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Lignin nanoparticles (LNPs) are promising renewable nanomaterials with applications ranging from biomedicine to water purification. However, the instability of LNPs under acidic and basic conditions severely limits their functionalization for improved performance. Here, we show that controlling the degree of esterification can significantly improve the stability of lignin oleate nanoparticles (OLNPs) in acidic and basic aqueous dispersions. The high stability of OLNPs is attributed to the alkyl chains accumulated in the shell of the particle, which delays protonation/deprotonation of carboxylic acid and phenolic hydroxyl groups. Owing to the enhanced stability, acid‐ and base‐catalyzed functionalization of OLNPs at pH 2.0 and pH 12.0 via oxirane ring‐opening reactions were successfully performed. We also demonstrated these new functionalized particles as efficient pH‐switchable dye adsorbents and anticorrosive particulate coatings., Lignin oleate nanoparticles (OLNPs) are demonstrated for functionalization in aqueous dispersion under acidic (pH 2) and basic (pH 12) conditions owing to the hydration barrier effect provided by oleic acid chains in the shells of OLNPs. Covalent functionalization of these nanoparticles using robust chemistries opens new avenues such as functional anticorrosive coatings and pH‐switchable adsorbents for removal of organic dyes from wastewater.

Breaking down lignin into smaller units is the key to generate high value-added products. Nevertheless, dissolving this complex plant polyphenol in an environment-friendly way is often a challenge. Levulinic acid, which is formed during the hydrothermal processing of lignocellulosic biomass, has been shown to efficiently dissolve lignin. Herein, levulinic acid was evaluated as a medium for the reductive electrochemical depolymerization of the lignin macromolecule. Copper was chosen as the electrocatalyst due to the economic feasibility and low activity towards the hydrogen evolution reaction. After depolymerization, high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy revealed lignin-derived monomers and dimers. A predominance of aryl ether and phenolic groups was observed. Depolymerized lignin was further evaluated as an anti-corrosion coating, revealing enhancements on the electrochemical stability of the metal. Via a simple depolymerization process of biomass waste in a biomass-based solvent, a straightforward approach to produce high value-added compounds or tailored biobased materials was demonstrated.

Sunlight can be used to split water into hydrogen and oxygen by means of a photoelectrochemical (PEC) cell. Oxide nanostructures in heterojunction geometry, consisting of anisotropic WO3 nanostructures coated with a second narrower bandgap semiconductor, such as α-Fe2O3, have emerged as prospective photoanodes. We report on the integration of monodisperse CoPd nanocrystals (NCs) with α-Fe2O3 and WO3/α-Fe2O3 heterojunction semiconductor nanostructures for PEC water oxidation. Depositing CoPd NCs on the surface of hematite leads to more stable photocurrents in comparison to the bare electrode, which indicates improved electron-hole separation at the semiconductor-electrolyte interface. Altering the surface of WO3/α-Fe2O3 photoanodes with CoPd NCs induces a cathodic shift of the onset potential and increases photocurrent density from 0.15 to 0.5 mA cm-2 during water oxidation at 1.23 V vs. RHE under AM 1.5 G illumination (pH 7).

The ternary Zintl phase EuMgGe was synthesized from the elements, and its structure solved by single-crystal X-ray diffraction. Chemical bonding is discussed, by means of electronic structure calculations at the DFT level and its physical properties characterized with respect to electronic conductivity, magnetic susceptibility, specific heat capacity, and magnetoresistivity. The compound may be interpreted according to the Zintl-Klemm concept as (Eu2+)(Mg2+)(Ge4–) with isolated germanium anions. Resistivity measurements reveal a semimetallic character, which is consistent with the vanishing energy gap obtained from our calculations. The magnetic susceptibility and the specific heat indicate that two consecutive transitions take place, at 9 and 16 K, and they show evidence of magnetic frustration. A possible physical scenario for this magnetic behavior is discussed based on known models of partially frustrated magnets.

Zintl phases: The new lithium-rich Zintl phase Li12Ag1−xSi4 (x=0.15) contains the highly charged 16-electron anion [AgSi2]7−. Chemical bonding is discussed based on electronic band structure analysis (see figure).

Two new ternary compounds Eu5+xMg18–xGe13 (x = 0.1) and Eu8Mg16Ge12 were obtained by solid state synthesis and their crystal structures determined by single crystal X-ray diffraction. The two compounds crystallize in the hexagonal crystal system (space group P2m). Eu5+xMg18–xGe13 (x = 0.1) is a Zintl phase with nine isolated Ge4– ions and a [Ge4]10– star, which is isoelectronic with PF3 but surprisingly almost planar. Eu8Mg16Ge12 contains a [MGe3] (M = Eu, Mg) unit, instead of the [Ge4]10–, and can be described as a salt-like compound, containing 12 “isolated” Ge4– anions. The structural similarity of these two compounds allows to analyze the chemical bonding of different Zintl anions, which belong to a structural greater isosteric unit. The metallic conductivity of Eu8Mg16Ge12 originates from the ecliptic stacking of the “so-called isolated” anions along the c direction. In Eu5+xMg18–xGe13 the deviation of the Zintl anion from the planarity causes a semi-metallic behavior. In both cases, the magnetic response is dominated by the local moments of the europium atoms, which are all found in a 2+ oxidation state. Deviations from the Curie–Weiss law are observed for T < 20 K in the cation-richer compound and at lower temperatures in the other. The behavior in the low-temperature range changes with the replacement of the [Ge4]10– star by the MGe3 unit. These studies show that metallic behavior through ecliptic stacking of planar anions can be achieved even with monatomic anions, up to 4.4 A with germanium at least, and can be destroyed by small deviations from planarity in an extended anion.

Jede Menge Lithium: Die Silicide Li7CuSi2, mit dem linearen Zintl-Anion [Si-Cu-Si]7− (siehe Bild), und Li7.3CuSi3 sind die Verbindungen mit dem hochsten Lithiumgehalt in diesem ternren System. Die Kristallstrukturen und Bindungsverhltnisse beider Verbindungen werden besprochen.

The new compounds Li7CuSi2 (I) and Li7.3CuSi3 (II) are synthesized from the elements (Nb ampule, 600 °C, 7 d) and characterized by XRD, magnetic measurements, and band structure calculations.

Eu5.1Mg17.9Ge13 (I) and Eu8Mg16Ge12 (II) are prepared by solid state reaction of the elements (Nb ampules, 890—1020 °C, 48 h—16 d).

The title compound is synthesized by solid state reaction of the elements (Nb ampule, 1020 °C, 48 h followed by 850 °C for 5 d) and characterized by single crystal XRD, magnetic, electrical resistivity, and specific heat measurements, and DFT electronic structure calculations.