Preparation method and application of photocatalytic full-water-splitting film based on electrostatic spinning

Abstract

The invention relates to a preparation method of a photocatalytic full-decomposition water film based on electrostatic spinning, and the preparation method comprises the following steps: S1, taking a carbon nitride precursor as a raw material, and carrying out secondary calcination to obtain an ultrathin g-C3N4 nanosheet; and carrying out electrostatic self-assembly on Co-coated BCN obtained by carrying out boron doping and cobalt compounding on the g-C3N4 and acidized Pt-coated CN obtained by carrying out platinum loading and acidizing treatment on the Co-coated BCN and the g-C3N4, so as to obtain the Co-coated BCN / Pt-coated CN photocatalyst. And S2, placing the Co-coated BCN / Pt-coated CN photocatalyst in an organic solvent, carrying out ultrasonic treatment, adding PAN, continuously carrying out ultrasonic treatment to obtain an electrostatic spinning solution, and carrying out an electrostatic spinning technology to obtain the photocatalytic full-decomposition water film. A carbon nitride precursor is used as a raw material, a carbon nitride-based photocatalyst Co (at) BCN / Pt (at) CN is obtained through modification means such as boron doping, cobalt compounding and platinum loading, the carbon nitride-based photocatalytic full-decomposition water film with high photocatalytic activity is prepared by combining an electrostatic spinning technology, and the carbon nitride-based photocatalytic full-decomposition water film can directly drive a water decomposition reaction under visible light to achieve efficient hydrogen production and oxygen production.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic water splitting, and particularly to a preparation method and application of a photocatalytic overall water splitting film based on electrospinning. Background Art

[0002] With the increasingly serious global energy crisis and environmental pollution problems, the development of new, efficient, and sustainable energy conversion technologies has become an urgent need. Photocatalytic overall water splitting technology has attracted much attention because it can directly convert solar energy into chemical energy (hydrogen energy). The core of this technology lies in the developed photocatalyst that can effectively separate the electrons and holes generated after absorbing sunlight and migrate them to the surface reaction sites to independently drive the hydrogen production and oxygen production reactions of water decomposition. As a new type of non-metallic photocatalytic material, carbon nitride shows great potential due to its unique electronic structure and excellent chemical stability. To meet the requirements of photocatalytic overall water splitting reaction, it is usually necessary to load suitable hydrogen production and oxygen production co-catalysts on the surface of carbon nitride. These co-catalysts not only help to separate and migrate photo-generated electrons and holes, but also significantly reduce the activation energy of the hydrogen production and oxygen production reactions of water hydrolysis. However, traditional powder carbon nitride still faces many challenges in practical applications. First, the powder material is prone to agglomeration in the reaction system, resulting in a decrease in its actual reaction surface area and active sites, thus reducing the photocatalytic performance. Second, after the reaction, it is difficult to separate and recycle the powder material, which not only increases the operation cost but also limits its practical application in industrial production. Therefore, developing new preparation methods to realize the deviceization of carbon nitride has become the key to solving the above problems. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a preparation method and application of a photocatalytic overall water splitting film based on electrospinning. The preparation method of the present invention is simple, low-cost, easy to scale up production and promotion, and provides an efficient and sustainable solution for the practical application of photocatalytic overall water splitting technology.

[0004] The technical solution adopted by the present invention is as follows:

[0005] On the one hand, the present invention provides a preparation method of a photocatalytic overall water splitting film based on electrospinning, including the following steps:

[0006] S1. Using a carbon nitride precursor as a raw material, obtaining ultrathin g-C3N4 nanosheets through secondary calcination;

[0007] Subjecting the g-C3N4 to boron doping and cobalt complexing to obtain Co@BCN, and subjecting the g-C3N4 to platinum loading and acidification treatment to obtain acidified Pt@CN, and performing electrostatic self-assembly to obtain a Co@BCN / Pt@CN photocatalyst;

[0008] S2. Place the Co@BCN / Pt@CN photocatalyst in an organic solvent, sonicate it, then add PAN and continue to sonicate to obtain an electrospinning solution. Through electrospinning technology, a photocatalytic overall water splitting membrane is obtained.

[0009] A preparation method of a photocatalytic overall water splitting membrane based on electrospinning proposed by the present invention uses a carbon nitride precursor as a raw material. Through modification means such as boron doping, cobalt compounding, and platinum loading, a carbon nitride-based photocatalyst Co@BCN / Pt@CN is obtained. Combining electrospinning technology, a carbon nitride-based photocatalytic overall water splitting membrane with high photocatalytic activity is prepared. It can directly drive the water splitting reaction under visible light to achieve efficient hydrogen production and oxygen production. Specifically, the carbon nitride-based photocatalyst has a unique electronic structure and energy band configuration. Its heptazine-based π-conjugated system can efficiently absorb sunlight and generate photogenerated electrons and holes. At the same time, its conduction band and valence band positions are appropriate, which can simultaneously meet the electrode potential requirements for the reduction (hydrogen production) and oxidation (oxygen production) reactions of water, thus realizing the photocatalytic overall water splitting reaction. By combining boron doping, cobalt compounding, and platinum loading, the hydrogen production and oxygen production cocatalysts are integrated, significantly reducing the recombination probability of photogenerated electrons and holes, accelerating the separation and migration of electron-hole pairs, and optimizing the kinetic process of the surface hydrolysis reaction, thereby greatly improving the efficiency of the photocatalytic reaction. In addition, using electrospinning technology to spin the carbon nitride-based photocatalyst powder into nanofibers, these nanofibers are intertwined to form a porous network structure, which not only greatly increases the specific surface area of the membrane but also exposes more reactive sites, can capture and convert light energy more efficiently, promote the adsorption and dissociation of water molecules, and further improve the performance of photocatalytic overall water splitting. In addition, this membrane structure effectively solves the problems of easy agglomeration and difficult separation and recovery of traditional powdered carbon nitride, providing convenience for its practical application and industrial production.

[0010] Preferably, in step S1, the carbon nitride precursor is dicyandiamide;

[0011] The program of the secondary calcination is: first heat up to 550 °C at a rate of 5 °C / min and calcine for 4 h, then heat up to 590 °C at the same rate and calcine for 4 h.

[0012] Preferably, in step S1, the boron doping and cobalt compounding specifically include the following steps: thoroughly grind and mix the g-C3N4 with NaBH4, calcine it in an inert gas atmosphere, wash the obtained product with ethanol and deionized water in turn, perform ultrasonic stirring and centrifugation multiple times, and dry it to obtain BCN;

[0013] Place the BCN in a cobalt hexahydrate nitrate solution, sonicate it, then add ammonia monohydrate and continue to sonicate, filter and dry to obtain the Co@BCN.

[0014] More preferably, the mass ratio of the g-C3N4 to the NaBH4 is 1:4;

[0015] The calcination procedure is as follows: heating to 400 °C at a rate of 5 °C / min and calcining for 1 h;

[0016] The concentration of the cobalt nitrate hexahydrate solution is 0.015 - 0.025 M, and the mass-volume ratio of the BCN, the cobalt nitrate hexahydrate solution to the ammonia monohydrate is 0.05 g: 800 μL: 0.5 mL.

[0017] Preferably, in step S1, the platinum loading and acidification treatment specifically include the following steps: adding the g-C3N4, the sacrificial agent and chloroplatinic acid into water by using a water photolysis system, performing a reduction reaction under simulated visible light irradiation, collecting the product and drying it to obtain Pt@CN;

[0018] Placing the Pt@CN in a mixed solution of hydrochloric acid and deionized water, and obtaining acidified Pt@CN through ultrasonic treatment, static stirring, suction filtration and drying.

[0019] More preferably, the sacrificial agent is methanol;

[0020] The dosage of the chloroplatinic acid accounts for 1 - 3% of the mass of the g-C3N4 in terms of the platinum loading amount;

[0021] The conditions of the reduction reaction are: irradiating under a xenon lamp with a condensing water at 10 °C, a lamp current of 15 A and a wavelength of 420 - 800 nm for 2 h;

[0022] The mass-volume ratio of the Pt@CN, the hydrochloric acid to the deionized water is 0.05 g: 30 mL: 170 mL.

[0023] Preferably, in step S1, the electrostatic self-assembly specifically includes the following steps: placing the acidified Pt@CN in deionized water, performing ultrasonic treatment, then adding the Co@BCN, continuing ultrasonic treatment, static stirring, rotary evaporation to remove the solvent, and drying to obtain the Co@BCN / Pt@CN photocatalyst.

[0024] More preferably, the mass ratio of the Co@BCN to the acidified Pt@CN is 1:1.

[0025] Preferably, in step S2, the mass-volume ratio of the Co@BCN / Pt@CN, the organic solvent to the PAN is 0.05 - 0.2 g: 5 mL: 0.24 g;

[0026] The ultrasonic treatment time is 5 h for both;

[0027] The parameters of the electrospinning are as follows: the spinning voltage is 20 kV, the rotating speed of the roller is 50 r / min, the feeding flow rate of the solution is 1 mL / h, and the distance between the spinneret and the roller is 20 cm.

[0028] On the other hand, the present invention provides an application of a photocatalytic overall water splitting film based on electrospinning prepared by the preparation method described in any one of the above technical solutions in photocatalytic overall water splitting for hydrogen and oxygen production.

[0029] The photocatalytic overall water splitting film based on electrospinning provided by the present invention shows broad application prospects in environmental governance fields such as overall water splitting for hydrogen and oxygen production under visible light, air purification, etc., and provides an efficient and sustainable solution for clean energy production and environmental protection. Description of the Drawings

[0030] Figure 1 It is a scanning electron microscope image of the Co@BCN / Pt@CN photocatalytic overall water splitting film synthesized in Example 1;

[0031] Figure 2 It is an XRD pattern of the Co@BCN / Pt@CN photocatalytic overall water splitting film synthesized in Example 1;

[0032] Figure 3 It is an FT-IR pattern of the Co@BCN / Pt@CN photocatalytic overall water splitting film synthesized in Example 1;

[0033] Figure 4 It is a tensile curve of the Co@BCN / Pt@CN photocatalytic overall water splitting film synthesized in Example 1;

[0034] Figure 5 It is a photocatalytic overall water splitting hydrogen and oxygen production activity test pattern of the Co@BCN / Pt@CN photocatalytic overall water splitting film synthesized in Example 1;

[0035] Figure 6 It is a comparative diagram of the photocatalytic overall water splitting cycle experiment between the Co@BCN / Pt@CN photocatalytic overall water splitting film (spinning film photocatalyst) synthesized in Example 1 and the pure PAN film loaded with the powder Co@BCN / Pt@CN photocatalyst (PAN + powder photocatalyst) synthesized in Comparative Example 1. Detailed Description of the Invention

[0036] In order to better understand the above technical solutions, the exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and the scope of the present invention can be fully conveyed to those skilled in the art.

[0037] Example 1

[0038] A preparation method of a photocatalytic overall water splitting membrane based on electrospinning, comprising the following steps:

[0039] S1. Using 5.0000 g of a carbon nitride precursor (dicyandiamide) as a raw material, ultrathin g-C3N4 nanosheets (CN) are obtained through secondary calcination; the program of the secondary calcination is: first, heat up to 550 °C at a rate of 5 °C / min and calcine for 4 h, and then heat up to 590 °C at the same rate and calcine for 4 h.

[0040] Co@BCN obtained by boron doping and cobalt compounding of g-C3N4 and acidified Pt@CN obtained by platinum loading and acidification treatment of g-C3N4 are subjected to electrostatic self-assembly to obtain a Co@BCN / Pt@CN photocatalyst;

[0041] Among them, boron doping and cobalt compounding specifically include the following steps: 0.4 g of g-C3N4 and 0.16 g of NaBH4 are fully ground and mixed, and in an inert gas (nitrogen) atmosphere, heat up to 400 °C at a rate of 5 °C / min and calcine for 1 h. The obtained product is washed successively with ethanol and deionized water, ultrasonically stirred for 5 min and centrifuged multiple times, and dried at 80 °C for 24 h to obtain boron-doped nitrogen-deficient g-C3N4 nanosheets (BCN);

[0042] 0.05 g of BCN is placed in 800 μL of a 0.0202 M cobalt nitrate hexahydrate solution, ultrasonically treated for 30 min, then 0.5 mL of ammonia monohydrate is added, and ultrasonically treated for another 5 min. After suction filtration and drying at 80 °C for 48 h, a Co@BCN oxygen evolution photocatalyst is obtained;

[0043] Among them, platinum loading and acidification treatment specifically include the following steps: Using a water splitting system, 0.05 g of g-C3N4, 20 mL of a sacrificial agent (methanol), and 1.5 mg of chloroplatinic acid (1 wt% Pt loading) are added to 100 mL of water, and a reduction reaction is carried out under simulated visible light irradiation. The product is collected and dried at 80 °C for 48 h to obtain Pt@CN; the conditions of the reduction reaction are: irradiate under a xenon lamp with a condensing water temperature of 10 °C, a lamp current of 15 A, and a wavelength of 420 - 800 nm for 2 h;

[0044] 0.05 g of Pt@CN is placed in a mixed solution of 30 mL of hydrochloric acid and 170 mL of deionized water, ultrasonically treated for 1 h, stirred statically for 10 h, suction filtered, and dried to obtain an acidified Pt@CN hydrogen evolution photocatalyst;

[0045] Among them, the electrostatic self-assembly specifically includes the following steps: Place the acidified Pt@CN in 200 mL of deionized water, ultrasonicate for 20 min, add an equal mass of Co@BCN, ultrasonicate for 30 min, stir statically for 8 h, rotary evaporate to remove the solvent, and dry at 80 °C for 48 h to obtain the powdery Co@BCN / Pt@CN photocatalyst.

[0046] S2. Place 0.1 g of the Co@BCN / Pt@CN photocatalyst in 5 mL of an organic solvent (DMF), ultrasonicate for 5 h, then add 0.24 g of PAN, and continue ultrasonication for 5 h to obtain an electrospinning solution. Through electrospinning technology, a photocatalytic overall water splitting membrane is obtained;

[0047] Among them, the parameters of electrospinning are: the spinning voltage is 20 kV, the roller rotation speed is 50 r / min, the feeding flow rate of the solution is 1 mL / h, and the distance between the spinneret and the roller is 20 cm.

[0048] Comparative Example 1

[0049] The main difference between this comparative example and Example 1 lies in the different combination methods of the Co@BCN / Pt@CN photocatalyst and the PAN membrane: In this comparative example, the same electrospinning process as in Example 1 is used to first synthesize a pure PAN thin film, and then the same mass of the powdery Co@BCN / Pt@CN photocatalyst is loaded onto the PAN thin film by suction filtration, denoted as PAN + powdery photocatalyst.

[0050] Performance Test

[0051] The electrospun film of the Co@BCN / Pt@CN photocatalyst synthesized in Example 1 was subjected to multi-dimensional characterization and analysis, and the results were recorded in Figures 1 - 5 .

[0052] The microscopic morphology of the electrospun film of the Co@BCN / Pt@CN catalyst synthesized in Example 1 was observed, and the results were recorded in Figure 1 . It can be seen from the observation under a field emission scanning electron microscope at a magnification of 5000 times that the PAN matrix presents a continuous fibrous structure with uniform distribution. The fiber diameter is about 0.1 μm, the surface is smooth and there are no obvious defects, indicating that the electrospinning process has successfully achieved the efficient fiber formation of PAN. Porous flocculent carbon nitride aggregates are tightly coupled to the surface of the PAN fiber, and its morphology presents an irregular porous network structure. The porous flocculent morphology of carbon nitride significantly increases the specific surface area of the material. At the same time, its tight coupling with the PAN fiber may optimize the interfacial transport efficiency of photogenerated carriers, thereby enhancing the photocatalytic activity of the composite material in the photocatalytic water splitting reaction. This structural feature provides a key morphological basis for subsequent photocatalytic performance research.

[0053] The Co@BCN / Pt@CN catalyst spinning film synthesized in Example 1 was subjected to XRD test and recorded in Figure 2 . It can be seen that the sample exhibits significant diffraction peaks at 17.1° and 27.9°, corresponding to the diffraction of the (100) and (110) crystal planes of polyacrylonitrile (PAN), respectively, which is consistent with the literature. The peaks belonging to the (100) and (002) crystal planes of carbon nitride are not clearly shown in this figure. This may be due to the low content of carbon nitride and the fact that most of the carbon nitride is coated by PAN after carbon nitride is coupled with PAN material, so the diffraction peak intensity is weak, which also indicates that carbon nitride may exist in the PAN matrix in an amorphous or nano-dispersed form.

[0054] Figure 3 This is the FT-IR image of the Co@BCN / Pt@CN catalyst spinning film synthesized in Example 1. -1 (-CH2 asymmetric stretching vibration), 2240cm -1 (C≡N stretching vibration) and 1448cm -1 (-CH2 bending vibration), these three characteristic peaks belong to the fingerprint recognition area of ​​PAN. 810cm -1 The strong peak at 1323-1250cm -1 The double peak in the interval is attributed to the stretching vibration of CNC bonds, 1635cm -1 The peaks are derived from the vibration of CN bonds, while the peaks at 1416-1570cm -1 The series of peaks in the range of 3000-3600cm -1 The broad peak reveals the vibration information of the terminal -NH2 group and NH bond in the material, indicating that the catalyst has the typical characteristics of carbon nitride polymers. This spectral analysis provides a key experimental basis for the composition confirmation of the composite material and subsequent structure-activity relationship research.

[0055] The tensile strength test of the spun film Co@BCN / Pt@CN photocatalyst synthesized in Example 1 was further performed, and the results were recorded as follows: Figure 4 .from Figure 4It can be seen that the material exhibits a linear stress response in the initial elastic stage (strain 0 - 1.5%), and enters the plastic deformation stage after reaching the yield strength of 1.5 MPa. When the strain exceeds 2.5%, the propagation of microcracks causes a sudden drop in stress. Finally, the tensile strength is measured to be 1.236 MPa, and the elongation at break is 2.9%. The material maintains an effective stress-bearing capacity within a strain range of 2.5% before fracture. Combining its strength index of 1.2 MPa, it can meet the tolerance requirements of fluid shear force (usually <0.5 MPa) and periodic mechanical loads during the operation of the photocatalytic membrane reactor. It can withstand a certain amount of mechanical stress without damage in practical application scenarios such as photocatalytic reactors, ensuring the operational stability and durability of the membrane catalyst.

[0056] The photocatalytic performance of the electrospun thin film Co@BCN / Pt@CN photocatalyst synthesized in Example 1 for overall water splitting to produce hydrogen and oxygen was tested, and the results were recorded as Figure 5 . From Figure 5 it can be seen that this thin film material can decompose water to produce hydrogen and oxygen in pure water.

[0057] The electrospun thin film Co@BCN / Pt@CN photocatalyst synthesized in Example 1 and the pure PAN thin film loaded with powdered Co@BCN / Pt@CN photocatalyst synthesized in Comparative Example 1 were subjected to a photocatalytic overall water splitting cycle experiment test. During the performance test, each illumination lasted for 2 h, then the thin film was taken out, washed with water, dried, and then placed back into the reactor for performance testing.

[0058] From Figure 6 it can be seen that the electrospun thin film Co@BCN / Pt@CN photocatalyst in Example 1 of the present invention has stable cycle performance. For the membrane material in Comparative Example 1, although its performance was relatively high in the first round of experiments, its cycle performance was poor. This may be because during the water washing process, in Comparative Example 1, only powdered photocatalyst was simply loaded on the surface after film formation. This simple physical loading method caused the powdered photocatalyst to be unable to adhere firmly to the PAN thin film, easily losing the photocatalytic active components and resulting in serious deactivation, further demonstrating the superiority of the method of electrospinning the carbon nitride powdered photocatalyst into a fiber membrane in the present invention.

[0059] In summary, the present invention constructs a carbon nitride-based photocatalytic overall water splitting membrane using electrospinning technology. On the one hand, through the combination of boron doping, cobalt complexation and platinum loading: Boron doping effectively broadens the light absorption range of carbon nitride, enabling it to capture sunlight with a wider range of wavelengths, significantly improving the utilization efficiency of solar energy; cobalt complexation optimizes the electronic structure of carbon nitride, promotes the separation of photogenerated carriers, reduces the activation energy of the water splitting oxygen evolution reaction, and thus greatly improves the photocatalytic oxygen evolution activity; while loading the platinum cocatalyst further accelerates the rate of photogenerated carriers participating in chemical reactions, significantly enhancing the hydrogen production efficiency. The three work together to achieve efficient separation of photogenerated carriers and activation of double reaction sites. On the other hand, through the electrospinning process, the powder is transformed into a three-dimensional porous nanofiber membrane, increasing the density of active sites. At the same time, it breaks through the bottleneck of the traditional powder being prone to agglomeration and difficult to recycle, realizing the stable immobilization of the catalyst. The electrospinning-based photocatalytic overall water splitting membrane of the present invention can efficiently carry out photocatalytic overall water splitting hydrogen production and oxygen evolution reactions under xenon lamp illumination. The present invention has the characteristics of simple process, low cost and scalable production, providing a new device-based solution for the industrialization of photocatalytic hydrogen production.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a photocatalytic overall water splitting membrane based on electrospinning, characterized in that, It includes the following steps: S1. Using a carbon nitride precursor as a raw material, ultrathin g-C3N4 nanosheets are obtained through secondary calcination; The Co@BCN obtained by boron doping and cobalt complexing of the g-C3N4 and the acidified Pt@CN obtained by platinum loading and acidification treatment of the g-C3N4 are subjected to electrostatic self-assembly to obtain a Co@BCN / Pt@CN photocatalyst; S2. The Co@BCN / Pt@CN photocatalyst is placed in an organic solvent, ultrasonicated, and then PAN is added, and ultrasonicated continuously to obtain an electrospinning solution. Through electrospinning technology, a photocatalytic overall water splitting film is obtained.

2. The preparation method of the photocatalytic overall water splitting film based on electrospinning according to claim 1, wherein In step S1, the carbon nitride precursor is dicyandiamide; The program of the secondary calcination is: first, heat up to 550 °C at a rate of 5 °C / min and calcine for 4 h, and then heat up to 590 °C at the same rate and calcine for 4 h.

3. The preparation method of the electrospinning-based photocatalytic overall water splitting membrane according to claim 1, wherein, In step S1, the boron doping and cobalt complexing specifically include the following steps: The g-C3N4 and NaBH4 are fully ground and mixed, calcined in an inert gas atmosphere, and the obtained product is washed, ultrasonically stirred and centrifuged multiple times with ethanol and deionized water in sequence, and dried to obtain BCN; The BCN is placed in a cobalt nitrate hexahydrate solution, ultrasonicated, and then ammonia monohydrate is added, and ultrasonicated continuously, filtered and dried to obtain the Co@BCN.

4. The preparation method of the photocatalytic overall water splitting membrane based on electrospinning according to claim 3, characterized in that, The mass ratio of the g-C3N4 to the NaBH4 is 1:4; The program of the calcination is: heat up to 400 °C at a rate of 5 °C / min and calcine for 1 h; The concentration of the cobalt nitrate hexahydrate solution is 0.015 - 0.025 M, and the mass-volume ratio of the BCN, the cobalt nitrate hexahydrate solution to the ammonia monohydrate is 0.05 g:800 μL:0.5 mL.

5. The preparation method of the electrospinning-based photocatalytic overall water splitting membrane according to claim 1, characterized in that, In step S1, the platinum loading and acidification treatment specifically include the following steps: The g-C3N4, a sacrificial agent and chloroplatinic acid are added to water using a water photolysis system, and a reduction reaction is carried out under simulated visible light irradiation. The product is collected and dried to obtain Pt@CN; The Pt@CN is placed in a mixed solution of hydrochloric acid and deionized water, ultrasonicated, statically stirred, filtered and dried to obtain acidified Pt@CN.

6. The preparation method of the electrospinning-based photocatalytic overall water splitting membrane according to claim 5, characterized in that, The sacrificial agent is methanol; The dosage of the chloroplatinic acid accounts for 1 - 3% of the mass of the g-C3N4 in terms of the platinum loading amount; The conditions of the reduction reaction are: irradiate under a xenon lamp with a condensing water of 10 °C, a lamp current of 15 A and a wavelength of 420 - 800 nm for 2 h; The mass-volume ratio of the Pt@CN, the hydrochloric acid to the deionized water is 0.05 g:30 mL:170 mL.

7. The preparation method of the electrospinning-based photocatalytic overall water splitting membrane according to claim 1, wherein In step S1, the electrostatic self-assembly specifically includes the following steps: The acidified Pt@CN is placed in deionized water, ultrasonicated, and then the Co@BCN is added, and ultrasonicated continuously, statically stirred, and the solvent is removed by rotary evaporation and dried to obtain the Co@BCN / Pt@CN photocatalyst.

8. The preparation method of the electrospinning-based photocatalytic overall water splitting membrane according to claim 7, characterized in that, The mass ratio of the Co@BCN to the acidified Pt@CN is 1:

1.

9. The preparation method of the electrospinning-based photocatalytic overall water splitting membrane according to claim 1, characterized in that In step S2, the mass-volume ratio of the Co@BCN / Pt@CN, the organic solvent to the PAN is 0.05 - 0.2 g:5 mL:0.24 g; The time of the ultrasonic wave is 5 h for all cases; The parameters of the electrospinning are as follows: the spinning voltage is 20 kV, the rotating speed of the roller is 50 r / min, the feeding flow rate of the solution is 1 mL / h, and the distance between the spinneret and the roller is 20 cm.

10. Application of the electrospinning-based photocatalytic overall water splitting membrane prepared by the preparation method according to any one of claims 1-9 in photocatalytic overall water splitting for hydrogen production and oxygen production.

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