TiO2 Synthesis by Pechini Method and Application in Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSC) are devices to solar energy conversion, which present low production costs and high photoelectrochemical stability. The aim of this study was to investigate the synthesis of TiO2 by Pechini methodology, using C12H28O4Ti and TiCl3 as precursors, and their application in solar cell sensitized by N719 dye. The characterization techniques employed were Scanning Electron Microscopy (SEM), UV-VIS Spectroscopy, X-ray diffraction (XRD), photochronoamperometry, j-V Curves and EIS plots. The results demonstrated a high crystallinity and surface area to particles obtained with C12H28O4Ti as precursor. The highest photoconversion energy efficiency reached was to TiO2 using C12H28O4Ti with PCE= 4.17±0.13% with photoelectrochemical parameters of jsc= 5.53 ±0.08, Voc= 0.78±0.07 FF=0.58±0.05 and less resistive to charge transport with τe= 53 ms. DOI: http://dx.doi.org/10.17807/orbital.v13i2.144

Uma alternativa sustentável: aplicação do resíduo do ácido 3,5 dinitro salícilico em células solares / An sustainable alternative: application of 3,5 dinitrosalicylic acid residue in solar cells

Células solares sensibilizadas por corante (CSSC) são dispositivos promissores para conversão de energia. Os corantes empregados nas CSSCs, geralmente baseados em rutênio, são sintéticos e, apresentam um custo elevado, conduzindo ao estudo de novos materiais fotossensibilizadores para serem aplicados. Uma alternativa sustentável é a utilização do ácido 3,5 dinitrosalícilio (DNS) e do seu resíduo após a análise de açúcares redutores, o 3-amino 5–nitrosalícilio (ANS), que é tóxico ao meio ambiente e não têm valor comercial após utilização. Este trabalho teve como objetivo produzir e analisar um sistema fotovoltaico contendo DNS e ANS, com fins de se agregar valor e incentivar a aplicação sustentável de descartes poluentes. As técnicas empregadas foram Espectroscopia na região do Ultravioleta – visível (Vis), fotocronoamperometria (j-t) e curvas de densidade de corrente em função do potencial (j- E). Os corantes empregados apresentaram bandas de absorção na região do visível e foram capazes de produzir um dispositivo fotovoltaico como verificado pelas análises foto-eletroquímicas, com uma foto-corrente de 55 µA cm-2 para o DNS e 20 µA cm-2 para o resíduo

Application of Zinc Oxide Nanospheres for Hybrid Solar Cell

Poly(3-alkylthiophenes), P3AT, are organic polymers formed by conjugate structures with conductive properties. Zinc oxide (ZnO) has been used as an electron acceptor in hybrid solar cells because it offers electron transport properties and can be synthesized by methods in which the variation of synthesis parameters allows morphological control. Different ZnO morphologies allow for distinct properties in terms of electronic transport at the interface of solar cells. ZnO particles were synthesized by the co-precipitation method. ZnO films were deposited by spin-coating in Fluorine Tin Oxide (FTO) and then immersed in solutions containing poly (3-hexylthiophene) (P3HT) or poly (3-octylthiophene) (P3OT) polymers. The cell was assembled in the form of a sandwich consisting of: FTO/ZnO,P3AT/Iˉ,I3ˉ/Pt/FTO. UV-vis measurements were performed for bandgap calculation, scanning electron microscopy (SEM), X-ray diffraction (XRD), and J-V curves. The ZnO/P3HT cell presented the best values of J, V and η, indicating an improvement in the electronic transfer processes, with a value of η = 0.56%. DOI: http://dx.doi.org/10.17807/orbital.v13i2.145

Persea pyrifolia Peel Extract as a Carbon Steel Corrosion Inhibitor

Carbon steel is one of the most widely used alloys in industrial applications. However, the use of this metal may be limited because of corrosion tendency. Thus, it is necessary to develop methods that inhibit its degradation. One way to inhibit corrosion is to use organic inhibitors. Some organic compounds with heteroatoms inhibit corrosion by forming a protective film. In this study, the corrosion inhibition of carbon steel 1020 in 0.1 mol L-1 hydrochloric acid medium was evaluated. The natural inhibitor used was an aqueous extract of the bark of Persea pyrifolia (PP) plant at concentrations of 2.5, 5 and 10% V / V. The electrochemical response was determined by open circuit potential measurements, electrochemical impedance spectroscopy, and anodic potentiodynamic polarization. Therefore, mass loss was measured, and inhibitory efficiency was evaluated. The best results were observed for the concentration of 2.5% V / V of Persea pyrifolia extract, presenting and inhibition efficiency of 82.5% on the 1020 carbon steel. The electrochemical results indicates that PP extract can be used as green corrosion inhibitor in acidic medium. DOI: http://dx.doi.org/10.17807/orbital.v13i2.146

The influence of Annona muricata L. peel extract as a potent source of natural antioxidant on soybean oxidation stability: A influência do extrato de Annona muricata L. peel como uma potente fonte de antioxidante natural na estabilidade da oxidação da soja

Antioxidants are an alternative to prevent or retard biodiesel degradation. Soursop (Annona muricata L.) is a native tropical fruit with important antioxidant activity, besides high concentration of phenolic compounds. Peels form about 20 % of the soursop fruit composition and are usually discarded as a waste product. In this study the antioxidant potential of different peel extracts was evaluated by oxidative stability when used as an additive into soybean biodiesel. All samples were analyzed by the Rancimat® 873, using 32 experimental design. The tests were performed with biodiesel B100 with solutions extracted in different conditions, such as pH and residue concentrations. Results demonstrated that all experiments were able to increase significantly the induction period (IP), when compared to a pure biodiesel control sample, and showed similar efficiency with synthetic antioxidants (BHT). Among all experiments, each neutral and alkaline extractions presented induction periods over 8 h, achieving and surpassing the minimum allowed by European standard. However, the highest IP was found to be 10.30 h, with 3 g L-1 in neutral extraction.  Results corroborate that soursop peel has a high antioxidant capacity and efficiency to improve the oxidation stability, and could be used as an inexpensive natural antioxidant to biodiesel

Influence of Deposition Methodology and Heating Treatment on Dye Sensitized Solar Cell with Natural Extract

In this study, it was investigated the photovoltaic parameters of Dye Sensitized Solar Cells (DSSC) and the thin coating morphology of TiO2 by Doctor Blading and Spin Coating methods, sintered at 450 ºC and 450 ºC with a heating rate of 0.4 ºC s-1, using a natural dye extract from Hibiscus. These properties were studied by scanning electron microscopy (SEM), photochronoamperometry and curves j-V. It was demonstrated that all solar cells produced are photosensitive with an excellent charge injection. The cell with a better energy conversion (jsc = 0.53 mA cm-2; Voc= 0.471 V and FF= 0.518), uniform and flawless morphology was obtained to cell coated by Doctor Blading method, with a heat treatment of 450 ºC/0.4 ºC s-1. DOI: http://dx.doi.org/10.17807/orbital.v10i3.1101</p

COMPARATIVE STUDY OF TiO2 AND ZnO APPLICATION IN HYBRID SOLAR CELLS USING COPOLYMER P3OT/P3MT

Hybrid inorganic-organic solar cells are an attractive alternative energy source because of their low-cost production and ability to make use of a large amount of solar radiation available. This work aims to evaluate different solar cells composed of TiO2 and ZnO with P3OT/P3MT copolymer. Layers of semiconductor oxides were deposited on transparent fluorine-doped tin oxide (FTO) by spin coating and adsorption in the polymer solution. X-ray diffraction (XRD), scanning electron microscopy (SEM), were used to characterize the fabricated semiconductors and curves of current density vs. potential (j-V), photochronoamperometry (j-t) and electrochemical impedance spectroscopy (EIS) were used to determine their electrical characteristics. The XRD analyses confirmed the crystalline nature of the oxide materials. SEM micrographs showed the spherical morphology of ZnO and the poorly defined agglomerate morphology of TiO2. The electrochemical measurements proved that the best cell was produced with P3OT/P3MT copolymer and TiO2, owing to its lower charge transfer resistance, with the following photovoltaic parameters: Voc = 0.615 V ± 0.004, jsc = 1.545 mA cm-2 ± 0.240, FF = 0.637 ± 0.003, and η = 0.617% ± 0.117