Two-step Carbonization Research Articles

Sonication-assisted Activation of Empty Fruit Bunches to Produce Activated Carbon for Supercapacitor’s Electrodes: Surface Chemistry and Morphology Characterization.

Thermochemical treatment of empty fruit bunches (EFBs) had been proven to be the fastest way of converting this agro-industrial waste into value. Two-step carbonization and activation was used to convert the EFB to activated carbon with high specific surface area (SSA) and porosity. Hydrothermal carbonization was done at 225 to 275 ; at retention time of 1 to 3 h. Activation was done at 800 for 1 h, using KOH at two different concentrations. The BET surface area, porosity and surface functional groups of the activated carbon were investigated. The samples experienced change in colourations, with the degree of colouration increases with the time and temperature of the reaction. The increase in these parameters also led to increase in the alkane functional groups and corresponding decreased in the hydroxyl functional groups. The specific surface area was measured using BET and maximum surface of 1375.26 m2/g was obtained when the biomass was carbonized at 275 for 1 h, and activated at 800 using KOH at a concentration of 1:1 to the hydrochar. Ultrasonic post-treatment of the activated carbon enhanced the BET surface area and pore volume to about 1.13 and 1.16 times, respectively. The corresponding pore diameter and volume at this optimum condition were 3.32 nm and 0.73 cm3/g, respectively. The material demonstrated a high specific surface area for electronic and ionic diffusions.

Tailoring closed pore structure in phenolic resin derived hard carbon enables excellent sodium ion storage

The existed plenty of oxygen-containing species in phenolic resin easily inhibit the migration and rearrangement of carbon atoms during pyrolysis, which disfavors the formation of pseudo-graphite structure with larger lateral length (La) and hence leads to poor closed pores, accounting for a low capacity and initial Coulombic efficiency (ICE). Herein, hard carbon with rich closed pores and the most suitable pore size and volume is constructed via a two-step carbonization strategy. It is found that the pre-annealing step can effectively decrease oxygen content by changing the interconnection form of molecule chains, which promotes the growth of La during post-carbonization process, accelerating the formation of closed pores. Besides, with decreasing oxygen content, closed pore size gradually increases, while closed pore number and volume both first increase and then decrease, unveiling that an excessive high and too low oxygen content are unfavorable for the formation of ideal closed pores, resulting from an unsuitable La size. Therefore, the resulting sample, featured by the optimal balance between closed pore number, size (2.52 nm), and volume (0.215 cm3 g−1), delivers a high capacity of 351 mAh g−1 along with an excellent ICE of 83 %.

Regulation of surface oxygen functional groups in starch-derived hard carbon via pre-oxidation: A strategy for enhanced sodium storage performance

During the process of sodium storage in hard carbon anodes, the significance of surface oxygen functional groups cannot be overlooked. In this work, we utilize starch as raw material to synthesize hard carbon by the process of pre-oxidation and two-step carbonization. XPS analysis reveals that pre-oxidation bolsters the presence of CO bonds, thereby providing more active sites. TEM analysis reveals that hard carbon with pseudo-graphite and graphite-like structure is obtained at relatively high carbonization temperature (1400 °C), and the formation of closed pores results in lower specific surface area. The introduction of appropriate oxygen-containing groups in pre-oxidation process can facilitate the cross-linking of starch chains, promoting the increase of defect sites and the sodium storage performance of hard carbon. A series of samples are prepared at various pre-oxidation temperature. Among them, P200-HC obtained after pre-oxidation at 200 °C and carbonization at 1400 °C exhibits the highest reversible specific capacity of 342.7 mAh g−1 at current density of 0.1 C with an initial Coulombic efficiency of 71.1 %, and capacity retention of 87.3 % at current density of 1 C. The work presents a viable approach for the synthesis of hard carbon derived from starch, thereby expanding the design tactic of sodium-ion batteries with improved performance.

Utilization of macadamia nutshell-derived activated carbon for enhanced congo red adsorption

This study addresses the challenge of removing Congo red (CR) from aqueous solutions using activated carbon (AC) derived from macadamia nutshells (MNS). A unique two-step carbonization and pyrolysis process was employed to produce MNS-AC with high surface area and porosity. Key experimental variables, including initial CR concentration, contact time, and pH, were systematically varied in batch mode. Results indicated that the modified AC achieved significantly higher removal percentages compared to unmodified charcoal. At pH 2.0 and an initial dye concentration of 50 mg L−1, CR removal reached 97.48 % for MNS-AC3. The maximum adsorption capacity (qmax) of 58.29 mg g−1 was observed at an initial dye concentration of 200 mg L−1. The pseudo-second-order kinetic model closely matched the experimental data, and equilibrium data analysis using Langmuir and Dubinin-Radushkevich (D-R) isotherm models provided excellent fits. This research demonstrates the potential of using industrial biomass waste to develop sustainable solutions for dye removal in wastewater treatment.

Study on strength and reduction characteristics of iron ore powder-green carbon composite briquettes

The metallurgical industry is a key sector for carbon emissions, and in recent years, there has been widespread attention on the use of biomass resources as a green, renewable, and carbon–neutral energy source material for low carbon ironmaking processes. The waste wood after hydrothermal-pyrolysis carbonization has the characteristics of low content of harmful elements and high content of fixed carbon. In this study, the waste wood after hydrothermal-pyrolysis two-step carbonization treatment was used as a reducing agent for the reduction of iron ore to prepare iron ore powder- green carbon composite briquettes (ICCB) with two carbon–oxygen ratios. The study investigated the effects of reduction behavior and reaction temperature on the reduction performance of the ICCB. The results indicate that with the increase in reaction temperature, the volume of the ICCB gradually contracts, leading to a reduction in mass. The shrinkage rate of the ICCB during self-reduction at 1200℃ is significantly higher than during co-reduction, and the shrinkage effect of the C/O 0.5 ICCB is more pronounced than that of the C/O 0.8 ICCB. Due to the excessive carbon content in the C/O 0.8 ICCB, the carbon cannot be fully consumed during the reaction process, resulting in consistently low compressive strength of the ICCB, with a compressive strength of 12 N after reduction at 1200℃. In contrast, the iron phase in the C/O 0.5 ICCB gradually recrystallizes during the reduction process, ultimately yielding plastic iron briquettes with compressive strengths exceeding 3000 N after different reaction behaviors at 1200℃. In summary, reducing the carbon-to-oxygen ratio and increasing the reaction temperature contribute to the volume contraction and enhanced compressive strength of the ICCB during the reduction process.

Alleviated volume changes of germanium anode via facile chemical confinement strategy

Germanium (Ge) anode shows great promise in overcoming unsatisfied capacity and dendrite formation concerns facing conventional graphite anodes in next generation lithium ion batteries. However, volume changes during repeated alloying and de-alloying cycles seriously impair structural stability and cycle lifespan. In this work, a facile chemical confinement strategy has been firstly proposed to alleviate volume changes of Ge anode. Benefited from strong binding interaction between Ge and ZnS, discrete Ge nanoparticle can be successfully encapsulated within thin protective ZnS shell and N-doped carbon layer (Ge-ZnS@N-C) after two-step carbonization and sulfurization of polydopamine-coating Zn2GeO4 nanorod precursors. In contrast, bulk Ge aggregates and hollow N-doped carbon nanotubes can be formed without chemical confinement of ZnS. The as-prepared Ge-ZnS@N-C sample displays multifold structural merits, including nanosized Ge particles with highly electrochemical activity, sufficient pores and functional groups that facilitate ion diffusion. Besides, protective ZnS shell and N-doped carbon layer can suppress volume changes of Ge nanoparticles and guarantee high electrode reversibility, demonstrated by a series of in-situ and ex-situ experiments. The as-synthesized Ge-ZnS@N-C anodes exhibit stable long-cycle performance (1389.7 mAh/g after 450 cycles at a current density of 0.5 A/g) and excellent rate performance (548.5 and 397.8 mAh/g at 5.0 and 8.0 A/g, respectively).

Carbon Nanosheet Preparation By Low-Temperature Two-Step Carbonization: A Study of Their Properties and Mechanism of Adsorption of Oxidized H2S.

Straw, as a kind of biomass waste, has the advantages of low cost and abundant storage, which makes it a promising renewable resource. Using rice straw as a carbon source, carbon nanosheets were prepared by a two-step carbonization method combining low-temperature pyrolysis and low-temperature hydrothermal, and they were used as H2S removal agents. The results showed that during the two-step carbonization process, the adsorption performance of carbon nanosheets for H2S showed a tendency of enhancing and then weakening with the increase of pyrolysis temperature in the first step, and the sulfur capacity could reach 3.1 mg/g at the maximum of the pyrolysis temperature of 200 °C, which was superior to or close to that of the modified or activated carbon. The XPS, EPR, and CO2-TPD tests showed that the surface of carbon nanosheets was alkaline, containing a large number of hydroxyl groups and the presence of phenoxy persistent free radicals or semiquinone persistent free radicals. It was analyzed that the direct or indirect oxidation of H2S by the persistent radicals under an alkaline environment could convert the -2-valent sulfur into -1-, 0- and +6-valent sulfur to realize the adsorption and removal of H2S. This work, while offering the possibility of utilizing carbon nanosheets made from straw as a material for H2S adsorption and removal, also expands the application of straw waste in exhaust gas treatment.

Designing a cost-effective policy mix for transition toward net-zero emissions: a case study of the mid-term plan by 2035 of Taiwan

This study explores the design of a cost-effective climate policy mix for transition toward net-zero emissions in the mid-term (by 2035). Its novelty lies in the methodological advancements through the development of a soft-linking procedure that integrates a top-down computable general equilibrium model with a bottom-up energy system model. The integrated assessment focuses on the climate policy mix under the framework of Taiwan’s Climate Change Response Act passed in 2023. The analysis shows that a policy mix combining investments in energy transition with user-pay hybrid pricing measures can facilitate cost-effective mitigation and enhance public acceptance. The proposed hybrid pricing includes cost-based electricity pricing and a two-step carbon pricing strategy that encourages early action (before 2030) for larger emitters. Finally, we demonstrate that accelerating the transition is crucial, as it reduces the economic costs of meeting emission targets by inducing further investments in energy efficiency improvement and lowering the carbon pricing levels required to close the abatement gap.

A sustainable and economical solution for CO2 capture with biobased carbon materials derived from palm kernel shells.

This study investigates the synthesize of activated carbon for carbon dioxide adsorption using palm kernel shell (PKS), a by-product of oil palm industry. The adsorbent synthesis involved a simple two-step carbonization method. Firstly, PKS was activated with potassium oxide (KOH), followed by functionalization with magnesium oxide (MgO). Surface analysis revealed that KOH activated PKS has resulted in a high specific surface area of 1086 m2/g compared to untreated PKS (435 m2/g). However, impregnation of MgO resulted in the reduction of surface area due to blockage of pores by MgO. Thermogravimetric analysis (TGA) demonstrated that PKS-based adsorbents exhibited minimal weight loss of less than 30% up to 500 °C, indicating their suitability for high-temperature applications. CO2 adsorption experiments revealed that PKS-AC-MgO has achieved a higher adsorption capacity of 155.35 mg/g compared to PKS-AC (149.63 mg/g) at 25 °C and 5 bars. The adsorption behaviour of PKS-AC-MgO was well fitted by both the Sips and Langmuir isotherms, suggesting a combination of both heterogeneous and homogeneous adsorption and indicating a chemical reaction between MgO and CO2. Thermodynamic analysis indicated a spontaneous and thermodynamically favourable process for CO2 capture by PKS-AC-MgO, with negative change in enthalpy (- 0.21 kJ/mol), positive change in entropy (2.44 kJ/mol), and negative change in Gibbs free energy (- 729.61 J/mol, - 790.79 J/mol, and - 851.98 J/mol) across tested temperature. Economic assessment revealed that the cost of PKS-AC-MgO is 21% lower than the current market price of commercial activated carbon, indicating its potential for industrial application. Environmental assessment shows a significant reduction in greenhouse gas emissions (381.9 tCO2) through the utilization of PKS-AC-MgO, underscoring its environmental benefits. In summary, the use of activated carbon produced from PKS and functionalised with MgO shows great potential for absorbing CO2. This aligns with the ideas of a circular economy and sustainable development.

N, S co-doped coal-based hard carbon prepared by two-step carbonization and a molten salt template method for sodium storage

Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g-1 at 20 mA g-1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g-1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.

Graphene-containing biocarbon from burlap waste: Property comparison with commercial grade graphene nanoplatelets

In this paper, we report a method for synthesizing high-yield graphene-containing biocarbon from burlap waste through a simple two-step carbonization process. The first step involves feedstock carbonization at 600 °C, followed by ball milling and then graphitization at 1200 °C using KOH. A comparative analysis between the obtained bio-graphene and commercial graphene revealed superior graphene properties of the burlap-based graphene. Notably, this bio-based graphene exhibited exceptional characteristics such as a very high BET surface area in the range of 1021 m²/g, low defect-to-graphene ratio of 0.12 in the Raman spectra, and an overall yield of 19% wt. These findings highlight the potential of burlap waste as a sustainable precursor for high-quality graphene synthesis and its potential for various applications.

Engineering of edge nitrogen dopant in carbon nanosheet framework for fast and stable potassium-ion storage

Amorphous carbons are promising candidates as the anode materials for potassium-ion hybrid capacitors (PIHCs). The insufficient storage sites and inferior diffusion kinetics limit their potassium-ion storage capability. Edge nitrogen and morphology engineering are effective pathways to construct accessible active sites and enhanced diffusion kinetics. However, the organic integration of both pathways in amorphous carbon is still challenging. Herein, a “twice-cooking” strategy, including two-step carbonization processes at 700 °C, is designed to synthesize edge-nitrogen-rich lignin-derived carbon nanosheet framework (EN-LCNF). In the first-step carbonization process, the staged gas releases of CO and CO2 from CaC2O4 decomposition exfoliate the carbon matrix into a carbon nanosheet framework. In the second-step carbonization process, the generated CaO reacts with the cyanamide units of graphitic carbon nitride (g-C3N4) to form an edge-nitrogen-rich framework, which is then integrated into the meso-/macropores of carbon nanosheet framework through sp3-hybridized C–N bonds. EN-LCNF with a high edge-nitrogen level of 7.0 at.% delivers an excellent capacity of 310.3 mAh g−1 at 50 mA g−1, a robust rate capability of 126.4 mAh g−1 at 5000 mA g−1, and long cycle life. The as-assembled PIHCs based on EN-LCNF anode and commercial activated carbon cathode show a high energy density of 110.8 Wh kg−1 at a power density of 100 W kg−1 and excellent capacitance retention of 98.7% after 6000 cycles. This work provides a general strategy for the synthesis of edge-nitrogen-rich lignin-derived carbon materials for advanced potassium-ion storage.Graphical

Study on the use of CO2 to strengthen recycled aggregates and pervious concrete

Recycled aggregates (RA) are crushed materials derived from waste concrete or construction debris that play a crucial role in the recycling of construction waste resources. However, RA's irregular particle shape and surface cement paste adhesions limit its potential in pervious concrete applications. To overcome this limitation, the use of carbonation treatment methods to process RA and produce recycled aggregate pervious concrete (RAPC) was investigated. RA was subjected to a pre-carbonation treatment, followed by the production of RAPC mixtures using three slurry-to-aggregate ratios, carbonation curing, and two-step carbonation strengthening, which enhanced the physical and mechanical properties of the specimens. Then, the measurements including permeability coefficient, connected pore fraction, splitting tensile strength, and CT microstructure analysis were performed. A carbon footprint accounting system from "cradle to gate" was conducted to assess the specimens. Our results highlight that an increase in the slurry-to-aggregate ratio in RAPC mixtures results in enhanced mechanical properties but negatively affects permeability performance. By pre-carbonating RA, we significantly increase the pervious concrete's splitting tensile strength, up to 100%, and maintain the compactability while ensuring permeability performance (maximum 3.91% reduction for specimens with slurry-to-aggregate ratio of 0.3). The carbonation treatment method used in our study has ideal environmental effects, as it theoretically sequesters up to 58.12% of the total carbon emissions produced during the production process.

Two-step carbon storage estimation in urban human settlements using airborne LiDAR and Sentinel-2 data based on machine learning

The quantification of carbon storage (CS) within urban areas has become increasingly crucial for achieving global carbon neutrality. This study proposed a new approach to estimating CS in urban human settlements, building on an existing forestry biomass expansion factor (BEF)-based CS estimation approach, and tested it over Suwon, a city in South Korea. First, a tree canopy cover map was created using high resolution land cover data. The urban tree area ratio was then calculated to estimate the BEF-based CS (Step 1 CS), considering parameters from the national forest inventories. Since urban trees have different growing environments and characteristics than forests, the CS for human settlements (Step 2 CS) was estimated using Step 1 CS as well as structural and spectral information of trees from light detection and ranging (LiDAR) and Sentinel-2 data via machine learning (ML) techniques. The dependent variable of the ML models was the difference between the Step 1 CS and the reference CS, which was calculated using field-measured data and existing allometric equations for urban areas. Using both LiDAR and Sentinel-2 information, the random forest model outperformed the other ML models tested, with an R2 of 0.884, a root mean squared error of 0.432 tC/900 m2, and a lower sampling strategy sensitivity. Feature analysis revealed that incorporating structural and spectral information resulted in a more reliable CS estimation by considering different tree environmental characteristics for each grid cell in the model. This data-driven model utilizes remote sensing and ML and can generate spatially explicit CS maps of large urban areas. It can accurately quantify CS in human settlements and is expected to be easily applicable to other urban green spaces.

A highly pyrrolic-N doped carbon modified SiOx anode for superior lithium storage.

The poor interfacial stability and undesirable cycling performance caused by their dramatic volume change hinder the large-scale commercial application of SiOx materials for high-energy-density lithium-ion batteries. Herein, a simple two-step carbonization process is employed to prepare highly pyrrolic-nitrogen-doped carbon modified SiOx anode materials (SiOx@NC). The designed SiOx@NC materials exhibit high electron conductivity and favorable electrochemical kinetics. As expected, the SiOx@NC electrode delivers a high specific capacity of 1003.46 mA h g-1 after 200 cycles at 500 mA g-1. The NCM622||SiOx@NC full cell also demonstrates excellent cycling stability and rate performance.

Fabrication modulation of lignin-derived carbon nanosphere supported Pd nanoparticle via lignin fractionation for improved catalytic performance in vanillin hydrodeoxygenation

Nano-lignin presents great potential in advanced carbon materials preparation since it integrates the advantages of nanomaterials as well the preferable properties of lignin (e.g. high carbon content and highly aromatic structure). Herein, lignin-derived carbon nanosphere supported Pd catalysts (Pd@LCNS) were prepared via a two-step carbonization of Pd2+ adsorbed lignin nanospheres (LNS) and applied in vanillin hydrodeoxygenation. The effect lignin heterogeneity on the synthesis of Pd@LCNS as well as its catalytic performance was further investigated through the synthesis of Pd@LCNS using three lignin fractions with different molecular weight. The results showed that the three Pd@LCNSs exhibited significant differences in the morphology of both carbon support and Pd nanoparticles. Pd@LCNS-3 prepared from high molecular weight lignin fraction (L-3) presented stable carbon nanosphere support with the smallest particle size (∼150 nm) and the highest Pd loading amount (3.78 %) with the smallest Pd NPs size (∼1.6 nm). Therefore, Pd@LCNS-3 displayed superior catalytic activity for vanillin hydrodeoxygenation (99.34 % of vanillin conversion and 99.47 % of 2-methoxy-4-methylphenol selectivity) at 90 °C without H2. Consequently, this work provides a sustainable strategy to prepare uniformly dispersed lignin-based carbon-supported Pd catalyst using high molecular weight lignin as the feedstock and further demonstrate its superior applicability in the selective transfer hydrogenation of vanillin.

Constructing mesoporous biochar derived from waste carton: Improving multi-site adsorption of dye wastewater and investigating mechanism

The development of cost-efficient biochar adsorbent with a simple preparation method is essential to constructing efficient wastewater treatment system. Here, a low-cost waste carton biochar (WCB) prepared by a simple two-step carbonization was applied in efficiently removing Rhodamine B (RhB) in aqueous environment. The maximum ability of WCB for RhB adsorption was 222 mg/g, 6 and 10 times higher than both of rice straw biochar (RSB) and broadbean shell biochar (BSB), respectively. It was mainly ascribed to the mesopore structure (3.0–20.4 nm) of WCB possessing more spatial sites compared to RSB (2.2 nm) and BSB (2.4 nm) for RhB (1.4 nm✕1.1 nm✕0.6 nm) adsorption. Furthermore, external mass transfer (EMT) controlled mass transfer resistance (MTR) of the RhB sorption process by WCB which was fitted with the Langmuir model well. Meanwhile, the adsorption process was dominated by physisorption through van der Waals forces and π-π interactions. A mixture of three dyes in river water was well removed by using WCB. This work provides a straightforward method of preparing mesoporous biochar derived from waste carton with high-adsorption capacity for dye wastewater treatment.

Covalent-organic framework derived nitrogen-enriched carbon: A remarkable adsorbent to remove 4-nitrophenol from water

Severe industrialization causes adverse impacts on human beings because of the contamination of water with toxic and undegradable organic contaminants such as phenolic compounds (PCs). Here, some nitrogen-rich carbonaceous materials, CDC(x)s, have been first prepared through the two-step carbonization of a covalent-organic framework SNW-1 (Schiff-based network-1). SNW-1 was pyrolyzed; the obtained product and potassium hydroxide mixtures were again pyrolyzed under different temperatures to get CDC(x)s. The carbonaceous materials were characterized and applied in the adsorptive elimination of para-nitrophenol (pNP, one of the representative PCs) from water. One CDC(x) called CDC(800) had a very high maximum adsorption capacity (Qo), 1190 mg/g (at pH 7) which is 6 times that of activated carbon, and higher than that of any other known materials. Based on the adsorption results under various conditions, characteristics of CDC(800), and calculations, the plausible adsorption mechanism, such as hydrogen bonding (mainly between -NO2 of pNP and H on the pyrrolic group of CDC(800)) and π-π interaction, could be suggested. Finally, the remarkable CDC(800) adsorbent was recyclable for several runs with ethanol washing; therefore, can be recommended as a competitive adsorbent to remove pNP from water.

Preparation of spherical porous carbon from lignin-derived phenolic resin and its application in supercapacitor electrodes

Lignin is the most abundant aromatic biomass resource in nature and is the main by-product of paper industry and biorefinery industry, which has the characteristics of abundant source, renewable and low cost. Deep eutectic solvents (DES) are a nascent environmentally friendly solvent option that is gaining traction. DES composed of p-toluenesulfonic acid and choline chloride is used for batch treatment of alkaline lignin, and the bio-oil obtained is ternary polymerized with formaldehyde and phenol to obtain lignin phenolic resin. The porous carbon material is produced through a two-step carbonization process, utilizing phenolic resin derived from lignin as the primary source of carbon. The morphology and composition of the carbon were analyzed by SEM, TEM, XRD, TGA, XPS and Raman spectroscopy, the specific surface area and pore size distribution were analyzed by BET. The results showed that the specific surface area of the lignin-based phenolic resin was significantly higher than that of the pure phenolic resin carbon, and the porous carbon material that was acquired demonstrated a specific surface area of as much as 1026 m2/g. In the three-electrode system, the specific capacitance of DLPFC can reach 245.8 F/g (0.25 A/g), with a very small decrease in the value of specific capacitance at 10,000 cycles, with a retention of 97.62% (10 A/g). The porous carbon demonstrated a specific capacitance of 112.4 F/g at a current density of 0.5 A/g, and the capacitance retention rate could still reach 98.8% after 5000 charge/discharge cycles, with high cycling stability (in the two-electrode system). The prepared symmetrical supercapacitors exhibited high energy density and power density of 3.9 Wh/kg and 125.0 W/kg. The results suggest a new idea of high value-added application of lignin phenolic resin for high-performance supercapacitor electrodes.

Boosting supercapacitor performance through the facile synthesis of boron and nitrogen co-doped resin-derived carbon electrode material

In this study, we present the synthesis of porous carbon materials designated as B, N co-doped porous carbon materials (PRNB), co-doped with boron and nitrogen through a two-step carbonization process of self-made phenolic resin. Among them, urea, boric acid, and potassium oxalate were used as the heteroatom dopants and activator, respectively. The co-doping of boron and nitrogen induced a unique electronic structure, resulting in improved capacitance performance compared to single-doped materials. Moreover, the addition of potassium oxalate as an activator facilitated the etching of the carbon framework during pyrolysis. Owing to the co-doping effect of boron and nitrogen and the abundant micropores, the PRNB material exhibited a remarkably high specific capacitance of 330 F g−1 at 1 A g−1. It also displayed excellent rate performance (70 %) and stability, with only a 6 % loss after 10,000 cycles compared to other materials. The symmetric electrode based on PRNB achieved an energy density of up to 29.7 Wh kg−1 in a neutral electrolyte, which provides a novel approach for resin-derived carbon to improve electrochemical performance.