A method for preparing a bismuth sulfide / bismuth vanadate heterojunction array of a laminated building block structure

Abstract

The application relates to a preparation method of a bismuth sulfide / bismuth vanadate heterojunction array of a laminated building block structure, and belongs to the field of photoelectric semiconductor materials, and particularly relates to a preparation method of a bismuth sulfide / bismuth vanadate heterojunction array. The method aims to solve the problem that the single-component bismuth vanadate prepared by the existing method is not conducive to the transmission of photo-generated carriers and the full utilization of sunlight, and thus results in a low photoelectric current density. The method comprises the following steps: S1, preparing a ZnO seed layer on an FTO conductive substrate; S2, preparing a bismuth vanadate array; S3, calcining; and S4, preparing a bismuth sulfide / bismuth vanadate heterojunction. The bismuth sulfide / bismuth vanadate heterostructure prepared by the in-situ anion exchange growth method is a laminated building block structure, the regular and dense building block structure is formed around the bismuth vanadate nanorod, the bismuth sulfide intersecting nanorods are uniformly stacked around the bismuth vanadate nanorod, the bismuth sulfide / bismuth vanadate heterostructure is conducive to light absorption and the transmission of photo-generated charge carriers, and thus a very high photoelectric current density is obtained. The application is used for preparing a bismuth sulfide / bismuth vanadate heterojunction array.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoelectric semiconductor materials, and particularly relates to a preparation method of a Bi2S3 / BiVO4 heterojunction array. BACKGROUND

[0002] Based on photoelectric semiconductor materials, using solar energy to solve energy crisis and environmental pollution is a hot research topic today. As a classic photoelectric semiconductor material, bismuth vanadate is widely used in the field of photoelectric water splitting to produce hydrogen due to its suitable band gap (about 2.4 eV), liquid phase stability, non-toxicity and low price.

[0003] Single pure-phase bismuth vanadate as a photoanode has obvious defects: (1) as a visible light catalyst, its absorption wavelength does not cover the entire visible light wavelength range, reducing its availability to sunlight; (2) the charge carrier mobility of a single pure-phase bismuth vanadate electrode is low; (3) the charge separation efficiency of a single pure-phase bismuth vanadate is poor. Under this background, a composite electrode based on a bismuth vanadate electrode can change the shortcomings of a single bismuth vanadate electrode. Bi2S3 has an entire visible light absorption, even near-infrared light absorption, due to its narrow band gap (about 1.3 eV), and has extremely high mobility, which makes it show excellent performance in the fields of electronics and optoelectronics. The composite electrode composed of Bi2S3 nanowires and BiVO4 arrays with excellent performance can further improve the performance of the bismuth vanadate photoanode, thereby further improving the conversion efficiency of photoelectric water splitting.

[0004] However, the morphology of the bismuth vanadate prepared by the existing method is mainly nanoparticles or a film composed of nanoparticles. This structure is not conducive to the transmission of photo-generated carriers and the full utilization of sunlight due to the grain boundary potential barrier, resulting in a low photocurrent density. SUMMARY

[0005] The present application aims to solve the problem of the single-component bismuth vanadate prepared by the existing method, which is not conducive to the transmission of photo-generated carriers and the full utilization of sunlight, resulting in a low photocurrent density, and provides a preparation method of a stacked building block structure bismuth sulfide / bismuth vanadate heterojunction array.

[0006] The preparation method of the stacked building block structure bismuth sulfide / bismuth vanadate heterojunction array of the present application comprises the following steps:

[0007] I. Preparing a ZnO seed layer on an FTO conductive substrate

[0008] The ZnO seed solution is uniformly coated on the cleaned FTO glass by using the dip-coating method, and after drying, the FTO substrate covered with a ZnO seed layer is obtained by calcining at 300-450 ℃ for 30-60 min;

[0009] II. Preparation of BiVO4 array

[0010] The sodium metavanadate solution is slowly dripped into the bismuth nitrate solution, and the reaction is carried out for 5-6 min to obtain a reaction solution; the FTO substrate coated with the ZnO seed layer is immersed in the reaction solution with the conductive surface facing downward, and is reacted for 30-150 min under water bath conditions at a reaction temperature of 40-90°C to prepare the tetragonal zircon phase bismuth vanadate nanorod array;

[0011] III. Calcination

[0012] The tetragonal zircon phase bismuth vanadate nanorod array obtained in step II is calcined in a tube furnace with Ar gas at a calcination temperature of 300-400°C for 20-100 min to obtain the BiVO4 precursor with a core-shell structure of tetragonal zircon phase and monoclinic phase;

[0013] IV. Preparation of Bi2S3 / BiVO4 heterojunction

[0014] The Bi2S3 / BiVO4 heterojunction array is obtained by placing the precursor obtained in step III into a solution containing a sulfur compound with the conductive surface facing upward, reacting for 20 min-7 h at a reaction temperature of 80-160°C, and then cooling after the reaction is completed.

[0015] Further, the pulling speed of the dip-coating method in step I is 20-100 mm / min.

[0016] Further, the preparation method of the ZnO seed solution in step I is as follows: zinc acetate anhydrous is placed in an isopropanol solvent, LiOH is added under the condition of keeping at 0°C and constant stirring to prepare a transparent ZnO seed solution; wherein the mass ratio of zinc acetate anhydrous to isopropanol is (0.2-0.4) g:(10-20) mL, and the mass ratio of LiOH to zinc acetate anhydrous is 0.1:1.

[0017] Further, the concentration of the bismuth nitrate solution in step II is 0.001 mol / L, and the concentration of the sodium metavanadate solution is 0.001 mol / L.

[0018] Further, the volume ratio of the sodium metavanadate solution to the bismuth nitrate solution in step II is 1:1.

[0019] Further, in the calcination process of step III, the FTO substrate with the BiVO4 nanorod array is placed obliquely with the conductive surface facing upward, and the included angle with the plane is 45°.

[0020] Further, the flow rate of the Ar gas in step III is 10-20 mL / min.

[0021] Further, the concentration of the solution containing a sulfur compound in step IV is 0.1-2 mol / L.

[0022] Furthermore, in step four, the sulfur-containing compound solution contains thiourea, TAA, or Na2S.

[0023] The preparation principle of this invention:

[0024] The BiVO4 array prepared in this invention is calcined under appropriate temperature control and then reacted with a sulfur-containing compound solution. Without an external Bi source, the S anions in the sulfur-containing compound... 2- It replaced VO4 in bismuth vanadate during the reaction. 2- Bi2S3 nanowires were grown using an in-situ anion exchange method. The tetragonal zircon pure phase bismuth vanadate nanorod array obtained by the water bath method was transformed into a core-shell structure of tetragonal zircon vanadate and monoclinic phase by calcination (this structure is the precursor), thereby preparing a Bi2S3 / BiVO4 heterojunction array with a stacked building block structure.

[0025] Reaction principle: BiVO4 + S 2- =>Bi2S3+VO4 2- S in the sulfur source 2- It replaced part of the VO4 in BiVO4 2- At the location, Bi2S3 is generated.

[0026] The beneficial effects of this invention are:

[0027] 1. The bismuth vanadate prepared by this invention is a nanorod array perpendicular to the substrate, which is a tetragonal zircon phase and has a highly crystalline single crystal structure. This facilitates the rapid extraction of electrons obtained from bismuth sulfide without grain boundary barriers.

[0028] 2. The Bi2S3 / BiVO4 heterojunction prepared by the in-situ anion exchange growth method of this invention has a unique stacked block structure. This regular and dense bismuth sulfide block structure is formed around bismuth vanadate nanorods. The bismuth sulfide nanorods are uniformly stacked around the bismuth vanadate nanorods, with a consistent morphology from top to bottom, which is conducive to light absorption. At the same time, the obtained bismuth sulfide is also a single crystal structure. The shared bismuth atoms are conducive to the transport of photogenerated charge carriers. Therefore, the heterostructure obtains extremely high photocurrent density.

[0029] The method of this invention synthesizes a layered, modular composite photocatalyst, which can effectively promote the separation of photogenerated electrons and holes, increase the light-harvesting ability of the composite photoanode, and improve the carrier migration efficiency, thereby improving the performance of photoelectrocatalytic water splitting. The photocurrent density is 4.4 times that of single pure-phase bismuth vanadate and 5.3 times that of single pure-phase bismuth sulfide.

[0030] 3、The method of the present application does not need to add any auxiliary material for preparing bismuth sulfide, and is a simple substitution reaction. Only the BiVO4 array prepared in step two is placed in a solution containing a sulfur source for reaction, which has the advantages of low loss, low price and simple method.

[0031] 4、The method is simple to operate, and the reaction time and reaction temperature are easy to control. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 TEM image of tetragonal zircon phase BiVO4 prepared for example 1;

[0033] Figure 2 Preparation of Bi2S3 / BiVO4 heterojunction;

[0034] Figure 3 XRD pattern of mixed crystal (monoclinic phase and tetragonal zircon phase) bismuth vanadate after annealing;

[0035] Figure 4 XRD diffraction pattern of Bi2S3 / BiVO4 heterojunction;

[0036] Figure 5 SEM image of Bi2S3 / BiVO4 heterojunction;

[0037] Figure 6 SEM image of Bi2S3 / BiVO4 heterojunction;

[0038] Figure 7 UV-visible absorption spectrum of Bi2S3 / BiVO4 heterojunction;

[0039] Figure 8 Comparison of photocurrent density of Bi2S3 / BiVO4, Bi2S3 and BiVO4;

[0040] Figure 9 Schematic diagram of the placement of FTO substrate with BiVO4 nanorod array during calcination. DETAILED DESCRIPTION

[0041] The technical solution of the present application is not limited to the following specific embodiments, and also includes any combination of the specific embodiments.

[0042] Specific embodiment one: the preparation method of the bismuth sulfide / bismuth vanadate heterojunction array of the stacked building block structure of the present embodiment, comprising the following steps:

[0043] I. Preparation of ZnO seed layer on FTO conductive substrate

[0044] The FTO glass after cleaning is coated with ZnO seed solution uniformly by using dip-coating method, and after drying, the FTO substrate coated with ZnO seed layer is obtained by calcining at 300-450 DEG C for 30-60 min.

[0045] II. Preparation of BiVO4 array

[0046] The sodium metavanadate solution is slowly dropped into the bismuth nitrate solution, and the reaction is carried out for 5-6 min; the solution is colorless and transparent at the beginning, and yellow flocculation appears after the sodium metavanadate solution is added; with the continuous dropping of the sodium metavanadate solution, the yellow flocculation is more and more, and at this time, the solution also becomes bright yellow turbid liquid, which is the reaction liquid; the FTO substrate coated with ZnO seed layer is immersed in the reaction liquid with the conductive surface downward, and the reaction is carried out for 30-150 min under water bath condition at a reaction temperature of 40-90 DEG C, so that the tetragonal zircon phase bismuth vanadate (BiVO4) nanorod array is prepared.

[0047] III. Calcining

[0048] The tetragonal zircon phase bismuth vanadate nanorod array obtained in step II is calcined by using a tube furnace, Ar gas is introduced, the calcining temperature is 300-400 DEG C, and the calcining time is 20-100 min, so that the bismuth vanadate precursor with a core-shell structure of tetragonal zircon phase and monoclinic phase is obtained.

[0049] In the method, low-temperature calcining is adopted in step III, so that the bismuth vanadate with uniform phase can be converted into bismuth vanadate with monoclinic phase, and the bismuth vanadate with monoclinic phase is more easily replaced by S 2- in the reaction, and VO4 2- is more easily replaced.

[0050] IV. Preparation of Bi2S3 / BiVO4 heterojunction

[0051] The precursor obtained in step III is placed in a solution containing a sulfur compound with the conductive surface upward, the reaction time is 20 min-7 h, the reaction temperature is 80-160 DEG C, and after the reaction is completed, cooling is carried out, so that the Bi2S3 / BiVO4 heterojunction array is obtained.

[0052] The Bi2S3 / BiVO4 composite prepared by the method has a very special morphology structure, which is a stacked building block structure, and the building block unit is a bismuth sulfide single crystal, which is beneficial to the transmission of photo-generated electrons, and the bismuth sulfide single crystal and the bismuth vanadate share Bi atoms, which is beneficial to the introduction of electrons into the bismuth vanadate core, and then the electrons are quickly guided out through the bismuth vanadate core with a single crystal phase, so that a very high photocurrent density is obtained.

[0053] The application is to prepare BiVO4 with an array shape, which ensures that the transmission of electrons and holes has a unique direction and the shortest distance, and then prepare Bi2S3 / BiVO4 with a stacked building block structure, the compound conforms to Type II photocatalytic reaction type, and the unique stacked building block structure also ensures that the electrons and holes are not easy to recombine, improves the separation efficiency of the photo-generated charge carriers of the composite photoanode, increases the transmission rate, exhibits higher photocatalytic activity, and also has the advantages of a large specific surface area and provides more active sites.

[0054] Specific embodiment two: different from specific embodiment one, the pulling speed of the dip-pulling method in step one is 20-100 mm / min. The others are the same as specific embodiment one.

[0055] Specific embodiment three: different from specific embodiment one or two, the preparation method of the ZnO seed solution in step one is to place zinc acetate anhydrous in an isopropanol solvent, add LiOH under the condition of keeping at 0 DEG C and continuously stirring, and prepare a transparent ZnO seed solution; wherein the mass ratio of zinc acetate anhydrous to isopropanol is (0.2-0.4) g:(10-20) mL, and the mass ratio of LiOH to zinc acetate anhydrous is 0.1:1. The others are the same as specific embodiment one or two.

[0056] Specific embodiment four: different from any one of specific embodiments one to three, the concentration of the bismuth nitrate solution in step two is 0.001 mol / L, and the concentration of the sodium metavanadate solution is 0.001 mol / L. The others are the same as any one of specific embodiments one to three.

[0057] Specific embodiment five: different from any one of specific embodiments one to four, the volume ratio of the sodium metavanadate solution to the bismuth nitrate solution in step two is 1:1. The others are the same as any one of specific embodiments one to four.

[0058] Specific embodiment six: different from any one of specific embodiments one to five, in the calcination process of step three, the FTO substrate with BiVO4 nanorod array is placed with the conductive surface upward at an angle of 45 DEG with the plane, and the schematic diagram is shown in Figure 9 . The others are the same as any one of specific embodiments one to five.

[0059] The electrode with a certain angle can be in full contact with the bismuth vanadate nanorod during calcination, ensure uniform phase transition of the core-shell structure, and prepare uniform bismuth sulfide structure during subsequent ion replacement, so as to obtain a building block stacked structure. If placed horizontally, the argon gas will contact the side and top when passing through the electrode, which will cause uneven phase transition.

[0060] Specific embodiment seven: different from one of the specific embodiments one to six is that the flow rate of Ar gas in step three is 10-20 mL / min. The others are the same as one of the specific embodiments one to six.

[0061] Low flow rate makes the surface of bismuth vanadate nanorods have little resistance to the flow rate of gas, and the whole film has uniform resistance, so that the surface activation and phase transition process of bismuth vanadate nanorods during calcination can be uniform, especially during the cooling process, the low flow rate has influence on the morphology, phase transition ratio and uniformity of the phase transition bismuth vanadate nanorods.

[0062] Specific embodiment eight: different from one of the specific embodiments one to seven is that the concentration of the sulfur compound solution in step four is 0.1-2 mol / L. The others are the same as one of the specific embodiments one to seven.

[0063] Specific embodiment nine: different from one of the specific embodiments one to eight is that the sulfur compound in the sulfur compound solution in step four is thiourea, TAA or Na2S. The others are the same as one of the specific embodiments one to eight.

[0064] The following embodiments of the application will be described in detail. The following embodiments are implemented on the premise of the technical scheme of the application, and detailed implementation schemes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0065] Embodiment 1:

[0066] The preparation method of the bismuth sulfide / bismuth vanadate heterojunction array of the stacked building block structure in this embodiment includes the following steps:

[0067] I. Preparation of a ZnO seed layer on an FTO conductive substrate

[0068] The ZnO seed solution is uniformly coated on the cleaned FTO glass by dip-coating method, and after drying, the FTO substrate covered with a ZnO seed layer is obtained by calcining at 350℃ for 30 min. The pulling speed of the dip-coating method is 40 mm / min. The preparation method of the ZnO seed solution is as follows: zinc acetate anhydrous is placed in isopropanol solvent, LiOH is added under the condition of keeping at 0℃ and continuously stirring, and transparent ZnO seed solution is prepared. The mass ratio of zinc acetate anhydrous to isopropanol is 0.3g:20mL, and the mass ratio of LiOH to zinc acetate anhydrous is 0.1:1.

[0069] II. Preparation process of BiVO4 array

[0070] 0.4851 g of Bi (NO3) 3 ·5H2O plus 0.3 mL of HNO3 (mass concentration of HNO3 is 68%) and 4.7 mL of deionized water are dissolved to obtain a 0.001 mol / L bismuth nitrate solution; 0.122 g of NaVO3 plus 5 mL of deionized water are dissolved to obtain a 0.001 mol / L sodium metavanadate solution, which is ultrasonically dissolved until the solution is uniform;

[0071] The sodium metavanadate solution is slowly added to the bismuth nitrate solution, and the reaction is carried out for 5 min. The solution is initially colorless and transparent. When the sodium metavanadate solution is added, yellow flocculent substances appear. As the sodium metavanadate solution is continuously added, the yellow flocculent substances become more and more numerous, and at this time the solution also turns into a bright yellow turbid liquid, which is the reaction liquid;

[0072] The FTO substrate coated with the ZnO seed layer is immersed in the reaction liquid with the conductive surface facing downward, and the reaction is carried out in a water bath for 150 min at a reaction temperature of 80°C. After the reaction is completed, the FTO substrate is immediately rinsed with a large amount of deionized water and dried in air to obtain a bismuth vanadate (BiVO4) nanorod array in a tetragonal zirconite phase;

[0073] III. Calcination

[0074] The bismuth vanadate nanorod array in a tetragonal zirconite phase obtained in step II is calcined in a tube furnace with Ar gas being introduced at a flow rate of 16.6 mL / min. The calcination temperature is 350°C, and the calcination time is 60 min to obtain a bismuth vanadate precursor in a tetragonal zirconite phase and a monoclinic phase core-shell structure. During the calcination process, the FTO substrate with the BiVO4 nanorod array is placed with the conductive surface facing upward at an angle of 45° with the plane, as shown in the schematic diagram of Figure 8 .

[0075] The method takes low-temperature calcination in step III, so that the bismuth vanadate in a uniform phase can be converted into bismuth vanadate in a monoclinic phase, which is more easily replaced with S 2- during the reaction. 2- .

[0076] IV. Preparation of a Bi2S3 / BiVO4 heterojunction

[0077] The precursor obtained in step III is placed in a 1 mol / L thiourea solution with the conductive surface facing upward. 5 mL of the reaction kettle is added with 10 mL of the thiourea solution. The reaction time is 4 h, and the reaction temperature is 120°C. After the reaction is completed, rapid cooling to room temperature is carried out by blowing with a fan for 30 min to obtain a Bi2S3 / BiVO4 heterojunction array.

[0078] The Bi2S3 / BiVO4 heterojunction array obtained in this embodiment is subjected to effect verification, as follows:

[0079] Figure 1The image shows a TEM image of the prepared tetragonal zircon phase BiVO4. As can be seen from the image, the obtained BiVO4 has clear diffraction spots arranged in an orderly manner, indicating that it is a single crystal with high crystallinity.

[0080] Figure 2 This is a flowchart illustrating the preparation process of the Bi2S3 / BiVO4 heterojunction. The bismuth vanadate nanorod array prepared in this example is a tetragonal zircon phase, containing VO4... 2- Ions do not readily react with sulfur-containing compounds. 2- Since ion exchange reactions occur, the proportion of monoclinic bismuth vanadate in bismuth vanadate can be controlled from the outside to the inside by controlling the calcination time and temperature. Thus, when preparing Bi2S3 / BiVO4 heterojunction materials using the anion exchange growth method, the proportion of Bi2S3 can be controlled by controlling the reaction time and temperature, resulting in a Bi2S3 / BiVO4 heterojunction array photoanode with a stacked building block structure and high photocurrent density.

[0081] Figure 3 The image shows the XRD pattern of the bismuth vanadate mixed crystals obtained after low-temperature calcination. XRD standard card number 14-0133 represents tetragonal zircon phase bismuth vanadate, and XRD standard card number 14-0688 represents monoclinic phase bismuth vanadate. The formation of the mixed crystals plays an important role in controlling the subsequent growth of bismuth sulfide and can control the conversion ratio of bismuth sulfide in the heterostructure.

[0082] Depend on Figure 4 The XRD diffraction pattern of the Bi2S3 / BiVO4 heterojunction shows that the heterojunction is composed of a ternary mixture of bismuth sulfide, monoclinic bismuth vanadate, and tetragonal zircon bismuth vanadate.

[0083] Depend on Figure 5 and Figure 6 As can be seen from the scanning electron microscope images, the Bi2S3 / BiVO4 heterojunction array with a layered block structure obtained in this embodiment is a regular and dense block structure with a consistent morphology from top to bottom.

[0084] Figure 7 The image shows the UV-Vis absorption spectrum of the Bi2S3 / BiVO4 heterojunction. As can be seen from the UV-Vis absorption spectrum of the Bi2S3 / BiVO4 heterojunction, the loading of bismuth sulfide greatly increases the absorption efficiency of sunlight, with absorption across almost the entire wavelength range, which is beneficial for making full use of sunlight.

[0085] Figure 8For Bi2S3 / BiVO4, Bi2S3 and BiVO4 photocurrent density contrast chart, compared with pure phase bismuth vanadate and pure phase bismuth sulfide, the photocurrent density at 1.23V is 4.4 times and 5.3 times respectively, and this heterostructure material fully plays the advantages of each material, (1) the loaded bismuth sulfide is beneficial to the full utilization and conversion of solar energy, (2) the building block structure stacked by single crystal bismuth sulfide nanorods is beneficial to the smooth introduction of photo-generated electrons into the bismuth vanadate main body, and is beneficial to the separation of photo-generated charge carriers, (3) the high crystallization performance of the main body bismuth vanadate is beneficial to the transmission of photo-generated electrons, (4) the structure perpendicular to the substrate is beneficial to the electron export along the shortest path, so a very high photocurrent density, that is, a very high water splitting activity is obtained.

Claims

1. A method for preparing a stacked building block structure of a bismuth sulfide / bismuth vanadate heterojunction array, characterized by The method comprises the following steps: I. uniformly coating a ZnO seed solution on the FTO glass after cleaning by using a dip-coating method, and calcining at 300-450℃ for 30-60min after drying to obtain an FTO substrate covered with a ZnO seed layer; II. slowly dropping a sodium metavanadate solution into a bismuth nitrate solution, and reacting for 5-6min to obtain a reaction solution; immersing the FTO substrate covered with the ZnO seed layer in the reaction solution with the conductive surface downward, and reacting for 30-150min under water bath conditions at a reaction temperature of 40-90℃ to prepare a tetragonal zirconite phase bismuth vanadate nanorod array; III. calcining the tetragonal zirconite phase bismuth vanadate nanorod array obtained in step II in a tube furnace with Ar gas, at a calcining temperature of 300-400℃ for 20-100min to obtain a tetragonal zirconite phase and monoclinic phase core-shell structure bismuth vanadate precursor; IV. placing the precursor obtained in step III into a solution containing a sulfur compound with the conductive surface upward, reacting for 20min-7h at a reaction temperature of 80-160℃, and cooling after the reaction to obtain a Bi2S3 / BiVO4 heterojunction array; In the calcining process in step III, the FTO substrate with the BiVO4 nanorod array is placed with the conductive surface upward and inclined at an angle of 45° to the plane; and the flow rate of the Ar gas in step III is 10-20mL / min.

2. A method of fabricating a Bi2S3 / BiVO4 heterojunction array of stacked building blocks according to claim 1, characterized in that The pulling speed of the dip-coating method in step I is 20-100mm / min.

3. A method of producing a Bi2S3 / BiVO4 heterojunction array of a stacked building block structure according to claim 1 or 2, characterized in that The preparation method of the ZnO seed solution in step I is as follows: placing zinc acetate anhydrous in an isopropyl alcohol solvent, adding LiOH under 0℃ conditions while continuously stirring to prepare a transparent ZnO seed solution; wherein the mass of the zinc acetate anhydrous to the volume of the isopropyl alcohol is (0.2-0.4)g:(10-20)mL, and the mass ratio of LiOH to zinc acetate anhydrous is 0.1:

1.

4. The method of claim 1, wherein the method further comprises the step of: The concentration of the bismuth nitrate solution in step II is 0.001mol / L, and the concentration of the sodium metavanadate solution is 0.001mol / L. ​ 5. The method of claim 1 or 4, wherein the method is characterized by The volume ratio of the sodium metavanadate solution to the bismuth nitrate solution in step II is 1:

1.

6. A method of fabricating a Bi2S3 / BiVO4 heterojunction array of stacked building blocks according to claim 5, characterized in that The concentration of the solution containing a sulfur compound in step IV is 0.1-2mol / L.

7. A method of fabricating a Bi2S3 / BiVO4 heterojunction array of stacked building blocks according to claim 6, characterized in that The sulfur compound in the solution containing a sulfur compound in step IV is thiourea, TAA or Na2S.

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