Resultados de investigación

Video S2: In situ absorption spectroscopy of MAPbBr3 NPL growth over the whole reaction time scale (AVI), Lead halide perovskite nanoplatelets (LHP NPLs) are of immense interest in the materials science and optoelectronics communities owing to their strong quantum confinement leading to narrow emission peaks, thickness-dependent tunable photoluminescence, and large exciton binding energies. Thus far, their further development and photophysical investigations at ensemble and single-particle levels have been impeded by suboptimal ligand passivation, inferior environmental and colloidal stability compared to their 3D nanocrystal counterparts, and limited compositional diversity. Here, we report highly monodisperse methylammonium lead bromide (MAPbBr3) NPLs (11.3 ± 2.3 × 1.7 ± 0.5 nm) with tunable ligand chemistry and enhanced photoluminescence quantum yields of up to 80%. NPLs capped with zwitterionic ligands exhibit improved stability upon air exposure and sequential purification. Nuclear magnetic resonance spectroscopy on ligand-exchanged NPLs, capped with either phosphocholine- or phosphoethanolamine-type ligands, confirms the partial replacement of the pristine ligands. Owing to the size and shape uniformity of synthesized MAPbBr3 NPLs, they readily form assemblies of stacked face-to-face NPLs, as observed in both colloidal dispersions and films, giving rise to concentration-dependent multicolor emission. The temperature dependence of the NPL emission exhibits a nonmonotonous trend, attributed to the highly anisotropic confinement and the consequent exciton–phonon coupling. We also observed photoluminescence from single MAPbBr3 NPLs at both room and cryogenic temperatures, revealing highly polarized fine-structure emission lines with single-photon purity exceeding 80%. The high uniformity and optical transparency of MAPbBr3 NPL films enabled their integration into optical cavities, where they exhibited strong light-matter coupling with a substantial Rabi splitting of 200 meV., Peer reviewed

Video S1: In situ absorption spectroscopy of MAPbBr3 NPL growth during the initial stages of reaction progress (AVI), Lead halide perovskite nanoplatelets (LHP NPLs) are of immense interest in the materials science and optoelectronics communities owing to their strong quantum confinement leading to narrow emission peaks, thickness-dependent tunable photoluminescence, and large exciton binding energies. Thus far, their further development and photophysical investigations at ensemble and single-particle levels have been impeded by suboptimal ligand passivation, inferior environmental and colloidal stability compared to their 3D nanocrystal counterparts, and limited compositional diversity. Here, we report highly monodisperse methylammonium lead bromide (MAPbBr3) NPLs (11.3 ± 2.3 × 1.7 ± 0.5 nm) with tunable ligand chemistry and enhanced photoluminescence quantum yields of up to 80%. NPLs capped with zwitterionic ligands exhibit improved stability upon air exposure and sequential purification. Nuclear magnetic resonance spectroscopy on ligand-exchanged NPLs, capped with either phosphocholine- or phosphoethanolamine-type ligands, confirms the partial replacement of the pristine ligands. Owing to the size and shape uniformity of synthesized MAPbBr3 NPLs, they readily form assemblies of stacked face-to-face NPLs, as observed in both colloidal dispersions and films, giving rise to concentration-dependent multicolor emission. The temperature dependence of the NPL emission exhibits a nonmonotonous trend, attributed to the highly anisotropic confinement and the consequent exciton–phonon coupling. We also observed photoluminescence from single MAPbBr3 NPLs at both room and cryogenic temperatures, revealing highly polarized fine-structure emission lines with single-photon purity exceeding 80%. The high uniformity and optical transparency of MAPbBr3 NPL films enabled their integration into optical cavities, where they exhibited strong light-matter coupling with a substantial Rabi splitting of 200 meV., Peer reviewed

Sample preparation, Bloch states and hyperfine interaction in halide perovskites, effective hyperfine coupling constants, pump power dependence measurements, nuclear spin relaxation time expressions and measurements, and Tables S1–S3, Metal halide perovskites have rapidly transformed photovoltaic and optoelectronic research and are increasingly recognized as promising materials for spin-based optical functionalities. Despite this progress, the mechanisms governing spin relaxation in these systems remain insufficiently understood. Here, we demonstrate efficient dynamic nuclear polarization (DNP) in polycrystalline MAPbI3 films, arising from spin flip-flop processes between localized electron and hole spins and the nuclear spin bath. This polarization generates Overhauser fields up to 35 mT for 207Pb nuclei and 15 mT for 127I nuclei, indicating strong coupling with nuclear spin systems. We further show that the DNP building up strongly depends on the orientation of the applied magnetic field, revealing an intrinsic asymmetry of the hyperfine interaction. This behavior is quantitatively captured by a numerical model. These findings unveil a previously unexplored regime of asymmetric hyperfine coupling in halide perovskites and establish a basis for nuclear-assisted control of spin coherence in solution-processed opto-spintronic materials., Peer reviewed

Atmospheric deposition of micro-nutrients like Fe has been shown to be important for ocean biogeochemistry. The largest source of atmospheric Fe and other elements (e.g., Ca, Al, Si, and Ti) is desert dust, although there are significant non-dust sources in some regions (e.g., combustion, sea salts, volcanoes). However, past estimates of these elements have been substantially uncertain due to limited information about the composition of the desert source regions. Here we use elemental distributions estimated from new Earth Surface Mineral Dust Source Investigation (EMIT) observations, which provide mineralogical composition at the surface of the Earth based on imaging spectroscopy measurements from the International Space Station. We focus on total elemental amounts, not on the soluble fraction. We add in other sources of these elements (anthropogenic and natural) and compare to a compilation of available surface concentration data from stations over land and from shipborne observations. The combined observational and model synthesis provides new information about the distribution and deposition of these elements. Our results suggest that the modeled distribution is similar to available observations, but discrepancies still exist in both natural desert dust regions as well as regions dominated by anthropogenic sources. Comparisons between the model estimated Ca/Al ratios and observations in some dust dominated regions suggest an underestimate of Ca/Al ratios. Global budgets for Ca, Al, Fe, Si, and Ti suggest that desert dust remains the dominant source, although volcanic and anthropogenic contributions are important in some regions. Changes in elemental distributions since preindustrial times were also estimated., Peer reviewed

Comparison between the relaxation time distribution (Figure S1), comparison between the gaussian distribution of activation energies (Figure S2); dielectric relaxation data (Figure S3); dielectric relaxation curves (Figure S4); heat capacity change for PCL70k (Figure S5)., Peer reviewed

Te300-Cumdos_iter-0030.dat Te300-Hallfsurf_iter-0030.dat Te300-Ohmic_iter-0030.dat Te_right300-emcha_fsurf_iter-0030.dat Te_right300-NLDO_iter-0030.dat Te_right300-NLDS_iter-0030.dat, Peer reviewed

In the supplemental material we provide a more detailed schematic that shows the workflow of the method described in the main text, and we provide extra useful computational details for the calculations performed., No

This folder contains the relevant input files and data to reproduce the results reported in the manuscript "Optical spatial dispersion via Wannier interpolation" by Andrea Urru, Ivo Souza, Oscar Pozo Ocana, Stepan S. Tsirkin, and David Vanderbilt., U.S. National Science Foundation, Peer reviewed

This dataset contains the raw data supporting the study of converting cashew apple bagasse into ultralight cellulose cryogels and assessing how defatting pre-treatment affects the structure–property relationship. The data include alkaline extraction results (cellulose content of 70–74%), structural analyses (FTIR and XRD with crystallinity indices of 46–48%), and thermal stability profiles (TGA). They also include physical property measurements such as extremely low densities (0.018–0.020 g cm-3), microstructural analyses (CLSM and SEM), mechanical stiffness, and fluid sorption capacities (water and up to 36 mL g-1 for oil). These data support the conclusion that cashew apple bagasse is a promising, sustainable resource for producing advanced porous biomaterials., National Council for Scientific and Technological Development (CNPq, Brazil) [grant number 302451/2021-8]. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil) [Finance Code 001] São Paulo Research Foundation (FAPESP, Brazil) [grant numbers 2023/02064-8, 2024/21147-4, 2024/10205-3, and 2018/14938-4]. Project PID2023-146557OB-C22 was funded by MICIU/AEI/10.13039/501100011033 European Regional Development Fund (ERDF) "A way of making Europe". The EVOLVEPACK project (Innovative Sustainable Packaging to Safeguard Our Food and Our Planet) is part of the PRIMA program, funded by the European Union’s Horizon 2020 research and innovation program and the national research funding agency (PCI2024-153409). Financial support from the Severo Ochoa Centre of Excellence accreditation (CEX2021-01189-S) funded by MCIN/AEI/10.13039/501100011033, With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2021-001189-S)., Peer reviewed

Additional experimental details on electrode preparation, cell configuration, analytical results, and efficiency calculations, additional results: EDX analysis, EPR spectroscopy, and XRD analysis, and additional results of galvanostatic and cycling tests, Electrochemical ammonia synthesis from nitrate can complement a hydrogen-based energy system with a liquid, shippable energy carrier. Ammonia (NH3) is attractive because it serves both as an energy vector and as an essential feedstock. However, nitrate reduction is an eight-electron, proton-coupled pathway that forms multiple intermediates; the NO3– → NO2– step is widely viewed as rate-determining, followed by nitrite reduction and hydrogenation steps, until the formation of NH3. Here, we implement a tandem strategy in a flow cell using a double-sided electrode with Cu and TiO2@Cu surfaces that cooperatively boost the NO3– → NO2– and NO2– → NH3 conversions. The system achieves a Faradaic efficiency toward NH3 of 97%, with an NH3 selectivity of 80%, and a productivity of 7.7 mg h–1 cm–2 (0.45 mmol h–1 cm–2), corresponding to a full-cell energy efficiency of 29%. This integrated electrode–reactor design expands the accessible performance space for the NO3RR by combining nitrate adsorption with selective nitrite hydrogenation. These results establish a practical route for the efficient electrochemical synthesis of NH3 from nitrate., Peer reviewed