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Transparent nature-based luminescent solar concentrator with NIR emission and integrated thermal sensing
Publication . Correia, Sandra F. H.; P. Falcão, Bruno; Figueiredo, Gonçalo; Vaz, Bárbara M. C.; Contieri, Letícia S.; Mesquita, Leonardo M. de Souza; Almeida, Juliana; Fradinho, Joana C.; Pinto, Diana C. G. A.; Fu, Lianshe; André, Paulo S.; Ventura, Sónia P. M.; Ferreira, Rute A. S.; Sencadas, Vitor; UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; LAQV@REQUIMTE; RSC - Royal Society of Chemistry
The engineering of luminescent solar concentrators (LSCs) offers a way to turn windows into energy-generating units while maintaining transparency. Through UV/blue down-shifting materials to the red/near-infrared (NIR) spectral region, the performance of building integrated photovoltaics is maximized without compromising indoor light quality. The most efficient solutions are based on quantum dots, which raise environmental concerns. To address this, natural renewable materials, like bacteriochlorophyll (BChl) from phototrophic bacteria were used to fabricate an LSC prototype dispersed in a styrene-ethylene-butylene-styrene (SEBS) matrix. The LSCs emit in the red/NIR region with an emission quantum yield of ∼7%, demonstrating external photon efficiency and electrical device efficiency values of ∼1.0% and ∼0.04%, respectively. The thermal dependence of the BChl/SEBS emission is used to set two independent thermometric parameters based on the emission and the electrical power generated by the LSC edge-mounted photovoltaic cells with relative sensitivity values up to ∼2% °C−1, which is a remarkable performance. This prototype was scaled up for an active area of 0.1 m2, representing the first large-area LSC using nature-based red/NIR emission centers.
Enhancing the efficiency of luminescent solar concentrators via soft colloidal lithography negative templating
Publication . Guerrero-Felix, J. G.; Correia, S. F. H.; Alexandre, M.; Gonzalez-Gomez, C. D.; Sencadas, V.; Fu, L.; Ruiz-Reina, E.; André, Paulo Sérgio B.; Moraila-Martinez, C. L.; Mendes, M. J.; Ferreira, R. A. S.; Fernandez-Rodriguez, M. A.; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Elsevier
Building-integrated photovoltaics (BIPV) offers a sustainable pathway by seamlessly incorporating PV cells into architectural elements like façades and windows. In this study, we investigate the potential of luminescent down-shifting solar concentrators in combination with a nanophotonic light-trapping scheme to improve the optical-guiding capabilities and thereby enhance the energy conversion efficiency. We propose a novel cost-effective method to fabricate the photonic structures via soft colloidal lithography negative templating of thin films of TiO2 nanoparticles, successfully scaling the production to 11x11 cm2 glass windows. Through simulations and optical-electrical characterization, we demonstrate substantial improvements in energy harvesting for different angles of solar irradiation. We found increases in power output ranging from 57% for angles of incidence below 45° to above 100% for 60° thanks to the nanostructured TiO2 nanoparticles coatings added to a bottom down-shifting layer. This shows that such integrated approach can enhance both the efficiency and aesthetic appeal of solar solutions in urban environments, advancing the design of energy-efficient, sustainable buildings. Our methodology ensures consistent solar energy capture all year-round, for the relevant range of sunlight incidence angles, while preserving the transparency and multifunctionality of building elements.
Hybrid nanocomposites of Fe3O4/SiO2-EDTA
Publication . Santos, Gabriela T.A.D.; Estrada, Ana C.; Amorim, Carlos O.; Amaral, João S.; Deuermeier, Jonas; Duarte, Armando C.; Santos, Patrícia S.M.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Elsevier
Fe3O4/SiO2-EDTA materials have been used for diverse applications and they have been modification by different methods, but a comparison is lacking between their physicochemical characteristics. This work aimed to compare the physicochemical characteristics of the Fe3O4/SiO2-EDTA nanocomposite obtained by four methods, whose modification of the Fe3O4 surface with SiO2-EDTA occurs in one or two steps, with not hazardous chemicals. In the one-step methods (M1 and M2), Fe3O4 particles were coated and functionalized in consecutive steps (by sonication in M1 and mechanical stirring in M2). In the two-step methods (M3 and M4), the Fe3O4 particles were primarily coated with silica and then functionalized with TMS-EDTA (by sonication in M3 and mechanical stirring in M4). The Fe3O4/SiO2-EDTA nanocomposites were characterized by XRD, TEM, EDX, BET, SQUID magnetometry, FTIR, XPS, and zeta potential. The TEM highlighted that the nanocomposites from methods M1 and M2 there is the simultaneous presence of magnetite particles coated and uncoated with silica, while those from M3 and M4 were totally coated, besides the nanocomposites from M2 and M3 showed to be more aggregated than those from the other methods. The presence of EDTA on the surface of the nanocomposites was evidenced by the carboxyl groups in the FTIR spectra and by the nitrogen in the XPS spectra. The nanocomposites from M3 and M4 presented a higher content of nitrogen than those from M1 and M2, and those from M4 also presented a higher content of carbon than those from M3. Overall, the Fe3O4/SiO2-EDTA nanocomposites from two-step methods showed better SiO2 coating and EDTA functionalization than those from one-step methods, and those from M4 presented the best physicochemical characteristics, being this method recommended for their modification for future applications.
Laser-induced copper superhydrophobicity to improve heat transfer and reduce limestone deposition in water heating systems
Publication . Gaspar, Guilherme; Salvador, Maria A.; Pereira, Maria J.; Carvalho, Alexandre F.; Amaral, Vitor S.; Tedim, João; Deuermeier, Jonas; Fernandes, António J. S.; Silva, Rui F.; Costa, Florinda M.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; North-Holland | Elsevier
The spectroscopic and electrochemical properties of copper (Cu) superhydrophobic surfaces produced from laser scribing operating in the nanosecond pulsing regime are reported herein. µ-Raman spectroscopy highlighted the synthesis of copper oxide films with the simultaneous sharp increase of the substrates’ specific surface area through one single laser processing step. Higher laser power densities resulted in cupric oxide (CuO) with higher crystallinity and more homogeneous surface chemistry, whereas cuprous oxide (Cu2O) dominates surfaces processed at lower laser power densities. Steady-state contact angles using water of 162° ± 9° were measured for the lowest laser power employed, representing a grounded and meaningful development for substrates of this kind using laser technology. The results show that the combination of surface roughness and the presence of Cu2O and hydrocarbon chains at the surface contributed to the superhydrophobicity of the copper foils. Additionally, variations in the thermal conductivity of the samples’ surface are influenced by changes in the chemical composition. The surfaces were exposed to limestone-rich water and the amount of deposited solute was quantified using atomic absorption spectrometry. A fivefold reduction in calcium carbonate (CaCO3) was observed, unequivocally demonstrating the impact of laser treatments in reducing CaCO3 nucleation rates in Cu for water heating applications.
Neodymium removal and recovery from simulated NdFeB leachate using manganese ferrite nanoparticles
Publication . Sousa, Joana; Tavares, Daniela S.; Pinto, João; Henriques, Bruno; Rocha, João; Trindade, Tito; Lapa, Nuno; Pereira, Eduarda; DQ - Departamento de Química; LAQV@REQUIMTE; Elsevier
This study explores the use of manganese ferrite nanoparticles (MnFe2O4) for the removal and recovery of neodymium (Nd) from aqueous solutions, focusing on their potential application in wastewater treatment and environmental remediation. Neodymium, a critical element for the high-technology and energy industries, is increasingly present in aquatic environments due to its widespread use in devices such as computers, electric vehicles, and wind turbines. Through a series of kinetic, equilibrium, and desorption tests, the study optimized key operational parameters using Response Surface Methodology. Equilibrium analyses revealed that the Nd removal at equilibrium (qe) reached 8 mg/g, while the maximum sorption capacity (qm) was determined to be 9.2 mg/g. The results demonstrated a high removal efficiency (up to 90 %) under optimal conditions, which included a nanoparticle dose of 1000 mg/L, an initial neodymium concentration of 20 μmol/L, pH 6, and no salinity. The material showed great potential for neodymium recovery from synthetic magnet solutions, with removal rates exceeding 70 %. Desorption tests confirmed complete recyclability of the sorbent. These findings highlight manganese ferrite nanoparticles as a promising and sustainable approach for neodymium recovery.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de avaliação no âmbito do Programa Plurianual de Financiamento de Unidades de I&D (2017/2018) - Financiamento Programático
Número da atribuição
UIDP/50011/2020