Seminars
The urgency of renewable energy
DR. ANTONIO MAIA DE JESUS CHAVES NETO - UFPA/ BRAZIL
Date: October 7, 2021 ( 13:00 PM, Brazil, time)
The COVID-19 virus pandemic has caused worldwide confusion and showing and accelerating social and economic differences between all countries in the world. New economies are coming back stronger, accentuating the gap with poorer countries. Thus, when the fossil fuel energies fail and the additional pollution caused, it will take even greater dimensions. In fact, this phase has already started. The purpose of this presentation is an overview of the general status of the importance of renewable energy generation and nanotechnology in the world. The processes of damage due to CO2 and greenhouse gases in the atmosphere and the attack on coral reefs. The effects of burning forests and fossil and/or non-fossil fuels on the environment causing the greenhouse effect that leads to changes in human behavior in relation to the good use of natural resources, including in the system of laws and architecture. Taking the importance of accelerating new renewable energy systems and improving existing systems. We will present the new trends in clean energy and care for the environment.
Photovoltaic Solar Energy: From Quartz to Silicon, Cells, Panels and Photovoltaic Systems
DR. Francisco das Chagas Marques, Physics Institute, University of Campinas (UNICAMP)
Date: October 7, 2021 (14:00 PM, Brazil, time)
The primary energy sources currently used in the world come from fossil fuels (oil, natural gas and coal), in addition to nuclear and hydroelectric energy. All of them pose serious environmental problems, including hydroelectric power, with most natural reserves running out. Several proposals were investigated and adopted on a smaller scale to overcome these problems, with photovoltaic conversion being undoubtedly one of the most prominent in the current scenario. Solar panels require little maintenance, have a useful life of over 25 years, do not generate waste, noise or pollutants that contribute to acid rain and urban pollution. In this lecture, the concepts of photovoltaic solar energy generation will be presented; the silicon purification processes; manufacture of conventional and third generation solar cells; photovoltaic panels; photovoltaic plants and the world panorama of the use of photovoltaic systems
Asymmetric Charge Transfer from Pyrene Dyads: Using Amides to Control Photochemistry of Pyrene
DR. Eli M. Espinoza, Naval Air Warfare Center Weapons Division, Chemistry Branch
Date: October 7, 2021 (15:00 PM, Brazil, time)
Amide bonds are ubiquitous in nature as well in organic chemistry. In biological systems, besides holding together peptide bonds, amide bonds contribute to the dipole moment via hydrogen bonding making alpha helices natural electrets. In aromatic and polyaromatic hydrocarbons (PAH’s), amide bonds contribute to the electronic properties as well as means for covalent attachment. We have previously shown that the position of the amide bond on PAH’s shifts oxidation or reduction potentials of pyrene by about 100-200 mV, which are in agreeance with the Swain-Lupton parameters. Symmetry breaking (SB) charge transfer (CT) processes occurs when symmetrical molecules, upon photoexcitation, undergo a process which makes one molecule an electron donor, and its symmetrical counterpart, an electron acceptor, in the excited state thus creating holes and electrons. Factors such as change in dipole, hydrogen bonding, halogen interactions, etc...
Problem Based Learning and Renewable Energy Sources in the scenario of the Brazilian New High School
Dr. Silvana Perez, UFPA
Date: October 13, 2021 (14:00 PM, Brazil, time)
In this presentation, I will talk about Problem Based Learning in the scenario of the New Brazilian High School, bringing the theme of alternative energy sources. Formal school education worldwide has been undergoing a change of paradigm in recent decades, in the search for the formation of critical citizens aware of their role in social and environmental issues that arise in modernity. Competency teaching is part of this reality and Problem Based Learning aims to develop conceptual, attitudinal and procedural skills in students. Therefore, I will present a summary of the general competences foreseen in the new Brazilian Common National Base for Basic Education, in particular considering the themes related to Renewable Energy Sources.
Hydrogen Production by Electrochemical Alcohol Reforming. A key solution for a decarbonization of the transport sector.
DR. Germano Tremiliosi-Filho, Institute of Chemistry of São Carlos – University of São Paulo, Brazil
Date: October 13, 2021 (15:00 PM, Brazil time)
The growth of the technological civilization has been supported mainly on the use of fossil fuels, such as coal, natural gas, and hydrocarbons, for the production of both energy and chemicals. As a consequence of burning fossil fuels leads to the emission of the CO2 in atmosphere, which is a greenhouse gas and represents one of the main contributions to the global climate change. Hydrogen is considered the most significant candidate in technology innovation, economic expansion, and global progression in the 21st century....
High quality Structural refinement of nanoparticle atomic arrangement from Pair distribution Function derived from Precession Electron diffraction in a TEM
Dr. Daniel Ugarte, Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas-UNICAMP,Campinas - SP, Brazil
Date: October 14, 2021 (14:00 PM, Brazil, time)
Nanoparticles (NPs) attract a great deal of interest in science and technology, due to the possibility of controlling their properties by changing size and structure. The atomic arrangement in NPs may be quite different from bulk materials, however the access to reliable and quantitative structural characterization tools for this size regime is still an open issue. Bulk crystals display long-range atomic order, and x-ray diffraction analysis fulfils requirements of precision and easy use. Nanomaterials are in between amorphous systems (short-range order) and bulk crystals, then diffraction patterns contains less information due to peak broadening, low signal, high background and higher thermal vibrations. This leads, leads to a lack of sufficient constrains to the required fitting free variables (atomic positions). Transmission Electron Microscopy (TEM) is the most popular NP characterization approach, but analysis are mostly qualitative and many times lack of the number of repetitions to confirm the reliable assessment from the statistical point of view. In this work, we report a structural refinement approach to gather quantitive information on NP atomic arrangement using pair distribution function (PDF) calculated from precession electron diffraction (PED).
Electron-deficient photosensitizers: How to make nitroaromatics fluoresce?
DR. Valentine I. Vullev, University of California, Riversid
Date: October 14, 2021 ( 15:00 PM, Brazil, time)
Organic aromatic compounds are building blocks for a wide variety of p-type materials and potent photoreductants. Conversely, n-type organic conjugates are few and far between. The election-withdrawing strength of nitro groups makes them promising substituents for attaining such n-type systems. Nitro groups induce positive shifts in the reduction potentials of polycyclic hydrocarbons, such as pyrene, that exceed 1 V. The shifts induced by nitrile and carbonyls range between 0.2 and 0.7 V. Optically excited states of most nitroorganics, however, undergo fast non-radiative decays. That is, nitro groups are efficient fluorescence quenchers, rendering these compounds unfeasible for a wide range of applications such as photosensitization and photooxidation.
Strategies to improve the efficiency of photoelectrochemical water splitting systems
Dr. Gerko Oskam, Department of Applied Physics, CINVESTAV-IPN, Mérida, Yucatán, México
Date: October 15, 2021 (14:00 PM, Brazil, time)
Direct solar water splitting is an attractive option for the generation of hydrogen as a energy vector for both chemical energy storage and clean fuel. The general idea is to use a semiconductor material to absorb sunlight, generating free electrons in the conduction band and free holes in the valence band, which are eventually used to reduce and oxidize water, respectively. In order to achieve efficient and sustained conversion of solar energy to hydrogen, however, several critical conditions need to be fulfilled: (i) The semiconductor must be stable under illumination in an aqueous solution; (ii) the semiconductor must absorb a significant fraction of the solar spectrum; and (iii) the electron and holes generated need to be efficiently separated and transferred to the aqueous solution, in order to prevent recombination. History has shown that achieving these conditions is very challenging and we are currently nowhere near the implementation of a commercially viable system.
IMPEDANCE SPECTROSCOPY ANALYSIS OF THIRD GENERATION SOLAR CELLS
DR. Juan Antonio Anta, Universidad Pablo de Olavide de Sevilla
October 15, 2021 (15:00 PM, Brazil, time)
In this lesson, I will present the foundations and applications of impedance spectroscopy, in particular in the context of the analysis of emerging photovoltaic devices, such as dye sensitized solar cells and perovskite solar cells. For instance, metal halide perovskites are mixed electronic-ionic semiconductors with an extraordinary rich optoelectronic behavior and the capability to function very efficiently as active layers in solar cells, with a record efficiency surpassing 24% nowadays....
Interactive materials design towards a sustainable world
DR. Caetano Rodrigues Miranda, Instituto de Física, USP
Date: October 28, 2021 (14:00 PM, Brazil, time)
This talk will present recent contributions on computational materials discovery, ranging from carbon neutralization to energy transition [1-2]. Here, we have been inspired by the Sustainable Development Goals (SDGs) by the United Nations and the social role of Physics and Materials Science in developing technologies for a sustainable world. We apply a combination of data analytics and multiscale materials modeling to accelerate the materials discovery process and unveil the molecular mechanisms behind catalytic processes. ..
Closing the Wren 2021, Dr. Antonio Maia de Jesus Chaves Neto - UFPA/ Brazil.
DR. ANTONIO MAIA DE JESUS CHAVES NETO - UFPA/ BRAZIL
Date: October 28, 2021 ( 15:00 PM, Brazil, time)
Closing the Wren 2021, Dr. Antonio Maia de Jesus Chaves Neto - UFPA/ Brazil.