with experimental results.

Palestrante: Prof Dr Alexandre Fontes da Fonseca
Título: Twisting twisted graphene nanoribbons without twisting
Data: 30/09 às 16h – Carta de comparecimento
Link: https://youtu.be/IYpZCQoRVdc

Resumo: The common sense regarding twisting or untwisting a ribbon is that it requires the application of an external rotation to happen. However, at nanoscale, the application of precise  amounts of rotation on a nanoribbon is not a trivial task. Here, the concept of an alternative method to add  twist to or remove twist from a twisted graphene nanoribbon (TGNR) without rotation is presented and computationally demonstrated. The possibility of fine-tuning the amount of twist of a  TGNR is also shown. Besides being capable of precisely determining the  total twist of a TGNR, this concept reveals a twist to writhe transition phenomenon  that is tension-free and does not require controlling either the nanoribbon end-to-end distance or its critical  twist density.

Palestrante: Profa Dra Ana Flávia Nogueira
Título: Metal halide perovskites: a journey through structure, properties and stability
Data: 23/09 às 16h – Carta de comparecimento
Link: www.youtube.com/watch?v=iaUFNG2exGE

Resumo: Metal halide perovskite solar cells have reached the recent efficiency breakthrough of 25.5%. Such fantastic result was only possible due to a precise control and engineering of the morphology, interfaces and the use of multiple cations in perovskite A-site, as Rb, Cs, MA and FA. For tandem perovskite solar cells, a mixture of different anions, as Br and I is also desired to adjust the band gap. Such cocktail of different cations and anions influences the formation of intermediates, phases, favours halide homogenization, etc. In this presentation, we will summarize important results using in situ experiments to probe halide perovskite formation (2D and 3D), stability and composition. We employed time-resolved grazing incidence wide angle x-rayscattering (GIWAXS), small angle x-ray scattering (SAXS) and high-resolution XRD. In situ GIWAXS experiments allowed us to understand the influence of the relative humidity and time to drop the antisolvent during the preparation of perovskite films [1]. It is well known that a 2D layer on the top of a 3D bulk perovskite improves stability and performance. In situ GIWAXS revealed us that during thermal annealing the 2D layer transforms itself into a disorder layer, improving hole transfer and stability [2]. This technique was also employed to identify the first intermediates formed during the degradation of different Cs and Br perovskite compositions under ambient conditions [3]. In situ SAXS is another powerful technique to follow the first stages of the 2D perosvkite’s formation. Our results suggest that the formation of the individual slabs in BA2[FAPbI3]PbI4 is quite fast (within the first 10 s) and, then, these slabs self-assemble into bulk crystallites during the next 40 minutes [4]. [1] R. Szostak, S. Sanchez, P. E. Marchezi, … A. Hagfeldt, A. F. Nogueira, “Revealing the perovskite film formation using the gas quenching method by in situ GIWAXS: morphology, properties and device performance”, Advanced Functional Materials, 31(4) 2007473 (2021) [2] A. Sutanto, R. Szostak, …, A. F. Nogueira, G. Grancini “In Situ Analysis Reveals the Role of 2D Perovskite in Preventing Thermal-Induced Degradation in 2D/3D Perovskite Interfaces”, Nano Letters, 20(5) 3992-3998 (2020) [3] P. E. Marchezi…, M. F. Toney, A. F. Nogueira, “Degradation mechanisms in mixed-cation and mixed-halide CsxFA1-xPb(BryI1-y)3 perovskite films under ambient conditions” J. Mater. Chem. A,9, 9302-9312 (2020) [4] R. F. Moral, L. G. Bonato, J. C. Germino, W. X. Oliveira, R. Kamat, J. Xu, C. Tassone, D. D. Stranks, M. F. Toney, A. F. Nogueira, “Synthesis of Polycrystalline Ruddlesden-Popper Organic Lead Halides and Their Growth Dynamics”, Chemistry of Materials, 31 (22) (2019), 9472-947. Caso você faça parte do programa da pós entre em contato para participar da webconferência.