A nickel hydroxide / amorphous black phosphorus electrode electrocatalytic water splitting device

Abstract

This invention discloses a nickel hydroxide / amorphous black phosphorus electrode electrocatalytic water splitting device, belonging to the field of electrochemical technology. By constructing an electron transport engineering interface for black phosphorus-based transition metal oxides, this invention designs a highly efficient OER catalytic system composed of amorphous black phosphorus and β-nickel hydroxide, which has advantages such as simple preparation method and precise interface control. Compared with a single β-nickel hydroxide catalyst, the introduction of black phosphorus significantly enhances the electron transport capability and structural stability of the composite material, thereby improving catalytic activity and stability. Compared with crystalline black phosphorus, amorphous black phosphorus, due to its higher carrier mobility, further enhances interfacial charge transfer, promotes the dynamic maintenance of active sites, and ensures the continuous high efficiency of the reaction process. The electrocatalytic water splitting device constructed by this invention can efficiently promote the decomposition of water molecules under light conditions, providing feasibility for constructing a solar-driven water splitting system.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a nickel hydroxide / amorphous black phosphorus electrode electrocatalytic water splitting device. Background Technology

[0002] As the global energy structure transitions towards cleaner and lower-carbon energy, hydrogen energy, with its high energy density and zero carbon emissions, has become an important energy source. Electrocatalytic water splitting, as a core pathway for green hydrogen production, enables the efficient conversion of electrical energy into hydrogen. However, the overall efficiency of this technology is limited by the high overpotential and slow reaction kinetics of the oxygen evolution reaction (OER). Although noble metal-based catalysts exhibit excellent OER catalytic activity, their scarcity and high cost severely restrict their large-scale application. Therefore, developing efficient, stable, and economical non-noble metal-based OER electrocatalysts has significant scientific research value and commercial potential.

[0003] Among numerous non-noble metal catalysts, transition metal-based materials have been extensively studied due to their high catalytic activity. Under anodic potential, these materials undergo surface reconstruction, forming high-valence metal oxides that serve as active centers for oxidation-reduction reactions (OERs). However, excessive oxidation of the metal can affect the catalyst's reaction stability. Studies have shown that the electron-proton transfer rate on the catalyst surface has a significant impact on the metal oxidation process and its stability. When the electron-proton transfer process is rapid, the electrons lost during metal oxidation can be promptly compensated by electrons released from oxygen atoms during water oxidation, effectively suppressing the risk of excessive metal oxidation. In this case, metal oxidation and water oxidation are closely linked and occur almost synchronously. Conversely, if the electron-proton transfer kinetics at the catalyst's active sites are sluggish, the metal will continuously lose electrons and oxidize, requiring a higher voltage to restore electron balance, resulting in a significant plateau between the metal oxidation peak and the water oxidation reaction. Therefore, it is necessary to optimize the charge transfer behavior at the catalyst interface to enhance the electron-proton transfer kinetics, thereby narrowing the potential range between the metal oxidation peak and water electrolysis, and ultimately improving the overall stability of the catalytic system. Summary of the Invention

[0004] The purpose of this invention is to provide a nickel hydroxide / amorphous black phosphorus electrode electrocatalytic water splitting device to solve the aforementioned problems in the background art. This invention designs a nickel hydroxide / amorphous black phosphorus electrode material with high catalytic performance, prepared by loading an oxygen evolution reaction (OER) electrocatalyst of nickel hydroxide / amorphous black phosphorus onto a carbon paper substrate. By effectively controlling the electrode's microstructure and interfacial electron transport engineering, the interfacial charge transfer rate is accelerated, effectively suppressing the excessive oxidation and dissolution of metallic Ni. Compared to the unmodified electrocatalyst, the catalytic activity and stability of the electrode material are significantly improved. The electrocatalytic water splitting device constructed by this invention can efficiently promote the decomposition of water molecules under light conditions, providing feasibility for constructing a solar-driven water splitting system.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of this invention is to provide a method for preparing a nickel hydroxide / amorphous black phosphorus electrode, comprising the following steps:

[0007] 0.5 g of red phosphorus powder was added to 75 mL of ethylenediamine and intercalated to obtain crystalline black phosphorus intercalated with ethylenediamine.

[0008] The crystalline black phosphorus intercalated with ethylenediamine was mixed with water and heated to obtain amorphous black phosphorus.

[0009] The amorphous black phosphorus was mixed with β-nickel hydroxide powder in a dispersant to obtain a dispersion, which was then dried to obtain a nickel hydroxide / amorphous black phosphorus mixed powder.

[0010] The nickel hydroxide / amorphous black phosphorus mixed powder is loaded onto an electrode substrate to obtain the nickel hydroxide / amorphous black phosphorus electrode.

[0011] Preferably, the ratio of red phosphorus powder to ethylenediamine is 0.5 g:75 mL; the intercalation reaction temperature is 165 °C and the time is 24 h.

[0012] Preferably, the ratio of crystalline black phosphorus intercalated with ethylenediamine to water is 0.4 g:70 mL; the heating reaction temperature is 160 °C and the time is 24 h.

[0013] Preferably, the ratio of amorphous black phosphorus, β-nickel hydroxide, and dispersant is 5 mg:80 mg:10 mL; the dispersant is ethanol; and the drying treatment is vacuum drying at 50 °C for 12 h.

[0014] Preferably, the electrode substrate is carbon paper, and the loading amount of the nickel hydroxide / amorphous black phosphorus mixed powder on the electrode substrate is 1 mg cm⁻¹. -2 .

[0015] Preferably, the preparation method of the β-nickel hydroxide powder includes the following steps: dissolving 2 mmol of nickel nitrate in 40 mL of water, then adding 4 mL of oleylamine and 20 mL of ethanol, heating at 190 °C for 16 h, and pulverizing to obtain the β-nickel hydroxide powder.

[0016] The second technical solution of the present invention provides a nickel hydroxide / amorphous black phosphorus electrode prepared according to the above preparation method.

[0017] The third technical solution of the present invention provides an application of the above-mentioned nickel hydroxide / amorphous black phosphorus electrode in the field of electrocatalytic water splitting.

[0018] The fourth technical solution of the present invention provides an apparatus for electrocatalytic water splitting, using the above-mentioned nickel hydroxide / amorphous black phosphorus electrode as the electrode material of the apparatus.

[0019] Preferably, the device is equipped with a solar panel, which converts light energy into electrical energy to power the device's circuitry.

[0020] The beneficial technical effects of the present invention are as follows:

[0021] This invention designs a highly efficient OER catalytic system composed of amorphous black phosphorus and β-nickel hydroxide by constructing an interfacial electron transport engineering method based on black phosphorus-based transition metal oxides. This system offers advantages such as simple preparation and precise interfacial control. Compared to a single β-nickel hydroxide catalyst, the introduction of black phosphorus significantly enhances the electron transport capability and structural stability of the composite material, thereby improving catalytic activity and stability. Compared to crystalline black phosphorus, amorphous black phosphorus, due to its higher carrier mobility, further enhances interfacial charge transfer, promotes the dynamic maintenance of active sites, and ensures the sustained high efficiency of the reaction process.

[0022] Electrochemical test results show that the nickel hydroxide / amorphous black phosphorus electrode of the present invention exhibits performance at 10 mA·cm⁻¹. -2 The overpotential at the current density was only 332 mV, exhibiting excellent electrochemical stability (120 h) and high resistance to metal dissolution. The loading of amorphous black phosphorus shortened the distance between the metal oxidation peak and the OER onset potential, significantly accelerating the interfacial charge transfer rate and effectively suppressing Ni oxidation. 3+ Excessive oxidation and dissolution of the catalyst improved its activity and stability, ultimately increasing the efficiency of the entire electrocatalytic water splitting device. The nickel hydroxide / amorphous black phosphorus electrode achieved a solar-to-hydrogen conversion efficiency of 6.49% (η0.05). STHThe efficiency of the catalytic converter is 89.8% higher than that of β-nickel hydroxide (3.42%), and it also has a Faraday efficiency of nearly 100%. Therefore, the constructed black phosphorus-based composite catalytic system has high activity, high stability and excellent solar-to-hydrogen energy conversion characteristics, which will help promote the application and development of efficient OER catalytic systems in the field of practical energy conversion. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The X-ray diffraction (XRD) spectra of β-nickel hydroxide, ethylenediamine-intercalated crystalline black phosphorus, amorphous black phosphorus, nickel hydroxide / amorphous black phosphorus mixed powder in Example 1, and nickel hydroxide / ethylenediamine-intercalated crystalline black phosphorus mixed powder in Comparative Example 1 are shown.

[0025] Figure 2 These are transmission electron microscopy (TEM) images of (a) β-nickel hydroxide, (c) nickel hydroxide / amorphous black phosphorus mixed powder in Example 1, and (b) nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus mixed powder in Comparative Example 1.

[0026] Figure 3 These are the Raman spectra of β-nickel hydroxide, nickel hydroxide / amorphous black phosphorus mixed powder in Example 1, and nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus mixed powder in Comparative Example 1.

[0027] Figure 4 The OER performance of the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 in 1 M KOH electrolyte is shown; wherein, (a) linear sweep voltammetry (LSV) test curve, (b) current density at 10 mA cm⁻¹ -2 (c) overpotential, (d) Tafel slope, and (e) current density of 10 mA cm⁻¹ -2 Electrochemical stability at that time;

[0028] Figure 5The Ni concentration was determined by inductively coupled plasma mass spectrometry (ICP-MS) after the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 were reacted in 1 M KOH electrolyte for 2 h.

[0029] Figure 6 The LSV curves of the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2, as well as the potential difference from their oxidation peaks to the OER initiation potential.

[0030] Figure 7 The Nyquist plots and corresponding phase angle changes of the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2, obtained by electrochemical impedance spectroscopy (EIS) under bias voltages of 1.2 V-1.7 V; where (a), (b), and (c) are the Nyquist plots of the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode, the β-nickel hydroxide electrode, and the nickel hydroxide / amorphous black phosphorus electrode, respectively, and (d) shows the phase angle change.

[0031] Figure 8 This is a schematic diagram of the structure of the photo-assisted electrocatalytic water splitting device of the present invention;

[0032] Figure 9 The current-voltage (JV) characteristic curves of the photo-assisted electrocatalytic water splitting devices prepared using the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 are shown.

[0033] Figure 10 The graph shows the H2 and O2 production curves of the photo-assisted electrocatalytic water splitting device prepared using the nickel hydroxide / amorphous black phosphorus electrode in Example 1 under a 0 V bias voltage. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0035] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. It should be noted that any aspects of this invention not described in detail are conventional practices in the art and are not the focus of this invention.

[0037] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0038] This invention discloses a method for preparing a nickel hydroxide / amorphous black phosphorus electrode, comprising the following steps:

[0039] (1) Preparation of β-Ni(OH)2 sample: First, 0.582 g (2.0 mmol) of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) was dissolved in 40 mL of deionized water and a clear green solution was formed under magnetic stirring. 4 mL of oleylamine was quickly injected into the green solution, and then 20 mL of ethanol was added. The mixture was stirred for 30 min and then transferred to a 100 mL polytetrafluoroethylene liner. The mixture was placed in a corresponding stainless steel autoclave and heated to 190 °C for 16 h. After the reaction was completed, the mixture was naturally cooled to room temperature and the green sample was collected. The sample was washed with cyclohexane, distilled water and ethanol respectively and then dried under vacuum at 50 °C for 12 h to obtain β-Ni(OH)2.

[0040] (2) Preparation of ethylenediamine-intercalated crystalline black phosphorus (eda-BP): ethylenediamine-intercalated crystalline black phosphorus was prepared by solvothermal method. First, 0.5 g of red phosphorus was ground into powder in a mortar, and then added to 75 mL of ethylenediamine solution. The mixture was stirred vigorously for 30 min. Then, the mixture was transferred to a 100 mL polytetrafluoroethylene liner and placed in a corresponding stainless steel high-pressure reactor. The stainless steel high-pressure reactor was placed in a constant temperature drying oven and heated at 165 °C for 24 h. After heating, it was rapidly cooled to room temperature with ice water. The precipitate was collected, washed alternately with water and ethanol, and dried under vacuum at 40 °C for 6 h to obtain ethylenediamine-intercalated crystalline black phosphorus.

[0041] (3) Preparation of amorphous black phosphorus: The ethylenediamine molecules between the ethylenediamine-intercalated crystalline black phosphorus layers were removed by hydrothermal reaction, which destroyed its intercalation structure and caused the PP bonds to twist, thereby preparing amorphous black phosphorus; 0.4 g of the ethylenediamine-intercalated crystalline black phosphorus and 70 mL of deionized water were added to a 100 mL polytetrafluoroethylene liner, and the liner was placed in a corresponding stainless steel reactor; the reactor was placed in a constant temperature forced-air drying oven, the temperature was set to 160 ℃, and heated for 24 h; after the reaction was completed, the precipitate was collected, washed with deionized water, and dried under vacuum at 40 ℃ for 12 h to obtain amorphous black phosphorus;

[0042] (4) Preparation of nickel hydroxide / amorphous black phosphorus: Nickel hydroxide / amorphous black phosphorus was prepared by ultrasonic dispersion method. First, the amorphous black phosphorus and the β-nickel hydroxide were ground into powder in a mortar. 5 mg of amorphous black phosphorus powder and 80 mg of β-nickel hydroxide powder were dispersed in 10 mL of ethanol solution. The solution was ultrasonically treated in an ultrasonic cleaner to ensure that the nickel hydroxide and amorphous black phosphorus were fully dispersed and combined to obtain a uniform dispersion. The dispersion was placed in a vacuum drying oven and vacuum dried at 50 °C for 12 h. After grinding, the dried nickel hydroxide / amorphous black phosphorus mixed powder was obtained.

[0043] (5) Preparation of working electrode (β-Ni(OH)2@a-BP): Carbon paper (1.0 cm × 2.0 cm) was placed in anhydrous ethanol and cleaned under ultrasonic conditions for 10 min. Then, the surface was rinsed with deionized water to remove surface oxides and contaminants. It was then dried in a vacuum drying oven at 60 °C to obtain pretreated carbon paper. 5 mg of the nickel hydroxide / amorphous black phosphorus mixed powder was dissolved in 600 μL of anhydrous ethanol, and then 5 μL of Nafion binder was added. A uniform catalyst slurry was obtained by stirring and ultrasonication. Then, 121 μL of the catalyst slurry was uniformly drop-coated onto a 1 cm × 1 cm area of ​​pretreated carbon paper (catalyst loading: 1 mg cm). -2 The nickel hydroxide / amorphous black phosphorus electrode was obtained by using carbon paper as a catalyst support.

[0044] The present invention aims to disrupt the layered lattice of eda-BP, making it amorphous, thereby obtaining amorphous black phosphorus with abundant defects and active sites.

[0045] Further, in steps (1)-(3): the washing conditions are centrifugal washing at a speed of 9000-10000 rpm for 6-10 min.

[0046] Furthermore, the frequency of the ultrasonic treatment in step (4) is 40-60 kHz, and the ultrasonic time is 8-12 min.

[0047] The present invention also discloses a nickel hydroxide / amorphous black phosphorus electrode prepared according to the above preparation method.

[0048] The present invention also discloses an apparatus for electrocatalytic water splitting to produce hydrogen, using the aforementioned nickel hydroxide / amorphous black phosphorus electrode as the electrode material of the apparatus.

[0049] Furthermore, the method for constructing the device for electrocatalytic water splitting to produce hydrogen includes the following steps: using the nickel hydroxide / amorphous black phosphorus electrode as the anode, a graphite rod as the cathode, a 1 M KOH solution as the electrolyte, and a solar panel to provide external energy, a photo-assisted water splitting system is constructed.

[0050] The solar panel can convert the light energy of the light source into electrical energy to power the circuit of the device, thus constructing a highly efficient and stable photovoltaic-electrocatalytic coupling system. Under illumination, the solar panel drives the electrocatalytic water splitting device to achieve simultaneous hydrogen and oxygen production.

[0051] The solar panels used in the following embodiments and comparative examples of the present invention are monocrystalline silicon solar cells.

[0052] Unless otherwise specified, "room temperature" in this invention refers to 10-30°C.

[0053] All raw materials used in the following embodiments and comparative examples of the present invention are commercially available products.

[0054] Example 1

[0055] A method for preparing a nickel hydroxide / amorphous black phosphorus electrode and a photo-assisted electrocatalytic water splitting device using this electrode includes the following steps:

[0056] 1. Preparation of nickel hydroxide / amorphous black phosphorus electrode:

[0057] (1) Preparation of β-Ni(OH)2 sample: β-Ni(OH)2 was synthesized by solvothermal method. First, 0.582 g (2.0 mmol) of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) was dissolved in 40 mL of deionized water and a clear green solution was formed under magnetic stirring. 4 mL of oleylamine was quickly injected into the green solution, and then 20 mL of ethanol was added. The mixture was stirred for 30 min and then transferred to a 100 mL polytetrafluoroethylene liner. The mixture was placed in a corresponding stainless steel autoclave and heated to 190 °C for 16 h. After the reaction was completed, the mixture was naturally cooled to room temperature and the green sample was collected. The sample was washed with cyclohexane, distilled water and ethanol (centrifuged at 9000 rpm for 6 min) and then vacuum dried at 50 °C for 12 h to obtain β-Ni(OH)2.

[0058] (2) Preparation of ethylenediamine-intercalated crystalline black phosphorus (eda-BP): ethylenediamine-intercalated crystalline black phosphorus was prepared by solvothermal method. First, 0.5 g of red phosphorus was ground into powder in a mortar and then added to 75 mL of ethylenediamine solution. The mixture was stirred vigorously for 30 min. Then, the mixture was transferred to a 100 mL polytetrafluoroethylene liner and placed in a corresponding stainless steel high-pressure reactor. The stainless steel high-pressure reactor was placed in a constant temperature drying oven and the temperature was set at 165 °C for 24 h. After heating, it was rapidly cooled to room temperature with ice water. The precipitate was collected and washed alternately with water and ethanol (centrifuged at 9000 rpm for 6 min). Then, it was dried under vacuum at 40 °C for 6 h to obtain ethylenediamine-intercalated crystalline black phosphorus.

[0059] (3) Preparation of amorphous black phosphorus (a-BP): The ethylenediamine molecules between the ethylenediamine-intercalated crystalline black phosphorus were removed by hydrothermal reaction, which destroyed its intercalation structure and caused the PP bond to twist, thereby preparing amorphous black phosphorus; 0.4 g of ethylenediamine-intercalated crystalline black phosphorus and 70 mL of deionized water were added to a 100 mL polytetrafluoroethylene liner, and the liner was placed in the corresponding stainless steel reactor; the reactor was placed in a constant temperature forced-air drying oven, the temperature was set at 160 ℃, and heated for 24 h; after the reaction was completed, the precipitate was collected, washed with deionized water (centrifuged at 9000 rpm for 6 min), and dried under vacuum at 40 ℃ for 12 h to obtain amorphous black phosphorus;

[0060] (4) Preparation of nickel hydroxide / amorphous black phosphorus: Nickel hydroxide / amorphous black phosphorus was prepared by ultrasonic dispersion method. First, amorphous black phosphorus and β-nickel hydroxide were ground into powder in a mortar. 5 mg of amorphous black phosphorus powder and 80 mg of β-nickel hydroxide powder were dispersed in 10 mL of ethanol solution. The solution was placed in an ultrasonic cleaner and ultrasonically treated at 40 kHz for 10 min to ensure that nickel hydroxide and amorphous black phosphorus were fully dispersed and combined to obtain a uniform dispersion. The dispersion was placed in a vacuum drying oven and vacuum dried at 50 ℃ for 12 h. After grinding, dry nickel hydroxide / amorphous black phosphorus mixed powder was obtained.

[0061] (5) Preparation of working electrode: Carbon paper (1.0 cm × 2.0 cm) was placed in anhydrous ethanol and cleaned under ultrasonic conditions for 10 min. Then, the surface was rinsed with deionized water to remove surface oxides and contaminants. It was then dried in a vacuum drying oven at 60 ℃ to obtain pretreated carbon paper. 5 mg of nickel hydroxide / amorphous black phosphorus mixed powder was dissolved in 600 μL of anhydrous ethanol, and then 5 μL of Nafion binder was added. A uniform catalyst slurry was obtained by stirring and ultrasonication. Then, 121 μL of the catalyst slurry was uniformly drop-coated onto a 1 cm × 1 cm area of ​​pretreated carbon paper (catalyst loading: 1 mg cm). -2 Using carbon paper as a catalyst support, a nickel hydroxide / amorphous black phosphorus electrode was obtained after drying, denoted as β-Ni(OH)2@a-BP.

[0062] 2. Preparation of a photo-assisted electrocatalytic water splitting device:

[0063] A commercially available solar panel with an open-circuit voltage (Voc) of 2.2 V was selected and connected to an electrocatalytic water splitting device to provide electrical energy to drive the water splitting reaction, thus constructing a photo-assisted water splitting system. A 150W xenon lamp with an AM1.5 filter was used as a constant light source to illuminate the solar panel, thereby inputting energy.

[0064] A fully enclosed H-type electrolytic cell with gas tubing was used as the anode and cathode regions, respectively. The anode used the aforementioned nickel hydroxide / amorphous black phosphorus electrode, and the cathode used a graphite carbon rod electrode. A 1 M KOH solution was used as the electrolyte. A photocurrent was used to drive the water splitting reaction, thereby generating oxygen at the anode and hydrogen at the cathode. The volume of generated gases was recorded using the water displacement method, resulting in curves showing the change in hydrogen and oxygen production over time.

[0065] Example 2 (Adjusting the loading of nickel hydroxide / amorphous black phosphorus)

[0066] The only difference from Example 1 is that step (5) is modified as follows:

[0067] Carbon paper (1.0 cm × 2.0 cm) was placed in anhydrous ethanol and cleaned ultrasonically for 10 min. The surface was then rinsed with deionized water to remove oxides and contaminants, and dried in a vacuum oven at 60 ℃ to obtain pretreated carbon paper. 5 mg of nickel hydroxide / amorphous black phosphorus mixed powder was dissolved in 600 μL of anhydrous ethanol, followed by the addition of 5 μL of Nafion binder. A homogeneous catalyst slurry was obtained through stirring and ultrasonication. 145.2 μL of this slurry was then uniformly drop-coated four times onto a 1 cm × 1 cm area of ​​pretreated carbon paper (catalyst loading: 1.5 mg / cm²). -2 Using carbon paper as a catalyst support, a nickel hydroxide / amorphous black phosphorus electrode was obtained after drying.

[0068] Example 3 (Adjusting the loading of nickel hydroxide / amorphous black phosphorus)

[0069] The only difference from Example 1 is that step (5) is modified as follows:

[0070] Carbon paper (1.0 cm × 2.0 cm) was placed in anhydrous ethanol and cleaned ultrasonically for 10 min. The surface was then rinsed with deionized water to remove surface oxides and contaminants, and dried in a vacuum oven at 60 ℃ to obtain pretreated carbon paper. 5 mg of nickel hydroxide / amorphous black phosphorus mixed powder was dissolved in 600 μL of anhydrous ethanol, followed by the addition of 5 μL of Nafion binder. A uniform catalyst slurry was obtained through stirring and ultrasonication. Then, 242 μL of the catalyst slurry was uniformly drop-coated four times onto a 1 cm × 1 cm area of ​​pretreated carbon paper (catalyst loading: 2 mg / cm²). -2 Using carbon paper as a catalyst support, a nickel hydroxide / amorphous black phosphorus electrode was obtained after drying.

[0071] Comparative Example 1

[0072] The only difference from Example 1 is that step (4) is modified as follows:

[0073] Preparation of nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus: Nickel hydroxide / amorphous black phosphorus was prepared using an ultrasonic dispersion method. First, ethylenediamine intercalated crystalline black phosphorus and β-nickel hydroxide were separately ground into powder in a mortar. 5 mg of ethylenediamine intercalated crystalline black phosphorus powder and 80 mg of β-nickel hydroxide powder were dispersed in 10 mL of ethanol solution. The solution was ultrasonically treated at 40 kHz for 10 min to obtain a uniform dispersion. The dispersion was then placed in a vacuum drying oven and vacuum dried at 50 ℃ for 12 h. After grinding, a dry nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus mixed powder was obtained. The final nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode prepared from this mixed powder was designated β-Ni(OH)2@eda-BP.

[0074] Comparative Example 2

[0075] The only difference from Example 1 is that the anode material in step (2) is changed from a nickel hydroxide / amorphous black phosphorus electrode to an equal mass of β-nickel hydroxide electrode (denoted as β-Ni(OH)2). The specific preparation method of the nickel hydroxide electrode is as follows:

[0076] Carbon paper (1.0 cm × 2.0 cm) was placed in anhydrous ethanol and cleaned under ultrasonic conditions for 10 min. Then, the surface was rinsed with deionized water to remove surface oxides and contaminants. It was then dried in a vacuum drying oven at 60 °C to obtain pretreated carbon paper. 5 mg of β-nickel hydroxide from step (1) of Example 1 was taken, ground into powder, dissolved in 600 μL of anhydrous ethanol, and then 5 μL of Nafion binder was added. A uniform catalyst slurry was obtained by stirring and ultrasonication. Then, 121 μL of the catalyst slurry was uniformly drop-coated onto a 1 cm × 1 cm area of ​​pretreated carbon paper. The carbon paper was used as a catalyst support. After drying, a β-nickel hydroxide electrode was obtained.

[0077] Effect verification

[0078] Figure 1 The images show the XRD patterns of β-nickel hydroxide and ethylenediamine-intercalated crystalline black phosphorus, amorphous black phosphorus, and nickel hydroxide / amorphous black phosphorus mixed powders prepared in Example 1, and the nickel hydroxide / ethylenediamine-intercalated crystalline black phosphorus mixed powders prepared in Comparative Example 1.

[0079] Through the Figure 1Analysis revealed that the prepared β-nickel hydroxide sample exhibited distinct diffraction peaks at approximately 19.2°, 32.9°, 38.3°, and 58.5° at 2θ angles. These peaks are consistent with those of nickel hydroxide (Ni(OH)2) (JCPDS No. 14-0117) known in the standard database. When β-nickel hydroxide was combined with ethylenediamine-intercalated crystalline black phosphorus and amorphous black phosphorus, the resulting nickel hydroxide / ethylenediamine-intercalated crystalline black phosphorus, in addition to exhibiting the characteristic diffraction peaks of nickel hydroxide / amorphous black phosphorus, showed weak diffraction peaks at 10.3° and 17.7°. This phenomenon may be due to the low loading of ethylenediamine-intercalated crystalline black phosphorus. Since amorphous black phosphorus is an amorphous material, the positions of the diffraction peaks in the nickel hydroxide / amorphous black phosphorus sample did not change significantly compared to the β-nickel hydroxide matrix.

[0080] Figure 2 These are transmission electron microscopy (TEM) images of (a) β-nickel hydroxide, (c) nickel hydroxide / amorphous black phosphorus mixed powder prepared in Example 1, and (b) nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus mixed powder prepared in Comparative Example 1.

[0081] TEM images of β-nickel hydroxide show that it exhibits a hexagonal sheet-like structure with a size of approximately 100 nm. TEM images of the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus mixed powder and the nickel hydroxide / amorphous black phosphorus mixed powder show that the morphology of the composite β-nickel hydroxide nanosheets remains largely unchanged, the hexagonal sheet-like structure is still clearly visible, and there is close contact between β-nickel hydroxide and ethylenediamine intercalated crystalline or amorphous black phosphorus, indicating that there is a certain interfacial interaction between the two.

[0082] Figure 3 These are Raman spectra of the β-nickel hydroxide, nickel hydroxide / amorphous black phosphorus mixed powder prepared in Example 1, and the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus mixed powder prepared in Comparative Example 1.

[0083] Raman spectra of nickel hydroxide / amorphous black phosphorus, nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus, and β-nickel hydroxide show a 3580 cm⁻¹ pattern. -1 The characteristic peaks of β-nickel hydroxide correspond to nickel hydroxide. Furthermore, β-nickel hydroxide shows characteristic peaks at 320 and 440 cm⁻¹. -1 Characteristic peaks corresponding to Ni(OH)₂ are present at [value missing], but at [value missing] in nickel hydroxide / amorphous black phosphorus and nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus, they are difficult to observe due to superposition with the characteristic peaks of black phosphorus. The peaks at 362 and 466 cm⁻¹ correspond to Ni(OH)₂. -1 Characteristic peaks exist at these locations, and these peaks correspond to black phosphorus A, respectively. 1g and A 2gPhonon vibration modes all exhibit typical characteristic peaks of black phosphorus materials. The appearance of these characteristic peaks indicates that nickel hydroxide / amorphous black phosphorus and nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus retain the inherent structural characteristics of black phosphorus, suggesting that the structure of black phosphorus was not destroyed during the synthesis process.

[0084] The electrochemical performance of the working electrode materials prepared in each embodiment and comparative example was tested using the following method: A CHI 660E electrochemical workstation from Shanghai Chenhua Company was used for the electrochemical performance testing, and the test system was a standard three-electrode system; the working electrode was the product of step (5) in each embodiment and comparative example, the reference electrode was a silver / silver chloride (Ag / AgCl) electrode, and the counter electrode was a graphite rod electrode; the electrochemical test used 1 M potassium hydroxide (KOH) solution as the electrolyte, at a voltage of 5 mV s. -1 LSV testing was performed at a scanning rate (potential window of 1.2-2.0 V for electrochemical scanning) to obtain the OER polarization curve of the electrode material. The overpotential of the catalyst was determined by the polarization curve, and the electrocatalytic performance, such as the Tafel slope, was calculated. In impedance mode, in-situ electrochemical impedance spectroscopy (EIS) was performed to obtain the Nyquist plot and the corresponding phase angle changes. The stability of the electrode material was observed by measuring the change of current on the electrode over time using the chronoamperometry method.

[0085] Figure 4 The OER performance of the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 in 1 M KOH electrolyte; wherein, (a) at a scan rate of 5 mV s -1 LSV test curve, (b) current density of 10 mA cm⁻¹ -2 (c) Overpotential, (d) Tafel slope, (e) Current density of 10 mA cm⁻¹ -2 Electrochemical stability at that time.

[0086] Depend on Figure 4 It was found that all three samples exhibited metal oxidation peaks before the OER reaction began. OER activity analysis revealed that the catalytic performance of nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus and nickel hydroxide / amorphous black phosphorus was significantly improved compared to β-nickel hydroxide. Among them, nickel hydroxide / amorphous black phosphorus achieved a higher current density at the same voltage; at a current density of 10 mA cm⁻¹... -2At that time, the overpotential of nickel hydroxide / amorphous black phosphorus was only 332 mV, a decrease of 72 mV compared to β-nickel hydroxide. The overpotential of nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus also improved compared to β-nickel hydroxide, decreasing to 364 mV; the Tafel slope of nickel hydroxide / amorphous black phosphorus was 145.0 mV·dec. -1 The crystalline black phosphorus with a nickel hydroxide / ethylenediamine intercalation layer has a lower concentration (158.1 mV·dec). -1 ), far lower than β-nickel hydroxide (213.4 mV·dec). -1 This indicates that the catalytic reaction kinetics of nickel hydroxide / amorphous black phosphorus are more rapid; the catalyst was chronotropically controlled at 10 mA cm⁻¹ using amperometric chronometry. -2 The electrochemical stability under current density was tested over a long period of 120 h. The stability of crystalline black phosphorus with nickel hydroxide / ethylenediamine intercalation was improved compared with that of β-nickel hydroxide. However, since the intrinsic stability of crystalline black phosphorus with ethylenediamine intercalation is worse than that of amorphous black phosphorus, it is prone to hydrolysis in the OER reaction, resulting in large fluctuations during the stability test.

[0087] Figure 5 The Ni concentration was determined by ICP-MS after the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 were reacted in 1 M KOH electrolyte for 2 h.

[0088] Depend on Figure 5 It can be seen that the Ni concentration in the electrolyte after the nickel hydroxide / amorphous black phosphorus reaction is only 0.35 mg / L. -1 The crystalline black phosphorus with a lower concentration than that of nickel hydroxide / ethylenediamine intercalation (0.71 mg L) -1 ), far lower than β-nickel hydroxide (1.05 mg / L). -1 The nickel hydroxide / amorphous black phosphorus catalyst demonstrated good resistance to dissolution and exhibited high stability. The results indicate that the composite material of black phosphorus can, to a certain extent, inhibit the excessive oxidation of nickel.

[0089] Figure 6 The LSV curves of the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2, as well as the potential difference from their oxidation peaks to the OER initiation potential, are shown.

[0090] Observation of the LSV curves reveals that the composite black phosphorus material effectively reduces the reaction overpotential of β-nickel hydroxide, and the high electron transport rate of black phosphorus accelerates the water splitting reaction. Simultaneously, comparing the oxidation peaks of the three materials shows that the metal oxidation peak potential and current density (oxidation peak area) in the LSV curves of the crystalline black phosphorus and amorphous black phosphorus samples doped with ethylenediamine intercalation are larger. This indicates that the β-nickel hydroxide in these samples undergoes a more vigorous initial electrochemical reconstruction process, resulting in the formation of more active materials on the catalyst electrode surface. The sufficient coverage of these active materials also helps to prevent excessive oxidation of the internal structure of the electrode, thus preventing nickel (Ni) loss. Furthermore, comparing the potential difference from the oxidation peak to the OER initiation potential of the three catalysts reveals that nickel hydroxide / amorphous black phosphorus has the smallest potential difference (128 mV), which is 58% shorter than that of β-nickel hydroxide. This smaller potential difference allows for timely provision of electrons to the metal, effectively preventing excessive oxidation.

[0091] Figure 7 The Nyquist plots and corresponding phase angle changes obtained by electrochemical impedance spectroscopy (EIS) of the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 under a bias voltage of 1.2 V-1.7 V are shown. Among them, (a), (b), and (c) are the Nyquist plots of the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode, the β-nickel hydroxide electrode, and the nickel hydroxide / amorphous black phosphorus electrode, respectively, and (d) shows the phase angle change.

[0092] Depend on Figure 7It can be seen that in the Bode plots at different potentials, the peaks appearing in the low-frequency and high-frequency regions are attributed to electron transfer occurring at the interface between the electrolyte and the working electrode, and electron transfer occurring within the electrode, respectively. In the low-frequency region at low voltage, all three electrodes exhibit a large phase difference, indicating significant resistance before OER begins. As the voltage increases, the characteristic peaks shift towards the mid-frequency region, indicating that electron transfer begins between the electrode and the electrolyte. Both the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus and the nickel hydroxide / amorphous black phosphorus exhibit significant negative phase angle growth in the mid-frequency region, indicating that both samples possess good reaction kinetics. The β-nickel hydroxide electrode sample shows large phase angles in both the high-frequency and low-frequency regions, indicating significant resistance both within the electrode and at the electrode-electrolyte interface. Observing the phase angles reveals that the phase angle changes of nickel hydroxide / amorphous black phosphorus at different potentials are relatively smooth and the amplitude of phase angle changes is small, indicating stable interfacial capacitance and efficient charge transport. Impedance analysis of samples under different voltages revealed that the addition of amorphous black phosphorus and ethylenediamine-intercalated crystalline black phosphorus accelerated charge transport during the reaction process, effectively enhancing the reaction kinetics of β-nickel hydroxide in the OER process.

[0093] Figure 8 This is a schematic diagram of the structure of the photo-assisted electrocatalytic water splitting device of the present invention.

[0094] Depend on Figure 8 As can be seen, the photo-assisted electrocatalytic water splitting device of the present invention consists of a constant light source, a solar panel, an electrochemical workstation, and a three-electrode electrolytic cell. The constant light source provides stable illumination conditions to simulate sunlight intensity; the solar panel generates a photoelectric potential difference under illumination, providing a driving voltage for the electrochemical reaction; the electrochemical workstation controls and detects electrochemical parameters such as current and voltage in the reaction system; the electrolytic cell is equipped with an anode, a cathode, and a reference electrode, wherein the anode uses a nickel hydroxide / amorphous black phosphorus electrode, and a graphite carbon rod is used as the cathode to achieve the catalytic conversion of the target reaction. Through the direct coupling of the solar panel and the electrocatalytic system, the electrochemical reaction can be driven without an external bias voltage, realizing the efficient conversion of light energy into chemical energy.

[0095] Figure 9 The current-voltage (JV) characteristic curves of the photo-assisted electrocatalytic water splitting devices prepared using the nickel hydroxide / amorphous black phosphorus electrode in Example 1, the nickel hydroxide / ethylenediamine intercalated crystalline black phosphorus electrode in Comparative Example 1, and the β-nickel hydroxide electrode in Comparative Example 2 are shown.

[0096] Figure 9These are the JV characteristic curves of the electrode materials prepared in each embodiment and comparative example after being connected to a solar cell, under two-electrode conditions. Using solar cell-electrocatalytic coupling, a nickel hydroxide / amorphous black phosphorus electrode achieved a JV value of 5.28 mA cm⁻¹ under zero bias conditions. -2 (J) op ), thereby generating the corresponding solar energy to η STH It is 6.49%. (The η value is different from that of β-nickel hydroxide.) STH Compared to (3.42%), it increased significantly by 89.8%.

[0097] Figure 10 The graph shows the H2 and O2 production curves of the photo-assisted electrocatalytic water splitting device prepared using the nickel hydroxide / amorphous black phosphorus electrode in Example 1 under a 0 V bias voltage.

[0098] Figure 10 In this study, a photovoltaic-electrocatalytic system was used to conduct durability tests on nickel hydroxide / amorphous black phosphorus at 15 °C and in 1 MKOH electrolyte under an applied bias voltage of 0 V. The volume of generated gas was recorded using the water displacement gas collection method. Comprehensive analysis of the changes in hydrogen and oxygen production over time revealed that during 5 hours of electrolysis under illumination, the volume of generated gas remained approximately 2:1 (hydrogen to oxygen), and the Faraday efficiency was close to 100%.

[0099] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a nickel hydroxide / amorphous black phosphorus electrode, characterized by, The method comprises the following steps: adding red phosphorus powder into ethylenediamine, carrying out intercalation reaction to obtain ethylenediamine intercalated crystalline black phosphorus; mixing the ethylenediamine intercalated crystalline black phosphorus with water, carrying out heating reaction to obtain amorphous black phosphorus; mixing the amorphous black phosphorus with β-nickel hydroxide powder in a dispersant to obtain a dispersion liquid, carrying out drying treatment to obtain nickel hydroxide / amorphous black phosphorus mixed powder; loading the nickel hydroxide / amorphous black phosphorus mixed powder on an electrode substrate to obtain the nickel hydroxide / amorphous black phosphorus electrode.

2. The production method according to claim 1, characterized by, The amount ratio of the red phosphorus powder to the ethylenediamine is 0.5 g:75 mL; the intercalation reaction is carried out at 165 ℃ for 24 h.

3. The preparation method according to claim 1, characterized in that, The amount ratio of the ethylenediamine intercalated crystalline black phosphorus to water is 0.4 g:70 mL; the heating reaction is carried out at 160 ℃ for 24 h.

4. The method of claim 1, wherein, The amount ratio of the amorphous black phosphorus, the β-nickel hydroxide and the dispersant is 5 mg:80 mg:10 mL; the dispersant is ethanol; the drying treatment is vacuum drying at 50 ℃ for 12 h.

5. The preparation method according to claim 1, characterized in that, The electrode substrate is carbon paper, and the loading amount of the nickel hydroxide / amorphous black phosphorus mixed powder on the electrode substrate is 1 mg·cm -2 .

6. The method of claim 1, wherein, The preparation method of the β-nickel hydroxide powder comprises the following steps: dissolving 2 mmol of nickel nitrate into 40 mL of water, then adding 4 mL of oleylamine, 20 mL of ethanol, heating at 190 ℃ for 16 h, and crushing to obtain the β-nickel hydroxide powder.

7. A nickel hydroxide / amorphous black phosphorus electrode prepared by the preparation method according to any one of claims 1-6.

8. Use of the nickel hydroxide / amorphous black phosphorus electrode according to claim 7 as an anode in the field of electrocatalytic water splitting.

9. A device for electrocatalytic water splitting, characterized by, The nickel hydroxide / amorphous black phosphorus electrode according to claim 7 is used as anode material of the device.

10. The apparatus of claim 9, wherein, A solar cell panel is connected in the device, and the solar cell panel is used to convert light energy into electric energy to supply power to the circuit of the device. A solar cell panel is connected in the device, and the solar cell panel is used to convert light energy into electric energy to supply power to the circuit of the device.

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