Claims:1. A 3D bio-activated carbon nanosheet (100) comprising:
pyrolysed tamarind fruit shells (TFSs) or potassium hydroxide (KOH) treated TFSs.
2. Supercapacitor comprising the carbon nanosheet (100) of claim 1, as active material for electrodes.
3. The supercapacitor as claimed in claim 2, wherein the specific capacitance of the supercapacitor comprising bio-activated carbon nanosheet (ACNS) as active material is in a range of 76 to 78 F/g at 1A/g.
4. The supercapacitor as claimed in claim 2, wherein the specific capacitance of the supercapacitor with KOH treated bio-activated carbon nanosheet (K-ACNS) is 245 to 246 F/g at 1A/g.
5. A method of preparing 3D bio-activated carbon nanosheets comprising:
placing a first ceramic dish (201) comprising tamarind fruit shells (TFSs) powder (207) or a second ceramic dish (203) comprising KOH treated TFSs dried powder (209) or both in a tubular furnace (205) comprising a first zone (210), a second zone (220) and a third zone (230), wherein the first dish (210) or the second dish (203) or both are placed at the second zone (220); and
pyrolysing the powders (207, 209) at a temperature range 750oC to 850oC for a predetermined time in the presence of Argon gas (211).
6. The method as claimed in claim 5, wherein the predetermined time is in the range of 2 to 3 hours.
7. The method as claimed in claim 5, wherein the flow rate of Argon gas is 100sccm. , Description:A METHOD OF PREPARING 3D BIO-ACTIVATED PORES CARBON NANOSHEETS FROM TAMARIND FRUIT SHELLS

CROSS-REFERENCES TO RELATED APPLICATION
None.
FIELD OF THE INVENTION
The disclosure generally relates to carbon nanosheets, and in particular to 3D pores activated carbon nanosheets prepared from tamarind fruit shell.
DESCRIPTION OF THE RELATED ART
Carbonaceous materials include carbon elements and different types of allotropes of carbon. Activated carbon (AC) describes a category of amorphous carbonaceous material that possesses high porosity, large internal surface area, and high degree of porosity, good thermal stability and electrical conductivity. Generally, various carbonaceous allotropes based materials are known to exist as AC, amorphous (coal) carbon, activated charcoal, graphite and diamond. AC can be represented as the material with a crystalline structure that represents activated charcoal. In recent years, research is focused on AC preparation from natural bio-resources such as agricultural potential bio-waste material, which is less abundant and easily available. The development of bio-derived carbons are employed with various applications for interesting fields of electrochemical devices like supercapacitor , batteries , electrode fuel cell water purification and treatment applications.
In recent years, several researches have been focused on the synthesis of different biomass precursors for chemical and pyrolysis process. Activated carbon was produced which results in different morphologies with a highly micro/mesoporous nature, which is in favor of promising applications for energy storage. Some more interesting other natural bio-mass products are orange peel, rice straws and rice husk. They possess hierarchical microstructure with micro-pores nature and are applied to Li-ion storage supercapacitor.
Renewable energy sources and energy storage from natural bio-waste or bio derived materials which are converted into valuable products are porous active for a particularly highly porous micro-porous nature supported for highly ionic storage. Mostly, carbon-based nanomaterials are already known for well-familiar nanomaterials such as carbon nanotubes (CNTs), reduced graphene oxide (RGO), mesoporous carbon, carbide-derived carbons, carbon nanoparticles, carbon quantum dots (CQD) and activated carbon from natural bio-waste resources. In particular, bio-mass activated carbon is highly desirable part of future energy storage devices for supercapacitor applications compared to other carbon materials, such as activated carbons.
Materials and methods are disclosed that may overcome the drawbacks of the method discussed earlier.
SUMMARY OF THE INVENTION
In various embodiments a 3D bio-activated carbon nanosheet comprising pyrolysed tamarind fruit shells (TFSs) or potassium hydroxide (KOH) treated TFSs is disclosed. In some embodiments a supercapacitor incorporating the carbon nanosheet as active material for electrodes is described. In one embodiment the specific capacitance of the supercapacitor with bio-activated carbon nanosheet (ACNS) as active material is in a range of 76 to 78 F/g at 1A/g. In another embodiment the specific capacitance of the supercapacitor with KOH treated bio-activated carbon nanosheet (KCNS) is 245 to 246 F/g at 1A/g.
In various embodiments a method of preparing 3D bio-activated carbon nanosheets is disclosed. The method includes placing a first ceramic dish having tamarind fruit shells (TFSs) powder or a second ceramic dish having KOH treated TFSs dried powder or both in a tubular furnace. The furnace includes a first zone, a second zone and a third zone. In various embodiments the first dish or the second dish or both are placed at the second zone. In various embodiments the powders are pyrolized at a temperature range 750oC to 850oC for a predetermined time in the presence of Argon gas. In some embodiments the predetermined time is in the range of 2 to 3 hours. In various embodiments the flow rate of Argon gas is 100sccm.
This and other aspects are described herein.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention has other advantages and features, which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates a 3D bio-activated carbon nanosheet.
FIG. 2 illustrates the method of synthesizing the 3D bio-activated carbon nanosheet.
FIG. 3 illustrates a schematic representation of experimental set-up and their related photographs..
FIG. 4A illustrates the SEM image of TFS after pyrolysis of pure ACNS at a magnification of 10µm.
FIG. 4B illustrates the SEM image of TFS after pyrolysis of pure ACNS at a magnification of 5µm.
FIG. 4C illustrates the SEM image of TFS after pyrolysis of pure ACNS at a magnification of 5µm.
FIG. 4D illustrates the SEM image of TFS after pyrolysis of pure ACNS at a magnification of 5µm.
FIG. 4E illustrates the SEM image of TFS after pyrolysis of pure ACNS at a magnification of 2µm.
FIG. 4F illustrates the SEM image of TFS after pyrolysis of pure ACNS at a magnification of 1µm.
FIG. 4G illustrates the SEM image of TFS after pyrolysis of KOH treated TFSs after pyrolysis KACNS at a magnification of 5µm.
FIG. 4H illustrates the SEM image of TFS after pyrolysis of KOH treated TFSs after pyrolysis KACNS at a magnification of 2µm.
FIG. 4I illustrates the SEM image of TFS after pyrolysis of KOH treated TFSs after pyrolysis KACNS at a magnification of 2µm.
FIG. 4J illustrates the SEM image of TFS after pyrolysis of KOH treated TFSs after pyrolysis KACNS at a magnification of 2µm.
FIG. 4K illustrates the SEM image of TFS after pyrolysis of KOH treated TFSs after pyrolysis KACNS at a magnification of 2µm.
FIG. 4L illustrates the SEM image of TFS after pyrolysis of KOH treated TFSs after pyrolysis KACNS at a magnification of 2µm.
FIG. 5 shows the Raman spectra of ACNSs and KACNSs.
FIG. 6 shows the FT-IR spectra of ACNSs and KACNSs.
FIG. 7 illustrates the Photoluminescent spectra of ACNSs and K-ACNSs and UV-Visible absorption.
FIG. 8A illustrates the CV curves of ACNSs at 10 to 100 mV/s in 3M KOH aqueous 250 solution.
FIG. 8B shows the comparison data of bare electrode Ni-foam with same scan rate 100 mV/s electrochemical capacitive behavior of CNRs cyclic voltammetry curve of as prepared electrodes with ACNSs as active material.
FIG. 8C illustrates the CV curves of KACNSs at 10 to 100 mV/s in 3M KOH aqueous 250 solution.
FIG. 8D shows the comparison data of bare electrode Ni-foam with same scan rate 100 mV/s electrochemical capacitive behavior of CNRs cyclic voltammetry curve of as prepared electrodes with KACNSs as active material.
FIG. 9 illustrates the Comparison data of electrochemical impedance spectroscopy of Nyquist Plot of 3M KOH electrolyte at 1Hz to 100 kHz.
FIG. 10 illustrates the Galvanostatic charge/discharge curve of ACNSs at 1- 8 A/g in 3M KOH aqueous electrolyte solution with potential window (-0.4 to -1).
FIG. 11 illustrates the Galvanostatic charge/discharge curve of K-ACNSs at 1- 8 A/g in 3M KOH aqueous electrolyte solution with potential window (-1 to 0.15 V).
Referring to the drawings, like numbers indicate like parts throughout the views.

DETAILED DESCRIPTION OF THE EMBODIMENTS
While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.
Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of “a”, “an”, and “the” include plural references. The meaning of “in” includes “in” and “on.” Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.
The present subject matter relates to 3D bio-activated pores carbon nanosheets made of tamarind fruit shells (TFSs) or activated TFSs. A supercapacitor having the carbon nanosheet as active material is disclosed. Further a chemical vapour deposition (CVD) method of preparing the 3D bio-activated carbon nanosheets is disclosed.
In various embodiments the invention is a 3D bio-activated pores carbon nanosheet 100 as illustrated in FIG. 1. In one embodiment the nanosheet includes pyrolysed tamarind fruit shells (TFSs). The TFSs are 100% pure. In another embodiment the nanosheets include activated TFSs. The TFSs are activated or treated with potassium hydroxide (KOH).
In various embodiments a supercapacitor having the 3D bio-activated carbon nanosheet is disclosed. In one embodiment the active material in the supercapacitor is bio-activated carbon nanosheet (ACNS). The specific capacitance of the supercapacitor with ACNS as active material is in a range of 76 to 78 F/g at 1A/g. In another embodiment the active material in the supercapacitor is KOH treated bio-activated carbon nanosheet (K-ACNS). The specific capacitance of the supercapacitor with K-ACNS as active material is in a range of 245 to 246 F/g at 1A/g.
The subject matter disclosed includes a method 200 of preparing the 3D bio-activated carbon nanosheets. The method involves chemical vapour deposition (CVD) in a tubular furnace 205. The setup for the preparation is as illustrated in FIG. 2. The tubular furnace 205 has a first zone 210, a second zone 220 and a third zone 230. The second zone 220 lies between the first zone 210 and the third 230 zone and in a mid-region of the tubular furnace 205. In one embodiment a first ceramic dish 201 having tamarind fruit shells (TFSs) powder 207 is placed in the second zone 220 of the tubular furnace 205. The TFSs powder 207 in the first ceramic dish 201 is pyrolised in the temperature range 750oC to 850oC for a predetermined time. In various embodiments the predetermined time is 2 to 3 hours, in the presence of Ar gas in the tubular furnace 205. The TFSs powder 201 that is subjected to pyrolysis in the first ceramic dish 201 yields bio-activated carbon nanosheet (ACNS).
In another embodiment a second ceramic dish 203 having KOH treated TFSs dried powder is placed in the second zone 220 of the tubular furnace 205. The KOH treated TFSs powder in the second ceramic dish 203 is subjected to pyrolysis in the temperature range 750oC to 850oC for a predetermined time. In various embodiments the predetermined time is 2 to 3 hours, in the presence of Ar gas in the tubular furnace. The KOH treated TFSs powder 209 that was subjected to pyrolysis in the second ceramic dish 203 yields KOH treated bio-activated carbon nanosheet (K-ACNS).
In various embodiments the first ceramic dish 201 having tamarind fruit shells (TFSs) powder 201 and the second ceramic dish 203 having KOH treated TFSs dried powder is placed in the second zone 220 of the tubular furnace 205. In various embodiments the TFSs powder is blended with KOH aqueous solution in the ratio 1:5. In various embodiments the powders in the ceramic dishes are subjected to pyrolysis at a temperature range 750oC to 850oC for a predetermined time. In various embodiments the predetermined time is 2 to 3 hours. The carrier gas in the tubular furnace is Argon gas 211. In various embodiments the flow rate of Argon gas is 100sccm. In various embodiments subjecting the precursor TFSs powder 207 in the first ceramic dish 201 and the precursor KOH treated TFSs 209 in the second ceramic dish 203 yields bio-activated carbon nanosheet (ACNS) and KOH treated bio-activated carbon nanosheet (K-ACNS) respectively.
The bio-derived carbon of graphitic carbon nanosheets exhibits good conductivity with high porosity and surface area and are suitable for energy storage supercapacitor applications.
Examples
Example. 1: Experimental setup and synthesis of 3D bioactivated porous carbon nanosheets by CVD.
Materials and method: Tamarind sample collection: The raw material (precursor), tamarind fruit shells (TFSs) was collected from south India (Tamarind tree). Firstly, TFSs were separated from the tamarind fruits and large size tamarind shells were broken into the medium-sized sample. And then, thoroughly cleaned with deionized (DI) water, and subsequently dried in oven-dried at 100°C for around 6h, dried medium size TFSs particles were ground to small size particles using homemade mixer. TFSs samples power weight was around 6gram. The TFSs powders were divided into two parts (1) The activation/pyrolysis/carbonization process for TFSs pure level and (2) The second system half sample for KOH chemical activation.
Chemical activation with potassium hydroxide (KOH): TFSs powder was treated first to chemical activation. In detail, 3g TFSs was blended with 3M KOH aqueous solution (1:5; TFSs:KOH). As prepared KOH mixture was immersed, added continuous and stirred at mixture gel-like solution appearance with a reddish-brown color. Further, the TFSs-KOH samples were filtered and dried at 100°C for 12h. Additionally, TFSs-KOH product was dark brown colored sample which further investigates pyrolysis by (CVD) tubular furnace.
Preparation of active carbon materials: As experimental sections, the ground pure TFSs powder and chemically (KOH) treated TFSs dried powder was further thermally treated like pyrolysis process. The experimental set-up with the detailed explanation as shown in FIG. 3 using three-zone chemical vapor deposition (CVD) tubular furnace with inert Argon (Ar) atmosphere was explored. We approached the experimental part into two types of samples 1) Pure TFSs and 2) KOH-TFSs placed into the ceramic boat with TFSs and TFSs-KOH powders at the center of the furnace quartz tubular inside the horizontal tube CVD furnace into the center zone. The parameters for carbonization/pyrolysis temperature was set at 800°C for 2h 30 min time, hold time at 5°C/min beneath Ar gas flow rates of 100 sccm. After that, reaction was completed and cooled. Additionally, two powder products were washed initially with diluted hydrochloric acid (HCl) to remove any impurities like amorphous carbon and subsequently de-ionized (DI) water to around pH=7. In this study, after carbonization/ pyrolysis by CVD method sample was designated as a name like activated carbon nanosheets (ACNS) and KOH with activated carbon nanosheets (ACNS) as like (K129 ACNS), comparison samples labeled for results and discussions sections.
Materials characterization: As prepared TFSs carbon-based activated carbon nanosheets such as ACNSs and KACNSs were explored for structural and morphological conformation. The porous 3D carbon sheet was observed by scanning electron microscope (SEM), with EDAX (Quanta FEG-250). The micro-RAMAN spectroscopy explored the structural and graphitic evaluated with 530 nm laser excitation (Ar+ laser source) with sample focused and spectrum recorded ranges from 4000 cm−1 to 400 cm−1. Carbon-based functional groups carried by employing FT-IR was conducted on Bruker (E-55) model and also the Photo Luminescence study was carried out.
Electrochemical measurement: The prepared ACNSs and K-ACNSs electrode was studied with a three-electrode configuration system. The electrochemical analyses were performed via Bio-Logic SP-150 model. The electrode active materials were ACNSs and K-ACNSs as working electrodes using etched conducting nickel foam (Ni) substrate, with addition of mixed conductive carbon black and Poly(vinylidene fluoride) corresponded to composition of weight ratio 80:10:10. The above was arranged as slurry in N-Methylpyrrolidone (NMP) and as prepared slurry coated onto nickel foam was dried at 100°C at 5h. The pasted nickel foam (ACNSs and K-ACNSs) was acted as working electrodes, the Ag/AgCl with KCl electrode as reference and platinum (Pt) wire as counter in 3M KOH aqueous electrolytic solution. The optimized potential ranges from 0.15 to - 1V and -0.4 to -1 corresponded to the ACNSs and K-ACNSs products respectively. Furthermore, activated carbon nanomaterials electrochemical activity was recorded in a negative potential window due to their low potential region. Cyclic voltammetry (CV) was observed at 10 to 100 mV/s and GCD investigation at 1 to 10 A/g for different potential of 0.15 to -1 V and -0.4 to -1. The EIS was carried out at ac potential amplitude with 10 mV from 1 Hz to 100 kHz.
Results and discussion: SEM – Morphological studies: A SEM study was explored to reveal microstructural morphological features of ACNSs and K-ACNSs. FIG. 4A-FIG. 4F as shown in prepared carbonization/pyrolysis processes revealed morphological features of ACNSs. The after KOH treated and carbonization of activated carbon nanosheets are called as K-ACNSs. In particular, FIG. 4A showed the multilayer staked like graphite sheet-like microstructure morphology with low magnifications. The arrow marks in FIG. 4B & FIG. 4C focus pure activated carbon sheets. FIG. 4D-FIG. 4F showed the clear view of horizontal and vertical-like sheet morphology of ACNSs 8 sheets, nanosheets thickness ranges from 18.57 to 21.24 nm. Part of the surface morphological features concluded that the multilayer carbon sheets staked overlapping structure are not porous. Small and large particles micro-structures are viewed in different magnifications of 10-1 µm. The major part of the samples are chemically treated with KOH and thermally activated like pyrolysis/carbonization effects of 3D–porous carbon nanosheets. Lower magnification micro-structural images as shown in FIG. 4G and 4H show sponge-like 3D-porous fully inter-connected network combined with graphene-like carbon nanosheets forming an interconnected porous network. As explored in FIG. 4I, every pore of the network have narrow distributed sizes in the scale of sub-micrometer. FIG. 4I possess pore walls with simply a few thin layers of carbon nanosheets. FIG. 4J&4K show morphological structure of pores walls thickness and the diameter of the pores ranges from 46.08 to 62.24 nm. The lower magnification images revealed the foldable and bendable nature with few-layer nanosheets morphology from tamarind fruits shells (TFSs).
Micro-RAMAN- analysis: Raman spectroscopy is widely used sensitive technique for analyzing carbon-based carbon nanostructured materials, which produce typical Raman peaks/bands for various forms of carbon (CNTs, carbon sheets, rods). Generally, very common of the Raman bands of crystalline forms of carbon are graphitic band G-band and crystalline defects means doping or small disorder present in the different carbon domains as defective band D-band. The Raman D-band and G-band corresponded to 1342.70 and 1589.96 cm-1 for the pure ACNSs as shown in FIG. 5. Consequently, the Raman shift value of D-band and G-band corresponded to 1336.50 cm-1 and 1577.57 cm-1 for the K-ACNSs materials as shown in FIG. 5. The crystalline graphitic ratio of the materials 11 consist of the most intense broad band’s showed ID/IG ratio of observed ACNSs and K-ACNSs which correspond to 1.04 and 1.25 respectively. This indicates that K-ACNSs product was observed at a good graphitic ratio. Raman spectroscopy of K-ACNSs confirmed graphitization and presence of 2D broad band at 2808 cm-1 for porous carbon nanosheets confirmation. Moreover, 2D materials with 3D micropores to an increase electron transfer on carbon nanomaterial makes the material convincing for supercapacitor applications.
FT-IR analysis: As seen in FIG. 6, FT-IR spectrum is explored to recognize functional groups in both ACNSs and K-ACNSs samples. Pure ACNSs explained a strong 3436 cm-1 was attributable to COH group’s vibrations with hydroxyl (OH) stretching. 2921 cm-1 was assigned to C-H stretching vibrations. The major 1644 cm-1 were examined in favor of C=C stretching vibration for Sp2 carbon hybridized. The carboxyl functional group was representing C-O starching at 1099 cm-1. The major important samples of K-ACNSs explored well observed broad peaks at 3444 and 2928 cm-1 for C-OH stretching vibrations, very fewer board peaks of OH stretching when compared to ACNSs due to the HCl washing and purified the K-ACNSs sample. The main peak assigned one main transmittance band which was visible, centered at 1636 cm-1 explored C=C stretching vibration for sp2 carbon hybridized functional groups. After the CVD pyrolysis process, most oxygen-containing groups in the composites have been removed to evaluate from the FT-IR curves. It has been reduced into carbon nanosheets through CVD tubular furnace carbonization/ pyrolysis treatment.
PL analysis: PL analysis was explored at room temperature via different excitation wavelengths of 340 – 600 nm for carbon-based materials. The Tamarind fruits shell (TFSs) into valuable materials like activated carbon nanostructures sheets was dissolved in hexane and observed at 361.6, 376.8, 493.9, 505.9, 521.3 and 594.5 nm as shown in FIG. 7. These sharp and broad emission spectra of K-ACNSs was due to their electron-hole combination impact. 521 nm for K-ACNSs was observed. As synthesized 800ºC crystalline K-CNSs explored an effective PL spectrum, carbon forms sp3 and sp2 hybrid orbital. ACNSs was observed at 361.03 nm and 520.61 nm. The small carbon emission peaks as evident from PL spectra were observed at 520.61 nm. Therefore, the complexity of the relationship is pure and KOH treated K-ACNSs explained the mechanism of the observed photoluminescence spectra.
Electrochemical – Supercapacitor applications: For ACNSs and K-ACNSs active material, the electrochemical energy storage for supercapacitor three-electrode applications explored the cyclic voltammetry (CV) carried out in 6M KOH aqueous solution with optimized electrochemical window from -0.4 to -1V and -1 to 0.15 V corresponds to ACNSs and K-ACNSs materials. As exposed in FIG. 8A, purely rectangular curves are seen for pure ACNSs active electrodes at negative region from - 0.4 to -1 mV/s. It clearly indicates a typical electrical double layer behavior (EDLC) and good electrochemical scan rate performance.
FIG. 8B showed comparative statements of pure Ni-foam bare electrode evaluation at -0.4 to -1V potential with applied same scan rate at 100 mV/s. The CV curves comparison of integral area for the ACNSs electrode must be largest among three electrodes, demonstrating the improved electrochemical performance due to the TFSs converted into graphite-like carbon nanosheets. In addition, Cyclic Voltammetry (CV) was carried out for KOH activated carbonized/ pyrolysis of K-ACNSs samples optimized at potential ranges of -1 to 0.15 V and their applied scan rates of 10 - 100 mV/s. In FIG. 8C, The K-ACNSs showed the CV is nearly rectangular confirming EDLC behavior nature and slightly redox activities because of washing/purifications with diluted HCl as shown in FIG. 8D. The comparison data of bare Ni-foam electrode and K-ACNSs indicate an improved CV curve that is attributed to good EDLC capacitance as well as wide area of the integrated surface.
Electrochemical impedance spectroscopy (EIS) was conceded into further evaluations of the electrochemical impedance performances of these ACNS and K-ACNSs materials as shown in FIG. 9. The low-frequency region of the Nyquist plot was performed by conducting AC potential amplitude 10 mV/s, impedance from 100 kHz to 1 Hz. FIG. 10 explained the Nyquist plots of ACNSs and K-ACNSs active electrodes in 3M KOH aqueous solution. In the high-frequency region, it is observed that the semi-circle region of K-ACNSs is the smallest charge transfer resistance (Rct) among the three electrodes. The Rct value observed real axis (Z’) was estimated to be 5.03 Ω and 0.65 Ω corresponding to the ACNSs and K-ACNSs electrodes, respectively. The observed results revealed that a small charge transfer resistance (Rct) was observed in the K-ACNSs electrode when compared to pure ACNSs electrode. Moreover, the nearly 90° leaning line was clearly observed with almost good capacitive behavior. The ending of semi circle part to lower frequency region with Warburg impedance diffusion (WEIS) electrodes has been indicating an ideal good capacitive behavior for ACNSs and K-ACNSs electrodes. Overall, the conclusion from the EIS spectra, KOH activated ACNSs sample is having very low Rct value and then good capacitive behavior to further investigate the galvanostatic charge-discharge.
Galvanostatic charge-discharge: To further study galvanostatic charge-discharge for as prepared products ACNSs and K-ACNSs, the applied current densities ranging from 1 - 8A/g were carried out for ACNSs and K-ACNSs active materials electrodes. The GCD performance of ACNSs materials shows constant current rate with charge-discharge potential window from -0.4 to -1V and the K-ACNSs active materials electrode window ranges from -1 to 0.15 V. The specific capacitance value calculated by using GCD was carried out in a supercapacitor three-electrode system. The specific capacitance (Csp) was calculated using the equation C_sp=(I×Δt)/(m×ΔV) for ACNSs active materials with potential window region from -0.4 to -1V with different current density values of 1, 2, 4, 6 and 8 A/g. The corresponding specific-capacitance (Csp) values were 77 F/g, 63.32 F/g, 50.98 F/g, 49.05 F/g and 46.82 F/g as shown in FIG. 10. The specific-capacitance values for the K-ACNSs with potential window region from -0.4 to -1V with different current density values of 1, 2, 4, 6 and 8 A/g are 245.03 F/g, 177.70 F/g, 119.47 F/g, 106.82 F/g and 89.11 297 F/g as shown in FIG. 11.
Note that, the K-ACNSs overall performance of GCD achieved here is much better than the ACNSs Csp value. The highest specific-capacitance values achieved for both active materials ACNSs and K-ACNSs correspond to the 245.03 F/g and 77 F/g respectively, at 1 A/g. Instead of pure ACNSs the K-ACNSs have much improved twice than that of the electrochemical performance than pure ACNSs. Hence, we confirmed good capacitive storage materials, where the K-ACNSs materials have a larger internal and external surface area and more pores support than that of pure ACNSs. Although there is a high Csp value reported by tamarind fruits shells (TFSs) with KOH chemical activations followed by thermally activated CVD-tubular furnace 800 ºC, that active sample makes a highly porous 3D network interconnected carbon nanosheets. Additionally, the K-ACNSs electrode showed a very good capacitance and ionic storage performance in micro-pores which helps to improve energy storage applications.
Although the detailed description contains many specifics, these should not be construed as limiting the scope of the invention but merely as illustrating different examples and aspects of the invention. It should be appreciated that the scope of the invention includes other embodiments not discussed herein. Various other modifications, changes and variations which will be apparent to those skilled in the art may be made in the arrangement, operation and details of the system and method of the present invention disclosed herein without departing from the spirit and scope of the invention as described here.