In order to effectively practice the Aqueous Lignin Purification with Hot Agents (ALPHA) process for lignin purification and fractionation, the temperatures and feed compositions where regions of liquid–liquid equilibrium (LLE) exist must be identified. To this end, pseudo-ternary phase diagrams for the lignin–acetic acid–water system were mapped out at 45-95 °C and various solvent: feed lignin mass ratios (S:F). For a given temperature, the accompanying SL (solid–liquid), SLL (solid–liquid–liquid), and one-phase regions were also located. For the first time, ALPHA using acetic acid (AcOH)–water solutions was applied to a lignin recovered via the commercial LignoBoost process. In addition to determining tie-line compositions for the two regions of LLE that were discovered, the distribution of lignin and key impurities (the latter can negatively impact lignin performance for materials applications) between the two liquid phases was also measured. As a representative example, lignin isolated in the lignin-rich phase was reduced 7x in metals and 4x in polysaccharides by using ALPHA with a feed solvent composition of 50-55% AcOH and an S:F of 6:1, with said lignin being obtained at a yield of 50-70% of the feed lignin and having a molecular weight triple that of the feed.

Plasma electrolysis of Cu electrodes in P-based electrolytes generates distinct surface structures, including octahedral nanocrystals, besides nanoporous and microporous features. Cu electrodes polarized in Na₂HPO₃ and Na₃PO₄ exhibit high selectivity for C₂ products, establishing in-liquid plasma as an attractive option for developing efficient Cu electrocatalysts for sustainable CO₂ conversion.

Abstract

This study presents a green, ultra-fast, and facile technique for the fabrication of micro/nano-structured and porous Cu electrodes through in-liquid plasma electrolysis using phosphorous-oxoanion-based electrolytes. Besides the preferential surface faceting, the Cu electrodes exhibit unique surface structures, including octahedral nanocrystals besides nanoporous and microporous structures, depending on the employed electrolyte. The incorporation of P-atoms into the Cu surfaces is observed. The modified Cu electrodes display increased roughness, leading to higher current densities for CO₂ electroreduction reaction. The selectivity of the modified Cu electrodes towards C₂ products is highest for the Cu electrodes treated in Na₂HPO₃ and Na₃PO₄ electrolytes, whereas those treated in Na₂H₂PO₂ produce the most H₂. The Cu electrode treated in Na₃PO₄ produces ethylene (23 %) at −1.1 V vs. RHE, and a comparable amount of acetaldehyde (15 %) that is typically observed for Cu(110) single crystals. The enhanced selectivity is attributed to several factors, including the surface morphology, the incorporation of phosphorus into the Cu structure, and the formation of Cu(110) facets. Our results not only advance our understanding of the influence of the electrolyte's nature on the plasma electrolysis of Cu electrodes, but also underscores the potential of in-liquid plasma treatment for developing efficient Cu electrocatalysts for sustainable CO₂ conversion.

Synthesis and analysis of chitosan-based materials with different green additives as a first step towards renewable plastic alternatives. The properties of the films were tunable in a broad range, and the additives could be divided in three different classes depending on their uptake behavior: linear, non-linear, and crosslinking additives.

Abstract

To switch to alternatives for fossil-fuel-based polymer materials, renewable raw materials from green resources should be utilized. Chitosan is such a material that is a strong, but workable derivative from chitin, obtained from crustaceans. However, various applications ask for specific plastic properties, such as certain flexibility, hardness and transparency. With different additives, also obtainable from green resources, chitosan-based composites in the form of self-supporting films, ranging from very hard and brittle to soft and flexible were successfully produced. The additives turned out to belong to one of three categories, namely linear, non-linear, or crosslinking additives. The non-linear additives could only be taken up to a certain relative amount, whereas the uptake of linear additives was not limited within the range of our experiments. Additives with multiple functional groups tend to crosslink chitosan even at room temperature in an acidic medium. Finally, it was shown that dissolving the chitosan in acetic acid and subsequently drying the matrix as a film results in reacetylation compared to the starting chitosan source, resulting in a harder material. With these findings, it is possible to tune the properties of chitosan-based polymer materials, making a big step towards application of this renewable polymer within consumer goods.

Membrane degradation: Proton exchange membrane (PEM) fuel cells convert electrochemical energy into electrical energy. During fuel cell operation reactive oxidizing species are formed that degrade the PEM. We investigated the degradation of a generic aromatic sulfonate-type membrane and its repair by the antioxidant (AO) Cu(II)−porphyrin. We found that the porphyrin AO significantly increases the stability towards radical-induced degradation.

Abstract

The use of hydrocarbon-based proton conducting membranes in fuel cells is currently hampered by the insufficient durability of the material in the device. Membrane aging is triggered by the presence of reactive intermediates, such as HO⋅, which attack the polymer and eventually lead to chain breakdown and membrane failure. An adequate antioxidant strategy tailored towards hydrocarbon-based ionomers is therefore imperative to improve membrane lifetime. In this work, we perform studies on reaction kinetics using pulse radiolysis and γ-radiolysis as well as fuel cell experiments to demonstrate the feasibility of increasing the stability of hydrocarbon-based membranes against oxidative attack by implementing a Nature-inspired antioxidant strategy. We found that metalated-porphyrins are suitable for damage transfer and can be used in the fuel cell membrane to reduce membrane aging with a low impact on fuel cell performance.

For clean water: Based on graphite from spent lithium-ion batteries, the reconstructed graphite porous hydrogel (RG-PH) was successfully prepared by crosslinking foaming technology, which showed a high evaporation rate for desalination under one sunlight irradiation, and effectively removed various organic contaminants in wastewater, including typical volatile organic compound of phenol.

Abstract

Solar-driven interfacial evaporation technology is regarded as an attracting sustainable strategy for obtaining portable water from seawater and wastewater, and the recycle of waste materials to fabricate efficient photothermal materials as evaporator to efficiently utilize solar energy is very critical, but still difficult. To this purpose, graphite recovered from spent lithium-ion batteries (SLIBs) was realized using a simple acid leaching method, and a reconstructed graphite-based porous hydrogel (RG-PH) was subsequently fabricated by crosslinking foaming method. The incorporation of reconstructed graphite (RG) improves the mechanical characteristics of hydrogels and the light absorption performance significantly. The evaporation rate of optimized RG-PH can constantly reach 3.4278 kg m⁻² h⁻¹ for desalination under a one solar irradiation, and it also showed the excellent salt resistance in various salty water. Moreover, RG-PH has a strong elimination of a variety of organic contaminants in wastewater, including the typical volatile organic compound of phenol. This research shows the potential application of flexible and durable solar evaporators made from waste materials in purifying seawater and wastewater, not only contributing to carbon neutrality by recycling graphite from SLIBs, but also ensuring the cost-effectiveness harvest of solar energy for constantly obtaining clean water.

Sustainable covalent adaptable networks (CANs): Vinylogous urethane CANs were developed according to green chemistry principles, from organosolv lignin using solvent-free reactions and non-toxics compounds. Structure-property relationship as well as the vitrimer behavior of the cross-linked materials was fully investigated. The recyclable materials also exhibited healing ability, improving their lifecycle and sustainability.

Abstract

During the two last decades, covalent adaptable networks (CANs) have proven to be an important new class of polymer materials combining the main advantages of thermoplastics and thermosets. For instance, materials can undergo reprocessing cycles by incorporating dynamic covalent bonds within a cross-linked network. Due to their versatility, renewable resources can be easily integrated into these innovative systems to develop sustainable materials, which can be related to the context of the recent development of a circular bioeconomy. Lignins, the main renewable sources of aromatic structures, are major candidates in the design of novel and biobased stimuli-responsive materials such as vitrimers due to their high functionality and specific chemical architectures. In the aim of developing recyclable lignin-based vinylogous urethane (VU) networks, an innovative strategy was elaborated in which lignin was first modified into liquid polyols and then into polyacetoacetates. Resulting macromonomers were integrated into aromatic VU networks and fully characterized through thermal, mechanical, and rheological experiments. Viscoelastic behaviors of the different aromatic vitrimers exhibited fast stress-relaxations (e. g., 39 s at 130 °C) allowing easy and fast mechanical reprocessing. A thermomechanical recycling study was successfully performed. Then, the developed strategy enabled the fabrication of healable biobased aromatic vitrimers with tunable structures and properties.

Lattice strain engineering optimizes the interaction between the catalytic surface and adsorbed molecules by adjusting the electron and geometric structure of the metal site to achieve high electrochemical performance, but it has been rarely reported on anti-poisoned oxygen reduction reaction (ORR) to date. Herein, lattice-strained Pd@PdBiCo quasi core-shell metallic aerogels (MAs) were designed by “one-pot and two-step” method for anti-poisoned ORR. Pd@PdBiCo MAs/C would maintain their original activity (1.034 A mgPd-1) in electrolytes with CH3OH and CO at 0.85 V vs. reversible hydrogen electrode (RHE), outperforming the commercial Pd/C (0.156 A mgPd-1), Pd MAs/C (0.351 A mgPd-1), and PdBiCo MAs/C (0.227 A mgPd-1). Moreover, Pd@PdBiCo MAs/C also show high stability and anti-poisoning with negligible activity decay after 8000 cycles in 0.1 M KOH + 0.3 M CH3OH. These results of X-ray photoelectron spectroscopy, CO stripping, and diffuses reflectance infrared Fourier transform spectroscopy reveal that the tensile strain and strong interaction between different elements of Pd@PdBiCo MAs/C effectively optimize electronic structure to promote O2 adsorption and activation, while suppressing CH3OH oxidation and CO adsorption, leading to high ORR activity and anti-poisoning property. This work inspires the rational design of MAs in fuel cells and beyond.

The proposal of synthesizing benzyl skeleton derivatives via direct oxidation of functionalized benzylic C–H bonds has received extensive research attention. Herein, a method was developed to prepare carbonyl compounds via photoinduced aerobic oxidation of ubiquitous benzylic C–H bonds mediated by bromine radicals and tribromomethane radicals. This method employed commercially available CBr4 as a hydrogen atom transfer reagent precursor, air as an oxidant, water as a reaction solvent, and tetra-butylammonium perchlorate (TBAPC) as an additive under mild conditions. A series of substrates bearing different functional groups was converted to aromatic carbonyls in moderate to good yields. Moreover, a low environmental factor (E-factor value = 0.45) showed that the proposed method is ecofriendly and environmentally sustainable.

Lithium-sulfur (Li-S) batteries show advantage of high theoretical capacity. However, the shuttle effect of polysulfides and sluggish sulfur redox kinetics seriously reduce their service life. Inspired by the porous structural features of biomass materials, herein, a functional interlayer is fabricated by silkworm excrement-derived three-dimensional porous carbon accommodating nano sized CoS2 particles (SC@CoS2). The porous carbon delivers a high specific surface area, which provides adequate adsorption sites, being responsible for suppressing the shuttle effect of polysulfides. Meanwhile, the porous carbon is favorable for hindering the aggregation of CoS2 and maintaining its high activity during extended cycles, which effectively accelerates the polysulfides conversion kinetics. Moreover, the SC@CoS2 functional interlayer effectively restrains the formation of Li dendrites and promotes the uniform deposition of Li on the Li electrode surface. As a result, the CMK-3/S cathode achieves a high initial capacity of 1599.1 mAh g-1 at 0.2 C rate assisted by the polypropylene separator coated with the functional interlayer and 1208.3 mAh g-1 is maintained after the long cycling test. This work provides an insight into the designing of long-lasting catalysts for stable functional interlayer, which encourages the application of biomass-derived porous carbon in high-energy Li-S batteries.

Mechanochemical synthesis of corannulene by ball milling technique is shown to be a highly efficient and scalable process. Through this method, 15 g of corannulene could be obtained in a single milling cycle in 90 % isolated yield.

Abstract

Corannulene, a curved polycyclic aromatic hydrocarbon, is prepared in a multigram scale through mechanochemical synthesis. Initially, a mixer mill approach is examined and found to be suitable for a gram scale synthesis. For larger scales, planetary mills are used. For instance, 15 g of corannulene could be obtained in a single milling cycle with an isolated yield of 90 %. The yields are lower when the jar rotation rate is lower or higher than 400 revolutions per minute (rpm). Cumulatively, 98 g of corannulene is produced through the ball milling-based grinding techniques. These results indicate the future potential of mechanochemistry in the rational chemical synthesis of highly curved nanocarbons such as fullerenes and carbon nanotubes.