Lignin-based Carbon Research Articles

Nickel-cobalt layer double hydroxide @ lignin-based hollow carbon quasi core-shell structure for high-performance supercapacitors

The physicochemical properties of an advanced supercapacitor electrode material can be co-tailored by incorporating various active materials into a hierarchical micro-/nano-architecture with a core-shell structure. Herein, we presented the development of high-performance supercapacitor electrode materials of quasi core-shell architectures based on nickel-cobalt layered double hydroxides supported on lignin-based hollow carbon (NiCoLDH@LHC) nanocomposites. The synthesis involves a novel approach combining enzymatic hydrolysis lignin (EHL) as a carbon source and magnesium oxide (MgO) as a template, utilizing evaporation-induced self-assembly (EISA) followed by carbonization. The manipulation of the mass ratio of NiCoLDH/LHC can induce alterations in its apparent morphology, stratified porosity, and active site, thereby an influence on its electrochemical performance. The optimal NiCoLDH@LHC90 nanocomposites display a unique flower-like spherical structure with open pores, a substantial specific surface area (SSA), and numerous electrochemically active sites. In addition, the density functional theory (DFT) calculations demonstrate that the higher density of Ni3+/Co3+ cations induced by the incorporation of LHC can increase the conductivity of NiCoLDH materials. Notably, these nanocomposites exhibit a remarkable specific capacitance of up to 640 C g−1 at 1 A g−1, with exceptional cycling stability (93.66% retention over 10,000 cycles). Furthermore, an assembled NiCoLDH@LHC90//LHC asymmetric supercapacitor demonstrates an impressive energy density (power density) of 35.44 Wh kg−1 (200.01 W kg−1). The physicochemical properties of an advanced supercapacitor electrode material can be finely tuned by incorporating various active materials into a hierarchical micro-/nano-architecture with a core-shell structure.

Rational Biomimetic Construction of Lignin-based Carbon Nanozyme for Identification of Uric Acid in Human Urine

Nanozymes have made remarkable progress in the field of sensing assays by replacing native enzyme functions. However, it is still a challenge to rationally design active centers from molecular structure to enhance the catalytic performance and develop low-cost nanozymes. In this work, guided by the catalytic site of horseradish peroxidase (HRP), iron source and histidine were coupled to the main chain of aminated sodium lignosulfonate (SL) through the self-assembly biomimetic strategy to construct His-SL-Fe with peroxidase activity. The inherent functional groups and basic framework of aminated SL provide a robust environment and promote the formation of active sites. His-SL-Fe shows excellent robustness over multiple test cycles and has a strong affinity for the substrate compared to HRP. His-SL-Fe had been effectively integrated in the sensing system for catalytic detection of uric acid (UA) to achieve accurate recognition of UA in the range of 0.5–100 μM with the limit of detection as low as 0.18 μM. The recovery of human urine samples is in the range of 96.8%–106.1 % and the error is within 4 %. This work not only provides a new approach for the directed design of high-performance nanozymes, but also demonstrates promising ideas for the refined application of biomass resources.

Lignin-based porous carbon adsorbents for CO2 capture

This review covers the state-of-the-art in the production of lignin-based carbon adsorbents for CO2 capture, discussing lignin chemistry and properties, traditional synthesis approaches to emerging methods, and fundamentals for rational design.

Driving multicolor lignin-based carbon quantum dots into selective metal-ion recognition and photocatalytic antibiotic decomposition

Achieving a waste-treats-pollutant vision, rationally designed lignin valorization that encompasses a shining story of multicolor carbon dots is proposed to promote selective metal-ion sensing and photocatalytic antibiotic removal.

Heteroatom-doped lignin-derived carbon material: performance and application

This review summarizes the influence of heteroatom-doping on the physicochemical properties of lignin-based carbon, together with its electro-chemical property in batteries and capacitors and adsorption ability for the removal of pollutants.

Insights into novel lignin-based magnetic carbon enabling peroxymonosulfate activation for tetracycline removal: Performance, mechanism and application

Excellent and recyclable catalysts are essential for wastewater treatment by peroxymonosulfate (PMS)-based advanced oxidation processes. Herein, a novel lignin-based magnetic carbon Fe@CCL was fabricated as a heterogeneous catalyst to boost PMS activation in tetracycline (TC) degradation. Experiments collectively suggested that the TC removal efficiency could be achieved as 95.9% by Fe@CCL/PMS system in a wide value of pH 3–11. Among sundry reactive oxygen species (•OH, SO4•–, O2•– and 1O2) in reaction system, singlet oxygen 1O2 could be selectively generated and played a major contribution for TC degradation. Theoretical simulations demonstrated that the valence state transformation of Fe species distributed in carbon skeleton is the main reason for the generation of 1O2, while the Fe(Ⅱ)/Fe(Ⅲ) redox cycle and the electron transfer in Fe@CCL were evidently beneficial to the effective activation of PMS. In addition, Fe@CCL could be easily recovered by an external magnet from the reaction system, and the catalytic performance in TC removal could be well maintained after regeneration. This work proposes an approach in the construction of high-performance and sustainable magnetic catalysts for organic pollutants removal.

Enzymolytic Lignin-Derived N-S Codoped Porous Carbon Nanocomposites as Electrocatalysts for Oxygen Reduction Reactions.

Currently, the development of nonmetallic oxygen reduction reaction (ORR) catalysts based on heteroatomic-doped carbon materials is receiving increaseing attention in the field of fuel cells. Here, we used enzymolytic lignin (EL), melamine, and thiourea as carbon, nitrogen, and sulfur sources and NH4Cl as an activator to prepare N- and S-codoped lignin-based polyporous carbon (ELC) by one-step pyrolysis. The prepared lignin-derived biocarbon material (ELC-1-900) possessed a high specific surface area (844 m2 g-1), abundant mesoporous structure, and a large pore volume (0.587 cm3 g-1). The XPS results showed that ELC-1-900 was successfully doped with N and S. ELC-1-900 exhibited extremely high activity and stability in alkaline media for the ORR, with a half-wave potential (E1/2 = 0.88 V) and starting potential (Eonset = 0.98 V) superior to those of Pt/C catalysts and most non-noble-metal catalysts reported in recent studies. In addition, ELC-1-900 showed better ORR stability and methanol tolerance in alkaline media than commercial Pt/C catalysts.

Effect of hydrothermal pH values on the morphology of special microspheres of lignin-based porous carbon and the mechanism of carbon dioxide adsorption

The study reports the economic and sustainable syntheses of a lignin-based porous carbon (LPC) for CO2 capture application. The pH values of hydrothermal solution affected the polymerization and aromatization of spheroidization, with morphological changes from blocky to microsphere. In addition, the reliable mechanisms of CO2 adsorption were proposed by combining experiments with Gaussian16 simulations based on DFT. The electrostatic attraction of oxygen-containing functional groups and the diffusivity resistance of CO2 in the pores are the key factors for the CO2 adsorption. ​The carboxyl groups have the strongest electrostatic attraction to CO2. LPC-pH 1 has the highest carboxyl group content, possessing a CO2 adsorption capacity of up to 5.10 mmol/g at 0℃, 1 bar. Furthermore, CO2 diffusion resistance became a main factor as the adsorption temperature increases. The innovative combination of quantum chemical calculations and microscopic properties provides a viable pathway for an insight into the future control of lignin-based carbon formation.

Lignin-Derived Mesoporous Carbon for Sodium-Ion Batteries: Block Copolymer Soft Templating and Carbon Microstructure Analysis.

The demand for versatile and sustainable energy materials is on the rise, given the importance of developing novel clean technologies for transition to a net zero economy. Here, we present the synthesis, characterization, and application of lignin-derived ordered mesoporous carbons with various pore sizes (from 5 to approximately 50 nm) as anodes in sodium-ion batteries. We have varied the pore size using self-synthesized PEOn-b-PHAm block copolymers with different PEO and PHA chain lengths, applying the "soft templating" approach to introduce isolated spherical pores of 20 to 50 nm in diameters. The pore structure was evaluated by transmission electron microscopy (TEM), nitrogen physisorption, and small-angle X-ray scattering (SAXS). We report the microstructure analysis of such mesoporous lignin-based carbons using Raman spectroscopy and wide-angle X-ray scattering (WAXS). In comparison with nontemplated carbon and carbons templated employing commercial Pluronic F-127 and PIB50-b-PEO45, which created accessible channels and spherical pores up to approximately 10 nm in diameter, the carbon microstructure analysis revealed that templating with all applied polymers significantly impedes graphitization upon thermal treatment. Furthermore, the gained knowledge of similar carbon microstructures regardless of the type of template allowed the investigation of the influence of different pore morphologies in carbon applied as an anode material in sodium-ion batteries, supporting the previous theories in the literature that closed pores are beneficial for sodium storage while providing insights into the importance of pore size.

Sustainable lignin-based carbon fibre reinforced polyamide composites: Production, characterisation and life cycle analysis

This work presents the first production, characterisation and life cycle analysis of composite materials produced from injection moulded polyamide reinforced with short lignin-based carbon fibre (CF). To produce these composites many challenges associated with the production of lignin CF have been resolved through the utilisation of thermoplastic polyurethane blend with Alcell organosolv lignin. These CFs have been utilised to reinforce polyamide 66 (PA66) and their performance as a reinforcement have been compared with a textile grade PAN CF. Composites have been prepared using short CF and injection moulding with results compared in terms of interfacial interactions, and composite mechanical performance. It was found that lignin-based CF increases crystallinity in the PA66. The increased matrix affinity of the lignin-based CF may be attributed to increased oxygen on the lignin CF which has been retained from the lignin precursor fibre. When considering that the lignin CF reach equivalent diameter to the PAN CF, the mechanical properties of lignin based CF are comparable to that of PAN CF. Life cycle analysis modelling predicts that the replacement of PAN CF with lignin CF reduces the global warming potential by 54 % for these materials.

Synergistic effects of hierarchical porous structures and ultra-high pyridine nitrogen doping enhance the oxygen reduction reaction electrocatalytic performance of metal-free laminated lignin-based carbon

Construction of non-metallic biomass-carbon based catalysts for fuel cell air cathode applications has attracted great attention in recent years. In this work, a convenient and clean technique was developed to fabrication nitrogen-doped lignin-based hierarchical porous lamellar carbon (N-LHPC) via lignin as the carbon precursor, melamine/urea as the nitrogen source and ZnC2O4.2H2O as the chemical activator. The N-LHPC has a high specific surface area (491.5 m2 g−1) and macroporous/mesoporous/microporous structures. The nitrogen doping of N-LHPC can reach 16.37 wt%, with a high pyridinic nitrogen content of 41.39 at.%. N-LHPC exhibits a high half-wave potential (0.87 V) and a large limiting current density (5.75 mA cm−2) in 0.1 mol KOH media which is comparable to the commercial Pt/C catalysts. Furthermore, N-LHPC was assembled as air cathode catalyst for Zn-air batteries to evaluate its practical catalytic performance, and the power density was as high as 191 mW cm−2, which was superior to the 20 wt% Pt/C electrocatalyst. This research demonstrates that lignin is a promising carbon source for the fabrication of high catalytic activity and economical electrocatalysts for energy storage systems.

CoZn@N-ALC, highly-efficient magnetic Co nanoparticles anchored by lignin-based Nitrogen-doping carbon for hydrodeoxygenation of vanillin

The conversion of lignin-based platform compounds into valuable biofuels and chemicals through catalytic processes is an attractive approach for the efficient valorization of renewable lignocellulosic biomass. One such process is the hydrodeoxygenation (HDO) of lignin-based vanillin (VL) to produce 2-methoxy-4-methylphenol (MMP), which is a promising liquid fuel and intermediate for fine chemicals. However, the development of a cost-effective catalytic system with high activity and selectivity remains a challenge. In this study, we report the preparation of a highly-efficient magnetic Co nanoparticles catalyst, CoZn@N-ALC, using alkali lignin as an assembly macromolecular ligand, Zn as a sacrificial metal, and dicyandiamide as a nitrogen source before the pyrolysis process. Various characterization techniques, including powder X-ray diffraction (XRD), pyridine adsorption infrared spectroscopy (Py-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), isothermal nitrogen adsorption/desorption, and X-ray photoelectron spectroscopy (XPS), were employed to investigate the role of zinc and nitrogen in the construction process of CoZn@N-ALC and the influence of catalyst preparation conditions. The optimized CoZn@N-ALC catalyst demonstrated nearly 100 % conversion of VL, complete selectivity towards MMP, and easy separation from the aqueous HDO system. Structure-performance investigation and density functional theory (DFT) calculations suggest that the exceptional catalytic performance of this catalyst can be attributed to the selective adsorption of C=O bonds by abundant Co (111) active species and its Lewis acid sites. This work provides valuable insights into the rational design of efficient, non-noble metal nanoparticle catalysts based on alkali lignin for the conversion of lignin-based platform compounds.

Bidirectional pore-creating strategy towards lignin-based heteroatom-doped porous carbon for supercapacitors

Significant pursuits have been committed to manufacturing high-performance lignin carbon-based supercapacitor electrode materials due to their high carbon content, abundant raw resources, and environmentally-friendly. However, the pessimistic accessible porous structure and appetency to the electrolyte of electrode materials are two vital factors for restricting its performance. Here, a bidirectional pore-creating strategy is proposed to construct heteroatom-doped lignin-based porous carbon (HLPC) materials with a high electrochemical active area at supramolecular-level. In this process, activated-mediates with different pore-forming functions are assembled into lignin-based supramolecules by electrostatic forcing, and then hierarchical pore-creation and heteroatom doping are accomplished simultaneously in the pyrolysis process. The obtained carbon materials possess a tunable specific surface area of 543.4–1502.3 m2 g−1 and high heteroatom content of 9.4–16.2 at.%. Benefit from its admirable physicochemical properties, the HPLCs deliver a high ions appetency, ultrahigh capacitance of 380.5 F g−1 at 0.2 A g−1, and extremely long cyclic stability (100% after 10,000 cycles), which is superior 2.5-fold than that of YP-80F at the same mass loading. More promising, symmetrical electrode devices based on HLPCs possess a preeminent energy density of 30.0 Wh kg−1 in aqueous electrolyte. Overall, this protocol provides a new avenue for promoting the advancement of electrode materials in industrial-scale supercapacitors and manufacturing high-value-added products from plentiful bio-waste.

A hydrophilic Lignin-Based carbon fiber sizing agent assembled with CNTs towards strengthening epoxy resin

The sizing agent has attracted growing attention to improve the interfacial compatibility of carbon fiber reinforced epoxy resin composites (CF/EP), but suffered from poor interfacial adhesion and environmental problems. Here, a hydrophilic lignin-based sizing agent (OLBEDKC) with remarkable storage stability and sizing effect on CF was obtained by the modifying oxidized lignin rich in hydrophilic groups and compounding with carbon nanotubes (CNTs). After treatment with 2.5% OLBEDKC, the hairiness of the CF fabric was reduced by 73.5%, and the surface energy was increased by 43.7%. Moreover, the use of OLBEDKC in CF/EP composites can lead to an increase in their interlaminar shear strength (ILSS), interface shear strength (IFSS), flexural strength, and flexural modulus by 58.4%, 64.8%, 87.9%, and 24.6%, respectively, compared to those without sizing treatment. This increase is attributed to the π-π conjugation and hydrogen bonding among the OLBEDKC, CF, and EP. Furthermore, the mechanical interlocking between the sized CF and EP effectively enhances their interfacial strength. In summary, this study presents a promising and eco-friendly hydrophilic sizing agent based on lignin that possesses high storage stability and exhibits an excellent sizing effect for CF reinforced EP composites.

Preparation of flexible and binder-free lignin-based carbon nanofiber electrode materials by electrospinning in aqueous system

Abstract Lignin, as a widely distributed, renewable and environmentally friendly source of carbon, could been utilized for carbon nanofibers to not only maximize the usage of resources, but also expand the energy-related opportunities. In this research, flexible lignin-based carbon nanofibers are prepared by electrospinning lignin nanofibers in a new green aqueous solution of lignin and polyvinyl alcohol (PVA), which is then characterized by physical and chemical characterizations. The results reveal that optimal carbonization temperature of 800 °C shows great improvements on the structural properties of lignin-based carbon nanofibers, which can be applied as binder-free electric double layer capacitor (EDLC) electrodes with good flexibility. The 2032 type button battery has a superior electrochemical performance with a large specific capacitance of 217.2 F g−1 at a 0.2 A g−1 current density, and remarkable cyclic stability of 94.9 % capacitance retention even after 10,000 charge and discharge cycles, due to the abundance of mesoporous volume and large microporous surface area of lignin-based carbon nanofiber electrodes carbonized in 800 °C.

Use of lignin-based crude carbon dots as effective antioxidant for natural rubber

Rubber is widely recognized as an important material, whose irreplaceable applications range from damping materials to tires. Generally, rubber is vulnerable to oxidative degradation, leading to a deterioration in the material's performance. Therefore, antioxidants are often added to extend the service life of rubber. In this study, crude lignin-based carbon dots (CLCDs) were prepared by a simple hydrothermal treatment of lignin with H2O2 and triethylenetetramine. The thus prepared CLCDs exhibit excellent radical scavenging capability, and were incorporated into natural rubber with vinyl pyridine-styrene-butadiene terpolymer (VPR) as coupling agent. The results revealed that CLCDs could endow NR with excellent antioxidative performance. Interestingly, CLCDs even show superior antioxidant effect towards rubber compared to purified lignin-based carbon dots (PLCDs). This work provides a unique source of inspiration for the preparation of low-cost, highly effective CLCDs from plant biomass waste, most of lignin being used to produce steam and energy, with excellent antioxidant capability for rubber, which is beneficial for a green and sustainable world.

Two-Pronged Approach: Synergistic Tuning of the Surface and Carbon Core to Achieve Yellow Emission in Lignin-Based Carbon Dots.

In this study, yellow emissive lignin-based carbon dots (Y-CDs) were successfully prepared through a synergistic approach to adjust its surface and carbon core states. The lignin was initially effectively oxidized and carboxymethylated to impart abundant -COOH onto the precursor, which eventually adjusts the surface state of the CDs. Subsequently, α-naphthol was employed during the solvothermal treatment of lignin with the aim of elevating the sp2 domain content in the CDs and, thus, adjusting its carbon core state. The obtained Y-CDs possessed abundant carboxyl groups and nanoscale spherical shape with an average diameter of 5.21 nm. Meanwhile, the energy gap of Y-CDs was 2.46 eV and the optimal emission wavelength was 561 nm under the excitation wavelength of 410 nm. Synergistic adjusting carbon core and surface of the Y-CDs would alter the surface charge distribution and promote the delocalization of π electrons, and thus lead to a red shifting with the emission wavelength of 154 nm. Furthermore, a shape memory film with excellent recovery performance and fluorescent properties was designed by embedding the Y-CDs into polyvinyl alcohol (PVA) polymer. The incorporation of Y-CDs could impart the film with considerable high-value applications in the fields of intelligent sensing, biomedicine, and tissue engineering.

Effect of plasma treatment on electrochemical performance of lignin-based carbon fibers

The abundant and renewable nature of lignin obtained from wood renders it as a sustainable carbon resource for energy storage applications. However, their environmentally unfavorable processing conditions and limited energy storage performance prohibit the use of lignin-based carbon materials' use as supercapacitor electrodes. The material's properties require advancement to overcome the limitation of low specific capacitances. In this study, we report on the impact on the electrochemical performance of inherently hydrophobic lignin-based carbon fibers (LCF) by subjecting them to a mild plasma treatment. The electrode’s capacitance was thus increased by 20%, with better rate capability and energy-power performance (11 Wh/kg and 0.8 kW/kg) in the KOH electrolyte. The quantified improvements were attributed to the capacitive functional groups, and enhanced surface wettability, which increased ion accessibility to active surface area improving charge-transfer ability to the surface with more additional functional groups. Remarkably, the selected plasma conditions introduced mostly desirable functional groups that limited any parasitic faradaic reactions prone to affect the device's long-term cycling stability and self-discharge characteristics. Furthermore, the impact of different inherent and introduced oxygen surface functional groups, including COO−, COH, CO, and CO, on the capacitive performance of these fibers at different device conditions (such as cycling and electrochemical activation) was investigated in different aqueous electrolytes. To ensure environmental favorability, the electrospinning of lignin fibers was conducted using a high molecular fraction of lignin without the inclusion of any fossil-based co-spinning polymers.

Enhancement of Cr(VI) adsorption on lignin-based carbon materials by a two-step hydrothermal strategy: Performance and mechanism

Cr(VI) is a carcinogenic heavy metal that forms an oxygen-containing anion, which is difficult to remove from water by adsorbents. Here, industrial alkali lignin was transformed into a Cr(VI) adsorbent (N-LC) by using a two-step hydrothermal strategy. The characterization results of the adsorbent showed that O and N were uniformly distributed on the surface of the adsorbent, resulting in a favorable morphology and structure. The Cr(VI) adsorption of N-LC was 13.50 times that of alkali lignin, and the maximum was 326.10 mg g−1, which confirmed the superiority of the two-step hydrothermal strategy. After 7 cycles, the adsorption of N-LC stabilized at approximately 62.18 %. In addition, in the presence of coexisting ions, N-LC showed a selective adsorption efficiency of 85.47 % for Cr(VI), which is sufficient to support its application to actual wastewaters. Model calculations and characterization showed that N and O groups were the main active factors in N-LC, and CO, -OH and pyridinic-N were the main active sites. This study provides a simple and efficient method for the treatment of heavy metals and the utilization of waste lignin, which is expected to be widely applied in the environmental, energy and chemical industries.

Simple Preparation of Lignin-Based Phenolic Resin Carbon and Its Efficient Adsorption of Congo Red

Biomass porous carbon is a low-cost, environmentally friendly material with no secondary pollution and has great potential in the field of dye pollutant adsorption. In this work, we used lignin, a renewable resource abundant in nature, to completely replace phenol and develop a lignin-based phenolic resin carbon (LPFC) adsorbent with high dye removal capacity, high recyclability, and low production cost. The samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Then the effects of adsorbent dosage (1 g/L, 2 g/L, 3 g/L, 4 g/L, and 5 g/L), temperature (30 °C, 45 °C, and 60 °C), initial dye concentration (100, 200, 300, 400, 500, 600, 700, and 800 mg/L), and pH (3, 4, 6, 8, 10, and 12) on the adsorption capacity were investigated during the adsorption process. The experimental results showed that the pore structure of LPFC was richer and more graphitized than that of phenolic resin carbon (PFC). The adsorption performance of LPFC on CR was better than that of PFC. The adsorption characteristics of LPFC were investigated from the adsorption isotherm and kinetic perspectives. The Langmuir isothermal adsorption model and the proposed second-order kinetic model were able to fit the adsorption data better. The adsorption process preferred monolayer adsorption, and the proposed second-order model predicted a maximum adsorption capacity of 425.53 mg/g. After five cycles, the removal of CR by LPFC only decreased from 92.1 to 79.2%. It can be seen that LPFC adsorbents have great potential in the field of wastewater treatment and can effectively realize the high-value application of lignin.