Preparation method and application of ganoderma lucidum porous carbon loaded metal oxide

Abstract

The invention discloses a lucid ganoderma porous carbon loaded metal oxide, which is characterized in that lucid ganoderma porous carbon is used as a carrier, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dehydrate and urea are used as raw materials, and through hydrothermal reaction and calcination, the lucid ganoderma porous carbon loaded metal oxide NiMoO4 / CoMoO4-CGL, named as NMO / CMOS-CGL for short, can be prepared. The NMO / CMOS-CGL is composed of amorphous carbon, CoMoO4 (CoMoO4) and NiMoO4 (NiMoO4); according to the microstructure, a nanosphere structure exists in a honeycomb porous structure, and the nanosphere structure is CoMoO4 and NiMoO4. And the specific surface area is 275-285 m < 2 > g <-1 >. The preparation method comprises the following steps: 1, preparing a lucid ganoderma porous carbon loaded metal precursor; and 2, preparing the ganoderma lucidum porous carbon loaded metal oxide. According to the application of the material as a supercapacitor electrode material, when the current density is 1A g <-1 >, the value of the specific capacitance is 802-812F g <-1 >; and when the discharge current density is 10A g <-1 > and the charge-discharge cycle number is 30000, the cycle stability is kept to be 93%-94% of the initial specific capacitance.

Description

Technical Field

[0001] The invention relates to the technical field of supercapacitor electrode materials, and in particular to a preparation method and application of ganoderma porous carbon loaded with metal oxides. Background Art

[0002] Supercapacitors can be divided into electric double layer capacitors (EDLCs), pseudocapacitors and hybrid supercapacitors according to the charge storage mechanism. Among them, the main active materials in pseudocapacitors are transition metal oxides (TMOs). Prior art shows that multi-metal oxides have higher charge transfer efficiency than single metal oxides, and thus have higher electrochemical performance. Among multi-metal oxides, MMoO4 (M = Co, Ni) has a higher theoretical specific capacitance and rich redox reactions. For example, existing literature 1 (Mao-Cheng Liu, Ling-Bin Kong, et al. Design and synthesis of CoMoO4-NiMoO4·xH2O bundles with improved electrochemical properties for supercapacitors, Journal of Materials Chemistry A, 2013, 1380-1387.) synthesized CoMoO4-NiMoO4 with a rod-like structure as an electrode material, and obtained a current density of 2.5 mA cm -2 When the specific capacitance is 1039F g -1 However, when the current density increases 10 times, the specific capacity retention rate is only 72.3%, that is, the cycle stability is poor. The reason is that metal oxides have serious volume expansion problems during the electrochemical reaction, which significantly reduces their cycle life.

[0003] In order to improve the cyclic stability of multi-metal oxides, the dispersibility and stability of the active material can be improved by introducing a carrier. Among the common carrier materials, carbon materials, such as graphene GO, reduced graphene oxide rGO, carbon nanotubes CNTs, metal-based foams and MXene, in addition to the aforementioned functions of improving dispersibility and stability, also have the function of improving the conductivity of the composite material, which can further improve the electrochemical performance of the composite material. For example, the previous research results of the research group of the inventor of the present invention, the existing document 2 (CN 115312328 A, Zou Yongjin, Tian Zhiwei, etc., a SDS-treated mangosteen shell-based porous carbon-loaded Ni-Co-O nanoparticle material and its preparation method and application, 2022) SDS-treated mangosteen shells were used to synthesize porous carbon-loaded Ni-Co-O nanoparticle materials to prepare a composite material composed of porous carbon and Ni and Co oxides. Among them, the porous carbon material prepared from mangosteen shells is used as a carrier, and the oxides of Ni and Co are active substances. The micromorphology of the obtained composite material presents a nano-needle-like porous structure. When used as a supercapacitor, at a current density of 1Ag -1 When the specific capacitance reaches 890-900F g -1 ; The specific capacitance after 5000 charge and discharge cycles remains at 80-81% of the initial specific capacitance. This technical solution uses the surfactant SDS to modify the porous carbon material derived from the biomass mangosteen shell, thereby significantly improving the specific capacitance performance and cycle performance. Further analysis shows that the mangosteen shell-derived porous carbon material itself has fewer natural pores and cannot effectively improve the performance as a carrier, so SDS needs to be used for modification. It is precisely because of the above reasons that this technical solution has the technical problem of complex preparation process.

[0004] Similar technical solutions based on biomass carbon materials are also available in the existing literature 3 (Fu, M., Zhu, Z., et al. Microwave assisted growth of MnO2 on biomass carbon for advanced supercapacitor electrode materials. J Mater Sci 56, 2021, 6987-6996.). This technical solution uses passion fruit peel to prepare carbon materials, and then loads MnO2 through microwave assisted growth to achieve granular MnO2 distribution on the carbon material, obtaining a current density of 1Ag -1 When the specific capacitance is 616.3F g -1 , and, at 10Ag -1The technical effect is that the capacitance retention rate after 20,000 cycles is 95.3% at a current density of . By comparing with the existing document 2, it can be seen that this technical solution does not modify the biomass-derived carbon material. Although it avoids the cumbersome preparation process, it actually reduces the necessary technical features and fails to achieve the technical effect of regulating the micromorphology of the passion fruit peel-derived carbon material, resulting in the obtained carbon material not having the technical feature of a porous structure, and ultimately resulting in the agglomeration of the introduced metal oxides, which cannot effectively improve the electrochemical performance.

[0005] In order to achieve the reduction modification operation and obtain carbon materials with specific micromorphology at the same time, materials with specific micromorphology can be used as basic raw materials. For example, existing document 4 (Xingmei Guo, Wei Zhang, et, al. MnO2 / C composite with 3D hierarchical architecture for high-performance supercapacitor electrodes, Ceramics International, 2018, 9696-9702.) uses the natural porous network structure of butterfly wings, and after heteroatom doping, nano-spherical MnO2 is loaded through a carbonization-surface reaction process, and evenly distributed on the surface of the carrier obtained from the carbon material. A current density of 1Ag was achieved. -1 When the specific capacitance is 1539.7Fg -1 , and at 10Ag -1 The technical effect is that the capacitance retention rate is as high as 97.6% after 10,000 cycles at a current density of . However, the morphology of the obtained composite material is not uniform, and the loaded MnO2 is unevenly distributed. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method and application of Ganoderma lucidum porous carbon loaded with metal oxides. Ganoderma lucidum originally has a specific microscopic morphology, and when prepared into porous carbon, a microscopic morphology with coexistence of micropores and mesopores can be formed, which can be used as a carrier of supercapacitor material to load metal oxides.

[0007] Among them, the role of Ganoderma porous carbon is to increase the contact area with electrolyte ions, thereby increasing the ion diffusion rate, thereby improving conductivity and stability;

[0008] The role of the metal oxides CoMoO4 and NiMoO4 is to provide pseudocapacitance.

[0009] The specific technical solution for achieving the purpose of the present invention is:

[0010] A ganoderma porous carbon supported metal oxide, using ganoderma porous carbon as a carrier, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea as raw materials, through hydrothermal reaction and calcination, ganoderma porous carbon supported metal oxide NiMoO4 / CoMoO4-CGL, referred to as NMO / CMO-CGL;

[0011] The NMO / CMO-CGL is composed of amorphous carbon, CoMoO4 and NiMoO4;

[0012] The microscopic morphology of the NMO / CMO-CGL is a honeycomb porous structure with a nanosphere structure, wherein the nanosphere structure is CoMoO4 and NiMoO4;

[0013] The specific surface area of ​​the NMO / CMO-CGL is 275-285m 2 g -1 .

[0014] A method for preparing a ganoderma porous carbon loaded with metal oxides comprises the following steps:

[0015] Step 1, preparation of a ganoderma porous carbon supported metal precursor, first, placing the ganoderma porous carbon CGL in deionized water, and performing ultrasonic dispersion to obtain solution A, then placing nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea in solution A to satisfy a certain molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea to obtain a reaction solution, and finally, under certain conditions, subjecting the reaction solution to a hydrothermal reaction, and after the reaction is completed, washing and drying the obtained product to obtain a ganoderma porous carbon supported metal precursor, referred to as NiMoCo-CGL;

[0016] In step 1, the conditions for preparing solution A are as follows: the ultrasonic time is 20-30 min;

[0017] In the step 1, the nickel nitrate hexahydrate, the cobalt nitrate hexahydrate, the sodium molybdate dihydrate and the urea satisfy a molar ratio of 1:3:2:10;

[0018] In the step 1, the conditions of the hydrothermal reaction are: the hydrothermal temperature is 120° C., and the hydrothermal time is 12 h;

[0019] Step 2, preparation of Ganoderma porous carbon supported metal oxides, under certain conditions, calcining the NiMoCo-CGL obtained in step 1 to obtain Ganoderma porous carbon supported metal oxides NiMoO4 / CoMoO4-CGL, referred to as NMO / CMO-CGL.

[0020] In the step 2, the calcination conditions are: in air, the calcination temperature is 400° C., and the calcination time is 2 hours.

[0021] Application of Ganoderma lucidum porous carbon loaded with metal oxides as supercapacitor electrode materials, when the current density is 1A -1 When the specific capacitance is 802-812F g -1 ;

[0022] At a discharge current density of 10A -1 When the number of charge and discharge cycles reached 30,000, the cycle stability remained at 93%-94% of the initial specific capacitance.

[0023] The beneficial technical effects of the present invention have been tested experimentally, and the results are as follows:

[0024] XRD test showed that NMO / CMO-CGL was composed of amorphous carbon, CoMoO4 and NiMoO4;

[0025] SEM test showed that NMO / CMO-CGL showed a honeycomb porous structure with nanospheres;

[0026] The BET test shows that the specific surface area of ​​NMO / CMO-CGL is 275-285m 2 g -1 ;

[0027] According to the electrochemical test, when the current density is 1A -1 When the specific capacitance is 802-812F g -1 ; At a discharge current density of 10Ag -1 , when the number of charge and discharge cycles reached 30,000, the cycle stability remained at 93-94% of the initial specific capacitance.

[0028] Therefore, the present invention has the following advantages over the prior art:

[0029] 1. The preparation method of the present invention is a one-step hydrothermal method, which has the advantages of simple process and low cost;

[0030] 2. Ganoderma porous carbon significantly improves the electrochemical performance and stability of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 XRD test curves of NMO / CMO-CGL, NMO / CMO-FG and NMO / CMO prepared in Example 1, Comparative Example 1 and Comparative Example 2;

[0032] Figure 2 is the SEM image of CGL in Example 1;

[0033] Figure 3is the SEM image of NMO / CMO-CGL in Example 1;

[0034] Figure 4 It is the SEM image of NMO / CMO in Comparative Example 1;

[0035] Figure 5 is the SEM image of NMO / CMO-FG in Comparative Example 2;

[0036] Figure 6 The constant current charge and discharge curves of NMO / CMO-CGL at different current densities in Example 1;

[0037] Figure 7 The constant current charge and discharge curves of NMO / CMO at different current densities in Comparative Example 1;

[0038] Figure 8 The constant current charge and discharge curves of NMO / CMO-FG at different current densities in Comparative Example 2;

[0039] Fig. 9 The NMO / CMO-CGL and NMO / CMO in Comparative Example 2 were respectively combined with activated carbon to form an asymmetric supercapacitor at a current density of 10A. -1 The cycle performance diagram below. DETAILED DESCRIPTION

[0040] The present invention is further described in detail through embodiments and in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0041] Example 1

[0042] A method for preparing a ganoderma porous carbon loaded with metal oxides comprises the following steps:

[0043] Step 1, preparation of a ganoderma porous carbon-supported metal precursor, first, placing 4 mg of ganoderma porous carbon CGL in 20 mL of deionized water, and performing ultrasonic dispersion with an ultrasonic time of 20 min to obtain solution A, then placing nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea in solution A with a molar ratio of 1:3:2:10 to obtain a reaction solution, and finally, performing a hydrothermal reaction on the reaction solution at a hydrothermal temperature of 120° C. and a hydrothermal time of 12 h. After the reaction is completed, washing and drying the obtained product to obtain a ganoderma porous carbon-supported metal precursor, referred to as NiMoCo-CGL;

[0044] Step 2, preparation of Ganoderma porous carbon loaded with metal oxides, calcining the NiMoCo-CGL obtained in step 1 under air conditions at a calcination temperature of 400°C and a calcination time of 2h to obtain Ganoderma porous carbon loaded with metal oxides NiMoO4 / CoMoO4-CGL, referred to as NMO / CMO-CGL.

[0045] In order to prove the composition of NMO / CMO-CGL, XRD test was carried out, and at the same time, XRD test was carried out on CGL for comparison.

[0046] The test results of CGL are as follows Figure 1 As shown, CGL has characteristic peaks of amorphous carbon;

[0047] The test results of NMO / CMO-CGL are as follows Figure 1 As shown, NMO / CMO-CGL has characteristic peaks of CoMoO4 and NiMoO4 in addition to the characteristic peaks of amorphous carbon;

[0048] The test results showed that the metal oxide NMO / CMO was successfully loaded on the Ganoderma lucidum porous carbon material, which proved that NMO / CMO-CGL was successfully prepared.

[0049] In order to verify the microstructure of NMO / CMO-CGL, SEM test was performed. Meanwhile, for comparison, SEM test was performed on CGL.

[0050] The test results of CGL are as follows Figure 2 As shown, the microstructure of CGL is a honeycomb porous structure;

[0051] The test results of NMO / CMO-CGL are as follows Figure 3 As shown, the microstructure of NMO / CMO-CGL is a honeycomb porous structure with nanosphere structure. Combined with the XRD test results, it can be seen that the nanosphere structure is CoMoO4 and NiMoO4;

[0052] The test results show that the metal oxide NMO / CMO with nanosphere structure is in situ grown on CGL. The nanosphere structure can provide abundant ion channels and shorten the transmission distance of electrolyte ions.

[0053] In order to further prove the structural characteristics of NMO / CMO-CGL, BET test was performed. The test results are shown in Table 1. The specific surface area of ​​NMO / CMO-CGL is 275m 2 g -1 .

[0054] Table 1 Specific surface area and average pore size of comparative example 1 and embodiment 1

[0055] sample <![CDATA[Specific surface area (m 2 g -1 )]]> Average pore size (nm) Example 1 275 2.1 Comparative Example 1 189 2.4

[0056] In order to prove the electrochemical performance of NMO / CMO-CGL as a supercapacitor electrode material, the specific capacity test under constant current charge and discharge at different rates was carried out. The test results are shown in Table 2 and Figure 6 As shown, when the current density is 1A g -1 When NMO / CMO-CGL has a specific capacitance of 802 F g -1 .

[0057] Table 2 Specific capacitance values ​​of composite materials prepared on different carbon substrates

[0058] sample Carbon substrate <![CDATA[Specific capacitance (F g -1 )]]> Example 1 Ganoderma Porous Carbon 802 Comparative Example 1 Flake graphite 653 Comparative Example 2 none 613

[0059] The cyclic stability test results of NMO / CMO-CGL are as follows: Fig. 9 As shown, at a discharge current density of 10A g -1 When the number of charge and discharge cycles reached 30,000, the cycle performance remained at 93.2% of the initial specific capacitance.

[0060] In order to demonstrate the effect of different carbon-based materials, namely carriers, on the performance, comparative example 1 is provided, in which flake graphite FG is used as a carrier to prepare metal oxides supported on flake graphite; at the same time, for comparison, a reference example, carrier-free metal oxide NMO / CMO, is provided.

[0061] Reference ratio

[0062] A method for preparing a carrier-free metal oxide NMO / CMO, wherein the steps not specifically described are the same as those in Example 1, except that: in the step 1, CGL is not added, and the obtained material is referred to as NMO / CMO.

[0063] In order to prove the composition of NMO / CMO, XRD test was carried out. The test results are as follows Figure 1 As shown, NMO / CMO has characteristic peaks of NiMoO4 and CoMoO4. The test results show that the metal oxide NMO / CMO is successfully prepared.

[0064] In order to verify the microstructure of NMO / CMO, SEM test was performed. The test results are shown in Figure 4 As shown, NMO / CMO presents a nanosphere structure. Compared with Example 1, it can be seen that when CGL is used as a carrier, the overall microscopic morphology of the composite material is changed, and the corresponding technical effects are reflected in two aspects: first, providing growth sites for NMO / CMO, and second, expanding the contact area between the electrolyte and the composite material.

[0065] In order to prove the electrochemical performance of NMO / CMO as supercapacitor electrode materials, the specific capacity test under constant current charge and discharge at different rates was carried out. The test results are shown in Table 2 and Figure 7 As shown, when the current density is 1A g -1 When NMO / CMO has a specific capacitance of 613F g -1 Compared with Example 1, it can be seen that when CGL is used as a carrier, the specific capacitance can be significantly improved, with an increase of 22.2%.

[0066] The cyclic stability test results of NMO / CMO are as follows: Fig. 9 As shown, at a discharge current density of 10A -1 When the charge-discharge cycle is 30,000, the cycle performance of NMO / CMO is only 74.4%. Compared with Example 1, the cycle performance of NMO / CMO-CGL is better, and the performance improvement is 25.2%.

[0067] By comparing Example 1 with the reference example, it can be seen that introducing CGL as a carrier can change the overall microscopic morphology of the composite material, thereby significantly improving the electrochemical performance and cycle stability.

[0068] Comparative Example 1

[0069] A preparation method based on flaky graphite loaded metal oxide, the steps not specifically described are the same as those in Example 1, except that: in step 1, the Ganoderma lucidum porous carbon is replaced with flaky graphite for hydrothermal reaction, and the obtained material is referred to as NMO / CMO-FG.

[0070] In order to prove the composition of NMO / CMO-FG, XRD test was carried out. The test results are as follows Figure 1 As shown, NMO / CMO-FG has characteristic peaks of CoMoO4, NiMoO4 and graphite. The test results show that the metal oxide NMO / CMO is successfully loaded on the flake graphite material, proving that NMO / CMO-FG is successfully prepared.

[0071] In order to verify the microstructure of NMO / CMO-FG, SEM test was performed. The test results are shown in Figure 5 As shown in the figure, the microscopic morphology of NMO / CMO-FG is a sheet-like structure with a nanosphere structure on the surface. Combined with the XRD test results, it can be seen that the nanosphere structure is CoMoO4 and NiMoO4. The test results show that only the metal oxide NMO / CMO with a nanosphere structure is in situ grown on the FG surface.

[0072] Compared with the reference sample, it can be seen that when FG is used as a carrier, the overall microscopic morphology of the composite material can also be changed;

[0073] Compared with Example 1, it can be seen that when CGL is used as a carrier, NMO / CMO can not only grow on the carbon material, but also grow inside the carbon material; the corresponding technical effect is reflected in that NMO / CMO-CGL has more ion transmission channels than NMO / CMO-FG, thereby improving the contact between electrolyte ions and NMO / CMO.

[0074] In order to further prove the structural characteristics of NMO / CMO-FG, BET test was performed on NMO / CMO-FG. The test results are shown in Table 1. The specific surface area of ​​NMO / CMO-FG is 189m 2 g -1 Compared with Example 1, it can be seen that when CGL is used as a carrier, the specific surface area can be significantly increased, with an increase of 45.5%.

[0075] In order to prove the electrochemical performance of NMO / CMO-FG as a supercapacitor electrode material, the specific capacity test under constant current charge and discharge at different rates was carried out. The test results are shown in Table 2 and Figure 8 As shown, when the current density is 1A -1 When NMO / CMO-FG has a specific capacitance of 653 F g -1 .

[0076] Compared with the reference, it can be seen that when CF is used as a carrier, the specific capacitance performance is not improved, but decreased;

[0077] Compared with Example 1, it can be seen that when CGL is used as a carrier, the specific capacitance can be significantly improved by 31.5%;

[0078] By comparing Example 1, the reference example and the comparative example 1, it can be seen that introducing carbon material as a carrier and changing the microscopic morphology of the composite material does not necessarily achieve the technical effect of significantly improving the specific capacitance performance. Combined with the SEM test and BET test results, it can be seen that when CGL is used as a carrier, NMO / CMO can grow simultaneously inside and on the surface of the carbon material, thereby achieving a significant increase in the specific surface area, and ultimately significantly improving the specific capacitance performance.

Claims

1. A Ganoderma lucidum porous carbon loaded with metal oxides, characterized in that: Taking Ganoderma porous carbon as a carrier, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea as raw materials, through hydrothermal reaction and calcination, Ganoderma porous carbon supported metal oxide NiMoO4 / CoMoO4-CGL, referred to as NMO / CMO-CGL, can be prepared; The NMO / CMO-CGL consists of amorphous carbon, CoMoO4 and NiMoO4.

2. The Ganoderma lucidum porous carbon loaded with metal oxide according to claim 1, characterized in that: The microscopic morphology of the NMO / CMO-CGL is a honeycomb porous structure with a nanosphere structure, wherein the nanosphere structure is CoMoO4 and NiMoO4.

3. The Ganoderma lucidum porous carbon loaded with metal oxide according to claim 1, characterized in that: The specific surface area of ​​the NMO / CMO-CGL is 275-285m 2 g -1 .

4. A method for preparing a Ganoderma lucidum porous carbon loaded with metal oxides, characterized in that The following steps are involved: Step 1, preparation of a ganoderma porous carbon supported metal precursor, first, placing the ganoderma porous carbon CGL in deionized water, and performing ultrasonic dispersion to obtain solution A, then placing nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea in solution A to satisfy a certain molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea to obtain a reaction solution, and finally, under certain conditions, subjecting the reaction solution to a hydrothermal reaction, and after the reaction is completed, washing and drying the obtained product to obtain a ganoderma porous carbon supported metal precursor, referred to as NiMoCo-CGL; Step 2, preparation of Ganoderma porous carbon supported metal oxides, under certain conditions, calcining the NiMoCo-CGL obtained in step 1 to obtain Ganoderma porous carbon supported metal oxides NiMoO4 / CoMoO4-CGL, referred to as NMO / CMO-CGL.

5. The preparation method according to claim 4, characterized in that: In step 1, the molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, sodium molybdate dihydrate and urea is 1:3:2:

10.

6. The preparation method according to claim 4, characterized in that: In step 1, the conditions for preparing solution A are as follows: the ultrasonic time is 20-30 min; In the step 1, the conditions of the hydrothermal reaction are: the hydrothermal temperature is 120° C., and the hydrothermal time is 12 h.

7. The preparation method according to claim 4, characterized in that: In the step 2, the calcination conditions are: in air, the calcination temperature is 400° C., and the calcination time is 2 hours.

8. The Ganoderma lucidum porous carbon loaded with metal oxide according to claim 1, characterized in that: As a supercapacitor electrode material, when the current density is 1A -1 When the specific capacitance is 802-812F g -1 .

9. The Ganoderma lucidum porous carbon loaded with metal oxide according to claim 1, characterized in that: As a supercapacitor electrode material, it can be used at a discharge current density of 10A g -1 When the number of charge and discharge cycles reached 30,000, the cycle stability remained at 93%-94% of the initial specific capacitance.

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