Metal / semiconductor / polyoxometallate heterojunction micro-nano material, preparation method and application

Abstract

The invention relates to the technical field of composite heterojunction materials, and discloses a metal / semiconductor / polyoxometallate heterojunction micro-nano material, a preparation method and application, the chemical expression of the micro-nano material is A / AxO / Ay (BOz) m (OH) n, and the micro-nano material is of a two-dimensional nanosheet structure. The preparation method comprises the following steps: placing metal A electrodes on two sides of a reaction container, and placing a metal B target material in the center of the reaction container; deionized water is injected into the reaction container and submerges the surface of the metal B target material; carrying out liquid-phase laser corrosion reaction on the metal B target material under the induction of an electric field; and collecting the reacted metal A electrode into a new container, and standing for more than 2 weeks until a two-dimensional nanosheet material is grown on the surface of the metal A electrode, and the two-dimensional nanosheet material is the A / AxO / Ay (BOz) m (OH) n micro-nano material. The method is simple and convenient to operate, and the A / AxO / Ay (BOz) m (OH) n multistage heterojunction nanostructure with excellent water electrolysis performance can be obtained without any complex chemical additive and reaction step.

Description

Technical Field

[0001] The present invention relates to the technical field of composite heterojunction materials, and particularly relates to a metal / semiconductor / polyoxometalate heterojunction micro-nano material, a preparation method thereof, and an application thereof. Background Art

[0002] Electrochemical overall water splitting is a green, environmentally friendly and efficient hydrogen production method, which involves two reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Due to the slow reaction kinetics of OER and HER, electrochemical overall water splitting often requires a potential higher than the theoretical value, resulting in a large amount of energy loss. At present, noble metal materials such as Pt and IrO2 have been proven to be effective electrocatalysts for OER and HER. However, the scarcity and high cost of noble metal materials have hindered their large-scale application.

[0003] Non-noble metal electrocatalytic materials have attracted extensive attention. Given that the performance of single-component catalysts is still unsatisfactory, combining two or more catalytic materials to construct a heterostructure has become an effective strategy to improve the activity of catalysts. It can not only generate electron redistribution at the interface and achieve a synergistic effect by combining different components, but also produce a new interface structure by changing the composition and crystal phase of the structure, realizing an efficient overall water splitting catalytic function. A large number of studies have shown that heterostructure catalysts have competitive electrocatalytic performance for HER and OER.

[0004] Currently, the main construction strategies include methods such as hydrothermal and chemical vapor deposition. These methods have complex reaction processes, usually require multiple steps of reaction, introduce a large number of chemical reaction reagents, and have cumbersome reaction steps. At the same time, they may have problems such as inability to be widely promoted on a large scale and difficulty in obtaining specific structures. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a metal / semiconductor / polyoxometalate heterojunction micro-nano material, a preparation method thereof, and an application thereof.

[0006] On the one hand, the present invention provides a metal / semiconductor / polyoxometalate heterojunction micro-nano material, and the chemical expression of the micro-nano material is A / A x O / A y (BO z ) m (OH) n , the micro-nano material is a two-dimensional nanosheet structure, wherein, A and B represent different metal materials, A x O represents a metal oxide, A y (BO z ) m (OH) n represents a polyoxometalate, and x, y, z, m, and n are the amounts of corresponding elements or ions.

[0007] On the other hand, the present invention also provides a method for preparing a metal / semiconductor / polyoxometalate heterojunction micro-nano material, comprising the following steps:

[0008] Place the metal A electrodes on both sides of the reaction vessel, and place the metal B target in the center of the reaction vessel;

[0009] Inject deionized water into the reaction vessel to submerge the surface of the metal B target;

[0010] Perform a liquid-phase laser ablation reaction on the metal B target under the induction of an electric field;

[0011] Collect the reacted metal A electrodes into a new container and let them stand for more than 2 weeks until a two-dimensional nanosheet material grows on the surface of the metal A electrodes. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material.

[0012] Preferably, the purity of the metal A electrode is 99% - 99.999%, and the purity of the metal B target is 99% - 99.999%.

[0013] Preferably, the deionized water submerges the surface of the metal B target by 2 mm - 15 mm.

[0014] Preferably, the conductivity of the deionized water is 15 MΩ - 30 MΩ.

[0015] Preferably, the parameters of the laser ablation are: wavelength is 355 nm, 532 nm or 1064 nm, frequency is 1 Hz - 10 Hz, and energy is 50 mJ - 850 mJ / pulse.

[0016] Preferably, the reaction time is 30 min - 2 h.

[0017] Preferably, the voltage of the electric field is 5 V - 180 V.

[0018] Preferably, the metal A electrode is an electrode sheet or a foam metal.

[0019] On yet another aspect, the present invention also discloses the application of the above-mentioned metal / semiconductor / polyoxometalate heterojunction micro-nano material in an electrocatalyst.

[0020] For the metal / semiconductor / polyoxometalate heterojunction micro-nano material, preparation method and application of the present invention, the advantages are that the method of the present invention is simple and convenient to operate, and a multi-level heterojunction nanostructure with excellent water electrolysis performance can be obtained without any complex chemical additives and reaction steps. Description of the Drawings

[0021] Figure 1 It is the SEM image of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material in Example 1 of the present invention;

[0022] Figure 2 It is the XRD pattern of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material in Example 1 of the present invention;

[0023] Figure 3 It is the electrolytic water performance diagram of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material in Example 1 of the present invention;

[0024] Figure 4 It is the structural diagram of the preparation device of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material in Example 1 of the present invention. Detailed implementation manners

[0025] As Figure 1 shown, a metal / semiconductor / polyoxometalate heterojunction micro-nano material according to the present invention, the chemical expression of the micro-nano material is A / A x O / A y (BO z ) m (OH) n , the micro-nano material is a two-dimensional nanosheet structure, where A and B represent different metal materials, A x O represents a metal oxide, A y (BO z ) m (OH) n represents a polyoxometalate, and x, y, z, m, and n are the amounts of the corresponding elements or ions. The two-dimensional nanosheet structure has unique physical and chemical properties, and these properties enable it to exhibit excellent performance in a variety of electrocatalytic reactions.

[0026] Its main manifestations are as follows:

[0027] 1. High specific surface area and active sites

[0028] The two-dimensional nanosheet structure has an ultra-thin thickness and a large specific surface area, which can provide more active sites, thus significantly improving the efficiency of electrocatalytic reactions. For example, two-dimensional nanosheets of transition metal oxides, sulfides, etc. can effectively enhance the activities of hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) by increasing the number of active sites. In this embodiment, oxides of Mo metal are used, thereby effectively enhancing the activities of hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR).

[0029] 2. Excellent electron transport performance

[0030] The ultrathin structure of two-dimensional nanosheets helps shorten the electron transport path and improve the electron transport efficiency.

[0031] 3. Structural controllability

[0032] The two-dimensional nanosheet structure can be regulated by various methods, including chemical doping, defect engineering, heterostructure construction, etc. These regulation means can optimize the electronic structure and surface properties of the material, thereby improving its catalytic performance.

[0033] 4. Good stability and durability

[0034] The two-dimensional nanosheet structure usually has high chemical stability and mechanical strength, and can maintain good performance in a complex electrochemical environment.

[0035] In summary, due to its high specific surface area, excellent electron transport performance, adjustable structural characteristics, and good stability, the two-dimensional nanosheet structure shows great application potential in the field of electrocatalysts. These characteristics give it significant advantages in various electrocatalytic reactions such as hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and carbon dioxide reduction reaction (CO2RR).

[0036] In this embodiment, the electrode and the target material can be Mo, V, Nb, Ta, W, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Au, Ga, In, Sn, Sb, Pb, Bi, Ga, C, B, Ge, Te, etc., and the corresponding nanomaterials can be Cu / Cu2O / Cu3(MoO4)2(OH)2, Ni / NiO / NiMoO4, etc.

[0037] In the present invention, metal A is taken as Cu and metal B is taken as molybdenum as an example for illustration.

[0038] Example 1

[0039] Please refer to Figure 1 , Figure 2 and Figure 4 , this embodiment discloses a preparation method of a metal / semiconductor / polyoxometalate heterojunction micro-nano material, including the following steps:

[0040] S1: Place copper electrode sheets with a purity of 99.99% on both sides of the reaction vessel, and place a molybdenum target with a purity of 99.99% in the center of the reaction vessel. The higher the purity, the lower the impurities contained in the prepared micro-nano material, and the higher the stability of the micro-nano material.

[0041] S2: Inject high-purity deionized water with a conductivity of 18 MΩ into the reaction vessel and submerge the surface of the molybdenum target by 2 mm;

[0042] S3: Turn on the laser and the DC reactive power supply, and carry out a liquid-phase laser ablation reaction on the molybdenum target for 30 min under the induction of an electric field (voltage 5 V). The parameters of the laser ablation are as follows: wavelength 532 nm, frequency 10 Hz, and energy 600 mJ / pulse;

[0043] S4: Collect the reacted copper electrode sheets into a new container and let them stand for 2 weeks until a green two-dimensional nanosheet material grows on the surface of the copper electrode sheets. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material. No additional chemical reagents need to be added in the whole synthesis method, and no multi-step reactions are required, which is more convenient and environmentally friendly than the existing methods.

[0044] Figure 1 The SEM morphology diagram of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material in this embodiment is shown. Figure 1 The left figure in the middle is the low-magnification SEM morphology diagram of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material, and the right figure is the high-magnification diagram. It can be seen from the left figure that the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material has a two-dimensional nanosheet structure.

[0045] Figure 2 The XRD pattern of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material in this embodiment is shown. It can be seen from the figure that there are 8 peaks in the XRD pattern, and the 8 diffraction peaks are respectively at 21.25°, 25.45°, 33.53°, 43.03°, 50.42°, 74.13°, 36.418°, and 61.344°. Among them, 21.25°, 25.45°, and 33.53° respectively correspond to the (101), (111), and (200) crystal planes of Cu3(MoO4)2(OH)2 (JCPDS No. 04-014-9758), 43.03°, 50.42°, and 74.13° respectively correspond to the (111), (200), and (220) crystal planes of Cu (JCPDS No. 04-0836), and 36.418° and 61.344° respectively correspond to the (111) and (220) crystal planes of CuO (JCPDS No. 05-0667). As can be seen from the above, the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material is prepared in this embodiment.

[0046] Example 2

[0047] This embodiment discloses a preparation method of a metal / semiconductor / polyoxometalate heterojunction micro-nano material, including the following steps:

[0048] S1: Place copper electrode sheets with a purity of 99.99% on both sides of the reaction vessel, and place a molybdenum target with a purity of 99.99% in the center of the reaction vessel.

[0049] S2: Inject high-purity deionized water with a conductivity of 15 MΩ into the reaction vessel, and submerge the surface of the molybdenum target by 5 mm;

[0050] S3: Turn on the laser and the DC reaction power supply, and perform a liquid-phase laser ablation reaction on the molybdenum target for 50 min under electric field induction (voltage 150 V). The parameters of the laser ablation are: wavelength 355 nm, frequency 1 Hz, and energy 50 mJ / pulse;

[0051] S4: Collect the reacted copper electrode sheets into a new container, and let them stand for 3 weeks until a green two-dimensional nanosheet material grows on the surface of the copper electrode sheets. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material.

[0052] Example 3

[0053] This example discloses a preparation method of a metal / semiconductor / polyoxometalate heterojunction micro-nano material, including the following steps:

[0054] S1: Place copper foam with a purity of 99.0% on both sides of the reaction vessel, and place a molybdenum target with a purity of 99.0% in the center of the reaction vessel.

[0055] S2: Inject high-purity deionized water with a conductivity of 25 MΩ into the reaction vessel, and submerge the surface of the molybdenum target by 8 mm;

[0056] S3: Turn on the laser and the DC reaction power supply, and perform a liquid-phase laser ablation reaction on the molybdenum target for 1 h under electric field induction (voltage 50 V). The parameters of the laser ablation are: wavelength 355 nm, frequency 5 Hz, and energy 300 mJ / pulse;

[0057] S4: Collect the reacted copper electrode sheets into a new container, and let them stand for 4 weeks until a green two-dimensional nanosheet material grows on the surface of the copper foam. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material.

[0058] Example 4

[0059] This example discloses a preparation method of a metal / semiconductor / polyoxometalate heterojunction micro-nano material, including the following steps:

[0060] S1: Place copper foam with a purity of 99.9% on both sides of the reaction vessel, and place a molybdenum target with a purity of 99.9% in the center of the reaction vessel.

[0061] S2: Inject high-purity deionized water with a conductivity of 20 MΩ into the reaction vessel, and submerge the surface of the molybdenum target by 10 mm.

[0062] S3: Turn on the laser and the DC reaction power supply, and perform a liquid-phase laser ablation reaction on the molybdenum target for 1.2 h under electric field induction (voltage 180 V). The parameters of the laser ablation are: wavelength 532 nm, frequency 6 Hz, and energy 350 mJ / pulse.

[0063] S4: Collect the reacted copper electrode sheets into a new container and let it stand for 4 weeks until green two-dimensional nanosheet materials grow on the surface of the copper foam. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material.

[0064] Example 5

[0065] This example discloses a preparation method of a metal / semiconductor / polyoxometalate heterojunction micro-nano material, including the following steps:

[0066] S1: Place copper foam with a purity of 99.999% on both sides of the reaction vessel, and place a molybdenum target with a purity of 99.999% in the center of the reaction vessel.

[0067] S2: Inject high-purity deionized water with a conductivity of 30 MΩ into the reaction vessel, and submerge the surface of the molybdenum target by 15 mm.

[0068] S3: Turn on the laser and the DC reaction power supply, and perform a liquid-phase laser ablation reaction on the molybdenum target for 1.5 h under electric field induction (voltage 100 V). The parameters of the laser ablation are: wavelength 532 nm, frequency 3 Hz, and energy 400 mJ / pulse.

[0069] S4: Collect the reacted copper electrode sheets into a new container and let it stand for 5 weeks until green two-dimensional nanosheet materials grow on the surface of the copper foam. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material.

[0070] Example 6

[0071] This example discloses a preparation method of a metal / semiconductor / polyoxometalate heterojunction micro-nano material, including the following steps:

[0072] S1: Place copper foam with a purity of 99.999% on both sides of the reaction vessel, and place a molybdenum target with a purity of 99.999% in the center of the reaction vessel.

[0073] S2: Inject high-purity deionized water with a conductivity of 30 MΩ into the reaction vessel, and submerge the surface of the molybdenum target by 15 mm.

[0074] S3: Turn on the laser and the DC reactive power supply, and perform a liquid-phase laser ablation reaction on the molybdenum target for 2 h under electric field induction (voltage 180 V). The parameters of the laser ablation are as follows: wavelength is 1064 nm, frequency is 8 Hz, and energy is 850 mJ / pulse;

[0075] S4: Collect the reacted copper electrode pieces into a new container and let them stand for 6 weeks until green two-dimensional nanosheet materials grow on the surface of the copper foam. This two-dimensional nanosheet material is the Cu / Cu2O / Cu3(MoO4)2(OH)2 micro-nano material.

[0076] Application Example 1

[0077] Application of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material prepared in Example 1 in electrocatalysts.

[0078] Perform electrochemical tests on an electrochemical workstation using a traditional three-electrode system. The reference electrode is silver / silver chloride, the counter electrode is a platinum electrode, the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material is the working electrode, and 1 mol / L sodium sulfate solution is the electrolyte. Using linear sweep voltammetry (LSV), set the scanning range from -0.6 V to 0.02 V, the scanning rate is 10 mV / s, and record the linear sweep voltammogram. The results are as Figure 3 shown. It can be seen from the figure that the hydrogen evolution overpotential of the Cu / Cu2O / Cu3(MoO4)2(OH)2 heterojunction micro-nano material is 110 mV at 10 mA / cm 2 .

[0079] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" are usually based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary explanations, these orientation words do not indicate and imply that the devices or elements referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the protection scope of the present invention.

[0080] For those skilled in the art, according to the technical solutions and concepts described above, various corresponding changes and deformations can be made, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A metal / semiconductor / polyoxometalate heterojunction micro-nano material, characterized in that, The chemical formula of the micro-nano material is A / A x O / A y (BO z ) m (OH) n , the micro-nano material is a two-dimensional nanosheet structure, where A and B represent different metal materials, A x O represents a metal oxide, A y (BO z ) m (OH) n represents a polyoxometalate, and x, y, z, m, n are the amounts of the corresponding elements or ions.

2. A method for preparing a metal / semiconductor / polyoxometalate heterojunction micro-nano material, characterized in that, It includes the following steps: Place metal A electrodes on both sides of the reaction vessel, and place metal B target in the center of the reaction vessel; Inject deionized water into the reaction vessel to submerge the surface of the metal B target; Perform a liquid-phase laser ablation reaction on the metal B target under the induction of an electric field; Collect the reacted metal A electrode into a new container and let it stand for more than 2 weeks until a two-dimensional nanosheet material grows on the surface of the metal A electrode. This two-dimensional nanosheet material is A / A x O / A y (BO z ) m (OH) n micro-nano material.

3. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, characterized in that The purity of the metal A electrode is 99% to 99.999%, and the purity of the metal B target is 99% to 99.999%.

4. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, wherein The deionized water submerges the surface of the metal B target by 2 mm - 15 mm.

5. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, characterized in that The conductivity of the deionized water is 15 MΩ - 30 MΩ.

6. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, characterized in that, The parameters of the laser ablation: the wavelength is 355 nm, 532 nm or 1064 nm, the frequency is 1 Hz - 10 Hz, and the energy is 50 mJ - 850 mJ / pulse.

7. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, characterized in that, The reaction time is 30 min - 2 h.

8. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, characterized in that, The voltage of the electric field is 5 V - 180 V.

9. The preparation method of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 2, characterized in that, The metal A electrode is a metal A electrode sheet or a foam metal.

10. Use of the metal / semiconductor / polyoxometalate heterojunction micro-nano material according to claim 1 in an electrocatalyst.

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