A platinum single-atom hydrogen evolution electrocatalyst and preparation method thereof

Abstract

The present invention provides a method for preparing a platinum single-atom hydrogen evolution electrocatalyst, comprising the following steps: step 1, placing a zinc zeolite imidazole framework in a tubular furnace and performing high-temperature carbonization in a hydrogen-argon mixed gas to obtain a nitrogen-doped carbon nanoframe with a dual structure of micropores and vacancies; step 2, immersing the nitrogen-doped carbon nanoframe in a chloroplatinic acid solution, and performing ultrasonic stirring to obtain a platinum single-atom hydrogen evolution electrocatalyst. The present invention also provides a platinum single-atom hydrogen evolution electrocatalyst, which is prepared by the preparation method of the platinum single-atom hydrogen evolution electrocatalyst.

Description

Technical Field

[0001] The invention belongs to the field of energy and porous materials, and in particular relates to a platinum single-atom hydrogen evolution electrocatalyst and a preparation method thereof. Background Art

[0002] Environmental problems caused by traditional fossil energy consumption are becoming increasingly serious. In order to achieve sustainable development of human society, it is urgent to find efficient, green and pollution-free new energy sources. Hydrogen fuel (H2) is considered to be the main alternative fossil fuel for future energy supply with its cleanest combustion product and highest gravimetric energy density. The hydrogen evolution reaction (HER) by water electrolysis is considered to be an ideal method for producing clean hydrogen. However, the slow kinetics of HER requires a high overpotential to obtain sufficient current density, and the energy conversion efficiency is relatively low. At present, commercial platinum-carbon (Pt / C) catalysts are still considered to be the best catalysts and are widely used in electrochemical HER applications. However, the necessary high Pt loading and the inherent weak binding force between nanoparticles and carriers lead to high catalyst cost and poor stability, which undoubtedly limits the development of water electrolysis hydrogen evolution technology. In recent years, non-precious metal catalysts and precious metal alloy catalysts have emerged one after another, but these catalysts cannot meet the requirements of low price, high activity and high stability at the same time. Summary of the invention

[0003] The present invention is made to solve the above problems, and aims to provide a platinum single atom hydrogen evolution electrocatalyst and a preparation method thereof.

[0004] The present invention provides a method for preparing a platinum single-atom hydrogen evolution electrocatalyst, which has the following characteristics and comprises the following steps:

[0005] Step 1, placing the zinc zeolite imidazole framework in a tube furnace and carbonizing it at high temperature in a hydrogen-argon mixed gas to obtain a nitrogen-doped carbon nanoframework with a dual structure of micropores and vacancies;

[0006] Step 2, immersing the nitrogen-doped carbon nanoframe in a chloroplatinic acid solution, and performing ultrasonic stirring to obtain a platinum single-atom hydrogen evolution electrocatalyst.

[0007] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: wherein step 1 includes the following sub-steps:

[0008] Step 1-1, dissolving dimethylimidazole in a methanol solution by ultrasonication to obtain an imidazole methanol solution;

[0009] Step 1-2, dissolving zinc nitrate hexahydrate in a methanol solution by ultrasonication to obtain a zinc methanol solution;

[0010] Step 1-3, quickly pouring the imidazole methanol solution into the zinc methanol solution to obtain a mixed solution;

[0011] Step 1-4, stirring the mixed solution at room temperature for 24 hours, and then centrifuging and vacuum drying to obtain the zinc zeolite imidazole framework.

[0012] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: the molar ratio of zinc nitrate hexahydrate to dimethylimidazole is 1:4-1:5, the concentration of the imidazole methanol solution is 10%-25%, and the concentration of the zinc methanol solution is 2%-6%.

[0013] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: wherein, in step 1, the concentration of the hydrogen-argon mixed gas is 5% to 10%.

[0014] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: wherein, in step 1, the high-temperature carbonization temperature is 800°C to 1100°C, the time is 2h to 4h, and the heating rate is 5°C / min.

[0015] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: wherein, in step 2, during ultrasonic stirring, the temperature of the chloroplatinic acid solution is controlled to be 50° C. to 70° C., and the reaction time is 12 h to 16 h.

[0016] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: wherein, in step 2, the concentration of the chloroplatinic acid solution is 1 mg / mL.

[0017] The method for preparing the platinum single-atom hydrogen evolution electrocatalyst provided by the present invention may also have the following characteristics: wherein the metal platinum loading of the platinum single-atom hydrogen evolution electrocatalyst is 1.79%.

[0018] The present invention also provides a platinum single-atom hydrogen evolution electrocatalyst, which has the following characteristics: it is prepared by using a preparation method of a platinum single-atom hydrogen evolution electrocatalyst.

[0019] Functions and Effects of the Invention

[0020] According to the preparation method of a platinum single-atom hydrogen evolution electrocatalyst involved in the present invention, the production process is simple, and the zinc zeolite imidazole framework is carbonized at high temperature in a hydrogen-argon mixed atmosphere to obtain a nitrogen-doped carbon nanoframe with both micropores and vacancy structures, and then the framework is used as a carrier and mixed with a chloroplatinic acid solution. During the reaction, the metal ions in the solution are adsorbed through the micropores in the nanoframe, and spatial confinement is performed to inhibit agglomeration, and the vacancies in the nanoframe reduce the adsorbed metal ions in situ, and finally the corresponding platinum single-atom hydrogen evolution electrocatalyst is obtained. And the prepared platinum single-atom hydrogen evolution electrocatalyst has excellent performance, not only high activity, excellent stability, but also the platinum loading of the platinum single-atom hydrogen evolution electrocatalyst is less than one-tenth of the current commercial platinum-carbon catalyst, with extremely high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a transmission electron microscope image of a platinum single-atom hydrogen evolution electrocatalyst in an embodiment of the present invention;

[0022] Figure 2 is a spherical aberration corrected high-resolution transmission electron microscopy image of a platinum single-atom hydrogen evolution electrocatalyst in an embodiment of the present invention;

[0023] Figure 3 is a linear sweep voltammetric graph of hydrogen evolution of a platinum single-atom hydrogen evolution electrocatalyst in a 1M KOH electrolyte in an embodiment of the present invention;

[0024] Figure 4 is a bar graph comparing the mass activity of hydrogen evolution of the platinum single-atom hydrogen evolution electrocatalyst and the commercial platinum-carbon catalyst in the embodiment of the present invention;

[0025] Figure 5 It is a stability test curve diagram of the platinum single-atom hydrogen evolution electrocatalyst in the embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical means and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments and drawings.

[0027] <Example>

[0028] A method for preparing a platinum single-atom hydrogen evolution electrocatalyst of this embodiment comprises the following steps:

[0029] Step 1: placing the zinc zeolite imidazole framework in a tubular furnace and carbonizing it at high temperature in a hydrogen-argon mixed gas to obtain a nitrogen-doped carbon nanoframework having a dual structure of micropores and vacancies.

[0030] Step 1 includes the following sub-steps:

[0031] Step 1-1, dissolving dimethylimidazole in a methanol solution by ultrasonication to obtain an imidazole methanol solution;

[0032] Step 1-2, dissolving zinc nitrate hexahydrate in a methanol solution by ultrasonication to obtain a zinc methanol solution;

[0033] Step 1-3, quickly pouring the imidazole methanol solution into the zinc methanol solution to obtain a mixed solution;

[0034] Step 1-4, stirring the mixed solution at room temperature for 24 hours, and then centrifuging and vacuum drying to obtain the zinc zeolite imidazole framework.

[0035] The molar ratio of zinc nitrate hexahydrate to dimethyl imidazole is 1:4-1:5, the concentration of imidazole methanol solution is 10%-25%, and the concentration of zinc methanol solution is 2%-6%.

[0036] In step 1, the concentration of the hydrogen-argon mixed gas is 5% to 10%.

[0037] In step 1, the high temperature carbonization temperature is 800°C to 1100°C, the time is 2h to 4h, and the heating rate is 5°C / min.

[0038] Step 2, immersing the nitrogen-doped carbon nanoframe in a chloroplatinic acid solution, and performing ultrasonic stirring to obtain a platinum single-atom hydrogen evolution electrocatalyst.

[0039] In step 2, during ultrasonic stirring, the temperature of the chloroplatinic acid solution is controlled to be 50° C. to 70° C., and the reaction time is 12 h to 16 h.

[0040] The concentration of the chloroplatinic acid solution was 1 mg / mL.

[0041] A platinum single-atom hydrogen evolution electrocatalyst in this embodiment is prepared by a preparation method of a platinum single-atom hydrogen evolution electrocatalyst.

[0042] The metal platinum loading of the platinum single atom hydrogen evolution electrocatalyst is 1.79%.

[0043] Figure 1 It is a transmission electron microscope image of the platinum single-atom hydrogen evolution electrocatalyst in the embodiment of the present invention.

[0044] like Figure 1 As shown, the platinum single atom hydrogen evolution electrocatalyst of this embodiment is a rhombic dodecahedron with a relatively uniform size and a diameter of about 1 μm. A thin nitrogen-doped carbon layer can be seen at the edge of the nanoframe, and no obvious metal particles are found.

[0045] Figure 2 This is a spherical aberration corrected high-resolution transmission electron microscopy image of a platinum single-atom hydrogen evolution electrocatalyst in an embodiment of the present invention.

[0046] like Figure 2As shown, the platinum single-atom hydrogen evolution electrocatalyst of this embodiment can be observed as monodispersed platinum atoms under a spherical aberration corrected high-resolution transmission electron microscope, wherein the dark area represents the nitrogen-doped carbon support and the dispersed bright spots are the loaded platinum atoms.

[0047] In this embodiment, the platinum single-atom hydrogen evolution electrocatalyst is ground into powder and prepared into ink of a certain concentration. A small amount of the ink is dropped on the surface of the glassy carbon electrode. After the ink is naturally air-dried, the glassy carbon electrode coated with the ink, the mercury oxide electrode, the graphite rod, and the electrolytic cell filled with the electrolyte are assembled into a three-electrode water electrolysis test system, and the electrocatalytic performance of the system is tested using an electrochemical workstation.

[0048] Figure 3 It is a linear sweep voltammogram of hydrogen evolution of a platinum single-atom hydrogen evolution electrocatalyst in a 1M KOH electrolyte in an embodiment of the present invention.

[0049] like Figure 3 As shown in the figure, in 1M KOH electrolyte, when the catalyst of the water electrolysis test system is a platinum single-atom hydrogen evolution electrocatalyst, only a low overpotential of 24mV is required to make the current density of the reaction system reach 10mA / cm 2 , which is better than commercial platinum-carbon catalysts. At the same time, as the current density increases, the gap between the two catalysts becomes larger and larger, and the advantages of platinum single-atom hydrogen evolution electrocatalysts become more and more obvious.

[0050] Figure 4 It is a bar chart comparing the hydrogen evolution mass activities of the platinum single-atom hydrogen evolution electrocatalyst in the embodiment of the present invention and the commercial platinum-carbon catalyst.

[0051] like Figure 4 As shown, when the overpotential is 50 mV, the mass activity of the platinum single-atom hydrogen evolution electrocatalyst of this embodiment is about 21 times that of the commercial platinum-carbon catalyst, indicating that the platinum single-atom hydrogen evolution electrocatalyst has extremely high economic benefits.

[0052] Figure 5 It is a stability test curve diagram of the platinum single-atom hydrogen evolution electrocatalyst in the embodiment of the present invention.

[0053] like Figure 5 As shown, at 10mA / cm -2 Under the current density, the platinum single-atom hydrogen evolution electrocatalyst of this embodiment can ensure that the catalytic activity is almost unchanged within 24 hours, indicating that the platinum single-atom hydrogen evolution electrocatalyst has excellent practical use potential.

[0054] Functions and Effects of the Embodiments

[0055] According to the preparation method of a platinum single-atom hydrogen evolution electrocatalyst involved in the present embodiment, the production process is simple, and a nitrogen-doped carbon nanoframe with both micropores and vacancy structures is obtained by high-temperature carbonization of a zinc zeolite imidazole framework in a hydrogen-argon mixed atmosphere, and then the framework is used as a carrier and mixed with a chloroplatinic acid solution. During the reaction, the metal ions in the solution are adsorbed through the micropores in the nanoframe, and spatial confinement is performed to inhibit agglomeration, and the vacancies in the nanoframe reduce the adsorbed metal ions in situ, and finally the corresponding platinum single-atom hydrogen evolution electrocatalyst is obtained. And the prepared platinum single-atom hydrogen evolution electrocatalyst has superior performance, not only high activity, excellent stability, but also the platinum loading of the platinum single-atom hydrogen evolution electrocatalyst is less than one-tenth of the current commercial platinum-carbon catalyst, with extremely high economic benefits.

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

Claims

1. A method for preparing a platinum single-atom hydrogen evolution electrocatalyst, characterized in that: The following steps are involved: Step 1, placing the zinc zeolite imidazole framework in a tube furnace and carbonizing it at high temperature in a hydrogen-argon mixed gas to obtain a nitrogen-doped carbon nanoframework with a dual structure of micropores and vacancies; Step 2, immersing the nitrogen-doped carbon nanoframe in a chloroplatinic acid solution, and performing ultrasonic stirring to obtain a platinum single-atom hydrogen evolution electrocatalyst, Wherein, step 1 includes the following sub-steps: Step 1-1, dissolving dimethylimidazole in a methanol solution by ultrasonication to obtain an imidazole methanol solution; Step 1-2, dissolving zinc nitrate hexahydrate in a methanol solution by ultrasonication to obtain a zinc methanol solution; Step 1-3, quickly pouring the imidazole methanol solution into the zinc methanol solution to obtain a mixed solution; Step 1-4, stirring the mixed solution at room temperature for 24 hours, and then centrifuging and vacuum drying to obtain the zinc zeolite imidazole framework, The molar ratio of the zinc nitrate hexahydrate to the dimethylimidazole is 1:4-1:5, the concentration of the imidazole methanol solution is 10%-25%, and the concentration of the zinc methanol solution is 2%-6%. In step 1, the concentration of the hydrogen-argon mixed gas is 5% to 10%, the temperature of the high-temperature carbonization is 1100°C, the time is 2h to 4h, and the heating rate is 5°C / min. In step 2, during the ultrasonic stirring, the temperature of the chloroplatinic acid solution is controlled to be 50° C. to 70° C., and the reaction time is 12 h to 16 h. The metal platinum loading amount of the platinum single-atom hydrogen evolution electrocatalyst is 1.79%.

2. The method for preparing a platinum single-atom hydrogen evolution electrocatalyst according to claim 1, characterized in that: in, In step 2, the concentration of the chloroplatinic acid solution is 1 mg / mL.

3. A platinum single-atom hydrogen evolution electrocatalyst, characterized in that: The catalyst is prepared by the method for preparing the platinum single-atom hydrogen evolution electrocatalyst according to claim 1 or 2.

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