Efficient Catalytic Upgrading of Ethanol to Higher Alcohols via Inhibiting C–C Cleavage and Promoting C–C Coupling over Biomass-Derived NiZn@NC Catalysts

Achieve full utilization of lignin, cellulose and hemicellulose from corn stover with amphiphilic polyoxometalate catalysts in a one-pot method

The innovative utilization of lignin, cellulose, and hemicellulose from waste biomass, such as corn stover, represents a significant advancement in converting renewable biomass into aromatic compounds and reducing sugars. The lignin-first concept represents a pivotal advancement in using lignocellulose as a value-added chemical. However, the intricate bonding patterns among the three major components of lignocellulose, coupled with hydrogen bonding at both intramolecular and intermolecular levels, pose considerable challenges in achieving efficient catalytic conversion. Consequently, a series of (STAC)nH5-nPMo10V2O40(n = 1-5) (STAC = stearyl trimethyl ammonium chloride, C21H46NCl) catalysts with amphiphilic micellar structures were designed and employed for the catalytic oxidation of corn stover. The catalysts demonstrated efficacy in cleaving the CC and CO bonds of lignin, attributable to the V-based oxidation center of the polyoxometalates. Moreover, the amphiphilic structure further potentiates the generation of aromatic monomer products during the lignin depolymerization. The lignin monomer was isolated with a yield of 24.41 % in 10 h at 130 °C utilizing the catalyst (STAC)2H3PMo10V2O40. Furthermore, the catalysts were utilized to convert hemicellulose and cellulose into sugars, achieving a 39.29 % yield of carbohydrate compounds at 170 °C in water, thereby highlighting the broad applicability and versatility. The exceptional recyclability and stability of these micellar-type catalysts allow them to retain high activity over 10 consecutive reuse cycles. Utilizing a one-pot approach with a lignin-first strategy, mediated by these catalysts, enables the comprehensive utilization and conversion of corn stover. This research establishes a robust framework for the advancement of renewable resource utilization and sustainable chemical processes.

Effect of hydrophobically-modified sulfonated lignin on thermal stability of disperse dye paste

This study aims to develop a lignin-based dispersant with excellent high-temperature dispersion properties by introducing cyclohexyl and phenyl hydrophobic groups into sulfomethylated lignin (SAL) molecules through a grafting modification strategy, thereby addressing the limitations of traditional disperse dye pastes in terms of grinding efficiency and thermal stability. The results show that graft-modified lignin dispersants outperform both SAL and the commercial dispersant Reax-85A. They not only improve the grinding efficiency of disperse dye pastes but also markedly enhance their thermal stability. The particle size of disperse dye paste significantly decreased from greater than 5 μm to 1 μm. The lignin dispersant containing cyclohexyl and phenyl groups significantly enhanced the hydrophobic van der Waals adsorption forces toward disperse dyes. Under high-temperature conditions, the prepared disperse dye pastes maintained excellent diffusion performance and thermal stability. QCM-D studies revealed that the adsorption capacity |ΔF| of hydrophobically-modified SAL on disperse dyes was significantly enhanced compared to that of SAL and Reax-85A, and it exhibited strong adsorption stability with minimal desorption, demonstrating robust adhesion to disperse dyes. Furthermore, the adsorption quantity of phenyl-modified SAL on disperse dyes was greater than that of cyclohexyl-modified SAL.

Molecular Weight Engineering Modulates Lignin-Metal Supramolecular Framework to Construct Carbon-Coated CoRu Alloy for Effective Overall Water Splitting

To overcome the challenges of low catalytic activity and instability, a molecular weight engineering strategy coupled with oxidative ammonolysis is developed to synthesize CoRu-based alloy catalysts with distinct morphologies and properties from biorefinery lignin. This approach effectively modulates intrinsic active sites and exposes unsaturated nitrogen-oxygen structures, thereby tailoring the morphology and defect structure of the carbon layers in the catalysts. The as-synthesized CoRu alloy catalysts from lignin precursors with varying molecular weights are designated as CoRu@OALC-EtOAC, CoRu@OALC-EtOH, and CoRu@OALC-Residual. CoRu@OALC-EtOAC, featuring a defect-rich graphitic carbon-coated CoRu alloy structure, exhibited exceptional overall water-splitting performance (1.48 V at 10 mA cm-2), significantly surpassing Pt/C || Ru/C (1.58 V at 10 mA cm-2). In contrast, CoRu@OALC-Residual, with its amorphous carbon-coated CoRu alloy structure, demonstrated remarkable stability (350 h at 100 mA cm-2), vastly outperforming Pt/C || Ru/C (6 h at 100 mA cm-2). In-situ Raman spectroscopy and DFT calculations revealed that the defect-rich carbon layers effectively adsorb *H intermediates, accelerating the catalytic process. This strong adsorption also induces carbon layer rearrangement, leading to its dissolution of the carbon layer and oxidation of CoRu metal particles. This strategy provides a universal method for biomass-derived catalysts, establishing a direct relationship between molecular weight, catalyst morphology, and electrocatalytic performance.

Interface Synergy of Exposed Oxygen Vacancy and Pd Lewis Acid Sites Enabling Superior Cooperative Photoredox Synthesis

Photo-driven cross-coupling of o-arylenediamines and alcohols has emerged as an alternative for the synthesis of bio-active benzimidazoles. However, tackling the key problem related to efficient adsorption and activation of both coupling partners over photocatalysts towards activity enhancement remains a challenge. Here, we demonstrate an efficient interface synergy strategy by coupling exposed oxygen vacancies (VO) and Pd Lewis acid sites for benzimidazole and hydrogen (H2) coproduction over Pd-loaded TiO2 nanospheres with the highest photoredox activity compared to previous works so far. The results show that the introduction of VO optimizes the energy band structure and supplies coordinatively unsaturated sites for adsorbing and activating ethanol molecules, affording acetaldehyde active intermediates. Pd acts as a Lewis acid site, enhancing the adsorption of alkaline amine molecules via Lewis acid-base pair interactions and driving the condensation process. Furthermore, VO and Pd synergistically promote interfacial charge transfer and separation. This work offers new insightful guidance for the rational design of semiconductor-based photocatalysts with interface synergy at the molecular level towards the high-performance coproduction of renewable fuels and value-added feedstocks.

Valorization of residual lignin from corncob residues into thermosensitive lignin-based "molecular glues" for recycling cellulase

The cost of enzymolysis is a major bottleneck for the industrialisation of lignocellulosic enzymatic hydrolysis technology, and recycling cellulase can reduce this cost. Herein, a sulfobetaine prepolymer (CPS) with terminal chlorine was grafted onto enzymatic hydrolysis residual lignin (EHL) from corncob to construct thermosensitive lignin-based "molecular glues" (lignin-based sulfobetaine polymers, L-CPS) that were used to recover and recycle cellulase. L-CPS2 (1.0 g/L) was added to the corncob residue (CCR) enzymolysis system (50 °C, pH 4.5). After hydrolysis, L-CPS2 co-precipitated with cellulase through hydrophobic binding when cooling to 25 °C. This co-precipitation decreased the amount of cellulase by 40 %. In summary, a thermally responsive lignin-based molecular glue was constructed for green recycling of cellulase, providing a new approach to decreasing the cost of lignocellulosic enzymolysis and high value utilisation of industrial lignin.

Lignin-assisted electronic modulation on NiSe/FeOx heterointerface for boosting electrocatalytic oxygen evolution reaction

The development of productive and durable non-precious metal catalysts for the sluggish oxygen evolution reaction (OER) is critical for water splitting. Herein, a novel NiSe-FeOx heterojunction encapsulated in lignin-derived carbon layer (NiSe-FeOx@LC) was synthesized via hydrothermal self-assembly and in-situ pyrolysis. NiSe-FeOx@LC exhibited excellent OER performance with an overpotential of 265 mV at 50 mA·cm-2, a Tafel slope of 83 mV·dec-1, as well as long-term stability. Both experimental and DFT calculation results indicated that the doping of FeOx into NiSe@LC successfully optimized the dual interface structure between NiSe and FeOx, thereby promoted the d-bands orbital hybridization, that facilitated electron transfer. Besides, the carbon coating effectively protected the NiSe-FeOx components from leaching and agglomerating during the reaction. This study provides insight into the significance of lignin-derived carbon-encapsulated metallic catalyst for electrocatalytic OER process.

Multifunctional Super-Hydrophilic MXene/Biomass Composite Aerogel Evaporator for Efficient Solar-Driven Desalination and Wastewater Treatment

Solar-driven interfacial evaporation is recognized as a sustainable and effective strategy for desalination to mitigate the freshwater scarcity issue. Nevertheless, the challenges of oil contamination, salt accumulation, and poor long-term stability of the solar desalination process limit its applications. Herein, a 3D biomass-based multifunctional solar aerogel evaporator is developed for water production with fabricated chitosan/lignin (CSL) aerogel as the skeleton, encapsulated with carbonized lignin (CL) particles and Ti3C2TiX (MXene) nanosheets as light-absorbing materials. Benefitting from its super-hydrophilic wettability, interconnected macropore structure, and high broadband light absorption (ca. 95.50%), the prepared CSL-C@MXene-20 mg evaporator exhibited a high and stable water evaporation flux of 2.351 kg m-2 h-1 with an energy conversion efficiency of 88.22% under 1 Sun (1 kW m-2) illumination. The CSL-C@MXene-20 mg evaporator performed excellent salt tolerance and long-term solar vapor generation in a 3.5 wt.% NaCl solution. Also, its super-hydrophilicity and oleophobicity resulted in superior salt resistance and anti-fouling performance in high salinity brine (20 wt.% NaCl) and oily wastewater. This work offers new insight into the manufacture of porous and eco-friendly biomass-based photothermal aerogels for advanced solar-powered seawater desalination and wastewater purification.

Biomass-Based Antibacterial Hybrid Engineering Hydrogel for Efficient Solar Steam Generation

Interfacial solar steam generation is recognized as a promising solution to alleviate the scarcity of freshwater resources owing to its utilization of clean solar energy alongside its high efficiency and minimal heat loss. Nonetheless, the utilization of solar energy for water evaporation encounters challenges, primarily manifested in low evaporation rates and efficiency. Herein, we introduced an approach involving the development of a biomass-based hybrid engineering hydrogel evaporator, denoted as CLC (chitosan and lignosulfonate sodium hybrid hydrogel with a carbon nanotube). The construction of this evaporator involves the straightforward blending of lignosulfonate sodium (LS) and marine polysaccharide biomass chitosan (CS) with carbon nanotubes (CNT) serving as the photothermal materials. The interaction between the sulfonic group of LS and the amino group of CS with water molecules, facilitated by hydrogen bonding and electrostatic interactions, reduces the evaporation enthalpy of water, thereby lowering the energy demand for evaporation. Furthermore, the incorporation of LS reduces the thermal conductivity of the as-prepared hydrogel and promotes photothermal management to mitigate heat loss. The CLC hydrogel demonstrates an evaporation rate of 2.48 kg m-2 h-1 and energy efficiency of 90% under one sun illumination. Moreover, the CLC hydrogel exhibits excellent antibacterial properties (98.4%), ensuring that desalinated water meets drinking standards. This high efficiency and eco-friendly biomass hydrogel with antibiological pollution characteristics and purification abilities holds great potential for widespread application of long-term seawater desalination.

A Co-based nitrogen-doped lignin carbon catalyst with high stability and wide operating window for rapid degradation of antibiotics

Co-based catalysts play a crucial role in the activation of peroxymonosulfate (PMS) for degradation contaminants. However, the practical application of such catalysts is hindered by challenges like the self-aggregation of Co nanoparticles and leaching of Co2+. In this study, the Co-based catalyst Co-N/C@CL was synthesized from carboxymethylated lignin obtained by grafting abundant carboxymethyl groups into alkali lignin, in which the presence of these carboxymethyl groups enhanced its water solubility and allowed the formation of stable macromolecular complexes with Co2+. This catalyst exhibited a high specific surface area (521.8 m2·g-1) and a uniform distribution of Co nanoparticles. Consequently, the Co-N/C@CL/PMS system could completely remove 20 ppm tetracycline (TC) in 2 min at a rate of 2.404 min-1. Experimental results and DFT calculations revealed that the synergistic effect of lignin carbon and Co NPs accelerated the cleavage and electron transfer of OO bonds, thus promoting the formation of 1O2, OH and SO4-, with 1O2 emerging as the predominant contributor. Moreover, Co-N/C@CL displayed excellent cycling stability and low Co2+ leaching. This work not only provides a feasible strategy for the preparation of highly active and stable Co-based carbon materials but also offers a promising catalyst for the efficient degradation of TC.

Enabling direct-growth route for highly efficient ethanol upgrading to long-chain alcohols in aqueous phase

Upgrading ethanol to long-chain alcohols (LAS, C6+OH) offers an attractive and sustainable approach to carbon neutrality. Yet it remains a grand challenge to achieve efficient carbon chain propagation, particularly with noble metal-free catalysts in aqueous phase, toward LAS production. Here we report an unconventional but effective strategy for designing highly efficient catalysts for ethanol upgrading to LAS, in which Ni catalytic sites are controllably exposed on surface through sulfur modification. The optimal catalyst exhibits the performance well exceeding previous reports, achieving ultrahigh LAS selectivity (15.2% C6OH and 59.0% C8+OH) at nearly complete ethanol conversion (99.1%). Our in situ characterizations, together with theoretical simulation, reveal that the selectively exposed Ni sites which offer strong adsorption for aldehydes but are inert for side reactions can effectively stabilize and enrich aldehyde intermediates, dramatically improving direct-growth probability toward LAS production. This work opens a new paradigm for designing high-performance non-noble metal catalysts for upgrading aqueous EtOH to LAS.

Lignocellulosic Biomass-Based Carbon Dots: Synthesis Processes, Properties, and Applications

Carbon dots (CDs), a new type of carbon-based fluorescent nanomaterial, have attracted widespread attention because of their numerous excellent properties. Lignocellulosic biomass is the most abundant renewable natural resource and possesses broad potential to manufacture different composite and smart materials. Numerous studies have explored the potential of using the components (such as cellulose, hemicellulose, and lignin) in lignocellulosic biomass to produce CDs. There are few papers systemically aiming in the review of the state-of-the-art works related to lignocellulosic biomass-derived CDs. In this review, the significant advances in synthesis processes, formation mechanisms, structural characteristics, optical properties, and applications of lignocellulosic biomass-based CDs such as cellulose-based CDs, hemicellulose-based CDs and lignin-based CDs in latest research are reviewed. In addition, future research directions on the improvement of the synthesis technology of CDs using lignocellulosic biomass as raw materials to enhance the properties of CDs are proposed. This review will serve as a road map for scientists engaged in research and exploring more applications of CDs in different science fields to achieve the highest material performance goals of CDs.

Synthesis of bifunctional thermal response promoters for improved high-solids enzymatic hydrolysis of corncob residues

The enzymatic hydrolysis cost of lignocellulose can be reduced by improving enzymatic hydrolysis and recycling cellulase by adding additives. A series of copolymers P(SSS-co-SPE) (PSSPs) were synthesized using sodium p-styrene sulfonate (SSS) and sulfobetaine (SPE) as monomers. PSSP exhibited upper critical solution temperature response. PSSP with high molar ratio of SSS displayed more significant improved hydrolysis performance. When 10.0 g/L PSSP5 was added to the hydrolysis system of corncob residues, and substrate enzymatic digestibility at 72 h (SED@72 h) increased by 1.4 times. PSSP with high molecular weight and moderate molar ratio of SSS, had significant temperature response, enhanced hydrolysis, and recovering cellulase properties. For high-solids hydrolysis of corncob residues, SED@48 h increased by 1.2 times with adding 4.0 g/L of PSSP3. Meanwhile, 50% of cellulase amount was saved at the room temperature. This work provides a new idea for reducing the hydrolysis cost of lignocellulose-based sugar platform technology.

Zinc Vacancy Promotes Photo-Reforming Lignin Model to H2 Evolution and Value-Added Chemicals Production

Lignin, rich in β-O-4 bonds and aromatic structure, is a renewable and potential resource for value-added chemicals and promoting H2 evolution. However, direct photo-reforming lignin remains a huge challenge due to its recalcitrant structure. Herein, a collaborative strategy is proposed by dispersing Pt on zinc-vacancy-riched ZnIn2 S4 (Pt/VZn -ZIS) for revealing the effect of lignin structure during photo-reforming process with lignin models. And a series of theoretical calculations and experimental results show that lignin model substances with more nucleophilic group structures will have a stronger tendency to occur the photo-reforming reactions. In addition, benefiting of Pt-S electronic channel is formed by occupying Pt atom onto zinc vacancies in ZnIn2 S4 , which can effectively reduce the energy barrier of H2 evolution and accompany the selective oxidation of lignin model from Cα-OH to Cα = O under simulated sunlight. The natural lignin is used to further demonstrate this selective oxidation mechanism. The presented work demonstrates the photo-reforming lignin model mechanism and the influence of lignin-structure during the process of photo-reforming.

Lignin-coordinated highly dispersed PdZn alloy nanocluster supported on N-doped nanolayer carbon and its application in hexavalent chromium detoxification

As a renewable and low-cost biomacromolecule with high aromaticity and carbon content, lignin is a promising raw material for preparation of versatile carbon materials. Herein, we present a facile one-pot approach to prepare PdZn alloy nanocluster catalysts supported on N-doped lignin-derived nanolayer carbon through facile pyrolysis of melamine-mixed lignin-Pd-Zn complex. The dispersion of the PdZn alloy nanoclusters could be effectively modulated by varying the addition of melamine and the molar ratio of Pd and Zn salts. PdZn alloy nanocluster catalysts (Pd-Zn₂₉@N₁₀C) with ultra-small particle size (about 0.47 nm) were prepared when 10 times of melamine (relative to lignin weight) was added and the molar ratio of Pd and Zn salts was 1:29. Thereby, the catalyst presented superior catalytic activity for reduction of Cr(VI) to harmfulless Cr(III), significantly better than the two references Zn@N₁₀C (without Pd addition) and Pd-Zn₂₉@C (without N doping), as well as the commercial Pd/C. In addition, thanks to the strong anchoring of the PdZn alloy on the N-doped nanolayer support, the Pd-Zn₂₉@N₁₀C catalysts also exhibited good reusability. Consequently, the current study provides a straightforward and feasible method for producing highly dispersed PdZn alloy nanoclusters by lignin coordination, and further demonstrates its excellent applicability in hexavalent chromium reduction.

Lignosulfonate-assisted in situ synthesis of Co9S8-Ni3S2 heterojunctions encapsulated by S/N co-doped biochar for efficient water oxidation

The development of highly active and stable earth-rich electrocatalysts remains a major challenge to release the reliance on noble metal catalysts in sustainable (electro)chemical processes. In this work, metal sulfides encapsulated with S/N co-doped carbon were synthesized with a one-step pyrolysis strategy, where S was introduced during the self-assembly process of sodium lignosulfonate. Due to the precise coordination of Ni and Co ions with lignosulfonate, an intense-interacted Co₉S₈-Ni₃S₂ heterojunction was formed inside the carbon shell, causing the redistribution of electrons. An overpotential as low as 200 mV was obtained over Co₉S₈-Ni₃S₂@SNC to reach a current density of 10 mA cm^-2. Only a slight increase of 14.4 mV was observed in a 50 h chronoamperometric stability test. Density functional theory (DFT) calculations showed that Co₉S₈-Ni₃S₂ heterojunctions encapsulated with S/N co-doped carbon can optimize the electronic structure, lower the reaction energy barrier, and improve the OER reaction activity. This work provides a novel strategy for constructing highly efficient and sustainable metal sulfide heterojunction catalysts with the assistance of lignosulfonate biomass.

Construction of PVA-lignosulfonate hydrogels for improved mechanical performances and all-in-one flexible supercapacitors

All-in-one supercapacitors are one of the best candidates for realizing flexible supercapacitors because of their outstanding flexibility and stability. The pursuit of improved electrochemical performance while meeting the requirements of flexible functionalization has always been a long-term goal. To this aim, lignosulfonate (LS) can be used in the field of all-in-one supercapacitors and contribute to its unique three-dimensional structure and abundant functional groups. By doping a small amount of LS, a simple approach is developed to achieve a one-step improvement in electrochemical performance and flexible functional design in this study. PVA-lignosulfonate hydrogel (PLH) obtains a compact and regular three-dimensional porous structure, higher ionic conductivity (0.17 S/cm), bending flexibility, and compression resistance. Polyaniline (PANI) based solid-state supercapacitors PANI-PVA and PANI-PLH show specific capacitance values of 505 and 558 mF/cm², respectively, at a current density of 0.5 mA/cm². After 5000 charge-discharge cycles, the capacitance retention rate increases from 53 % to 73 %, and the PANI-PLH can maintain the stability of electrochemical performance under bending, folding, puncturing, and squeezing. After 1600 times folding, the capacity remains almost 100 %. This study presents a one-step optimization for the construction of functional and high-performance all-in-one supercapacitors in a simple way and a novel idea for the potential application of the high-value lignin.

Synthesis of Sulfonated Carbon from Discarded Masks for Effective Production of 5-Hydroxymethylfurfural

5-hydroxymethylfurfural (HMF), as one of the top ten important platform chemicals, can be used to produce 2,5-furandicarboxylic acid (FDCA), 2,5-dimethyl furan (DMF), levulinic acid, and other chemicals. An environmentally friendly system for the synthesis of sulfonated carbon materials from discarded masks has been proposed. A series of mask-based solid acid catalysts (bMC-SO3H) were prepared by a simple two-step process. Mechanochemical pretreatment (ball milling) of waste mask and sulfonated group precursor, followed by thermal carbonization under nitrogen gas, were used to synthesize sulfonated porous carbon. The total acid amount of the prepared bMC-SO3H was measured by the Boehm method, which exhibited 1.2–5.3 mmol/g. The addition of the sulfonated group precursor in the mechanochemical treatment (ball milling) process caused intense structure fragmentation of the discarded masks. These sulfonated porous carbons (bMC(600)-SO3H) as solid acid catalysts achieved fructose conversion of 100% and HMF yield of 82.1% after 120 min at 95 °C in 1-butyl-3-methylimidazolium chloride. The bMC-SO3H could be reused five times, during which both the HMF yield and fructose conversion were stable. This work provides a strategy for the synthesis of sulfonated carbon from discarded masks and efficient catalyzed fructose upgrading to HMF.