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The previous research addressed the waste problem of agriculture and forestry residues by exploring the efficient utilization of liquefied soybean straw in supercapacitor. The structures of the liquefied soybean straw were controlled by coupling microwave hydrothermal treatment with carbonization under the influence of a C3N4 bifunctional template. What's more, C3N4 could effectively regulate the pore structures and provide an effective N active site of carbon materials C3N4. The obtained N-SLR Carbon-700 possess a specific surface area of up to 1593.7 m2 g-1, and the pore size is mainly concentrated in the range of 1.8-2.5 nm, providing efficient ions transmission channels and storage space. Its specific capacitance is up to 261.5F g-1 (current density of 0.5A g-1), and the capacity retention is 74.04% when the current density is expanded by 20 times. In the two-electrode system, the energy density of N-SLR Carbon-700 could reach to 31.3 W h kg-1 at a power density of 360 W kg-1, as well as the energy surface density is maintained at 69% when the power density is increased by a factor of 20. This work enhances effectively the charging and discharging stability and capacitance value of carbon-based supercapacitor., (© 2024 Wiley‐VCH GmbH.)

The development of greener and more sustainable synthesis processes for manufacturing commodity chemicals is of great importance. The majority of current phenol production methods involve harsh reaction conditions with high energy consumption, causing severe environmental pollution. In this study, we present a novel approach for the decarboxylation of hydroxybenzoic acids (HBAs) to phenol using a choline chloride-urea (ChCl-urea) deep eutectic solvent (DES). Our study reveals the remarkable dual performance of ChCl-urea both as a catalyst and solvent for the decarboxylation of HBA, resulting in a high phenol yield (94 mol%) under mild reaction conditions. The proposed reaction pathway, established through a combination of experiments and computational simulations, enhances our understanding of this process. The recyclability of the DES system during decarboxylation was also assessed. Our findings demonstrate that the integration of DES into conventional chemical processes can pave the way for sustainable manufacturing, exemplifying a novel approach for producing phenol from abundant natural resources using designer solvents., (© 2024 Wiley‐VCH GmbH.)

Enzymatic polymerization of lignosulfonate (LS) has a high potential for various applications ranging from coatings to adhesives. Here, the effect of different ions in low concentrations on enzymatic polymerization of LS was investigated, including salt solutions consisting of mono- and dicarboxylic acids, sulfate, phosphate and chloride with sodium as counter ion. LS polymerization was followed by viscometry and size exclusion (SEC) chromatography. Interestingly, there was only a small effect of ions on the activity of the laccase on standard substrate ABTS, while the effect on polymerization of LS was substantially different. The presence of acetate led to a 39 % higher degree of polymerization (DP) for LS. Small angle X-ray scattering (SAXS) revealed that the structure of the enzyme was largely unaffected by the ions, while the determination of the zeta potential showed that those ions conveying higher negative surface charges onto LS particles showed lower DPs, than those not affecting the surface charge. Further, electron paramagnetic resonance (EPR) spectroscopy showed 5-times higher intensity in phenoxyl radicals for the monovalent ions compared to the divalent ones. It was concluded that the DPs of LS could be tuned in the presence of certain ions, by facilitating the interaction between the laccase substrate-binding site and the LS molecules., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Interface modification and bulk doping are two major strategies to improve the photovoltaic performance of perovskite solar cells (PSCs). Dipolar molecules are highly favored due to their unique dipolarity. This review discusses the basic concepts and characteristics of dipoles. In addition, the role of dipoles in PSCs and the corresponding conventional characterization methods for dipoles are introduced. Then, we systematically summarize the latest progress in achieving efficient and stable PSCs in dipole materials at several key interfaces. Finally, we look forward to the future application directions of dipole molecules in PSCs, aiming at providing deep insight and inspiration for developing efficient and stable PSCs., (© 2024 Wiley-VCH GmbH.)

Perovskite solar cells (PSCs) are usually modified and passivated to improve their performance and stability. The interface modification and bulk doping are the two basic strategies. Fluorine (F)-containing materials are highly favored because of their unique hydrophobicity and coordination ability. This review discusses the basic characteristics of F, and the basic principles of improving the photovoltaic performance and stability of PSC devices using F-containing materials. We systematically summarized the latest progress in the application of F-containing materials to achieve efficient and stable PSCs on several key interface layers. It is believed that this work will afford significant understanding and inspirations toward the future application directions of F-containing materials in PSCs, and provide profound insights for the development of efficient and stable PSCs., (© 2024 Wiley-VCH GmbH.)

Current DES pretreatment is often performed under relatively severe conditions with high temperature, long time, and high DES usage. This work studied a short-time diol DES (deep eutectic solvent) pretreatment under mild conditions to fractionate the bamboo, facilitate enzymatic hydrolysis, and obtain high-quality lignin. At an optimized condition of 130 °C for only 10 min, lignin and xylan removal reached 61.34 % and 84.15 %, with residual glucan showing a ~90 % enzymatic hydrolysis yield. Equally important, the dissolved lignin could be readily recovered with 97.51 % yield, exhibiting 96.65 % β-O-4 preservation. The fractionation and lignin protection mechanisms were unveiled by XRD, FTIR, cellulose-DP, 2D HSQC NMR, 31 P NMR and GPC analysis. This study highlighted that short-time fractionation of bamboo can be achieved by a diol-based DES which is an ideal strategy to upgrade the lignocellulose biomass for high enzymatic hydrolysis yields and high-quality lignin stream., (© 2023 Wiley-VCH GmbH.)

Different forms of HCOOH in the depolymerization system play an important role in governing the monomeric products from lignin. We reported two strategies for the introduction of HCOOH to enrich the monophenols from kraft lignin by microwave-assisted depolymerization. The reaction of lignin models showed that HCOOH was in favor of the cleavage of C-O bonds (β-O-4 typically) and partial C-C bonds (C α -C β ). Subsequently, Microwave-assisted depolymerization of lignin with two strategies was conducted via a designed dynamic vapor flow reaction system. Strategy A with HCOOH as pretreatment solvent showed excellent monophenols enrichment with total mass yields of 193.71 mg/g (lignin basis). Strategy B using HCOOH as reforming solvent vapor significantly increased the monophenols selectivity. It presented unique reforming and upgrading performance by generating catechol (42.59 mg/g, lignin basis) and homovanillic acid (17.58 mg/g, lignin basis). This study provided potential strategies for the efficient conversion of kraft lignin into high-value platform chemicals., (© 2024 Wiley-VCH GmbH.)

Current techniques of lignin conversion are challenged by the low carbon utilization efficiency resulting from the severe generation of residual solid (char). Therefore, a better understanding of pathway for char formation is significant and highly desired for lignin valorization. In this work, we propose a fundamental mechanistic insight into char formation in lignin depolymerization, using hydrothermal decomposition as model reaction. The results demonstrate that the char featuring a multi-layer construction of coke and oligomer contains mainly G units, primarily generated from native G-lignin and demethoxylation of S-lignin. Instead, H-lignin contributes to the formation of volatile monophenols. Furthermore, new methylene bridges form between the benzene rings in lignin, which consequently results in the formation of recalcitrant char. Based on these observations, a plausible mechanism for char formation is proposed and verified by the density functional theory calculation., (© 2023 Wiley-VCH GmbH.)

Traditionally, phenols used to prepare phenol-formaldehyde (PF) resin adhesives are obtained from phenolic compounds and various chemicals, which are extracted from petroleum-based raw materials. Lignin, a sustainable phenolic macromolecule in the cell wall of biomass with an aromatic ring and a phenolic hydroxyl group similar to those of phenol, can be an ideal substitute for phenol in PF resin adhesives. However, only a few lignin-based adhesives are produced on a large scale in industry, mainly because of the low activity of lignin. Preparing lignin-based PF resin adhesives with exceptional achievements by modifying lignin instead of phenol is an efficient method to improve the economic benefits and protect the environment. In this review, the latest progress in the preparation of PF resin adhesives via lignin modification, including chemical, physical, and biological modifications, is discussed. In addition, the advantages and disadvantages of different lignin modification methods for adhesives are compared and discussed, and future research directions for the synthesis of lignin-based PF resin adhesives are proposed., (© 2023 Wiley-VCH Verlag GmbH.)

Heterogeneously catalyzed depolymerization of lignin to value-added chemicals is increasingly attractive but highly challengeable. Particularly, the diffusion limitation of lignin macromolecule to the solid catalyst surface is a big barrier, which significantly decreases the yield of monomer while increasing char formation. Therefore, for the potential industrial utilization of lignin, new knowledge focused on the size of lignin particles is of great importance to offer guidance for promoting lignin depolymerization and suppressing condensation in the heterogeneously catalytic systems. In this Review, the size of lignin particles and macromolecules are summarized. Previous approaches for improving the mass diffusion including enhancing the solubility of lignin and exploitation of hierarchical and "solubilized" materials are also discussed. Based on these, a constructive perspective is proposed. Thus, this work provides a new insight on the rational design of heterogeneous catalytic techniques for efficient utilization of the aromatic polymer of lignin., (© 2023 Wiley-VCH GmbH.)

Providing sustainable energy storage is a challenge that must be overcome to replace fossil-based fuels. Redox flow batteries are a promising storage option that can compensate for fluctuations in energy generation from renewable energy production, as their main asset is their design flexibility in terms of storage capacity. Current commercial options for flow batteries are mostly limited to inorganic materials such as vanadium, zinc, and bromine. As environmental aspects are one of the main drivers for developing flow batteries, assessing their environmental performance is crucial. However, this topic is still underexplored, as researchers have mostly focused on single systems with defined use cases and system boundaries, making the assessments of the overall technology inaccurate. This review was conducted to summarize the main findings of life cycle assessment studies on flow batteries with respect to environmental hotspots and their performance as compared to that of other battery systems., (© 2023 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Due to the poor enzyme thermal stability, the efficient conversion of high crystallinity cellulose into glucose in aqueous phase over 50 °C is challenging. Herein, an enzyme-induced MOFs encapsulation of β-glucosidase (β-G) strategy was proposed for the first time. By using various methods, including SEM, XRD, XPS, NMR, FTIR and BET, the successful preparation of a porous channel-type flower-like enzyme complex (β-G@MOFs) was confirmed. The prepared enzyme complex (β-G@MOFs) materials showed improved thermal stability (from 50 °C to 100 °C in the aqueous phase) and excellent resistance to ionic liquids (the reaction temperature was as high as 110 °C) compared to the free enzyme (β-G). Not only the catalytic hydrolysis of cellulose by single enzyme (β-G) in ionic liquid was realized, but also the high-temperature continuous reaction performance of the enzyme was significantly improved. Benefiting from the significantly improved heat resistance, the β-G@MOFs exhibited 32.1 times and 34.2 times higher enzymatic hydrolysis rate compared to β-G for cellobiose and cellulose substrates, respectively. Besides, the catalytic activity of β-G@MOFs was retained up to 86 % after five cycles at 110 °C. This was remarkable because the fixation of the enzyme by the MOFs ensured that the folded structure of the enzyme would not expand at high temperatures, allowing the native conformation of the encapsulated protein well-maintained. Furthermore, we believe that this structural stability was caused by the confinement of flower-like porous MOFs., (© 2022 Wiley-VCH GmbH.)

Pyrolysis is one of the most widely utilized protocols for the preparation of nanoconfined metal species for heterogeneous catalysis, but it still suffers from the uncontrollable composition evolution process with undesired metal sintering and porous structure collapse. Herein, a novel and versatile molten salt-assisted pyrolysis strategy was demonstrated for the preparation of ultrasmall transition-metal nanoparticles embedded in hollow hierarchical carbon skeletons. The preparation only involved the fabrication of metal-organic framework templates and subsequent pyrolysis with the addition of KCl-KBr molten salt, which played a crucial role in pore size extending and metal sintering inhibiting. Benefitting from the encapsulation effect, the as-synthesized Cu@HHC materials exhibited remarkable catalytic performance and recycling stability in the selective oxidation of biomass-derived 5-hydroxymethylfurfural into 2,5-diformylfuran under mild reaction conditions., (© 2022 Wiley-VCH GmbH.)

5-hydroxymethylfurfural (HMF) is considered to be one of the most pivotal multifunctional biomass platform chemicals. This Review discusses recent advances in catalytic oxidation of HMF towards high-value products. The reaction mechanism of different noble metals and the path of HMF oxidation to high-value products have been deeply investigated in the noble metal catalytic system. The reaction mechanisms of different noble metals and HMF conversion paths were compared in detail. Moreover, the factors affecting the performance of different noble metal catalysts were summarized. Finally, effective strategies were put forward to improve the catalytic performance of noble metal catalysts. The purpose is to provide a valuable reference for the academic research on the preparation of oxidation products from biomass-based HMF and the industrial application of noble metal catalysts., (© 2022 Wiley-VCH GmbH.)

As a new and green type of nanomaterials, lignin nanoparticles (LNPs) have been considered as high-value renewable materials for application in many fields. However, the industrialization of LNPs faces many challenges, such as high manufacturing costs and small-scale production. Here, a simple but rapid and reversible approach for the fabrication of LNPs was provided via switching pH environments. The LNPs were regularly shaped in the acetonitrile/water system, and their size appeared to be very homogeneous. The alternation of forming and dissolving of LNPs could be repeated many times simply by alternately adding acid and alkaline solutions. There was little difference in the molecular structures between the original and regenerated LNPs. In addition, the consumption of solvents for LNPs production was only 200 mL g -1 , reduced by more than 10 times compared with conventional solvent exchange methods. The concentration of LNPs in the solution also improved to 5.0 g L -1 . This study not only provides a new, simple, and effective strategy for the fabrication of LNPs but also paves the way towards their real green production and application., (© 2022 Wiley-VCH GmbH.)

The catalytic hydrodeoxygenation (HDO) of lignin has long been a hot research topic and vacancy engineering is a new means to develop more efficient catalysts for this process. Oxygen vacancies and sulfur vacancies are both widely used in HDO. Based on the current research status of vacancies in the field of lignin-derived oxygenates, this Minireview discusses in detail design methods for vacancy engineering, including surface activation, synergistic modification, and morphology control. Moreover, it is clarified that in the HDO reaction, vacancies can act as acidic sites, promote substrate adsorption, and regulate product distribution, whereas for the catalysts, vacancies can enhance stability and reducibility, improve metal dispersion, and improve redox capacity. Finally, the characterization of vacancies is summarized and strategies are proposed to address the current deficiencies in this field., (© 2021 Wiley-VCH GmbH.)

Pretreatment with efficient fractionation, eco-friendliness, and low-cost brings high security to future biorefinery systems. Synergistic pretreatment is a compelling blueprint to tackle the compact structure of lignocellulose towards a high-level valorization. Here, a stepwise approach was designed using hydrothermal and deep eutectic solvent (DES) pretreatments to hierarchically extract hemicelluloses and lignin from poplar, while delivering a cellulose-rich substrate that could easily undergo enzymatic hydrolysis to obtain fermentable glucose and residual lignin. The lifetime of recyclable DES showed that the pretreatment efficiency was still largely maintained after the fourth recycling. An enhancement of enzymatic digestibility from 13.9 to 90.4 % was initiated by the deconstruction of amorphous portions and robust cell wall. 23.7 % Xylooligosaccharides (degree of polymerization 2-6), 47.5 % DES-isolated lignin, and 19.2 % cellulose enzymatic lignin were harvested via this coupled process. This study could promote the precise design of sustainable tandem pretreatment that can boost the frontier of highly available biorefinery., (© 2021 Wiley-VCH GmbH.)

In the past five years, biomass-derived biofuels and biochemicals were widely studied both in academia and industry as promising alternatives to petroleum. In this Review, the latest progress of the synthesis and fabrication of porous nanocatalysts that are used in catalytic transformations involving hydrogenolysis of lignin is reviewed in terms of their textural properties, catalytic activities, and stabilities. A particular emphasis is made with regard to the catalyst design for the hydrogenolysis of lignin and/or lignin model compounds. Furthermore, the effects of different supports on the lignin hydrogenolysis/hydrogenation are discussed in detail. Finally, the challenges and future opportunities of lignin hydrogenolysis over nanomaterial-supported catalysts are also presented., (© 2021 Wiley-VCH GmbH.)

γ-Valerolactone (GVL), derived from renewable lignocellulosic biomass, has been considered as a cost-competitive and green platform chemical. With the increasingly prominent environmental problems, a deep understanding of the preparation and transformation of GVL is highly needed. Based on the latest progress made with GVL, preparation and applications of GVL are summarized and discussed in this Review. In particular, the state-of-the-art in catalytic production of GVL is described based on the use of noble-metal and non-noble-metal catalysts. The application of GVL for the valorization of lignocellulose would improve the yield of target products such as sugar monomers and furfural. Thus, GVL can be produced from lignocellulose and simultaneously it can also be used for the valorization of lignocellulose, just as in the sustainable and renewable cycle, "the falling leaves returns to their roots". This Review is expected to provide valuable reference and new proposal for the further development and better utilization of GVL., (© 2020 Wiley-VCH GmbH.)

Copper(II) oxide featuring a narrow bandgap and low toxicity has been frequently applied in the visible-light-driven photocatalytic hydrogen evolution, but it suffers from large intrinsic overpotential and low water adsorption capacity. Herein, we report a self-templated strategy for the preparation of carbon-doped CuO hollow spheres (C-CuO HSs) through thermal transformation of a hierarchical MOF. The hierarchical Cu-MOFs not only act as a template to form interior voids during the thermal transformation, but also serve as precursors to dope C atoms into the CuO lattice. The as-synthesized C-CuO HSs exhibits remarkable photocatalytic performance with a H 2 evolution rate of 67.3 mmol/g/h and the apparent quantum efficiency of 25.3 % at 520 nm in the present of eosin-Y photosensitizer. The high performance of C-CuO HSs is attributed to the hierarchical porous structure and modulated electronic structure of CuO by C-doping with well exposed reactive sites, high water adsorption capability, and low water reduction reaction barrier. The results presented in this work might shed light on the design of high-performance photocatalysts for various energy-related applications., (© 2020 Wiley-VCH GmbH.)

Phenolation is a commonly used method to improve the reactivity of lignin for various applications. In this study, resinol lignin models (syringaresinol and pinoresinol) and eucalyptus alkali lignin were treated under acid-catalyzed phenolation conditions to investigate the products derived from resinol (β-β) structures of lignins. The phenolation products were characterized by means of GC-MS and NMR spectroscopy following separation using flash chromatography and thin-layer chromatography. A series of new naphthalene products were identified from phenolation of syringaresinol, and the corresponding guaiacyl analogs were also identified by GC-MS. The C1-Cα bond of these resinol compounds was cleaved to release syringol or guaiacol during phenolation. In addition, diphenylmethane products formed from phenol or phenol and syringol/guaiacol were found in the phenolation products. Comparatively, more naphthalene products were obtained by phenolation from syringaresinol than those obtained from pinoresinol. HSQC NMR characterization of the phenolated alkali lignin revealed that naphthalene structures formed in the phenolated lignin., (© 2020 Wiley-VCH GmbH.)

The hydrogenation of furfural (FUR), a typical bio-based furan derivative, is a critical reaction within the roadmap for upgrading lignocellulosic biomass into high value-added chemicals and liquid fuels, the performance of which is strongly correlated with the catalysts' intrinsic peculiarities. Metal catalysts with tailorable sizes, uniform dispersions and robust sintering resistance are generally recognized as a prerequisite for obtaining better hydrogenation activity, selectivity and stability, which has prompted intensive research into metal particle size effects and their regulation strategies. The roles of metal particle sizes and corresponding dispersions of metal catalysts used for FUR hydrogenation have been clearly recognized to be crucial over the past decade. In this regard, this systematic Minireview aims to provide profound insights into particle size effects in the metal-catalyzed hydrogenation of FUR, as well as conditional and structural approaches to regulating these effects. In addition, from the aspect of catalyst stability, the impacts and improvements of the metal particle sintering issue are analyzed. Moreover, several suggestions are proposed in response to the challenges in regulating particle size effects. Furthermore, the viewpoints presented herein would potentially contribute to the rational development of metal hydrogenation catalysts and further help to boost a more sustainable biomass refining system., (© 2020 Wiley-VCH GmbH.)

The valorization of lignin to replace phenol is significant in the production of phenolic resins. However, a great challenge is to produce lignin-based resin (LR) with a suitable viscosity and high substitution rate of lignin to phenol. In this study, LRs were produced using hardwood technical lignin derived from the pulping industry. Structural analysis of the LRs indicated that the unsubstituted para and ortho carbon atoms of the aromatic ring influenced the curing temperature and activation energy of the resins. The curing kinetics and thermal decomposition study implied that urea and methylene groups in cured LRs were significant factors that affected the thermal stability negatively. The prepared LRs showed desirable features if used as adhesives to make plywood. This is the first approach in which a substitution rate of up to 65 % is achieved for low-reactive-site hardwood lignin, which provides a solution to the challenge of the simultaneous realization of the high addition of lignin and the adaptive viscosity of resins., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lignin, as the most abundant aromatic biopolymer in nature, has attracted great attention due to the complexity and richness of its functional groups for value-added applications. The yield of production of lignin and the reactivity of prepared lignin are very important to guarantee the study and development of lignin-based chemicals and materials. Various fractionation techniques have been developed to obtain high yield and relatively high-purity lignin as well as carbohydrates (hemicelluloses and celluloses) and to reduce the condensed and degraded nature of conventional biorefinery lignin. Herein, novel and efficient biomass fractionation and lignin fractionation towards lignin valorization are summarized and discussed., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lignins were fractionated in a segmented continuous flow fractionation (SCFF) approach using isocratic or gradient elution profiles of different solvent systems at various flow rates and temperatures against adjustable pressure regimes. Superior control of parameters such as temperature and pressure in combination with the possibility of freely combinable solvent gradients allowed facile fractionation and generation of industrially interesting fractions differing in molecular weight properties and/or in physicochemical properties in a process that could be fully remotely controlled for automation and performance. Scale-up of the process was possible in linear and parallel mode. Analyses of the realised fractions by standardised gel permeation chromatography and 31 P NMR spectroscopy protocols showed that the SCFF of lignins delivered fractions that could be similar to conventional batch fractions, as well as novel/altered fractions available by applying overheated solvents in pressurised systems., (© 2020 Wiley-VCH GmbH.)

Lignin, as the most abundant aromatic renewable biopolymer in nature, has long been regarded as waste and simply discarded from the pulp and paper industry. In recent years, with many breakthroughs in lignin chemistry, pretreatment, and processing techniques, a lot of the inherent bioactivities of lignin, including antioxidant activities, antimicrobial activities, biocompatibilities, optical properties, and metal-ion chelating and redox activities, have been discovered and this has opened a new field not only for lignin-based materials but also for biomaterials. In this Review, the biological activities of lignin and drug/gene delivery and bioimaging applications of various types of lignin-based material are summarized. In addition, the challenges and limitations of lignin-based materials encountered during the development of biomedical applications are also discussed., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lignin-based nanomaterials fabricated by solution self-assembly in organic-aqueous solvent mixtures are among the most attractive biomass-derived products. To accurately control the structure, size, and properties of lignin-based nanomaterials, it is important to achieve fundamental understanding of its dissolution and aggregation mechanisms. In this work, atomic force microscopy (AFM) and molecular dynamics (MD) simulations are employed to explore the dissolution and aggregation behavior of enzymatic hydrolysis lignin (EHL) in different organic-aqueous solvent mixtures at molecular scale. EHL was found to dissolve well in appropriate organic-aqueous solvent mixtures, such as acetone-water mixture with a volume ratio of 7:3, whereas it aggregated in pure water, ethanol, acetone, and tetrahydrofuran. The interactions between the EHL-coated AFM probe and the substrate were 1.21±0.18 and 0.75±0.35 mN m -1 in water and acetone, respectively. In comparison, the interaction decreased to 0.15±0.08 mN m -1 in acetone-water mixture (7:3 v/v). MD simulations further indicate that the hydrophobic skeleton and hydrophilic groups of lignin could be solvated by acetone and water molecules, respectively, which significantly promoted its dissolution. Conversely, only the hydrophobic skeleton or the hydrophilic groups were solvated in organic solvent or water, respectively, inducing serious aggregation of lignin., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lignin is the largest source of renewable aromatic compounds, making the recovery of aromatic compounds from this material a significant scientific goal. Recently, many studies have reported on lignin depolymerization and upgrading strategies. Electrochemical approaches are considered to be low cost, reagent free, and environmentally friendly, and can be carried out under mild reaction conditions. In this Review, different electrochemical lignin conversion strategies, including electrooxidation, electroreduction, hybrid electro-oxidation and reduction, and combinations of electrochemical and other processes (e. g., biological, solar) for lignin depolymerization and upgrading are discussed in detail. In addition to lignin conversion, electrochemical lignin fractionation from biomass and black liquor is also briefly discussed. Finally, the outlook and challenges for electrochemical lignin conversion are presented., (© 2020 Wiley‐VCH GmbH.)

Lignin depolymerization into aromatic monomers with high yields and selectivity is essential for the economic feasibility of biorefinery. However, the relationship between lignin structure and its reactivity for upgradeability is still poorly understood, in large part owing to the difficulty in quantitative characterization of lignin structural properties. To overcome these shortcomings, advanced NMR technologies [2D HSQC (heteronuclear single quantum coherence) and 31 P] were used to accurately quantify lignin functionalities. Diverse lignin samples prepared from Eucalyptus grandis with varying β-O-4 linkages were subjected to Pd/C-catalyzed hydrogenolysis for efficient C-O bond cleavage to achieve theoretical monomer yields. Strong correlations were observed between the yield of monomeric aromatic compounds and the structural features of lignin, including the contents of β-O-4 linkages and phenolic hydroxyl groups. Notably, a combined yield of up to 44.1 wt % was obtained from β-aryl ether rich in native lignin, whereas much lower yields were obtained from technical lignins low in β-aryl ether content. This work quantitatively demonstrates that the lignin reactivity for acquiring aromatic monomer yields varies depending on the lignin fractionation processes., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Non-noble metal-based bifunctional electrocatalysts are highly desired for water electrolysis. However, constructing a water electrolyzer using a sole catalyst without compromising either its oxygen evolution reaction (OER) or hydrogen evolution reaction (HER) performance is still challenging. In this study, a simple strategy is developed to integrate 2 D and 0 D CoP in the same metal-organic framework precursor-derived hollow N-doped carbon nanotube-assembled polyhedron (HNCNP). The unique hierarchical structure endows the resulting nanocomposite with both the advantages of more exposed active sites for 2 D and large surface-to-volume ratio for 0 D materials, whereas the hollow interior could benefit the charge and mass transfer properties. Thus, CoP/HNCNP@2 D CoP exhibits outstanding OER and HER activity and a low cell voltage when employed as both the anode and cathode in a two-electrode water electrolyzer. The approach of integrating the same metal phosphide phase with diverse dimensions may inspire new ways to design hierarchical nanostructures for advanced energy conversion applications., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

As one of the most promising biomass-based platform molecules, γ-valerolactone (GVL) can be synthesized from a variety of lignocellulosic feedstocks through different hydrogen supply pathways. Among these transformation routes, the hydrogenation of levulinic acid (LA) to GVL by using formic acid (FA) as the internal hydrogen source is regarded as a critical path for the sustainable development of renewable energy systems. Although a large number of studies on the synthesis of GVL have been reported, the FA/LA catalytic system has not been interpreted as thoroughly as it should be. In this Minireview, core concerns are focused on key issues and their effects in this FA/LA catalytic system. The catalytic mechanism, together with competitive adsorption behavior between FA and LA on heterogeneous catalysts, is presented. The effects of active metal species and catalyst supports on the overall catalytic performance are summarized, and the influences of key condition parameters, including the time, temperature, FA/LA molar ratios, and aqueous solvent, are discussed. In particular, impacts and improvements of coke deposition and metal leaching, which could greatly affect the catalyst stability, are analyzed in detail. Additionally, several feasible suggestions for the enhancement of the catalytic efficiency and stability are also proposed., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The solid-solid (immobilized cellulase-insoluble cellulose) phase cellulose hydrolysis reaction is significant in cellulosic biomass conversion processes but hindered because of its low efficiency. Herein, a smart temperature-pH dual-responsive material (D-N-N material) was prepared to be used as a carrier for cellulase recovery. This D-N-N material could undergo reversible and switchable transitions between solution, hydrogel, and solid phases. The following results were demonstrated: 1) the hydrolytic degree of this strategy could be as high as that of free cellulase in buffer solution; 2) the cellulase could be encapsulated into the D-N-N hydrogel without significant leaching and most of the cellulase activity was retained after recycling for at least 10 batches; and 3) more than 95 % of the glucose inside the hydrogel could be extracted during the hydrogel-solid transition within 1 h, which can assist in the high-efficiency separation of cellulase from glucose. The results suggested that this strategy provides a feasible platform for efficient cellulose hydrolysis and could be applied to other bio-derived reactions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

With the increase in lignin availability, materials derived from micro- and nano-scale lignin developed rapidly. However, the tedious processes of raw-lignin pretreatment and poor stability seriously restrict the large-scale applications of lignin nanoparticles. To overcome these problems, in this work, a novel green and simple approach was developed to produce super long-term stable lignin nanoparticles (LTSL NPs). The LTSL NPs were prepared directly from black liquor via an acid precipitation method. The obtained LTSL NPs exhibited well uniformity, excellent dispersibility, controllable size, and super long-term stability in aqueous media (no apparent size increase or any particle precipitation for 90 days in neutral water medium). Analyses of nuclear magnetic resonance and ion chromatography revealed that LTSL NPs exhibited higher S/G ratio and higher content of hemicellulose comparing with the lignin nanoparticles which obtained from traditional solvent exchange (ethanol/H 2 O) method. In addition, the size of the LTSL NPs can be well controlled by tuning the degree of acid precipitation (the final pH value). This work not only can promote the development of lignin-based nanomaterials, but also provides a promising utilization pathway for black liquor that simultaneously achieves the fabrication of lignin materials and hemicellulose application., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Invited for this month's cover is the group of Lin Dai and Zhong Liu at TUST and Yonghao Ni at UNB. The image shows how the hemicellulose can play a role in prolonging the stability of lignin nanoparticles The Full Paper itself is available at 10.1002/cssc.201902287., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The efficient hydrodeoxygenation (HDO) of lignin-derived oxygenates is essential but challenging owing to the inherent complexity of feedstock and the lack of effective catalytic approaches. A catalytic strategy has been developed that separates C-O hydrogenolysis and aromatic hydrogenation on different active catalysts with interoperation that can achieve high oxygen removal in lignin-derived oxygenates. The flexible use of tungsten carbide for C-O bond cleavage and a nickel catalyst with controlled particle size for arene hydrogenation enables the tunable production of cyclohexane and cyclohexanol with almost full conversion of guaiacol. Such integration of dual catalysts in close proximity enables superior HDO of bio-oils into liquid alkanes with high mass and carbon yields of 27.9 and 45.0 wt %, respectively. This finding provides a new effective strategy for practical applications., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Furancarboxylic acids are promising biobased building blocks in pharmaceutical and polymer industries. In this work, dual-enzyme cascade systems composed of galactose oxidase (GOase) and alcohol dehydrogenases (ADHs) are constructed for controlled synthesis of 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF), based on the catalytic promiscuity of ADHs. The byproduct H 2 O 2 , which is produced in GOase-catalyzed oxidation of HMF to 2,5-diformylfuran (DFF), is used for horseradish peroxidase (HRP)-mediated regeneration of the oxidized nicotinamide cofactors for subsequent oxidation of DFF promoted by an ADH, thus implementing H 2 O 2 internal recycling. The desired products FFCA and FDCA are obtained with yields of more than 95 %., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Catalytic lignosulfonate valorization is hampered by the in situ liberation of sulfur that ultimately poisons the catalyst. To overcome this limitation, metal sulfide catalysts were developed that are able to cleave the C-O bonds of lignosulfonate and are resistant to sulfur poisoning. The catalysts were prepared by using the lignosulfonate substrate as a precursor to form well-dispersed carbon-supported metal (Co, Ni, Mo, CoMo, NiMo) sulfide catalysts. Following optimization of the reaction conditions employing a model substrate, the catalysts were used to generate guaiacyl monomers from lignosulfonate. The Co catalyst was able to produce 23.7 mg of 4-propylguaiacol per gram of lignosulfonate with a selectivity of 84 %. The catalysts operated in water and could be recycled and reused multiple times. Thus, it was demonstrated that an inexpensive, sulfur-tolerant catalyst based on an earth-abundant metal and lignosulfonate efficiently catalyzed the selective hydrogenolysis of lignosulfonate in water in the absence of additives., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Glucaric acid (GA) is a major value-added chemicals feedstock and additive, especially in the food, cosmetics, and pharmaceutical industries. The increasing demand for GA is driving the search for a more efficient and less costly production pathway. In this study, a new in vitro multi-enzyme cascade system was developed, which converts sucrose efficiently to GA in a single vessel. The in vitro system, which does not require adenosine triphosphate (ATP) or nicotinamide adenine dinucleotide (NAD + ) supplementation, contains seven enzymes. All enzymes were chosen from the BRENDA and NCBI databases and were expressed efficiently in Escherichia coli BL21(DE3). All seven enzymes were combined in an in vitro cascade system, and the reaction conditions were optimized. Under the optimized conditions, the in vitro seven-enzyme cascade system converted 50 mm sucrose to 34.8 mm GA with high efficiency (75 % of the theoretical yield). This system represents an alternative pathway for more efficient and less costly production of GA, which could be adapted for the synthesis of other value-added chemicals., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The use of natural deep eutectic solvents (NADES) as multifunctional solvents for limonene bioprocessing was reported. NADES were used for the extraction of limonene from orange peel wastes, as solvent for the chemoenzymatic epoxidation of limonene, and as sacrificial electron donor for the in situ generation of H 2 O 2 to promote the epoxidation reaction. The proof-of-concept for this multifunctional use was provided, and the scope and current limitations of the concept were outlined., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Lignosulfonate is a byproduct of the sulfite pulping process and has limited use in industry. The main objective of this study was to investigate the carboxyethylation of lignosulfonate to increase its charge density to broaden its applications. The carboxyethylation of lignosulfonate was optimized under the conditions of 30 wt % NaOH, 2.0 mol mol -1 2-chloropropinic acid/lignosulfonate, 90 °C, 0.5 h, and 0.03 mol 2-chloropropinic acid, which produced carboxyethylated lignosulfonate with a charge density and molecular weight of -3.51 meq g -1 and 46 493 g mol -1 , respectively. The mechanism of the carboxyethylation reaction using 2-chloropropinic acid by an S N 1 pathway in an alkaline solution was discussed. Methylation was also used to mask the phenolic hydroxide groups of lignosulfonate to investigate if carboxyethylation occurred on aliphatic hydroxide groups of lignosulfonate. The produced carboxyethylated lignosulfonate was characterized by using FTIR spectroscopy, NMR spectroscopy, gel permeation chromatography, and elemental and functional group analyses. Basic 1 H- 1 H 2 D COSY NMR spectroscopy was used to record the coupled spins of the carboxyethyl group on carboxyethylated lignosulfonate. The information from 1 D 1 H NMR and 2 D NMR COSY spectroscopy provided evidence for the existence of a 1-carboxyethyl group on the carboxyethylated lignosulfonate structure., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Electrocatalysts with a high efficiency and durability for the hydrogen evolution reaction (HER) hold tremendous promise for next-generation energy conversion. Among the state-of-art catalysts for HER, organic-inorganic hybrid nanosheets exhibit a great potential with the merits of high activity, good durability, and low cost. Nevertheless, there is no general method for the synthesis of binary metal phosphide hybrid nanosheet HER catalysts with a tunable morphology and composition. Herein, we report a facile approach for the synthesis of nanosheets consisting of a binary cobalt nickel phosphide hybrid with a hierarchically porous nanostructures using an oxidation- phosphorization process. The as-optimized hybrid nanosheets annealed at 350 °C yield the highest pH-universal activity with overpotentials of 148, 111, and 173 mV in acidic, alkaline, and neutral media, respectively. Besides the promoted mass diffusion in the hierarchically porous structure, the extraordinary performance can be also attributed to the weakened adsorption of hydrogen as a result of the tunable composition of Co and Ni, which was revealed by first-principles calculations., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The utilization of biomass sugars has received great interesting recently. Herein, we present a highly efficient hybrid solar biomass fuel cell that utilizes thermal- and photocatalysis of solar irradiation and converts biomass sugars into electricity with high power output. The fuel cell uses polyoxometalates (POMs) as photocatalyst to decompose sugars and capture their electrons. The reduced POMs have strong visible and near-infrared light adsorption, which can significantly increase the temperature of the reaction system and largely promotes the thermal oxidation of sugars by the POM. In addition, the reduced POM functions as charge carrier that can release electrons at the anode in the fuel cell to generate electricity. The electron-transfer rates from glucose to POM under thermal and light-irradiation conditions were investigated in detail. The power outputs of this solar biomass fuel cell are investigated by using different types of sugars as fuels, with the highest power density reaching 45 mW cm -2 ., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Endowing materials with chirality and exploring the responses of the material under circularly polarized light (CPL) can enable further insight into the physical and chemical properties of the semiconductors to be gained, thus expanding on optoelectronic applications. Herein a bioinspired mesoporous chiral nematic graphitic carbon nitride (g-C 3 N 4 ) for efficient hydrogen evolution with polarized light modulation based on chiral nematic cellulose nanocrystal films prepared through silica templating is described. The mesoporous nematic chiral g-C 3 N 4 exhibits an ultrahigh hydrogen evolution rate of 219.9 μmol h -1 (for 20 mg catalyst), corresponding to a high enhancement factor of 55 when compared to the bulk g-C 3 N 4 under λ>420 nm irradiation. Furthermore, the chiral g-C 3 N 4 material exhibits unique photocatalytic activity modulated by CPL within the absorption region. This CPL-assisted photocatalytic regulation strategy holds great promise for a wide range of applications including optical devices, asymmetric photocatalysis, and chiral recognition/separation., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ionic liquids are used to dewater a suspension of birch Kraft pulp cellulose nanofibrils (CNF) and as a medium for water-free topochemical modification of the nanocellulose (a process denoted as "WtF-Nano"). Acetylation was applied as a model reaction to investigate the degree of modification and scope of effective ionic liquid structures. Little difference in reactivity was observed when water was removed, after introduction of an ionic liquid or molecular co-solvent. However, the viscoelastic properties of the CNF suspended in two ionic liquids show that the more basic, but non-dissolving ionic liquid, allows for better solvation of the CNF. Vibrio fischeri bacterial tests show that all ionic liquids in this study were harmless. Scanning electron microscopy and wide-angle X-ray scattering on regenerated samples show that the acetylated CNF is still in a fibrillar form. 1 D and 2 D NMR analyses, after direct dissolution in a novel ionic liquid electrolyte solution, indicate that both cellulose and residual xylan on the surface of the nanofibrils reacts to give acetate esters., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The catalytic promiscuity of hemoglobin (Hb) was explored for regenerating oxidized nicotinamide cofactors [NAD(P) + ]. With H 2 O 2 as oxidant, Hb efficiently oxidized NAD(P)H into NAD(P) + within 30 min. The new NAD(P) + regeneration system was coupled with horse liver alcohol dehydrogenase (HLADH) for the oxidation of bio-based furanics such as furfural and 5-hydroxymethylfurfural (HMF). The target acids (e.g., 2,5-furandicarboxylic acid, FDCA) were prepared with moderate-to-good yields. The enzymatic regeneration method was applied in l-glutamic dehydrogenase (DH)-mediated oxidative deamination of lglutamate and for l-lactic-DH-mediated oxidation of l-lactate, which furnished α-ketoglutarate and pyruvate in yields of 97 % and 81 %, respectively. A total turnover number (TTON) of up to approximately 5000 for cofactor and an E factor of less than 110 were obtained in the bi-enzymatic cascade synthesis of α-ketoglutarate. Overall, a proof-of-concept based on catalytic promiscuity of Hb was provided for in situ regeneration of NAD(P) + in DH-catalyzed oxidation reactions., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Given the shortage of sustainable resources and the increasingly serious environmental issues in recent decades, the demand for clean technologies and sustainable feedstocks is of great interest to researchers worldwide. With regard to the fields of energy saving and environmental remediation, the key point is the development of efficient catalysts, not only in terms of facile synthesis methods, but also the benign utilization of such catalysts. This work reviews the use of metal-organic frameworks (MOFs) and MOF-based materials in these fields. The definition of MOFs and MOF-based materials will be primarily introduced followed by a brief description of the characterization and stability of MOF-related materials under the applied conditions. The greening of MOF synthesis processes will then be discussed and catalogued by benign solvents and conditions and green precursors of MOFs. Furthermore, their suitable application in sustainable catalysis will be summarized, focusing on several typical atom-economic reactions, such as the direct introduction of H 2 or O 2 and C-C bond formation. Approaches towards reducing CO 2 emission by MOF-based catalysts will be described with special emphasis on CO 2 fixation and CO 2 reduction. In addition, driven by the explosive growth of energy consumption in the last century, much research has gone into biomass, which represents a renewable alternative to fossil fuels and a sustainable carbon feedstock for chemical production. The advanced progress of biomass-related transformations is also illustrated herein. Fundamental insights into the nature of MOF-based materials as constitutionally easily recoverable heterogeneous catalysts and as supports for various active sites is thoroughly discussed. Finally, challenges facing the development of this field and the outlook for future research are presented., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lignin structural studies play an essential role both in understanding the development of plant cell walls and for valorizing lignocellulosics as renewable biomaterials. Dimeric products released by selectively cleaving β-aryl ether linkages between lignin units reflect the distribution of recalcitrant lignin units, but have been neither absolutely defined nor quantitatively determined. Here, 12 guaiacyl-type thioacidolysis dimers were identified and quantified using newly synthesized standards. One product previously attributed to deriving from β-1-coupled units was established as resulting from β-5 units, correcting an analytical quandary. Another longstanding dilemma, that no β-β dimers were recognized in thioacidolysis products from gymnosperms, was resolved with the discovery of two such authenticated compounds. Individual GC response factors for each standard compound allowed rigorous quantification of dimeric products released from softwood lignins, affording insight into the various interunit-linkage distributions in lignins and thereby guiding the valorization of lignocellulosics., (© 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS] 3 PW 12 O 40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of monobenzoporphyrins (WH1-WH4) bearing different conjugated spacer groups were designed and synthesized as sensitizers for dye-sensitized solar cells. Although a phenyl spacer only has a minimal impact on the absorption bands of the monobenzoporphyrin, an ethynylphenyl (WH3) or a vinyl (WH4) spacer redshifts and broadens the absorption bands of the dyes to result in much enhanced light-harvesting ability. Dye-sensitized solar cells based on these monobenzoporphyrin dyes displayed remarkable differences in power conversion efficiencies (PCEs). The monobenzoporphyrin bearing no spacer (WH1) resulted in a PCE of only 0.5 %; in contrast, the monobenzoporphyrin bearing vinyl spacers (WH4) achieved a PCE of 5.2 %. The high efficiency of the WH4 cell is attributed to the higher light-harvesting ability, the lesser extent of aggregation on the TiO2 surface, and the more favorable electron-density distributions of the HOMO and LUMO for electron injection and collection. This work demonstrates the exceptional tunability of benzoporphyrins as sensitizers for dye-sensitized solar cells., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The effects of different alkaline pretreatments on cellulose structural features and accessibility are compared and correlated with the enzymatic hydrolysis of Populus. The pretreatments are shown to modify polysaccharides and lignin content to enhance the accessibility for cellulase enzymes. The highest increase in the cellulose accessibility was observed in dilute sodium hydroxide, followed by methods using ammonia soaking and lime (Ca(OH)2 ). The biggest increase of cellulose accessibility occurs during the first 10 min of pretreatment, with further increases at a slower rate as severity increases. Low temperature ammonia soaking at longer residence times dissolved a major portion of hemicellulose and exhibited higher cellulose accessibility than high temperature soaking. Moreover, the most significant reduction of degree of polymerization (DP) occurred for dilute sodium hydroxide (NaOH) and ammonia pretreated Populus samples. The study thus identifies important cellulose structural features and relevant parameters related to biomass recalcitrance., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)