Preparation and application of quinacridone oxide / reduced graphene oxide organic molecular electrode

Abstract

The invention discloses a preparation method of a quinacridone oxide / reduced graphene oxide organic molecular electrode. The preparation method comprises the following steps: firstly, oxidizing quinacridone molecules (QD) in concentrated HNO3 to obtain quinacridone oxide molecules (OQD); the generated OQD is a nitrogen-containing carbonyl compound with an intramolecular complete pi conjugated structure, reduced graphene oxide (rGO) is taken as a conductive substrate through a non-covalent functionalization strategy, the conductive substrate is anchored on the surface of the reduced graphene oxide by utilizing a solvothermal self-assembly method, and strong pi-pi interaction exists between the OQD and the rGO, so that the OQD is prepared. The conjugated carbonyl all-carbon organic molecular electrode material OQD / rGO is prepared, and the electrochemical performance of the conjugated carbonyl all-carbon organic molecular electrode material OQD / rGO is researched. The all-carbon organic molecule electrode material has high specific capacitance, good rate capability and excellent cycling stability. In addition, in order to research the actual energy storage performance, the asymmetric supercapacitor (PDQ / rGO / / OQD / rGO) assembled by the OQD / rGO and the quinone-rich polymer modified rGO (PDQ / rGO) has excellent energy storage performance.

Description

Technical Field

[0001] This invention relates to a method for preparing an organic molecular electrode material modified with quinacridone oxide and reduced graphene oxide, which is mainly used as a positive electrode material for constructing supercapacitors and belongs to the fields of organic molecular electrode material technology and electrochemical technology. Background Technology

[0002] With the widespread adoption of digital technologies and electronic devices, the world is entering the Fourth Industrial Revolution, which has spurred a strong demand for electrified and low-carbon energy supplies. In the evaluation of energy storage systems, energy density (E) and power density (P) are considered core standards for measuring their performance. Compared to rechargeable batteries, supercapacitors (SCs) exhibit superior power density, enabling rapid charging and discharging, and possess numerous advantages such as long lifespan and highly reliable safety. However, the low energy density of SCs has become an obstacle to their practical application and further development. Therefore, developing high-energy-density SC electrode materials and rationally assembled devices without sacrificing the high power density of SCs is a crucial problem that urgently needs to be solved.

[0003] While traditional inorganic electrode materials based on transition metals have achieved great success in electrochemical storage (SCs) and mature lithium-ion battery technologies, further development is significantly limited by the theoretical limitations of energy density and the scarcity of resources for metals such as cobalt and nickel. As an alternative and complement, organic molecular electrode materials (OMEs), which are abundant and composed of light elements including carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S), have attracted increasing attention in recent years. In addition to their resource sustainability and environmental friendliness, the structural diversity, designability, and flexibility of OMEs also demonstrate great potential in electrochemical energy storage, including energy density, cost-effectiveness, and scalability for practical applications. However, translating this potential into practical applications remains a significant challenge. Although many electrode materials with different organic molecular structures have been reported, OMEs that simultaneously possess high energy density, excellent cycle stability, and low cost are still very scarce.

[0004] Conjugated carbonyl (C=O) compounds (such as quinones and ketones) have become excellent candidates for the preparation of OMEs due to their relatively high redox activity, high Faraday pseudocapacitance, and excellent electrochemical reversibility. The key challenges currently faced are the low conductivity of these commercially available molecules and their dissolution in electrolytes during charge and discharge, which prevents them from fully realizing their capacitive performance, resulting in low coulombic efficiency and poor cycle performance, thus failing to meet their practical applications in energy storage.

[0005] To address these issues, researchers have attempted to composite organic molecules with conductive carbon substrates (such as graphene) to enhance interfacial interactions through physical or chemical means. Graphene, with its high specific surface area, excellent conductivity, and chemical stability, is an ideal conductive framework. While existing chemical bonding strategies (such as covalent modification) can immobilize organic molecules, they may disrupt the sp² structure of graphene, reducing its conductivity. Non-covalent modification based on π-π interactions, however, can preserve the intrinsic properties of graphene while achieving strong interactions between the molecule and the substrate.

[0006] This invention addresses the problems of weak interfacial interactions and rapid capacity decay in existing organic molecule / graphene composite materials by proposing a method for preparing oxidized quinacridone (OQD) / reduced graphene oxide (rGO) electrodes based on non-covalent π-π interactions. By oxidizing QD molecules with nitric acid, the pyrrole nitrogen within the QD molecule is converted to pyridine nitrogen, resulting in a complete intramolecular π-conjugated structure in the oxidized QD, enabling efficient electron transfer and enhancing its π-π interaction with rGO. Combined with a solvothermal self-assembly process, a three-dimensional porous wrinkled structure is constructed, aiming to achieve high specific capacitance, excellent rate performance, and ultra-long cycling stability. This technology not only avoids the resource and environmental problems of traditional metal-based materials but also overcomes the performance limitations of purely organic or carbon-based electrodes through molecular-substrate synergy, providing a new solution for high-energy-density supercapacitors. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing organic molecular electrodes by non-covalent modification of quinacridone with reduced graphene oxide; Another objective of this invention is to study the structure and electrochemical properties of the prepared quinacridone oxide / reduced graphene oxide organic molecule (OQD / rGO) electrode material, for use as a positive electrode material for supercapacitors.

[0008] This invention oxidizes quinacridone to quinacridone oxide molecules with an intact intramolecular π-conjugated structure via nitric acid oxidation. The pyrrole nitrogen within the quinacridone molecule is converted to pyridine nitrogen, enabling efficient electron transfer. The pseudocapacitive material (quinacridone oxide molecule) is effectively composited with an electric double-layer material (reduced graphene oxide). The strong π-π interaction between the intact π-conjugated structure of the quinacridone oxide molecule and the reduced graphene oxide reduces electron transfer paths and accelerates charge transfer in the Faradaic reaction. Furthermore, the rapid Faradaic reaction between the quinone / phenolic groups (O / OH) within the quinacridone oxide molecule and the reduced graphene oxide forms a synergistic effect, which is an effective method to improve the charge storage capacity of organic molecular electrode materials. Finally, OQD is further modified onto GO nanosheets using a simple, green, and economical solvothermal method to form a three-dimensional conductive network structure, resulting in better overall material conductivity. During the hydrothermal process, when OQD is anchored on the rGO surface, GO is simultaneously converted into conductive rGO.

[0009] I. Preparation of quinacridone oxide / reduced graphene oxide organic molecular electrode materials (1) Preparation of oxidized quinacridone: Quinacridone (QD) was added to concentrated nitric acid and stirred for oxidation. After centrifugation, washing and vacuum drying, oxidized quinacridone (OQD) powder was obtained. The oxidation time of quinacridone in concentrated HNO3 was 3-5 h. The mass-to-volume ratio of quinacridone QD to concentrated nitric acid was 25-35 mg / mL. (2) Preparation of mixed dispersion: Graphene oxide (GO) was dispersed in DMF and sonicated, and oxyquinacridone (OQD) powder was dissolved in DMF and sonicated. The two dispersions were mixed and sonicated again. (3) Solvent-thermal reduction self-assembly: The mixture was placed in a high-pressure reactor and reacted at 170~185℃ for 12~14h. After cooling, the product was washed. The washed product was freeze-dried at -50~-20℃ for 12~48h to obtain OQD / rGO electrode material. In the OQD / rGO electrode material, the mass ratio of OQD to rGO was 1:1~1:3. When the mass ratio of OQD to rGO was 1:3, it was OQD / rGO-0.3; when the mass ratio of OQD to rGO was 1:2, it was OQD / rGO-0.5; and when the mass ratio of OQD to rGO was 1:1, it was OQD / rGO-1.

[0010] Figure 1This is a schematic diagram illustrating the synthesis of OQD and OQD-rGO organic molecular electrodes. OQD, prepared by oxidation of QD with concentrated HNO3, is a conjugated nitrogen-containing carbonyl compound with an intramolecular π-conjugated structure, which facilitates electron transport but has poor conductivity. Therefore, it is modified onto a conductive substrate, GO nanosheets, to construct a three-dimensional conductive network structure, thereby achieving better overall material conductivity. Since OQD is poorly soluble in water, it is first dissolved in DMF and then mixed with a GO dispersion. Through solvothermal treatment, the mixed solvent diffuses and exfoliates the GO sheets. Simultaneously, this process induces GO to dehydroxylate, restore π-conjugation, and be reduced to rGO. Simultaneously, OQD is anchored to the rGO surface through non-covalent interactions (π-π, hydrogen bonds, etc.). The introduction of OQD effectively inhibits the re-aggregation and stacking of GO / rGO sheets, forming a porous three-dimensional folded structure. Benefiting from the high conductivity of rGO, this structure achieves efficient electron transport between the OQD and rGO network, synergistically contributing to the double-layer capacitance and pseudocapacitance, thus significantly improving the overall electrochemical performance of the electrode.

[0011] II. Structural Characterization of Organic Molecular Electrode Materials The morphological characteristics of the material were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the structural characteristics of the sample were determined by Fourier transform infrared spectroscopy (FTIRspectra), ultraviolet-visible (UV-vis) absorption spectroscopy and Raman spectroscopy.

[0012] 1. Morphological analysis The morphology and microstructure of the substrate rGO and the organic molecular electrode OQD / rGO were observed and analyzed using field emission scanning electron microscopy (FESEM). Figure 2 Figures a and 2b show a widely interwoven sheet-like network structure, exhibiting a three-dimensional porous structure formed by the stacking of many graphene sheets. This structure is beneficial for the transport of electrolyte ions. Figure 2 As shown in d and 2e, OQD / rGO is similar to rGO, but exhibits a thinner wrinkled layer, making the overall material more porous and forming a three-dimensional interconnected porous structure, which is conducive to the rapid diffusion and storage of electrolyte ions in the material. TEM images of rGO (2c) and OQD / rGO (2f) clearly show that both exhibit a thin, transparent, veil-like structure, indicating that OQD molecules do not exist as a free phase on the rGO surface.

[0013] 2. Fourier transform infrared spectroscopy analysis Figure 3 (a, b) show the Fourier transform infrared (FTIR) spectra of the QD molecule, OQD molecule, rGO, and OQD / rGO-0.5, demonstrating the successful synthesis of OQD and its recombination with rGO. Specifically, the FTIR spectrum of the QD molecule shows NH (3126 cm⁻¹) -1C=O (1714 cm) -1 C=C (1634 cm) -1 ) and CN (1395 cm) -1 Characteristic absorption peaks such as ) are observed. It is noteworthy that after oxidation, the OQD molecule exhibits a peak at 1558 cm⁻¹. -1 A strong characteristic peak is observed at this point, corresponding to the C=N stretching vibration formed after oxidation, and the peak at 3126 cm⁻¹ in the QD molecule is also significant. -1 The disappearance of the NH characteristic peak at 1731, 1628, and 1397 cm⁻¹ proves that the QD molecule has been completely oxidized. The peaks at 1731, 1628, and 1397 cm⁻¹ further confirm that the QD molecule has been completely oxidized. -1 The absorption peak at that point is attributed to the stretching vibrations of C=O, C=C, and CN. Characteristic peaks of OQD also appear in OQD / rGO-0.5, such as... Figure 3 As shown in b, the C=N stretching vibration of the OQD results in a vibration at 1565 cm⁻¹. -1 A distinct characteristic peak appears at this point. Furthermore, C=C exhibits a slight redshift, reaching 1590 cm⁻¹. -1 This indicates that there is a strong π-π interaction between OQD and rGO.

[0014] 3. Ultraviolet-Vis (UV-vis) absorption spectrum To further verify the synthesis of OQD molecules, the UV-Vis absorption spectra of QD and OQD samples are as follows: Figure 4 As shown in Figure a, in the UV-vis spectrum of QD, the absorption peak in the 200-400 nm band (295 nm) is attributed to the π-π* transition of benzene ring and quinone molecules, while the absorption peaks at 513 and 549 nm are characteristic absorption peaks of the QD unit. The UV-vis spectrum of OQD molecules differs from that of OQ molecules. In OQD, the absorption peak at 216 nm is attributed to the n-π* transition of C=N, the absorption peak at 252 nm can be attributed to the π-π* transition of benzene ring, and the absorption peak at 288 nm is attributed to the π-π* transition of quinone molecules. In particular, a strong absorption peak appears at 438 nm, which may be a characteristic absorption peak of OQD molecules. The absorption peak at 556 nm is a characteristic absorption peak of QD units, and this absorption peak shows a significant red shift because OQD molecules have a more complete π-conjugated structure.

[0015] 5. Raman spectroscopy analysis The degree of graphitization of rGO, QD / rGO, and OQD / rGOs was evaluated using Raman spectroscopy, such as... Figure 4 As shown in b, the Raman spectra of all samples show two distinct characteristic peaks: 1343 cm⁻¹. -1 The D peak at 1588 cm⁻¹ indicates the degree of disorder and defects in the graphite structure; -1 The G peak at that location represents sp 2In-plane stretching vibrations of carbon. I D / I G The ratio is typically a standard indicator for assessing the degree of graphitization in materials. It is worth noting the I values ​​for QD / rGO-0.5, OQD / rGO-0.3, OQD / rGO-0.5, and OQD / rGO-1. D / I G The values ​​were 0.994, 1.021, 1.020, and 1.003, respectively, all lower than the I of rGO. D / I G The value is (1.03). These results indicate that when QD and OQD molecules are modified onto the rGO surface, the sp conjugated with graphite... 2 Molecules with parallel network orientation can reduce the degree of disorder and defects in graphene to some extent.

[0016] III. Electrochemical Performance 1. Electrochemical performance of organic molecular electrodes Preparation of the working electrode in the three-electrode system: Electrochemically active material (OQD / rGO) and acetylene black were uniformly mixed at a mass ratio of 40:7. 0.4 mL of 0.25 wt% Nafion solution was added to the thoroughly mixed material and dispersed uniformly using ultrasound. The resulting suspension (6 μL) was dropped onto a glassy carbon electrode and allowed to air dry at room temperature.

[0017] Electrochemical performance testing: A three-electrode testing system was constructed using a glassy carbon electrode (working electrode), a platinum sheet electrode (counter electrode), and a saturated calomel electrode (SCE, reference electrode) loaded with electrochemically active materials. The electrochemical performance of the prepared organic molecular electrode was tested by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests.

[0018] We evaluated the electrochemical performance of QD, OQD molecules, and the corresponding prepared molecular electrode material OQD / rGO by designing and assembling a three-electrode system. The electrolyte used was 1 mol L⁻¹. -1 H2SO4. Figure 5 Comparing the cyclic voltammetry curves of QD and OQD, it is clear that OQD has a significant redox peak and a larger CV curve integral area, indicating better pseudocapacitive characteristics. Figure 5 b is QD and OQD in 1 A g -1 Comparing the GCD curves under different current densities, it is clear that OQD has a distinct charge / discharge plateau and better capacitance characteristics. Calculations show that at 5 mV / s... -1 The specific capacitance of OQD is 132F g. -1 The specific capacitance of QD is only 14 F g. -1This indicates that the oxidation of QD to form OQD molecules allows for a better Faraday reaction, which is related to the formation of a complete π-conjugated structure within the OQD molecule. Figure 6 The cyclic voltammetry (CV) curves for rGO, QD / rGO-0.5, and OQD / rGOs are shown. The CV curve for rGO is quasi-rectangular, indicating its double-layer capacitance characteristics. The redox peaks for QD / rGO-0.5 are not prominent, indicating that QD / rGO-0.5 has relatively low electrochemical activity. In contrast, the CV curve for OQD / rGOs shows a pair of strong and symmetrical redox peaks at +0.22 / 0.27 V, which is due to the redox reaction at C=O / C-OH within the OQD molecule. At 5 mV s... -1 At that time, the specific capacitances of rGO, QD / rGO-0.5, OQD / rGO-0.3, OQD / rGO-0.5, and OQD / rGO-1 were 164, 122, 311, 478, and 296 F g, respectively. -1 Therefore, the optimal sample ratio is OQD / rGO-0.5. Excessive OQD molecules will increase resistance and hinder electrolyte ions from entering the sample, while insufficient OQD molecules will reduce the pseudocapacitance of the composite material. Figure 6 As shown in b, the GCD curves of rGO and QD / rGO-0.5 are basically triangular, while the GCD curve of OQD / rGOs shows obvious charging and discharging plateaus, which are consistent with the redox peak potentials observed in the CV curve, further confirming that the OQD molecules undergo redox reactions.

[0019] Electrochemical impedance spectroscopy (EIS) is used to study the conductivity and ion transport properties of materials during electrochemical processes. Figure 6 c shows the Nyquist plots for all electrode materials based on a bias voltage of -0.1 V. In the low-frequency region, the Nyquist curves for all samples are nearly vertical, indicating rapid ion diffusion within the materials. OQD / rGO-0.5 exhibits a more vertical curve, suggesting lower diffusion resistance. In the high-frequency region, OQD / rGO-0.5 displays a small semicircle, indicating lower charge transfer resistance. This result is consistent with DFT calculations and is closely related to the electronic structure of the OQD molecule and its efficient binding with rGO. Figure 6 Figure d shows the specific capacitance, i.e., rate performance, of all samples at different scan rates. Clearly, OQD / rGOs exhibit higher capacitance retention compared to rGO and QD / rGO-0.5, with OQD / rGO-0.5 retaining 89.6% of its capacitance.

[0020] Figure 7Figure a compares the CV curves of pure organic molecules OQD, rGO, QD / rGO, and OQD / rGO-0.5 electrode materials. Within the potential range of -0.4 to 0.6 V, the CV curve of rGO exhibits a typical quasi-rectangular shape, while the redox peaks of QD / rGO are not prominent, indicating that QD / rGO has relatively low electrochemical activity. In contrast, OQD / rGO-0.5 shows a pair of strong and symmetrical redox peaks, which is due to the Faraday reaction occurring within the C=O / C-OH molecules of OQD. At 5 mV s... -1 At the scan rate, the specific capacitances of OQD, rGO, QD / rGO, and OQD / rGO-0.5 are 132, 164, 122, and 478 F g, respectively. -1 Clearly, the OQD / rGO-0.5 organic molecular electrode exhibits the best electrochemical performance.

[0021] Figure 7 b represents the OQD / rGO-0.5 composite electrode material with a scan rate of 5–100 mV s in the potential range of -0.4–0.6 V (vs SCE). -1 The CV curves are shown below. It is evident that the area under the CV curve of OQD / rGO increases with increasing scan rate, indicating that the OQD / rGO-0.5 composite electrode material has good rate performance.

[0022] In an acidic electrolyte, the oxidation of quinacridone involves an electrochemical process involving two electrons and two protons, and the corresponding redox reactions are shown below: Figure 7 c is the current density 1 A g -1 The GCD curves of pure organic molecules OQD and rGO, and organic molecular electrodes QD / rGO and OQD / rGO-0.5 are shown below, with a potential window from -0.4 to 0.6 V. Compared with pure OQD and rGO, OQD / rGO-0.5 exhibits a pair of clear and highly symmetrical charge-discharge plateaus on the GCD curve. This indicates that the electrochemical reaction of this composite electrode material is a rapid and reversible process. Figure 7 d represents the GCD curves of OQD / rGO-0.5 at different current densities, which show a highly symmetrical charge / discharge plateau. This behavior is consistent with the pseudocapacitive behavior of OQD / rGO-0.5 observed in the CV curves, indicating excellent reversibility.

[0023] 2. Electrochemical performance testing of asymmetric capacitors (ASC) The OQD / rGO-0.5 positive electrode material and PDQ / rGO negative electrode material were uniformly mixed with acetylene black at a mass ratio of 80:14, respectively. Then, 0.4 mL of 0.25 wt% Nafion solution was added, and the mixture was uniformly dispersed using ultrasound. Next, the positive and negative electrode mass ratios (m...) were... + / m - = 1.11:1) OQD / rGO-0.5 and PDQ / rGO were coated onto corresponding positive and negative electrode graphite papers, respectively, and air-dried at room temperature to obtain OQD / rGO-0.5 positive electrode and PDQ / rGO negative electrode. The preparation of the PDQ / rGO negative electrode material was as follows: 45 mg of GO was dispersed in 15 mL of DMF, and then 13.5 mg of PDQ (quinone-rich polymer, preparation method see the literature Synthesis and capability evaluation of quinone-enriched polymer with extended π-conjugated and contorted structures for effcient energy storage) was dissolved in 15 mL of DMF, forming a mixed solution through self-assembly. This mixed solution was placed in a 40 mL polytetrafluoroethylene-lined stainless steel autoclave for hydrothermal reduction self-assembly at 180 °C for 12 h. Finally, the product was repeatedly washed with acetonitrile, anhydrous ethanol, and double-distilled water, and the washed product was freeze-dried to obtain the PDQ / rGO negative electrode material.

[0024] Energy density ( E ) and power density ( P Energy density (ED) is a crucial parameter for evaluating the energy storage and conversion capabilities of supercapacitors. To test the actual energy storage performance of electrode materials and improve device energy density, we selected the prepared OQD / rGO-0.5 as the positive electrode and PDQ / rGO as the negative electrode to construct an asymmetric capacitor, labeled PDQ / rGO / / OQD / rGO (ASC). CV, GCD, and cycle stability tests were performed. All electrochemical tests were conducted on a CHI760E electrochemical workstation, and cycle stability was tested using a LAND battery testing system. The electrolyte used was 1 M H2SO4.

[0025] Since energy density is proportional to cell voltage (ΔV), we maximized the ΔV range and tested the CV curves of the capacitor at different operating voltages. The results showed that no hydrogen or oxygen evolution was observed in the CV curves as the operating voltage increased from 1.4 V to 1.8 V. Therefore, the operating voltage of the capacitor was determined to be 1.8 V. Figure 8 'a' represents the ASC at 0-1.8 V and a scan rate of 5-70 mVs. -1The CV curves at 0.51 V are shown in the figure. As can be seen from the figure, the ASC shows a pair of obvious redox peaks near 0.51 V, which indicates that the redox capacitance characteristics are effectively superimposed on the double-layer capacitance. When the current density increases, the shape of the CV curve changes very little, indicating that the assembled ASC has fast current potential response and charge-discharge performance.

[0026] Figure 8 b shows the GCD test results of PDQ / rGO / / OQD / rGO at different current densities. All GCD curves maintain good symmetry, indicating that the capacitor has good electrochemical reversibility. At the same time, it shows a clear charge-discharge plateau at around 0.51 V, which corresponds to the synergistic redox reaction of OQD / rGO and PDQ / rGO, consistent with the results of the CV curve.

[0027] Figure 9 Figure a shows the relationship between the energy density and power density of PDQ / rGO / / OQD / rGO (ASC). PDQ / rGO / / OQD / rGO achieves a power density of 608 W / kg at a cell voltage of 1.8 V. -1 At that time, the energy density reached 25.74 Wh / kg. -1 When the power density is 5422 W kg -1 At that time, the energy density was 12.2 Wh / kg. -1 .

[0028] Figure 9 b is PDQ / rGO / / OQD / rGO (ASC) at a current density of 3 A g -1 After 10,000 charge-discharge cycles, the capacitance retention rate was 91% and the coulombic efficiency was 96%, indicating that the ACS can still maintain stable energy storage after multiple cycles.

[0029] The utilization of supercapacitor energy storage and conversion technology is of great significance for its practical applications. Therefore, we will apply the constructed PDQ / rGO / / OQD / rGO asymmetric supercapacitor. When the two devices are connected in series, they can light up 49 LED bulbs. Figure 10 ).

[0030] In summary, this invention successfully prepared quinone-based organic molecules (OQDs) with intact intramolecular π-conjugated structures using a simple nitric acid oxidation method. Furthermore, an OQD was anchored onto a reduced graphene oxide (rGO) framework via a one-step solvothermal method, constructing an OQD / rGO organic molecular electrode material. This material is based on a non-covalent functionalization strategy, using rGO as the conductive substrate and selecting electrochemically active OQD molecules. Utilizing the interaction between the OQD's intact π-conjugated structure and the rGO surface, effective immobilization is achieved through solvothermal self-assembly, ultimately yielding a green, all-carbon organic molecular electrode material, OQD / rGO. Its actual energy storage performance was then investigated. Studies show that the redox reaction of OQD molecules on the rGO surface synergistically contributes to pseudocapacitance and double-layer capacitance, thus significantly improving the overall capacitance performance of the electrode material. Experimental results demonstrate that this organic molecular electrode exhibits good rate performance and cycling stability at 5 mV / s. -1 At the scan rate, the specific capacitance of OQD / rGO reaches 478 F g. -1 Furthermore, the asymmetric supercapacitor composed of PDQ / rGO and OQD / rGO (PQD / rGO / / OQD / rGO) exhibits excellent energy storage performance, reaching 608 W / kg. -1 The energy density reaches 25.74 Wh / kg at the power density. -1 At a current density of 3 A g -1 After 10,000 charge-discharge cycles, the capacitance retention rate is 91%, and the two devices connected in series can light up 49 LED bulbs. Attached Figure Description

[0031] Figure 1 (a) Preparation of OQD, (b) Schematic diagram of the synthesis of OQD / rGO organic molecular electrode; Figure 2 (a, b) Representative SEM images of rGO and (d, e) OQD / rGO at different magnifications; (c) Representative TEM images of rGO and (f) OQD / rGO; Figure 3 (a, b) FTIR spectra of QD, OQD, rGO, and OQD / rGO-0.5; Figure 4 (a) UV-vis spectra of QD and OQD; (b) Raman spectra of rGO and OQD / rGOs materials; Figure 5 (a) CV curves of sample QD and OQD, (b) GCD curves of sample QD and OQD; Figure 6 For OQD / rGOs electrode materials at 5 mV s -1 The CV curve under condition (a) is shown in 1 A g.-1 (b) GCD curve, (c) Nyquist curve and (d) specific capacitance at different scan rates.

[0032] Figure 7 (a) Pure OQD, rGO, QD / rGO and OQD / rGO-0.5 at a scan rate of 5 mV s -1 (a) CV curves of OQD / rGO-0.5 at different scan rates, (b) CV curves of pure OQD, rGO, QD / rGO and OQD / rGO-0.5 at 1 A g -1 The GCD curves of (d)OQD / rGO-0.5 under different current densities; Figure 8 (a) CV curves of PDQ / rGO / / OQD / rGO in 1 M H2SO4 at different scan rates; (b) galvanostatic charge-discharge curves of ASC at different current densities. Figure 9 (a) Relationship between energy density and power density of PDQ / rGO / / OQD / rGO, (b) PQD / rGO / / OQD / rGO at 3 A g -1 Cyclic stability after 10,000 cycles; Figure 10 Assembly schematic diagram of ASC and practical application of two ASCs. Detailed Implementation

[0033] The following specific embodiments further illustrate the preparation method of the oxyquinacridone / reduced graphene oxide organic molecular electrode of the present invention.

[0034] Example 1: Preparation of OQD / rGO electrode material (1) Preparation of oxidized quinacridone molecules (OQD) 300.0 mg of quinacridone (QD) was slowly added to 10 mL of concentrated HNO3 and stirred continuously for 4 h to oxidize. After the reaction was completed, the product was repeatedly centrifuged and washed with double-distilled water until neutral. The centrifuged precipitate was collected and dried under vacuum at 80 °C for 12 h to obtain orange-red OQD powder (242.0 mg, yield 80.6%).

[0035] (2) Preparation of oxyquinacridone / reduced graphene oxide organic molecular electrode (OQD / rGO) 45 mg of graphite oxide (GO) was dispersed in 15 mL of DMF and sonicated for 1 h. Next, 22.5 mg of OQD was dissolved in 15 mL of DMF and sonicated for 1 h. Then, the sonicated GO and OQD dispersions were mixed together and self-assembled to form a mixed solution, which was sonicated for another 1 h. This mixture was then placed in a 40 mL PTFE-lined stainless steel autoclave and subjected to solvothermal reduction self-assembly at 180 °C for 12 h. After natural cooling, the product was repeatedly washed with anhydrous ethanol and double-distilled water. Finally, the washed product was freeze-dried at -50 °C for 24 h to obtain the OQD / rGO organic molecular electrode material, labeled OQD / rGO-0.5 (OQD to rGO mass ratio 1:2). OQD / rGO-0.5 was tested at 5 mV / s. -1 The lower specific capacitance is 478 F g -1 .

[0036] Example 2 The only difference was that the amount of OQD added was 15 mg, while everything else remained the same as in Example 1, resulting in an OQD / rGO-0.3 ratio (OQD to rGO mass ratio 1:3). At 5 mV s -1 At that time, the specific capacitance of OQD / rGO-0.3 was 311 F g. -1 .

[0037] Example 3 The only difference was that the amount of OQD added was 45 mg, while everything else remained the same as in Example 1, resulting in OQD / rGO-1 (OQD to rGO mass ratio 1:1). At 5 mV s -1 At that time, the specific capacitance of OQD / rGO-1 was 296 F g. -1 .

[0038] Example 4: Asymmetric Supercapacitor Using the OQD / rGO-0.5 prepared in Example 1 as the positive electrode and PDQ / rGO as the negative electrode, an asymmetric supercapacitor (PDQ / rGO / / OQD / rGO) was assembled. The PDQ / rGO / / OQD / rGO achieved a power density of 608 W / kg at a cell voltage of 1.8 V. -1 At that time, the energy density reached 25.74 Wh kg. -1 When the power density is 5422 W kg -1 At that time, the energy density was 12.2 Wh kg. -1 PDQ / rGO / / OQD / rGO (ASC) at a current density of 3 A g -1 After 10,000 charge-discharge cycles, the capacitance retention rate is 91% and the coulombic efficiency is 96%.

Claims

1. A method for preparing an oxyquinacridone / reduced graphene oxide organic molecular electrode material, characterized in that... This includes the following steps: (1) Preparation of oxidized quinacridone: Quinacridone was added to concentrated nitric acid and stirred to oxidize it. After centrifugation, washing and vacuum drying, oxidized quinacridone powder was obtained. (2) Preparation of mixed dispersion: Graphene oxide is dispersed in DMF and sonicated, and quinacridone oxide powder is dissolved in DMF and sonicated. The two dispersions are mixed and sonicated again. (3) Solvent thermal reduction self-assembly: The mixture was placed in a high-pressure reactor and reacted at 170~185℃ for 12~14 h. After cooling, the product was washed. The washed product was freeze-dried to obtain OQD / rGO electrode material.

2. The preparation method of the oxyquinacridone / reduced graphene oxide organic molecular electrode material as described in claim 1, characterized in that: In the OQD / rGO electrode material, the mass ratio of OQD to rGO is 1:1 to 1:

3.

3. The preparation method of the oxyquinacridone / reduced graphene oxide organic molecular electrode material as described in claim 1, characterized in that: In step (1), the oxidation time of quinacridone in concentrated HNO3 is 3-5 h; the mass-to-volume ratio of quinacridone QD to concentrated nitric acid is 25-35 mg / mL.

4. The preparation method of the oxyquinacridone / reduced graphene oxide organic molecular electrode material as described in claim 1, characterized in that: In step (3), freeze drying is performed at -50~-20℃ for 12~48 h.

5. An OQD / rGO organic molecular electrode material prepared by any one of claims 1-4, characterized in that: OQD is a nitrogen-containing carbonyl compound with an intact intramolecular π-conjugated structure; OQD and rGO are non-covalently bonded through π-π interactions; the material exhibits a three-dimensional porous wrinkled structure, and at 5 mV s -1 The specific capacitance reaches 478 F g -1 .

6. The application of the OQD / rGO organic molecular electrode material as described in claim 5 as a positive electrode in supercapacitors.

7. An asymmetric supercapacitor, characterized in that: The positive electrode is the OQD / rGO material as described in claim 5; the negative electrode is a quinone-rich polymer-modified reduced graphene oxide PDQ / rGO material.

8. The asymmetric supercapacitor as described in claim 7, characterized in that: At a cell voltage of 1.8 V, the power density is 608 W kg. -1 At that time, the energy density reached 25.74 Wh kg. -1 When the power density is 5422 W kg -1 At that time, the energy density was 12.2 Wh kg. -1 ; in 3 A g -1 After 10,000 cycles at current density, the capacitance retention is ≥91% and the coulombic efficiency is ≥96%.

Images