Facile synthesis of hierarchical morphology highly porous carbon cobalt oxide composite from one-step carbonization of bio-waste for energy storage application

Facile synthesis of hierarchical morphology highly porous carbon cobalt oxide composite from one-step carbonization of bio-waste for energy storage application | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Facile synthesis of hierarchical morphology highly porous carbon cobalt oxide composite from one-step carbonization of bio-waste for energy storage application Abdullah Ba, Y S Nagaraju, H Ganesha, S Veeresh, D S Suresh, S P Vijaykumar, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5236326/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 14 You are reading this latest preprint version Abstract A new strategy made to have a low-cost highly porous carbon electrode material by using bio-waste date seeds is activated with potassium hydroxide (KOH) for the synthesis of porous carbon cobalt oxide composite (PCCo) by facile one-step carbonization, and achieved high specific capacitance. The characterization of PCCo composite was done by powder X-ray diffraction, Fourier transform infrared spectrometer, field emission scanning electron microscopy, high-resolution transmission microscopy, and Raman spectroscopy techniques to confirm the changes in the chemical formation of the composite. The obtained PCCo composite has a porous structure with carbon frameworks and uniformly dispersed Co 3 O 4 nanoparticles. This hierarchical architecture offers good ion/electron transport channels for better electrochemical characteristics.The maximum specific capacitance was found to be 548.4 F/g at a scan rate of 10 mV/s, and also from the galvanostatic charge-discharge curve, it was 696.8 F/g at a current density of 1.5 A/g. Additionally, capacitance retention is 84.4% and coulombic efficiency is 97% even after 5000 cycles. The energy density is 47.4 Wh kg -1 and the power density is 853.2 W kg -1 . These results suggest that porous carbon composites are cost-effective, technologically unique, and eco-friendly for environmental supercapacitor applications. porous carbon composite specific capacitance high energy density cycle stability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Highlights To study the developed activated porous carbon derived from bio-waste based date seeds and cobalt oxide composites by a facile one -step carbonization The CV measured specific capacitance was 548.4 F/g at a scan rate of 10 mV/s. The GCD reveals a high specific capacitance of 696.8 F/g at a current density of 1.5 A/g. 1. Introduction In recent years, energy materials have drawn a lot of attention due to the rising problems of the global energy crisis, environmental pollution, and the expanding need for portable electronic devices and high-performance energy storage systems [1]. Thus, finding a new unique material with a suitable large surface area and developing an efficient and compactable technique to enhance the energy storage capacity and conversion [2]. Presently, the supercapacitor stands out among other energy storage devices, and it has drawn a lot of interest due to its advantages of having a high power density, fast charging-discharging, and a long cycling life span [3]. Based on charge storage techniques, supercapacitors can be classified into electrical double-layer capacitors (EDLC) and faradic redox capacitors. The ion adsorption at the electrode and electrolyte interface is what causes the capacitance of the EDLC. Carbon materials are the most typical electrode material used in EDLC due to their exceptional thermal and chemical stability, multi-porous structure, and reasonably good electrical conductivity [4]. Most recently, graphene, carbon nanotubes, activated carbon, carbon nitride, and carbon nanofibers are just a few examples of high- specific surface area, carbon materials that can be used as electrodes for double-layer capacitors [5]. Among carbon-based materials, activated porous carbon has received more attention as a result of its enormous specific surface area (SSA), superior conductivity, and environmental friendliness. Additionally, the heteroatoms can greatly improve their ability to transmit electrons [6]. Another type of capacitor that typically makes use of metal oxides or metal hydroxides is the Faraday pseudo-capacitor. This pseudocapacitance results from quick redox reactions between metal oxides and electrolytes. Metal oxides, such as RuO 2 , CoO 2 , SnO 2 , FeO 2 , MnO 2 , NiO, etc., have pseudocapacitance in addition to the usual double-layer capacitance, which gives them a higher capacitance than carbon-based materials. On the other hand, many natural materials are generally abundant, renewable, inexpensive, and environmentally benign compared to artificial templates and precursors. As is well known, with the development of industry and the economy, more and more waste, such as biomass waste, is generated. Since the cost of handling environmental waste is on the rise, recycling bio-waste or converting it into useful products is crucial to preserving the environment [7]. Biomass wastes contain high proportions of carbohydrates such as cellulose and lignin, which can be used to develop cheap activated carbon [8]. Using natural bio-waste materials to construct carbon materials has received extensive attention, such as tobacco waste [9], orange peel [10], palm kernel shell [11], potato starch [12], and ramie [13]. It has attracted a lot of interest because of its natural bio-waste for the synthesis of activated carbon and as a sustainable processing technique. The key benefits of biomass are its availability, cheap price, and renewable nature [14]. The physical and chemical activation processes are used to create activated carbon. Since it results in the development of a greater pore volume and surface area, the chemical activation method is the most preferred one [15]. The significant chemical activators are KOH, K 2 CO 3 , ZnCl 2 , Na 2 Co 3 , NaOH, H 2 SO 4 , etc [16–18]. Potassium hydroxide is the most efficient and environmentally friendly activating agent when compared to other activating agents, which is why it is more recommended in the chemical activation process for making porous activated carbon. Several electrode materials, including transition metal oxides or hydroxides and conducting polymers such as PANI [19], NiO [20], MnO 2 [21], RuO 2 [22], etc., have been selected to enhance the storage capability of pseudocapacitors. However, their performance and stability are still lacking due to their relatively low rate. Regarding costs, some are limited to a select few applications [23]. Cobalt oxides have been proposed as a suitable substitute electrode material for pseudocapacitors due to their various stable oxidation states (Co 2+ , Co 3+ , and Co 4+ ), low cost, non-noble nature, and high theoretical specific capacitance [24]. However, cobalt oxide suffers from poor electrical conductivity and limited cycling stability, which hinder its practical application. To address this limitation, integrate cobalt oxide with porous carbons to form composite materials that combine the advantages of both porous carbon and cobalt oxide. The porous carbon acts as a conductive network, facilitating electron transport throughout the electrode, while the cobalt oxide component contributes to the overall capacitance of the composite. The fabrication of porous carbon and cobalt oxide composites for supercapacitors involves various techniques such as hydrothermal synthesis [25], template-assisted methods [26], or pyrolysis treatment [27]. For instance, Dongmei Zhao et al. prepared nitrogen-doped porous carbon composites with Co NPs by a simple one-step carbonization method [28]. G. Alaei et al. synthesized cobalt oxide hierarchical nanostructure (Co 3 O 4 -HNS) onto carbon fibre substrate (CFS/Co 3 O 4 -HNS) by a one-pot hydrothermal process [29]. Nititorn Kenyota et al. synthesized activated carbon and cobalt oxide nanocomposite (AC/Co 3 O 4 ) by a solid-state reaction process [30]. Khabibulla et al. prepared activated carbon/cobalt oxide composites (Co@AC) by polycondensation reaction and pyrolysis to enhance the performance of the supercapacitor [31]. However, these strategies imply a synthesis or a relatively high production cost and therefore present practical difficulties. The investigation of a simple route to synthesize Co 3 O 4 /carbon hybrids derived from date seed waste with tunable pore size and interfacial properties is another promising direction in this work. The electrochemical energy storage and electrode performance of electrodes synthesized with date seed- derived activated carbon and cobalt oxide composites have been examined. A waste to wealth based approach is used in this work to demonstrate the feasibility of bulk production of this kind of material at a cheaper cost. In this paper, we demonstrate a facial and sustainable one-step synthesis of hierarchical high-porous carbon/cobalt oxide nanoparticles (PCCo) composite materials derived from bio-waste date seed. A compound chemical activating agent consisting of potassium hydroxide (KOH) was used to convert the bio-waste date seed into porous carbon (PC) while also depositing cobalt oxide (Co 3 O 4 ) nanoparticles simultaneously on the surface of PC. The PCCo composite material has a hierarchical porous structure, which improves the electrochemical performance of the material and, therefore, makes it very suitable for use in supercapacitors. The electrochemical performance of the PCCo-0.4 electrodes was tested using a three-electrode system. The specific capacitance observed from CV is 548.4 F/g at a scan rate of 10 mV/s. The GCD reveals a high specific capacitance of 696.8 F/g at a current density of 1.5 A/g. Additionally, the capacitance retention is 84.4% and the coulombic efficiency is 97%, even after 5000 cycles. The energy density is 47.4 Wh kg -1 and the power density is 853.2 W kg -1 . Therefore, these unique properties enable the material to become a promising high-performance electrode material for supercapacitors. Moreover, it addresses the problem of bio-waste recycling and provides a method for generating advanced materials for energy storage at the industrial level. 2. Experimental techniques 2.1. Chemicals used The date seeds, are extracted from date fruit, cobalt oxide (Co 3 O 4 , 50 nm, 99.5% trace metal basis), potassium hydroxide (KOH), charcoal, and polyvinylidene fluoride (PVDF), were purchased from Sigma Aldrich, India. The N-Methyl-2-pyrrolidone (NMP) solvent and double-distilled water (DDW) were employed in the synthesis process. 2.2. Synthesis of porous carbon-cobalt oxide composite Porous carbon (PC) was synthesized by using date seeds as the carbon precursor, and KOH was used as an active agent through the chemical reaction method. The date seeds were washed with double-distilled water (DDW) and dried at 100 in the microwave oven. Then, they ground it using mortar to produce a fine powder. Then 0.2 g of Co 3 O 4 was added to 20 mL of 1 M KOH and magnetically stirred for 1 h to create a homogeneous suspension. Next, add 10 g date seed powder and heat up to 120 o C for 12 h in the microwave oven. The product was crushed and carbonized in a tubular furnace at 650 o C for 2 h under N 2 atmosphere. The product was filtered repeatedly with DDW and dried in the microwave oven at 60 for 8 h, as shown in Scheme (1). Samples prepared at different concentrations of cobalt oxide (0, 0.2, & 0.4 g) were labelled PC, PCCo-0.2, and PCCo-0.4, respectively. 2. 3. Characterization techniques The surface morphology of the materials was investigated by field emission scanning electron microscopy (Sigma Zeiss FESEM) and high-resolution transmission microscopy (HR-TEM)(JEOL JEM-F-200). The crystallinity of the material was analysed by powder X-ray diffraction (XRD) using Rigaku Miniflex 500 diffractometer Cu K radiation. The chemical change was obtained by a Fourier transform infrared spectrometer (FTIR, model ALPHA BURKUE) in the range of 500-4000 cm -1 . Raman spectra were captured using (a LabRAM HR evalution visible NIR (HORIBA) and Ar ion laser with a radiation wavelength of 532 nm between 500 and 3000 cm -1 . 2. 4. Electrochemical measurement The process of preparing the working electrode was as follows: The synthesized PCCo materials, polyvinylidene fluoride (PVDF), charcoal at a weight ratio of 90:5:5, and NMP were combined to create a slurry. The resulting mixture is then coated on a (1 x 1) cm stainless steel strip and dried for 8 h at 60 °C in a vacuum oven [32]. A three-electrode configuration was employed to study the electrochemical behavior in the presence of a 3 M KOH electrolyte. The counter electrode was composed of a platinum wire, while an Ag/AgCl electrode served as the reference electrode. The cyclic voltammetry, galvanostatic charging discharging, and electrochemical impedance spectroscopy have been carried out and studied using the CHI 660E model. 3. Results and duscussion 3.1. X-ray Diffraction Analysis X-ray diffraction (XRD) was used to analyse the crystal structure of PC, PCCo-0.2, and PCCo-0.4 composites. Fig. 1. presents the XRD spectra of the PC, PCCo-0.2, and PCCo-0.4 composites. The PC had two broad characteristic peaks located at 24 and 44.3°, which could be attributed to the (002) and (100) planes of the graphitic structure present in the PC [33, 34]. The graphite phase is a form of conductivity carbon that is expected to be beneficial to reduce the resistance of composites during electrochemical processes [35]. After Co 3 O 4 doping, numerous defects were observed, which resulted in the reduction of the intensity of the peak at 24° and the peak at 44.3° disappeared. However, the PCCo-0.2 showed wide diffraction peak at 24°, which are characteristic of the (002) plane of graphitic carbons, suggesting that the graphitization of date seed had not been significantly affected and it can offer high electrical conductivity. On the other hand, the PCCo-0.2 produced new diffraction peaks at 36.5°, and 44°, which are the characteristic peaks of the (311), and (400) crystal planes of Co 3 O 4 [36]. Following the increase in Co 3 O 4 loading, the 24° broad peak suggests that the strong oxidizing ability could not destroy the porous carbon structure. Concurrently, the PCCo-0.4 exhibited an additional diffraction peaks at 42°, and 61°, linked to the crystal planes of (002), and (022) of CoO (JCPDS No. 01-075-0393), signifying the successful fabrication of the PCCo composites [37]. 3. 2. FTIR analysis The FTIR spectra of the PC, PCCo-0.2, and PCCo-0.4 composites are shown in Fig. 2. It is observed that the characteristic peaks are at 3734, 2338.2, 1692.2, and 1527.2 cm -1 . The band at 3734 cm -1 is assigned to the stretching vibration of the O-H mode of the hydroxyl functional group [38]. The peak observed at 2338.2 cm -1 is assigned to the CO 2 molecules as a result of the interaction of porous carbon and composites with CO 2 molecules from the atmosphere [39], and at 1692.2 cm -1 it is attributed to the stretching vibration of the C=O bond [40]. The band at 1527.2 cm -1 is attributed to C=C aromatic stretching vibration [35]. Additionally, a new peak was found at 730 cm -1 in PCCo-0.2 in relation to the vibrations of cobalt oxide bonds [41]. In this perspective, new peaks at 683.4 and 565 cm -1 for PCCo-0.4 indicate composite influence associated with vibrations of cobalt oxide bonds [42]. The existing functional groups have a substantial impact on the hydrophilicity of the carbon surface, which is a crucial component in increasing specific capacitance. The FTIR results confirm the presence of C, O, and Co elements in the PCCo-0.4 composite, which is agreement with the analysis of elemental mappings. 3. 3. FESEM image analysis FESEM images provide the morphology and microstructural arrangement of PC, PCCo-0.2, and PCCo-0.4 composites, as shown in Fig. 3. Fig. 3(a) demonstrated roughness and interconnected pores with hierarchical-like morphologies on the surface for PC, which is a material advantage to insert more ions into existing pores should the volume to surface charge ratio change, which may improve the electrochemical performance of the device [43, 44]. Fig. 3(b) reveals that the irregular porous structure should facilitate the contact of more active sites, which may help to easily diffuse the charges during the electrochemical mechanism through electrolytes in the case of the PCCo-0.2 composite. Moreover, the interconnected porous networks became non-existent and were replaced by exposed large pores in PCCo-0.2. This was due to the incorporation of Co 3 O 4 nanoparticles during the carbonization process. It is also interpreted that it boosts ion transport and increases the density of the active centre [9]. PCCo-0.4 is depicted in Fig. 3(c), which reveals that the activated carbon possesses a rough porous structure with large open channels and the Co 3 O 4 nanoparticles dispersed onto the porous carbon surface. The existence of open channels forms porous carbon, which allows ions to access a larger surface and a route track for transport during the charge storage process [10]. Additionally, elemental mapping has also been carried out to confirm the presence of various elements in the PCCo composite, as depicted in Fig. 3(e-f). The EDS results revealed the presence of Co, O, and C elements in the PCCo composite. 3. 4. HR-TEM image analysis HR-TEM analysis was carried out to determine the dispersion of cobalt oxide nanoparticles on the activated porous carbon surface, as shown in Fig. 4(a & b). It is also seen that contrasts of dark and light morphology correspond to the porous structure and the pore channels, respectively [45]. The HR-TEM image of PCCo-0.4 shows that the Co 3 O 4 nanoparticles are well-integrated in the porous carbon matrix in Fig. 4 (c). For Fig. 4(d), the lengths of cobalt oxide particles are 326.94, 297.09, and 164.94 nm. Fig. 5(e), which displays the HR-TEM image of PC with an apparent spacing of 0.34 nm, reflects the (002) lattice plane of graphite carbon [46]. The SAED Fig. 4(g) inset represents the (002) plane of graphite carbon from the inside out. The HR-TEM image of the PCCo-0.4 composite is as shown in Fig. 4 (f). It is seen that the lattice fringes of the black nanoparticles were calculated to be around 0.24 and 0.20 nm, which correspond to the (311) and (400) planes of Co 3 O 4 , respectively [47, 48]. In addition, it is also seen that the presence of Co 3 O 4 is shown by the selected-area electron diffraction (SAED) patterns cited in figure 4 (h), which agree with the results of the XRD investigation. 3.5. Raman spectroscopy analysis The Raman spectra of the PC, PCCo-0.2, and PCCo-0.4 composites between 500 and 3000 cm -1 in wavelength are displayed in Fig. 5. It is observed that the two peaks D band (at 1370 cm -1 ) and G band (at 1590 cm -1 ) are linked to the presence of dis-orders caused by the sp 3 carbon configuration and the in-plane bond-stretching mode of the sp 2 carbon configuration, respectively [49, 50]. By comparing the intensity of the two bands (I D /I G ), it is usually possible to identify defects in the surface structure of carbon materials [51]. The I D /I G values for the PCCo-0.4 (0.720) and PCCo-0.2 (0.692) composites were higher than those for pure PC (0.660). An increase in the intensity ratio of I D /I G indicates a decrease in the dimensions of the sp 2 domains within the plane and a structurally organized crystalline pattern of PCCo-0.2 and PCCo-0.4 composites. This suggests the presence of imperfections caused by the incorporation of Co 3 O 4 nanoparticles into porous carbon, resulting in the formation of voids within the porous carbon structure. 3.6. Electrochemical performance 3.6.1 Cyclic Voltammetry Cyclic voltammetry was used to investigate the electrochemical performance of electrodes, as shown in Fig. 6, and the data was used to estimate the specific capacitance of the samples at various scan rate values. The CV study was carried out in a 3M KOH aqueous electrolyte medium with a potential window ranging from -0.6 V to +0.6 V and scan rates ranging from 10 mV/s to 50 mV/s for PC, PCCo-0.2, and PCCo-0.4 composites. Fig. 6(a, b, & c) show the height of the peak currents increases with scan rate and a gradual shift towards a higher potential value (oxidation process), whereas a shift to a lower potential was noticed (reduction process). As the scan rate increases, the charging current increases, indicating that more current is allowed to flow. The equation is used to determine specific capacitance; Where Csp is the specific capacitance, I is the current , ∆𝑉 is the potential window, and ‘ m’ is the mass of the active material. The estimated specific capacitance value for the PC sample is 207 F/g at a scan rate of 10 mV/s; the PCCo-0.2 and PCCo-0.4 composites showed specific capacitance values of 321 and 548.4 F/g, respectively. The cyclic voltammograms show typical redox rectangle forms with anodic and cathodic peaks, clearly indicating the pseudocapacitive behavior of the material [52]. Fig. 6(d) also illustrates that the PCCo-0.4 composite exhibits a significantly larger capacitance than the PC and PCCo-0.2 composites. The specific capacitance of the activated carbon has consequently been improved by the addition of Co, as could be safely asserted. Additionally, the use of aqueous KOH as the electrolyte rather than inorganic ones, considering that the latter offers a larger ionic concentration and lower resistance, may have high power and capacitance [53]. 3.6.2 Galvanostatic Charging-Discharging analysis The GCD analysis of PC, PCCo-0.2, and PCCo-0.4 composite electrodes was conducted at multiple current densities varying between 1.5 and 2.25 A/g with a voltage window ranging from -0.6 to +0.6 V. The GCD curve shows a symmetric triangular shape, which indicates the pseudocapacitance behavior. The discharge time gets increased with the decrease in the CD, which is due to the limitation of charge transport diffusion coefficients at higher current densities [54]. Which are diffusion-controlled processes as well as having great reversibility. The formula used to determine the specific capacitance from the GCD data is the below equation; Where Csp is the specific capacitance, I is the current, ∆𝑡 is the discharge time, ∆𝑉 is the potential Window, and m is the mass of the active material. The specific capacitances from the discharge curves are 375 F/g (PC), 515.4 F/g (PCCo-0.2), and 696.8 F/g (PCCo-0.4) at a current density of 1.5 A/g in 3M KOH electrolyte, as shown in Fig. 7(a, b & c). Furthermore, compared with other values, the specific capacitance of PCCo-0.4 is significantly better than that of some cobalt-based materials like PC and PCCo-0.2, as revealed in Fig. 7(d). It can be concluded that ion diffusion and electron transport play important roles in the performance of supercapacitor [55]. Commonly, it is believed that materials with porous structures should be better for energy storage due to the high surface area and the channels for fast ion diffusion [56]. 3.6.3 Electrochemical Impedance Analysis The EIS spectra are used to study the exact electrical conductivity of poroused PC, PCCo-0.2, and PCCo-0.4 electrode material at room temperature in the frequency range 1–10 5 Hz. In general, the impedance curves present two partially overlapped semicircles in the high and medium frequency regions and an inclined line in the low frequency region [57]. It is obvious that the diameters of the semicircles for PC and PCCo-0.2 are larger than those for PCCo-0.4, indicating that the hybrid samples possess much lower charge transfer resistance [26, 58], which is confirmed by the inset figure fitting results as illustrated in Fig. 8(a). According to the results, the Rct of PC and PCCo-0.2 is 4.2, and 3.7 Ω, much higher than that of PCCo-0.4 (1.2 Ω). In this investigation, the sole disparity in the electrodes lies in the composite matrix of cobalt oxide and the resultant morphology. Therefore, the variations in impedance among the five electrodes manifest the influences of the cobalt oxide. This discernment can be attributed to the morphology and arrangement of the cobalt oxide in the porous carbon structure. It is observed that the PCCo-0.4 electrode SCs device has a high energy density (ED) of 47.4 Whkg -1 at a power density (PD) of 853.2 Wkg -1 and decreases to 18.8 Whkg -1 at a maximum PD of 1358.2 Wkg -1 , as shown by the Ragone plot in Fig. 8(b). This value is higher or comparable to other porous carbon/cobalt oxide composites for SCs reported recently, such as BIC-Co 3 O 4 (17 Wh kg -1 , 184 W kg -1 ) [59], Co 3 O 4 @NOPC-200 (42.5 Wh kg -1 , 746 W kg -1 ) [60], Co 3 O 4 @MBC/NF (19.74 Wh kg -1 , 560 W kg -1 ) [47], (3DPC)/Co 3 O 4 (21.1 Wh kg -1 , 790 W kg -1 ) [61], Ni-Co-S@N-pCNFs (21.6 Wh kg -1 , 134.9 W kg -1 ) [62], as shown in Table (2). Table. 2: Comparison of performance of this work with recent work on porous carbon and cobalt oxide composites In addition, the GCD analysis is to investigate the reliability of the SCs electrode materials, and it was noticed that PCCo-0.4 exhibits long stability cycling and more energy storage systems. The capacitance retention of the PCCo-0.4 electrode is still 84.4%, as shown in Fig. 8(c). The supercapacitor's coulombic efficiency (η) was calculated using the following equation; Where Δtd and Δtc represent the discharge and charge times, respectively. There is no apparent IR drop, and all curves are linear and symmetrical, even after showing 5000 cycles at a CD of 1 A/g. The proposed electrode material can be attributed to the electrode matrix's insignificant loss during the charging-discharging cycle [63, 64]. 4. Conclusions In conclusion, we successfully used a facile one-step carbonization and activation process to synthesize activated porous carbon derived from date seeds and cobalt oxide composites. The resulting PCCo revealed a highly porous microstructure with an improvement in crystallinity owing to the Co 3 O 4 particles’ catalytic graphitization, which helped to convert some of the amorphous carbon into more ordered graphite. The PCCo-0.4 electrode supercapacitor devices showed a high specific capacitance, extended lifetime, and low outflow current. The GCD values in the PCCo-0.4 electrode have a high capacitance of 671 F/g at a current density of 1.5 A/g. At a scan rate of 10 mV/s, the CV capacitance is 496 F/g. The SSC PCCo-0.4//PCCo-0.4 device exhibited an energy density of 47.4 Wh kg − 1 and a power density of 853.2 W kg − 1 with capacitance retention of 84.4% and coulombic efficiency of 97% even after 5000 cycles of charging and discharging at 1 A/g. In addition to a cost-effective and technologically unique method for using environmental supercapacitor applications, this study also presented a novel carbon source that is inexpensive, easy to use, and favorable to the environment. Declarations Compliance with ethical standards Conflict of authors interest declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution Abdullah Ba shbil- work carried out & prepare this manuscriptNagaraju Y S- Support to literature review Ganesha H-Synthesis of methodsVeeresh S-CharacterizationSuresh D S-Electrode fabrication & experimental measurementVijaykumar S P- plot graphSapna Sharanappa-Analysis Devendrappa H - Superivisor Acknowledgement Article is prepare by own without external References S. J. Rajasekaran and V. Raghavan, “Facile synthesis of activated carbon derived from Eucalyptus globulus seed as efficient electrode material for supercapacitors,” Diam. Relat. Mater. , vol. 109, no. February, p. 108038, 2020, doi: 10.1016/j.diamond.2020.108038. R. R. Salunkhe, Y. V. Kaneti, and Y. Yamauchi, “Metal-Organic Framework-Derived Nanoporous Metal Oxides toward Supercapacitor Applications: Progress and Prospects,” ACS Nano , vol. 11, no. 6, pp. 5293–5308, 2017, doi: 10.1021/acsnano.7b02796. Y. 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Liu et al. , “Three-dimensional hierarchical and interconnected honeycomb-like porous carbon derived from pomelo peel for high performance supercapacitors,” J. Solid State Chem. , vol. 257, no. July, pp. 64–71, 2018, doi: 10.1016/j.jssc.2017.07.033. Y. Gao et al. , “Chemical activation of carbon nano-onions for high-rate supercapacitor electrodes,” Carbon N. Y. , vol. 51, no. 1, pp. 52–58, 2013, doi: 10.1016/j.carbon.2012.08.009. Scheme Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. 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capacitance variation for different scan rates ranging from 10 to 50 mV/s.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5236326/v1/d0b30b608d3b74627b5fe82a.png"},{"id":70949798,"identity":"ecb19243-3581-4966-8a56-9e6109d295cd","added_by":"auto","created_at":"2024-12-09 13:35:36","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":118507,"visible":true,"origin":"","legend":"\u003cp\u003eGCD curve for (a) PC, (b) PCCo-0.2, (c) PCCo-0.4, and (d) specific capacitance at various current densities from 1.5 to 2.25 A/g.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-5236326/v1/05172bdb0dfe157e278bf3d1.png"},{"id":70949801,"identity":"11e0c505-85e1-4be1-9409-3f9b7146f19a","added_by":"auto","created_at":"2024-12-09 13:35:36","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":87243,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Nyquist plots and (b) Ragone plots of PCCo-0.4; (c) capacitance retention and coulombic efficiency of PCCo-0.4 up to 5000 cycles.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-5236326/v1/e0c3bf7a35dbd118a8c9af8e.png"},{"id":70953750,"identity":"0f417cc8-5544-431a-a33e-da337a1dcc61","added_by":"auto","created_at":"2024-12-09 13:59:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2144782,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5236326/v1/91a1e1df-ebed-40b3-9748-743f61cb6b3b.pdf"},{"id":70949792,"identity":"0ea7e1cd-759b-48c2-9a4f-8eaae7a89239","added_by":"auto","created_at":"2024-12-09 13:35:36","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":371017,"visible":true,"origin":"","legend":"","description":"","filename":"GraphicalAbstarct.docx","url":"https://assets-eu.researchsquare.com/files/rs-5236326/v1/dd4781ff742f9087fc9a3f76.docx"},{"id":70949799,"identity":"10c75d96-1fc0-47a6-b485-6538fae65554","added_by":"auto","created_at":"2024-12-09 13:35:36","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":370942,"visible":true,"origin":"","legend":"","description":"","filename":"Scheme.docx","url":"https://assets-eu.researchsquare.com/files/rs-5236326/v1/88c0b03de585383e5e7b120a.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Facile synthesis of hierarchical morphology highly porous carbon cobalt oxide composite from one-step carbonization of bio-waste for energy storage application","fulltext":[{"header":"Highlights","content":"\u003cul\u003e\n \u003cli\u003eTo study the developed activated porous carbon derived from bio-waste based date seeds and cobalt oxide composites by a facile one -step carbonization\u003c/li\u003e\n \u003cli\u003eThe CV measured specific capacitance was 548.4 F/g at a scan rate of 10 mV/s.\u003c/li\u003e\n \u003cli\u003eThe GCD reveals a high specific capacitance of 696.8 F/g at a current density of 1.5 A/g.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"1. Introduction","content":"\u003cp\u003eIn recent years, energy materials have drawn a lot of attention due to the rising problems of the global energy crisis, environmental pollution, and the expanding need for portable electronic devices and high-performance energy storage systems [1]. Thus, finding a new unique material with a suitable large surface area and developing an efficient and compactable technique to enhance the energy storage capacity and conversion [2]. Presently, the supercapacitor stands out among other energy storage devices, and it has drawn a lot of interest due to its advantages of having a high power density, fast charging-discharging, and a long cycling life span [3]. Based on charge storage techniques, supercapacitors can be classified into electrical double-layer capacitors (EDLC) and faradic redox capacitors. The ion adsorption at the electrode and electrolyte interface is what causes the capacitance of the EDLC. Carbon materials are the most typical electrode material used in EDLC due to their exceptional thermal and chemical stability, multi-porous structure, and reasonably good electrical conductivity [4]. Most recently, graphene, carbon nanotubes, activated carbon, carbon nitride, and carbon nanofibers are just a few examples of high- specific surface area, carbon materials that can be used as electrodes for double-layer capacitors [5]. Among carbon-based materials, activated porous carbon has received more attention as a result of its enormous specific surface area (SSA), superior conductivity, and environmental friendliness. Additionally, the heteroatoms can greatly improve their ability to transmit electrons [6]. Another type of capacitor that typically makes use of metal oxides or metal hydroxides is the Faraday pseudo-capacitor. This pseudocapacitance results from quick redox reactions between metal oxides and electrolytes. Metal oxides, such as RuO\u003csub\u003e2\u003c/sub\u003e, CoO\u003csub\u003e2\u003c/sub\u003e, SnO\u003csub\u003e2\u003c/sub\u003e, FeO\u003csub\u003e2\u003c/sub\u003e, MnO\u003csub\u003e2\u003c/sub\u003e, NiO, etc., have pseudocapacitance in addition to the usual double-layer capacitance, which gives them a higher capacitance than carbon-based materials.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOn the other hand, many natural materials are generally abundant, renewable, inexpensive, and environmentally benign compared to artificial templates and precursors. As is well known, with the development of industry and the economy, more and more waste, such as biomass waste, is generated. Since the cost of handling environmental waste is on the rise, recycling bio-waste or converting it into useful products is crucial to preserving the environment [7]. Biomass wastes contain high proportions of carbohydrates such as cellulose and lignin, which can be used to develop cheap activated carbon\u0026nbsp;[8]. Using natural bio-waste materials to construct carbon materials has received extensive attention, such as tobacco waste\u0026nbsp;[9], orange peel\u0026nbsp;[10], palm kernel shell\u0026nbsp;[11], potato starch\u0026nbsp;[12], and ramie\u0026nbsp;[13]. It has attracted a lot of interest because of its natural bio-waste for the synthesis of activated carbon and as a sustainable processing technique. The key benefits of biomass are its availability, cheap price, and renewable nature\u0026nbsp;[14].\u0026nbsp;The physical and chemical activation processes are used to create activated carbon. Since it results in the development of a greater pore volume and surface area, the chemical activation method is the most preferred one [15]. The significant chemical activators are KOH, K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e, ZnCl\u003csub\u003e2\u003c/sub\u003e, Na\u003csub\u003e2\u003c/sub\u003eCo\u003csub\u003e3\u003c/sub\u003e, NaOH, H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e, \u0026nbsp;etc\u0026nbsp;[16\u0026ndash;18]. Potassium hydroxide is the most efficient and environmentally friendly activating agent when compared to other activating agents, which is why it is more recommended in the chemical activation process for making porous activated carbon.\u003c/p\u003e\n\u003cp\u003eSeveral electrode materials, including transition metal oxides or hydroxides and conducting polymers such as PANI [19], NiO [20], MnO\u003csub\u003e2\u003c/sub\u003e [21], RuO\u003csub\u003e2\u003c/sub\u003e [22], etc., have been selected to enhance the storage capability of pseudocapacitors. However, their performance and stability are still lacking due to their relatively low rate.\u0026nbsp;Regarding costs, some are limited to a select few applications\u0026nbsp;[23]. Cobalt oxides have been proposed as a suitable substitute electrode material for pseudocapacitors due to their various stable oxidation states (Co\u003csup\u003e2+\u003c/sup\u003e, Co\u003csup\u003e3+\u003c/sup\u003e, and Co\u003csup\u003e4+\u003c/sup\u003e), low cost, non-noble nature, and high theoretical specific capacitance\u0026nbsp;[24]. However, cobalt oxide suffers from poor electrical conductivity and limited cycling stability, which hinder its practical application. To address this limitation, integrate cobalt oxide with porous carbons to form composite materials that combine the advantages of both porous carbon and cobalt oxide. The porous carbon acts as a conductive network, facilitating electron transport throughout the electrode, while the cobalt oxide component contributes to the overall capacitance of the composite. The fabrication of porous carbon and cobalt oxide composites for supercapacitors involves various techniques such as hydrothermal synthesis [25], template-assisted methods\u0026nbsp;[26], or pyrolysis treatment\u0026nbsp;[27]. For instance,\u0026nbsp;Dongmei Zhao et al. prepared nitrogen-doped porous carbon composites with Co NPs by a simple one-step carbonization method\u0026nbsp;[28]. G. Alaei et al. synthesized cobalt oxide hierarchical nanostructure (Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-HNS) onto carbon fibre substrate (CFS/Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-HNS) by a one-pot hydrothermal process\u0026nbsp;[29]. Nititorn Kenyota et al. synthesized activated carbon and cobalt oxide nanocomposite (AC/Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e) by a solid-state reaction process\u0026nbsp;[30]. Khabibulla et al. prepared activated carbon/cobalt oxide composites (Co@AC) by polycondensation reaction and pyrolysis to enhance the performance of the supercapacitor\u0026nbsp;[31]. However, these strategies imply a synthesis or a relatively high production cost and therefore present practical difficulties. The investigation of a simple route to synthesize Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/carbon hybrids derived from date seed waste with tunable pore size and interfacial properties is another promising direction in this work. The electrochemical energy storage and electrode performance of electrodes synthesized with date seed- derived activated carbon and cobalt oxide composites have been examined. A waste to wealth based approach is used in this work to demonstrate the feasibility of bulk production of this kind of material at a cheaper cost.\u003c/p\u003e\n\u003cp\u003eIn this paper, we demonstrate a facial and sustainable one-step synthesis of hierarchical high-porous carbon/cobalt oxide nanoparticles (PCCo) composite materials derived from bio-waste date seed. A compound chemical activating agent consisting of potassium hydroxide (KOH) was used to convert the bio-waste date seed into porous carbon (PC) while also depositing cobalt oxide (Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e) nanoparticles simultaneously on the surface of PC.\u0026nbsp;The PCCo composite material has a hierarchical porous structure, which improves the electrochemical performance of the material and, therefore, makes it very suitable for use in supercapacitors. The electrochemical performance of the PCCo-0.4 electrodes was tested using a three-electrode system. The specific capacitance observed from CV is 548.4 F/g at a scan rate of 10 mV/s. The GCD reveals a high specific capacitance of 696.8 F/g at a current density of 1.5 A/g. Additionally, the capacitance retention is 84.4% and the coulombic efficiency is 97%, even after 5000 cycles. The energy density is 47.4 Wh kg\u003csup\u003e-1\u003c/sup\u003e and the power density is 853.2 W kg\u003csup\u003e-1\u003c/sup\u003e. Therefore, these unique properties enable the material to become a promising high-performance electrode material for supercapacitors. Moreover, it addresses the problem of bio-waste recycling and provides a method for generating advanced materials for energy storage at the industrial level.\u003c/p\u003e"},{"header":"2. Experimental techniques","content":"\u003cp\u003e\u003cstrong\u003e2.1. Chemicals used\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe date seeds, are extracted from date fruit, cobalt oxide (Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, 50 nm, 99.5% trace metal basis), potassium hydroxide (KOH), charcoal, and polyvinylidene fluoride (PVDF), were purchased from Sigma Aldrich, India. The N-Methyl-2-pyrrolidone (NMP) solvent and double-distilled water (DDW) were employed in the synthesis process.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. Synthesis of porous carbon-cobalt oxide composite\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePorous carbon (PC) was synthesized by using date seeds as the carbon precursor, and KOH was used as an active agent through the chemical reaction method. The date seeds were washed with double-distilled water (DDW) and dried at 100 \u0026nbsp; in the microwave oven. Then, they ground it using mortar to produce a fine powder. Then 0.2 g of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e was added to 20 mL of 1 M KOH and magnetically stirred for 1 h to create a homogeneous suspension. Next, add 10 g date seed powder and heat up to 120 \u003csup\u003eo\u003c/sup\u003eC for 12 h in the microwave oven. The product was crushed and carbonized in a tubular furnace at 650 \u003csup\u003eo\u003c/sup\u003eC for 2 h under N\u003csub\u003e2\u003c/sub\u003e atmosphere. The product was filtered repeatedly with DDW and dried in the microwave oven at 60 \u0026nbsp; for 8 h, as shown in Scheme (1). Samples prepared at different concentrations of cobalt oxide (0, 0.2, \u0026nbsp;\u0026amp; 0.4 g) were labelled PC, PCCo-0.2, and PCCo-0.4, respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. 3. Characterization techniques\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe surface morphology of the materials was investigated by field emission scanning electron microscopy (Sigma Zeiss FESEM) and high-resolution transmission microscopy (HR-TEM)(JEOL JEM-F-200). The crystallinity of the material was analysed by powder X-ray diffraction (XRD) using Rigaku Miniflex 500 diffractometer Cu K\u0026nbsp;\u0026nbsp;radiation. The chemical change was obtained by a Fourier transform infrared spectrometer (FTIR, model ALPHA BURKUE) in the range of 500-4000 cm\u003csup\u003e-1\u003c/sup\u003e. Raman spectra were captured using (a LabRAM HR evalution visible NIR (HORIBA) and Ar ion laser with a radiation wavelength of 532 nm between 500 and 3000 cm\u003csup\u003e-1\u003c/sup\u003e. \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. 4.\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eElectrochemical measurement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe process of preparing the working electrode was as follows: The synthesized PCCo materials, polyvinylidene fluoride (PVDF), charcoal at a weight ratio of 90:5:5, and NMP were combined to create a slurry. The resulting mixture is then coated on a (1 x 1) cm stainless steel strip and dried for 8 h at 60 \u0026deg;C in a vacuum oven [32]. A three-electrode configuration was employed to study the electrochemical behavior in the presence of a 3 M KOH electrolyte. The counter electrode was composed of a platinum wire, while an Ag/AgCl electrode served as the reference electrode. The cyclic voltammetry, galvanostatic charging discharging, and electrochemical impedance spectroscopy have been carried out and studied using the CHI 660E model.\u003c/p\u003e"},{"header":"3. Results and duscussion","content":"\u003cp\u003e\u003cstrong\u003e3.1. X-ray Diffraction Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eX-ray diffraction (XRD) was used to analyse the crystal structure of PC, PCCo-0.2, and PCCo-0.4 composites. Fig. 1. presents the XRD spectra of the PC, PCCo-0.2, and PCCo-0.4 composites. The PC had two broad characteristic peaks located at 24\u0026nbsp;and 44.3\u0026deg;, which could be attributed to the (002) and (100) planes of the graphitic structure present in the PC [33, 34]. The graphite phase is a form of conductivity carbon that is expected to be beneficial to reduce the resistance of composites during electrochemical processes [35].\u0026nbsp;After Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e doping, numerous defects were observed, which resulted in the reduction of the intensity of the peak at 24\u0026deg; and the peak at 44.3\u0026deg; disappeared. However, the PCCo-0.2 showed wide diffraction peak at 24\u0026deg;, which are characteristic of the (002) plane of graphitic carbons, suggesting that the graphitization of date seed had not been significantly affected and it can offer high electrical conductivity. On the other hand, the PCCo-0.2 produced new diffraction peaks at 36.5\u0026deg;, and 44\u0026deg;, which are the characteristic peaks of the (311), and (400) crystal planes of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e [36]. Following the increase in Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e loading, the 24\u0026deg; broad peak suggests that the strong oxidizing ability could not destroy the porous carbon structure. Concurrently, the PCCo-0.4 exhibited an additional diffraction peaks at 42\u0026deg;, and 61\u0026deg;, linked to the crystal planes of (002), and (022) of CoO (JCPDS No. 01-075-0393), signifying the successful fabrication of the PCCo composites [37].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. 2. \u0026nbsp;FTIR analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe FTIR spectra of the PC, PCCo-0.2, and PCCo-0.4 composites are shown in Fig. 2. It is observed that the characteristic peaks are at 3734, 2338.2, 1692.2, and 1527.2 cm\u003csup\u003e-1\u003c/sup\u003e. The band at 3734 cm\u003csup\u003e-1\u003c/sup\u003e is assigned to the stretching vibration of the O-H mode of the hydroxyl functional group [38]. The peak observed at 2338.2 cm\u003csup\u003e-1\u003c/sup\u003e is assigned to the CO\u003csub\u003e2\u003c/sub\u003e molecules as a result of the interaction of porous carbon and composites with CO\u003csub\u003e2\u003c/sub\u003e molecules from the atmosphere [39], and at 1692.2 \u0026nbsp;cm\u003csup\u003e-1\u003c/sup\u003e it is attributed to the stretching vibration of the C=O bond [40]. The band at 1527.2 cm\u003csup\u003e-1\u003c/sup\u003e is attributed to C=C aromatic stretching vibration [35]. Additionally, a new peak was found at 730 cm\u003csup\u003e-1\u003c/sup\u003e in PCCo-0.2 in relation to the vibrations of cobalt oxide bonds [41]. In this perspective, new peaks at 683.4 and 565 cm\u003csup\u003e-1\u003c/sup\u003e for PCCo-0.4 indicate composite influence associated with vibrations of cobalt oxide bonds [42]. The existing functional groups have a substantial impact on the hydrophilicity of the carbon surface, which is a crucial component in increasing specific capacitance. The FTIR results confirm the presence of C, O, and Co elements in the PCCo-0.4 composite, which is agreement with the analysis of elemental mappings.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. 3. FESEM image analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFESEM images provide the morphology and microstructural arrangement of PC, PCCo-0.2, and PCCo-0.4 composites, as shown in Fig. 3. Fig. 3(a) demonstrated roughness and interconnected pores with hierarchical-like morphologies on the surface for PC, which is a material advantage to insert more ions into existing pores should the volume to surface charge ratio change, which may improve the electrochemical performance of the device [43, 44]. Fig. 3(b) reveals that the irregular porous structure should facilitate the contact of more active sites, which may help to easily diffuse the charges during the electrochemical mechanism through electrolytes in the case of the PCCo-0.2 composite. Moreover, the interconnected porous networks became non-existent and were replaced by exposed large pores in PCCo-0.2. This was due to the incorporation of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles during the carbonization process. It is also interpreted that it boosts ion transport and increases the density of the active centre [9]. PCCo-0.4 is depicted in Fig. 3(c), which reveals that the activated carbon possesses a rough porous structure with large open channels and the Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles dispersed onto the porous carbon surface. The existence of open channels forms porous carbon, which allows ions to access a larger surface and a route track for transport during the charge storage process [10]. Additionally, elemental mapping has also been carried out to confirm the presence of various elements in the PCCo composite, as depicted in Fig. 3(e-f). The EDS results revealed the presence of Co, O, and C elements in the PCCo composite. \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. 4. HR-TEM image analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHR-TEM analysis was carried out to determine the dispersion of cobalt oxide nanoparticles on the activated porous carbon surface, as shown in Fig. 4(a \u0026amp; b). It is also seen that contrasts of dark and light morphology correspond to the porous structure and the pore channels, respectively [45]. The HR-TEM image of PCCo-0.4 shows that the Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles are well-integrated in the porous carbon matrix in Fig. 4 (c). For Fig. 4(d), the lengths of cobalt oxide particles are 326.94, 297.09, and 164.94 nm. Fig. 5(e), which displays the HR-TEM image of PC with an apparent spacing of 0.34 nm, reflects the (002) lattice plane of graphite carbon [46]. The SAED Fig. 4(g) inset represents the (002) plane of graphite carbon from the inside out. The HR-TEM image of the PCCo-0.4 composite is as shown in Fig. 4 (f). It is seen that the lattice fringes of the black nanoparticles were calculated to be around 0.24 and 0.20 nm, which correspond to the (311) and (400) planes of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, respectively [47, 48]. In addition, it is also seen that the presence of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e is shown by the selected-area electron diffraction (SAED) patterns cited in figure 4 (h), which agree with the results of the XRD investigation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.5. Raman spectroscopy analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Raman spectra of the PC, PCCo-0.2, and PCCo-0.4\u0026nbsp;composites between 500 and 3000 cm\u003csup\u003e-1\u003c/sup\u003e in wavelength are displayed in Fig. 5. It is observed that the two peaks \u003cstrong\u003eD\u003c/strong\u003e band (at 1370 cm\u003csup\u003e-1\u003c/sup\u003e) and \u003cstrong\u003eG\u003c/strong\u003e band (at 1590 cm\u003csup\u003e-1\u003c/sup\u003e) are linked to the presence of dis-orders caused by the sp\u003csup\u003e3\u003c/sup\u003e carbon configuration and the in-plane bond-stretching mode of the sp\u003csup\u003e2\u003c/sup\u003e carbon configuration, respectively [49, 50]. By comparing the intensity of the two bands (I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e), it is usually possible to identify defects in the surface structure of carbon materials [51].\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e values for the PCCo-0.4 (0.720) and PCCo-0.2 (0.692) composites were higher than those for pure PC (0.660). An increase in the intensity ratio of I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u0026nbsp;\u003c/sub\u003eindicates a decrease in the dimensions of the sp\u003csup\u003e2\u003c/sup\u003e domains within the plane and a structurally organized crystalline pattern of PCCo-0.2 and PCCo-0.4 composites. This suggests the presence of imperfections caused by the incorporation of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles into porous carbon, resulting in the formation of voids within the porous carbon structure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6. Electrochemical performance\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6.1 Cyclic Voltammetry\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCyclic voltammetry was used to investigate the electrochemical performance of electrodes, as shown in Fig. 6, and the data was used to estimate the specific capacitance of the samples at various scan rate values.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eCV study was carried out in a 3M KOH aqueous electrolyte medium with a potential window ranging from -0.6 V to +0.6 V and scan rates ranging from 10 mV/s to 50 mV/s for PC, PCCo-0.2, and PCCo-0.4 composites. Fig. 6(a, b, \u0026amp; c) show the height of the peak currents increases with scan rate and a gradual shift towards a higher potential value (oxidation process), whereas a shift to a lower potential was noticed (reduction process). As the scan rate increases, the charging current increases, indicating that more current is allowed to flow. The equation is used to determine specific capacitance;\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003eWhere Csp is the specific capacitance, I is the current\u003cem\u003e,\u0026nbsp;\u003c/em\u003e∆𝑉\u0026nbsp;is the potential window, and \u0026lsquo;\u003cem\u003em\u0026rsquo;\u0026nbsp;\u003c/em\u003eis the mass of the active material.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe estimated specific capacitance value for the PC sample is 207 F/g at a scan rate of 10 mV/s; the PCCo-0.2 and PCCo-0.4 composites showed specific capacitance values of 321 and 548.4 F/g, respectively. The cyclic voltammograms show typical redox rectangle forms with anodic and cathodic peaks, clearly indicating the pseudocapacitive behavior of the material [52]. Fig. 6(d) also illustrates that the PCCo-0.4 composite exhibits a significantly larger capacitance than the PC and PCCo-0.2 composites. The specific capacitance of the activated carbon has consequently been improved by the addition of Co, as could be safely asserted. Additionally, the use of aqueous KOH as the electrolyte rather than inorganic ones, considering that the latter offers a larger ionic concentration and lower resistance, may have high power and capacitance [53].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6.2 Galvanostatic Charging-Discharging\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe GCD analysis of PC, PCCo-0.2, and PCCo-0.4 composite electrodes was conducted at multiple current densities varying between 1.5 and 2.25 A/g with a voltage window ranging from -0.6 to +0.6 V. The GCD curve shows a symmetric triangular shape, which indicates the pseudocapacitance behavior. The discharge time gets increased with the decrease in the CD, which is due to the limitation of charge transport diffusion coefficients at higher current densities [54].\u0026nbsp;Which are diffusion-controlled processes as well as having great reversibility.\u003c/p\u003e\n\u003cp\u003eThe formula used to determine the specific capacitance from the GCD data is the below equation;\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003eWhere Csp is the specific capacitance, I is the current, ∆𝑡 is the discharge time, ∆𝑉 is the potential\u0026nbsp;\u003cbr\u003eWindow, and \u003cem\u003em\u0026nbsp;\u003c/em\u003eis the mass of the active material. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The specific capacitances from the discharge curves are 375 F/g (PC), 515.4 F/g (PCCo-0.2), and 696.8 F/g (PCCo-0.4) at a current density of 1.5 A/g in 3M KOH electrolyte, as shown in Fig. 7(a, b \u0026amp; c). Furthermore, compared with other values, the specific capacitance of PCCo-0.4 is significantly better than that of some cobalt-based materials like PC and PCCo-0.2, as revealed in Fig. 7(d). It can be concluded that ion diffusion and electron transport play important roles in the performance of supercapacitor [55]. Commonly, it is believed that materials with porous structures should be better for energy storage due to the high surface area and the channels for fast ion diffusion [56].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6.3\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eElectrochemical Impedance Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe EIS spectra are used to study the exact electrical conductivity of poroused\u0026nbsp;PC, PCCo-0.2, and PCCo-0.4\u0026nbsp;electrode material at room temperature in the frequency range 1\u0026ndash;10\u003csup\u003e5\u003c/sup\u003e Hz. In general, the impedance curves present two partially overlapped semicircles in the high and medium frequency regions and an inclined line in the low frequency region [57]. It is obvious that the diameters of the semicircles for PC and PCCo-0.2 are larger than those for PCCo-0.4, indicating that the hybrid samples possess much lower charge transfer resistance [26, 58], which is confirmed by the inset figure fitting results as illustrated in Fig. 8(a). According to the results, the Rct of PC and PCCo-0.2 is 4.2, and 3.7 \u0026Omega;, much higher than that of PCCo-0.4 (1.2 \u0026Omega;). In this investigation, the sole disparity in the electrodes lies in the composite matrix of cobalt oxide and the resultant morphology. Therefore, the variations in impedance among the five electrodes manifest the influences of the cobalt oxide. This discernment can be attributed to the morphology and arrangement of the cobalt oxide in the porous carbon structure. It is observed that the PCCo-0.4 electrode SCs device has a high energy density (ED) of 47.4 Whkg\u003csup\u003e-1\u003c/sup\u003e at a power density (PD) of 853.2 Wkg\u003csup\u003e-1\u003c/sup\u003e and decreases to 18.8 Whkg\u003csup\u003e-1\u003c/sup\u003e at a maximum PD of 1358.2 Wkg\u003csup\u003e-1\u003c/sup\u003e, as shown by the Ragone plot in Fig. 8(b). This value is higher or comparable to other porous carbon/cobalt oxide composites for SCs reported recently, such as BIC-Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (17 Wh kg\u003csup\u003e-1\u003c/sup\u003e, 184 W kg\u003csup\u003e-1\u003c/sup\u003e)\u0026nbsp;[59], Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@NOPC-200 (42.5 Wh kg\u003csup\u003e-1\u003c/sup\u003e, 746 W kg\u003csup\u003e-1\u003c/sup\u003e)\u0026nbsp;[60],\u0026nbsp;Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@MBC/NF (19.74 Wh kg\u003csup\u003e-1\u003c/sup\u003e, 560 W kg\u003csup\u003e-1\u003c/sup\u003e)\u0026nbsp;[47], (3DPC)/Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (21.1 Wh kg\u003csup\u003e-1\u003c/sup\u003e, 790 W kg\u003csup\u003e-1\u003c/sup\u003e)\u0026nbsp;[61], Ni-Co-S@N-pCNFs (21.6 Wh kg\u003csup\u003e-1\u003c/sup\u003e, 134.9 W kg\u003csup\u003e-1\u003c/sup\u003e) [62], as shown in Table (2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable. 2: Comparison of performance of this work with recent work on porous carbon and cobalt oxide composites\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn addition, the GCD analysis is to investigate the reliability of the SCs electrode materials, and it was noticed that PCCo-0.4 exhibits long stability cycling and more energy storage systems. The capacitance retention of the PCCo-0.4 electrode is still 84.4%, as shown in Fig. 8(c). The supercapacitor\u0026apos;s coulombic efficiency (\u0026eta;) was calculated using the following equation; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003eWhere \u0026Delta;td and \u0026Delta;tc represent the discharge and charge times, respectively.\u003c/p\u003e\n\u003cp\u003eThere is no apparent IR drop, and all curves are linear and symmetrical, even after showing 5000 cycles at a CD of 1 A/g. The proposed electrode material can be attributed to the electrode matrix\u0026apos;s insignificant loss during the charging-discharging cycle [63, 64].\u0026nbsp;\u003c/p\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn conclusion, we successfully used a facile one-step carbonization and activation process to synthesize activated porous carbon derived from date seeds and cobalt oxide composites. The resulting PCCo revealed a highly porous microstructure with an improvement in crystallinity owing to the Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e particles\u0026rsquo; catalytic graphitization, which helped to convert some of the amorphous carbon into more ordered graphite. The PCCo-0.4 electrode supercapacitor devices showed a high specific capacitance, extended lifetime, and low outflow current. The GCD values in the PCCo-0.4 electrode have a high capacitance of 671 F/g at a current density of 1.5 A/g. At a scan rate of 10 mV/s, the CV capacitance is 496 F/g. The SSC PCCo-0.4//PCCo-0.4 device exhibited an energy density of 47.4 Wh kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and a power density of 853.2 W kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with capacitance retention of 84.4% and coulombic efficiency of 97% even after 5000 cycles of charging and discharging at 1 A/g. In addition to a cost-effective and technologically unique method for using environmental supercapacitor applications, this study also presented a novel carbon source that is inexpensive, easy to use, and favorable to the environment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eCompliance with ethical standards\u003c/h2\u003e \u003cp\u003eConflict of authors interest declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAbdullah Ba shbil- work carried out \u0026amp; prepare this manuscriptNagaraju Y S- Support to literature review Ganesha H-Synthesis of methodsVeeresh S-CharacterizationSuresh D S-Electrode fabrication \u0026amp; experimental measurementVijaykumar S P- plot graphSapna Sharanappa-Analysis Devendrappa H - Superivisor\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eArticle is prepare by own without external\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eS. 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Liu \u003cem\u003eet al.\u003c/em\u003e, \u0026ldquo;Electrodeposition of Ni-Co-S nanosheet arrays on N-doped porous carbon nanofibers for flexible asymmetric supercapacitors,\u0026rdquo; \u003cem\u003eJ. Alloys Compd.\u003c/em\u003e, vol. 762, pp. 301\u0026ndash;311, 2018, doi: 10.1016/j.jallcom.2018.05.239.\u003c/li\u003e\n \u003cli\u003eJ. Liu \u003cem\u003eet al.\u003c/em\u003e, \u0026ldquo;Three-dimensional hierarchical and interconnected honeycomb-like porous carbon derived from pomelo peel for high performance supercapacitors,\u0026rdquo; \u003cem\u003eJ. Solid State Chem.\u003c/em\u003e, vol. 257, no. July, pp. 64\u0026ndash;71, 2018, doi: 10.1016/j.jssc.2017.07.033.\u003c/li\u003e\n \u003cli\u003eY. Gao \u003cem\u003eet al.\u003c/em\u003e, \u0026ldquo;Chemical activation of carbon nano-onions for high-rate supercapacitor electrodes,\u0026rdquo; \u003cem\u003eCarbon N. Y.\u003c/em\u003e, vol. 51, no. 1, pp. 52\u0026ndash;58, 2013, doi: 10.1016/j.carbon.2012.08.009.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"porous carbon composite, specific capacitance, high energy density, cycle stability","lastPublishedDoi":"10.21203/rs.3.rs-5236326/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5236326/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA new strategy made to have a low-cost highly porous carbon electrode material by using bio-waste date seeds is activated with potassium hydroxide (KOH) for the synthesis of porous carbon cobalt oxide composite (PCCo) by facile one-step carbonization, and achieved high specific capacitance. The characterization of PCCo composite was done by powder X-ray diffraction, Fourier transform infrared spectrometer, field emission scanning electron microscopy, high-resolution transmission microscopy, and Raman spectroscopy techniques to confirm the changes in the chemical formation of the composite. The obtained PCCo composite has a porous structure with carbon frameworks and uniformly dispersed Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles. This hierarchical architecture offers good ion/electron transport channels for better electrochemical characteristics.The maximum specific capacitance was found to be 548.4 F/g at\u0026nbsp; a scan rate of 10 mV/s, and also from the galvanostatic charge-discharge curve, it was 696.8 F/g at a current density of 1.5 A/g. Additionally, capacitance retention is 84.4% and coulombic efficiency is 97% even after 5000 cycles. The energy density is 47.4 Wh kg\u003csup\u003e-1\u003c/sup\u003e and the power density is 853.2 W kg\u003csup\u003e-1\u003c/sup\u003e. These results suggest that porous carbon composites are cost-effective, technologically unique, and eco-friendly for environmental supercapacitor applications.\u003c/p\u003e","manuscriptTitle":"Facile synthesis of hierarchical morphology highly porous carbon cobalt oxide composite from one-step carbonization of bio-waste for energy storage application","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-09 13:35:31","doi":"10.21203/rs.3.rs-5236326/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-11-04T16:53:59+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-01T12:06:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-29T02:51:30+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-25T15:51:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"335104493754840739950906805734878863280","date":"2024-10-24T07:30:48+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-23T05:39:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"53430622004766218451036526283804013779","date":"2024-10-21T12:29:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"25897987234912573931900375878695201515","date":"2024-10-21T06:50:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"100005071093390750675711725536759217986","date":"2024-10-21T00:45:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"99460234578421400759035820373856230233","date":"2024-10-18T23:23:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-10-18T18:31:05+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-10-11T04:07:00+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-10-11T03:10:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Ionics","date":"2024-10-10T04:22:10+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"cde0addc-5a7f-4500-a210-64023503bf4d","owner":[],"postedDate":"December 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-01-06T21:23:07+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-09 13:35:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5236326","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5236326","identity":"rs-5236326","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}