Preparation method of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets

Abstract

This invention provides a method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets, comprising the following steps: Step S1, mixing cobalt salt, niobium salt, and a precipitant, followed by water bath heating reaction; after the reaction, naturally cooling to room temperature, centrifuging to collect the product, washing and drying to obtain the niobium-doped cobalt hydroxide nanosheet composite material; Step S2, uniformly dispersing the niobium-doped cobalt hydroxide nanosheet composite material in pure water, adding platinum source solution, surfactant, and anhydrous ethanol, mixing evenly to obtain a mixed solution, transferring the mixed solution to a reaction vessel for solvothermal reaction; after the reaction, naturally cooling to room temperature, centrifuging to collect the product, washing and drying to obtain the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material. This invention also provides the application of the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material as a HER electrocatalyst.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation methods and electrocatalysis cross-application, specifically relating to a method for preparing a composite material of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets. Background Technology

[0002] In recent years, renewable energy has received increasing attention as an alternative to fossil fuels, and hydrogen, with its high energy density and eco-friendliness, is considered an ideal energy carrier for achieving sustainable economic development. Water electrolysis is a feasible method for producing hydrogen in large quantities with high purity. However, the overpotential at the cathode requires a large amount of additional electrical energy during the water electrolysis hydrogen production process, limiting the practical application of hydrogen evolution reaction (HER). Platinum (Pt), the most commonly used electrocatalyst in the hydrogen evolution reaction, exhibits a very high exchange current density (J0) and a low Tafel slope. However, under alkaline conditions, Pt catalysts are less efficient at hydrogen evolution than under acidic conditions due to their difficulty in breaking down water molecules. Therefore, preparing inexpensive Pt-based HER electrocatalysts with high activity and stability under alkaline conditions remains a challenge.

[0003] To address this issue, a material capable of splitting water molecules needs to be incorporated into the Pt catalyst. Cobalt hydroxide is widely used in this area, as its Co centers exhibit excellent adsorption capacity for water molecules and OH- intermediates, and hydrogen intermediates are strongly adsorbed on Pt, thus significantly promoting the HER kinetics in alkaline solutions. Secondly, niobium, as a 5d transition metal element, can effectively enhance the electrochemical activity of transition metal hydroxides when doped, and bimetallic hydroxides possess a synergistic effect between the two metals. Therefore, loading Pt nanoparticles onto niobium-doped cobalt hydroxide to form a heterostructure can reduce the amount of precious metals used and is expected to improve the catalytic activity and stability of the catalyst for water splitting.

[0004] However, in existing technologies, the preparation methods for doping niobium with hydroxides and combining Pt with transition metal hydroxides are quite complex, and it is difficult to achieve uniform loading of Pt nanoparticles on the hydroxide surface during the preparation process. Therefore, the high preparation cost, poor activity, and poor stability of such catalysts in existing technologies still limit the development and application of electrocatalytic hydrogen production. Summary of the Invention

[0005] This invention is made to solve the above-mentioned problems, and aims to provide a method for preparing a composite material of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets.

[0006] This invention provides a method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets, characterized by the following steps: Step S1, cobalt nitrate hexahydrate, niobium oxalate hydrate, and sodium hydroxide are mixed and heated in a water bath at 80°C for 6-10 hours. The total salt concentration of the cobalt nitrate hexahydrate and the niobium oxalate hydrate is 50 mM, the molar ratio of the cobalt nitrate hexahydrate to the niobium oxalate hydrate is 6:1-15:1, and the amount of sodium hydroxide added is 1-5 times the amount of the inorganic metal salt. After the reaction is completed, the mixture is naturally cooled to room temperature, the product is collected by centrifugation, washed, and dried to obtain the niobium-doped cobalt hydroxide nanosheet composite material.

[0007] Step S2: The niobium-doped cobalt hydroxide nanosheet composite material is uniformly dispersed in pure water, and platinum source solution, surfactant and anhydrous ethanol are added. After mixing evenly, a mixed solution is obtained. The mixed solution is transferred to a reaction vessel for solvothermal reaction. After the reaction is completed, it is naturally cooled to room temperature, the product is collected by centrifugation, and after washing and drying, Pt nanoparticle-supported niobium-doped cobalt hydroxide nanosheet composite material is obtained.

[0008] The method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets provided by the present invention may also have the following feature: wherein, in step S1, the purity of the cobalt nitrate hexahydrate, the niobium oxalate hydrate, and the sodium hydroxide is not lower than that of chemical purity.

[0009] The method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets provided by the present invention may also have the following characteristics: in step S2, the purity of the platinum source solution, the surfactant and the anhydrous ethanol is not lower than chemical purity, the platinum source solution is potassium chloroplatinate solution and the surfactant is sodium linoleate.

[0010] The method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets provided by this invention may also have the following feature: wherein, in step S2, the concentrations of the platinum source solution and the surfactant solution are both 5 × 10⁻⁶. -3 M, wherein the molar ratio of the platinum source solution to the metal inorganic salt is 1.3% to 13.5%, the molar ratio of the platinum source solution to the surfactant is 3:1 to 1:3, and the volume ratio of the anhydrous ethanol to the pure water is 3:1 to 1:3.

[0011] The method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets provided by the present invention may also have the following characteristics: in step S2, the temperature during the solvothermal reaction is 80℃~100℃ and the reaction time is 8h~12h.

[0012] The method for preparing Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets provided by the present invention may also have the following characteristics: in steps S1 and S2, during washing and drying, the nanoparticles are washed with deionized water 3-5 times, washed with anhydrous ethanol 3-5 times, and then placed in a vacuum drying oven for 6-12 hours at a drying temperature of 50°C-80°C.

[0013] The present invention also provides a Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material, characterized in that it is prepared by the above-described method for preparing the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material.

[0014] This invention also provides the application of the above-mentioned Pt nanoparticles supported on niobium-doped cobalt hydroxide nanosheets as a HER electrocatalyst.

[0015] The role and effect of invention

[0016] According to the preparation method of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets of the present invention, niobium-doped cobalt hydroxide nanosheets are first prepared. These niobium-doped cobalt hydroxide nanosheets can adsorb H2O molecules and break them down into adsorbed H+ and OH- ions by gaining electrons. The addition of niobium enhances these effects, which helps to accelerate the adsorption and dissociation of water molecules. Then, small-sized Pt nanoparticles are uniformly loaded onto their surface, which greatly enhances the atom utilization rate. This allows for the adsorption of hydrogen intermediates, optimizes the energy barrier of the intermediates to accelerate catalytic kinetics, and improves the conductivity of the catalyst to accelerate the electron transfer rate. At the same time, the small particle size increases the exposure of active sites, improving the HER activity and cycle stability of the final nanosheet composite material. This makes the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets of the present invention a high-performance electrocatalytic hydrogen evolution material with important application prospects in green energy fields such as water electrolysis for hydrogen production. Meanwhile, this invention prepares a Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material through a simple, green two-step reaction. The process is simple, the preparation conditions are mild, the product has stable morphology and high purity, and the product processing is convenient and simple. In addition, this invention uses simple inorganic salts as reactants, the raw materials are abundant, the industrial cost is low, and it is suitable for medium-scale industrial production. Furthermore, the preparation method of this invention has a certain degree of universality for preparing noble metal-loaded hydroxides and niobium-doped transition metal compounds. Attached Figure Description

[0017] Figure 1 This is an electron microscope image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 1 of the present invention;

[0018] Figure 2This is the energy dispersive X-ray spectrum of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 1 of the present invention;

[0019] Figure 3 This is the X-ray powder diffraction pattern of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 1 of the present invention;

[0020] Figure 4 This is an electron microscope image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 2 of the present invention;

[0021] Figure 5 This is a TEM image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 3 of the present invention;

[0022] Figure 6 The graphs show the HER performance of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composites, Pt / CoOOH, and commercial 20% Pt / C in the test examples of this invention. Detailed Implementation

[0023] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the preparation method of the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material of this invention.

[0024] <Example 1>

[0025] This embodiment describes a method for preparing a composite material of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets, comprising the following steps:

[0026] Step S1, 1.85 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.15 mmol of niobium oxalate hydrate (C 10 H5NbO 20 Niobium-doped cobalt hydroxide nanosheets (Nb-Co(OH)2) were dissolved in 40 mL of deionized water and stirred to obtain a clear and homogeneous mixed solution. Then, 40 mL of 10 mM sodium hydroxide (NaOH) solution was added dropwise, and the mixture was stirred at room temperature for 10 minutes to ensure homogeneity. The mixed solution was placed in an 80 °C water bath and reacted for 8 h to obtain a brown suspension. After cooling to room temperature, the product was collected by centrifugation, washed successively with deionized water and anhydrous ethanol, and then dried in a 60 °C vacuum drying oven for 6 h to obtain niobium-doped cobalt hydroxide nanosheet composite material (Nb-Co(OH)2 material). The material was then sealed and stored for later use.

[0027] In step S2, 2 mL of 5 mM potassium chloroplatinate (K2PtCl6) solution and 2 mL of 5 mM sodium linoleate solution were mixed and stirred for 2 hours to ensure thorough mixing, and this solution was denoted as solution A. 0.04 g of the Nb-Co(OH)2 material prepared in step S1 was dissolved in 20 mL of deionized water and ultrasonically dispersed for 10 minutes. Solution A was then added dropwise, and the mixture was stirred for 20 minutes to ensure thorough mixing. This mixture was then combined with 10 mL of anhydrous ethanol to obtain a mixed solution. This mixed solution was poured into a 50 mL polytetrafluoroethylene high-temperature reactor. The reactor was sealed and placed in an electrically heated constant-temperature drying oven at 2 °C / min. -1 The temperature was increased from room temperature to 90°C and held at 90°C for 10 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, and the precipitate was extracted by centrifugation. The precipitate was then washed successively with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 6 hours to obtain a Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material.

[0028] Figure 1 This is an electron microscope image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 1 of the present invention. Figure 1 In the figure, Figure A is a scanning electron microscope (SEM) image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets at 250 nm magnification; Figures B and C are transmission electron microscope (TEM) images of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets at 20 nm and 10 nm magnification, respectively. The inset in Figure C is a particle size distribution map of Pt nanoparticles.

[0029] like Figure 1 As shown, Figure 1 Figure A, with its low-magnification SEM image, clearly shows that the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets prepared in this embodiment consist of sheet-like structures with a diameter of approximately 100-200 nm, exhibiting no agglomeration and a morphology of a nanosheet array with a lateral dimension of 100-200 nm. Figure 1 The TEM images in Figures B and C show that Pt nanoparticles with a diameter of about 2 nm are uniformly loaded onto the niobium-doped cobalt hydroxide nanosheet composite material. Due to the presence of the layered substrate, the Pt does not agglomerate and is uniform, which makes the Pt nanoparticles loaded onto the niobium-doped cobalt hydroxide nanosheet composite material have a higher atomic utilization rate.

[0030] Figure 2 This is the energy dispersive X-ray spectrum of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 1 of the present invention. Figure 2 In the figure, Figure A is the EDS spectrum and Figure B is the XRD spectrum.

[0031] like Figure 2As shown, the presence of Co, Nb, O and Pt elements can be clearly seen from the EDS spectrum, and the multiple peaks in the XRD spectrum are consistent with the standard peak of Co(OH)2.

[0032] Figure 3 This is the X-ray powder diffraction pattern of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 1 of the present invention. Figure 3 In the figure, Figure A shows the HRTEM image, and Figure B shows the SAED image.

[0033] like Figure 3 As shown, by Figure 3 As shown in Figure A, measurements revealed that the lattice spacing was... Corresponding to the Co(OH)2(101), Co(OH)2(001), and Pt(111) crystal planes respectively, this demonstrates the successful preparation of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite materials. Figure 3 The SAED pattern in Figure B also shows mixed polycrystalline diffraction rings of Co(OH)2(101), Co(OH)2(110), Co(OH)2(100), Pt(220), and Pt(200) crystal planes.

[0034] <Example 2>

[0035] This embodiment describes a method for preparing a composite material of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets, comprising the following steps:

[0036] Step S1, 1.85 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.15 mmol of niobium oxalate hydrate (C 10 H5NbO 20 Niobium-doped cobalt hydroxide nanosheets (Nb-Co(OH)2) were dissolved in 40 mL of deionized water and stirred to obtain a clear and homogeneous mixed solution. Then, 40 mL of 5 mM sodium hydroxide (NaOH) solution was added dropwise, and the mixture was stirred at room temperature for 10 minutes to ensure homogeneity. The mixed solution was placed in an 80°C water bath for 6 hours to react, eventually yielding a brown suspension. After cooling to room temperature, the product was collected by centrifugation, washed successively with deionized water and anhydrous ethanol, and then dried in a 60°C vacuum drying oven for 6 hours to obtain niobium-doped cobalt hydroxide nanosheet composite material (Nb-Co(OH)2 material). This material was then removed, sealed, and stored for later use.

[0037] In step S2, 2 mL of 5 mM potassium chloroplatinate (K2PtCl6) solution and 2 mL of 5 mM sodium linoleate solution were mixed and stirred for 2 hours to ensure thorough mixing, and this solution was denoted as solution A. 0.04 g of the Nb-Co(OH)2 material prepared in step S1 was dissolved in 10 mL of deionized water and ultrasonically dispersed for 10 minutes. Solution A was then added dropwise, and the mixture was stirred for 20 minutes to ensure thorough mixing. This mixture was then further mixed with 10 mL of anhydrous ethanol to obtain a homogeneous solution. This homogeneous solution was poured into a 50 mL polytetrafluoroethylene high-temperature reactor. The reactor was then sealed and placed in an electrically heated constant-temperature drying oven at 2 °C / min. -1 The temperature was increased from room temperature to 100℃ and held at 100℃ for 9 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, and the precipitate was extracted by centrifugation. The precipitate was then washed successively with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60℃ for 6 hours to obtain a Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material.

[0038] Figure 4 This is an electron microscope image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 2 of the present invention. Figure 4 In the figure, Figure A is a SEM image of the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material at a magnification of 500 nm, and Figure B is a TEM image of the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material at a magnification of 10 nm.

[0039] like Figure 4 As shown, the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets prepared in Example 2 still form a layered structure with nanoparticles loaded, and the diameter and thickness remain unchanged.

[0040] <Example 3>

[0041] This embodiment describes a method for preparing a composite material of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets, comprising the following steps:

[0042] Step S1, 1.85 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.15 mmol of niobium oxalate hydrate (C 10 H5NbO 20Niobium-doped cobalt hydroxide nanosheets (Nb-Co(OH)2) were dissolved in 40 mL of deionized water and stirred to obtain a clear and homogeneous mixed solution. Then, 40 mL of 8 mM sodium hydroxide (NaOH) solution was added dropwise, and the mixture was stirred at room temperature for 10 minutes to ensure homogeneity. The mixed solution was placed in an 80 °C water bath and reacted for 8 h to obtain a brown suspension. After cooling to room temperature, the product was collected by centrifugation, washed successively with deionized water and anhydrous ethanol, and then dried in a 60 °C vacuum drying oven for 6 h to obtain niobium-doped cobalt hydroxide nanosheet composite material (Nb-Co(OH)2 material). The material was then sealed and stored for later use.

[0043] In step S2, 2 mL of 5 mM potassium chloroplatinate (K2PtCl6) solution and 0.67 mL of 5 mM sodium linoleate solution were mixed and stirred for 2 hours until fully homogeneous, and this solution was denoted as solution A. 0.04 g of the Nb-Co(OH)2 material prepared in step S1 was dissolved in 15 mL of deionized water and ultrasonically dispersed for 10 minutes. Solution A was then added dropwise, and the mixture was stirred for 20 minutes to ensure thorough mixing. This mixture was then further mixed with 15 mL of anhydrous ethanol to obtain a homogeneous solution. This solution was poured into a 50 mL polytetrafluoroethylene high-temperature reactor. The reactor was sealed and placed in an electrically heated constant-temperature drying oven at 2 °C / min. -1 The temperature was increased from room temperature to 80°C and held at 80°C for 11 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, and the precipitate was extracted by centrifugation. The precipitate was then washed successively with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 6 hours to obtain a Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material.

[0044] Figure 5 This is a TEM image of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composite material in Example 3 of the present invention. Figure 5 In the image, Figures A and B are TEM images of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets at 20 nm and 10 nm magnification.

[0045] like Figure 5 As shown, the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets prepared in Example 3 still form a layered structure with nanoparticles loaded, and the diameter and thickness remain unchanged.

[0046] <Test Example>

[0047] In this test example, the Pt nanoparticles prepared in Example 1 were loaded onto a niobium-doped cobalt hydroxide nanosheet composite material (Pt / Nb-Co(OH)2) and used as a HER catalyst. The HER performance was compared with that of Pt / CoOOH and commercial 20% Pt / C. The nanoparticle-loaded cobalt hydroxide (Pt / CoOOHPt) was prepared by omitting the C content in the raw materials compared to the method in Example 1. 10 H5NbO 20 It is prepared by ·xH2O.

[0048] Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets, Pt / CoOOH, and commercial 20% Pt / C were used as working electrodes, Ag / AgCl (3M KCl solution, ~0.197V vs. NHE) as reference electrodes, and graphite rods as counter electrodes. The electrolyte was 1.0M KOH solution. Electrochemical tests were performed using a CHI 760E electrochemical workstation.

[0049] The preparation process of the working electrode is as follows: Take 5 μL of ultrasonically mixed catalyst dispersion (dispersion composition: 4 mg catalyst material + 20 μL 5 wt% Nafion solution + 750 μL deionized water + 250 mL anhydrous ethanol) and drop it onto an area of ​​0.07 cm². 2 It is placed on a glassy carbon electrode and allowed to air dry naturally before being used as a working electrode.

[0050] Figure 6 The graphs show the HER performance of Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheet composites, Pt / CoOOH, and commercial 20% Pt / C in the test examples of this invention. Figure 6 In Figure A, the linear current-voltage (LSV) curve is shown. The scan rate of the LSV curve is 2 mV / s. -1 Furthermore, all polarization curves were subjected to iR compensation; Figure B shows the Tafel curves, with the Tafel slope calculated by fitting a linear scan curve; Figure C shows the EIS spectra, with the electrochemical impedance spectroscopy (EIS) test frequency range of 0.01-105 Hz and an amplitude of 5 mV; Figure D shows the voltage-time curves for evaluating the electrocatalytic stability of HER for the three materials, at 10 mA cm⁻¹. -2 and 60mA cm -2 The electrochemical HER stability of the catalyst was investigated by performing a chronovoltammetric test for 33 hours.

[0051] like Figure 6 As shown, by Figure 6 As shown in Figure A, the Pt / Nb-Co(OH)2 nanosheet composite material prepared in Example 1 requires only a low overpotential of 199 mV to reach 10 mA cm⁻¹. -2Its current density is 77 mV lower than that of Pt / CoOOH. (From...) Figure 6 As shown in Figure B, which displays the Tafel curves of the materials, the Pt / Nb-Co(OH)₂ nanosheet composite material has a Tafel curve of only 82 mV dec. -1 This is far lower than the 138mV dec of Pt / CoOOH. -1 .Depend on Figure 6 As shown in Figure C, the EIS spectra reveal that the AC impedances of Pt / Nb-Co(OH)₂ and Pt / CoOOH are 35.74 Ω and 88.92 Ω, respectively, indicating that the Pt / Nb-Co(OH)₂ nanosheet composite material possesses strong electron transfer capability and good electrical conductivity. From... Figure 6 As shown in Figure D, after 33 hours of testing, the voltage of Pt / Nb-Co(OH)2 remained almost unchanged, while that of Pt / CoOOH and commercial 20% Pt / C decayed rapidly, indicating that the Pt / Nb-Co(OH)2 nanosheet composite material has good electrocatalytic stability for HER.

[0052] In summary, the Pt nanoparticles supported on niobium-doped cobalt hydroxide nanosheets prepared in this invention exhibit excellent electrochemical hydrogen evolution properties and good cycle stability, making them suitable as high-performance electrocatalytic hydrogen evolution materials for use in green energy fields such as water electrolysis for hydrogen production.

[0053] The role and effect of the embodiments

[0054] As demonstrated in Examples 1-3, the preparation method of the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material of the present invention can successfully prepare the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material through a simple and green two-step reaction. Furthermore, the preparation method of the present invention is simple, the preparation conditions are mild, the product morphology is stable and the purity is high, and the product processing is convenient and simple. In addition, the present invention uses simple inorganic salts as reactants, the raw materials are abundant, the industrial cost is low, and it is suitable for medium-scale industrial production. Moreover, the preparation method of the present invention has a certain degree of universality for the preparation of noble metal-loaded hydroxides and niobium-doped transition metal compounds.

[0055] As can be seen from the test examples, the Pt nanoparticles loaded onto niobium-doped cobalt hydroxide nanosheets prepared in this invention have good HER activity and cycle stability, and can be used as a high-performance electrocatalytic hydrogen evolution material, which has important application prospects in green energy fields such as water electrolysis for hydrogen production.

[0056] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A method for preparing Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composites, characterized in that, The method comprises the following steps: Step S1, mixing cobalt nitrate hexahydrate, niobium oxalate hydrate and sodium hydroxide, and then performing water bath heating reaction at 80 DEG C for 6-10 hours, the total salt concentration of the cobalt nitrate hexahydrate and the niobium oxalate hydrate is 50 mM, the molar ratio of the cobalt nitrate hexahydrate to the niobium oxalate hydrate is 6:1-15:1, and the amount of the sodium hydroxide added is 1-5 times the amount of substance of the metal inorganic salt; after the reaction is completed, the product is collected by centrifugation after natural cooling to room temperature, and then is washed and dried to obtain a niobium-doped cobalt hydroxide nanosheet composite material; Step S2, uniformly dispersing the niobium-doped cobalt hydroxide nanosheet composite material in pure water, adding a platinum source solution, a surfactant and anhydrous ethanol, uniformly mixing to obtain a mixed solution, and then transferring the mixed solution into a reaction kettle to perform a solvothermal reaction; after the reaction is completed, the product is collected by centrifugation after natural cooling to room temperature, and then is washed and dried to obtain a Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material.

2. The method according to claim 1, wherein in step S1, the purity of the cobalt nitrate hexahydrate, the niobium oxalate hydrate and the sodium hydroxide is not less than chemical purity. wherein 3. The method according to claim 1, wherein in step S2, the purity of the platinum source solution, the surfactant and the anhydrous ethanol is not less than chemical purity, the platinum source solution is a potassium chloroplatinate solution, and the surfactant is sodium linoleate.

4. The method according to claim 1, wherein the molar ratio of the platinum source solution to the surfactant is 3:1-1:3, and the volume ratio of the anhydrous ethanol to the pure water is 3:1-1:

3. wherein 5. The method according to claim 1, wherein in step S2, the temperature during the solvothermal reaction is 80-100 DEG C, and the reaction time is 8-12 hours.

6. The method according to claim 1, wherein in steps S1 and S2, during the washing and drying, the product is sequentially washed with deionized water for 3-5 times, washed with anhydrous ethanol for 3-5 times, and then dried in a vacuum drying box for 6-12 hours at a drying temperature of 50-80 DEG C. The Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material is prepared by the method according to any one of claims 1-6. wherein, In step S2, the concentration of the platinum source solution and the surfactant solution is 5x10 -3 M, the molar ratio of the platinum source solution to the metal inorganic salt is 1.3%~13.5%, 8. Use of the Pt nanoparticle-loaded niobium-doped cobalt hydroxide nanosheet composite material according to claim 7 as a HER electrocatalyst. ​ wherein ​ ​ wherein ​ 7. A Pt nanoparticle supported on niobium-doped cobalt hydroxide nanosheet composite, characterized in that, ​ ​

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