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This mini-review focuses on up-to-date advances of hybrid materials consisting of organic and inorganic components and their applications in different chemical processes. The purpose of forming such hybrids is mainly to functionalize and stabilize inorganic supports by attaching an organic linker to enhance their performance towards a target application. The interface chemistry is present with the emphasis on the sustainability of their components, chemical changes in substrates during synthesis, improvements of their physical and chemical properties, and, finally, their implementation. The latter is the main sectioning feature of this review, while we present the most prosperous applications ranging from catalysis, through water purification and energy storage. Emphasis was given to materials that can be classified as green to the best in our consideration. As the summary, the current situation on developing hybrid materials as well as directions towards sustainable future using organic-inorganic hybrids are presented.

Lithium-ion batteries (LIBs) play a key role in today’s energy storage sector, finding applications in everyday use electronic devices, like smartphones, laptops or electric vehicles. Despite very good properties, such as high electric capacity and high number of charge-discharge cycles, eventually each battery in the world will be disposed and stored in a landfill, waiting for the opportunity to be recycled. Until then, spent LIBs are a serious hazard to the natural environment because of their toxic constituents, like organic electrolytes or transition metal based electrodes, and unfortunately, the majority of those used batteries will never be recycled due to a lack of profitable and sustainable methods for the recovery of battery components. The demand for the production of new batteries is caused by the increase in the number of electronic devices being sold to end customers every year, and battery waste is an important and promising source of valuable metals, so far essential for manufacturing new electrode materials. However, the existing industrial methods for the recovery of metals from batteries, despite high yields and purity of obtained products, usually are associated with high energy demand, implementation or in situ generation of toxic chemicals, and generation of additional, non-recyclable fractions – therefore they can not be considered as sustainable. This thesis summarizes the approaches taken during Author’s doctoral studies towards green LIBs recycling, implementing various techniques, like adsorption and electrochemistry, as well as the valorisation of spent LIBs towards environmental applications. The first and second works implement adsorption for the recovery of metal ions present in the battery cathode materials from aqueous solutions. The third work implements the production of a cobalt catalysts made from scrap LIBs cathode materials with further testing towards hydrogen evolution reaction from sodium borohydride. The fourth work implemen

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.

We report the first magic-angle spinning (MAS) nuclear magnetic resonance (NMR) study on Sn(NCN). In this compound the spatially elongated (NCN)(2)- ion is assumed to develop two distinct forms: either cyanamide (NEC-N2-) or carbodiimide (N-=C=N-). Our N-14 MAS NMR results reveal that in Sn(NCN) the (NCN)(2-) groups exist exclusively in the form of symmetric carbodiimide ions with two equivalent nitrogen sites, which is in agreement with the X-ray diffraction data. The N-14 quadrupolar coupling constant vertical bar C-Q vertical bar approximate to 1.1 MHz for the N-=C=N- ion in Sn(NCN) is low when compared to those observed in molecular compounds that comprise cyano-type N C- moieties (vertical bar C-Q vertical bar > 3.5 MHz). This together with the information from N-14 and C-13 chemical shifts indicates that solid-state NMR is a powerful tool for providing atomic-level insights into anion species present in these compounds. The experimental NMR results are corroborated by high-level calculations with quantum chemistry methods.

The growing demand for Li-ion batteries (LIBs) has made their postconsumer recycling an imperative need toward the recovery of valuable metals, such as cobalt and nickel. Nevertheless, their recovery and separation from active cathode materials in LIBs, via an efficient and environmentally friendly process, have remained a challenge. In this work, we approach a simple and green method for the selective separation of nickel ions from mixed cobalt-nickel aqueous solutions under mild conditions. We discovered that the bioinspired microporous metal-organic framework (MOF) SU-101 is a selective sorbent toward Ni2+ ions at pH 5-7 but does not adsorb Co2+ ions. According to the Freundlich isotherm, the adsorption capacity toward Ni2+ reached 100.9 mg.g(-1), while a near-zero adsorption capacity was found for Co2+ ions. Ni2+ removal from aqueous solutions was performed under mild conditions (22 degrees C and pH 5), with a high yield up to 96%. The presence of Ni2+ ions adsorbed on the surface of the material has been proven by solid-state H-1 nuclear magnetic resonance spectroscopy. Finally, the separation of Ni2+ from Co2+ from binary solutions was obtained with approximately 30% yield for Ni2+, with a near-zero adsorption of Co2+, which has been demonstrated by UV-vis spectroscopy. The ion adsorption process of Ni2+ and Co2+ ions was additionally studied by means of classical molecular dynamics calculations (force fields), which showed that the Ni2+ ions were more prone to enter the MOF canals by replacing some of their coordinated water molecules. These results offer a green pathway toward the recycling and separation of valuable metals from cobalt-containing LIBs while providing a sustainable route for waste valorization in a circular economy.

Efficient and sustainable recycling of cobalt(II) is of increasing importance to support technological development in energy storage and electric vehicle industries. A composite material based on membrane-filtered lignin deposited on nanoporous silica microparticles was found to be an effective and sustainable sorbent for cobalt(II) removal. This bio-based sorbent exhibited a high sorption capacity, fast kinetics toward cobalt(II) adsorption, and good reusability. The adsorption capacity was 18 mg Co(II) per gram of dry adsorbent at room temperature (22 degrees C) at near-neutral pH, three times higher than that of the summarized capacity of lignin or silica starting materials. The kinetics study showed that 90 min is sufficient for effective cobalt(II) extraction by the composite sorbent. The pseudo-second-order kinetics and Freundlich isotherm models fitted well with experimentally obtained data and confirmed heterogeneity of adsorption sites. The promising potential of the lignin-silica composites for industrial applications in the cobalt recovering process was confirmed by high values of desorption in mildly acidic solutions.

We disclose that glycine functionalized silica particles (SiO2-Gly) are highly effective sorbents for the removal of Co(II) and Ni(II) ions from aqueous solution. SiO2-Gly can be prepared from commercial silica gel in a high yielding two step synthesis, and features a glycine concentration of 0.63 mmol.g(-1) (27 mmol.cm(-2)). This material can recover up to 2.81 mmol.g(-1) of Co(II) ions or 3.02 mmol.g(-1) of Ni(II) ions from aqueous solution, a capacity which is tenfold higher than unmodified silica and comparable to the best performing sorbents reported in the literature. These sorption capacities are superstoichiometric in relation to the concentration of glycine on the surface. Sorption of cobalt(II) was improved by addition of ammonia to leaching solutions to give rise to more readily absorbed cobalt amine complexes. Regeneration of sorbent was investigated by desorption of adsorbed metals under mildly acidic solutions, and efficient desorption was noted for both metals. To probe the mechanism of sorption, a thorough characterization campaign involving TGA, FTIR, nitrogen adsorption/desorption, SEM, solid state NMR, solid state UV-Vis-NIR, -COOH titration and pH(pzc) - pH drift methods was undertaken. Our mechanistic study indicated that adsorption was mediated by electrostatic interaction.

Cobalt-based Li-ion batteries are produced globally on a massive scale, but most are discarded to landfill at the end of their useful lifetime. In this work, an efficient cobalt catalyst for the hydrolysis of sodium borohydride to dihydrogen was prepared from lithium ion battery waste, providing a second life for valuable minerals. This material is composed of a mixed metal cobalt-aluminium oxide supported on graphene, as elucidated by a combined FTIR, Raman, SEM, scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) and energy-dispersive X-ray spectroscopy (EDS) study. The obtained metal oxide material, which exhibits an average oxidation state for Co of 2.45, is a languid catalyst at room temperature, but rapid hydrogen production of up to 49 L(H-2) min(-1) g(-1)(Co) was observed in catalytic runs heated to 70 degrees C. This carbon-supported cobalt catalyst is competitive with designed cobalt nanostructured catalysts prepared from pure precursors. This work is illustrative of the opportunities which arise when e-waste is utilised as a mineral resource within the scope of a circular economy.

Lignin is a renewable biopolymer, and its chemical functionalization renders it a prospective material for a plethora of applications. Within this respect, we present a method for lignin immobilization on the surface of mesoporous silica. Two types of lignins were used to prove the feasibility of the fabrication of either hydrophilic or hydrophobic biocoatings on silica. The procedure permits to immobilize 17 mg of lignosulfonate (LS) or 37 mg of kraft lignin (KL) per gram of silica. The bioinorganic composites display a synergistic effect in the adsorption of cobalt(II) ions from aqueous solutions because the adsorption efficiency outperforms the individual constituents. These results demonstrate that thin lignin overlayers, exhibiting polymer concentrations of 0.07 mg.m(-2) for LS-SiO2, and 0.14 mg.m(-2) for KL-SiO2, provide new functionality in comparison to bulk lignin and metal oxides. According to the Langmuir isotherm model, the adsorption capacity toward aqua complexes of Co(II) was found to be 75 and 59 mg.g(-1) for the LS- or KL-coated silica, respectively. The kinetic study revealed that lignin-SiO2 composites gained the features of inorganic sorbents because 1-1.5 h was sufficient for effective cobalt extraction. The adsorption on the bioinorganic composites proceeds with the pseudo-second-order kinetics model. The adsorption of Co(II) ions was confirmed by means of solid-state H-1 magic-angle spinning (MAS) NMR spectroscopy. The simplicity of the synthesis, low-cost and abundancy of substrates, high capacity, and fast kinetics make such lignin-coated silica a promising material for cobalt recovery.