CN117996094A - Ce-NiCo2O4C@Ni foam electrode and preparation method and application thereof - Google Patents

Abstract

The invention provides a Ce-NiCo ₂O₄/C@Ni foam electrode and a preparation method and application thereof, and relates to the technical field of electrode materials. According to the invention, ce-Co ₂Ni(OH)_x/NF is obtained by hydrothermally doping Ce, co and the like on foam nickel; and then mixing the dimethyl imidazole solution with Ce-Co ₂Ni(OH)_x/NF, carrying out hydrothermal treatment, and roasting to obtain the Ce-NiCo ₂O₄/C@Ni foam. The Ce-NiCo ₂O₄/C@Ni foam electrode has the characteristics of large specific surface area and good electronic conductivity, can effectively improve the rapid permeation of electrolyte and the conduction of electrons, can promote the electroreduction reaction of H ₂O₂, and greatly improves the electroreduction performance and the utilization rate of H ₂O₂.

Description

A Ce-NiCo2O4/C@Ni foam electrode and its preparation method and application

Technical Field

The present invention relates to the technical field of electrode materials, and in particular to a Ce-NiCo ₂ O ₄ /C@Ni foam electrode and a preparation method and application thereof.

Background technique

Hydrogen peroxide (H ₂ O ₂ ) is a green, environmentally friendly, renewable oxidant that is widely used in environmental remediation, fine chemicals, and the electronics industry. H ₂ O ₂ electroreduction is a two-electron process, which has better electroreduction activity than the four-electron process of O ₂ reduction and does not cause catalyst poisoning. In addition, H ₂ O ₂ is liquid at room temperature, which is convenient for storage and transportation and more suitable for oxygen-free environments such as space and underwater. Therefore, H ₂ O ₂ shows the potential to replace O ₂ as an oxidant for fuel cells. The self-decomposition problem of H ₂ O ₂ will lead to a decrease in fuel utilization, see equations (1) and (2), resulting in a decrease in the long-term operating stability of the fuel cell.

H ₂ O ₂ +2e ^- →2OH ^- (1)

2H ₂ O ₂ →2H ₂ O+O ₂ (2)

Summary of the invention

In view of this, the present invention provides a Ce-NiCo ₂ O ₄ /C@Ni foam electrode and a preparation method thereof, which are used to improve the electrochemical performance of a fuel cell. The present invention hydrothermally dopes Ce, Co and Ni on nickel foam to obtain Ce-Co ₂ Ni(OH) _x /NF; then hydrothermally mixes a dimethyl imidazole solution and Ce-Co ₂ Ni(OH) _x /NF and calcines the mixture to obtain Ce-NiCo ₂ O ₄ /C@Ni foam and Ce-NiCo ₂ O ₄ /C@Ni foam. The Ce-NiCo ₂ O ₄ /C@Ni foam electrode of the present invention has the characteristics of large specific surface area and good electronic conductivity, can effectively improve the rapid penetration of electrolyte and the conduction of electrons, can also promote the electroreduction reaction of H ₂ O ₂ , and greatly improve the electroreduction performance and utilization rate of H ₂ O ₂ .

The present invention is achieved by adopting the following technical solutions:

The present invention provides a method for preparing a Ce-NiCo ₂ O ₄ /C@Ni foam electrode, comprising the following steps:

(1) dissolving cerium nitrate, cobalt nitrate, nickel nitrate, urea and ammonium fluoride in water to obtain an electrolyte;

(2) placing nickel foam in a polytetrafluoroethylene liner, transferring the electrolyte to the polytetrafluoroethylene liner in which the nickel foam is placed, and then placing the nickel foam in a reactor and hydrothermally heating the nickel foam at 100° C. to 140° C. for 4 h to 8 h. After naturally cooling to room temperature, the nickel foam is taken out after hydrothermal treatment, and the surface is rinsed with deionized water and alcohol, and then vacuum dried to obtain Ce-Co ₂ Ni(OH) _x /NF;

(3) dissolving dimethylimidazole in a methanol solution to obtain a dimethylimidazole solution, placing the dried nickel foam in (2) in a polytetrafluoroethylene liner, transferring the dimethylimidazole solution to the polytetrafluoroethylene liner containing the dried nickel foam, placing the nickel foam in a reaction kettle, and hydroheating the nickel foam at 80° C. to 120° C. for 4 h to 6 h. After naturally cooling to room temperature, the nickel foam is taken out after the second hydrothermal treatment, and rinsed alternately with alcohol and deionized water, and dried;

(4) The nickel foam dried in step (3) is placed in a muffle furnace, heated to 300° C.-400° C. and kept warm for 1 h-3 h to obtain Ce-NiCo ₂ O ₄ /C@Ni foam.

Preferably, the mass concentrations of cerium nitrate, cobalt nitrate, nickel nitrate, urea and ammonium fluoride in the electrolyte are 1 g/L, 19.4 g/L, 9.7 g/L, 30 g/L and 14.8 g/L, respectively.

Preferably, the size of the nickel foam is 2 cm×3 cm.

Preferably, the mass concentration of the dimethylimidazole is 8 g/L-12 g/L, and the concentration of the methanol solution is 30%-70%.

Preferably, in step (3), the drying temperature is 60° C.-80° C., and the drying time is 8 h-14 h.

Preferably, the heating rate is 2°C·min ^-1 .

Preferably, the specification of the polytetrafluoroethylene liner is 50mL.

The Ce-NiCo ₂ O ₄ /C@Ni foam catalyst is a working electrode, the carbon rod is a counter electrode, and Ag/AgCl is a reference electrode.

A Ce-NiCo ₂ O ₄ /C@Ni foam electrode is prepared by the method.

An application of a Ce-NiCo ₂ O ₄ /C@Ni foam electrode, wherein the Ce-NiCo ₂ O ₄ /C@Ni foam electrode is applied in a hydrogen peroxide electroreduction reaction, comprising the following steps:

Sodium hydroxide with a concentration of 1 mol·L ^-1 to 3 mol·L ^-1 and hydrogen peroxide with a concentration of 0.3 mol·L ^-1 to 0.70 mol·L ^-1 are mixed and dissolved in water to obtain a hydrogen peroxide electrolyte; the Ce-NiCo ₂ O ₄ /C@Ni foam electrode is used as a working electrode and placed in the hydrogen peroxide electrolyte to perform an electroreduction reaction at a voltage of -0.2 to -0.8 V vs. Ag/AgCl.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention improves the conductivity by doping with Ce. Ce has two oxidation states, Ce ³⁺ and Ce ⁴⁺ , which can change the electronic structure in the transition metal oxide, help break the OO bond in H ₂ O ₂ , and further promote the occurrence of the electroreduction reaction.

2. The addition of the organic ligand dimethylimidazole in the present invention increases the specific surface area of the electrode, facilitates the contact between the electrode and the electrolyte, and improves the reaction rate. At the same time, the organic ligand dimethylimidazole forms a conductive carbon network during the carbonization process, which increases the conductivity and exposes a large number of active sites.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is the SEM characterization of Ce-Co ₂ Ni(OH) _x /NF;

Figure 2 is the XRD pattern of Ce-NiCo ₂ O ₄ /C@Ni foam;

Figure 3 is the SEM characterization of Ce-NiCo ₂ O ₄ /C@Ni foam;

FIG4 shows the chronoamperometric test of Ce-NiCo ₂ O ₄ /C@Ni foam electrode.

Detailed ways

The present invention will be further described below in conjunction with the embodiments.

Example 1

A method for preparing a Ce-NiCo ₂ O ₄ /C@Ni foam electrode, the specific steps are as follows:

1. Weigh 0.03 g Ce(NO ₃ ) ₃ ·6H ₂ O, 0.582 g Co(NO ₃ ) ₂ ·6H ₂ O, 0.291 g Ni(NO ₃ ) ₂ ·6H ₂ O, 0.9 g CO(NH ₂ ) ₂ , and 0.444 g NH ₄ F, dissolve in 30 mL deionized water, and stir well to obtain an electrolyte;

2. Take 2cm×3cm nickel foam, insert it vertically into a 50mL polytetrafluoroethylene liner, transfer the electrolyte to the polytetrafluoroethylene liner inserted with the nickel foam, and then put it into a reactor for hydrothermal treatment at 120°C for 6h. After naturally cooling to room temperature, take out the hydrothermal nickel foam, rinse the surface with deionized water and alcohol, and vacuum dry to obtain Ce-Co ₂ Ni(OH) _x /NF, as shown in Figure 1 SEM characterization of Ce-Co ₂ Ni(OH) _x /NF;

3. Weigh 1 g of dimethylimidazole and dissolve it in a 50% methanol solution, and stir it thoroughly; vertically insert the dried nickel foam in step 2 into a 50 mL polytetrafluoroethylene liner, and then transfer the dimethylimidazole solution to the polytetrafluoroethylene liner inserted with the dried nickel foam, put it into a reactor and hydroheat it at 100°C for 5 hours. After naturally cooling to room temperature, take out the nickel foam after the second hydroheating, rinse it alternately with alcohol and deionized water, and vacuum dry it at 60°C for 12 hours.

The nickel foam dried in step 3 was placed in a muffle furnace and heated to 350°C at a heating rate of 2°C/min and kept for 2 hours to obtain Ce-NiCo ₂ O ₄ /C@Ni foam, as shown in the XRD pattern of Ce-NiCo ₂ O ₄ /C@Ni foam in FIG2 and the SEM characterization of Ce-NiCo ₂ O ₄ /C@Ni foam in FIG3 .

The Ce-NiCo ₂ O ₄ /C@Ni foam electrode prepared in Example 1 was used as the working electrode, Ag/AgCl was used as the reference electrode, and the carbon rod was used as the counter electrode, and placed in a hydrogen peroxide electrolyte to prepare a three-electrode system, wherein the hydrogen peroxide electrolyte was prepared as follows:

NaOH and H ₂ O ₂ were dissolved in water to obtain an H ₂ O ₂ electrolyte with a NaOH concentration of 3 mol·L ^-1 and a H ₂ O ₂ concentration of 0.70 mol·L ^-1 .

The constructed three-electrode system was subjected to electroreduction reaction at a voltage of -0.6 V vs. Ag/AgCl, with a chronoamperometric test _of 480 _mA ·cm ^-2 , as shown in FIG. 4 .

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims (10)

1. A method for preparing a Ce-NiCo ₂ O ₄ /C@Ni foam electrode, characterized in that it comprises the following steps: (1) dissolving cerium nitrate, cobalt nitrate, nickel nitrate, urea and ammonium fluoride in water to obtain an electrolyte; (2) placing nickel foam in a polytetrafluoroethylene liner, transferring the electrolyte to the polytetrafluoroethylene liner in which the nickel foam is placed, and then placing the nickel foam in a reactor and hydrothermally heating the nickel foam at 100° C. to 140° C. for 4 h to 8 h. After naturally cooling to room temperature, the nickel foam is taken out after hydrothermal treatment, and the surface is rinsed with deionized water and alcohol, and then vacuum dried to obtain Ce-Co ₂ Ni(OH) _x /NF; (3) dissolving dimethylimidazole in a methanol solution to obtain a dimethylimidazole solution, placing the dried nickel foam in (2) in a polytetrafluoroethylene liner, transferring the dimethylimidazole solution to the polytetrafluoroethylene liner containing the dried nickel foam, placing the nickel foam in a reaction kettle, and hydroheating the reaction mixture at 80° C. to 120° C. for 4 h to 6 h. After naturally cooling the nickel foam to room temperature, the nickel foam is taken out after the second hydrothermal treatment, and rinsed alternately with alcohol and deionized water, and dried. (4) The nickel foam dried in step (3) is placed in a muffle furnace, and the temperature is raised to 300° C.-400° C. and kept at this temperature for 1 h-3 h to obtain Ce-NiCo ₂ O ₄ /C@Ni foam. 2. The method for preparing the Ce-NiCo ₂ O ₄ /C@Ni foam electrode according to claim 1, characterized in that the mass concentrations of cerium nitrate, cobalt nitrate, nickel nitrate, urea and ammonium fluoride in the electrolyte are 1 g/L, 19.4 g/L, 9.7 g/L, 30 g/L and 14.8 g/L, respectively. 3 . The method for preparing the Ce-NiCo ₂ O ₄ /C@Ni foam electrode according to claim 1 , wherein the size of the nickel foam is 2 cm×3 cm. 4. The method for preparing Ce- _{NiCo2O4 /} C@Ni foam electrode according to claim 1, characterized in that the mass concentration of the dimethylimidazole is 8g/L-12g/L, and the concentration of the methanol solution is 30%-70%. 5. The method for preparing Ce- _{NiCo2O4 /} C@Ni foam electrode according to claim 1, characterized in that in step (3), the drying temperature is 60-80°C and the drying time is 8-14 hours. 6 . The method for preparing Ce-NiCo ₂ O ₄ /C@Ni foam electrode according to claim 1 , wherein the heating rate is 2° C.·min ^-1 . 7 . The method for preparing the Ce-NiCo ₂ O ₄ /C@Ni foam electrode according to claim 1 , wherein the specification of the polytetrafluoroethylene liner is 50 mL. 8. The method for preparing the Ce- _{NiCo2O4 /} C@Ni foam electrode according to claim 1, characterized in that the Ce _{- NiCo2O4} /C@Ni foam catalyst is a working electrode, a carbon rod is a counter electrode, and Ag/AgCl is a reference electrode. 9. A Ce _{- NiCo2O4} /C@Ni foam electrode, characterized in that it is prepared by the method according to any one of claims 1 to 8. 10. The application of the Ce-NiCo ₂ O ₄ /C@Ni foam electrode according to claim 9, characterized in that the Ce-NiCo ₂ O ₄ /C@Ni foam electrode is applied in a hydrogen peroxide electroreduction reaction, comprising the following steps: Sodium hydroxide with a concentration of 1 mol·L ^-1 to 3 mol·L ^-1 and hydrogen peroxide with a concentration of 0.3 mol·L ^-1 to 0.70 mol·L ^-1 are mixed and dissolved in water to obtain a hydrogen peroxide electrolyte; the Ce-NiCo ₂ O ₄ /C@Ni foam electrode is used as a working electrode and placed in the hydrogen peroxide electrolyte to perform an electroreduction reaction at a voltage of -0.2 to -0.8 V vs. Ag/AgCl.