Design of Flexible and Green Chemistry Synthesis Method for Highly Crystalline COFs for Supercapacitor Applications 

Design of Flexible and Green Chemistry Synthesis Method for Highly Crystalline COFs for Supercapacitor Applications | 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 Design of Flexible and Green Chemistry Synthesis Method for Highly Crystalline COFs for Supercapacitor Applications Shanxin Xiong, Ke Fang, Kerui Zhang, Jingru Guo, Min Chen, Juan Wu, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4487665/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract Covalent organic frameworks (COFs) have attracted much attention in energy storage due to their porous network structure, large specific surface area, high crystallinity, and pseudocapacitive ability brought by redox reactions. However, the traditional synthesis method of COFs involves toxic solvents and requires high temperatures and pressure. Therefore, it is necessary to develop simple synthesis methods for large-scale practical application of COFs. This study investigated the synthesis and electrochemical properties of two kinds of COFs, which were synthesized through the reflux heating method and solvothermal method using Tri(4-aminophenyl)amine (TAPA) and tris(benzaldehyde) (TFB) as monomers. The results show that COFs synthesized by reflux heating (Re-COF-TAFB) outperforms COFs Synthesized by solvothermal method (So-COF-TAFB) in specific surface area, thermal stability, and electrochemical properties. Re-COF-TAFB has a specific capacitance of 248 F·g − 1 at 0.1 A·g − 1 and a capacitance retention rate of 104.13% after 10,000 charge and discharge cycles. This paper contributes to understanding COFs' synthesis methods and their impact on material properties. Reflux heating is highlighted as an efficient technique for developing high-performance COF-based supercapacitors. Covalent Organic Frameworks Reflux Heating Method Solvothermal Synthesis Supercapacitors Electrochemical Properties Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Due to the continuous deterioration of the environment caused by greenhouse effect, the demand for energy sources that do not emit greenhouse gases is constantly increasing[ 1 ]. Therefore, we urgently need a method to collect and store energy efficiently. Supercapacitors have received widespread attention due to their high power density, long lifespan[ 2 ], and fast charging and discharging speed[ 3 – 4 ]. The energy storage process in supercapacitors involves two main mechanisms. First one is Electric double layer capacitor (EDLC), which stores energy by forming positive and negative charge layers at the electrolyte/electrode interface[ 5 ]. Second one is pseudocapacitive mechanism, which relies on reversible redox reactions for energy storage[ 6 – 7 ]. The working mechanisms of these supercapacitors exhibit significant differences[ 8 ]. The electrode material plays a crucial role in the electrochemical performance of supercapacitors, so it is necessary to develop suitable electrode materials[ 9 ]. Some carbon-related materials, such as carbon nanotubes, graphene[ 10 ] and porous carbon[ 11 ], are frequently used in EDLC[ 12 ]. Transition metal oxides are the most classic pseudocapacitive electrode materials, but new materials such as covalent organic frameworks(COFs)[ 13 ], perovskites[ 14 ], chalcogenides[ 15 ], and MXenes[ 16 ] have also shown tremendous potential in the application of pseudocapacitive electrodes[ 6 ]. COFs are crystalline organic polymers[ 17 – 18 ] with ordered pores and periodic frameworks, primarily composed of light elements[ 19 ] and synthesized through reversible condensation reactions to form stable structures due to dynamic covalent chemistry[ 20 ]. Conjugated layer structure can provide nanoscale stacked channels for ion transport, improving electrochemical performance[ 21 ].COFs can be prepared through various reactions, such as diazonium coupling, triazine formation[ 22 ], and imine condensation[ 23 ]. The redox activity of COFs mainly relies on the reversible reactions of the building block. The formation of imine bonds through Schiff base reaction is a typical example[ 7 , 17 ] to synthesize COFs. Common methods for preparing COFs include solvothermal synthesis, mechanochemical synthesis, solvent-free method[ 24 ], and plasma-induced synthesis, etc[ 25 ]. Since the emergence of COFs materials in 2005, for a long time, COFs' synthesis has mainly been carried out using solvothermal method[ 24 , 26 – 27 ], often requiring high-temperature degassing and sealing treatments. However, this method often requires high temperature and high pressure conditions[ 25 ], as well as the use of organic solvents with high boiling points and toxcity[ 28 ]. Due to the potential safety issues caused by harsh conditions, mild synthetic methods may be considered to prepare COFs, such as mechanochemical and reflux heating methods. Mechanochemical synthesis was once considered a promising alternative to solvothermal method for synthesizing COFs[ 29 ]. Bishnu P. Biswal et al[ 30 ], successfully synthesized three COFs with excellent chemical stability using a mechanochemical synthesis method at room temperature. However, this method results in lower crystallinity and limited control over morphology during the synthesis process[ 31 ]. To overcome the limitations of traditional methods, the heating reflux method can be considered for the synthesis of COFs, which combines the advantages of the solvothermal and mechanical ball milling methods, creating COFs under mild conditions without needing high-boiling-point solvents. Wang et al[ 32 ], have successfully developed a simple solution reflux synthesis method in their study. The COF-300 synthesized using this method exhibits excellent crystallinity and high porosity, effectively enhancing the synthesis efficiency and performance of covalent organic framework materials. By adjusting the heating temperature and time, the pore structure and molecular arrangement of COFs can be precisely controlled, creating high-performance COFs materials. Therefore, exploring the synthesis methods of COFs is of great significance for achieving safety, reliability, environmental friendliness, and large-scale production. Our research aims to contribute to a more sustainable practice in the electrochemistry field based on the challenges discussed earlier in COFs synthesis, particularly the safety issues associated with solvothermal method. Recognizing the need for safe synthesis of COFs materials, we have shifted our focus to innovative synthesis technologies that can improve safety while reduce the ecological impact. In this study, COF-TAFB was synthesized by reflux heating and solvothermal method using ethanol as solvent, and tri (4-aminophenyl) amine (TAPA) and trimesic acid (TFB) as building units. Compared with the solvothermal method, the heating reflux method has the advantages of mild synthesis conditions, high safety, simple operation and scalability. Herein, the comparative study was carried out through investigating the structural and performance difference of Re-COF-TAFB and So-COF-TAFB induced by different synthesis methods. 2. Experimental 2.1 Materials Tri(4-aminophenyl)amine (TAPA) and tris(benzaldehyde) (TFB) were purchased from Shanghai Kylpharm Co., Ltd, China. Ethanol (EtOH) was purchased from Tianjin Kemiou Chemical Reagent Co., Ltd, China. N, N-Dimethylformamide (DMF) was purchased from Tianjin Fuyu Chemical Co., Ltd, China. Conductive carbon black was purchased from Timcal Co., Ltd, Switzerland. Polyvinylidene fluoride (PVDF) was purchased from Suzhou Yilongsheng Energy Technology Co., Ltd, China. All chemicals were used without further purification. 2.2 Synthesis of So-COF-TAFB and Re-COF-TAFB The synthesis of So-COF-TAFB was executed using the following steps: TAPA (0.08711 g, 0.3 mmol) and TFB (0.04864 g, 0.3 mmol) were mixed in 15 mL of EtOH (99.7% purity). The mixture was subjected to ultrasonic agitation for 30 min until complete dissolution of the monomers. The clear solution was transferred into a Teflon reactor and heated at 85°C for different hours. After cooling, the reaction mixture was transferred into centrifuge tubes and washed with DMF until the supernatant was colorless. Subsequent washings with anhydrous ethanol were performed three to five times to remove residual DMF. The product was dried at 60°C for 24 hours in a vacuum oven. Finally, the dry product was ground using an agate mortar to yield red So-COF-TAFB powder. The following procedure prepares Re-COF-TAFB: Transfer the same monomer solution to a three-necked flask, purged with nitrogen gas and sealed before the assembly of the reflux apparatus. The setup was placed in an oil bath for the various reaction time at 85°C. After the reaction, the product was cooled and washed with DMF until the supernatant became colorless, followed by three to five washes with anhydrous ethanol. Subsequently, the material was dried at 60°C for 24 hours in a vacuum oven. Finally, the dried product was ground in an agate mortar to obtain red Re-COF-TAFB powder. Scheme.1 shows the schematic diagram of the synthesis process of COF-TAFB. 2.3 Preparation of electrodes with So-COF-TAFB and Re-COF-TAFB active materials The electrode material was prepared by mixing So-COF-TAFB powder, conductive carbon black, and PVDF in a mass ratio of 6:3:1. The mixture was ground certain amount of with DMF in an agate mortar to obtain even paste. The paste was then ultrasonicated for 30 min in an ultrasonic cleaner to achieve a uniformly dispersed slurry. The slurry was evenly spread over a 1×4 cm 2 carbon paper substrate with the target coating area about 1×1 cm 2 . The coated substrate was then dried in a vacuum oven at 60°C for 12 hours, resulting in a final material loading of approximately 0.7 to 1 mg/cm 2 . The procedure for preparing the electrode material of Re-COF-TAFB was identical to the process utilized in the fabrication of So-COF-TAFB. 2.4 Characterizations Phenom/Pro scanning electron microscope (SEM) was used to observe the microstructure of So-COF-TAFB and Re-COF-TAFB. Perkin-Elmer FT-IR spectrometer was employed to acquire the samples' Fourier-transform infrared (FTIR) spectra within the 40-4000 cm − 1 range by the KBr method. The Raman spectra (Raman) were collected using a Renishaw inVia reflectance confocal micro-Raman spectrometer equipped with a 785 nm laser source. Thermogravimetric analysis (TGA) was performed on a Setaram Labsys Evo TG-DSC integrated thermal analyzer from France, measuring under a nitrogen atmosphere with a 5°C/min heating rate from 50°C to 800°C. The crystal structure of the samples was examined using a German Bruker D8A25 instrument (PXRD, Cu Kα radiation, λ = 1.5418 Å), with a scan range of 2θ = 2 to 50°. The Brunauer–Emmett–Teller (BET) specific surface area and pore structure characteristics were measured using a Micromeritics ASAP 2020 specific surface area analyzer through N 2 adsorption-desorption measurements at 77 K. Cyclic voltammetry (CV) tests were conducted using a CHI660E electrochemical workstation in a 1 M H 2 SO 4 electrolyte. The scan rates were 10, 20, 50, 75, and 100 mV s − 1 . For Galvanostatic charge-discharge (GCD) tests, the current densities were varied at 0.1, 0.2, 0.5, 1, 2, and 5 A·g − 1 . Electrochemical impedance spectroscopy (EIS) measurements were performed over a frequency range of 0.01 Hz to 10 5 Hz. The specific capacitance of the material from the GCD curves can be estimated using the formula (1) below: $$\begin{array}{c}C=\frac{{I\varDelta t}_{d}}{m\varDelta V} \left(\text{1}\right)\end{array}$$ In the above formula, C (F · g − 1 ) represents the specific capacitance of the material, I (A) is the discharge current , \({\varDelta t}_{d}\) (s) is the discharge time, m (g) is the mass of active material on the collector, and \(\varDelta V\) (V) is the potential window of electrode materials. 3. Results and discussion 3.1 The microstructure of So-COF-TAFB and Re-COF-TAFB As depicted in Fig.1, the effects of varying reaction durations on the microstructure of COFs were investigated. Figs.1 (a, b, c) and (d, e, f) showcase the microstructures of So-COF-TAFB and Re-COF-TAFB at reaction time of 2 hours, 3 hours, and 4 hours, respectively. It can be observed that the reaction time plays a crucial role in determining the product morphology. If the reaction time is set to 2 hours, the monomer does not get enough time to react, resulting in uneven morphology and particle size. When the reaction time is increased to 3 hours, a highly ordered and uniform sphere structure is formed due to the dynamic equilibrium reached by the crystal growth and aggregation process. However, if the reaction time is increased to 4 hours, the overreacted crystals may start aggregating into larger particles, leading to irregular microscopic morphology. When the reaction time is set to 3 h, there is a significant difference in particle size between So-COF-TAFB (Fig.1(b)) and Re-COF-TAFB (Fig.1(e)). The average particle size of So-COF-TAFB and Re-COF-TAFB are 1.706 μm and 0.511 μm, respectively. The oversized particle size of So-COF-TAFB will reduce specific surface area. Therefore, it will affect the electrochemical performance of COF-TAFB. It's noteworthy that uniform microstructure in materials can substantially enhance the performance of supercapacitors. This uniformity ensures more consistent electrochemical properties and can lead to improved energy storage efficiency. To comprehensively understand the impact of different synthesis methods, we also employed additional characterization techniques to elucidate further the relationship between microstructure and the overall properties of COFs. 3.2 Structure Characterization of So-COF-TAFB and Re-COF-TAFB FT-IR spectroscopy can prove the successful synthesis of So-COF-TAFB and Re-COF-TAFB. As shown in Fig.2 (a), So-COF-TAFB and Re-COF-TAFB both exhibit characteristic peaks of Schiff base -C=N- stretching vibrations at positions of 1621 cm -1 and 1634 cm -1 , while the distinct peaks of -NH 2 at 3409 cm -1 and 3338 cm -1 for TAPA, as well as the characteristic peak of -CHO at 1648 cm -1 for TFB, almost disappear. It indicates that the -C=N- bond is generated during the synthesis process through the Schiff base reaction. Through the Raman spectra (Fig.2 (b)) of the samples, it can be further observed that the -C=N- bond at 1586 cm -1 and 1587 cm -1 are formed during the synthesis process, while the -C=O- bond at 1434 cm -1 and 1428 cm -1 , as well as the -N-H- bond at 1354 cm -1 and 1355 cm -1 are disappeared. This provides further evidence for the successful synthesis of So-COF-TAFB and Re-COF-TAFB. In this study, we conducted a detailed analysis of the material's crystal structure using PXRD techniques. Fig.2 (c) displays the PXRD pattern of COF-TAFB and AA Stacking Model, where peaks at 4.83°, 9.42°,11.1°, and 25.03°, corresponding to the (100), (110), (200), and (001) crystal planes of COFs, respectively. The high intensity of the (100) peak suggests a well-defined periodic structure in the material. And the characteristics of the (001) plane suggest a vertical stacking nature of the material, which could influence its porous structure. This feature is likely to significantly enhance the ion diffusion rate and energy storage efficiency in electrochemical energy storage devices. From the PXRD characteristic peaks of Re-COF-TAFB (Fig.2 (c)), we can see that the (100) crystal plane (4.83°) and (001) crystal plane (25.03°) are distributed in the graph. However, the PXRD pattern of So-COF-TAFB(Fig.2 (c)) show that except for the 100 crystal plane, the rest of the crystal planes do not show strong expression, so we judge that the crystallinity of Re-COF-TAFB is more excellent than that of So-COF-TAFB. the weakness of the (001) plane indicates that AA stacking is short in the crystal material, which leads to instability in the channel structure, potentially further limits ion diffusion and energy storage efficiency. It is not difficult to discern through comparison that, although So-COF-TAFB possesses a good periodic structure, Re-COF-TAFB exhibits a more stable AA stacking structure. The stable AA stacking structure of Re-COF-TAFB is conducive to further accelerating the transfer of ions and charges in the electrolyte, endowing the material with superior electrochemical properties. The PXRD results for Re-COF-TAFB were refined using the Pawley method, yielding lattice parameters a = b = 16.6722 Å, c = 3.4051 Å, with α = β = 90°, and γ = 120°. The refined result with Rwp=10% and Rp=6.99%. The degree of fit between the refined PXRD patterns and experimental data was evaluated using a difference plot. As depicted in Fig.2d, the refined PXRD pattern closely matches the experimentally obtained PXRD pattern. The PXRD results confirmed that Re-COF-TAFB possesses an AA stacking, long-range ordered porous structure. As shown in Fig.3 (a), we can see that the adsorption and desorption curves of So-COF-TAFB are roughly similar, but the specific surface area of So-COF-TAFB is only 110.2 m 2 ·g -1 . In Fig.3 (b), the specific surface area analysis of Re-COF-TAFB material. The adsorption and desorption curves of Re-COF-TAFB can be seen to have a peak at P/P 0 =1, and there is a bulge in the low P/P0 region, which belongs to type IV isotherm, there is a desorption hysteresis between the two curves. This indicates that Re-COF-TAFB may have a porous structure[33]. According to the pore size distribution curve of Re-COF-TAFB(Inset of Fig.3 (a)), it can be observed that its pore size distribution is mainly concentrated in the mesoporous range (2-50 nm). Through calculating, the specific surface area of Re-COF-TAFB was determined to be 143.96 m 2 ·g -1 . Compared to the solvothermal method, Re-COF-TAFB prepared by the reflux heating method has a higher specific surface area. This is consistent with the previous SEM test results. A larger specific surface area has a positive impact on improving the electrochemical performance of supercapacitors. The thermal stability of porous materials is a significant performance index. It is observable that both So-COF-TAFB and Re-COF-TAFB exhibit a weight loss of less than 7% before 450 °C. This indicates that these materials possess excellent thermal stability. Moreover, it is not difficult to see that Re-COF-TAFB exhibits better thermal stability, having lost 45.08% of its weight throughout the entire thermal stability test, compared to the 48.49% weight loss of So-COF-TAFB. Excellent thermal stability indicates that the material is not easily degraded under high temperature conditions, which can effectively prolong the service life of supercapacitors. 3.3 Electrochemical properties of So-COF-TAFB and Re-COF-TAFB To investigate the differences in electrochemical performance of COFs materials synthesized by two different methods, CV, GCD, and EIS electrochemical analysis methods were used to analyze and test the prepared electrodes. The CV results of the electrode material indicate that within the scanning rate range of 10-100 mV·s -1 , the shape of the test curve remains relatively stable and exhibits certain symmetry. This indicates that the assembled supercapacitor possesses electrochemical activity and reversibility. Compared to So-COF-TAFB(Fig.4 (a)), the CV curves of Re-COF-TAFB(Fig.4 (b)) tends towards a more "rectangular" shape, suggesting that Re-COF-TAFB material may possess superior double-layer capacitance characteristics. The presence of oxidation-reduction peaks in the curve also indicates the pseudocapacitive properties of the material. The CV curves of Re-COF-TAFB enclose a larger area, implying that Re-COF-TAFB has a higher specific capacitance. This corresponds to the previous SEM and BET test results, where the uniform morphology and larger surface area are more conducive to exhibiting excellent electrochemical performance. Fig.4 (d) shows the GCD curves of Re-COF-TAFB, which has an approximate "triangular" shape with a charging plateau in the middle. As the current density increases, there is no significant change in the shape of the curve, the capacitance decreases from 248 F·g -1 (0.1 A·g -1 ) to 151 F·g -1 (5 A·g -1 ). The GCD test results of So-COF-TAFB are shown in Fig.4 (c), the capacitance decreased from 232 F·g -1 (0.1 A·g -1 ) to 142 F·g -1 (5 A·g -1 ). Through GCD curves, we can calculate that with the increase of current density, the capacitance retention rate of Re-COF-TAFB (Inset of Fig.4 (d)) decreases little and keeps above 60% all the time. Through impedance analysis of EIS, the electrochemical characteristics of Re-COF-TAFB and So-COF-TAFB were further analyzed. As shown in Fig.5, the Nyquist plots of So-COF-TAFB and Re-COF-TAFB (Fig.5 (a) and (b)) in the frequency range from 0.01 to 10 5 Hz are depicted. The plots demonstrate low interfacial impedance and good gap conductivity[34]. It can be observed that nearly vertical lines are present in the low-frequency region, indicating their excellent capacitive properties. Combined with the previous CV and GCD results, it can be found that the electrochemical performance of Re-COF-TAFB is better than So-COF-TAFB as a whole. The cyclic stability tests of So-COF-TAFB and Re-COF-TAFB (Fig.5 (c) and (d)), showing that their capacitance retention rates after 10,000 cycles were 102.58% and104.13%, respectively. It can be observed that their capacitance retention rates are all greater than 100%. This result ranks among the top in the published research reports, as shown in Table 1. We speculate that this is due to the insufficient contact between the electrode and electrolyte when the electrode enters the electrolyte, resulting in an incomplete manifestation of electrochemical performance. As the number of cycles increases, the contact between the electrode and electrolyte becomes more sufficient. After a long period of charge-discharge, there is a specific pore expansion effect in the electrode material, which leads to an increasing trend in capacitance retention rate[35]. With the increase in the number of cycles, the Coulomb efficiency of Re-COF-TAFB and So-COF-TAFB remains unchanged. This is due to the excellent thermal and structural stability of COF-TAFB. Furthermore, test results indicate that So-COF-TAFB exhibits a slightly lower capacitance retention rate than Re-COF-TAFB. Overall, comparing reflux heating and solvent thermal methods for synthesizing the same COFs under identical conditions, the product from reflux heating exhibits superior electrochemical performance due to its more uniform microscopic morphology, smaller particle size, and larger specific surface area. Additionally, the reflux heating method offers a simpler and milder synthesis process, avoiding the high temperature and pressure associated with traditional solvent thermal methods. This not only enhances the environmental friendliness of the approach but also holds promise for facilitating easier and more efficient synthesis in the future. Table.1 Review of COFs Synthesized by Different Methods for Supercapacitor Electrode materials Reaction medium and Reaction time Synthesis method Retention (%)(cycle@current density (A/g)) Ref TpPa-COF@PANI Reaction in mesitylene, 1, 4-dioxane, acetic acid for 3 days; Solvothermal method 83%( [email protected] A·g -1 ) [36] BTT-DADP COF-700 Reaction in ZnCl 2 for 20h; Ionothermal synthesis 77.5%(10000@10 A·g -1 ) [37] TpOMe-DAQ Reaction in 2M/3M H 2 SO 4 Mechano-chemical grinding 65%(50000@5 mA·cm -1 ) [38] TaPa-Py COF Reaction in mesitylene, 1, 4-dioxane, acetic acid for 3 days;- Solvothermal method 92%(6000@2 A·g -1 ) [39] Re-COF-TAFB Reaction in Ethanol for 3h Reflux heating method 104.13%(10000@5 A·g -1 ) This work 4. Conclusion This paper synthesized successfully COF-TAFB using reflux heating and solvothermal method, respectively, and compared the effects of these two methods on the structure and electrochemical properties of the synthesized products under the same conditions. It provides new insights for the subsequent synthesis of covalent organic frameworks. The comparative results show that under the same synthesis temperature and time, COFs prepared by the reflux heating method exhibit superior performance, with a higher specific surface area of 143.96 m 2 ·g -1 and a higher specific capacitance of 248 F·g -1 (at 0.1 A·g -1 ), with a capacitance retention rate exceeding 60%. Further analysis through the material's kinetic testing shows that after 10,000 cycles in stability tests, the capacitance retention rate can reach up to 104.13%, demonstrating its incredible cycling stability. This work indicates that synthesizing covalent organic frameworks using the reflux heating method can enhance the electrochemical performance of materials. Declarations Acknowledgments Authors thank for financial support by the National Natural Science Foundation of China (52073227), Shaanxi Province Technological Innovation Guidance Special (2021QFY04-01) and technical support by Analytical Instrumentation Center of XUST. Declaration of interest statement We declare that we have no conflict of commercial or associative interest exits in the submission of the manuscript. We would like to declare on behalf of all the authors that the described work is an original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the enclosed manuscript. Author Contribution Shanxin Xiong: Writing - Review & Editing, Supervision, Funding acquisition Ke Fang: Writing - Original Draft, Investigation, Formal analysisKerui Zhang; Jingru Guo: Resources, Investigation, Data CurationMin Chen; Juan Wu: Visualization Yukun Zhang; Xiaoqin Wang: ConceptualizationChunxia Hua; Jia Chu: Project administrationRunlan Zhang; Chenxu Wang: MethodologyMing Gong: Funding acquisitionBohua Wu: Funding acquisitionJuan Zhang: Validation References Mousa AO, Chuang C-H, Kuo S-W, Mohamed MG (2023) Strategic Design and Synthesis of Ferrocene Linked Porous Organic Frameworks toward Tunable CO 2 Capture and Energy Storage. INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES 24:12371. Liu X, Yang F, Wu L, et al (2022) Ionic liquid-loaded covalent organic frameworks with favorable electrochemical properties as a potential electrode material. Microporous and Mesoporous Materials 336:111906. 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Xiong S, Liu J, Wang Y, et al (2021) synthesis of triphenylamine-based covalent organic framework nanofibers with excellent cycle stability for supercapacitor electrodes. J Appl Polym Sci 139:51510. Liu S, Yao L, Lu Y, et al (2019) All-organic covalent organic framework/polyaniline composites as stable electrode for high-performance supercapacitors. MATERIALS LETTERS 236:354–357. Wei H, Ning J, Cao X, et al (2018) Benzotrithiophene-Based Covalent Organic Frameworks: Construction and Structure Transformation under lonothermal Condition. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 140:11618–11622. Halder A, Ghosh M, Khayum M A, et al (2018) Interlayer Hydrogen-Bonded Covalent Organic Frameworks as High-Performance Supercapacitors. J Am Chem Soc 140:10941–10945. Khattak AM, Ghazi ZA, Liang B, et al (2016) A redox-active 2D covalent organic framework with pyridine moieties capable of faradaic energy storage. J Mater Chem A 4:16312–16317. Scheme Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files scheme.png Scheme.1 Schematic diagram of the synthesis of So-COF-TAFB and Re-COF-TAFB Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 30 Jun, 2024 Reviews received at journal 23 Jun, 2024 Reviews received at journal 22 Jun, 2024 Reviewers agreed at journal 16 Jun, 2024 Reviewers agreed at journal 11 Jun, 2024 Reviewers agreed at journal 11 Jun, 2024 Reviewers agreed at journal 10 Jun, 2024 Reviews received at journal 05 Jun, 2024 Reviewers agreed at journal 30 May, 2024 Reviewers invited by journal 30 May, 2024 Submission checks completed at journal 28 May, 2024 Editor assigned by journal 28 May, 2024 First submitted to journal 27 May, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4487665","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":312937036,"identity":"6dd9b943-20a7-4f70-8dff-7f1ab7c02f24","order_by":0,"name":"Shanxin Xiong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2UlEQVRIiWNgGAWjYDACZgglh8olRosxEDM2EKcFChIbiNZicJz52MMvfw6nb7iR/vwBQ4V1YgP72QN4tUg2s6Uby7al5c6ckWPYwHAmPbGBJy8BrxZ+Zh4zackGm9x+iRzGBsa2w4kNEjwGeLWwgbRI/JFIZ5NIf9jA+I8ILSBbJD+w2STwSyQYNjA2EKEF6Jc0aca2NMOZPW8MZyQcSzdu48nBr8Xg/OFjkj/+HJY3OJ7+4MOHGmvZfvYz+LWAADMPjJUA8h1B9UDA+IMYVaNgFIyCUTByAQAnXj6HZEz3SAAAAABJRU5ErkJggg==","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Shanxin","middleName":"","lastName":"Xiong","suffix":""},{"id":312937037,"identity":"8e0d607e-8901-40df-af72-e65b54e8bbde","order_by":1,"name":"Ke Fang","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Ke","middleName":"","lastName":"Fang","suffix":""},{"id":312937038,"identity":"9d026c2b-9c27-48cc-8d94-cf9df6789b80","order_by":2,"name":"Kerui Zhang","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Kerui","middleName":"","lastName":"Zhang","suffix":""},{"id":312937039,"identity":"b4d692a8-e3c3-4287-93eb-f08e167d572e","order_by":3,"name":"Jingru Guo","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Jingru","middleName":"","lastName":"Guo","suffix":""},{"id":312937040,"identity":"06240e64-feef-4ddc-8568-e83a5322e692","order_by":4,"name":"Min Chen","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Min","middleName":"","lastName":"Chen","suffix":""},{"id":312937041,"identity":"25d1e077-c92c-47ec-ae6d-9d443c42ebf6","order_by":5,"name":"Juan Wu","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Juan","middleName":"","lastName":"Wu","suffix":""},{"id":312937042,"identity":"ca8291b0-ae11-4dde-b6c1-d70766b25f2f","order_by":6,"name":"Yukun Zhang","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Yukun","middleName":"","lastName":"Zhang","suffix":""},{"id":312937043,"identity":"62d22876-7c6c-4711-a325-9dbd6c26e2d3","order_by":7,"name":"Xiaoqin Wang","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Xiaoqin","middleName":"","lastName":"Wang","suffix":""},{"id":312937044,"identity":"a607d371-d7fa-4df2-9dc2-5c9ef557dabc","order_by":8,"name":"Chunxia Hua","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Chunxia","middleName":"","lastName":"Hua","suffix":""},{"id":312937045,"identity":"a1781d77-1401-4c28-8339-66e48eae939e","order_by":9,"name":"Jia Chu","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Jia","middleName":"","lastName":"Chu","suffix":""},{"id":312937046,"identity":"227558cf-ca04-4d7d-9cd0-34a4e48a0835","order_by":10,"name":"Runlan Zhang","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Runlan","middleName":"","lastName":"Zhang","suffix":""},{"id":312937047,"identity":"2ec9c550-cd42-4a6a-8515-a2c1e5b3ef68","order_by":11,"name":"Chenxu Wang","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Chenxu","middleName":"","lastName":"Wang","suffix":""},{"id":312937048,"identity":"de95eb58-881a-4e4d-b37f-62e6e012cda0","order_by":12,"name":"Ming Gong","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Ming","middleName":"","lastName":"Gong","suffix":""},{"id":312937049,"identity":"f6a49dd9-8a45-4862-8cd8-7d6cab2353d2","order_by":13,"name":"Bohua Wu","email":"","orcid":"","institution":"Xi'an University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Bohua","middleName":"","lastName":"Wu","suffix":""},{"id":312937050,"identity":"f6f4a200-c2d6-446d-80a3-380554861bf8","order_by":14,"name":"Juan Zhang","email":"","orcid":"","institution":"Training Base of Army Engineering University","correspondingAuthor":false,"prefix":"","firstName":"Juan","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2024-05-28 02:51:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4487665/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4487665/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58116669,"identity":"1890fcfc-9667-4b45-933e-2cdb6cc11893","added_by":"auto","created_at":"2024-06-11 11:00:25","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1065069,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of So-COF-TAFB at 85 ℃ with reaction time of 2 h(a);3 h(b);4 h(c), SEM images of Re-COF-TAFB at 85 ℃ with reaction time of 2 h(d);3 h(e);4 h(f)\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/6f3a8db920c1822c0d9e34f9.png"},{"id":58116674,"identity":"b0225d29-4fa8-4e68-a217-4387fecc99a0","added_by":"auto","created_at":"2024-06-11 11:00:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":680905,"visible":true,"origin":"","legend":"\u003cp\u003eIR spectra of So-COF-TAFB and Re-COF-TAFB as well as TAPA and TFB (a), Raman spectra (b), PXRD of COF-TAFB and AA Stacking Model (c), Pawley refinements against the PXRD of Re-COF-TAFB\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/1c76031456605a0cb8d8948c.png"},{"id":58117242,"identity":"2f1c5a71-f6c7-4216-a82b-fcd3ae56db25","added_by":"auto","created_at":"2024-06-11 11:08:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":607784,"visible":true,"origin":"","legend":"\u003cp\u003eBET pattern and pore size distribution illustration of So-COF-TAFB (a), BET pattern and pore size distribution illustration of Re-COF-TAFB (b), TGA pattern of So-COF-TAFB (c) and TGA analysis pattern of Re-COF-TAFB (d)\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/3d4b4afbd07ffe3ce79b9df8.png"},{"id":58116670,"identity":"25d9132f-176a-459c-bd11-be19b84fbd87","added_by":"auto","created_at":"2024-06-11 11:00:25","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":692002,"visible":true,"origin":"","legend":"\u003cp\u003eCV curves of So-COF-TAFB (a),and Re-COF-TAFB (b), GCD curves of So-COF-TAFB and rate performance (c), and GCD curves of Re-COF-TAFB and rate performance (d).\u003c/p\u003e","description":"","filename":"Fig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/9f8b91b44dfab9dc72626772.png"},{"id":58116672,"identity":"ac0a5d4e-ef6b-443e-a439-e4ca5a3cd42e","added_by":"auto","created_at":"2024-06-11 11:00:25","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":572322,"visible":true,"origin":"","legend":"\u003cp\u003eThe Nyquist plot of Re-COF-TAFB (a), The Nyquist plot of So-COF-TAFB (b), Capacitance retention and coulomb efficiency of So-COF-TAFB for 10000 cycles at 5 A·g\u003csup\u003e-1\u003c/sup\u003e (c), and Re-COF-TAFB for 10000 cycles at 5 A·g\u003csup\u003e-1\u003c/sup\u003e (d)\u003c/p\u003e","description":"","filename":"Fig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/338afa372097d6e33d7ff9c9.png"},{"id":58118217,"identity":"2bb852bc-64f6-40e1-9875-c39e7ce02819","added_by":"auto","created_at":"2024-06-11 11:24:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4402451,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/88eb2608-f53d-4d69-a568-61e886108ac4.pdf"},{"id":58117561,"identity":"bb42489c-b43a-414b-993e-52964ea44220","added_by":"auto","created_at":"2024-06-11 11:16:25","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":216917,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme.1 \u003c/strong\u003eSchematic diagram of the synthesis of So-COF-TAFB and Re-COF-TAFB\u003c/p\u003e","description":"","filename":"scheme.png","url":"https://assets-eu.researchsquare.com/files/rs-4487665/v1/ed8f2fad5b377e4500ce0a74.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Design of Flexible and Green Chemistry Synthesis Method for Highly Crystalline COFs for Supercapacitor Applications ","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eDue to the continuous deterioration of the environment caused by greenhouse effect, the demand for energy sources that do not emit greenhouse gases is constantly increasing[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Therefore, we urgently need a method to collect and store energy efficiently. Supercapacitors have received widespread attention due to their high power density, long lifespan[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], and fast charging and discharging speed[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The energy storage process in supercapacitors involves two main mechanisms. First one is Electric double layer capacitor (EDLC), which stores energy by forming positive and negative charge layers at the electrolyte/electrode interface[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Second one is pseudocapacitive mechanism, which relies on reversible redox reactions for energy storage[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The working mechanisms of these supercapacitors exhibit significant differences[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The electrode material plays a crucial role in the electrochemical performance of supercapacitors, so it is necessary to develop suitable electrode materials[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Some carbon-related materials, such as carbon nanotubes, graphene[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and porous carbon[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], are frequently used in EDLC[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Transition metal oxides are the most classic pseudocapacitive electrode materials, but new materials such as covalent organic frameworks(COFs)[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], perovskites[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], chalcogenides[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], and MXenes[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] have also shown tremendous potential in the application of pseudocapacitive electrodes[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCOFs are crystalline organic polymers[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] with ordered pores and periodic frameworks, primarily composed of light elements[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] and synthesized through reversible condensation reactions to form stable structures due to dynamic covalent chemistry[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Conjugated layer structure can provide nanoscale stacked channels for ion transport, improving electrochemical performance[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].COFs can be prepared through various reactions, such as diazonium coupling, triazine formation[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], and imine condensation[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The redox activity of COFs mainly relies on the reversible reactions of the building block. The formation of imine bonds through Schiff base reaction is a typical example[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] to synthesize COFs. Common methods for preparing COFs include solvothermal synthesis, mechanochemical synthesis, solvent-free method[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], and plasma-induced synthesis, etc[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Since the emergence of COFs materials in 2005, for a long time, COFs' synthesis has mainly been carried out using solvothermal method[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], often requiring high-temperature degassing and sealing treatments. However, this method often requires high temperature and high pressure conditions[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], as well as the use of organic solvents with high boiling points and toxcity[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Due to the potential safety issues caused by harsh conditions, mild synthetic methods may be considered to prepare COFs, such as mechanochemical and reflux heating methods. Mechanochemical synthesis was once considered a promising alternative to solvothermal method for synthesizing COFs[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Bishnu P. Biswal et al[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], successfully synthesized three COFs with excellent chemical stability using a mechanochemical synthesis method at room temperature. However, this method results in lower crystallinity and limited control over morphology during the synthesis process[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. To overcome the limitations of traditional methods, the heating reflux method can be considered for the synthesis of COFs, which combines the advantages of the solvothermal and mechanical ball milling methods, creating COFs under mild conditions without needing high-boiling-point solvents. Wang et al[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], have successfully developed a simple solution reflux synthesis method in their study. The COF-300 synthesized using this method exhibits excellent crystallinity and high porosity, effectively enhancing the synthesis efficiency and performance of covalent organic framework materials. By adjusting the heating temperature and time, the pore structure and molecular arrangement of COFs can be precisely controlled, creating high-performance COFs materials. Therefore, exploring the synthesis methods of COFs is of great significance for achieving safety, reliability, environmental friendliness, and large-scale production.\u003c/p\u003e \u003cp\u003eOur research aims to contribute to a more sustainable practice in the electrochemistry field based on the challenges discussed earlier in COFs synthesis, particularly the safety issues associated with solvothermal method. Recognizing the need for safe synthesis of COFs materials, we have shifted our focus to innovative synthesis technologies that can improve safety while reduce the ecological impact. In this study, COF-TAFB was synthesized by reflux heating and solvothermal method using ethanol as solvent, and tri (4-aminophenyl) amine (TAPA) and trimesic acid (TFB) as building units. Compared with the solvothermal method, the heating reflux method has the advantages of mild synthesis conditions, high safety, simple operation and scalability. Herein, the comparative study was carried out through investigating the structural and performance difference of Re-COF-TAFB and So-COF-TAFB induced by different synthesis methods.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eTri(4-aminophenyl)amine (TAPA) and tris(benzaldehyde) (TFB) were purchased from Shanghai Kylpharm Co., Ltd, China. Ethanol (EtOH) was purchased from Tianjin Kemiou Chemical Reagent Co., Ltd, China. N, N-Dimethylformamide (DMF) was purchased from Tianjin Fuyu Chemical Co., Ltd, China. Conductive carbon black was purchased from Timcal Co., Ltd, Switzerland. Polyvinylidene fluoride (PVDF) was purchased from Suzhou Yilongsheng Energy Technology Co., Ltd, China. All chemicals were used without further purification.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Synthesis of So-COF-TAFB and Re-COF-TAFB\u003c/h2\u003e \u003cp\u003eThe synthesis of So-COF-TAFB was executed using the following steps: TAPA (0.08711 g, 0.3 mmol) and TFB (0.04864 g, 0.3 mmol) were mixed in 15 mL of EtOH (99.7% purity). The mixture was subjected to ultrasonic agitation for 30 min until complete dissolution of the monomers. The clear solution was transferred into a Teflon reactor and heated at 85\u0026deg;C for different hours. After cooling, the reaction mixture was transferred into centrifuge tubes and washed with DMF until the supernatant was colorless. Subsequent washings with anhydrous ethanol were performed three to five times to remove residual DMF. The product was dried at 60\u0026deg;C for 24 hours in a vacuum oven. Finally, the dry product was ground using an agate mortar to yield red So-COF-TAFB powder.\u003c/p\u003e \u003cp\u003eThe following procedure prepares Re-COF-TAFB: Transfer the same monomer solution to a three-necked flask, purged with nitrogen gas and sealed before the assembly of the reflux apparatus. The setup was placed in an oil bath for the various reaction time at 85\u0026deg;C. After the reaction, the product was cooled and washed with DMF until the supernatant became colorless, followed by three to five washes with anhydrous ethanol. Subsequently, the material was dried at 60\u0026deg;C for 24 hours in a vacuum oven. Finally, the dried product was ground in an agate mortar to obtain red Re-COF-TAFB powder. Scheme.1 shows the schematic diagram of the synthesis process of COF-TAFB.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Preparation of electrodes with So-COF-TAFB and Re-COF-TAFB active materials\u003c/h2\u003e \u003cp\u003eThe electrode material was prepared by mixing So-COF-TAFB powder, conductive carbon black, and PVDF in a mass ratio of 6:3:1. The mixture was ground certain amount of with DMF in an agate mortar to obtain even paste. The paste was then ultrasonicated for 30 min in an ultrasonic cleaner to achieve a uniformly dispersed slurry. The slurry was evenly spread over a 1\u0026times;4 cm\u003csup\u003e2\u003c/sup\u003e carbon paper substrate with the target coating area about 1\u0026times;1 cm\u003csup\u003e2\u003c/sup\u003e. The coated substrate was then dried in a vacuum oven at 60\u0026deg;C for 12 hours, resulting in a final material loading of approximately 0.7 to 1 mg/cm\u003csup\u003e2\u003c/sup\u003e. The procedure for preparing the electrode material of Re-COF-TAFB was identical to the process utilized in the fabrication of So-COF-TAFB.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Characterizations\u003c/h2\u003e \u003cp\u003ePhenom/Pro scanning electron microscope (SEM) was used to observe the microstructure of So-COF-TAFB and Re-COF-TAFB. Perkin-Elmer FT-IR spectrometer was employed to acquire the samples' Fourier-transform infrared (FTIR) spectra within the 40-4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e range by the KBr method. The Raman spectra (Raman) were collected using a Renishaw inVia reflectance confocal micro-Raman spectrometer equipped with a 785 nm laser source. Thermogravimetric analysis (TGA) was performed on a Setaram Labsys Evo TG-DSC integrated thermal analyzer from France, measuring under a nitrogen atmosphere with a 5\u0026deg;C/min heating rate from 50\u0026deg;C to 800\u0026deg;C. The crystal structure of the samples was examined using a German Bruker D8A25 instrument (PXRD, Cu Kα radiation, λ\u0026thinsp;=\u0026thinsp;1.5418 \u0026Aring;), with a scan range of 2θ\u0026thinsp;=\u0026thinsp;2 to 50\u0026deg;. The Brunauer\u0026ndash;Emmett\u0026ndash;Teller (BET) specific surface area and pore structure characteristics were measured using a Micromeritics ASAP 2020 specific surface area analyzer through N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption measurements at 77 K. Cyclic voltammetry (CV) tests were conducted using a CHI660E electrochemical workstation in a 1 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e electrolyte. The scan rates were 10, 20, 50, 75, and 100 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. For Galvanostatic charge-discharge (GCD) tests, the current densities were varied at 0.1, 0.2, 0.5, 1, 2, and 5 A\u0026middot;g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Electrochemical impedance spectroscopy (EIS) measurements were performed over a frequency range of 0.01 Hz to 10\u003csup\u003e5\u003c/sup\u003e Hz. The specific capacitance of the material from the GCD curves can be estimated using the formula (1) below:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\begin{array}{c}C=\\frac{{I\\varDelta t}_{d}}{m\\varDelta V} \\left(\\text{1}\\right)\\end{array}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eIn the above formula, C (F\u003c/span\u003e\u0026middot;\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eg\u003c/span\u003e\u003csup\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e\u0026minus;\u0026thinsp;1\u003c/span\u003e\u003c/sup\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e) represents the specific capacitance of the material, I (A) is the discharge current\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\varDelta t}_{d}\\)\u003c/span\u003e\u003c/span\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e(s) is the discharge time, m (g) is the mass of active material on the collector, and\u003c/span\u003e \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta V\\)\u003c/span\u003e\u003c/span\u003e \u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003e(V) is the potential window of electrode materials.\u003c/span\u003e\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003ch2\u003e3.1 The microstructure of So-COF-TAFB and Re-COF-TAFB\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eAs depicted in Fig.1, the effects of varying reaction durations on the microstructure of COFs were investigated. Figs.1 (a, b, c) and (d, e, f) showcase the microstructures of So-COF-TAFB and Re-COF-TAFB at reaction time of 2 hours, 3 hours, and 4 hours, respectively. It can be observed that the reaction time plays a crucial role in determining the product morphology. If the reaction time is set to 2 hours, the monomer does not get enough time to react, resulting in uneven morphology and particle size. When the reaction time is increased to 3 hours, a highly ordered and uniform sphere structure is formed due to the dynamic equilibrium reached by the crystal growth and aggregation process. However, if the reaction time is increased to 4 hours, the overreacted crystals may start aggregating into larger particles, leading to irregular microscopic morphology. When the reaction time is set to 3 h, there is a significant difference in particle size between So-COF-TAFB (Fig.1(b)) and Re-COF-TAFB (Fig.1(e)). The average particle size of So-COF-TAFB and Re-COF-TAFB are 1.706 \u0026mu;m and 0.511 \u0026mu;m, respectively. The oversized particle size of So-COF-TAFB will reduce specific surface area. Therefore, it will affect the electrochemical performance of COF-TAFB. It\u0026apos;s noteworthy that uniform microstructure in materials can substantially enhance the performance of supercapacitors. This uniformity ensures more consistent electrochemical properties and can lead to improved energy storage efficiency. To comprehensively understand the impact of different synthesis methods, we also employed additional characterization techniques to elucidate further the relationship between microstructure and the overall properties of COFs.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003e3.2 Structure Characterization of So-COF-TAFB and Re-COF-TAFB\u003c/h2\u003e\n\u003cp\u003eFT-IR spectroscopy can prove the successful synthesis of So-COF-TAFB and Re-COF-TAFB. As shown in Fig.2 (a), So-COF-TAFB and Re-COF-TAFB both exhibit characteristic peaks of Schiff base -C=N- stretching vibrations at positions of 1621 cm\u003csup\u003e-1\u003c/sup\u003e and 1634 cm\u003csup\u003e-1\u003c/sup\u003e, while the distinct peaks of -NH\u003csub\u003e2\u003c/sub\u003e at 3409 cm\u003csup\u003e-1\u003c/sup\u003e and 3338 cm\u003csup\u003e-1\u003c/sup\u003e for TAPA, as well as the characteristic peak of -CHO at 1648 cm\u003csup\u003e-1\u003c/sup\u003e for TFB, almost disappear. It indicates that the -C=N- bond is generated during the synthesis process through the Schiff base reaction. Through the Raman spectra (Fig.2 (b)) of the samples, it can be further observed that the -C=N- bond at 1586 cm\u003csup\u003e-1\u003c/sup\u003e and 1587 cm\u003csup\u003e-1\u003c/sup\u003e are formed during the synthesis process, while the -C=O- bond at 1434 cm\u003csup\u003e-1\u003c/sup\u003e and 1428 cm\u003csup\u003e-1\u003c/sup\u003e, as well as the -N-H- bond at 1354 cm\u003csup\u003e-1\u003c/sup\u003e and 1355 cm\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003eare disappeared. This provides further evidence for the successful synthesis of So-COF-TAFB and Re-COF-TAFB.\u003c/p\u003e\n\u003cp\u003eIn this study, we conducted a detailed analysis of the material\u0026apos;s crystal structure using PXRD techniques.\u0026nbsp;Fig.2 (c) displays the PXRD pattern of\u0026nbsp;COF-TAFB and AA Stacking Model, where peaks at 4.83\u0026deg;, 9.42\u0026deg;,11.1\u0026deg;, and 25.03\u0026deg;, corresponding to the (100), (110), (200), and (001) crystal planes of COFs, respectively.\u0026nbsp;The high intensity of the (100) peak suggests a well-defined periodic structure in the material. And the characteristics of the (001) plane suggest a vertical stacking nature of the material, which could influence its porous structure. This feature is likely to significantly enhance the ion diffusion rate and energy storage efficiency in electrochemical energy storage devices. From the PXRD characteristic peaks of Re-COF-TAFB\u0026nbsp;(Fig.2 (c)), we can see that the (100) crystal plane (4.83\u0026deg;) and (001) crystal plane (25.03\u0026deg;) are distributed in the graph. However, the PXRD pattern of So-COF-TAFB(Fig.2 (c)) show that except for the 100 crystal plane, the rest of the crystal planes do not show strong expression, so we judge that the crystallinity of Re-COF-TAFB is more excellent than that of So-COF-TAFB. the weakness of the (001) plane indicates that AA stacking is short in the crystal material, which leads to instability in the channel structure, potentially further limits ion diffusion and energy storage efficiency. It is not difficult to discern through comparison that, although So-COF-TAFB possesses a good periodic structure, Re-COF-TAFB exhibits a more stable AA stacking structure. The stable AA stacking structure of Re-COF-TAFB is conducive to further accelerating the transfer of ions and charges in the electrolyte, endowing the material with superior electrochemical properties.\u003c/p\u003e\n\u003cp\u003eThe PXRD results for Re-COF-TAFB were refined using the Pawley method, yielding lattice parameters a = b = 16.6722 \u0026Aring;, c = 3.4051 \u0026Aring;, with \u0026alpha; = \u0026beta; = 90\u0026deg;, and \u0026gamma; = 120\u0026deg;. The refined result with Rwp=10% and Rp=6.99%. The degree of fit between the refined PXRD patterns and experimental data was evaluated using a difference plot. As depicted in Fig.2d, the refined PXRD pattern closely matches the experimentally obtained PXRD pattern. The PXRD results confirmed that Re-COF-TAFB possesses an AA stacking, long-range ordered porous structure.\u003c/p\u003e\n\u003cp\u003eAs shown in Fig.3 (a), we can see that the adsorption and desorption curves of So-COF-TAFB are roughly similar, but the specific surface area of So-COF-TAFB is only 110.2 m\u003csup\u003e2\u003c/sup\u003e\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e. In Fig.3 (b), the specific surface area analysis of Re-COF-TAFB material. The adsorption and desorption curves of Re-COF-TAFB can be seen to have a peak at P/P\u003csub\u003e0\u003c/sub\u003e=1, and there is a bulge in the low P/P0 region, which belongs to type IV isotherm, there is a desorption hysteresis between the two curves. This indicates that Re-COF-TAFB may have a porous structure[33]. According to the pore size distribution curve of Re-COF-TAFB(Inset of Fig.3 (a)), it can be observed that its pore size distribution is mainly concentrated in the mesoporous range (2-50 nm). Through calculating, the specific surface area of Re-COF-TAFB was determined to be 143.96 m\u003csup\u003e2\u003c/sup\u003e\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e. Compared to the\u0026nbsp;solvothermal\u0026nbsp;method, Re-COF-TAFB prepared by the reflux heating method has a higher specific surface area. This is consistent with the previous SEM test results. A larger specific surface area has a positive impact on improving the electrochemical performance of supercapacitors.\u003c/p\u003e\n\u003cp\u003eThe thermal stability of porous materials is a significant performance index. It is observable that both So-COF-TAFB and Re-COF-TAFB exhibit a weight loss of less than 7% before 450 \u0026deg;C. This indicates that these materials possess excellent thermal stability. Moreover, it is not difficult to see that Re-COF-TAFB exhibits better thermal stability, having lost 45.08% of its weight throughout the entire thermal stability test, compared to the 48.49% weight loss of So-COF-TAFB. Excellent thermal stability indicates that the material is not easily degraded under high temperature conditions, which can effectively prolong the service life of supercapacitors.\u003c/p\u003e\n\u003ch2\u003e3.3 Electrochemical properties of So-COF-TAFB and Re-COF-TAFB\u003c/h2\u003e\n\u003cp\u003eTo investigate the differences in electrochemical performance of COFs materials synthesized by two different methods, CV, GCD, and EIS electrochemical analysis methods were used to analyze and test the prepared electrodes. The CV results of the electrode material indicate that within the scanning rate range of 10-100 mV\u0026middot;s\u003csup\u003e-1\u003c/sup\u003e, the shape of the test curve remains relatively stable and exhibits certain symmetry. This indicates that the assembled supercapacitor possesses electrochemical activity and reversibility. Compared to So-COF-TAFB(Fig.4 (a)), the CV curves of Re-COF-TAFB(Fig.4 (b)) tends towards a more \u0026quot;rectangular\u0026quot; shape, suggesting that Re-COF-TAFB material may possess superior double-layer capacitance characteristics. The presence of oxidation-reduction peaks in the curve also indicates the pseudocapacitive properties of the material. The CV curves of Re-COF-TAFB enclose a larger area, implying that Re-COF-TAFB has a higher specific capacitance. This corresponds to the previous SEM and BET test results, where the uniform morphology and larger surface area are more conducive to exhibiting excellent electrochemical performance. Fig.4 (d) shows the GCD curves of Re-COF-TAFB, which has an approximate \u0026quot;triangular\u0026quot; shape with a charging plateau in the middle. As the current density increases, there is no significant change in the shape of the curve, the capacitance decreases from 248 F\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e (0.1 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e) to 151 F\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e (5 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e). The GCD test results of So-COF-TAFB are shown in Fig.4 (c), the capacitance decreased from 232 F\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e (0.1 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e) to 142 F\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e (5 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e). Through GCD curves, we can calculate that with the increase of current density, the capacitance retention rate of Re-COF-TAFB (Inset of Fig.4 (d)) decreases little and keeps above 60% all the time.\u0026nbsp;Through impedance analysis of EIS, the electrochemical characteristics of Re-COF-TAFB and So-COF-TAFB were further analyzed. As shown in Fig.5, the Nyquist plots of So-COF-TAFB and Re-COF-TAFB (Fig.5 (a) and (b)) in the frequency range from 0.01 to 10\u003csup\u003e5\u003c/sup\u003e Hz are depicted. The plots demonstrate low interfacial impedance and good gap conductivity[34]. It can be observed that nearly vertical lines are present in the low-frequency region, indicating their excellent capacitive properties. Combined with the previous CV and GCD results, it can be found that the electrochemical performance of Re-COF-TAFB is better than So-COF-TAFB as a whole. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe cyclic stability tests of So-COF-TAFB and Re-COF-TAFB (Fig.5 (c) and (d)), showing that their capacitance retention rates after 10,000 cycles were 102.58% and104.13%, respectively. It can be observed that their capacitance retention rates are all greater than 100%. This result ranks among the top in the published research reports, as shown in Table 1. We speculate that this is due to the insufficient contact between the electrode and electrolyte when the electrode enters the electrolyte, resulting in an incomplete manifestation of electrochemical performance. As the number of cycles increases, the contact between the electrode and electrolyte becomes more sufficient. After a long period of charge-discharge, there is a specific pore expansion effect in the electrode material, which leads to an increasing trend in capacitance retention rate[35]. With the increase in the number of cycles, the Coulomb efficiency of Re-COF-TAFB and So-COF-TAFB remains unchanged. This is due to the excellent thermal and structural stability of COF-TAFB. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFurthermore, test results indicate that So-COF-TAFB exhibits a slightly lower capacitance retention rate than Re-COF-TAFB.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOverall, comparing reflux heating and solvent thermal methods for synthesizing the same COFs under identical conditions, the product from reflux heating exhibits superior electrochemical performance due to its more uniform microscopic morphology, smaller particle size, and larger specific surface area. Additionally, the reflux heating method offers a simpler and milder synthesis process, avoiding the high temperature and pressure associated with traditional solvent thermal methods. This not only enhances the environmental friendliness of the approach but also holds promise for facilitating easier and more efficient synthesis in the future. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable.1\u0026nbsp;\u003c/strong\u003eReview of COFs Synthesized by Different Methods for Supercapacitor\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"633\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.851500789889414%\"\u003e\n \u003cp\u003e\u003cstrong\u003eElectrode materials\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.85466034755134%\"\u003e\n \u003cp\u003e\u003cstrong\u003eReaction medium\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;and Reaction time\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.429699842022117%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSynthesis method\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"32.859399684044234%\"\u003e\n \u003cp\u003e\u003cstrong\u003eRetention (%)(cycle@current\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003edensity (A/g))\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.004739336492891%\"\u003e\n \u003cp\u003e\u003cstrong\u003eRef\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.851500789889414%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTpPa-COF@PANI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.85466034755134%\"\u003e\n \u003cp\u003eReaction in mesitylene, 1, 4-dioxane, acetic acid for 3 days;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.429699842022117%\"\u003e\n \u003cp\u003eSolvothermal method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"32.859399684044234%\"\u003e\n \u003cp\u003e83%([email protected] A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.004739336492891%\"\u003e\n \u003cp\u003e[36]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.851500789889414%\"\u003e\n \u003cp\u003e\u003cstrong\u003eBTT-DADP COF-700\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.85466034755134%\"\u003e\n \u003cp\u003eReaction in ZnCl\u003csub\u003e2\u003c/sub\u003e for 20h;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.429699842022117%\"\u003e\n \u003cp\u003eIonothermal synthesis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"32.859399684044234%\"\u003e\n \u003cp\u003e77.5%(10000@10 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.004739336492891%\"\u003e\n \u003cp\u003e[37]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.851500789889414%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTpOMe-DAQ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.85466034755134%\"\u003e\n \u003cp\u003eReaction in 2M/3M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.429699842022117%\"\u003e\n \u003cp\u003eMechano-chemical\u003c/p\u003e\n \u003cp\u003egrinding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"32.859399684044234%\"\u003e\n \u003cp\u003e65%(50000@5 mA\u0026middot;cm\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.004739336492891%\"\u003e\n \u003cp\u003e[38]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.851500789889414%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTaPa-Py COF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.85466034755134%\"\u003e\n \u003cp\u003eReaction in mesitylene, 1, 4-dioxane, acetic acid for 3 days;-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.429699842022117%\"\u003e\n \u003cp\u003eSolvothermal method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"32.859399684044234%\"\u003e\n \u003cp\u003e92%(6000@2 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.004739336492891%\"\u003e\n \u003cp\u003e[39]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"17.851500789889414%\"\u003e\n \u003cp\u003e\u003cstrong\u003eRe-COF-TAFB\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.85466034755134%\"\u003e\n \u003cp\u003eReaction in Ethanol for 3h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.429699842022117%\"\u003e\n \u003cp\u003eReflux heating method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"32.859399684044234%\"\u003e\n \u003cp\u003e104.13%(10000@5 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.004739336492891%\"\u003e\n \u003cp\u003eThis work\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis paper synthesized successfully COF-TAFB using\u0026nbsp;reflux heating\u0026nbsp;and solvothermal method, respectively, and compared the effects of these two methods on the structure and electrochemical properties of the synthesized products under the same conditions. It provides new insights for the subsequent synthesis of covalent organic frameworks. The comparative results show that under the same synthesis temperature and time, COFs prepared by the\u0026nbsp;reflux heating method\u0026nbsp;exhibit superior performance, with a higher specific surface area of 143.96 m\u003csup\u003e2\u003c/sup\u003e\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e and a higher specific capacitance of 248 F\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e (at 0.1 A\u0026middot;g\u003csup\u003e-1\u003c/sup\u003e), with a capacitance retention rate exceeding 60%. Further analysis through the material\u0026apos;s kinetic testing shows that after 10,000 cycles in stability tests, the capacitance retention rate can reach up to 104.13%, demonstrating its incredible cycling stability. This work indicates that synthesizing covalent organic frameworks using the reflux heating method can enhance the electrochemical performance of materials.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors thank for financial support by the National Natural Science Foundation of China (52073227), Shaanxi Province Technological Innovation Guidance Special (2021QFY04-01) and technical support by Analytical Instrumentation Center of XUST.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of interest statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe declare that we have no conflict of commercial or associative interest exits in the submission of the manuscript. We would like to declare on behalf of all the authors that the described work is an original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the enclosed manuscript.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eShanxin Xiong: Writing - Review \u0026amp; Editing, Supervision, Funding acquisition Ke Fang: Writing - Original Draft, Investigation, Formal analysisKerui Zhang; Jingru Guo: Resources, Investigation, Data CurationMin Chen; Juan Wu: Visualization Yukun Zhang; Xiaoqin Wang: ConceptualizationChunxia Hua; Jia Chu: Project administrationRunlan Zhang; Chenxu Wang: MethodologyMing Gong: Funding acquisitionBohua Wu: Funding acquisitionJuan Zhang: Validation\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMousa AO, Chuang C-H, Kuo S-W, Mohamed MG (2023) Strategic Design and Synthesis of Ferrocene Linked Porous Organic Frameworks toward Tunable CO\u003csub\u003e2\u003c/sub\u003e Capture and Energy Storage. 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MATERIALS LETTERS 236:354\u0026ndash;357.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWei H, Ning J, Cao X, et al (2018) Benzotrithiophene-Based Covalent Organic Frameworks: Construction and Structure Transformation under lonothermal Condition. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 140:11618\u0026ndash;11622.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHalder A, Ghosh M, Khayum M A, et al (2018) Interlayer Hydrogen-Bonded Covalent Organic Frameworks as High-Performance Supercapacitors. J Am Chem Soc 140:10941\u0026ndash;10945.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhattak AM, Ghazi ZA, Liang B, et al (2016) A redox-active 2D covalent organic framework with pyridine moieties capable of faradaic energy storage. J Mater Chem A 4:16312\u0026ndash;16317.\u003c/span\u003e\u003c/li\u003e\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":"Covalent Organic Frameworks, Reflux Heating Method, Solvothermal Synthesis, Supercapacitors, Electrochemical Properties","lastPublishedDoi":"10.21203/rs.3.rs-4487665/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4487665/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCovalent organic frameworks (COFs) have attracted much attention in energy storage due to their porous network structure, large specific surface area, high crystallinity, and pseudocapacitive ability brought by redox reactions. However, the traditional synthesis method of COFs involves toxic solvents and requires high temperatures and pressure. Therefore, it is necessary to develop simple synthesis methods for large-scale practical application of COFs. This study investigated the synthesis and electrochemical properties of two kinds of COFs, which were synthesized through the reflux heating method and solvothermal method using Tri(4-aminophenyl)amine (TAPA) and tris(benzaldehyde) (TFB) as monomers. The results show that COFs synthesized by reflux heating (Re-COF-TAFB) outperforms COFs Synthesized by solvothermal method (So-COF-TAFB) in specific surface area, thermal stability, and electrochemical properties. Re-COF-TAFB has a specific capacitance of 248 F\u0026middot;g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 0.1 A\u0026middot;g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and a capacitance retention rate of 104.13% after 10,000 charge and discharge cycles. This paper contributes to understanding COFs' synthesis methods and their impact on material properties. Reflux heating is highlighted as an efficient technique for developing high-performance COF-based supercapacitors.\u003c/p\u003e","manuscriptTitle":"Design of Flexible and Green Chemistry Synthesis Method for Highly Crystalline COFs for Supercapacitor Applications ","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-11 11:00:21","doi":"10.21203/rs.3.rs-4487665/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-06-30T18:40:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-06-23T14:32:05+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-06-22T06:09:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"53807032611083009843151020597261152974","date":"2024-06-17T01:14:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"94534901247620030458794231927993531326","date":"2024-06-11T04:54:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"17328625147082179992502501576627014176","date":"2024-06-11T04:36:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"208431094697951444896857360465268485829","date":"2024-06-10T16:47:05+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-06-05T08:43:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"105470397625686591909310545049187608750","date":"2024-05-31T02:24:15+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-05-30T13:25:41+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-28T09:44:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-28T09:44:17+00:00","index":"","fulltext":""},{"type":"submitted","content":"Ionics","date":"2024-05-28T02:47:57+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":"2b223968-bc83-41a3-be1b-b19393a565d5","owner":[],"postedDate":"June 11th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2024-07-21T10:02:27+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-11 11:00:21","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4487665","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4487665","identity":"rs-4487665","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}