Publications by authors named "Pablo A Aparicio"

Understanding the surface reactivity of the commercial cathode material LiMnO towards the electrolyte is important to improve the cycling performance of secondary lithium-ion batteries and to prevent manganese dissolution. In this work, we have employed spin-polarized density functional theory calculations with on-site Coulomb interactions and long-range dispersion corrections [DFT+U-D3-(BJ)] to investigate the adsorption of the electrolyte component ethylene carbonate (EC) onto the (001), (011) and (111) surfaces of the fully lithiated and partially delithiated LiMnO spinel (0.000 < x < 0.

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Sodium-ion batteries are considered one of the most promising alternatives to lithium-ion batteries owing to the low cost and wide abundance of sodium. Phosphate compounds are promising materials for sodium-ion batteries because of their high structural stability, energy densities and capacities. Vanadium phosphates have shown high energy densities, but their sodium-ion diffusion and cation doping properties are not fully rationalized.

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Article Synopsis
  • Researchers synthesized eight new mixed-metal polyoxometalates (POMs) with amino acid ligands, maintaining a consistent structural framework while varying the central metal-oxo core's nuclearity, redox state, and metal composition.
  • Structural studies showed that molybdenum (Mo) preferentially occupies the central core, which forms different structural patterns depending on its oxidation state: a closed tetrametallic loop in reduced species and an open trimetallic loop in oxidized forms.
  • Stability tests indicate that these hybrid POMs are stable in aqueous solutions for days, with evidence of amino acid exchange without altering the POM structure, though reduced and oxidized forms are not inter
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The first members of a promising new family of hybrid amino acid-polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium-tungstoarsenate structural backbone, followed by crystallization with p-methylbenzylammonium (p-MeBzNH3(+)) cations, affords (p-MeBzNH3)6K2(GlyH)[As(III)4(Y(III)W(VI)3)W(VI)44Y(III)4O159(Gly)8(H2O)14]⋅47 H2O (1) and enantiomorphs (p-MeBzNH3)15(NleH)3[As(III)4(Mo(V)2Mo(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11][As(III)4(Mo(VI)2W(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11] (generically designated 2: L-Nle, 2 a; D-Nle, 2 b). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site-selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions.

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Polyoxometalates (POMs) are inorganic entities featuring extensive and sometimes unusual redox properties. In this work, several experimental techniques as well as density functional theory (DFT) calculations have been applied to identify and assess the relevance of factors influencing the redox potentials of POMs. First, the position of the Mo substituent atom in the Wells-Dawson structure, α1- or α2-P2W17Mo, determines the potential of the first 1e(-) reduction wave.

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The radioactive element technetium-99 ((99)Tc, half-life = 2.1 × 10(5) years, β(-) of 253 keV), is a major byproduct of (235)U fission in the nuclear fuel cycle. (99)Tc is also found in radioactive waste tanks and in the environment at National Lab sites and fuel reprocessing centers.

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The unusual redox behavior displayed by the two isomers of the Wells-Dawson phosphotungstate anion [Fe(H(2)O)P(2)W(17)O(61)](7-) is presented. The electrochemical measurements have been performed in aqueous media at different pH values from 0.5 up to 8.

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The [ε-PMo(V)(8)Mo(VI)(4)O(36)(OH)(4){Ln(III)(H(2)O)}(4)](5+) (Ln=La, Ce, Nd, Sm) polyoxocations, called εLn(4), have been synthesized at room temperature as chloride salts soluble in water, MeOH, EtOH, and DMF. Rare-earth metals can be exchanged, and (31)P NMR spectroscopic studies have allowed a comparison of the affinity of the reduced {ε-PMo(12)} core, thus showing that the La(III) ions have the highest affinity and that rare earths heavier than Eu(III) do not react with the ε-Keggin polyoxometalate. DFT calculations provide a deeper insight into the geometries of the systems studied, thereby giving more accurate information on those compounds that suffer from disorder in crystalline form.

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