Ni (OH) 2 coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Ni (OH) 2 coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst as well as a preparation method and application thereof, and relates to the technical field of catalytic materials. According to the preparation method, in-situ assembly of Ni-MOF by functional groups on an hrGO sheet layer is realized through a solvothermal method, and then self-assembly of Ni (OH) 2 on the surface of the Ni-MOF is induced in situ through chemical etching to form a shell layer, so that the hrGO / Ni-MOF-Ni (OH) 2 core-shell structure is constructed. In the structure, functional groups on the surface of the hrGO not only can anchor metal sites of the MOF and improve the dispersity and stability of the MOF on the surface of the hrGO, but also can be used as an efficient electron acceptor and a transmission channel to effectively inhibit photon-generated carrier recombination and improve the utilization rate of photo-generated electrons; meanwhile, the photo-thermal conversion capacity can be remarkably enhanced through the wide-spectrum response characteristic. A compact heterogeneous interface is formed between Ni-MOF and Ni (OH) 2 generated in situ, the Ni-MOF and hrGO can achieve the photo-thermal synergistic enhancement effect, the interface charge separation and transfer efficiency is further improved, and therefore the photo-thermal catalytic performance of hydrogen production through methanol water phase reforming is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic materials, and in particular to a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst, and a preparation method and application thereof. Background Art

[0002] In recent years, hydrogen, thanks to its significant advantages as a zero-carbon fuel, has seen a surge in demand across numerous key sectors, including transportation, industry, and energy storage. However, hydrogen's inherent characteristics, such as its low density and flammability and explosiveness, pose significant challenges to its long-distance transportation and storage. This not only significantly increases costs but also complicates technical implementation. Therefore, there is an urgent need to develop efficient and safe hydrogen production solutions.

[0003] Among many potential solutions, methanol has shown unique advantages. Methanol is in liquid state at room temperature and pressure, and this characteristic makes it extremely convenient to transport. More importantly, the hydrogen content of methanol is as high as 12.5wt%, which contains rich hydrogen content. In addition, compared with the traditional methane reforming hydrogen production method that requires extreme reaction conditions (800-1000°C), the reaction conditions of methanol liquid phase reforming hydrogen production are milder, and the hydrogen production process can be achieved in a low temperature environment, and energy consumption is significantly reduced. Overall, methanol has become a very ideal hydrogen carrier due to its outstanding performance in transportation convenience, high hydrogen content and low energy consumption hydrogen production.

[0004] Photocatalytic hydrogen production technology utilizes abundant solar energy and water to produce hydrogen, effectively avoiding the high energy consumption and pollution associated with traditional technologies. It is an ideal approach for developing and obtaining hydrogen energy. However, this technology currently faces a key bottleneck: low photocatalytic activity, which hinders efficient solar energy conversion. The root cause of this problem is the severe recombination of photoinduced carriers, sluggish migration kinetics, and poor light utilization efficiency. Long-term research has shown that the synergistic effect of light and heat energy can significantly improve the performance of solar-driven hydrogen production processes. Under illumination, photocatalysts absorb photons and convert them into heat, generating a photothermal effect. This increases the temperature during the reaction, accelerates the movement of reactant molecules, and enhances their interaction with the catalyst's active sites. During the photocatalytic reaction, the photothermal effect facilitates the separation and migration of photogenerated carriers, thereby enhancing catalytic activity. Furthermore, appropriate heat energy can improve the thermal stability of the catalyst, mitigate deactivation, and extend its service life. Therefore, developing photothermal catalysts with excellent photothermal conversion and high photocarrier density is both challenging and important. Summary of the Invention

[0005] The purpose of the present invention is to provide a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst and its preparation method and application, so as to overcome the current problems of low photocatalytic activity, high energy consumption of thermal catalytic methanol liquid phase reforming to produce hydrogen, insufficient catalytic activity of a single catalyst due to a high recombination rate of photogenerated carriers, and poor stability of the catalyst due to photocorrosion and thermal deactivation during the reaction. The photothermal catalyst of the present invention has a core-shell heterostructure, and photogenerated carriers will undergo a directional transfer at the heterojunction interface, effectively suppressing the recombination of electron-hole pairs, extending the life of carriers, and thus improving the activity and catalytic efficiency of the photothermal catalyst. The photothermal catalyst combines photocatalysis and thermal catalysis. The photothermal combined catalysis can partially replace thermal energy with light energy, and use light energy and thermal energy together to provide the heat required for the reaction, lowering the temperature required for the reaction, thereby reducing energy consumption.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: a method for preparing a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst, comprising the following steps:

[0008] hrGO (two-dimensional layered reduced graphene oxide), a nickel source, an organic ligand and an organic solvent are mixed and heated to react to obtain hrGO / Ni-MOF; the hrGO / Ni-MOF and an alkaline solution are mixed and heated and stirred to react to obtain the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst (abbreviated as hrGO / Ni-MOF@Ni(OH)2).

[0009] The present invention first realizes the in-situ assembly of Ni-MOF by functional groups on hrGO sheets through a solvothermal method, and then induces Ni(OH)2 to self-assemble on the Ni-MOF surface to form a shell layer by chemical etching, thereby constructing the hrGO / Ni-MOF@Ni(OH)2 core-shell structure. Specifically, after hrGO, organic ligands and nickel source are dissolved in an organic solvent, during the solvothermal reaction, the functional groups on the hrGO surface anchor nickel ions (Ni 2+ ), the organic ligand molecules will coordinate around the nickel ions in a certain coordination manner, gradually building a multifunctional metal-organic framework to obtain the hrGO / Ni-MOF precursor. When the hrGO / Ni-MOF precursor is mixed with an alkaline solution and heated and stirred for reaction, OH - Attack the protons on some ligands on the surface of Ni-MOF to dissolve some ligands. 2+ -Ligand bond breaks to release free Ni 2+The internal structure of Ni-MOF remains stable, and the nickel nodes (Ni 2+ ) in an alkaline environment with OH - Combined with hydrolysis, Ni(OH)2 is formed. In the structure of this photothermal catalyst, the functional groups on the surface of hrGO can not only anchor the metal sites of MOF, improving the dispersion and stability of MOF on its surface, but also act as efficient electron acceptors and transmission channels to effectively inhibit the recombination of photogenerated carriers and improve the utilization rate of photogenerated electrons; at the same time, its wide spectrum response characteristics can significantly enhance the photothermal conversion capability. A tight heterogeneous interface is formed between Ni-MOF and the in situ generated Ni(OH)2, which can achieve a synergistic photothermal enhancement effect with hrGO, further accelerating the interfacial charge separation and transfer efficiency, thereby significantly improving the photothermal catalytic performance of methanol aqueous phase reforming to produce hydrogen. This catalyst has the advantages of high structural stability, excellent catalytic efficiency and adaptability to low-temperature reactions, and is suitable for a green, efficient and sustainable methanol-hydrogen energy system.

[0010] The Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst obtained by in situ construction of the present invention consists of two parts: an hrGO / Ni-MOF precursor formed by in situ assembly and Ni(OH)2 formed by in situ etching. The Ni(OH)2 serves as a shell layer coating the surface of the Ni-MOF in the hrGO / Ni-MOF.

[0011] Furthermore, the organic ligand includes 2,5-dihydroxyterephthalic acid.

[0012] Furthermore, the nickel source includes one or more of nickel acetate, nickel nitrate and nickel sulfate.

[0013] Furthermore, the organic solvent includes N,N-dimethylformamide (DMF) or ethanol.

[0014] Furthermore, the mass ratio of the hrGO, nickel source and organic ligand is 0.004-0.02:1:0.3-0.4.

[0015] Furthermore, the heating reaction temperature is 120-200° C., and the time is 12-36 hours.

[0016] Furthermore, the alkaline solution includes an aqueous potassium hydroxide solution.

[0017] Furthermore, the mass ratio of the hrGO / Ni-MOF to the alkali contained in the alkali solution is 0.01-0.02:1.

[0018] Furthermore, the temperature of the heating and stirring reaction is 90-100° C., and the time is 1-3 minutes.

[0019] Furthermore, the stirring speed of the heating and stirring reaction is 300 to 500 rpm.

[0020] Optionally, mixing hrGO, the nickel source, the organic ligand and the organic solvent comprises: dispersing hrGO, the nickel source and the organic ligand in the organic solvent, and stirring at 300-500 rpm for 30-60 minutes to obtain a uniform mixed solution.

[0021] Optionally, after the heating reaction is completed, a post-treatment step is further included, and the post-treatment specifically includes cooling, centrifugation and / or filtering, washing, and drying.

[0022] Optionally, mixing the hrGO / Ni-MOF and potassium hydroxide aqueous solution comprises:

[0023] Optionally, after the heating and stirring reaction is completed, a post-treatment step is further included, and the post-treatment specifically includes cooling, centrifugation and / or filtering, washing, and drying.

[0024] Optionally, the drying is performed by vacuum drying at room temperature for 12 to 24 hours.

[0025] The second technical solution of the present invention: a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst prepared according to the above-mentioned preparation method of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst.

[0026] Furthermore, the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst is a cluster spindle structure.

[0027] The third technical solution of the present invention: Application of the above-mentioned Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst in photothermal catalysis (i.e., photothermal synergistic catalysis) of methanol liquid-phase low-temperature reforming to produce hydrogen.

[0028] Furthermore, the application includes: mixing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst with a methanol aqueous solution and a base, and reacting to obtain hydrogen under oxygen-free, light-irradiated and heating conditions.

[0029] Optionally, the base comprises one or more of potassium hydroxide and sodium hydroxide.

[0030] Optionally, the molar ratio of methanol to water in the methanol aqueous solution is 1:1-3.

[0031] Optionally, the usage ratio of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst to the methanol aqueous solution is (4-6) mg:(10-12) mL.

[0032] Optionally, the mass of the base is 5% of the sum of the masses of the methanol and water.

[0033] Optionally, the heating temperature is 90-210°C.

[0034] The present invention discloses the following technical effects:

[0035] (1) The Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst prepared by the present invention has the advantages of adjustable pore structure and surface properties, adjustable active centers, and high structural designability. It can expose more active sites in the methanol liquid-phase reforming hydrogen production reaction to catalyze substrate transport, which is beneficial to the rapid separation and transfer of photogenerated charges.

[0036] (2) In the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst prepared by the present invention, the close heterostructure between Ni(OH)2 and hrGO / Ni-MOF can not only make the catalyst highly stable, but also maximize the collection of solar energy to provide a high surface temperature to accelerate the reaction process.

[0037] (3) The Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst prepared by the present invention combines photocatalysis and thermal catalysis, uses light energy to stimulate electron transitions on the catalyst surface to drive chemical reactions, and uses thermal energy to provide the heat required for the reaction. The two work synergistically to reduce the energy barrier of methanol liquid phase reforming hydrogen production reaction, thereby improving the hydrogen production efficiency. A certain amount of hydrogen can be produced even at low temperatures, meeting the requirements of green, environmentally friendly, energy-saving, and sustainable hydrogen production.

[0038] (4) The present invention obtains Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst through a two-step solvent method. The preparation method is simple, low in cost and energy consumption, and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 XRD patterns of hrGO / Ni-MOF, Ni(OH)2-coated hrRGO / Ni-MOF core-shell heterostructure photothermal catalyst and Ni(OH)2 in Example 1.

[0041] Figure 2These are SEM images of hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Example 1, where (a) is hrGO / Ni-MOF and (b) is Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst.

[0042] Figure 3 These are TEM images of the hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Example 1, where (a) is hrGO / Ni-MOF and (b) is the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst.

[0043] Figure 4 This is a performance comparison chart of the hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts and Ni(OH)2 in Example 1 for photothermal / thermal catalytic methanol liquid-phase low-temperature reforming to produce hydrogen. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0050] When room temperature is mentioned in the specific embodiments of the present invention, it specifically refers to 25±5°C.

[0051] Unless otherwise specified, all raw materials used in the embodiments of the present invention are common commercial products.

[0052] Example 1

[0053] A Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst was prepared by the following steps:

[0054] (1) Preparation of hrGO / Ni-MOF

[0055] 0.02g of hrGO, 0.5g of 2,5-dihydroxyterephthalic acid, and 1.5g of Ni(NO₃)₂·6H₂O were dispersed in 10.5mL of DMF and stirred at 400rpm for 30 minutes to thoroughly mix. The mixed solution was then transferred to a 50mL polytetrafluoroethylene-lined autoclave and heated in a constant-temperature, forced-air drying oven at 150°C for 24 hours. After the reaction, the autoclave was removed and allowed to cool to room temperature. The reaction product was then centrifuged and washed with deionized water until clear. The washed solution was then dried under vacuum at room temperature for 12 hours to obtain hrGO / Ni-MOF.

[0056] (2) In situ construction of Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure catalyst

[0057] 0.2 g of hrGO / Ni-MOF was added to 50 mL of potassium hydroxide aqueous solution (concentration of 6 mol / L), stirred at 400 rpm at 90 °C for 1 min, then cooled to room temperature and centrifuged to obtain the product. The product was washed with deionized water until the washing liquid was clear and dried in vacuum at room temperature for 12 h to obtain a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst.

[0058] Example 2

[0059] The same as Example 1, except that the amount of hrGO used in step (1) is 0.006 g.

[0060] Example 3

[0061] The same as Example 1, except that the amount of hrGO used in step (1) is 0.01 g.

[0062] Example 4

[0063] The same as Example 1, except that the amount of hrGO used in step (1) is 0.03 g.

[0064] Example 5

[0065] The same as Example 1, except that the stirring time at 400 rpm under 90° C. is 2 min.

[0066] Test Example 1

[0067] Characterization Test

[0068] The crystal structure of hRrGO / Ni-MOF, Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst and commercially available Ni(OH)2 in Example 1 was analyzed by X-ray diffractometer. The obtained XRD patterns are shown in the figure below. Figure 1 As shown, hrGO / Ni-MOF, Ni(OH)2 and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts all have good crystallinity, and the characteristic peaks of hrGO and Ni-MOF can be observed in the XRD diffraction pattern of hrGO / Ni-MOF, indicating that hrGO / Ni-MOF has been successfully prepared; the XRD diffraction patterns of hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts are basically consistent, indicating that the Ni-MOF framework in the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst has not collapsed, and there are no obvious defects or changes in the structure. At the same time, the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst also shows the characteristic peak of Ni(OH)2, and the catalyst has been successfully prepared. The XRD patterns of the hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Examples 2 to 5 are basically consistent with those in Example 1.

[0069] The SEM images of the hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Example 1 are shown in Figure 2. Figure 2As shown in Figure 1, (a) shows hrGO / Ni-MOF, and (b) shows a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst. It can be seen that after the in situ construction of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst, the main clustered spindle structure remains unchanged. The SEM images of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Examples 2-5 are essentially consistent with those in Example 1, with clustered spindle structures observed in all cases.

[0070] TEM images of hrGO / Ni-MOF and Ni(OH)2 coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Example 1 are shown in Figure 1. Figure 3 As shown, (a) is hrGO / Ni-MOF, and (b) is a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst. It can be seen that the structure of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst is consistent with that of hrGO / Ni-MOF, indicating that after Ni(OH)2 is coated on the hrGO / Ni-MOF surface, the structure of the hrGO / Ni-MOF crystal can remain stable. The TEM spectra of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst in Examples 2 to 5 are basically consistent with those in Example 1.

[0071] Test Example 2

[0072] The hrGO / Ni-MOF and Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts prepared in each example were used to test the photothermal (or thermocatalytic) low-temperature reforming of methanol into hydrogen. The photothermal (or thermocatalytic) low-temperature reforming of methanol into hydrogen was conducted in a photothermal reactor heated in a furnace equipped with a magnetic stirrer and external lighting. The specific testing method is as follows:

[0073] 0.625 g of KOH was added to a methanol-water solution (methanol: water = 1:1, molar ratio) and ultrasonicated until the KOH dissolved to obtain a mixed solution. In this system, the mass of KOH added was 5% of the total mass of the methanol-water solution. 5 mg of photothermal catalyst was placed in the liner of the photothermal reactor, and 10 mL of the above mixed solution was added. After the reactor was installed, nitrogen was pressurized to 2 MPa and purged three times to ensure complete removal of air. At 210°C and 2 MPa, the photothermal catalytic group reactor was irradiated with a 300 W Xe lamp (CEL-HXF300-T3) for 80 minutes. The thermal catalytic group was not irradiated and reacted directly for 80 minutes. After the reaction, the gas inside the photothermal reactor was collected with an air bag and analyzed by GC (GC9790PLUS) to determine the amount of hydrogen produced.

[0074] Figure 4 The performance comparison diagram of the photothermal / thermal catalytic methanol liquid phase low-temperature reforming hydrogen production of Ni(OH)2, hrGO / Ni-MOF and Ni(OH)2 coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Example 1 is shown. It can be seen that the photothermal catalytic hydrogen production rate of hrGO / Ni-MOF is also improved relative to the thermal catalytic hydrogen production rate (i.e., H2 evolution). The hydrogen production performance of the Ni(OH)2 coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst has been significantly improved under the synergistic effect of light and heat, which is 8.12 times its thermal catalytic hydrogen production rate, nearly 3.8 times that of hrGO / Ni-MOF, and 3.87 times that of Ni(OH)2. This shows that the synergistic effect of photocatalysis and thermal catalysis exhibits superior performance than thermal catalysis alone. The chemical reaction is driven by light energy to excite the electron transition on the catalyst surface, and the heat energy is used to provide the heat required for the reaction. The two work together to reduce the energy barrier of the methanol liquid phase reforming hydrogen production reaction, thereby improving the hydrogen production efficiency. The Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst forms a pn-type band structure at the heterojunction interface, significantly accelerating the directional migration of photogenerated charges while broadening the photoresponse range and promoting the separation of photogenerated charges. The Ni(OH)2 nanoshell is precisely constructed on the surface of hrGO / Ni-MOF. The abundant hydroxyl groups between the Ni(OH)2 layers provide a high density of alkaline sites, promoting the dissociation of the OH and C-H bonds of methanol molecules and significantly improving hydrogen production efficiency.

[0075] The above method was used to change the heating temperature of the reactor, and the photothermal catalytic performance of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst in Example 1 was tested at different temperatures. The results are shown in Table 1.

[0076] Table 1

[0077] Temperature / ℃ <![CDATA[H2evolution(μmol·g cat -1 ·h -1 )]]> 90 359 120 568 150 1279 180 1720 210 261658

[0078] from Figure 1 It can be seen that the photothermal catalyst can also produce a certain amount of hydrogen at low temperature. When the reaction temperature is 90℃, the photothermal catalyst can reach 359μmol·gcat -1 ·h -1 The hydrogen production was measured by the above-mentioned test method. The thermal catalytic performance and photothermal catalytic performance of hrGO / Ni-MOF and Ni(OH)2 in Example 1 at 90°C were tested. It was found that the photothermal and thermal catalytic performance of hrGO / Ni-MOF and Ni(OH)2 in Example 1 no longer produced hydrogen (the hydrogen production was 0).

[0079] The comparison of the photothermal catalytic performance of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalysts in Examples 1 to 5 at 210°C is shown in Table 2. It can be seen that the photothermal catalysts prepared in Examples 1 to 5 can utilize light energy to generate active species in the catalyst and utilize thermal energy to provide the heat required for the reaction. The two work synergistically to improve the efficiency of methanol liquid phase reforming to produce hydrogen.

[0080] Table 2

[0081] Example <![CDATA[H2evolution(μmol·g cat -1 ·h -1 )]]> 1 261658 2 158141 3 197716 4 218879 5 166210

[0082] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst, characterized in that: The following steps are involved: hrGO, a nickel source, an organic ligand and an organic solvent are mixed and heated to react to obtain hrGO / Ni-MOF; the hrGO / Ni-MOF and an alkaline solution are mixed and heated and stirred to react to obtain the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst.

2. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The organic ligand includes 2,5-dihydroxyterephthalic acid.

3. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The nickel source includes one or more of nickel acetate, nickel nitrate and nickel sulfate.

4. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The organic solvent includes N,N-dimethylformamide or ethanol.

5. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The mass ratio of the hrGO, nickel source and organic ligand is 0.004-0.02:1:0.3-0.

4.

6. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The heating reaction temperature is 120-200° C., and the time is 12-36 hours.

7. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The alkaline solution includes an aqueous solution of potassium hydroxide; And / or, the mass ratio of the hrGO / Ni-MOF to the alkali contained in the alkali solution is 0.01-0.02:

1.

8. The method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 1, characterized in that: The temperature of the heating and stirring reaction is 90-100° C., and the time is 1-3 minutes.

9. A Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst prepared by the method for preparing the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to any one of claims 1 to 8.

10. Use of the Ni(OH)2-coated hrGO / Ni-MOF core-shell heterostructure photothermal catalyst according to claim 9 in photothermal catalytic methanol liquid phase low-temperature reforming to produce hydrogen.

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