Maria Elena Nicho

Harnessing the synergistic effects of composite materials enables the design of smart windows with improved performance. Furthermore, the utilization of agro‐industrial waste is desirable to promote the circular economy and contribute to environmental and health care. In this work, in situ synthesized composites based on poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and silicon dioxide (SiO ₂ ) extracted from a natural source (sugarcane bagasse) are investigated. The effect of acid treatment of sugarcane bagasse fibers and variations in SiO ₂ concentration in P3HT on the physicochemical properties of the compound are studied. The composites are characterized by infrared and ultraviolet–visible spectroscopy, X‐ray diffraction, cyclic voltammetry, scanning electron microscopy/energy dispersive spectroscopy, and atomic force microscopy. The results show that the properties of P3HT improve with the addition of SiO ₂ extracted from sugarcane bagasse, corroborating an increase in conjugation length, polymer chain arrangement, and stored charge, as well as a decrease in the bandgap. Furthermore, the synthesized composites are tested in dual electrochromic devices (DEDs) using the GLASS/ITO/COMPOSITE/PE/PANI/ITO/GLASS configuration. DEDs show higher optical contrast and more stable optical kinetics when incorporating SiO ₂ into P3HT. The addition of SiO ₂ to P3HT increases the optical contrast of dual DEDs by up to 126.9%, offering an alternative for the development of electrochromic devices.

Sargassum has become an “ecological disaster” on most beaches in the Caribbean Sea, causing serious health, safety, economic and environmental problems. The objective of this study was to valorize sargassum for the extraction of sodium alginate, cellulose and cellulose nanocrystals. Cellulose was also used in the manufacture of a separator for an energy storage device (ESD) based on expanded graphite and activated carbon. Sargassum was characterized physicochemically; the results of this characterization are very relevant for the generation of bioenergy and removal of toxic contaminants. The extracted materials were identified by FT-IR; the spectra were very similar to the IR spectra of commercial samples, which corroborated that the materials extracted were sodium alginate, cellulose and cellulose nanocrystals. The performance of the ESD/cellulose-based separator was determined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Additionally, an RC circuit and an oscilloscope were used to perform a charge/discharge test. The voltammograms obtained for the ESD showed a rectangular shape with redox peaks characteristic of a pseudocapacitor and a battery, and the Nyquist plot showed a typical electrochemical performance of such ESD. Likewise, the developed devices have the capacity to store and release energy in seconds.

Polyvinylidene fluoride (PVDF) has interesting properties for piezoelectricity, making it a suitable material for energy harvesting applications. Combined with another polymer, polymethylmethacrylate (PMMA), it forms a composite with greater efficiency in energy conversion. This article describes how a PVDF/PMMA composite with variable concentration of the constituents is synthetized and characterized. The versatility of material formation represents an opportunity to reduce process costs improving performance. The goal is to establish a proven procedure that confirms the relevance of the PVDF/PMMA composite in energy conversion depending on the specific composition and load for tire energy harvesting.

Herein, we report the synthesis of nontoxic pyrite iron sulfide (FeS₂) nanocrystals (NCs) using a two-pot method. Moreover, we study the influence of these NCs incorporated into the PTB7:PC₇₁BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC₇₁BM:FeS₂/PFN/FM. The Field’s metal (FM) is a eutectic alloy composed of 32.5% Bi, 51% In and 16.5% Sn by weight that melts at 62 °C. It is deposited on the active layer/PFN under atmospheric conditions. Ternary active layers are prepared by adding small amounts of the semiconducting FeS₂ NCs at different weight ratios of 0.0, 0.25, 0.5, and 1.0 wt % with respect to the electron donor PTB7. With respect to the reference device (without FeS₂), a 21% increase in the power conversion efficiency (PCE) is observed for OPVs with 0.5 wt % FeS₂, such that the PCE of the OPVs is enhanced from 5.69 to 6.47%. According to the Kruskal–Wallis and Mann–Whitney statistical tests, all OPV devices follow the same trend.