Functional Carbon Materials Research Articles

Biomass-derived functional carbon material for CO2 adsorption and electrochemical CO2 reduction reaction

CO2 adsorption and electrocatalytic CO2 reduction (CO2RR) have been considered a promising path to realize CO2 emission reduction and simultaneously producing value-added chemicals. However, the high price and unsatisfactory performance of adsorbent or electrocatalyst materials have limited their application. Our group focuses on developing high-performance carbon materials derived from biomass for efficient CO2 adsorption and CO2RR. The effect of pyrolytic parameter and modifying agents was systematically studied to figure out the formation mechanism of biomass-derived carbon material. Furthermore, the mechanism CO2 adsorption and CO2RR are explored to determine required physicochemical properties of these carbon materials. Notably, in order to precisely introduce the desired pore structure and functional groups onto material, the idea of combining adjustable and modifiable metal-organic frameworks (MOFs) with environmentally friendly and stable biomass was proposed. The challenge in the application of biomass-derived functional carbon material is clarified. Through researchers are constantly dedicated to this field of research, it is believed that biomass-derived carbon material will find their unique positions in helping achieving carbon neutral.

A general strategy for direct growth of yolk-shell MOF-on-MOF hybrids

Construction of metal–organic framework (MOF) hybrids with yolk-shell nanostructures via MOF-on-MOF growth is significant for MOF design toward elaborate properties and enhanced performances, while remains challenging. Here, we report the direct growth of yolk-shell MOF-on-MOF hybrids via an interfacial growth-reorganization strategy. The synthesis relies on the precise growth of guest CoZn-ZIF (ZIF = zeolite imidazole framework) with appropriate crystal diameter and arrangement on host MOFs, inducing an in-situ transformation of core–shell intermediate into yolk-shell product. This strategy can be generally applied to the growth of CoZn-ZIF onto various host MOFs with different shapes, crystal structures and compositions including rod-like and octahedral Fe-based NH2-MIL-88B (MIL = Material Institute Lavoisier) and cake-like Ti-based NH2-MIL-125 toward three kinds of yolk-shell MOF-on-MOF hybrids. Moreover, functional carbon materials with bridged yolk-shell architecture can be prepared by pyrolysis of MOF-on-MOF hybrids as precursors, exhibiting enhanced oxygen reduction reaction performance than their monomeric counterparts. Our work paves the way for the design and application of MOF based yolk-shell nanostructures.

Efficient electrochemical energy storage designed by second alcoholic fermentation of rice

Supercapacitors can deliver energy quickly, offering extraordinary potential for efficient electrochemical energy storage (EES) systems. Specifically, carbon-based supercapacitors have reliable operational stability and outstanding cycle lifespans. However, designing low-cost and high-energy-density carbon electrode materials using a simple method remains an enormous challenge. Here, we design a porous carbon material JKPC-4-700 derived from a second alcoholic fermentation rice by tuning the pore sizes using a simple approach. The main pore sizes of JKPC-4-700 are 0.57 and 1.22 nm, in good agreement with the 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid. The specific surface area of JKPC-4-700 reaches 2662 m2 g−1, which enables JKPC-4-700 a specific capacity of 465 F g−1 (at 1.0 A g−1 in 6 M KOH). The symmetric capacitors based on JKPC-4-700 deliver an excellent energy density of 117 Wh kg−1 (at a power-density of 900 W kg−1). Our research offers a new strategy for developing high-energy-density, low-cost, and functional carbon materials for efficient EES systems.

Ice template induced assembly strategy for preparation of 3D porous carbon frameworks from low-cost carbon quantum dots for high-performance lithium-ion batteries

Consider the natural similarities between the structures of coal tar pitch and carbon quantum dots (CQDs), the mass-production of low-cost zero-dimensional (0D) CQDs was achieved by using the mild oxidation with hydrogen peroxide (H2O2). The as-obtained CQDs possesses a uniformly distributed size with a diameter of 4.16 ± 0.46 nm, many oxygen-containing functional groups, distinct crystallinity nature and a production yield of ∼18 wt%. Subsequently, ice-template induced assembly coupled with carbonization strategy reveals a transition from 0D CQDs to 3D porous carbon frameworks. Differing from the well-defined porous carbon, the obtained porous carbon frameworks consist of cross-linked and twisted nanosheets, achieving a well-developed hierarchical porous structure with a reasonable specific surface area and a gradient distribution of meso/micropores. LIBs based on porous carbon frameworks as anode materials show excellent long-cycle performance, as evidenced by reversible capacity of up to 273 mAh·g−1 after 1000 charge-discharge cycles at 2000 mA·g−1. The research emphasizes a green method of preparing CQDs from representative low-value coal tar pitch and the directional transition from 0D CQDs to 3D porous carbon frameworks, providing a promising idea to prepare functional carbon materials and endow them opportunities for LIBs anode.

Two-Dimensional Atomically Dispersed Co–N/C Oxygen Reaction Electrocatalysts via Molten-Salt-Assisted Pyrolysis of Metal–Organic Frameworks

Zeolitic imidazolate frameworks (ZIFs) are acknowledged as one of the most perfect precursors to synthesize metal–nitrogen/carbon materials in H2-air and Zn-air fuel cells to boost their cathodic sluggish oxygen reactions. However, abundant atomically dispersed metal–nitrogen sites are useless because of being buried in the derived carbon nanoparticles. Here, a molten-salt-assisted pyrolysis strategy is proposed to prepare two-dimensional porous metal–nitrogen/carbon materials with an attempt to expose metal–nitrogen sites, which involves thermal intercalation/exfoliation and space-confined pyrolysis of layer-structured ZIFs from the molten-salt mixture of KCl/LiCl. Specifically, atomically dispersed Co–N/C porous nanosheets were prepared, showing a high special surface area of 1100 m2 g–1 to host abundant exposed Co–Nx sites. When the Co–N/C electrocatalyst was assembled into a liquid-state Zn-air fuel cell, its peak power density and specific capacity reached up to 239.7 mW cm–2 and 784.9 mAh g–1, respectively, and excellent discharge–charge cycling stability was demonstrated. Furthermore, a Co–N/C-based solid-state Zn-air fuel cell was fabricated, also showing outstanding cell performance, such as a peak power density of 147.2 mW cm–2. This work provides a feasible method to synthesize porous two-dimensional functional carbon materials for electrocatalysis and energy devices.

Synthesis of nitrogen-doped hierarchically porous carbons with ordered mesopores from liquefied wood: Pore architecture manipulation by NH4Cl for improved electrochemical performance

Functional porous carbon materials have attracted significant attentions due to their unique characteristics. Herein, the synthesis of N-doped hierarchically porous carbon (N-HPC) with ordered mesopores from liquefied wood is reported through a soft-templating and chemical blowing method with the assistance of NH4Cl to regulate their pore architectures. The NH4Cl strengthens the interactions between the carbon sources and soft templates in the hydrothermal process to produce carbon materials with highly ordered mesostructure after carbonization. Then, the obtained carbon is ground with NH4Cl, where NH4Cl releases NH3 and HCl upon heating to introduce N atoms and micropores into the carbon structures. Highly ordered p6mm mesostructure, high specific surface area (1160 m2 g−1) and nitrogen content of 3.75 wt% are obtained with the assistance of NH4Cl, which together affords them enhanced electrochemical performance for supercapacitors. The obtained N-HPC electrode displays a specific capacitance of 282 F g−1 at 1 A g−1 and good rate capability.

Bio‐Sourced Zeolite‐Templated Carbons for the Development of Efficient ORR Catalysts

AbstractBio‐sourced Zeolite‐Templated Carbons (ZTCs) were achieved through the use of glycerol as carbon source. A systematic study of the textural and chemical properties is presented on ZTCs achieved at synthesis temperatures between 300 °C and 800 °C. Textural properties are importantly impacted through increasing synthesis temperature. ZTCs featuring high textural quality were synthesized at temperatures as low as 400 °C. Oxygen content was further found to be importantly impacted by the synthesis temperature. This latter plays a crucial role when materials are functionalized with thiourea, as high oxygen content allows for maximizing the incorporation of N and S in the ZTC. Functionalized bio‐sourced ZTCs allowed for achieving unparalleled ORR activities and hydroxyl selectivities when compared to other functionalized carbon materials such as graphene‐based catalysts.

Novel halogen-free deep eutectic solvents for efficient extraction of phenolic compounds from real coal tar

The separation of phenolic compounds from coal tar is conducive to the manufacture of high value-added phenolic products and the further processing of oil. Herein, three novel halogen-free choline dihydrogen citrate (CDC)-alcohols deep eutectic solvents (DESs) were prepared to extract phenolic compounds from real coal tar. The effects of the critical parameters including components and constituent mole ratio of DESs, mass ratio of DESs to coal tar, temperature, and time on extraction efficiency were systematically investigated. It was demonstrated that the extraction efficiency decreased with the extension of alkyl chain of alcohols. Hence, CDC-ethylene glycol (EG) was selected as the appropriate extractant, and the extraction efficiency reached 89.3% under the optimal conditions. Fourier transform infrared spectra revealed that the hydrogen bond interaction between CDC and EG was the main reason for their formation of DES. Phenolic compounds also had hydrogen bond interactions with DES, which was the main driving force for the separation of phenolic compounds from coal tar by DES. Differential scanning calorimeter results displayed that the CDC-EG had no definite melting point, and its glass transition temperature was significantly lower than the melting point of individual components. The CDC was recovered by using ethyl acetate as the back extraction agent. Moreover, to avoid back extraction operation, phenolic resin gel was prepared by one-pot method, which was expected to be suitable candidate as the precursor for functional carbon materials.

Study on gas sensitivity of ZnO@NiO loaded functional carbon materials

We carefully design and prepare a kind of functional carbon material AHC (acetylenic acid - hexamethylene diamine - carbon) using alkynyl acid and cyclohexadiene as raw materials, which load on ZnO@NiO to prepare acetone gas sensor. Studies show that the most appropriate amount of AHC on ZnO@NiO is 0.12% and the best working temperature is 200°C. By comparison, ZnO@NiO@AHC sensor for 100 ppm acetone gas has a maximum response value of 49.08, which is twice as high as of ZnO@NiO sensor. The minimum detection limit is 1 ppm. There is an approximate linear relationship between the concentration and the sensitivity in the range of 1–300 ppm.

Effect of hydrochar on antibiotic-resistance genes and relevant mechanisms during chicken manure composting

The reduction of enhanced antibiotic resistance genes (ARGs) in compost is important to mitigate the risk of ARG transmission in agricultural production. Hydrochar is used in many applications as a functional carbon material with adsorption and catalytic properties. This study investigated the effects of hydrochar addition on bacterial communities, mobile genetic elements (MGEs), and ARGs in chicken manure composting. The addition of 2%, 5%, and 10% hydrochar (dry weight) reduced the total numbers of target ARGs and MGEs in the compost products by 40.13–55.33% and 23.63–37.23%, respectively. Hydrochar changed the succession of the bacterial population during composting, lowering the abundance of potential pathogens and promoting microbial activity in amino acid and carbohydrate metabolism. A significant possible microbial host for ARGs was found to be Firmicutes. Hydrochar was found to affect the host microorganisms and MGEs directly by altering environmental factors that indirectly impacted the ARG profiles, as shown by partial least squares pathway modeling analysis. In conclusion, the addition of hydrochar to compost is a simple and effective method to promote the removal of ARGs.

Acid assisted-hydrothermal carbonization of solid waste from essential oils industry: Optimization using I-optimal experimental design and removal dye application

Solid waste (SW) generated from extracting of essential oils from medicinal and aromatic plants (MAPs) is an abundant and renewable resource, but proper recycling is necessary to prevent negative environmental impacts from improper disposal. This study focused on converting SW from essential oil (EO) extraction industry by citric acid-catalyzed hydrothermal carbonization (c-HTC) coupled with chemical activation into a carbonaceous material to remove organic pollutants. For this purpose, an I-optimal design coupled with response surface methodology (RSM) was developed to investigate the relationship between the severity factor (SF) of the c-HTC process and citric acid dose (HTCcat) on carbon retention rate (CRR) and hydrochar mass yield (MY). Under optimal conditions (5.32 and 2 g for SF and HTCcat, respectively), an optimized hydrochar (HCop) was characterized by a CRR and MY of 71.02% and 56.14%, respectively. HCop was chemically activated by KOH solution (AHCop) and characterized by a specific surface area of 989.81 m2.g−1, a pore volume of 0.583 cm3.g−1, a higher heating value (HHV) of 37.3 MJ/Kg, oxygenated surface functions such as –OH, –COOH, C-O and a methylene blue (MB) removal rate of 90.71%. In addition, modelling of the adsorption isotherms found that the Freundlich isotherm better describes the experimental data, and the second-order model regulates the adsorption kinetics well. Furthermore, The maximum adsorption capacity of AHCop was 588.24 mg.g−1, with a separation factor of 0.625 under the operating conditions (t = 6 h, T = 25 °C, m(AHCop) = 0.2 g, [MB]0 = 300 mg.L-1, and pH = 7), indicating its potential for effectively removing organic pollutants. Together, these results provide crucial information on using c-HTC to convert waste biomass into functional carbon materials to remove organic pollutants efficiently. Therefore, several studies must be conducted out to discover other application fields of this material.

Functional Carbon from Nature: Biomass-Derived Carbon Materials and the Recent Progress of Their Applications.

Biomass is considered as a promising source to fabricate functional carbon materials for its sustainability, low cost, and high carbon content. Biomass-derived-carbon materials (BCMs) have been a thriving research field. Novel structures, diverse synthesis methods, and versatile applications of BCMs have been reported. However, there has been no recent review of the numerous studies of different aspects of BCMs-related research. Therefore, this paper presents a comprehensive review that summarizes the progress of BCMs related research. Herein, typical types of biomass used to prepare BCMs are introduced. Variable structures of BCMs are summarized as the performance and properties of BCMs are closely related to their structures. Representative synthesis strategies, including both their merits and drawbacks are reviewed comprehensively. Moreover, the influence of synthetic conditions on the structure of as-prepared carbon products is discussed, providing important information for the rational design of the fabrication process of BCMs. Recent progress in versatile applications of BCMs based on their morphologies and physicochemical properties is reported. Finally, the remaining challenges of BCMs, are highlighted. Overall, this review provides a valuable overview of current knowledge and recent progress of BCMs, and it outlines directions for future research development of BCMs.

Amino group functionalized pitch-based carbocatalyst for the Henry reaction of furfural

BackgroundTo transform the commodity wastes into high performance materials such as catalyst supports can facilitate the circular economy. Therefore, pitch-based carbon (MPC) which is mainly regarded as a premium carbon byproduct from the petroleum refinery was used to synthesize the supported amino catalyst for the Henry reaction of furfural. MethodsThe amino functionalized pitch-based carbon was prepared by the facile chemical nitration and reduction. The surface textures of the functionalized carbon materials were carefully scrutinized by various characterization techniques, including PXRD, XPS, FT-IR, 13C SSNMR, and Raman spectroscopy. Meanwhile, the amount of surface accessible amino groups was quantified by the colorimetric method using 2-iminothiolane hydrochloride (ITL) as molecular probe. Significant findingThe results reveal that the surface amino groups were immobilized and quantified as 0.391 mmol/g at the periphery of MPC. Moreover, this amino functionalized carbon denoted NRE-MPC could catalyze the Henry reaction of furfural with nitromethane in isopropanol at 90 °C for 6 h to yield 2-(2-nitrovinyl)furan (NVF) as the major product in 65% with 87% furfural conversion. NRE-MPC can be also easily recycled at least four times and the peripheral amino groups alongside the graphitic domains of MPC were still chemically active with perceptible reactivity reduction.

Transforming bio-oil into nitrogen-doped hierarchical porous carbons: Excellent oxygen reduction electrocatalysts for Zn-air batteries

Nitrogen-doped hierarchical porous carbons are considered as important substitutes for noble metal electrocatalysts for the oxygen reduction reaction (ORR) in green-energy devices. Herein, bio-oil, the liquid product of biomass pyrolysis, and urea were used as the carbon and nitrogen source based on a simple MgO template approach. The obtained carbons exhibited a micro-/meso-/macroporous structure, considerable specific surface area and abundance of Graphitic and Pyridinic nitrogen species, leading to the excellent ORR catalytic performance with a half-wave potential of 0.84 V. The assembled primary Zn-air battery displayed a maximum power density of 239.36 mW cm−2 and consistent discharging stability. This work verified the great potential of bio-oil as a sustainable and low-cost precursor of advanced functional carbon materials and was conducive to the large-scale production of efficient carbon-based ORR catalysts.

Imidazole linker‐induced covalent triazine framework–ZIF hybrids for confined hollow carbon super‐heterostructures toward a long‐life supercapacitor

AbstractCarbon super‐heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks (CTFs) and zeolitic imidazolic frameworks (ZIFs) are scarcely explored because of CTF's ordered structure and toxic superacid that dissolves or destabilizes the metal nodes. To solve this problem, herein, we report a straightforward two‐step pathway for the covalent hybridization of disordered CTF (d–CTF)–ZIF composites via preincorporation of an imidazole (IM) linker into ordered CTFs, followed by the imidazole‐site‐specific covalent growth of ZIFs. Direct carbonization of these synthesized d–CTF−IM−ZIF hybrids results in unique hollow carbon super‐heterostructures with ultrahigh nitrogen content (>18.6%), high specific surface area (1663 m2 g−1), and beneficial trace metal (Co/Zn NPs) contents for promoting the redox pseudocapacitance. As proof of concept, the obtained carbon super‐heterostructure (Co–Zn–NCSNH–800) is used as a positive electrode in an asymmetric supercapacitor, demonstrating a remarkable energy density of 61 Wh kg−1 and extraordinary cyclic stability of 97% retention after 30,000 cycles at the cell level. Our presynthetic modifications of CTF and their covalent hybridization with ZIF crystals pave the way toward new design strategies for synthesizing functional porous carbon materials for promising energy applications.

Recent Progress in Nanostructured Functional Materials and Their Applications II

Microstructure of the materials is essential to design new functional materials, especially from atomic scale to micron order structures. Many attempts have been carried out to give nanostructures and such structures have been analyzed using cutting-edge methods both theoretically and experimentally. In this report, recent trends in research on functional materials related to the micro-structures in nano-meter scale are reviewed by mainly introducing the contents of the special issue published in Materials Transactions, vol. 61, No. 8, in which following 6 categories of the topics are included; computational materials science, magnetic materials, advanced functional oxides, carbon and organic materials, and optical materials.

Oxygen-enriched hierarchical porous carbons derived from lignite for high-performance supercapacitors

Functional coal-based carbon materials with reasonable pore structure and surface properties have attracted extensive attention for use in high-performance supercapacitors. Herein, a ball milling-assisted bimetallic salt catalytic pyrolysis strategy was developed to prepare oxygen-doped hierarchical porous carbon (OHPC) derived from lignite. The optimized OHPC-1 shows a large specific surface area (1638 m2/g), rational pore structure distribution (mesopores account for 71.3%), and suitable oxygen doping, which ensure sufficient charge storage, rapid electrolyte ions diffusion, as well as the contributed pseudocapacitance. The obtained OHPC-1 exhibits a high specific capacitance of 283 F/g at 0.5 A/g in 6.0 M KOH electrolyte (operating voltage 1.2 V). The assembled OHPC-1//OHPC-1 symmetrical capacitor delivers a high energy density of 16.5 Wh/kg at the power density of 300 W/kg with long cycling stability. In sum, the proposed facile route for high-value utilization of lignite looks promising for the preparation of cost-effective porous carbons for high-performance supercapacitors.

Immobilization of Platinum Nanoparticles on Covalent Organic Framework‐Derived Carbon for Oxygen Reduction Catalysis

Platinum (Pt)‐based catalysts are considered as the most active catalysts for the oxygen reduction reaction (ORR). However, their applications have remained limited because of the high cost of Pt, and developing catalysts with low Pt contents is a challenge. Herein, a highly active catalyst (Pt–COF800) is constructed for the ORR by immobilizing hierarchical Pt subnano‐ and nanoparticles on covalent organic framework (COF)‐derived carbon. The catalyst shows excellent activity in alkaline conditions. The physical characterization demonstrates low nuclear Pt atoms and nanoparticles and confirms the role of heterogeneous active sites. This work paves the way for the construction of functional porous carbon materials with dual‐scale Pt clusters and may be applied to industrial catalytic reactions.

Improved biological compatibility of carbon materials via aqua regia and CaCl2 treatments

In order to improve the bioactivity of three single-phase carbon materials (resin, pyrocarbon and graphite), chemical modification with aqua regia and CaCl2 solution was used to modify their original surfaces. The bioactivity of materials before and after modification was evaluated by in vitro apatite formation in simulated body fluids (SBF). The results showed that –COOH and Ca2+ were introduced on the sample surface by the chemical modification. The treated resin demonstrated the strongest ability to form a uniform and dense HAP coating after soaking in SBF for its largest specific surface area and the highest content of -COO-. The bone-like apatite coating demonstrated remarkably enhanced in vitro biocompatibility as indicated in the mouse fibroblast (L929) direct contact and ultrastructure observation. The transformation process of hydroxyapatite morphology in functional carbon materials, and the hydroxyapatite formation mechanism were systematically analyzed.

Formation Mechanisms of Hydroxyl-Rich Carbon Layers on Carbon Nanotube Surfaces for Promoting the Hydrolysis of Cellulose to Sugar

Through analysis of the transformation of carbon sources including glucose, fructose, and 5-hydroxymethylfurfural in hydrothermal carbonization (HTC) and the adsorption of carbon tubes (CNTs) with them, the formation mechanism of a hydroxyl-rich carbon layer on the CNT surface is clearly revealed. During HTC, the adsorption of furan and aromatic clusters and even primary particles by CNTs by π–π interaction is noticed as the key condition to improve the utilization rate of carbon sources and the quality of the carbon layer. The coated CNTs own a hydroxyl-rich carbon layer with a thickness of several nanometers on its surface, which provides the ability for functional applications. With the use of the hydroxyl-rich carbon layer-coated CNTs, a low-acid aqueous system is established for the hydrolysis of cellulose to sugar. Accordingly, the cellulose conversion and glucose yield are obviously improved. The route of HTC for hydroxylation of CNTs not only fundamentally avoids the use of strong acid oxidation in traditional method but also provides the useful guidance to prepare functional carbon materials with application prospects.