Experimental and density functional theory study of the Li+ desorption in spinel/layered lithium manganese oxide nanocomposites using HCl. (2022). Pulido, Naveas, N.; Martín-Palma, R.; Graber, T.; Brito, I.; Hernández-Montelongo, J.; Manso, M.

28 junio, 2022 -

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The increasing demand for portable electronic devices and batteries has led to a growing interest in Li compounds. Lithium manganese oxides (LMO) are the most popular lithium-ion sieves (LIS) precursor materials due to their high lithium adsorption capacity and selectivity. The key step in forming LIS is the lithium desorption process from the crystalline lattice of the LMO. However, this process has been less researched than its counterpart, the lithium adsorption process. In this line, there are some studies describing the process of lithium desorption in acid media from spinel-type LMO. Nevertheless, there is no evidence of the lithium desorption process of layered-type lithium-rich LMO in acidic media. In the present work, we investigated the lithium desorption behavior of different LMO nanocomposites in HCl. LMOs with different Li/Mn ratios were synthesized by promoting the lithium-rich layered phase (Li₂MnO₃). The morphology, size, crystallinity, chemical composition, and surface properties of LMO nanocomposites and delithiated products were studied. In addition, density functional theory (DFT) calculations were carried out to understand the differential lithium desorption behavior, confirming its dependence on the Li/Mn ratio of the LMO nanocomposites. Herein, we demonstrate that the lithium diffusion energy barrier plays a major role during lithium desorption from LMO nanocomposites. Our results suggest that an exhaustive characterization of lithium precursor materials (LMO) is necessary to select a suitable desorption process.

Keywords: Lithium desorptionLithium manganese oxideLi2MnO3Lithium ion-sievesDensity functional theoryNudged elastic band.

Covellite nanoparticles with high photocatalytic activity bioproduced by using H2S generated from a sulfidogenic bioreactor. (2022). Nancucheo, I.; Segura, A.; Hernández, P.; Hernández-Montelongo, J.; Pesenti, H.; Arranz, A.; Benito, N.; Romero-Sáez, M.; Contreras, B.; Díaz, V.; Recio-Sánchez, G..

1 junio, 2022 -

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The application of sulfate reducing bacteria (SRB) has emerged as an efficient biotechnology to reduce sulfate to sulfide and to mediate the precipitation of transition metals as sulfides. In the present work, hydrogen sulfide biogenerated by the SRB was delivered into a copper aqueous solution vessel to produce copper sulfide nanoparticles. The main physico-chemical properties were studied by TEM, XRD, UV–vis spectroscopy, fluorescence spectroscopy, UPS and XPS. In addition, the photocatalytic activities for organic dyes removal were investigated, showing a high degradation rate of MB and RD in aqueous solution. By changing the copper concentration during the synthesis process, main physico-chemical properties of copper sulfides nanoparticles can be controlled. For the lowest concentration, pure covellite flake-like nanostructures were produced. Higher concentrations produced spherical-like shapes with the presence of SO42− on the surface. Experimental results showed a promising way to obtain valorous copper sulfides nanoparticles by using dissimilatory reduction of sulfate mediated by SRB.

Keywords: CuS nanoparticlesPhotocatalytic activitySulfate reduction bacteriaBioreactor