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As a new type of green photothermal material, lignin exhibits an excellent photothermal effect due to its abundant aromatic rings and π–π conjugated structure. To develop value-added applications of lignin in the photothermal field, it is important to explore strategies for regulating the photothermal conversion of lignin. In this work, the photothermal effect of lignin was improved significantly through modification with an electron-withdrawing group. The introduction of acetyl resulted in the formation of an electron donor–acceptor (D–A) structure in lignin and enhanced the light absorption ability. The intermolecular interaction among lignin molecules also decreased after modification with acetyl groups, leading to enhanced non-radiative decay induced by molecular motion. Under 808 nm laser irradiation at 0.51 W cm−2, the photothermal conversion efficiency of acetylated lignin (ACAL) reached as high as 73.2%, which was 37% higher than that of unmodified lignin. This study provides a new strategy to enhance the photothermal effect of lignin and deepens the understanding of the lignin photothermal mechanism. [ABSTRACT FROM AUTHOR]

Thermoplastic starch (TPS) has acquired considerable attention and many efforts have been devoted to its application in many areas, such as food packaging, waterborne coatings, gas barriers, and energy storage and generation. Differing from other thermoplastic polymers, the manufacturing of TPS requires appropriate solvents for granule disruption, which contribute to the dissociation of the double helical structure of starch granules and the reconstitution of hydrogen bond crosslinking between solvent molecules and starch chains. Today, state-of-the-art approaches and techniques are commonly found in literature. However, in many cases, there is no clear definition or guidelines on what aspects are involved and what roles hydrogen bonds play in the synthesis of TPS. This review focuses on classifying, differentiating, and correlating the existing concepts using recent literature reports to provide readers with a general insight into the thermodynamic and kinetic aspects of TPS green manufacturing. Moreover, this review summarizes the potential of green solvents and green polymers to prepare TPS-based materials for fighting against post-consumer waste and expanding their application sphere. Furthermore, next generation TPS, multifunctional starch organic gel, and its fabrication strategies and applications in power sources for wearable electronics as well as efficient energy storage and multimodal stimulus-responsive sensors are elaborated in this review. Eventually, a good comprehension of suggestions and outlooks concerning the applications of TPS-based materials presented would contribute to the development of new complex, functional materials. [ABSTRACT FROM AUTHOR]

This tutorial review aims to describe the status of the scaling up of organosolv treatment. It is a process where various lignocellulosic materials are fractionated, selective depolymerization mechanisms are catalyzed, and their main components (polysaccharides, lignin and extractives) can be extracted, separated and isolated using liquid organic solvents such as alcohols, ketones and proton-donating acid molecules. Organosolv fractionation can be applied to several renewable biomasses, allows the production of pure species systems to prepare valuable chemicals, polymers and biomaterial compositions with a related environmental impact, lower than that of classical industrial plants, and optimizes the resource carbon efficiency. However, the high energy consumption for the recovery after dissolution, input costs and feedstock flexibility robustness are slowing down the piloting of commercial operations. As a critical indicator evaluation, a summary of reasons why engineering organosolv is still extremely interesting, together with an overview of the most important organosolv technologies, describing current equipment scale range economics, limitations and market research opportunities, is presented in detail. A variety of sources (wood, straw, bagasse, wastes...), media (water, methanol, ethanol, formates, acetates...) and products (biogas, bioethanol, (nano)cellulose, glucose, furans...) are comparatively benchmarked. Existing (model) validated, demonstrational or patented configurations are collected, listing strengths as well as challenges. [ABSTRACT FROM AUTHOR]

Polyelectrolytes with ultra-low glass transition temperatures (Tg) are still a rarity. Herein, we report a series of free-flowing lignin polyelectrolytes with ultra-low Tg in the range of −57–9 °C, namely, deep eutectic supramolecular lignin (DESL). The enabling key principle is to couple the eutectic strategy with supramolecular polymerization, bypassing the exclusive reliance on the large size and flexible cation/anion pairs for flowable polyelectrolytes. Following this principle, various sugars have been successfully integrated with lignosulfonic acid via multiple hydrogen bondings, allowing for bulk yet free-flowing supramolecular materials. These DESLs are processible, adaptive, and compatible to serve as macromolecular solvents and are distinct from traditional polyelectrolyte solutions or chemical modification derivatives. The robustness and versatility of our approach provide a fresh opportunity for booming polyelectrolyte utilization, opening access to a yet unknown fluidic material class. [ABSTRACT FROM AUTHOR]

Developing green and effective solvents is of significant importance for the utilization of lignin. Here, we demonstrated that biomass-derived polar aprotic solvents can serve as co-solvents with poly-deep eutectic solvents (PDESs) for massively dissolving various lignin samples at room temperature. The pristine PDESs were composed of polyethylene glycol derivatives and levulinic acid, while all of them exhibited poor solubility to enzymatic hydrolysis lignin (EHL), sodium lignosulfonate (LS), and organosolv lignin (OL). With the further introduction of polar aprotic solvents, including dimethylisosorbide (DMI), dihydrolevoglucosenone (Cyrene), N-formylmorpholine (NFM), and propylene carbonate (PC), synergy between the polar aprotic solvents and PDESs dramatically increased lignin solubility to 96.82%. PC and DMI were more suitable for assisting the solubilization of EHL and OL, while Cyrene and PC were targeted at the solubilization of LS in PDESs, respectively. Moreover, a new unified co-solvent solubilization mechanism relative to the Kamlet–Taft empirical parameters was proposed. The novel polar aprotic/PDES systems provide a new avenue for boosting the high utilization of lignin. [ABSTRACT FROM AUTHOR]

Developing aqueous stable and catalytic Ti3C2Tx MXene suspensions remains a grand challenge. MXene nanosheets always undergo rapid degradation when exposed to water and oxygen, and the incorporation of reducing or capping agents may deteriorate the intrinsic characteristics of MXenes. Here, we coupled dialdehyde xylan (DAX) with MXene nanosheets to significantly increase the long-term storage of MXene in an aqueous solution (>3 months) with a dramatic enhancement of their room temperature catalytic activity for ultrafast gelation. DAX can form thick and smooth layers on the nanosheets via multiple hydrogen bonds, providing a reduction environment to prevent the occurrence of oxidation. Meanwhile, DAX can accelerate the generation of free radicals from the potassium persulfate (KPS)/MXene pair, reducing the polymerization time of vinyl monomers from ∼30 min to ∼90 s. Moreover, the DAX layer is capable of serving as additional crosslinks by leveraging Schiff base bonds with chitosan (CS), with the elongation at break increasing from 100% to 909%. The resultant MXene-based hydrogel can be further explored as a sustainable sensor for real-time physical signal monitoring. This work offers an enticing prospect for the development of eco-friendly and high-performance MXene-based materials. [ABSTRACT FROM AUTHOR]

The high overpotential of the oxygen evolution reaction (OER) and the undesirable chlorine evolution reaction (ClER) severely limit the hydrogen production efficiency of seawater electrolysis. The organic electrooxidation reactions, involving C–H bond oxidation with low bond dissociation energy in the rate-limiting step, can possess lower oxidation potential than the OER as well as prevent the ClER. Herein, we demonstrate a strategy for replacing the sluggish OER by thermodynamically favorable biomass oxidation for scaling up the electrolysis of alkaline seawater. A xylose electrooxidation reaction (XOR) holds great promise for superseding the OER in seawater electrolysis, which not only simultaneously produces valuable formic acid and hydrogen, but also improves energy utilization. By utilizing NiCoP metal phosphide as the bifunctional electrode, the XOR shows an apparent overpotential reduction of 290 mV at 100 mA cm−2 as compared with the OER in the alkaline seawater electrolyte. Furthermore, the xylose-assisted seawater electrolysis exhibits a high formic acid selectivity of at least 94.6% and a high hydrogen production rate of 150 mL cm−2. This work provides a universal and an effective pathway for hydrogen production from seawater and biomass upgrading. [ABSTRACT FROM AUTHOR]

The valorization of abundant agrowastes into chemicals and advanced materials is of key importance in the context of the circular bioeconomy and biorefinery. Herein, we report the ionothermal carbonization (ITC) of sugarcane bagasse, a fibrous residue made of lignocellulose, to engineer advanced carbonaceous materials, namely ionochars. We prepared a series of imidazolium tetrachloroferrate ionic liquids (IL) bearing modular substituents, e.g., alkyl chains with different lengths or benzyl groups. The effect of the cation on both textural and morphological properties is highlighted. Ionochars with high specific surface area (up to 800 m2 g−1), tuneable pore volume (up to 0.8 cm3 g−1), singular nanostructures and adjustable CO2 uptake/retention were obtained. [ABSTRACT FROM AUTHOR]

Carbon reduction targets urge people to develop potential alternatives to traditional energy-intensive kraft pulping. To address this need, this work reported a sustainable pulping technology for eucalyptus slabs based on a deep eutectic solvent (DES) consisting of benzyltriethylammonium chloride (BTEAC) and formic acid (FA). Under mild cooking conditions (T = 130 °C, t = 2.0 h), the pulp yield reached 53.83%, and fibers had a length of 0.65 mm and a fines content of 6.21%. The physical properties of DES pulp were similar to those made by other traditional processes. Meanwhile, approximately 85% of FA and 92% of BTEAC could be reused in the improved chemical recovery process, and the cooking efficiency of recycled DES was largely maintained after 5 times of recycling. Moreover, compared with the kraft process, DES pulping could extract more lignin with high purity and narrow molecular weight distribution. The results proved that this technology could produce high-quality pulp and lignin by-products simultaneously with less energy and chemical consumption. [ABSTRACT FROM AUTHOR]

Blending lignin with industrial degradable polyester is a sustainable and economically competitive strategy for biodegradable plastic production, but the miscibility of the composite remains a great challenge. In this study, the screened lignin with low molecular weight, uniform structure and rich hydroxyl groups was completely miscible with poly(butylene adipate-co-terephthalate) (PBAT). The low molecular weight of ethyl acetate dissolved lignin (EL) was critical for decreasing its glass transition temperature and steric hindrance, and the abundance of functional groups offered plenty of sites for forming strong intermolecular interactions between EL and PBAT. The intermolecular hydrogen bonds and π–π interactions of EL and PBAT promoted the dissociation of the lignin complex, thereby enhancing the plasticizing effect of PBAT on lignin. The PBAT/EL composite film with 50 wt% EL loading (P/EL50) displayed high tensile strength (24.7 MPa) and elongation at break (494.7%), being ahead of the currently reported PBAT composite films with high lignin addition. The yield strength increased threefold due to the rigid lignin structure and the intrinsic multiple noncovalent interactions. Moreover, compared to pure PBAT films, P/EL50 films exhibited a higher sensitivity of the mechanical performance to temperature and had a 22.9% cost reduction. [ABSTRACT FROM AUTHOR]

Engineered lignocellulose valorization enables the formation of superior energy and environmental materials which are developed to achieve the aim of sustainable carbon-neutral technologies. In this work, sequential manufacture under the trigger of hydrothermal fractionation is proposed for the "two-in-one" valorization of wheat straw into highly dispersed Fe, N-codoped carbon spheres (Fe–N–C) and Co nanoclusters anchored on biochar (Co–N–C) via using synchronous pyrolysis/activation. Taking advantage of the ordered ion-diffusion shortcut, suitable geometric/nanosized porous structure, ultrahigh surface area, well-developed packing architecture, and multiple redox possibilities (i.e., Fe species and N functional groups), the durable, conductive Fe–N–C microspheres can function as supercapacitor electrodes, exhibiting superior specific capacitance, rate-performance, and long-cycling lifespan. Benefitting from well-exposed Co nanoclusters and N coordination, the recyclable Co–N–C catalysts enabling efficient persulfate activation are conducive to expediting tetracycline removal with a working pH from 3 to 9, and a concomitant mechanism involving reactive oxygen species and interface electron shuttling is revealed via radical trapping, direct charge-transfer, and theoretical simulation. Hence this work provides multifaceted insights into a coupling strategy for lignocellulose conversion that involves matching the brand-new "biomass–energy–water" interplay with improved biorefining value. [ABSTRACT FROM AUTHOR]

Dehydration of the most relevant biomass derived monosaccharides, xylose, glucose and fructose, was investigated to attain value-added platform chemicals: furfural, hydroxymethylfurfural (5-HMF) and levulinic acid (LA). Reaction kinetics were studied in an aqueous environment in the presence and absence of the H-BEA zeolite. H-BEA demonstrated high activity, especially for isomerization of monosaccharides and rehydration of 5-HMF, while this work demonstrated that dehydration of sugars was governed predominantly by homogeneous reactions. Saccharide reactivity followed the trend of fructose > xylose > glucose, while 5-HMF was more susceptible to further conversion compared to furfural. The addition of H-BEA compromised 5-HMF yields (being an intermediate), and facilitated its further conversion to levulinic acid. The absence of a solid acid catalyst resulted in significant amounts of furfural and 5-HMF, whereas the addition of H-BEA resulted in higher yields of levulinic acid (26 mol% and 30 mol%). Excellent agreement between experimental and modelled values allowed the use of kinetic parameters for predictive modelling and optimization of the process conditions for maximizing the yields of 5-HMF and LA. The optimization was experimentally validated, where homogeneously catalyzed dehydration of fructose resulted in the highest 5-HMF yield (52 mol%) attained in 34 min at 234 °C due to the high activation energy (139 kJ mol−1) and reaction rate constants. In contrast, the highest LA yield was achieved at moderate operational temperatures (165 °C) and longer reaction times (10 h) as a result of a significantly lower energy barrier (60 kJ mol−1) determined for rehydration reactions. [ABSTRACT FROM AUTHOR]

Electrocatalytic overall water splitting is a sustainable method to produce renewable hydrogen energy, but its industrial-scale application is limited by the high energy consumption caused by the high overpotential. Herein, we report the first example of constructing bifunctional cobalt/nitrogen-codoped carbon (CoNC) nanosheet arrays on copper foam (CF) to drive an energy-saving H2 production system with glucose-assisted Cu(I)/Cu(II) redox-looping. A series of size-controllable CoNC nanosheet arrays derived from a ZIF-L precursor are assembled on CF to balance the activity and durability of glucose-assisted Cu(I)/Cu(II) redox-looping and the HER. The optimized CoNC arrays can not only act as a highly-active electrocatalyst of the HER with outstanding electrochemical activity (η10 = 64 mV), but also protect the copper sites of CF from leaching in the glucose-assisted Cu(I)/Cu(II) redox-looping, thus significantly improving the stability of this self-supported electrode. Consequently, a superior energy-saving glucose-assisted system can be assembled by using this bifunctional Cu/CoNC as both the cathode and anode, which exhibits an ultra-low input cell voltage of 0.9 V to achieve 100 mA cm−2 with an ultra-low electricity consumption of 1.97 kW h per cubic meter of H2, much lower than the theoretical value of conventional overall water splitting (1.23 V and 2.7 kW h). [ABSTRACT FROM AUTHOR]

Nowadays, the vigorous development of biomass catalytic valorization is gradually moving towards a promising era. Integrating nitrogen elements into biomass catalytic systems promises more possibilities for upgrading the roadmap of biomass feedstocks. The amination of lignin to cyclohexylamine and its derivatives is a potential alternative to the fossil-based pathway. One-pot catalytic amination of lignin model compounds is challenging and inefficient due to their structural characteristics. Concerning the amination pathway, cyclohexanone and cyclohexanol are important intermediates. Based on this, we discuss the structural preferences of catalysts in the selective hydrogenation process, as well as the amination process of cyclohexanone and cyclohexanol to guide the design of catalysts for the one-pot amination of lignin. Then, the catalytic amination systems are deeply analyzed based on their catalytic conditions. Finally, according to the current development status of lignin amination, the challenges and prospects are proposed for a better lignin valorization. [ABSTRACT FROM AUTHOR]

Catalytic transfer hydrogenolysis (CTH) has emerged as a sustainable and carbon-neutral biorefinery process due to the decrease in the carbon footprint and high atom and energy efficiency. Herein, heteropoly acids (HPAs) as green catalysts were used for the CTH of Kraft lignin (KL) into lignin oil under mild conditions. It is found that all the types of HPAs, Pd/C, H-donor solvent and reaction temperature affected significantly the conversion of Kraft lignin. SiW12 and PW12, respectively, afforded 95.0% and 83.8% KL conversion in isopropanol with Pd/C at 190 °C for 5 h. However, the degradation of eucalyptus Kraft lignin (EKL) provided phenolic monomers with the highest yield of 42.6% using SiW12 and Pd/C. Molecular dynamics (MD) simulation showed that SiW12 and PW12 in isopropanol are more likely to be close to lignin compared to n-propanol. The relative average molecular weight of the obtained lignin oil ranges from 100 Da to 700 Da, including phenolic monomers, dimers and trimers. The lignin monomer products are mainly composed of guaiacols and syringols with 0 to 3 carbon side chains. The simultaneous depolymerization and deoxygenation of KL during CTH led to a high-boiling organic fraction, analyzed with a Fourier transform-ion cyclotron resonance mass spectrometer (FT-ICR MS) equipped with an electrospray negative ion source (ESI−), maintaining highly aromatic structures and having lower O/C and higher H/C ratios compared to initial lignin. This work exhibits a prospective application of the CTH for the conversion of technical lignin to chemicals and biofuels. [ABSTRACT FROM AUTHOR]

Further utilization of furfural residue, an industrial solid waste, has been a long-term challenge because of its hostile properties that limit applications, such as strong acidity and high salinity. Herein, inspired by the pulping technology, an environmentally friendly system was proposed to separate cellulose and lignin from the furfural residue by treatment with formic acid–hydrogen peroxide (FA–H2O2), followed by ultrasound treatment, dilution, and high-speed centrifugation. The three products obtained are nanocellulose, precipitated lignin, and nano-scale lignin. Results showed that the FA–H2O2 system can extract lignin from the furfural residue effectively with high selectivity, but has negligible effect on cellulose extraction from the furfural residue. When the furfural residue (5 g) was treated with 40 mL FA and 16 mL H2O2, the remaining lignin content in the solid residue reached the lowest value (0.8 wt%), and the corresponding cellulose content was 88.0 wt%. The lignin structure obtained by the dilution–precipitation procedure was mainly p-hydroxyphenyl (H) with a molecular weight of 1093–1634 g mol−1, while the nano-scale lignin obtained from the supernatant by centrifugation was an oblate sphere, with a transverse size range of 332–511 nm and a thickness of 2–10 nm. Nanocellulose obtained by ultrasound treatment had a width of 15–55 nm, a length of 500–1000 nm, a zeta potential of −35 mV to −45 mV and a transmittance of 65%–90% at 800 nm. This method simply converts industrial furfural residue waste into high value-added nanoparticles and precipitates lignin, which increases the economic added value of the furfural residue and eliminates its pollution to the environment. [ABSTRACT FROM AUTHOR]

Upgrading renewable lignocellulose into bulk chemicals and drop-in-fuels has been identified as a state-of-the-art paradigm to fulfill alternative energy demands. Lignin, as the largest precursor of alkyl aromatics, can be depolymerized effectively to maneuver task-specific phenols. Toward an ecofriendly lignin-first depolymerization, photocatalytic lignocellulose conversion, also termed photobiorefining, is of utmost importance to boost economic and technical feasibility of holistic biomass valorization. It is still an urgent but challenging task to rationally design light-driven lignin deconstruction with decent photocatalytic selectivity and durability for developing scalable photobiorefining. A bottom-up approach, beginning with representative model compounds as lignin intermediates, enables a chance to encompass well-defined photocatalytic mechanism/system for providing insights, feasibility, and guidelines before the technical or proto-lignin conversion. The emphasis of this review is mainly placed on photocatalytic lignin-first strategy that includes versatile photocatalyst types, transformation pathways, photoreactors, and reaction medium. The cleavage mechanisms of C–O (e.g., β-O-4′ and α-O-4′) and C–C (e.g., β-1′ and β-5′) linkages in native lignin and its models to form light aromatic hydrocarbons through homogeneous or heterogeneous photocatalysis are proposed. At the end, the remaining challenges for the selective control and practical spread of photocatalytic lignocellulose fractionation are elaborated, and burgeoning prospects to inspire opportunities on photocatalyst manipulation for efficient and sustainable light-mediated lignin conversion are also discussed. The present work sheds light on the structure–property–performance relationship in photocatalytic lignin valorization and forthcoming knacks to spark the bright pearl of high-performance photobiorefining. [ABSTRACT FROM AUTHOR]

Homogenization of heterogeneous catalysts is a valuable and interesting research topic. Porous polypyridine-oxadiazole (PPO), as not only a carrier but also a ligand, was designed and synthesized from pyridine-oxadiazole and 1-iodo-4-vinylbenzene. Iridium was anchored onto the skeleton of this polymer (ligand) through coordination bonds. This porous polypyridine-oxadiazole iridium catalyst (PPO-Ir) was clearly characterized by XRD, BET, EDS, HRTEM, SEM, and XPS, and revealed high catalytic activity for the reaction of dimethyl-6-aminouracil with benzyl alcohols, 1,3-dimethylbarbituric acid with benzyl alcohols and 2-aminobenzylamine and benzyl alcohols through dehydrogenation and the borrowing hydrogen strategy with alcohol or water as the solvent. In addition, this PPO-Ir catalyst could be recycled and reused without a manifest loss of catalytic activity for at least five times and revealed potential application value. The mechanism explorations were further conducted to clarify this PPO-Ir and these transformations. [ABSTRACT FROM AUTHOR]

The photocatalytic reforming of lignin for H2 evolution can simultaneously overcome environmental and energy issues. However, the photocatalytic activity is still far from useful, considering lignin's complex structure. Therefore, this poses a huge challenge for the design of photocatalysts via ingredient/heterojunction regulation synergistic effects. Herein, in situ Mo-doped and metallic Ni-supported ZnIn2S4-wrapped NiMoO4 step-scheme (S-scheme) heterojunctions (NMO@M–ZIS–N) were developed via a reduction strategy assisted by thermal dissolution. The introduction of NMO can significantly inhibit the agglomeration of ZIS and expose more active sites. The close contact of the two phases helps to form a S-scheme heterojunction, which effectively promotes the separation and transport of photogenerated electron–hole pairs. Due to its unique structural design, the optimal hybrid heterojunction can exhibit excellent photocatalytic hydrogen evolution reaction (HER) activity (5.14 mmol h−1 g−1 for TEOA and 0.53 mmol h−1 g−1 for lignin). The superior photocatalytic performance can be mainly attributed to the synergistic effect of S-scheme heterojunctions coupled with Mo doping and metallic Ni supports to broaden the light absorption, enhance the kinetic process of charge transport, and retain strong redox ability, thereby promoting the photocatalytic HER activity. [ABSTRACT FROM AUTHOR]

The quantitation of lignin is essential for the evaluation, conversion, and utilization of lignocellulosic biomass. However, the existing lignin quantitation methods like the widely used Klason method still have some disadvantages, such as requiring hazardous reagents, complicated steps, heating, introducing interfering substances, and low sensitivity. In this study, a novel green method for lignin quantitation based on the completely dissolved solution of lignocellulosic biomass in LiCl/DMSO and UV spectrophotometry (LiCl/DMSO CDS-UV method) was developed. The process does not require complex chemical pretreatment and separation of lignin from lignocellulosic biomass. The biomass samples extracted with benzene/ethanol (v/v 2 : 1) can be completely dissolved in an 8% LiCl/DMSO solvent system at room temperature (25 °C) and atmospheric pressure after short-time ball milling (3 h). For the chemical delignified samples with a low lignin content, the completely dissolved solution can be obtained only by heating the solution to 60 °C and stirring at atmospheric pressure for 2 h. Then the lignin content of the solution was determined by UV spectrophotometry. Different species of biomass including herbage (wheat straw), hardwood (black poplar), softwood (redwood), bark (eucalyptus bark and redwood bark), and above biomass treated by different delignification methods and degrees were applied to establish the LiCl/DMSO CDS-UV method and extend the applicability of this method. The results quantified by the LiCl/DMSO CDS-UV method were compared with the total lignin content measured by the Klason method and a good correlation was observed. The LiCl/DMSO CDS-UV method only requires trace samples (0.1 g) to achieve a precise determination of the lignin content, the conditions are mild, no hazardous reagents are used and no interfering substances are produced in the process. [ABSTRACT FROM AUTHOR]

Remote controllable photothermal elastomers can realize precise non-contact control through the photothermal conversion effect, highlighting a new routine for light energy utilization and a promising direction for smart materials. Developing biomass-based photothermal materials is an important strategy to promote the realization of carbon neutrality and improve the environmental friendliness of photothermal elastomers. In this work, green biomass lignin was demonstrated as an efficient photothermal agent for preparing smart elastomer composites with versatile functionalities, owing to the fact that the conjugated structures in lignin could effectively promote electron transitions from low-energy orbitals to high-energy states and the visible and near-infrared (NIR) light energy absorbed by lignin was mainly released in the form of non-radiative transition. A high photothermal conversion efficiency of 53.7% was obtained for low molecular weight alkaline lignin with the photothermal temperature exceeding 280 °C under NIR irradiation (808 nm, 1.25 W cm−2). Under the stimulation of NIR light, the alkaline lignin/polyethylene elastomer (POE) composite exhibited a good light-triggered shape memory effect, excellent light-controlled self-repairing properties with the self-repairing efficiency as high as 98.2% (808 nm, 1.25 W cm−2, 20 min), and strong photothermal bactericidal activity. Meanwhile, a series of functional applications were demonstrated based on the excellent photothermal effect of lignin, such as photothermal engines, photothermal generators and photothermal switches, which endowed lignin-based elastomer composites with considerable application prospects in smart materials for precise remote driving of robots, machines, sensors, sterilization and self-repairing equipment, etc., promoting the sustainable development and high-value utilization of biomass lignin. [ABSTRACT FROM AUTHOR]

In the past few years, cellulose nanomaterials obtained from lignocellulose have attracted extensive attention as functional nanomaterials with excellent properties and great application potential in a variety of high-tech fields. However, the preparation of cellulose nanomaterials is facing several challenges such as the large amount of energy consumption, chemical recovery issues, and complicated purification and pretreatment processes, which have limited their large-scale application. Fortunately, lignin-containing cellulose nanomaterials have emerged as a new type of cellulose nanomaterial because of the low energy and chemical consumption, easy preparation process, and special properties. This review showcases a comprehensive overview of research status on the preparation and application of lignin-containing cellulose nanomaterials, focusing on recently developed green and low-cost preparation processes. The potential applications of lignin-containing cellulose nanomaterials as building blocks and reinforcing agents for the design of various advanced materials are summarized as well. Finally, the current challenges and future directions for the preparation and application of lignin-containing cellulose nanomaterials are provided. [ABSTRACT FROM AUTHOR]

The conversion of lignocellulose into a value-added chemical with high selectivity is of great significance but is a big challenge due to the structural diversities of biomass components. Here, we have reported an efficient approach for the one-step conversion of raw lignocellulose into diethyl maleate by the polyoxometalate ionic liquid [BSmim]CuPW12O40 in ethanol under mild conditions. The results reveal that all of the fractions in biomass, i.e., cellulose, lignin and hemicellulose, were simultaneously converted into diethyl maleate (DEM), achieving a 329.6 mg g−1 yield and 70.3% selectivity from corn stalk. Importantly, the performance of the ionic liquid catalyst [BSmim]CuPW12O40 was nearly twice that of CuHPW12O40, which can be attributed to the lower incorporation of the Cu2+ site in [BSmim]CuPW12O40. Hence, this process opens a promising route for producing bio-based bulk chemicals from raw lignocellulose without any pretreatment. [ABSTRACT FROM AUTHOR]

Canonical lignification occurs via the coupling of phenolic radicals, in which chain extension can occur only from phenolic ends of growing polymer chains. Radical coupling of catechyl monomers, including caffeyl and 5-hydroxyconiferyl alcohols, gives rise to benzodioxane units in the polymer. Anticipating that a catechol could oxidize to its o-benzoquinone analog under the dehydrogenative (oxidative) conditions of lignification, we examined the possibility that an o-benzoquinone, as the diene component, could also incorporate into lignin via another mechanism, the Diels–Alder cycloaddition reaction. The o-benzoquinone derived from methyl 5-hydroxyvanillate and 4-O-methylconiferyl alcohol served as models for the diene and dienophile, respectively, and produced Diels–Alder products in vitro. Two types of Diels–Alder products were found: (i) when the 1,2-diketone of the quinone acts as the diene in a hetero-Diels–Alder reaction, a benzodioxane structure was produced with a different regiochemistry than the benzodioxane isomer produced via radical coupling; (ii) when the quinone's diene participated in the Diels–Alder reaction, a distinctive oxatricyclo structure was produced. Both features may be used as markers for the occurrence of Diels–Alder reactions in lignification. Examination of natural lignins derived from catechyl monomers, however, did not reveal evidence for such products. The conclusion is that the only significant reactions in lignification are combinatorial radical coupling reactions of the single-electron-oxidized phenolics and that polymer chain extension therefore occurs only from the phenolic end-units even in the special case of plants that utilize catechyl monomers for lignification. [ABSTRACT FROM AUTHOR]

The present report focuses on the solvent effect on furfural production from xylose in biphasic systems with methods including combined experiments, molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Six most effective and commonly used biphasic solvents for furfural production were comparatively analyzed and discussed based on the kinetic study, partition coefficient, degradation behavior of furfural in organic solvents, distribution of solvent molecules around xylose/furfural molecules, hydrogen bonding, moving trajectories of xylose/furfural, and the solvation free energy. During the hydrothermal reaction of xylose to furfural in biphasic systems, it was found that the conversion efficiency of biphasic systems can be ordered as DCM/H2O > 2-MTHF/H2O > 2-butanol/H2O ≈ MIBK/H2O > CPME/H2O > toluene/H2O according to the xylose conversion and furfural yield, which are dominated by the solvation free energy (ΔGsol) of furfural in organic solvents, and also be affected by three other factors, namely, the maximum solubility of furfural in organic solvents, the ΔGsol value of organic solvents in water, and the side reaction of furfural in organic solvents. The degradation rate of furfural in 2-butanol was detected to be the fastest, and molecular dynamics simulation data showed that the hydrogen bonding between furfural and 2-butanol may accelerate the degradation of furfural. DCM has excellent extraction ability for furfural, and the maximum furfural yield in the DCM/H2O system (81.64%) is much higher than that in other systems during the hydrothermal reaction without additional catalysts. [ABSTRACT FROM AUTHOR]

Cellulose-based films have attracted significant attention in the fields of flexible photoelectric products and energy equipment by virtue of their abundant sources, biodegradability, renewability, sustainability, and optical properties, of which high transmittance and high haze are important parameters. In this study, we proposed a green and efficient defibrillation and carboxylation method of KMnO4 synergized with slight homogenization to produce fine carboxylated cellulose nanofibrils (COOH-CNFs) with a high yield of 96%. The oxidation reaction was carried out under mild conditions (50 °C, 2 h). The as-prepared COOH-CNFs well-retained the crystalline structure of the pulp with coexisting crystalline and amorphous regions. This structure gave the COOH-CNF film unique optical properties, including a transmittance above 80% at a wavelength of 550 nm, a haze reaching 97.45%, and no obvious absorption in the ultraviolet-visible range. The resulting COOH-CNFs were characterized in terms of fibrillation yield, morphological features, crystal structure, surface chemistry, and mechanical behavior. This CNF preparation approach is advantageous over traditional methods owing to a reduced reactant dosage and enhanced efficiency, which represents a potential green route in industry and makes it a promising candidate for fabricating films for flexible lighting, energy, and sensing devices. [ABSTRACT FROM AUTHOR]

The selective oxidation of monosaccharides into sugar acids is an important reaction for the production of biomass-based chemicals, but the design of an efficient catalyst remains a big challenge. Herein we report a series of efficient and stable surface functionalized carbon nanotube supported palladium catalysts for the selective oxidation of monosaccharides into sugar acids at room temperature. The palladium nanoparticles supported on alkaline carbon nanotubes (Pd/CNT-N) showed the highest reaction activity. The maximum gluconic acid yield of 98.3% and xylonic acid yield of 95.8% were obtained at 30 °C within 180 min. DFT calculations revealed that the mechanism of xylose oxidation to xylonic acid involved the activation of OH−, adsorption of xylose, dissociation of the formyl C–H bond in xylose, formation of chemisorbed xylonic acid, and desorption of xylonic acid. The activation energy barrier for xylose oxidation over Pd/CNT-N is lower than that of Pd/CNT-O, explaining that the basic groups on CNT are more beneficial for accelerating monosaccharide oxidation and enhancing the sugar acid selectivity. This work not only presents a new facile route to produce sugar acid at room temperature, but also provides a basis to design and develop efficient catalysts with surface functionalized supports for various catalytic reactions. [ABSTRACT FROM AUTHOR]

Formic acid (HCO2H) is widely used in various chemical processes, applied in fuel cells, and considered as a promising candidate for hydrogen storage. Currently, industrial production of HCO2H mainly depends on fossil resources using multiple processes. Practical HCO2H production from renewable resources for the potential industrial application is rare. Herein, we demonstrate practical dimethyl sulfoxide (DMSO) (1 v%)-promoted selective hydrolysis–oxidation of lignocellulosic biomass to HCO2H, which is demonstrated by recycling experiments of near 10 gram-scale wheat straw with constantly high efficiencies. Mechanism studies on the major unit of lignocellulosic biomass, glucose, disclose that the high selectivity and yield of HCO2H are attributed to the hydrogen bonds of DMSO with generated gem-diol groups from the reaction of glucose, or the intermediates of glycolaldehyde and glyoxal with water (H2O). The formation of hydrogen bonds is indicated both by DFT calculations and IR experiments. [ABSTRACT FROM AUTHOR]

Integrating multifarious capabilities within a waste-free biorefinery has been the cornerstone to ignite scalable design of holistic biomass valorization. Fostering the versatile utilization of industrial effluents and residual lignin from traditional biorefineries has become an imminent issue to be tackled. A green and tandem approach was proposed to simultaneously produce carbon dots (CDs), fermentable sugar, and lignin-installed lithium–sulfur (Li–S) cells from eucalyptus with the aid of L -cysteine-catalyzed hydrothermal pretreatment. The total yield of xylooligosaccharides (XOS) reached up to 50.16% (w/w) of xylan that was directly extracted from the wood skeleton by a moderate acidic hydrothermal environment, including 22.03% of XOS with a low degree of polymerization (DP 2–6). The graphite N, S-doped CDs with a bright blue fluorescence, which mainly originated from the irregular conjugation of xylan, lignin and L -cysteine, had an average diameter at 4.7 nm confined to a quasi-spherical shape. The proper alleviation of amorphous ingredients and recalcitrant intercellular structure can be attributed to autohydrolysis with the assistance of an amino acid, thereby fostering the enzymatic digestibility of well-preserved cellulose from 15.1% to 82.4%. From cellulose enzymatic lignin (CEL) capable of high abundance of β-aryl ether and hydroxyl groups, a hierarchically structured heteroatom-doped biochar with exposed active sites (N, S, O-induced intrinsic defects and surface states) was synthesized via using a dual-template. It can serve as an available candidate for the molten sulfur host to install a Li–S cathode that retained 582 mA h g−1 at 1C after 300 cycles with the average coulombic efficiency and capacity decay per cycle being 93.79% and 0.098% respectively. With the advent of bioethanol techniques, the all-round pathway brings a graceful prelude for boosting the revenue of waste-free biorefineries that has inspired application-worthy products from biomass waste streams, including photoluminescent CDs and rechargeable Li–S cells. [ABSTRACT FROM AUTHOR]

Although measuring lignin contents is a routine operation for biomass compositional analysis in process development aiming at efficient utilization of woody biomass, it is still a challenging task requiring many steps, hazardous reagents, heating, and a significant time. A facile spectroscopic method, our CASA (Cysteine–Assisted Sulfuric Acid) method, was developed to quantify the lignin content of lignocellulosic biomass, based on an extraordinary system in which biomass samples are fully dissolved in 72% H2SO4 containing cysteine at 24 °C in 60 min. Using synthetic lignins, the lignin absorptivities were determined to be 17.25 g−1 L cm−1 for softwood lignin and 11.23 g−1 L cm−1 for hardwood lignin and monocot lignin. Seven softwoods, six hardwoods, and six monocots were tested using the CASA method. A high coefficient of determination (R2 = 0.95) was found between the CASA results and the acid-insoluble lignin contents, and an even better R2 (0.98) was obtained when the CASA data were correlated with the total lignin contents. [ABSTRACT FROM AUTHOR]

Correction for 'Mo-Doped/Ni-supported ZnIn2S4-wrapped NiMoO4 S-scheme heterojunction photocatalytic reforming of lignin into hydrogen' by Hang Su et al., Green Chem., 2022, DOI: 10.1039/d1gc04397h. [ABSTRACT FROM AUTHOR]