One-step Activation Research Articles

Carbon fiber with superhydrophilic interface as metal-free air electrode for all-solid-state Zn-air batteries

The burgeoning interest in all-solid-state Zn-air batteries as next-generation power sources for portable electronics is conspicuous. A pivotal aspect of their advancement lies in developing cost-effective, metal-free air electrodes with high-activity bifunctional oxygen electrocatalysts. This study introduces a superhydrophilic carbon fiber modified with oxygen functional groups (CF-O), achieved through a straightforward one-step activation treatment. Comparative analyses reveal that the CF-O electrode surpasses pristine CF in oxygen reduction and evolution reaction (OER and ORR) activity due to enhanced active sites and expedited ion transport. Notably, the OER/ORR performance depends on the type and quantity of oxygen functional groups. The optimal CF-O electrode displays an OER overpotential of 365.6 mV at 10 mA cm-2 and an ORR peak potential of 0.683 V. Utilizing the CF-O sample as the air electrode in all-solid-state Zn-air batteries yields an open-circuit voltage of 1.28 V and a peak volume power density of 82.8 mW cm-3. Furthermore, endurance testing reveals a charge/discharge voltage gap of 1.07 V at a current density of 1.0 mA cm-2 after 30 cycles. This facile and economical fabrication approach for metal-free air electrodes holds promise for advancing high-performance metal-air batteries compared to various existing techniques.

Improvement in capacitive and Zn-storage performance of asphalt-based N, O, and Mo-doped porous carbon by Mo-catalytic oxidative modification

With the escalating demand for electrochemical energy storage, asphalt-based porous carbon is emerging as an outstanding candidate for electrodes, which hold a promising outlook in supercapacitors and zinc storage. However, the π-π stacking and conjugation of highly aromatic PAHs in asphalts significantly influence its reaction with activators, rendering it unfavorable for generating reactive groups and defective sites. Thus, the aromaticity of the asphalts has been restricted by catalytic oxidation of MoO3, and the honeycomb N, O, and Mo-doped porous carbon has been acquired by one-step activation with the help of KBr-K2CO3 molten salt. The representative sample, CAC/Mo, possesses a remarkable hierarchical pore structure and abundant heteroatoms. Mo species produce enough defects in the carbon skeleton due to the effect of stress balance and electron arrangement. Consequently, CAC/Mo sustains a high specific capacitance of 432.9F g−1 in the three-electrode system, a high specific capacity of 225.6 mAh/g, and a high energy density of 180.5 Wh kg−1 in the cathode of zinc ion capacitor (ZIC). Next, the composite CAC/Mo@I also attains a satisfactory specific capacity of 161.6 mAh/g and cycling stability in the cathode of a zinc-iodine battery.

Comparative analysis of EBT dye removal using Spartium junceum and derived activated carbon: experimental and DFT insights

ABSTRACT This study explores the use of Spartium junceum biomass (SJ) to create activated carbon (SJAC) through a one-step activation with phosphoric acid. Characterisation of SJ and SJAC was conducted using FTIR spectroscopy, pHpzc measurement, nitrogen adsorption/desorption isotherms, and SEM to analyse their surface chemical groups, morphology, and texture. Results showed that SJAC has a well-developed mesoporous structure, high pore volume, and a significantly enhanced specific surface area (325.759 m2 g−1) compared to raw SJ (1.647 m2 g−1). The adsorptive performance of SJ and SJAC was tested by removing the anionic dye Eriochrome Black T (EBT). Using central composite design under response surface methodology, batch experiments were optimised for factors like pH, adsorbent dosage, initial EBT concentration, and contact time. Optimal conditions were determined using a desirability function. Adsorption data were analysed with various isothermal models, showing that the Freundlich model best described SJ, while the Langmuir model was more suitable for SJAC. SJAC exhibited an exceptional adsorption capacity of 261.36 mg g−1, about five times higher than SJ. Thermodynamic analysis indicated that the adsorption process for both sorbents was spontaneous and endothermic. Density functional theory was used to investigate the adsorption mechanism of EBT on SJ and SJAC, identifying multiple mechanisms such as electrostatic interactions, pore filling, hydrogen bonding, and π-π stacking, with pore filling being the primary mechanism for SJAC. SJAC maintained over 77% EBT adsorption efficiency across four reuse cycles, highlighting its potential for EBT remediation applications.

Removal of methyl orange dye by high surface area biomass activated carbon prepared from bamboo fibers

To obtain a green biomass-activated carbon with abundant pores for the high-efficiency removal of dye, this study fabricated bamboo fiber-based activated carbons (BFACs) via a one-step activation strategy with the assistance of ZnCl2 as the activator for the removal of methyl orange (MO). The results showed that the specific surface area (SSA) of BFAC-500 activated at 500 ℃ was as high as 2512 m2/g with a total pore volume (Vtotal) of 1.411 cm3/g. The adsorption kinetics and thermodynamics of MO conformed to the pseudo-second-order kinetic model and Langmuir isotherm model, respectively. Based on the Langmuir fitting results, the theoretical maximum adsorption capacity (Qm) of MO adsorbed by BFAC-500 was calculated to be 591.71 mg/g at 318 K, pH=4.5, 0.4 g/L, with an equilibrium time of about 60 min. According to the thermodynamic calculation, the value of ΔH0 was less than 40 kJ/mol, which indicates that the adsorption mechanism was mainly based on physical adsorption, and based on the BET, Zeta potential, FTIR, and XPS before and after the adsorption, it was further known that it was mainly characterized by pore filling, electrostatic adsorption, hydrogen bonding, and π-π interactions. Moreover, when pH < pHzpc, the surface of BFAC-500 was positively charged and the adsorption of Cl-, SO42- and PO43- on MO had little effect; when pH>pHzpc, the surface was negatively charged and the adsorption of BFAC-500 on MO was enhanced by Na+, K+, and Mg2+. The BFAC materials in this study have promising applications in the practical removal of MO dyes.

Boosting 5-Hydroxymethylfurfural Electrooxidation by Porous Biochar via Loading Numerous Surface-Exposed Cobalt Phosphonates.

The electrooxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) demonstrated its unique superiority, not only in reducing overpotential and improving energy conversion efficiency for green hydrogen production but also in utilizing abundant biomass resources and producing high-value-added chemicals. However, designing highly efficient electrocatalysts for HMF electrooxidation (HMF-EOR) with low cost and high performance for large-scale production remained a huge challenge. Herein, we introduced an easy one-step activation process to produce P-doped porous biochar loaded with multiple crystal surfaces exposed to CoP2O6 catalysts (CoP2O6@PC), which exhibited outstanding electrooxidation performance. To achieve a current density of 50 mA cm-2, only a low overpotential of 200 mV was needed for the electrooxidation of HMF in 1.0 M KOH + 10 mM HMF. This performance far surpassed that of other similar materials. CoP2O6@PC exhibited outstanding HMF-EOR performance with high conversion (nearly 100%), selectivity (97.1%), faradaic efficiency (95.3%), and robust stability. This work represents a promising strategy to fabricate macroscale and low-cost HMF-EOR electrocatalysts and achieve potential industrial applications of HMF-EOR.

Effect of pretreatment and activation conditions on pore development of coal-based activated carbon

Abundant pore volume and appropriate pore configuration are two crucial characteristics of high-performance carbonaceous adsorbents and catalysts. In this study, influences of pre-treatments (e.g., breaking, sieving and ash removal by acid) and activation conditions (e.g., activation time) on pore parameters (including BET surface area, pore diameter and pore hierarchy degree) of resultant activated carbon were systematically investigated. In addition, the difference between conventional carbonization-activation (i.e., the two-step preparation method) and one-step activation in pore development of activated carbons was revealed. The sample prepared by a 120-minute one-step activation exhibited a BET surface area high to 1038.1 m2/g and a pore hierarchy at 50.7 %. Based on the kinetics analysis using TGA reactor, reaction between the activator (i.e., CO2) and carbon matrix was found enhanced in one-step activation, contributing to the generation of mesopores. Remarkably, a new indicator, Effective Activation Rate (EAR) was proposed to accurately describe the activation rate in one-step synthesis after decoupling the release of moisture and volatile compounds. The above conclusions provide guidance for flexibly regulating the pore configurations of activated carbons derived from natural precursors.

Surface functionalized biochar for the effective capacitive deionization of lead ions

Biochar has emerged as a promising alternative to activated carbon for capacitive deionization (CDI) due to its special architecture and functionalities. However, the selective purification of trace toxic ions is always limited by the number of specific functionalities. Herein, a thiosemicarbazide-modified biochar (BC-S) was developed for removing trace Pb2+ from water. The cotton stalk derived biochar (BC) is prepared by one-step activation with CO2, which has a high mesoporous ratio and is favorable for ion transport. It was then chemically modified with thiosemicarbazide to add additional Pb2+ adsorption sites. BC as anode and BC-S as cathode formed an asymmetric device for testing, and it exhibited a Pb2+ adsorption capacity of 68.5 mg g−1, much higher than that of the symmetric BC electrode (15.9 mg g−1). More importantly, BC-S still performs excellent Pb2+ selectivity in the presence of various cations such as Ca2+ and Mg2+. The ex-situ XPS and SEM revealed that Pb2+ is adsorbed by −C-S, −C = S, −SOx-, and −N- functional groups on the electrode surface, where electrosorption and chemisorption co-occur. This work shows that biochar can be engineered and explored broadly as an inexpensive sustainable electrode material for the separation and recovery of heavy metals and salt ions from water.

A hierarchical porous structure and nitrogen-doping jointly enhance the lithium-ion storage capacity of biomass-derived carbon materials

Biomass-derived carbon materials are considered potential lithium-ion anode materials because they are sustainable, renewable, economical, and environmentally friendly and have tunable microstructures. However, biomass-derived carbon materials have low specific capacity and show capacity degradation during long-term electrochemical cycling, which prevents their application in high-performance lithium-ion batteries. Hence, in this paper, nitrogen-doped hierarchical porous carbon (NHPC) is synthesized from a biomass waste material, corncob, through one-step activation and carbonization procedures. N-doping in the NHPC modifies the electron distribution on the surface of carbon, resulting in the generation of additional lithium-ion storage sites and enhancing electrode wettability to increase the conductivity. Additionally, the doping procedure results in a hierarchical porous structure with an increased specific surface area and pore volume, which facilitates ion transport and provides remarkable cycling stability. The electrochemical performance of NHPC is improved by the jointly beneficial combination of N-doping and the hierarchical porous structure. The optimized NHPC electrode provides a reversible specific capacity of 700 mAh g−1 after 100 cycles at 100 mA g−1. This study provides a simple and efficient method for improving the electrochemical properties of biomass-derived carbon materials through elemental doping and modulation of microscopic morphology and structure.

Structural Engineering of Carbon Host Derived from Organic Pigment toward Physicochemically Confinement and Efficient Conversion of Polysulfide for Lithium-Sulfur Batteries.

Lithium-Sulfur Batteries (LSBs) have attracted significant attention as promising next-generation energy storage systems. However, the commercial viability of LSBs have been hindered due to lithium polysulfides (LiPSs) shuttle effect, resulting in poor cycling stability and low sulfur utilization. To address this issue, herein, the study prepares a sulfur host consisting of micro/mesopore-enriched activated carbonaceous materials with ultrahigh surface area using organic pigment via facile one-step activation. By varying the proportion of chemical agent, the pore size and volume of the activated carbonaceous materials are manipulated and their capabilities on the mitigation of LiPSs shuttle effect are investigated. Through the electrochemical measurements and spectroscopic analysis, it is verified that structural engineering of carbon hosts plays a pivotal role in effective physical confinement of LiPSs, leading to the mitigation of LiPSs shuttle effect and sulfur utilization. Additionally, nitrogen and oxygen-containing functional groups originated from PR show electrocatalytic activation sites, facilitating LiPSs conversion kinetics. The approach can reveal that rational design of carbon microstructures can improve trapping and suppression of LiPSs and shuttle effect, enhancing electrochemical performance of LSBs.

Thermal behavior analysis and reaction mechanism in the preparation of activated carbon by ZnCl2 activation of bamboo fibers

In this study, bamboo powder (BP), bamboo parenchyma cells (PCs), and bamboo fibers (BFs) were used as precursors to prepare activated carbon by ZnCl2 one-step activation to investigate the differences in the pore structures of the three. The results showed that BFs-based activated carbon had a higher specific surface area (2129 m2/g). Subsequently, the activation reaction paths of the BFs-based activated carbon preparation process were analyzed and explored by TGA, XRD, TG-MS-FTIR, EA, and other analytical methods, and the reaction mechanism was inferred. The results showed that the main reaction below 220 °C was the breaking of molecular bonds of oxygen-containing functional groups on hemicellulose, and the pyrolysis by-products at this stage were dominated by small molecules such as H2O, CO2, CH4, CH3OH, and HCHO. The pyrolysis of cellulose and the activation reaction of ZnCl2 were the main reactions between 220 °C and 650 °C. ZnCl2 was a strong dehydrating agent that can form ZnOCl2·2 H2O with intramolecular water molecules, and gradually decompose to form ZnO with the increase in temperature, the main gaseous products in this temperature interval were mainly H2O, CO, CO2, C3H4, and CH4. Above 650 °C, pyrolysis was basically completed and continued to shift to the aromatic structure, with the gaseous products mainly being H2, H2O, CO2, CH4, CO, C3H4, and a small amount of CH3OH and HCHO.

Comparison of methods for activating sesame stalk lignin biochar for removing benzo[a]pyrene from sesame oil

In this study, three activators and two activation methods were employed to activate sesame lignin-based biochar. The biochar samples were comprehensively characterized, their abilities to adsorb benzo[a]pyrene (BaP) from sesame oil were assessed, and the mechanism was analyzed. The results showed that the biochar obtained by one-step activation was more effective in removing BaP from sesame oil than the biochar produced by two-step activation. Among them, the biochar generated by one-step activation with ZnCl2 as the activator had the largest specific surface area (1068.8776 m3/g), and the richest mesoporous structure (0.7891 m3/g); it removed 90.53 % of BaP from sesame oil. BaP was mainly adsorbed by the mesopores of biochar. Mechanistically, pore-filling, π-π conjugations, hydrogen bonding, and n-π interactions were involved. The adsorption was spontaneous and heat-absorbing. In conclusion, the preparation of sesame lignin biochar using one-step activation with ZnCl2 as the activator was found to be the best for removing BaP from sesame oil. This biochar may be an economical adsorbent for the industrial removal of BaP from sesame oil.

Machine learning application for predicting key properties of activated carbon produced from lignocellulosic biomass waste with chemical activation

The successful application of gradient boosting regression (GBR) in machine learning to forecast surface area, pore volume, and yield in biomass-derived activated carbon (AC) production underscores its potential for enhancing manufacturing processes. The GBR model, collecting 17 independent variables for two-step activation (2-SA) and 14 for one-step activation (1-SA), demonstrates effectiveness across three datasets—1-SA, 2-SA, and a combined dataset. Notably, in 1-SA, the GBR model yields R2 values of 0.76, 0.90, and 0.83 for TPV, yield, and SSA respectively, and records R2 of 0.90 and 0.91 for yield in 2-SA and combined datasets. The model highlights the significance of the soaking procedure alongside activation temperature in shaping AC properties with 1-SA or 2-SA, illustrating machine learning's potential in optimizing AC production processes.

Pore-making strategy of bagasse-based heteroatom-doped porous carbon in chromium adsorbents

To enhance the utility of bagasse and increase its value, this study prepared bagasse-based activated carbon (ACUP) using a novel urea phosphate (UP) activator. The preparation involved a one-step activation and functionalization process under varying impregnation ratios and activation times. The resulting ACUP was characterized, and its specific surface areas and yields were compared between direct and two-step activation methods. The study also examined the impact of adsorption conditions on Cr(VI) removal performance. Findings revealed that the one-step method yielded activated carbon with high adsorption capacity (138.42 mg/g) and removal rate (79.45 %) for Cr(VI). The duration of activation time significantly influenced the adsorption capacity. These ACUP materials show great potential for practical Cr(VI) removal applications.

Antigen Presenting Cell Mimetic Lipid Nanoparticles for Rapid mRNA CAR T Cell Cancer Immunotherapy.

Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable clinical success in the treatment of hematological malignancies. However, producing these bespoke cancer-killing cells is a complicated ex vivo process involving leukapheresis, artificial T cell activation, and CAR construct introduction. The activation step requires the engagement of CD3/TCR and CD28 and is vital for T cell transfection and differentiation. Though antigen-presenting cells (APCs) facilitate activation in vivo, ex vivo activation relies on antibodies against CD3 and CD28 conjugated to magnetic beads. While effective, this artificial activation adds to the complexity of CAR T cell production as the beads must be removed prior to clinical implementation. To overcome this challenge, this work develops activating lipid nanoparticles (aLNPs) that mimic APCs to combine the activation of magnetic beads and the transfection capabilities of LNPs. It is shown that aLNPs enable one-step activation and transfection of primary human T cells with the resulting mRNA CAR T cells reducing tumor burden in a murine xenograft model, validating aLNPs as a promising platform for the rapid production of mRNA CAR T cells.

Effect of Preparation Process on the Physicochemical Properties of Activated Carbon Prepared from Corn Stalks

The preparation of activated carbon (AC) from agricultural and forestry wastes is one of the effective methods for resource utilization. In this study, AC was prepared from corn stalk (CS) by pyrolysis, one-step activation, and two-step activation to determine the optimum preparation method. Based on this, a single-factor design was used to investigate the influence of activating agents (KOH, NaOH, KOH/NaOH), activation temperatures (600, 700, 800 °C), and activation times (60, 90, 120 min) on the physicochemical properties of AC. The physicochemical properties of AC were characterized by Thermal gravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Cyclic voltammetry (CV). The results showed that the AC obtained by the one-step activation method (KOH, 800 °C, 120 min) exhibited a rich pore structure and excellent electrochemical properties (Ipa = 159.8 μA, Ipc = −169.5 μA). However, for the two-step activation method, the AC exhibited a poor pore structure and electrochemical properties (Ipa = 130.8 μA, Ipc = −129.9 μA). In addition, one-step activation provides high-quality AC in a shorter activation time than two-step activation.

Energy utilization of agricultural waste: Machine learning prediction and pyrolysis transformation

The rapid screening of agricultural waste materials for capacitor preparation holds significant importance in comprehending the relationship between material properties and enhancing experimental efficiency. In this study, we developed two machine learning models to predict electrode material characteristics using 2997 data points extracted from 235 articles. The identification and influence of key features on prediction indices provide a theoretical foundation for subsequent practical preparation. Through regression analysis and index evaluation, corn straw emerged as the optimal material for capacitor preparation, leading us to propose a one-step activation and two-step modification approach to convert corn straw into porous biochar. By modifying biochar with Co(NO3)2·6H2O, the maximum electrode capacitance of porous carbon reached 732.6 F/g. Furthermore, the electrode exhibited exceptional cycle stability with a remaining capacitance of 96 % after 5000 cycles. The prepared symmetric capacitor demonstrated pseudocapacitance behavior with a capacitance of 183.15 F/g at a current density of 1.0 A/g, power density of 22 kW/kg, and energy density of 9.03 Wh/kg. Considering the increasing annual output of corn straw and its superior industrial application prospects compared to acid-, base-, or precious metal-based alternatives due to their cost-effectiveness and environmental friendliness, these findings highlight the potential practical value in utilizing modified corn straw biochar as an efficient energy storage electrode material.

Preparation of AC-TiO2 by One-Step Activation Method and the Degradation Properties of Tetracycline Hydrochloride

A one-step activation technique for preparing activated carbon/titanium dioxide (AC-TiO2) photocatalyst was developed in this study, which achieved the expansion of activated carbon and the crystallization transition of titanium dioxide in one step. The properties of the generated materials were examined utilizing photocatalytic degradation of tetracycline hydrochloride (TC). The optimized sample (10%AC-TiO2) has a photocatalytic efficiency of 99.8% in 60 minutes and a degradation efficiency of more than 90% after 5 cycles. According to the experiment results, the combination of AC with TiO2 at high temperatures can induce a considerable number of oxygen vacancies in TiO2, hence increasing the reaction activation site, resulting in improved photocatalytic performance. A strong C-Ti chemical bond can be formed between AC and TiO2. Simultaneously, using AC as the substrate decreases the aggregation problem induced by the small nano size of TiO2 and increases dispersion uniformity. The unique carbon structure with a amount of pore structure can considerably improve the catalystand#39;s adsorption efficacy. Because of the synergistic effect of adsorption-degradation and the perfect photocatalytic activity of TiO2, the composite photocatalyst has exceptional photocatalytic efficiency, opening new possibilities for TiO2 modification.

Ultrafast treatment of stainless steel for efficient and stable water electrolysis

Stainless steel is widely utilized in industrial applications of alkaline water electrolysis due to its high anti-corrosion property, but it usually suffers from low catalytic activity. The complete activation of stainless steel to improve its efficiency while maintaining its excellent corrosion resistance is thus important for lowering the energy consumption of H2 production. Here, we developed an ultrafast one-step activation for stainless steel based on high-temperature heat treatment and quenching in an aqueous solution. After the activation, the resulting Ni-doped stainless-steel mat (Ni-SSM) exhibited significantly improved activity for both the hydrogen evolution reaction and the oxygen evolution reaction in comparison to pristine SSM. When assembled for overall water electrolysis, Ni-SSM delivered a current density of 100 mA/cm2 at a cell voltage of 1.72 V in 1 M KOH at 25 °C, outperforming most of the stainless-steel-based electrodes reported thus far. Under a quasi-industrial environment of 6 M KOH at 60 °C, Ni-SSM displayed extraordinary performance, producing a current density of 500 mA/cm2 at a low cell voltage of 1.615 V. Further durability testing showed that Ni-SSM maintains high performance at a current density of 500 mA/cm2 under this quasi-industrial environment for at least 150 h. Similar activation processes were applied to different substrates to verify the versatility of this strategy, and enhanced performance for alkaline water electrolysis was observed among all the selected substrates. Finally, 5 × 5 cm2 pieces of Ni-SSM were prepared and assembled in an anion exchange membrane (AEM) electrolyzer, in which they delivered a current of 12.5 A at a cell voltage of 1.93 V in 1 M KOH at 65 °C. Therefore, the effectiveness of this activation strategy for improving activity and its feasibility and versatility together suggest its great potential for industrial application.

Nitrogen-doped oxygen-rich porous carbon framework towards aqueous zinc ion hybrid capacitors and zinc-iodine batteries

Zinc ion hybrid capacitors (ZIHCs) and zinc-iodine batteries (ZIBs) have attracted significant attention as promising components for large-scale energy storage owing to their excellent security, environmental friendness and high theoretical capacity of Zn anode. However, there still exist some respective obstacles for commercial applications, such as limited specific capacity, poor cycling stability of ZIHCs or shuttle effect of polyiodide of ZIBs. Here, to enhance electrochemical properties, we report a synergistic one-step activation strategy using KMnO4 and Zn(NO3)2 for nitrogen-doped oxygen-rich three-dimensional hierarchical porous carbon (NOPC). Benefiting from its high specific surface area, three-dimensional porous morphology and improved redox sites from heteroatom doping, the as obtained NOPC exhibits desired electrochemical performance as cathode for ZIHCs and ZIBs. The NOPC-based electrode achieves an ultra-high specific capacity of 230 mAh g−1 at 0.1 A g−1, and 118 mAh g−1 can be maintained at 10 A g−1. Besides, a distinguished energy density of 213.0 Wh kg−1 and a high-power density of 11.2 kW kg−1 are also achieved with a constructed ZIHCs device. Furthermore, the NOPC/I2 composite exhibited excellent rate performance (54 mAh g−1 at 10 A g−1) and cycling performance (∼88.3 % retention upon 5000 cycles) in ZIBs device. This work provides a facile but effective strategy to develop 3D porous electrodes for ZIHCs and ZIBs with remarkable rate and cycling performance.

An Effective Strategy to Synthesize Well-Designed Activated Carbon Derived from Coal-Based Carbon Dots via Oxidation before Activation with a Low KOH Content as Supercapacitor Electrodes.

The development of coal-based activated carbon for supercapacitors provides a robust and effective approach toward the clean and efficient use of coal, and it also offers high-quality and low-cost raw materials for energy storage devices. However, the one-step activation method for preparing coal-based activated carbon has problems, such as difficulty in introducing surface-functional groups and high KOH dosage. In our work, activated carbon was prepared through an effective strategy of oxidation and KOH activation with a low KOH content by employing coal-based carbon dots as raw material. The influence of temperature during the KOH activation of carbon dots on a specific surface area, pore structure, and various quantities and types of surface-functional groups, as well as on the electrochemical performance of supercapacitors, was systematically studied. The as-prepared sample, with the alkali-carbon ratio of 0.75, processes a large specific surface area (1207 m2 g-1) and abundant surface-functional groups, which may provide enormous active sites and high wettability, thus bringing in high specific capacitance and boosted electrochemical performances. The oxygen and nitrogen content of the activated carbon decreases while the carbon content increases, and the activation temperature also increases. The as-prepared activated carbon reaches the highest specific capacitance of 202.2 F g-1 in a 6 M KOH electrolyte at a current density of 10 A g-1. This study provides new insight into the design of high-performance activated carbon and new avenues for the application of coal-based carbon dots.