Sustainable Carbon Materials Research Articles

The effects of lignin structure on the multiscale properties and electrochemical performance of activated carbons

Lignin is a nature’s wonder most abundant aromatic biopolymer and a promising precursor for a wide range of sustainable carbon materials (CMs). However, the effects of lignin structural heterogeneity on the properties and performance of lignin-based CMs are still poorly understood. In this paper, we address the influence of the lignin structural heterogeneity on the properties of lignin-based activated carbons (ACs). Taking two structurally different kraft (KL) and hydrolysis (HL) lignins, we show that they result into ACs with different properties and electrochemical performance in supercapacitor application. In similar carbonization and activation conditions, ACs from HL showed higher specific capacitances than ACs from KL. The difference between the two groups of ACs could not be solely attributed to the difference in their specific surface areas. They were rather found to result from different particle morphologies, pore size distributions, pore wall nanostructures, and surface chemistries, as revealed by multivariate data analyses. Moreover, we observed that KL and HL had different thermophysical behaviors and reactivities during the thermal treatment, which would have influenced the porosity development and surface oxygenation levels and consequently the electrochemical performance of the derived ACs. This work also shows that it is possible to engineer ACs from HL with electrochemical performance close to the commercial YP-50F Kuraray AC, which implies that less pure, carbohydrate-containing lignins are no less advantaged compared to purer KL to produce high-performance ACs for supercapacitor application.

N-doped sponge-like biochar: A promising CO2 sorbent for CO₂/CH₄ and CO2/N₂ gas separation

Sponge-like biochar sorbents were prepared from the dissolution of chitosan followed by freeze-drying methodology and pyrolysis at three different temperatures (400, 600, and 800 °C) to produce sustainable N-enriched carbon materials with enhanced CO2 uptake from CO2/CH4 and CO2/N2 gas mixtures. The pyrolysis process was reproduced by operando TGA-IR to study the gas evolved from the pyrolysis process. It was found that the pyrolysis temperature highly influences the textural properties of the chitosan sponge-like biochar materials, impacting mainly the amount and type of the N-species on the sample but also at the microporosity. XPS revealed the transformation of the amino groups from chitosan into pyridinic-N, pyrrolic-N, graphitic center-N, and graphitic valley-N or pyridine-N oxide species during the pyrolysis process. Increasing the pyrolysis temperature enhanced the quantity of the latter two N-type species. All sponge-like biochars adsorbed higher amounts of CO2 compared with CH4 and N2 gases, with maximum CO2 uptake (∼1.6 mmol⋅g−1) at 100 kPa and 25 °C for the sample pyrolyzed at 600 °C (named CTO_P600). Biochar produced at 800 °C showed no longer adsorption capacity for CH4 and N2, having the highest selectivity value for CO2/N2 separation under continuous flux conditions among all prepared biochar sorbents. Isobaric CO2 adsorption measurements on the CTO_P600 sorbent revealed that physisorption phenomena predominantly governed the CO2 adsorption process, which was confirmed by its consistent adsorption capacity after 10 consecutive adsorption–desorption cycles. Moreover, the biochar exhibited tolerance to water vapor adsorption, indicating its suitability to work under moisture-rich conditions.

N/S co-doped carbon nanosheets derived from sugarcane processing by-products for flexible solid-state supercapacitors

Developing sustainable carbon materials from biomass for supercapacitors is a promising solution to alleviate energy and environmental pressures. In this paper, novel N/S co-doped carbon nanosheets derived from sugarcane processing by-products are proposed. Flexible and binder-free electrodes based on carbon felt and sulfonated potassium fulvic acid were prepared by a simple impregnation-carbonization method. The maximum areal specific capacitance, power density and energy density of the symmetric supercapacitor are 409.9 mF cm−2 (1 mA cm−2), 0.92 mW cm−2 and 184.5 μWh cm−2, respectively. The operating voltage of the device increases to 1.8 V by using LiCl electrolyte. After 10,000 cycles, the capacitance remains 90 % of its initial value. Besides, the device possesses good flexibility, which can be bent at different angles and has a capacitance retention of 92.3 % after 5000 bending cycles. The supercapacitor is of great significance for the recovery of crop processing by-products to prepare flexible electronic devices.

Biomass-derived carbon material as efficient electrocatalysts for the oxygen reduction reaction

Despite the abundance of carbon in nature, a significant portion of the existing biomass carbon materials in livestock, agriculture, and marine fishery industry are currently being wasted. Utilizing sustainable carbon materials as an alternative to noble Pt-based catalysts is crucial step to convert widely available and low-cost biomass resources into clean energy systems. Therefore, the rational synthesis of carbon-based catalysts for oxygen reduction reaction (ORR) has become a hot research focus in the field of electrochemistry. In this study, the recent progress in the synthesis of ORR electrocatalysts using sustainable biomass resources was reviewed; the activation and synthesis strategies of various biomass resources, as well as the microstructure and oxygen reduction performance of the prepared carbon-based catalysts were investigated. It is hoped that this review article will promote the understanding of various parameters from biomass as precursors for catalyst preparation and make contribute to the transition of biomass resources from the wasted carbon materials to the main catalysts in future energy devices.

Advanced sustainable carbon material from babassu biomass and its adsorption performance

Activated carbon (AC) wasprepared from babassu mesocarp, an abundant biomass inBrazil. Thermal pretreatments, including hydrothermal carbonization and pyrolysis at different temperatures were applied along with potassium hydroxide activation, in synthesizing ACs with varying structure, electronic and surface properties. A thorough characterization of the ACs revealed their low structural order and high specific surface area, containing micropores and mesopores. Furthermore, negatively charged surface oxygen functional groups make them potential candidates as adsorbents for cationic chemical species. A detailed study of adsorption of methylene blue cationic dye was carried out by varying time, initial concentration, pH and ionic strength of the dye solution, which showed that the chief driving force of this adsorption is the Coulombic interaction on the surface, followed by diffusion throughout the pores. These ACsshowed fast and efficient dye uptake – the best sample showedequilibrium adsorption capacity of 388 mg g−1for methylene blueand 220 mg g−1 for another cationic dye crystal violetduring 6 h –and thereby can be used as renewable and sustainable adsorbents.

Pore structure regulation of hierarchical porous agaric-derived carbon via boric acid activation for supercapacitors

The development of sustainable carbon materials from biomass for electric double-layer supercapacitors is a promising solution to alleviate energy and environmental pressures. The electrochemical performance of biomass-derived carbon materials is greatly affected by their hierarchical porous structure. In general, the pore structure of biomass-derived carbon activated using chemical method is dominated by micropores with few mesopores. This hinders the transmission of electrolyte ions, thus limiting the electrochemical properties. Here we have designed a green unique boric acid-assisted method to synthesize hierarchical porous agaric-derived carbon. Benefiting from the unique hygroscopic recovery characteristics of agaric, boric acid can enter the interior of the agaric and act as a novel activator to effectively adjust the pore structure of porous carbon. During the carbonization process, the melted boron oxide with high viscosity and excellent wetting properties adheres to the agaric matrix as a template, which plays a key factor for increasing the mesopores (<4 nm) and promoting ions transport. The synthesized porous carbon has a high specific surface area (2279.5 cm 2 g −1 ), more reasonable hierarchical porous structure, abundant nitrogen atom doping (4.69 at.%) and high capacitance (502 F g −1 @ 0.5 A g −1 ). The symmetric supercapacitor tested in 1 M Na 2 SO 4 electrolyte has excellent performances. This optimization strategy provides a new idea to design more reasonable hierarchical porous biomass-derived carbon materials. • Synthesis of agaric-derived carbon using a green method of boric acid-assisted • The etching of boric acid increases pores in 1–4 nm. • Superior design of hierarchically porous structure promotes ions transport. • N-doped agaric-derived carbon has an excellent specific capacitance of 502 F g −1 .

Towards Sustainable Fuel Cells and Batteries with an AI Perspective

With growing environmental and ecological concerns, innovative energy storage systems are urgently required to develop smart grids and electric vehicles (EVs). Since their invention in the 1970s, rechargeable lithium-ion batteries (LIBs) have risen as a revolutionary innovation due to their superior benefits of high operating potential and energy density. Similarly, fuel cells, especially Proton Exchange Membrane Fuel Cells (PEMFC) and Solid-Oxide Fuel Cells (SOFC), have been developed as an energy storage system for EVs due to their compactness and high-temperature stability, respectively. Various attempts have been made to explore novel materials to enhance existing energy storage technologies. Materials design and development are significantly based on trial-and-error techniques and require substantial human effort and time. Additionally, researchers work on individual materials for specific applications. As a viewpoint, we present the available sustainable routes for electrochemical energy storage, highlighting the use of (i) green materials and processes, (ii) renewables, (iii) the circular economy approach, (iv) regulatory policies, and (v) the data driven approach to find the best materials from several databases with minimal human involvement and time. Finally, we provide an example of a high throughput and machine learning assisted approach for optimizing the properties of several sustainable carbon materials and applying them to energy storage devices. This study can prompt researchers to think, advance, and develop opportunities for future sustainable materials selection, optimization, and application in various electrochemical energy devices utilizing ML.

Carbon-Based Electrocatalyst Design with Phytic Acid-A Versatile Biomass-Derived Modifier of Functional Materials.

Increasing energy demands exacerbated by energy shortages have highlighted the urgency of research on renewable energy technologies. Carbon materials that can be employed as advanced electrodes and catalysts can increase the accessibility of efficient and economical energy conversion and storage solutions based on electrocatalysis. In particular, carbon materials derived from biomass are promising candidates to replace precious-metal-based catalysts, owing to their low cost, anti-corrosion properties, electrochemical durability, and sustainability. For catalytic applications, the rational design and engineering of functional carbon materials in terms of their structure, morphology, and heteroatom doping are crucial. Phytic acid derived from natural, abundant, and renewable resources represents a versatile carbon precursor and modifier that can be introduced to tune the aforementioned properties. This review discusses synthetic strategies for preparing functional carbon materials using phytic acid and explores the influence of this precursor on the resulting materials’ physicochemical characteristics. We also summarize recent strategies that have been applied to improve the oxygen reduction performance of porous carbon materials using phytic acid, thereby offering guidance for the future design of functional, sustainable carbon materials with enhanced catalytic properties.

Sustainable carbon materials from the pyrolysis of lignocellulosic biomass

Carbon materials with extremely variable properties are widely used in various fields such as energy and environment. The 21st century can be called the “super carbon era.” However, most of the synthesis pathways for carbon materials still rely on traditional fossil fuels, which will exacerbate the climate change issue. Biomass produced in nature is a sustainable source of carbon. Converting biomass to carbon materials is even a process of negative carbon emission, which can help alleviate the pressure of global warming. Pyrolysis is a simple but effective method to produce carbon materials from biomass. This review focuses on the production and functionalization of carbon materials produced by the pyrolysis of lignocellulosic biomass. The synthesis process and mechanism of lignocellulosic biomass-based carbon materials are reviewed, and the properties of the carbon materials (morphology, pore structure, surface area, and surface functional groups) are discussed. Moreover, we summarize the functionalization methods, including porous functionalization, N-doped functionalization, and metal-doped functionalization. At last, we propose the future prospects.

Decoupled temperature and pressure hydrothermal synthesis of carbon sub-micron spheres from cellulose

The temperature and pressure of the hydrothermal process occurring in a batch reactor are typically coupled. Herein, we develop a decoupled temperature and pressure hydrothermal system that can heat the cellulose at a constant pressure, thus lowering the degradation temperature of cellulose significantly and enabling the fast production of carbon sub-micron spheres. Carbon sub-micron spheres can be produced without any isothermal time, much faster compared to the conventional hydrothermal process. High-pressure water can help to cleave the hydrogen bonds in cellulose and facilitate dehydration reactions, thus promoting cellulose carbonization at low temperatures. A life cycle assessment based on a conceptual biorefinery design reveals that this technology leads to a substantial reduction in carbon emissions when hydrochar replacing fuel or used for soil amendment. Overall, the decoupled temperature and pressure hydrothermal treatment in this study provides a promising method to produce sustainable carbon materials from cellulose with a carbon-negative effect.

Biomass-Derived sustainable carbon materials in energy conversion and storage applications: Status and opportunities. A mini review

Electrochemical renewable energy technologies are receiving increasing attention for overcoming the serious energy crisis and environment deterioration. The versatile electrode materials, especially carbon-based hybrids play a decisive role in the adhibition of various energy conversion and storage equipments. Biomass-derived carbon materials occupy a pivotal position as the crucial electrode materials in emerging renewable energy devices, owing to their special electrochemical performance, environmental benignity and economic value. This brief review encompasses the recent achievements and representative synthesis strategies on application of sustainable biomass-derived carbon-based hybrids as electrode for energy equipments including catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), hydrogen evolution reaction (HER), metal–air batteries, supercapacitors (SCs), rechargeable batteries and so on. Then the significant role of defect-control, activation reagents, porosity, specific surface area and graphitic degree on the electrochemical activity is also studied in detail. This work will provide a valuable avenue of biomass-derived electrode hybrids for advanced energy conversion and storage technologies.

Advanced Sustainable Carbon Material from Babassu Biomass and its Adsorption Performance

Advanced Sustainable Carbon Material from Babassu Biomass and its Adsorption Performance

A multi-data-driven procedure towards a comprehensive understanding of the activated carbon electrodes performance (using for supercapacitor) employing ANN technique

Biomass resources are intensively used as economical and green-reserve precursor preparation of sustainable carbon materials used in supercapacitors. The synthetic processes of biomass-based precursors (BPs) are the most determinant proceedings for obtaining activated carbons (ACs) used in the electrode of energy storage devices. The AC-based electrode preparation and operational condition parameters can affect the capacitance performance of electrode. In the present work, the potential of Artificial Neural Network (ANN) modeling is assessed in interpreting how activation procedure, structural features, electrode synthesizing procedure, and operational condition can affect the capacitive performance of the carbon-based electrode. Radial Basis Function (RBF) model is established for the estimation of specific capacitance of biomass-based activated carbon (BAC) utilized in the electrode. Moreover, the algorithms used in RBF model performed accurate predictions of the model with the lowest error. Besides, employing the combination of quantitative and qualitative variables could perform a synergistic result. The multi-data could achieve a precise cognizance of materials participating in electrode preparation to obtain higher specific capacitance. The sensitivity analysis showed prominent effects of structural and operational characteristics (e.g. micropore to macropore carbon structure), molarity of electrolyte, binder ratio, and activation agent ratio, on Electric Double-layer capacitor performance.

Naturally nitrogen-doped porous carbon derived from waste crab shell as anode material for high performance sodium-ion battery

Transformation of biomass wastes into sustainable low-cost carbon materials is now a topic of great interest. Here, a novel porous carbon has been prepared through activation of crab shell, which demonstrates an interconnected hierarchical porosity comprised of macro-, meso- and micro-pores as well with a high specific surface area of 1153.6 m2 g−1. Benefiting from the unique pore structure and oxygen and nitrogen dual doping, a well-developed ionic and electronic conductivity is achieved. Remarkably, when used as a anode material for sodium-ion batteries, it exhibits good cycling stability with a capacity up to 339.1 mA h g−1 at a current density of 0.03 A g−1, and maintains a capacity of 132.4 mA h g−1 even at a high current density of 0.5 A g−1 after 200 cycles, and still maintain high Coulomb efficiency. These results indicate that the fabricated porous carbon could be a promising electrode material for sodium-ion batteries.

Sustainable Carbon Materials toward Emerging Applications.

It is desirable for a sustainable society that the production and utilization of renewable materials are net-zero in terms of carbon emissions. Carbon materials with emerging applications in CO2 utilization, renewable energy storage and conversion, and biomedicine have attracted much attention both academically and industrially. However, the preparation process of some new carbon materials suffers from energy consumption and environmental pollution issues. Therefore, the development of low-cost, scalable, industrially and economically attractive, sustainable carbon material preparation methods are required. In this regard, the use of biomass and its derivatives as a precursor of carbon materials is a major feature of sustainability. Recent advances in the synthetic strategy of sustainable carbon materials and their emerging applications are summarized in this short review. Emphasis is made on the discussion of the original intentions and various sustainable strategies for producing sustainable carbon materials. This review provides basic insights and significant guidelines for the further design of sustainable carbon materials and their emerging applications in catalysis and the biomedical field.

Metal oxide-doped activated carbons from bakery waste and coffee grounds for application in supercapacitors

The functionalization of sustainable carbon materials and their application in energy storage systems attract more and more relevancy. Bakery waste and spent coffee grounds were chosen as abundant organic residues and found to be suitable starting materials for hydrothermal carbonization and a subsequent chemical activation obtaining carbon contents of > 88%. In situ doping of the hydrochars during carbonization has proven to be a successful method for insertion of Fe2O3-, Fe3O4- and MnO2-Nanoparticles into the carbon matrix, supported by XRD analysis and SEM images. Chemical activation with K2CO3 led to iron contents up to 18% of iron and around 8% of manganese, respectively, in the corresponding activated carbon. Electrochemical characterization revealed overall higher specific capacitance for activated carbons derived from spent coffee grounds, with a highest of 87F*g−1. In contrast, the highest specific capacitance measured for activated carbons originated from bakery waste was 40,3F*g−1.

Breaking the lignin conversion bottleneck for multiple products: Co-production of aryl monomers and carbon nanospheres using one-step catalyst-free depolymerization

Lignin is considered as a renewable and sustainable resource for producing value-added aromatic chemicals and functional carbon materials. Herein, we develop a one-step catalyst-free depolymerization strategy to convert lignin into aryl monomers and carbon nanospheres simultaneously. Importantly, microwave-assisted depolymerization (MAD) in conjunction with dichloromethane (CH2Cl2) vapors is developed. The total mass yield of guaiacols reached the highest amount of 225.1 mg/g at 600 °C, and the highest yields of phenols (49.0 mg/g) and aromatic hydrocarbons (155.1 mg/g) were obtained at 700 °C. Hydrogen radicals and hydrogen chloride (HCl) are in-situ formed from CH2Cl2, significantly decreasing the activation barrier and reforming pyrolysis vapors to promote the formation of aryl monomers. Interestingly, uniform carbon nanospheres with an average size of 140 nm were produced as co-products at 700 °C. The microwave “hot-spots”, allied with the continuous surface erosion and the decrease in surface energy of lignin-derived carbon precursors by CH2Cl2 vapor, can be considered the driving force for the ultimate formation of carbon nanospheres. The CH2Cl2/MAD system produces aryl monomers (26.8 wt% yield) and carbon nanospheres (36.6 wt% yield) at 700 °C. We provide a facile, intriguing and scalable approach to convert lignin to valuable aryl monomers and sustainable carbon materials that can be applied in the chemistry, energy and environmental fields.

A Sustainable Carbon Material from Kraft Black Liquor as Nickel-Based Electrocatalyst Support for Ethanol Electro-Oxidation

The present work deals with a new methodology to produce a sustainable carbon material through a simple synthetic route, and its performance as Ni-based electrocatalyst support. Such porous carbon was easily synthesized from the raw Kraft black liquor, a by-product rich in lignin, by chemical polymerization in alkaline medium with a nickel source and subsequent activation by CO2. Nickel nanoparticles were homogeneously distributed in the samples, as revealed by STEM images. XPS analyses and BET method indicated the presence of Ni species in the synthesized material and a micro-mesoporous structure, respectively. The electrochemical characterization in NaOH and NaOH+ ethanol solutions showed that the as-prepared material has the relevant potential to be applied as electrocatalyst for Ethanol Oxidation Reaction (EOR) in alkaline medium.

Introduction of Phase Change Material into Sustainable Carbon Materials for Enhanced Shape Stability and Thermal Conductivity

AbstractNew sustainable carbon materials were synthesized from a low‐price and eco‐friendly carrot via hydrothermal reaction and carbonization approach. Afterwards, palmitic acid (PA) was impregnated into the carrot‐derived carbon material (CCM) to prepare PA@CCM composites through vacuum impregnation method. The thermal properties and shape stability of PA@CCM composites were evaluated by differential scanning calorimetry (DSC), thermal conductivity and thermal cycling tests. Owing to the special hybrid microstructure of the CCMs, the loading ratio of PA in PA@CCM composites could reach up to 85.3 % with the latent heat of 166.4 J g−1. More importantly, the PA@CCM composites show negligible leakage above the melting point of PA, exhibiting excellent shape stability. Compared with pristine PA, the thermal conductivity of PA@CCM composites could greatly enhanced by 145.5 %. Thus, PA@CCM composites can be considered as a promising candidate for thermal energy storage applications.

Effective carbon dioxide stabilization of nanofibers electrospun from raw coal tar and polyacrylonitrile

Non-fuel utilizations of coal for sustainable carbon materials production is certainly beneficial to the abatement of anthropogenic carbon dioxide emissions. Also, the technological uses of carbon dioxide are emergent to the earlier realization of the Paris Climate Agreement. This research was innovatively designed to produce carbon nanofibers from Wyoming Powder-River-Basin coal-derived supercritical extraction liquid (referred to raw coal tar) along with predetermined percentages of polyacrylonitrile by electrospinning, fiber stabilization with carbon dioxide, and subsequent carbonization treatment. The effects of raw coal tar additives to polyacrylonitrile nanofibers regarding the structural, textural and surface properties were investigated. Attenuated total reflection and diffuse reflectance infrared Fourier transform analyses reveal the difference in the dynamic evolution pathways of surface functional groups during the state-of-the-art oxygen-based and the new carbon dioxide-based fiber stabilization processes. In terms of mechanical properties, raw coal tar modifications give significant rise to the tensile strength of annealed polyacrylonitrile nanofibers, regardless of oxidative stabilization options. Additionally, the synergy of raw coal tar containing (30 wt %) polymeric precursor and carbon dioxide stabilization produces carbon nanofibers with a superior area-normalized electric double-layer capacitance of 1408.9 μF/cm2, which is approximately 4 times higher than the oxygen-stabilized pure polyacrylonitrile-derived ones.