Preparation method of bismuth ferrite-based composite material

Abstract

The invention relates to a preparation method of a bismuth ferrite-based composite material. The invention aims to solve the problems of poor conductivity and few active sites of the existing bismuth ferrite electrode material, and provides a preparation method of an efficient electro-catalytic hydrogen evolution catalyst. According to the method, bismuth nitrate, ferric chloride, ethylene glycol, ammonia water, sodium hydroxide, thiourea, ammonium molybdate and cobalt nitrate are used as raw materials, a two-step hydrothermal method is adopted, the bismuth ferrite-based cobalt-doped molybdenum disulfide composite material is prepared, and the preparation method is provided for improving the electro-catalytic hydrogen evolution performance of existing bismuth ferrite.

Description

Technical Field

[0001] The invention relates to the preparation of a bismuth ferrite-based composite material. Background Art

[0002] Electrocatalytic hydrogen evolution is attractive due to its high flexibility and applicability. Currently, precious metal-based materials are considered to be the most effective electrocatalyst materials, but their high cost limits their widespread application. Therefore, the development of efficient and abundant electrocatalyst materials is a current research focus. Due to its flexible crystal structure and the presence of transition metal oxidation states, bismuth ferrite has good chemical stability and electronic structure, which is conducive to electron excitation and migration. However, the conductivity and electrochemical active sites of bismuth ferrite still need to be improved. The construction of bismuth ferrite-based cobalt-doped molybdenum disulfide composites by two-step hydrothermal synthesis technology is an effective strategy to accelerate the kinetics of catalytic reactions, which is of great research significance for solving the problem of energy shortage. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of poor conductivity and few active sites of existing bismuth ferrite electrode materials, and to provide a method for preparing a high-efficiency electrocatalytic hydrogen evolution catalyst.

[0004] The preparation method of a bismuth ferrite-based composite material of the present invention is completed by the following steps: (1) Preparation of bismuth ferrite nanosheets: bismuth nitrate and ferric chloride are dissolved in ethylene glycol and deionized water respectively, and stirred at room temperature to dissolve them, and then the bismuth nitrate solution is added dropwise to the ferric chloride solution; ammonia water is then added dropwise to the mixed solution to adjust the pH value of the solution to 10-11, and the precipitate is collected by centrifugation; then a 5M NaOH solution is added to the precipitate to form a brick red suspension, and the suspension is transferred to a 40 ml polytetrafluoroethylene reactor for hydrothermal reaction. After the reaction is completed, the suspension is cooled to room temperature, washed and dried, and then annealed in an air atmosphere to obtain bismuth ferrite nanosheets; (2) Preparation of bismuth ferrite-based cobalt-doped molybdenum disulfide composite materials: thiourea and cobalt nitrate are added to deionized water containing ammonium molybdate in sequence to obtain solution a; 49.2 mg of bismuth ferrite nanosheets are dissolved in 10 ml of deionized water and stirred thoroughly at room temperature to dissolve the solution, which is recorded as solution b; solution a is added dropwise to solution b to form a suspension c; the suspension c is then transferred to a 100 ml polytetrafluoroethylene reactor for hydrothermal reaction. After the reaction is completed, the suspension is cooled to room temperature, washed and dried to obtain a bismuth ferrite-based cobalt-doped molybdenum disulfide composite material.

[0005] In the step (1), the mass of bismuth nitrate is 1-2 g, the mass of ferric chloride is 0.5-1 g, the volume of ethylene glycol is 80-120 ml, the volume of deionized water is 80-120 ml, the stirring time is 1-2 hours, the volume of NaOH solution is 15-25 ml, the hydrothermal reaction conditions are 160-180 degrees Celsius for 24-48 hours, the drying conditions are 50-80 degrees Celsius for 10-20 hours, and the annealing conditions are 500 degrees Celsius for 2 hours.

[0006] In the step (2), the mass of thiourea is 2-2.5 g, the mass of cobalt nitrate is 0.1-0.3 g, the mass of ammonium molybdate is 1-2 g, the volume of the aqueous solution is 50-80 ml, the stirring time is 1-2 hours, the hydrothermal reaction conditions are 160-180 degrees Celsius for 24-48 hours, and the drying conditions are 50-80 degrees Celsius for 10-20 hours.

[0007] Compared with the prior art, the present invention has the following beneficial effects: the present invention prepares a highly efficient bismuth ferrite-based composite material electrocatalyst, does not require complex equipment during the preparation process, and the material has excellent electrocatalytic hydrogen evolution performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a scanning electron microscope image of the bismuth ferrite-based composite material of Example 1; Figure 2 The powder X-ray diffraction patterns of the bismuth ferrite-based composite material and the comparative sample in Example 1; Figure 3 The linear cyclic voltammetry curves of the bismuth ferrite-based composite material and the comparative sample in Example 1; Figure 4 The cyclic voltammetry curves of the bismuth ferrite-based composite material in Example 1 at different scan rates are shown. DETAILED DESCRIPTION

[0009] The technical solution of the present invention is not limited to the specific implementation modes listed below. The specific implementation modes listed below are only used to illustrate the present invention and are not limited to the technical solution described in the embodiments of the present invention. It should be understood by those skilled in the art that the present invention can still be modified or replaced by equivalents to achieve the same technical effects. As long as the use requirements are met, they are within the protection scope of the present invention.

[0010] A bismuth ferrite-based composite material of this embodiment is prepared by the following steps: (1) Preparation of bismuth ferrite nanosheets: 1.4550 g of bismuth nitrate and 0.6760 g of ferric chloride are dissolved in 100 ml of ethylene glycol and 100 ml of deionized water, respectively, and stirred for 1 hour at room temperature to dissolve, and then the bismuth nitrate solution is added dropwise to the ferric chloride solution; ammonia water is then added dropwise to the mixed solution to adjust the pH value of the solution to 10-11, and the precipitate is collected by centrifugation; then 20 ml of 5M NaOH solution is added to the precipitate to form a brick-red suspension, and then the suspension is transferred to a 40 ml polytetrafluoroethylene reactor for hydrothermal reaction at 180 degrees Celsius for 48 hours. After the reaction is completed, the mixture is cooled to room temperature, washed and dried at 60 degrees Celsius for 12 hours, and then annealed in an air atmosphere at 500 degrees Celsius for 2 hours to obtain bismuth ferrite nanosheets.

[0011] (2) Preparation of a bismuth ferrite-based cobalt-doped molybdenum disulfide composite material: 2.2000 g of thiourea and 0.100 g of cobalt nitrate were sequentially added to 50 ml of deionized water containing 1.2000 g of ammonium molybdate to obtain a solution a; 49.2 mg of bismuth ferrite nanosheets were dissolved in 10 ml of deionized water and stirred for 1 hour at room temperature to dissolve them, which was recorded as a solution b; solution a was added dropwise to solution b to form a suspension c; the suspension c was then transferred to a 100 ml polytetrafluoroethylene reactor for a hydrothermal reaction at 180 degrees Celsius for 24 hours. After the reaction was completed, the suspension was cooled to room temperature, washed and dried at 60 degrees Celsius for 12 hours to obtain a bismuth ferrite-based cobalt-doped molybdenum disulfide composite material.

[0012] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 This is a scanning electron microscope image of the bismuth ferrite-based composite material of Example 1; the composite material exhibits a nanoflower shape.

[0013] Figure 2 The powder X-ray diffraction patterns of the bismuth ferrite-based composite material and the comparison sample of Example 1 are shown; the composite material is well consistent with the bismuth ferrite and molybdenum disulfide comparison cards.

[0014] Figure 3 The linear cyclic voltammetry curves of the bismuth ferrite-based composite material of Example 1 and the comparative sample are shown; the electrocatalytic hydrogen evolution performance of the composite material is better than that of the simple bismuth ferrite material, and the performance is close to that of Pt / C.

[0015] Figure 4 The cyclic voltammetry curves at different scan rates of the bismuth ferrite-based composite material in Example 1. As the scan rate increases, the shape of the cyclic voltammetry curve does not change significantly, indicating that the material has good stability.

Claims

1. A method for preparing a bismuth ferrite-based composite material is completed by the following steps: (1) Preparation of bismuth ferrite nanosheets: bismuth nitrate and ferric chloride are dissolved in ethylene glycol and deionized water respectively, and stirred at room temperature to dissolve them, and then the bismuth nitrate solution is added dropwise to the ferric chloride solution; ammonia water is then added dropwise to the mixed solution to adjust the pH value of the solution to 10-11, and the precipitate is collected by centrifugation; then a 5M NaOH solution is added to the precipitate to form a brick red suspension, and the suspension is transferred to a 40 ml polytetrafluoroethylene reactor for hydrothermal reaction. After the reaction is completed, the suspension is cooled to room temperature, washed and dried, and then annealed in an air atmosphere to obtain bismuth ferrite nanosheets; (2) Preparation of bismuth ferrite-based cobalt-doped molybdenum disulfide composite materials: thiourea and cobalt nitrate are added to deionized water containing ammonium molybdate in sequence to obtain solution a; 49.2 mg of bismuth ferrite nanosheets are dissolved in 10 ml of deionized water and stirred thoroughly at room temperature to dissolve the solution, which is recorded as solution b; solution a is added dropwise to solution b to form a suspension c; the suspension c is then transferred to a 100 ml polytetrafluoroethylene reactor for hydrothermal reaction. After the reaction is completed, the suspension is cooled to room temperature, washed and dried to obtain a bismuth ferrite-based cobalt-doped molybdenum disulfide composite material.

2. The method for preparing a bismuth ferrite-based composite material according to claim 1, characterized in that: In the step (1), the mass of bismuth nitrate is 1-2 g, the mass of ferric chloride is 0.5-1 g, the volume of ethylene glycol is 80-120 ml, the volume of deionized water is 80-120 ml, the stirring time is 1-2 hours, the volume of NaOH solution is 15-25 ml, the hydrothermal reaction conditions are 160-180 degrees Celsius for 24-48 hours, the drying conditions are 50-80 degrees Celsius for 10-20 hours, and the annealing conditions are 500 degrees Celsius for 2 hours.

3. The method for preparing a bismuth ferrite-based composite material according to claim 1, characterized in that: In the step (2), the mass of thiourea is 2-2.5 g, the mass of cobalt nitrate is 0.1-0.3 g, the mass of ammonium molybdate is 1-2 g, the volume of the aqueous solution is 50-80 ml, the stirring time is 1-2 hours, the hydrothermal reaction conditions are 160-180 degrees Celsius for 24-48 hours, and the drying conditions are 50-80 degrees Celsius for 10-20 hours.

Images