Non-acid medium preparation method of flaky nickel phosphide array electrode material
阅读说明：本技术 一种片状磷化镍阵列电极材料的非酸介质制备方法 (Non-acid medium preparation method of flaky nickel phosphide array electrode material ) 是由 冯苗 朱阿元 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种片状磷化镍阵列电极材料的非酸介质制备方法。该方法采用非酸介质水热法和化学气相沉积法在泡沫镍基底上生长片状磷化镍阵列。具体分为三步：首先以双氧水、十六烷基三甲基溴化铵、乙醇和去离子水混合作为溶剂,通过水热法在泡沫镍表面进行氧化活化与晶面预取向；然后将活化过的泡沫镍与双氧水、去离子水和十六烷基三甲基溴化铵溶液进行水热反应,得到晶面结构有序的片状氢氧化镍阵列；最后通过化学气相沉积法与次磷酸钠反应,获得活性晶面占比大的片状磷化镍阵列电极材料。本发明采用双氧水氧化工艺替代氢氟酸刻蚀工艺,具有高效率、低成本、低毒性、环境友好、操作简单等特点,在电催化产氢领域中具有广阔的应用前景。(The invention discloses a method for preparing a non-acid medium of a flaky nickel phosphide array electrode material. The method adopts a non-acid medium hydrothermal method and a chemical vapor deposition method to grow a flaky nickel phosphide array on a foamed nickel substrate. The method comprises the following steps: firstly, mixing hydrogen peroxide, cetyl trimethyl ammonium bromide, ethanol and deionized water as a solvent, and performing oxidation activation and crystal face pre-orientation on the surface of the foamed nickel by a hydrothermal method; then carrying out hydrothermal reaction on the activated foamed nickel, hydrogen peroxide, deionized water and a cetyl trimethyl ammonium bromide solution to obtain a flaky nickel hydroxide array with an ordered crystal face structure; and finally reacting with sodium hypophosphite by a chemical vapor deposition method to obtain the flaky nickel phosphide array electrode material with a large active crystal face proportion. The invention adopts the hydrogen peroxide oxidation process to replace a hydrofluoric acid etching process, has the characteristics of high efficiency, low cost, low toxicity, environmental friendliness, simple operation and the like, and has wide application prospect in the field of electrocatalytic hydrogen production.)
1. A preparation method of a flaky nickel phosphide array electrode material is characterized by comprising the following steps: and (3) growing a flaky nickel phosphide array on the foamed nickel substrate by adopting a non-acid medium hydrothermal method and a chemical vapor deposition method.
2. The method of claim 1, wherein: the method comprises the following steps:
(1) pretreatment of foamed nickel: ultrasonically cleaning the mixture for 10 to 20min by using acetone, 3mol/L hydrochloric acid, ethanol and deionized water in sequence, and drying the mixture at 60 ℃ for later use;
(2) oxidation activation and crystal face pre-orientation of foam nickel: adding cetyl trimethyl ammonium bromide and hydrogen peroxide into a mixed solution of deionized water and ethanol, carrying out ultrasonic treatment for 10-20 min, adding foamed nickel, carrying out ultrasonic treatment for 10-20 min, carrying out hydrothermal reaction at 180 ℃ for 16-24 h, naturally cooling to room temperature, taking out activated foamed nickel, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ for later use;
(3) the structure of the flaky nickel hydroxide array grows orderly: mixing hydrogen peroxide and deionized water, carrying out ultrasonic treatment for 10-20 min, adding a 1mmol/L hexadecyl trimethyl ammonium bromide solution, and carrying out ultrasonic treatment for 10-20 min; adding the foamed nickel obtained in the step (2), performing ultrasonic treatment for 10-20 min, performing hydrothermal reaction at 180 ℃ for 16-24 h, naturally cooling to room temperature, taking out a foamed nickel sample, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ to obtain a sheet nickel hydroxide array/foamed nickel material;
(4) preparation of flaky nickel phosphide array: respectively placing sodium hypophosphite and a sheet nickel hydroxide array/foamed nickel material at two ends of a porcelain boat, placing the porcelain boat into a tube furnace, enabling the sodium hypophosphite to be positioned at an air inlet, introducing nitrogen, and carrying out heat treatment at 400 ℃ for 1h to obtain the sheet nickel phosphide array/foamed nickel electrode material.
3. The method of claim 2, wherein: in the step (2), the amount of hydrogen peroxide is 5-10 mL, the amount of deionized water is 0-5 mL, the amount of ethanol is 5-10 mL, and the amount of hexadecyl trimethyl ammonium bromide is 164-328 mg.
4. The method of claim 2, wherein: in the step (3), the amount of hydrogen peroxide is 5-10 mL, the amount of deionized water is 17-24 mL, and the amount of the cetyl trimethyl ammonium bromide solution is 1-3 mL.
5. The method according to claim 3 or 4, characterized in that: the mass fraction of the hydrogen peroxide is 30%.
6. The method of claim 2, wherein: in the step (4), the amount of the sodium hypophosphite is 80-120 mg, and the temperature rise rate of the tube furnace is 2 ℃/min.
7. A sheet-like nickel phosphide array electrode material prepared by the method of claim 1.
8. The sheet nickel phosphide array electrode material prepared by the method of claim 1 is applied to electrocatalytic hydrogen production reaction.
Technical Field
The invention belongs to the technical field of electrocatalysis hydrogen production, and particularly relates to a preparation method of a sheet nickel phosphide array/foam nickel electrode material.
Background
As fossil fuels contribute to global warming and pollution, there is an urgent need to find clean, renewable alternative energy sources. The water electrolysis technique is a reliable technique for storing and transmitting wind energy and solar energy, theoretically zero pollution can be realized by generating hydrogen and oxygen, however, the water decomposition reaction requires high overpotential to obtain proper reaction rate. Although platinum-based materials and ruthenium-based oxides are the most effective electrocatalysts for hydrogen and oxygen evolution reactions, the scarcity, high cost and instability of noble metals have limited their widespread use. At present, a plurality of high-activity non-noble metal catalysts with abundant earth reserves are designed for hydrogen evolution and oxygen evolution reactions, such as chalcogenides, phosphides, carbides and the like.
The nickel phosphide has an electronic structure similar to that of hydrogenase, and is a high-efficiency hydrogen evolution catalyst. The phosphorus atoms of the nickel phosphide enter the crystal lattice of the nickel to form a gap compound, so that the nickel phosphide has good conductivity and corrosion resistance and conforms to the characteristics of a high-efficiency electro-catalytic electrode. In recent years, various methods for preparing nickel phosphide have been reported, wherein the hydrothermal synthesis method has significant advantages and good morphology controllability, and a flaky nickel phosphide array can be vertically grown in situ on the surface of foamed nickel through phosphorization, so that the nickel phosphide has excellent electrochemical characteristics. However, there are still the following problems to be solved: (1) the surface pickling and activating process of the foamed nickel relates to a highly toxic chemical reagent (such as hydrofluoric acid), which harms the personal safety and causes serious environmental pollution; (2) the preparation process is complex and has strict requirements on reaction temperature, atmosphere and production equipment. Therefore, the development of a preparation method with high efficiency, low cost, low toxicity, environmental friendliness and simple operation to obtain the nickel phosphide electrode material with the characteristics of uniform structure, regular arrangement, good controllability and the like is an important key for realizing modern production.
In the "preparation method of integrated nickel-based porous nickel phosphide hydrogen evolution electrode" of publication No. CN106498434A, deionized water and organic alcohol are mixed according to a ratio of 1: 0-100 mixing; weak acid (hydrofluoric acid and the like) with the concentration of 0.01-2 mol/L is added; adding a foamed nickel substrate, carrying out etching reaction for 1-10 h at 10-100 ℃ to form a nickel-based porous precursor, washing with deionized water, and drying; and putting the nickel-based porous precursor and sodium hypophosphite into a mixed atmosphere of hydrogen and inert gas at the temperature of 250-400 ℃ for phosphating treatment to obtain the integrated nickel-based porous nickel phosphide electrode material. The scanning electron micrograph thereof is shown in FIG. 9. The method utilizes hydrogen ions of hydrofluoric acid to etch the foam nickel under the hydrothermal critical condition, the obtained nickel phosphide electrode material has lower structural order degree and is liable to influence the electrochemical performance and the cycle stability of the material, and meanwhile, the hydrofluoric acid is used as an etching agent, thereby not only harming the personal safety, but also generating polluting waste materials and deviating from the green chemical synthesis concept.
In the method for preparing the nickel hydroxide nanosheet array material growing on the surface of the foamed nickel, disclosed in publication No. CN110040792B, the foamed nickel is firstly placed in ethanol for ultrasonic cleaning, the foamed nickel is taken out and then washed with deionized water, the washed foamed nickel is then placed in an acid solution (such as hydrofluoric acid) for soaking for 1-2 hours, the washed foamed nickel is then taken out and then placed in the deionized water for ultrasonic cleaning, and finally the foamed nickel is immersed in the deionized water for natural oxidation for 2-5 days, so that the nickel hydroxide nanosheet array material growing on the surface of the foamed nickel is obtained. The method utilizes hydrofluoric acid to carry out acid pickling activation on the surface of the foamed nickel, has great harm to the environment, needs to spend a great deal of cost to treat highly toxic industrial waste in the later period, increases the production cost, and does not conform to the green chemical synthesis concept.
In the sodium ion battery nanosheet array nickel phosphide/3D graphene composite material and the preparation method thereof of publication No. CN107331851A, firstly, 3D graphene is deposited on foamed nickel by a chemical vapor deposition method in which three gases of nitrogen, hydrogen and methane participate in a reaction; then carrying out hydrothermal reaction with deionized water with pH =3, and growing a nickel hydroxide nano array on the foamed nickel substrate deposited with the 3D graphene; and finally, carrying out heat treatment on the 3D graphene loaded with the nickel hydroxide nano array and sodium hypophosphite in an inert atmosphere to prepare the nanosheet array nickel phosphide/3D graphene composite material. The method needs to introduce a special gas medium at high temperature, has higher requirements on equipment and has complex preparation conditions. In addition, the method requires the use of any acid to adjust the pH of the deionized water, and is not disclosed.
Disclosure of Invention
The invention aims to provide a method for preparing a non-acid medium of a sheet nickel phosphide array electrode material, which aims to solve the problem of toxicity in the surface acid treatment and activation process of foam nickel in the prior art. The preparation method has the characteristics of high efficiency, low cost, low toxicity, environmental friendliness, simplicity in operation and the like, the hydrogen peroxide oxidation process is adopted to replace a hydrofluoric acid etching process, no virulent hydrofluoric acid and an additional nickel source are required to be added, no binder is required to be used for adhesion, and the prepared sheet nickel phosphide array electrode material has a wide application prospect in the field of electrocatalytic hydrogen production.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a sheet nickel phosphide array electrode material comprises the following steps:
(1) ultrasonically cleaning the mixture for 10 to 20min by using acetone, hydrochloric acid (3 mol/L), ethanol and deionized water in sequence, and drying the mixture for later use at 60 ℃;
(2) oxidation activation and crystal face pre-orientation of foam nickel: weighing hexadecyl trimethyl ammonium bromide, pouring the hexadecyl trimethyl ammonium bromide into a beaker, adding hydrogen peroxide, deionized water and ethanol into the beaker, and carrying out ultrasonic treatment for 10-20 min to form a uniform solution. Adding foamed nickel with the size of 1 multiplied by 3cm into the solution, carrying out ultrasonic treatment for 10-20 min, transferring the solution and the foamed nickel into a polytetrafluoroethylene reaction kettle, and carrying out hydrothermal reaction for 16-24 h at 180 ℃. Naturally cooling to room temperature, taking out the activated foam nickel, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ for later use;
(3) the structure of the flaky nickel hydroxide array grows orderly: pouring hydrogen peroxide and deionized water into a beaker, carrying out ultrasonic treatment for 10-20 min, adding a 1mmol/L hexadecyl trimethyl ammonium bromide solution, and carrying out ultrasonic treatment for 10-20 min. And (3) adding the foamed nickel activated in the step (2) into the solution, and carrying out ultrasonic treatment for 10-20 min. And (3) transferring the foamed nickel and the solution into a polytetrafluoroethylene reaction kettle according to the mode of the step (2), and carrying out hydrothermal reaction for 16-24 h at 180 ℃. After the reaction is finished, naturally cooling to room temperature, taking out the foam nickel sample, and washing with deionized water and ethanol for three times respectively. Drying at 60 ℃ to obtain a sheet nickel hydroxide array/foamed nickel material;
(4) preparation of flaky nickel phosphide array: firstly, 80-120 mg of sodium hypophosphite is weighed and placed at one end of a porcelain boat, and a sheet nickel hydroxide array/foamed nickel material with the size of 1 multiplied by 2cm is placed at the other end of the porcelain boat. Then, the porcelain boat is placed into a tube furnace, sodium hypophosphite is positioned at an upper air inlet, nitrogen is introduced, and heat treatment is carried out for 1h at 400 ℃ to obtain the sheet nickel phosphide array/foamed nickel electrode material.
Preferably, the amount of hydrogen peroxide (30% by mass) in the step (2) is 5-10 mL, the amount of deionized water is 0-5 mL, the amount of ethanol is 5-10 mL, and the amount of cetyl trimethyl ammonium bromide is 164-328 mg.
Preferably, the amount of hydrogen peroxide (30% by mass) in the step (3) is 5-10 mL, the amount of deionized water is 17-24 mL, and the amount of the cetyl trimethyl ammonium bromide solution is 1-3 mL.
Preferably, the temperature rise rate of the tube furnace in the step (4) is 2 ℃/min.
The flaky nickel phosphide array/foamed nickel electrode material is prepared by the method.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method realizes the replacement of highly toxic hydrofluoric acid etching activation by hydrogen peroxide oxidation activation on the surface of the nickel metal: according to the method, under the hydrothermal critical condition, the reasonable crystal face regulation and control are carried out on the process of oxidizing the foamed nickel by hydrogen peroxide by virtue of the cetyl trimethyl ammonium bromide serving as the surfactant, so that the efficient and controllable in-situ array growth of the nickel hydroxide nanosheets rich in the (001) crystal face on the surface of the foamed nickel is realized, and the stable formation of the (001) active crystal face of the nickel phosphide is facilitated when the nickel hydroxide is converted into the nickel phosphide. The reaction equation for replacing highly toxic hydrofluoric acid by hydrogen peroxide oxidation activation on the surface of the nickel metal is as follows:
Ni (s) + H2O2 (aq) → Ni(OH)2 (s)
different from industrial waste generated by highly toxic hydrofluoric acid, the product obtained after the hydrogen peroxide is reacted in the invention is water, and the invention has no industrial waste and no pollution to the environment.
(2) Realizing the controllable in-situ array growth of the two-dimensional sheet structure of the nickel phosphide electrode material: the nickel phosphide nanosheet growing on the surface of the foamed nickel in an in-situ array manner has a large number of (001) active crystal faces and effective active sites, and has good catalytic performance of water electrolysis hydrogen evolution reaction.
(3) The utilization rate of nickel atoms is high: according to the invention, hydrogen peroxide oxidation activation is utilized to carry out surface pre-orientation treatment on the foamed nickel, and the foamed nickel subjected to surface pre-orientation treatment is taken as a nickel source, so that the quality and yield of the nickel hydroxide nanosheet rich in the (001) crystal face are improved, no extra high-purity nickel salt is required to be added, unnecessary reagent waste is avoided, and the atom utilization rate of nickel is improved.
(4) The preparation process is simple, and the requirement on equipment is low: the synthesis process does not need high-temperature treatment or special gas introduction, and the synthesis equipment is simple.
(5) High benefit, low cost, green environmental protection: in the whole product manufacturing process, only a small amount of low-toxicity industrial waste is generated, and a large amount of cost is not needed to be spent on treating the industrial waste, so that the concept of green, low-carbon, environmental protection and sustainable development is embodied.
Drawings
FIG. 1 is a scanning electron microscope data chart of a sheet-like nickel hydroxide array material prepared in example 1 of the present invention;
FIG. 2 is a scanning electron microscope data chart of the flaky nickel phosphide array electrode material prepared in example 1 of the invention;
FIG. 3 is a scanning electron microscope data chart of the sheet-like nickel hydroxide array electrode material prepared in comparative example 1 of the present invention;
FIG. 4 is a scanning electron microscope data chart of the flaky nickel phosphide array electrode material prepared in comparative example 1 of the invention;
fig. 5 is an elemental distribution diagram of nickel phosphide nanosheets prepared in example 1 of the present invention;
FIG. 6 is a graph of X-ray diffraction data of a flaky nickel phosphide array electrode material prepared in example 1 of the invention;
FIG. 7 is a hydrogen evolution polarization curve of the sheet-like nickel phosphide array electrode materials prepared in example 1 of the present invention and comparative example 1 in an acidic solution;
FIG. 8 shows the current density of 10mA cm for the sheet-like nickel phosphide array electrode material prepared in example 1 of the invention-2A lower timing voltage curve;
FIG. 9 is a scanning electron microscope data image of nickel-based nickel phosphide disclosed in publication No. CN 106498434A.
Detailed Description
In order to make the content of the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the embodiments are intended to illustrate the present invention and should not be construed as limiting the present invention.
Example 1
(1) Ultrasonically cleaning the mixture for 10min by using acetone, hydrochloric acid (3 mol/L), ethanol and deionized water in sequence, and drying the mixture at 60 ℃ for later use;
(2) 328mg of hexadecyl trimethyl ammonium bromide is weighed and added into a beaker, 5mL of hydrogen peroxide, 5mL of deionized water and 10mL of ethanol are added into the beaker, and ultrasonic treatment is carried out for 10min to obtain a clear and transparent solution. Nickel foam with a size of 1X 3cm was added to the above solution and sonicated for 10 min. Then the foamed nickel and the solution are transferred into a polytetrafluoroethylene hydrothermal kettle together, and the hydrothermal reaction is carried out for 20 hours at 180 ℃. Naturally cooling to room temperature, taking out the activated foam nickel, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ for later use;
(3) 5mL of hydrogen peroxide and 23mL of deionized water are weighed and poured into a beaker, and are subjected to ultrasonic treatment for 10min, then 2mL of 1mmol/L hexadecyl trimethyl ammonium bromide solution is added, and the ultrasonic treatment is carried out for 10 min. And (3) adding the foamed nickel activated in the step (2) into the solution, and carrying out ultrasonic treatment for 10 min. And (3) transferring the foamed nickel and the solution into a polytetrafluoroethylene reaction kettle in the mode of the step (2), and carrying out hydrothermal reaction for 20 hours at 180 ℃. Naturally cooling to room temperature, taking out the foam nickel sample, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ to obtain a sheet nickel hydroxide array material;
(4) 100mg of sodium hypophosphite was weighed into one end of the boat and a 1X 2 cm-sized nickel hydroxide sheet array was placed into the other end of the boat. Then, the porcelain boat is placed into a tube furnace, the sodium hypophosphite is positioned at an upper air inlet, nitrogen is introduced, and heat treatment is carried out for 1h at 400 ℃ to obtain the sheet nickel phosphide array electrode material.
Example 2
(1) Ultrasonically cleaning the mixture for 10min by using acetone, hydrochloric acid (3 mol/L), ethanol and deionized water in sequence, and drying the mixture at 60 ℃ for later use;
(2) 164mg of hexadecyl trimethyl ammonium bromide is weighed and added into a beaker, 10mL of hydrogen peroxide and 10mL of ethanol are added into the beaker, and ultrasonic treatment is carried out for 10min to obtain a clear and transparent solution. Nickel foam with a size of 1X 3cm was added to the above solution and sonicated for 10 min. Then the foamed nickel and the solution are transferred into a polytetrafluoroethylene hydrothermal kettle together, and the hydrothermal reaction is carried out for 24 hours at 180 ℃. Naturally cooling to room temperature, taking out the activated foam nickel, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ for later use;
(3) 5mL of hydrogen peroxide and 22mL of deionized water are weighed and poured into a beaker, and are subjected to ultrasonic treatment for 10min, then 3mL of 1mmol/L hexadecyl trimethyl ammonium bromide solution is added, and the ultrasonic treatment is carried out for 10 min. And (3) adding the foamed nickel activated in the step (2) into the solution, and carrying out ultrasonic treatment for 10 min. And (3) transferring the foamed nickel and the solution into a polytetrafluoroethylene reaction kettle in the mode of the step (2), and carrying out hydrothermal reaction for 20 hours at 180 ℃. Naturally cooling to room temperature, taking out the foam nickel sample, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ to obtain a sheet nickel hydroxide array material;
(4) 100mg of sodium hypophosphite was weighed into one end of the boat and a 1X 2 cm-sized nickel hydroxide sheet array was placed into the other end of the boat. Then, the porcelain boat is placed into a tube furnace, the sodium hypophosphite is positioned at an upper air inlet, nitrogen is introduced, and heat treatment is carried out for 1h at 400 ℃ to obtain the sheet nickel phosphide array electrode material.
Example 3
(1) Ultrasonically cleaning the mixture for 10min by using acetone, hydrochloric acid (3 mol/L), ethanol and deionized water in sequence, and drying the mixture at 60 ℃ for later use;
(2) 328mg of hexadecyl trimethyl ammonium bromide is weighed and added into a beaker, 5mL of hydrogen peroxide, 5mL of deionized water and 10mL of ethanol are added into the beaker, and ultrasonic treatment is carried out for 10min to obtain a clear and transparent solution. Nickel foam with a size of 1X 3cm was added to the above solution and sonicated for 10 min. Then the foamed nickel and the solution are transferred into a polytetrafluoroethylene hydrothermal kettle together, and the hydrothermal reaction is carried out for 24 hours at 180 ℃. Naturally cooling to room temperature, taking out the activated foam nickel, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ for later use;
(3) 5mL of hydrogen peroxide and 24mL of deionized water are weighed and poured into a beaker, and subjected to ultrasonic treatment for 10min, and then 1mL of 1mmol/L hexadecyl trimethyl ammonium bromide solution is added, and the ultrasonic treatment is carried out for 10 min. And (3) adding the foamed nickel activated in the step (2) into the solution, and carrying out ultrasonic treatment for 10 min. And (3) transferring the foamed nickel and the solution into a polytetrafluoroethylene reaction kettle in the mode of the step (2), and carrying out hydrothermal reaction for 24 hours at 180 ℃. Naturally cooling to room temperature, taking out the foam nickel sample, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ to obtain a sheet nickel hydroxide array material;
(4) 100mg of sodium hypophosphite was weighed into one end of the boat and a 1X 2 cm-sized nickel hydroxide sheet array was placed into the other end of the boat. Then, the porcelain boat is placed into a tube furnace, the sodium hypophosphite is positioned at an upper air inlet, nitrogen is introduced, and heat treatment is carried out for 1h at 400 ℃ to obtain the sheet nickel phosphide array electrode material.
Comparative example 1
(1) Pretreatment of foamed nickel: ultrasonically cleaning the mixture for 10min by using acetone, hydrochloric acid (3 mol/L), ethanol and deionized water in sequence, and drying the mixture at 60 ℃ for later use;
(2) 5mL of hydrogen peroxide and 23mL of deionized water are weighed and poured into a beaker, and are subjected to ultrasonic treatment for 10min, then 2mL of 1mmol/L hexadecyl trimethyl ammonium bromide solution is added, and the ultrasonic treatment is carried out for 10 min. Adding activated foam nickel, and performing ultrasonic treatment for 10 min. And transferring the foamed nickel and the solution into a polytetrafluoroethylene reaction kettle, and carrying out hydrothermal reaction for 20 hours at 180 ℃. Naturally cooling to room temperature, taking out the foam nickel sample, washing with deionized water and ethanol for three times respectively, and drying at 60 ℃ to obtain a sheet nickel hydroxide array material;
(3) 100mg of sodium hypophosphite is weighed and placed at one end of the porcelain boat, and a sheet nickel hydroxide array/nickel foam with the size of 1X 2cm is placed at the other end of the porcelain boat. Then, the porcelain boat is placed into a tube furnace, the sodium hypophosphite is positioned at an upper air inlet, nitrogen is introduced, and heat treatment is carried out for 1h at 400 ℃ to obtain the sheet nickel phosphide array electrode material.
Fig. 1 and 2 are scanning electron micrographs of the flaky nickel hydroxide array and the flaky nickel phosphide array prepared in example 1, and fig. 3 and 4 are scanning electron micrographs of the nickel hydroxide and nickel phosphide prepared in comparative example 1, from which it can be seen that the nickel hydroxide nanosheets prepared in example 1 are thinner and larger in size, indicating a greater proportion of the nickel hydroxide (001) crystal plane. After phosphorization, the nickel phosphide nanosheet of example 1 has a porous structure and has more active sites.
Fig. 5 is an element distribution diagram of the nickel phosphide nanosheets prepared in example 1, from which it is clear that Ni and P are uniformly distributed on the nickel phosphide nanosheets.
FIG. 6 is an X-ray diffraction pattern of a nickel phosphide electrode material prepared in example 1, from which it can be seen that the three-strong peaks at angles of 44.5, 51.8 and 76.3 belong to the diffraction peaks of nickel, and the remaining peaks belong to the diffraction peaks of nickel phosphide. The nickel hydroxide nanosheet array is completely converted into nickel phosphide after the phosphorization.
To verify the electrochemical performance of the flake nickel phosphide array/nickel foam prepared in example 1, the hydrogen evolution performance was evaluated using a three-electrode system. An electrode to be measured is taken as a working electrode, a platinum sheet and Ag/AgCl are taken as a counter electrode and a reference electrode respectively, and a 0.5mol/L sulfuric acid solution (pH = 0.13) is taken as an electrolyte. The electrochemical tester adopts CHI 660D electrochemical station (Shanghai Chenghua apparatus Co., Ltd.), and the potential testing range for testing the linear scanning curve (LSV) is-0.2 to-0.8V (vsAg/AgCl), sweep rate was 5 mV/s. The scanning frequency of the electrochemical impedance spectroscopy is 1050.01 Hz. FIG. 7 is a hydrogen evolution polarization curve of the nickel phosphide electrodes prepared in example 1 and comparative example 1. It can be seen that when the current density reached 10mA cm-2Meanwhile, the hydrogen evolution potential of the nickel phosphide electrode material of comparative example 1 is 135mV, and the hydrogen evolution potential of the nickel phosphide electrode material prepared in example 1 is only 75mV, which indicates that the electrochemical performance of the latter is stronger. In addition, the stability test results of the nickel phosphide electrode material prepared in example 1 showed that the thickness of the nickel phosphide electrode material was 10 mA-cm-2After the electrode is continuously operated for 24 hours under the current density, the voltage is not obviously changed, and the electrode has good stability.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.