Activated Carbon Samples Research Articles

Activated Carbon and Biochar Derived from Sargassum sp. Applied in Polyurethane-Based Materials Development.

Activated carbon (AC) and biochar (BC) are porous materials with large surface areas and widely used in environmental and industrial applications. In this study, different types of AC and BC samples were produced from Sargassum sp. by a chemical activation and pyrolysis process and compared to commercial activated carbon samples. All samples were characterized using various techniques to understand their structure and functionalities. The metal content of the samples was characterized by using an inductively coupled optical emission spectrometer (ICP-OES). A toxicity test was applied to investigate the effect of AC/BC on organisms, where Sinapis alba seed and Escherichia coli bacteria-based toxicity tests were used. The results revealed that the samples did not negatively affect these two organisms. Thus, it is safe to use them in various applications. Therefore, the samples were tested as fillers in polyurethane composites and, thus, polyurethane-AC/BC samples were prepared. The amounts of AC/BC mixed into the polyurethane formulation were 1%, 2%, and 3%. Mechanical and acoustic properties of these composites were analyzed, showing that by adding the AC/BC to the system an increase in the compression strength for all the samples was achieved. A similar effect of the AC/BC was noticed in the acoustic measurements, where adding AC/BC enhanced the sound adsorption coefficient (α) for all composite materials.

Electronic synergy between NiCo2O4 and adjacent carbon defects to enhance styrene cracking activity for styrene-saturated activated carbon regeneration

The design and construction of catalysts featuring abundant electron transfer and defect structures for the regeneration of styrene-saturated activated carbon (AC) pose a significant challenge. This paper presents successful preparation of a regenerated adsorbent with synergistic catalytic active sites of NiCo2O4 spinel and carbon defects using a simple impregnation method. Enhanced catalytic activity is attributed to the electronic synergy between NiCo2O4 and carbon defects in 2.5Ni-2.5Co-900, involving substantial electron transfers, abundant acidic sites, and strong reducibility. Reactive oxygen species and the robust oxygen transfer facilitate the deep oxidation of intermediates and carbon elimination. The optimized regenerated adsorbent achieved a styrene adsorption capacity of 446.4mg/g with a recovery of 92.4% of the fresh sample, which is 1.5 times higher than 5Ni-900 and about 1.8 times higher than the unmodified regenerated activated carbon sample, RAC-900. The mechanism of styrene cracking and the evolution of intermediates were investigated using thermogravimetric-infrared coupling, and the effects of catalytic temperature and active sites on styrene cracking, deep oxidation of intermediates, and elimination of carbon deposits were explored. Kinetic analysis demonstrated that the adsorption of styrene on regenerated samples entailed a multifaceted process integrating both physical and chemical adsorption. The significance of chemical adsorption became increasingly evident as the concentration of defective sites grew. Intra-pore diffusion is the main determining step of the adsorption process. After five cycles, the adsorption capacity of 2.5Ni-2.5Co-900 decreased to below 25%, suggesting promising strategies to overcome challenges of regenerating styrene-saturated AC.

Influence of Phosphoric Acid Activation on Physiochemical Characteristics of Activated Carbons and Their Performance as Supercapacitor

ABSTRACTWe investigate the influence of phosphoric acid (H3PO4) activation on physiochemical characteristics of activated carbons (ACs) as a function of number of activation steps such as two‐step and three‐step and impregnation ratio (IR). Scanning electron microscopy observations identified that different morphologies in the forms of graphene sheet‐like, nano‐granular, and flake‐like carbon structure in the cases of ACs. FTIR spectroscopy confirmed that successful incorporation of phosphorous group in the ACs by H3PO4 activation. X‐ray diffraction (XRD) profile exposed that irrespective of the activation method and IR, all AC samples showed narrow and sharp XRD crystalline peak along with the amorphous signals. Raman scattering analysis suggested that three‐step activation create more defective structure as compared to two‐step activation route. Nitrogen adsorption–desorption isotherm measurements indicated that upon fabricating ACs via three‐step and two‐step activation approach, around 6.5 times and 3‐fold enhancement in the value of surface area of ACs as compared to that of carbon before activation. In addition, higher the IR value, lower the textural properties of ACs. This study demonstrated that three‐step activation methodology is capable of generating highly porous AC when compared to two‐step activation route. Cyclic voltammetry analysis showed that for the electrode developed from AC that fabricated via three‐step activation, capacitance retention of 50% is achieved upon tuning the scan rate by 10 times. The same electrode exhibited the capacitance retention of 45% upon increasing the current density by 10 times. We have also compared the electrochemical performance of symmetric and asymmetric supercapacitors. Electrochemical capacitance retention of symmetric and asymmetric supercapacitors is determined to be 100% and 92% respectively after 1000 cycles at the current density of 1 A g−1. Based on the Ragone plot study, it is observed that the maximum energy density of 5 W h kg−1 and the maximum power density of 943 W kg−1 are attained for the case of symmetric supercapacitors. Asymmetric supercapacitor displayed improved energy density of 7.15 W h kg−1 and modest power density of 432 W kg−1.

Facile oxygen-enriched hierarchical porous carbon particles based on biomass wastes for improving the adsorption of malachite green from aqueous solutions

The abundance of active groups and the surface areas of adsorbents used for the removal of contaminants such as dyes are very important for the effective adsorption process. For this purpose, the high surface area-activated carbon was obtained by activation of agricultural waste chestnut shells as carbon precursor(CSAC) with sodium hydroxide in the first stage of this study. In the second stage, the doping of oxygen atoms with nitric acid was carried out to further improve the surface properties of this activated carbon (O-doped CSAC). The obtained oxygen-rich activated carbon sample was used as an adsorbent to remove a cationic dye malachite green (MG). EDS, SEM, XRD, FTIR and nitrogen adsorption analyses were used for the characterisation of these activated carbon samples. FTIR, elemental analysis and EDS analyses showed a significant increase in the amount of oxygen groups on the surface. The BET surface area obtained for CSAC had a high surface area of 1548 m2/g. Kinetic, thermodynamic and isotherm parameters for the adsorption of MG with O-doped CSAC were determined. The qe values obtained for MG adsorption with O-doped CSAC showed an adsorption efficiency of about 90 %. An adsorption capacity of 284.6 mg g-1 was obtained at 298 K with the Langmuir isotherm. The adsorption mechanism of MG with O-doped CSAC was also investigated.

Comprehensive protection against ammonia by Cu2+ modified activated carbon

An innovative “material-component-whole” evaluation model was used to assess the overall protective performance of gas masks against ammonia. Coconut shell-based carbon (AC-S), coconut shell-impregnated carbon (ACCu-S), coal-based carbon (AC-C), and coal-impregnated carbon (ACCu-C) were chosen as the adsorbents for this study. The physicochemical characteristics of the activated carbon samples were analyzed through SEM, BET, FT-IR, EA, XPS and XRD tests. This research delves into the breakthrough curves of ammonia gas by the activated carbon and canisters under varying concentrations of ammonia, ambient temperatures, airflow velocities, and relative humidity, also exploring the breakthrough curves of ammonia gas by gas masks under different ammonia concentrations and airflow patterns while considering both dynamic and static adsorption of activated carbon. The empirical results show that increased levels of ammonia concentration, ambient temperature, and airflow velocities lead to decreased protection duration of activated carbon and canisters. Conversely, an elevation in the relative humidity within the ammonia gas stream results in an expansion of the protection time. This study found a linear correlation between the protection time of S and C canisters and the corresponding protection time of the impregnated carbon. Lastly, the protective time of gas masks in sinusoidal airflow mode is highlighted as having a more significant impact.

Sustainable production of in-situ activated carbon from arecanut husk and their supercapacitor applications

A facile and sustainable method is adopted for the synthesis of activated carbon from arecanut husk biomass. The inherent potassium enrichment in arecanut husk is exploited for an in-situ activation process. The activated samples exhibited an optimal porosity with abundant meso/micro pores and channels making them a promising candidate for supercapacitor applications with a specific capacitance value as high as 217 Fg−1 as calculated from the CV curves. The values for non activated and KOH activated carbon samples derived from arecanut husk were only 60 and 80 % of this value respectively. A fully functional symmetric supercapacitor prototype was also fabricated which exhibited a capacitance value of 46.2 Fg−1 with an energy density of 6.1 Whkg−1 at a power density of 270 Wkg−1.

Catalytic pyrolysis of plastic waste using activated carbon from cotton waste

This study introduces a novel approach to plastic waste management and energy recovery by synthesizing highly porous activated carbon from an often-overlooked resource, waste cotton fabric (WCF), using H3PO4 as an activating agent. The synthesized waste cotton fabric activated carbon samples (WCF-AC) were utilized as a solid acid catalyst in the catalytic pyrolysis of low-density polyethylene (LDPE), with the aim of converting LDPE into fuel-range hydrocarbons. This research highlights the potential of bio-based waste materials in the synthesis of eco-friendly and cost-effective catalysts for feedstock recycling. The impact of the H3PO4 impregnation ratio and the carbonization/activation temperature on the physicochemical properties of the resulting WCF-AC samples was investigated, providing valuable insights into the optimization of activated carbon production. The catalytic activity of the synthesized WCF-AC samples was evaluated, demonstrating a reduction of 12°C in the LDPE degradation temperature. Furthermore, this work revealed a substantial increase in the formation of carbocyclic compounds, with light aromatics such as benzene, toluene, and xylene constituting up to 43 % of the pyrolysis output. In certain instances, a decrease in heavier hydrocarbons beyond C11 was observed, indicating the selective yield of specific range hydrocarbons. This study underscores the potential of bio-based acid catalysts, such as the synthesized activated carbon presented here, in plastic recycling. The approach adopted in this research aligns with the principles of the circular economy, promoting resource efficiency and sustainability.

Highly efficient regeneration of VOCs-saturated activated carbon by vacuum-thermal treatment

The substantial energy consumption and carbon loss associated with conventional thermal regeneration of activated carbon (AC) pose significant constraints on the advancement of deactivated AC recycling. Here, a vacuum-thermal process was applied to regenerate AC saturated with VOCs. Results showed that desorption efficiency under vacuum conditions (99 % at 200 °C) was significantly higher than that in air and nitrogen (85.2 % and 86.4 %, respectively). The adsorption capacities of different AC samples were maintained at 74.2 %, 97.8 %, 90.9 %, and 96.4 % after seven regeneration cycles, respectively. Pore structure analysis showed that vacuum-thermal regeneration caused less damage to the AC pore structure compared to the air and nitrogen. In addition, micropores were shown to be most conducive to the adsorption of VOCs, while mesopores larger than 4 nm are conducive to desorption. The larger the saturated vapor pressure of the VOCs, the larger the driving force it is subjected to, and the easier it is to desorption. Density field theory (DFT) calculations showed that the higher the binding energy between VOCs and AC surface, the more stable the adsorption system, making it more difficult to regenerate the adsorbent. This work provides insight into the development of an economical and environmentally friendly regeneration route for AC adsorption.

Hydrogen adsorption, migration and desorption on amorphous carbon: A DFT and AIMD study

Physisorption is the general dominating adsorption mode on pure carbonaceous materials. In this study, we examined if chemisorbed hydrogen can be accomplished without incorporating metals on carbon surfaces. We constructed two 100-atom amorphous carbon (a-C) models with different microenvironments (42 % 2-fold, 52 % 3-fold, and 6 % 4-fold coordinated carbon atoms and 18 % 2-fold and 82 % 3-fold, respectively) using ab initio molecular dynamics (AIMD) simulations to mimic activated carbon samples in reality. The structural, energetic, electronic structure and kinetic properties of hydrogen adsorption, migration, and desorption on the a-C surfaces were analyzed using density functional theory (DFT) and AIMD calculations, which showed that: (1) hydrogen molecules could spontaneously dissociate on the convex side of 2-fold coordinated carbon atoms. Physisorption of hydrogen molecules mainly took place on 3-fold coordinated carbon atoms. (2) Regarding the multiple hydrogen adsorption, the entire a-C model could uptake around 156 hydrogen atoms with the adsorption energy per hydrogen atom about −0.70 to −0.60 eV at high hydrogen pressure. In addition, we found that the average individual adsorption energy of a single hydrogen atom on different carbon atoms could be used as a quick prediction for the saturated hydrogen adsorption energy. (3) The migration barrier of a hydrogen atom between two adjacent carbon atoms was about 2 eV at both low and high hydrogen coverage, indicating that hydrogen mobility on this designed a-C model was low. The desorption of a hydrogen molecule can take place at 300 K using AIMD calculation, but not for atomic hydrogen desorption. In this work, we demonstrated that hydrogen chemisorption could take place on this designed a-C without the decoration of metal particles to enhance hydrogen adsorption amounts. The materials design to balance hydrogen chemisorption, migration, and desorption shall be considered in the future.

Valorization of argan paste cake waste: Enhanced CO2 adsorption on chemically activated carbon

This study addresses the critical need to reduce energy penalties in CO2 capture processes by exploring the potential of activated carbons derived from argan paste cake for post-combustion CO2 capture applications. Leveraging their cost-effectiveness, stability in humid conditions, and microporous structure, a series of activated carbons with diverse textural characteristics were synthesized through a two-step chemical activation process employing a KOH: biochar ratio of 1:1. Activation temperatures ranged from 700 to 850 °C. Characterization techniques such as Raman spectroscopy, X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, elemental analysis, and Fourier-transform infrared spectroscopy were employed to analyze the structural and chemical properties of the synthesized activated carbons. Remarkably, all synthesized samples exhibited excellent CO2 adsorption properties. Notably, the activated carbon sample prepared at 700 °C (APC-500–700) demonstrated the highest CO2 adsorption capacity, reaching up to 4.89 mmol/g at 0 °C and 2.98 mmol/g at 25 °C. Additional samples, including APC-500–800 and APC-500–850, exhibited CO2 adsorption capacities of 4.89 mmol/g and 4.83 mmol/g, respectively, at 0 °C, with corresponding values of 2.74 mmol/g and 2.60 mmol/g observed at 25 °C. Selectivity and stability tests were conducted to evaluate the adsorption performance under varied conditions, further highlighting the potential of activated carbon derived from argan paste cake in contributing to efficient CO2 capture processes. These findings underscore the significance of synthesis conditions in tailoring adsorption performance and pave the way for the sustainable utilization of waste biomass for environmental applications.

Experimental study of gas adsorption using high-performance activated carbon: Propane adsorption isotherm

Activated carbon is widely used for its diverse adsorptive abilities, with a vast range of current and emerging uses. This study developed a data set for high-performing activated carbon, its adsorption abilities with differing adsorbents, and an understanding of what deviations are present compared to the widely used adsorption models. This study included the construction of Tóth isotherms in varying conditions. Building a strong isotherm correlation is desired, with an understanding of the relationship between the pores of the activated carbon sample, operating parameters, and the adsorbent. The present data could complement efforts in designing adsorbed natural gas storage systems. Experimental data was collected using a Constant Volume Variable Pressure (CVVP) apparatus, consisting of a temperature-regulated vessel containing the activated carbon sample dosed with varying adsorbents through a controlled dosing vessel. Analysis of the derived data gave a well-fitted Tóth adsorption isotherm, giving the maximum specific adsorption capacity of the activated carbon to be 2.28 g of propane per gram of activated carbon with a standard error of regression

Ammonia gas adsorption study using copper impregnated on mesoporous activated carbon from seaweed waste for indoor air purification

Ammonia (NH3), as a toxic gas, has negative impacts on human health even at low concentration, especially in narrowed spaces. In this study, activated carbon was synthesized from seaweed waste and copper was loaded on its surface (Cu/AC filter) to prepare a cost-effective NH3 adsorbent. Pyrolysis (carbonization) temperature can significantly affect the texture properties of activated carbon, and the best activated carbon sample with BET of 1114 m2/g was obtained through pyrolysis at 500 °C followed by KOH-activation at 750 °C. Different from other lignocellulosic biomass-based activated carbons (mainly microporous structure), the prepared algae-based activated carbons mainly have a mesoporous structure (pore size: 7.0–9.0 nm). Copper-impregnation significantly changed the surface chemistry of activated carbon, thereby greatly increasing the NH3 adsorption capacity (max: 128.6 mg/g). The adsorption performance was primarily determined by chemical adsorption (caused by copper impregnation and related inherent functional groups, including O–H, C–H, O–Si–O and SiO–H), followed by physical adsorption (caused by BET). Isotherm studies indicated that NH3 adsorption on Cu/AC filter followed the Langmuir model, whereas the adsorption kinetics followed the pseudo-second-order model. Furthermore, the adsorption mechanism was controlled by intraparticle diffusion model with initial adsorption behavior. This can be attributed to the mesoporous structures of activated carbon, consequently dramatically improving the diffusion efficiency. In addition, the Cu/AC filter showed good regeneration performance, as it can still remain above 90 % after 5 cycles. Finally, this study demonstrated that the seaweed waste is a good precursor for activation carbon and has great potential as excellent NH3 adsorbent for indoor air purification.

Textile effluent treatments using natural adsorbents and vapor absorption technology: A box behnken design approach

The untreated effluents from textile industries pose significant hazards to the environment and human health, exacerbating challenges in effluent disposal management and water scarcity. In response, various methods, particularly adsorption, have been widely employed in chemical and process industries to remove contaminants. This study focuses on converting industrial effluents into potable water using natural adsorption and vapor absorption techniques and optimizing the method with Response Surface Methodology (RSM) analysis using Box-Behnken design (BBD). The optimized condition obtained through RSM was replicated and found to have an adsorption capacity of 45 % after the column and 65 % total removal after the vapor absorption column. Activated carbon samples from textile industries underwent characterization techniques such as FTIR, XRD, TGA, and SEM analyses. Different adsorbing materials including date seeds, tamarind seeds, and palm leaves were utilized for effluent purification. Chemical analyses were conducted on raw effluent, settled effluent, and condensed water and showed that there is a certain metal ion removal. Through this approach, the study aims to provide an eco-friendly and economically viable solution for effluent treatment, addressing both environmental concerns and resource management challenges and a possible coupling of two different approaches into a viable solution.

Experimental Study on the Preparation of Lignin-Based Activated Carbon and the Adsorption Performance for Phenol.

Biomass waste and wastewater are important wastes in the process of industrialization, which need to be effectively treated and utilized. In this work, an innovative method of collaborative treatment of biomass waste and phenol-containing wastewater is proposed. Biomass waste was used to produce activated carbon (AC), and then AC was used for phenol removal in wastewater treatment. Two kinds of typical biomass waste material, namely, coconut shell and lignin, were used. Physical activation (steam activation) and chemical activation methods were compared. Results show that steam activation is an effective method for coconut shell AC production. The largest Brunauer-Emmett-Teller (BET) surface area was 1065 m2/g at 800 °C. Chemical activation could produce AC samples with higher BET specific surface area. The lignin AC with K2CO3 activation has the largest BET surface of 1723.8 m2/g at 800 °C. FTIR results indicated that K2CO3 activation could greatly enhance the formation of surface oxygen-containing functional groups. Both coconut shell AC and lignin AC samples show excellent performance for phenol removal. The highest phenol removal efficiency for coconut shell AC and lignin AC are 96.87% and 98.22%, respectively. Adsorption kinetic analysis show that the pseudo-first-order kinetic model is able to describe the adsorption characteristics of phenol in wastewater treatment. Recycling properties show that regeneration of lignin AC could maintain high adsorption performance for phenol.

Investigation of kinetics and thermodynamics of methylene blue dye adsorption using activated carbon derived from bamboo biomass

This research paper aimed to evaluate the potential of activated carbon (AC) made from non-torrefied and torrefied bamboo biochar samples for the purpose of adsorbing methylene blue solution. The process involved impregnating bamboo biochar with a 5 M potassium hydroxide (KOH) solution at a 1:4 ratio of biochar to KOH, followed by carbonization at 800 °C, 900 °C, and 1000 °C to produce activated carbon samples. The samples were then characterized using techniques such as XRD, FESEM-EDX, FTIR, FE-TEM, and BET analysis to study their respective phase, surface morphology, elemental composition, functional groups, and structural and surface properties. The results showed that the torrefied bamboo AC exhibited a specific surface area of 366 m2/g and a total pore volume of 0.24 m3/g. Kinetic analyses showed adsorption following a pseudo-second-order model, with a capacity of 83.3 mg/g according to the Langmuir model and a favorability constant of 0.52 from the Freundlich model. Thermodynamic studies revealed the process to be spontaneous and endothermic, with changes in enthalpy and entropy of 77,810.73 kJ/mol and 269.9 kJ/mol·K, respectively. These findings highlight the effectiveness of bamboo-derived AC as a sustainable adsorbent for MB dye removal, offering a promising solution for water pollution control.

Preparation and Characterization of Lignin‐Based Activated Carbon by Rubidium Chloride Chemical Method

AbstractIn order to prepare carbon adsorbent materials, lignin was used as raw material and rubidium chloride as activator, activated carbon materials were prepared by chemical activation method, and its structure was characterized and its adsorption performance on methylene blue solution was investigated; the adsorption of crystalline violet dye was carried out at different temperatures, and the adsorption thermodynamics was studied. The results showed that: the specific surface area of the activated carbon was 433.32 m2/g, the pore volume was 0.2191 cm3/g, and the average pore size was 2.0222 nm; the adsorption value of methylene blue could reach 172.0 mg/g, and it could quickly and efficiently adsorb methylene blue solution; the adsorption effect on crystal violet solution was good, and the saturated adsorption amount at 40 °C was up to 279 mg/g, and the removal rate reached 93 %, belonging to the spontaneous adsorption thermodynamic reaction. The experiment proved that rubidium chloride can be used as an activator to activate lignin raw materials to prepare activated carbon samples, and can effectively adsorb dyes.

Effect of Thermal Activation on the Structure and Electrochemical Properties of Carbon Material Obtained from Walnut Shells.

A simple activation method has been used to obtain porous carbon material from walnut shells. The effect of the activation duration at 400 °C in an atmosphere with limited air access on the structural, morphological, and electrochemical properties of the porous carbon material obtained from walnut shells has been studied. Moreover, the structure and morphology of the original and activated carbon samples have been characterized by SAXS, low-temperature adsorption porosimetry, SEM, and Raman spectroscopy. Therefore, the results indicate that increasing the duration of activation at a constant temperature results in a reduction in the thickness values of interplanar spacing (d002) in a range of 0.38-0.36 nm and lateral dimensions of the graphite crystallite from 3.79 to 2.52 nm. It has been demonstrated that thermal activation allows for an approximate doubling of the specific SBET surface area of the original carbon material and contributes to the development of its mesoporous structure, with a relative mesopore content of approximately 75-78% and an average pore diameter of about 5 nm. The fractal dimension of the obtained carbon materials was calculated using the Frenkel-Halsey-Hill method; it shows that its values for thermally activated samples (2.52, 2.69) are significantly higher than for the original sample (2.17). Thus, the porous carbon materials obtained were used to fabricate electrodes for electrochemical capacitors. Electrochemical investigations of these cells in a 6 M KOH aqueous electrolyte were conducted by cyclic voltammetry, galvanostatic charge/discharge, and impedance spectroscopy. Consequently, it was established that the carbon material activated at 400 °C for 2 h exhibits a specific capacity of approximately 110-130 F/g at a discharge current density ranging from 4 to 100 mA/g.

Multifunctional activated carbon derived from novel biomass for high-performance energy storage applications: A sustainable alternative to fossil-fuel-derived carbon

Biomass-derived activated carbon materials have been attracted as low-cost and sustainable electrode materials for energy storage applications. In this work, we synthesised activated carbon from black gram whole skin for the first time, and the used source is a cost-effective carbon precursor. Nitrogen and phosphorous doping in activated carbon improved electronic conductivity, surface area and porosity. In supercapacitor application, the nitrogen and phosphorous doped activated carbon sample showed a high specific capacitance of 425 F g−1 at 0.5 A g−1 and cycling stability of about 92.5 % capacitance retention even after 5000 cycles in a three-electrode system. The observed stable specific capacitance in a three-electrode system encouraged us to make a two-electrode symmetric device, showing a specific capacitance of 100 F g−1 at 0.5 A g−1 with a higher energy density of 20 Wh kg−1. In addition, the lithium storage capability of doped carbon showed good capacity of 750 mAh g−1 at 0.1 A g−1 with a reversible capacity of 687 mAh g−1 after 100 cycles. The hetero-atom doped activated carbon derived from black gram skin showed outstanding electrochemical performance towards supercapacitor and lithium battery application, indicating a potential alternative to fossil fuel-derived carbon.

Stimulating Mesoporous Characteristics of Activated Carbon through Pyrolysis of Compacted Hydroxyethyl Cellulose—A Showcase for H2S Removal

Stimulating Mesoporous Characteristics of Activated Carbon through Pyrolysis of Compacted Hydroxyethyl Cellulose—A Showcase for H2S Removal

Highly efficient peanut shell activated carbon via hydrothermal carbonization and chemical activation for energy storage applications

In this study, the activated carbon samples from peanut shells (PS) are synthesized through hydrothermal carbonization (HTC) with and without activating agents, and their electrochemical properties are studied for supercapacitor applications. The raw precursor (PS) powder is loaded with an activating agent (ZnCl2 or H3PO4 or KOH) during the hydrothermal treatment at 200 °C for 7 h. The treatment with the activating agent facilitates the generation of oxygen-containing functional groups on the precursor surface, enhancing the porosity and electrochemical performance of the sample. Further, the samples are subjected to carbonization at 400 °C for 3 h. The powder XRD patterns show peaks at around 24–26° and 43°, corresponding to the amorphous and graphitic carbon, respectively. The morphological examination reveals more meso and macro pores when treated with the activating agent. Raman spectra manifest the amorphous carbon nature of the samples exhibiting ID and IG bands. The porous carbon treated with H3PO4 shows a specific surface area of 17.8 m2/g and a pore volume of 0.037 cm3g−1. The H3PO4 treated sample shows a high specific capacity (Cs) of 240 F/g at 1 A/g current density, an energy density (E) of 4.08 W h kg−1, and a power density (P) of 101.3 W kg−1. The Retention rate of the sample is approximately 90 % up to 1200 cycles. These types of hybrid supercapacitor materials are suitable for battery-type applications.