LU509305B1 - A preparation method and application of a co3o4@nico2o4 catalyst - Google Patents

Abstract

The invention relates to the technical field of electrocatalysis, in particular to a preparation method and application of a Co3O4@NiCo2O4 catalyst, which comprises the following steps: S1: Preparing Co3O4 nanowire layer by weighing CoCl2-6H2O, NH4F and urea; S2: NiCl2-6H2O, CoCl2-6H2O, NH4F, urea and the Co3O4 nanowire layer obtained by Step S1 are weighed, and Co3O4@NiCo2O4 catalyst is prepared. The Co3O4@NiCo2O4 nanowire layered array prepared by the invention exhibits A surprisingly high specific capacitance (1466 F g⁻¹ at 2.5 A g⁻¹), which is far superior to the traditional capacitor materials. This high specific capacitor is mainly due to its unique layered heterostructural design, which provides a wide range of surface areas and electrochemically active sites, enhancing the diffusion and charge storage capacity of electrolyte ions. Drawing 1

Description

A Preparation Method and Application of A Cos04@NiCo204 Catalyst -Y509305

Technical Field

The invention relates to the technical field of electrocatalysis, in particular to a preparation method and application of a Co304@Ni1Co0204 catalyst.

Background Technology

In recent years, with the growing demand for sustainable clean energy, the development of efficient energy storage systems has attracted much attention.

High-performance energy storage devices are an important part of clean energy technology and indispensable for next-generation electronics, biomedical devices and hybrid electric vehicles. Compared to other conventional energy storage devices, supercapacitors (also known as electrochemical capacitors) are well suited for numerous applications that require high energy density and fast charge and discharge rates, such as hybrid electric vehicles and industrial equipment. However, the low energy density of supercapacitors limits their practical applications, making them unable to meet commercial needs. Therefore, it is very important to prepare electrocatalyst which is an efficient electrode material with excellent electrochemical properties. According to previous studies, building structurally unique electrode materials for pseudo-capacitors has also proved to be a very effective way to increase energy density. The ideal electrode material should have high conductivity to promote electron transport, rich electrochemical active sites to improve specific capacitance, and be environmentally friendly. Among many materials, Co304 nanomaterials are widely considered to be the most promising catalyst materials for solar cells.

The construction of three-dimensional layered nanostructures based on Co304 on conductive substrates is still an inherent property of Co304 on conductive substrates. This can improve weaknesses and improve electrochemical performance. Heterostructures can provide a larger specific surface area and multiple accessible electroactive sites, thus facilitating electron transport and ion diffusion. Flectron transfer and ion diffusion enhance the redox reaction. For example, Sun and collaborators fabricated core-shell CosO4@NiCo204 composités’>09305 on nickel foam to achieve high specific capacitance at a current of 1514 F-g"!. The current density is 1 A g'. To date, controllable fabrication of layered arrays of bimetallic oxide nanowire with ideal surface area and porosity on nickel foam (NF) remains a major challenge for researchers designing highly efficient electrocatalysts for supercapacitors. Efficient electrocatalysts for supercapacitors remain a major challenge for researchers.

Contents of Invention

The invention aims to provide a preparation method and application of

Co0304@NiC0204 catalyst, and provides a self-supporting Co304@NiCo0204 nanowire laminated array as a high efficiency electrocatalyst, and is used as a high performance supercapacitor electrocatalyst material. This method provides a new strategy for the development of advanced electrode materials.

In order to realize the technical purpose and achieve the technical effect, the invention is realized through the following technical schemes:

A method for preparing Co304@NiC0,04 catalyst comprises the following steps:

S1: Co304 nanowire layer is prepared by weighing CoCl»-6H:0, NH4F and urea;

S2: NiCl»-6H20, CoCl-6H>O, NH4F, urea and the Co304 nanowire layer obtained by step S1 are weighed, and Co304(@N1Co2O4 catalyst is prepared.

Further, the step S1 specifically comprises the following sub-steps:

S1.1: Weighing 1.5mmol CoCl»-6H20, Immol NH4F and 2mmol urea into 40mL HO and stirring them for 20 minutes;

S1.2: The evenly stirred solution is transferred to a 50mL polytetrafluoroethylene reactor, which is filled with 2emx3em nickel foam that had been pre-treated in 6M HCI and reacted at 120 °C for 6 hours;

S1.3: Samples obtained by washing with deionized water and anhydrous/>09505 ethanol several times; After drying under vacuum at 60 °C, and then calcination at °C min’! to 300 °C for 2 hours, Co3O4 nanowire layer is obtained.

Further, the step S2 specifically comprises the following sub-steps: 5 S2.1: 0.1mmol NiCl;-6H,O, 0.2mmol CoCl;-6H,O, 0.1lmmol NH4F and 0.2mmol urea are accurately weighed and added into 40mL H»O, stirring them for 20 minutes;

S2.2: The homogenized solution is transferred to a 50mL polytetrafluoroethylene reactor, in which foamed nickel coated Co304 nanowires are added and reacted at 120 °C for 6 hours;

S2.3: After the reaction, the sample obtained by washing with deionized water and anhydrous ethanol several times; Finally, the washed sample is dried under vacuum at 60 °C, and then calcined at 5 °C-min”! to 300 °C for 2 hours to obtain

Co304(@NiCo204 catalyst.

On the other hand, the invention provides the application of the

Co304(@NiCo:O4catalyst in the preparation of supercapacitors.

The invention has the following beneficial effects:

The Co304(@NiCo204 nanowire layered array prepared by the invention exhibits A surprisingly high specific capacitance (1466 F g' at 2.5 A g'), which is far superior to the traditional capacitor materials. This high specific capacitor is mainly due to its unique layered heterostructural design, which provides a wide range of surface areas and electrochemically active sites, enhancing the diffusion and charge storage capacity of electrolyte ions. The composite containing Co304 and NiCo204 improves the kinetic properties of the redox reaction through synergistic action, thus significantly improving the capacitive properties.

Co304(@N1Co204 The nanowire array can maintain a specific capacitance of 93.8% after 5000 charge and discharge cycles, showing excellent cycle stability.

This performance is due to the high structural stability of the prepared materials, and the heterostructures are able to maintain strong mechanical strength in repeated electrochemical processes such as redox reactions and ion exchange. At the santé‘°0°805 time, the introduction of NiCo»O4 not only enhances the conductivity of the material, but also improves the chemical stability, thus reducing the material degradation in the long-term electrochemical cycle.

Compared with pure Co304 nanowires, Co304(@N1C0204 exhibits superior electrochemical properties. It illustrates enhanced electrochemical activity at various scanning speeds and current densities, which is due to the involvement of

Ni?*/Ni** redox pairs, which expands the redox reaction range of the material, thereby increasing the charge storage capacity. In addition, the three-dimensional conductive network structure of NiCo2O4 improves the electron conduction rate, making the electrochemical reaction more efficient.

The layered nanowire arrays at CosO4@NiCo204 demonstrate low charge-transfer resistance, as verified by electrochemical impedance spectroscopy (EIS). Low charge transfer resistors benefit from the material's heterostructural design, which provides a continuous electron transport path, reducing interface impedance and energy loss. NiCo2O4 plays a role in regulating the electronic structure in this system, improving the electron density and distribution uniformity, thus accelerating the charge transfer process.

And indeed, the implementation of any product of the invention does not necessarily need to achieve all the advantages described above.

Explanation on Drawings

In order to more clearly state the technical scheme of the implementation method of the invention, the following is a brief introduction of the drawings required for the description of the implementation method. It is obvious that the drawings described below are only some implementation methods of the invention, and other drawings can be obtained according to these drawings for ordinary technicians in the field without creative labor.

Drawing 1 illustrates the XRD pattern of the sample. (a) Co304 nanowires, (b)

Co304(@N1Co204 nanowires layered array;

Drawing 2 illustrates the low-power and high-power SEM images of tH&°0°805 sample. (a, b) Co304 nanowires, (c, d) Co304(@N1Co204 nanowires layered array;

Drawing 3 illustrates TEM and HRTEM images of the sample. (a, b) Co304 nanowires, (c, d) Co304(@N1C0204 nanowires layered array; 5 Drawing 4 illustrates the EDS image of Co304 nanowire @@NiCo204 nanosheet sample.

Drawing 5 illustrates the cyclic voltammetry curve and constant current charge-discharge curve of the sample. (a, b) Co30s nanowires, (c, d)

Co0304@Ni1C0204 nanowires layered array.

Drawing 6 is a comparison diagram of the electrochemical properties of the samples. (a) CV value at 25mV s”!; (b) Charge and discharge curve at 5A g I; (c)

The functional relationship between specific capacitance and scanning rate; (d)

Specific capacitance as a function of current density.

Drawing 7 illustrates the cyclic performance and Nyquist diagram of the sample. (a) Charge and discharge 5000 times under 5A g ‘ conditions; (b) Nyquist diagram under conditions 1A g 7.

Specific Implementation Method

The following is a clear and complete description of the technical scheme in the implementation method of the invention in combination with the drawings attached to the implementation method of the invention. Obviously, the described implementation method is only a part of the implementation method of the invention, but not the whole implementation method. Based on the implementation methods of the invention, all other implementation methods obtained by ordinary technicians in the field without creative labor fall within the scope of protection of the invention.

Implementation method 1

A method for preparing a CosO04@N1C0204 catalyst described in the present implementation method comprises the following steps:

S1: Co304 nanowire layer is prepared by weighing CoCl-6HO, NH4F, arfd!509305 urea;

S2: NiClL-6H20, CoCl-6H,O, NH4F, urea and the Co304 nanowire layer obtained by step S1 are weighed, and Co304(@N1Co2O4 catalyst is prepared.

In this implementation method, step S1 specifically comprises the following sub-steps:

S1.1: Weighing 1.5mmol CoCl»-6H20, Immol NH4F and 2mmol urea into 40mL H>O and stirring them for 20 minutes;

S1.2: The homogenized solution is transferred to a 50mL polytetrafluoroethylene reactor filled with 2cmx3cm nickel foam that had been pretreated in 6M HCI and reacted at 120 °C for 6 hours.

S1.3: Sample obtained by multiple washing with deionized water and anhydrous ethanol. Finally, the washed sample is dried under vacuum at 60 °C, and then calcined at 5 °C min”! to 300 °C for 2 hours to obtain the Co304 nanowire layer.

In this implementation method, step S2 specifically comprises the following sub-steps:

S2.1:0.1mmol NiCl»-6H:0, 0.2mmol CoCl:-6H20, 0.1mmol NH4F and 0.2mmol urea are accurately weighed into 40mL HO and stirred for 20 minutes.

S2.2: The evenly stirred solution is transferred to a 50mL polytetrafluoroethylene reactor, where foamed nickel coated Co304 nanowires are added and reacted at 120 °C for 6 hours.

S2.3: Samples obtained by washing with deionized water and anhydrous ethanol several times after the reaction. Finally, the washed sample is dried under vacuum at 60 °C, and then calcined at 5°C-min”! to 300 °C for 2 hours to obtain

Co304(@N1C0204 catalyst.

On the other hand, the invention provides the application of the

Co304@Ni1C0204 catalyst in the preparation of supercapacitors.

Implementation method 2

Synthesis of Co304 nanowire arrays LU509305

Weighing 1.5mmol CoCl»-6H:0, Immol NH4F and 2mmol urea into 40mL

H20 and stirring them for 20 minutes. The evenly stirred solution is transferred to a 50mL polytetrafluoroethylene reactor, which is filled with 2emx3em nickel foam that had been pretreated in 6M HCI and reacted at 120 °C for 6 hours. After the reaction, the samples are washed several times with deionized water and anhydrous ethanol. Finally, the washed sample is dried under vacuum at 60 °C and then calcined at 5 °C min”! to 300 °C for 2 hours.

Synthesis of Co304@NiCo204 electrocatalysts 0.1mmol NiCl»-6H:0, 0.2mmol CoCl,-6H>0O, 0.1mmol NH4F and 0.2mmol urea are accurately weighed into 40mL H>O and stirred for 20 minutes. Then, the evenly stirred solution is transferred to a 50mL polytetrafluoroethylene reactor, where foam-coated Co304 nanowires are added and reacted at 120 °C for 6 hours.

After the reaction, the samples are washed several times with deionized water and anhydrous ethanol. Finally, the washed sample is dried under vacuum at 60 °C and then calcined at 5 °C min”! to 300 °C for 2 hours.

Representation

The phase purity of the sample is characterized by X-ray powder diffraction with graphite monochromator and high intensity CuKa radiation (\=0.154060 nm).

The scanning speed is 8° min‘! and the scanning range is 10° to 80°. The samples are analyzed using a Hitachi S-4800 field emission scanning electron microscope (accelerated voltage 5.0kV).

The electrochemical properties of an electrocatalyst Co304(@NiCo204, in particular its specific capacitance (Csp), are calculated by the following formula:

Cp = fdr fav

S-AV-m oo A m: AV

I 1s the current density of constant current charge and discharge, At is the 209% discharge time, m is the sample quality, AV is the potential window, and S is the scanning speed.

XRD-6000 X-ray powder diffractometer is used to characterize the phase purity and structure of Cos04@N1C0204 electrocatalyst. Drawing 1 (red line) illustrates the X-ray powder diffraction pattern of Co3;04@NiCo0204 nanowire layered array. Compared with the diffraction pattern of Co304 nanowire (black line), the diffraction peak intensity is slightly enhanced, but there is basically no change. The diffraction peaks (111), (220), (311), (222), (400), (422), (511), (400), (650) and (533) can be used as the characteristic peaks of the cubic phase Co304 (JCPDS: 78-1969) and the spinel phase NiCo204 (JCPDS:73-1702) . The pattern of the Co304@Ni1C0204 structure contains diffraction peaks of Co304 and NiCo2O4, indicating the presence of these two phases on the nickel foam substrate.

The shape and size of the electrocatalyst are observed by field emission scanning electron microscopy. Drawings 2a and 2b show low - and high-power scanning electron microscopy images of Co304 nanowires. The prepared Co304 nanowire array is neat and uniform. Drawings 2c and 2d show low - and high-power SEM images of the CosO4@N1C0204 nanowire layered array.

Nickel-cobalt oxide nanowires grow through Co304 nanowires. These nanowires are interconnected to form a highly porous surface morphology. Therefore, due to the presence of efficient diffusion channels, almost all layered nanowire arrays can be easily used by electrolytes to store energy. This structure greatly increases the active surface area and provides more sites for Faraday reactions, resulting in higher specific capacitance.

Drawing 4 illustrates the EDS spectrum. Drawing 4a illustrates that nickel has a weight percentage of 19.15 and an atomic percentage of 10.48. Drawings 4b and c show a uniform distribution of nickel elements. This proves the successful construction of NiCo2O4 nanowires on Co304 nanowires.

To evaluate the electrochemical capacitance performance of Cos04@NiCo20}°09805 nanowires, cyclic voltammetry (CV) is first recorded in a three-electrode system.

The Co304(@N1C0204 electrocatalyst 1s assembled into a three-electrode system with platinum electrode and standard saturated calomel electrode to measure the electrochemical properties and compare with the Co304 nanowire array. The CV curve of the sample is measured at different scanning speeds of 5 to 50 mV s”! over a voltage range of -0.1 to 0.5V. In Drawing 5a, the redox peak of Co304 nanowire is caused by Co**/Co** and Co**/Co** redox reactions:

Co,0, +OH + H,O =3C000H +e

CoOOH+OH =Co0,+H,0+e

Drawing 5c, C0304@NiCo0,04 the expansion and migration of redox peaks in the layered nanowire array are mainly due to the increase of Ni?*/Ni**reactions:

NiCo,0, +OH +H,0 = NiOOH +2CoOOH +e"

All of the electrodes showed significant redox peaks, indicating that they have

Faraday battery-like properties. Notably, the Co304@NiCo020s electrocatalyst exhibits a higher peak current density and a larger cyclic voltamogram (CV) sealing area than Co304, which indicates a stronger charge storage capacity.

According to the electrochemical calculation formula (1), the specific capacitance at different scanning speeds is calculated. At scanning speeds of 5mV sl, 10mV s, 25mV s! and 50mV s”!, the specific capacitance of Co304@NiCo204 nanowire arrays is 1895 F g!, 1723 F g!, 1518 F g' and 1239 F g!, respectively. The specific capacitance of Co3O4 nanowire arrays is 1267 F g', 1108 F g!, 941 F g”' and 715 F g'', respectively. The main reason for this limitation is that the high scanning rate limits the entry of ions into the internal microstructure of the electrode material. As a result, ion transport is limited by slow diffusion and can only use the outer surface for charge storage. With the increase of scanning speed, the specific capacitance decreases gradually. The constant current charge-discharge curves of the samples are measured in the voltage range of -0.1-0.45V at different current densities of 2.5, 5, 10 and 20 A g'!. The specific capacitance of constant current charge and discharge can be calculated according to formula (2). Drawing’20930 5d illustrates the constant current charge and discharge curve of the

C0304@Ni1Co0,04 nanowire layered array.

Drawing 6a illustrates the comparison of cyclic voltammetry curves of Co304 nanowire array and Co304@NiC0204 nanowire layered array at 25 mV s' current density. Obviously, the enclosed area of the layered nanowire array is significantly larger than that of pure C0304, indicating that the layered array has a larger area capacitance. Drawing 6b illustrates A comparison of constant current charge and discharge at a current density of 5A g.

The specific capacitance of Co0304@NiCo0,04 nanowire-layered arrays is better than that of Co304-based nanocomposites reported in the literature, such as three-dimensional Co304@Ni(OH)2(1330 F g'@2.5mA em”).

Co304@MnO-(1532.4 F g'@1 A g), CosOs@porous carbon (1307 F g'@1 A g”) and Co3sO4@NiCo204 (672 F g'@0.5 A g!). The excellent electrochemical performance of the Co304(@N1C0204 nanowire layered array in the present implementation method is due to the reasonable design and fabrication of layered heterostructures on nickel foam.

The cyclic performance of the sample is studied by conducting 5000 charge and discharge cycles at the current density of SAg-'. As shown in Drawing 7a, the specific capacitance of the Co304@NiC0204 nanowire layered array is maintained at 93.8%, while that of the Co304 nanowire array is maintained at 91.2%. The previous literature reported that Co3;O04/MnQO; had a permittivity of 93.4% after 5000 cycles and CoMnO4/Co304 had a permittivity of 90.38% after 2000 cycles.

Co304@Ni1C0204 The excellent cycling properties of layered nanowire arrays provide a solid theoretical basis for the practical application of supercapacitor electrode materials.

To further understand the fundamental behavior of the supercapacitor electrodes, the researchers performed an electrochemical impedance spectroscopy (EIS) analysis of them. The EIS has a measurement frequency range of 100kHz to

0.05Hz and an open circuit voltage of SmV. The ionic resistance of the electrolytb/502805 the inherent resistance of the active material and the contact resistance constitute the electrochemical impedance. The diameter of the quasi-semicircular fitting circle in the high frequency region represents the charge transfer resistance of the electrode material in an electrochemical system. As shown in Drawing 7b, the resistance of CoMnO4/Co304 nanowire layered arrays is lower than that of Co3O4 nanowire arrays. The lower charge transfer resistance enables the layered array to have better electrochemical performance.

In summary, the invention adopts hydrothermal method to develop an

Co304@Ni1C0204 electrocatalyst with nanowire layered array. Due to the synergistic action of Co3O4 and NiCo204, Co304(@N1Co204 nanowire layered arrays exhibit high specific capacitance of 1466 F g' and excellent cycling performance at 2.5 A gl, and can maintain 93.8% specific capacitance after 5000 charge-discharge cycles. These results indicate that Co304@N1C0204 nanowire layered arrays will be a suitable electrocatalyst for practical energy conversion devices. From a methodological point of view, the invention makes it possible to prepare a promising Co3O4@NiCo0204 pseudo-capacitor material electrocatalyst by a simple and low-cost hydrothermal method.

The above disclosed preferred implementation methods of the invention are only used to assist in the elaboration of the invention. The preferred implementation method does not elaborate on all the details and does not limit the invention to the specific implementation method. Obviously, according to the contents of this manual, many modifications and changes can be made. These implementation methods are selected and specifically described in this specification for the purpose of better explaining the principle and practical application of the invention, so that technicians in the technical field can better understand and utilize the invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims (4)

Claims LU509305

1. A method for preparing CosO04(@N1C0204 catalyst is characterized in that: It comprises the following steps: S1: Co304 nanowire layer is prepared by weighing CoCl»-6H:0, NH4F and urea; S2: NiCl»-6H20, CoCl-6H>O, NH4F, urea and the Co304 nanowire layer obtained by step S1 are weighed, and Co304(@N1Co2O4 catalyst is prepared.

2. The preparation method of CosO4(@N1Co2O4 catalyst described in Claim 1 1s characterized in that: The step S1 specifically includes the following sub-steps:

S1.1: Weighing 1.5mmol CoCl»-6H20, Immol NH4F and 2mmol urea into 40mL HO and stirring them for 20 minutes;

S1.2: The evenly stirred solution is transferred to a 50mL polytetrafluoroethylene reactor, which is filled with 2emx3em nickel foam that had been pre-treated in 6M HCI and reacted at 120 °C for 6 hours;

S1.3: Samples obtained by washing with deionized water and anhydrous ethanol several times; After drying under vacuum at 60 °C, and then calcination at 5 °C min”! to 300 °C for 2 hours, Co304 nanowire layer is obtained.

3. The preparation method of Co304(@N1C0204 catalyst described in Claim 1 is characterized in that: The step S2 specifically includes the following sub-steps:

S2.1: 0.1mmol NiCl»-6H:0, 0.2mmol CoCl;-6H,O, 0.1lmmol NH4F and

0.2mmol urea are accurately weighed and added into 40mL H»O, stirring them for 20 minutes;

S2.2: The homogenized solution is transferred to a 50mL polytetrafluoroethylene reactor, in which foamed nickel coated Co304 nanowires are added and reacted at 120 °C for 6 hours;

S2.3: After the reaction, the sample obtained by washing with deionized water and anhydrous ethanol several times; Finally, the washed sample is dried under vacuum at 60 °C, and then calcined at 5 °C-min”! to 300 °C for 2 hours to obtain Co304@NiCo204 catalyst.

4. Application of CosO4@NiCo2O4 catalyst prepared by any of the methods/°°P805 mentioned in Claim 1-3 in the preparation of supercapacitors.