Method for improving hydrogen evolution reaction activity of ruthenium-based electrocatalyst

Abstract

The invention belongs to the technical field of water electrolysis hydrogen production, and discloses a method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst, ruthenium is loaded on the surface of a nitrogen-doped carbon material by adopting a reduction method, a small amount of water wetting material is introduced, and then heat treatment is performed, so that the mass activity is improved to more than three times. Compared with a ruthenium-based electrocatalyst directly subjected to heat treatment, the ruthenium-based electrocatalyst obtained by adding water for wetting and then performing heat treatment has lower overpotential under the same current density, and the overpotential amplification is less than 10mV in a 24-hour stability test. The method provided by the invention is high in universality, low in cost and simple and convenient to operate, and a new thought is provided for improving the electro-catalysis hydrogen evolution reaction activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by electrolyzing water, and particularly relates to a method for improving the hydrogen evolution reaction (HER) activity of ruthenium-based electrocatalysts. Background Art

[0002] Hydrogen has the characteristics of zero emissions, high energy density, and rich application scenarios. It is one of the most promising fuels to replace traditional petroleum fuels in the future. Hydrogen production by electrolyzing water has the advantages of high production efficiency, environmental friendliness, and high purity of hydrogen, making it an ideal choice for hydrogen production technology. Commercial platinum / carbon (Pt / C) has always been used as a benchmark catalyst for HER due to its excellent catalytic activity in a relatively wide pH range, but its large-scale application is limited by its scarcity and high cost. The price of Ru is less than half of that of Pt, and Ru has a moderate metal-hydrogen bond energy (M-H). The Ru-H bond energy is close to the Pt-H bond energy, with similar hydrogen adsorption ability. Ruthenium-based catalysts have broad application prospects.

[0003] Ruthenium-based electrocatalysts usually adopt means such as structure regulation, support regulation, element doping, alloying, and interface regulation to improve their electrocatalytic activity. No matter which means is adopted, the catalyst needs to go through a heat treatment step, and the presence of water is often ignored during the heat treatment process. For example, Patent CN 114108004 A uses an impregnation method to introduce Ru and other transition metals into the pores of ZIF-8-derived carbon, and then calcines at 300 °C for 1 h. Alloying Ru with other transition metals controls the growth of metal grains during thermal reduction through the confinement effect of ZIF-8-derived carbon, improving the atomic utilization rate and thus enhancing the catalytic activity. However, its process is complex and the cost is high. For example, Patent CN 112680741 A uses an element doping method to form a mesoporous nanostructured RuCo-MOF catalyst through ion etching, and then obtains Ru-CoP hollow porous nanocubes by calcining at 350 °C for 2 h through a phosphating reaction. The doping of phosphorus atoms changes the electronic structure of the material, thereby enhancing the catalytic activity. However, the phosphating process is difficult to control and it is difficult to achieve large-scale production. For example, Patent CN 116791131 A uses a support regulation method to load ruthenium on a diatomite-amorphous cobalt oxide support, and then prepares a ruthenium catalyst supported by a mineral composite material by calcining at 250 °C for 3 h. This mineral composite material improves the electronegativity of ruthenium and has a faster charge transfer rate, thus enhancing the catalytic activity. However, the introduction of metal oxides will cause the catalyst to deactivate in a complex seawater environment.

[0004] In the methods for improving the HER activity of ruthenium-based electrocatalysts described above, the ruthenium-based electrocatalyst materials are in a dry state during heat treatment. The present invention provides a simple method. After adding a small amount of water to wet the heat-treated catalyst, it has a lower charge transfer resistance and faster interfacial reaction kinetics, which can provide a new idea for optimizing the HER activity of the material. Summary of the Invention

[0005] The purpose of the present invention is to provide a simple method for improving the HER activity of ruthenium-based electrocatalysts. This method has strong universality, low cost, and simple operation, and can provide a new idea for enhancing the HER activity.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned invention purpose is as follows: Select a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier, add a small amount of water to wet the ruthenium-based electrocatalyst, and then perform heat treatment to improve the HER activity of the ruthenium-based electrocatalyst.

[0007] According to the above scheme, the ruthenium-based electrocatalyst uses a nitrogen-doped carbon material as the carrier, and the carrier can be selected from nitrogen-doped carbon materials such as nitrogen-doped graphene and nitrogen-doped carbon nanotubes.

[0008] According to the above scheme, the preparation method of the ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier mainly includes the following steps:

[0009] (1) Disperse the nanocarbon material in concentrated acid and ultrasonicate for 5 - 20 min, then add potassium permanganate and stir for 2 - 6 h for oxidation. After washing, obtain the oxidized nanocarbon material;

[0010] (2) Disperse the oxidized nanocarbon material in solvent water, add a nitrogen source, and perform hydrothermal reduction reaction to achieve nitrogen doping. After washing, obtain the nitrogen-doped nanocarbon material;

[0011] (3) Disperse the nitrogen-doped nanocarbon material in solvent water, sequentially dropwise add ruthenium trichloride solution and sodium borohydride aqueous solution and heat for reduction and loading. After washing and drying, obtain a ruthenium catalyst supported on nitrogen-doped carbon material, that is, a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier.

[0012] According to the above scheme, in step (1), the nanocarbon material is one or more of nanographite powder, natural graphite, or carbon nanotubes, etc. Preferably, the sheet diameter of the nanographite powder is 3 - 6 μm, the size of the natural graphite powder is less than 20 μm, and the size of the carbon nanotubes is 10 - 30 μm.

[0013] According to the above scheme, in step (1), the concentrated acid is one of perchloric acid, chlorosulfonic acid, phosphoric acid, etc. The concentration of perchloric acid is 65% - 80%, the concentration of chlorosulfonic acid is above 95%, and the concentration of phosphoric acid is 80% - 95%. When the addition amount of the nanocarbon material is 0.05 - 1.0 g, the addition amount of the concentrated acid is 10 - 100 mL, and the mass ratio of the nanocarbon material to potassium permanganate is between 1:1 and 1:6, and the stirring reaction is carried out for 2 - 6 h.

[0014] According to the above scheme, in step (2), the nitrogen source is one or more of urea, cystine, ammonia water, etc. The concentration of ammonia water is 25% - 28%. The temperature of the hydrothermal reduction reaction is 100 - 200 °C, and the time is 12 - 24 h. The dispersion concentration of the oxidized nanocarbon material in the solvent water is 0.1 - 5 g / L. The mass ratio of urea to the oxidized nanocarbon material is between 1:2 and 1:6, the mass ratio of cystine to the oxidized nanocarbon material is between 1:0.8 and 1:3, and the volume-mass ratio of ammonia water to the oxidized nanocarbon material is between 1 mL:(10 - 20) mg.

[0015] According to the above scheme, in step (3), the dispersion concentration of the nitrogen-doped nanocarbon material in the solvent water is 0.1 - 5 g / L. The mass ratio of the mass of ruthenium atoms put in to the mass of the nitrogen-doped carbon material is 0.05 - 0.2:1. The mass ratio of sodium borohydride to the nitrogen-doped carbon material is 1:4 - 1:12.

[0016] According to the above scheme, in step (3), heating is carried out by oil bath. Add ruthenium trichloride solution, heat up to 60 - 70 °C in an oil bath environment, then add sodium borohydride solution, and then heat up to 100 - 150 °C, and stir and react for 6 - 12 h.

[0017] According to the above scheme, in step (3), the drying temperature is between 40 - 80 °C, and the time is between 6 - 12 h. Preferably, the drying is carried out by vacuum drying treatment, the temperature is between 50 - 60 °C, and the time is between 8 - 10 h.

[0018] According to the above scheme, the ratio of the mass of water used for wetting to the volume of the ruthenium-based electrocatalyst is 1 mL:(50 - 150) mg, preferably 1 mL:(75 - 125) mg, and most preferably 1 mL:100 mg.

[0019] According to the above scheme, the heat treatment temperature is between 100 - 200 °C, and the heat treatment time is between 1 - 6 h. Preferably, the heat treatment temperature is between 160 - 180 °C, and the heat treatment time is between 2 - 3 h.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] First, the method for improving the HER activity of the ruthenium-based electrocatalyst provided by the present invention is simple to operate, low in cost, and highly universal. It can reduce the internal resistance of electron transfer of the catalyst, and the HER activity can be greatly improved.

[0022] Second, the ruthenium-based electrocatalyst supported by nitrogen-doped carbon material is selected in the present invention. By adding a small amount of water to wet the ruthenium-based electrocatalyst and then performing heat treatment, the HER activity of the ruthenium-based electrocatalyst can be improved. The presence of water during the heat treatment process will regulate the surface properties of the ruthenium-based electrocatalyst, promote the destruction of the interfacial water hydrogen bond network on the catalyst surface during the electrolysis of water, and reduce the activation energy of the H–OH bond breaking in the hydrogen atom adsorption (Volmer) step, thereby improving the hydrogen production performance of the catalyst. At the same time, due to the introduction of nitrogen atoms, a stronger interaction can be formed with Ru atoms, enhancing the stability of the material.

[0023] Third, the ruthenium-based electrocatalyst with improved activity by the method of the present invention also has excellent catalytic activity and stability in an alkaline simulated seawater (containing 3.5% NaCl in 1M KOH) environment, and has great potential in future large-scale seawater hydrogen production applications. Brief Description of the Drawings

[0024] Figure 1 It is the electrochemical hydrogen evolution polarization curve of Example 1, Comparative Example 1, and Comparative Example 6 in a 1M KOH environment;

[0025] Figure 2 It is the electrochemical hydrogen evolution polarization curve of Example 1, Comparative Example 1, and Comparative Example 6 in a 1M KOH (containing 3.5% NaCl) environment;

[0026] Figure 3 It is the chronopotentiometry curve of Example 1 and Comparative Example 6 in a 1M KOH environment with a current set to 10 mA / cm 2 ;

[0027] Figure 4 It is the chronopotentiometry curve of Example 1 and Comparative Example 6 in a 1M KOH (containing 3.5% NaCl) environment with a current set to 10 mA / cm 2 ;

[0028] Figure 5 It is the scanning electron microscope image of the ruthenium-based electrocatalyst prepared in Example 1. Detailed Embodiments

[0029] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with examples, but the present invention is not limited to the following examples only.

[0030] In the following examples, the sheet diameter of the nano-graphite powder is 3 - 6 μm, the size of the natural graphite powder is less than 20 μm, and the size of the carbon nanotubes is 10 - 30 μm.

[0031] Example 1

[0032] A method for simply improving the HER activity of ruthenium-based electrocatalysts, the specific steps are as follows:

[0033] (1) Prepare a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier

[0034] Add 0.2 g of nano-graphite powder to 30 mL of perchloric acid with a concentration of 72%, ultrasonicate for 5 min, then add 1.2 g of potassium permanganate, stir and react for 5 h, wash with dilute hydrochloric acid and deionized water respectively, and centrifuge and wash at 9000 r / min for 10 min, repeat three times, and at this time, graphene oxide is obtained;

[0035] Disperse the graphene oxide in solvent water to make a concentration of 1 g / L; take 70 mL of this graphene oxide dispersion, add 5 mL of ammonia water with a concentration of 25%, and carry out a hydrothermal reduction reaction at 180 °C for 24 h, filter and wash to obtain nitrogen-doped graphene;

[0036] Disperse the nitrogen-doped graphene in solvent water to make a concentration of 1 g / L; then take 10 mL of this nitrogen-doped graphene dispersion, add 5 mL of a ruthenium trichloride solution with a concentration of 0.5 g / L (containing approximately 1 mg of ruthenium element, and the mass ratio of ruthenium element to nitrogen-doped graphene is 0.1:1), after heating to 60 °C in an oil bath environment, add 5 mL of a sodium borohydride solution with a concentration of 0.36 g / L, then heat up to 120 °C, stir and react for 8 h, wash, and vacuum dry at 60 °C for 8 h to obtain a ruthenium catalyst supported on nitrogen-doped graphene.

[0037] (2) Modify to enhance the HER activity of the ruthenium-based electrocatalyst: Take 50 mg of the ruthenium catalyst supported on nitrogen-doped graphene solid in a crucible (without a lid), add 0.5 mL of deionized water, and then place it in an oven and heat at 180 °C for 2 h to obtain a ruthenium catalyst supported on nitrogen-doped graphene with improved HER activity, marked as 10% Ru-NRGO (heated with water).

[0038] Comparative Example 1

[0039] The difference between Comparative Example 1 and Example 1 is that: in step (2), 0.5 mL of deionized water is omitted, and 50 mg of the ruthenium catalyst supported on nitrogen-doped graphene solid is directly taken in a crucible, and then placed in an oven and heated at 180 °C for 2 h. Marked as 10% Ru-NRGO (directly heated).

[0040] Example 2

[0041] A simple method for improving the HER activity of ruthenium-based electrocatalysts, the specific steps are as follows:

[0042] (1) Prepare a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier

[0043] Add 0.2 g of nano-graphite powder to 30 mL of perchloric acid with a concentration of 72%, ultrasonicate for 5 min, then add 1.2 g of potassium permanganate, stir and react for 5 h, wash with dilute hydrochloric acid and deionized water respectively, and centrifuge and wash at 9000 r / min for 10 min, repeat three times, and at this time, graphene oxide is obtained;

[0044] Disperse the graphene oxide in solvent water to make a concentration of 1 g / L; take 70 mL of this graphene oxide dispersion, add 5 mL of ammonia water with a concentration of 25%, and carry out a hydrothermal reduction reaction at 180 °C for 24 h, filter and wash to obtain nitrogen-doped graphene;

[0045] Disperse the nitrogen-doped graphene in solvent water to make a concentration of 1 g / L; then take 10 mL of this nitrogen-doped graphene dispersion, add 5 mL of ruthenium trichloride solution with a concentration of 0.25 g / L, after heating to 60 °C in an oil bath environment, add 5 mL of sodium borohydride solution with a concentration of 0.18 g / L, then heat to 120 °C, stir and react for 8 h, wash, and vacuum dry at 60 °C for 8 h to obtain a ruthenium catalyst supported on nitrogen-doped graphene.

[0046] (2) Modify and enhance the HER activity of the ruthenium-based electrocatalyst: Take 50 mg of the ruthenium catalyst supported on nitrogen-doped graphene solid in a crucible, add 0.5 mL of deionized water, and then place it in an oven and heat at 180 °C for 2 h to obtain a ruthenium catalyst supported on nitrogen-doped graphene with improved HER activity, labeled as 5% Ru-NRGO (heated with water).

[0047] Comparative Example 2

[0048] The difference between Comparative Example 2 and Example 2 is that: in step (2), 0.5 mL of deionized water is omitted, directly take 50 mg of the ruthenium catalyst supported on carbon nanotubes solid in a crucible, and then place it in an oven and heat at 180 °C for 2 h, labeled as 5% Ru-NRGO (directly heated).

[0049] Example 3

[0050] A simple method for improving the HER activity of ruthenium-based electrocatalysts, the specific steps are as follows:

[0051] (1) Prepare a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier

[0052] Add 0.4 g of natural graphite powder to 50 mL of phosphoric acid with a concentration of 90%, ultrasonicate for 10 min, then add 1.6 g of potassium permanganate thereto, stir and react for 5 h, wash with dilute hydrochloric acid and deionized water respectively, centrifuge and wash at 9000 r / min for 10 min, repeat three times, and graphene oxide is obtained at this time;

[0053] Disperse the graphene oxide in solvent water to make a concentration of 1 g / L; take 70 mL of the graphene oxide dispersion, add 0.07 g of cystine, carry out hydrothermal reaction at 160 °C for 12 h, filter and wash to obtain nitrogen-doped graphene;

[0054] Disperse the nitrogen-doped graphene in solvent water to make a concentration of 1 g / L; then take 10 mL of the nitrogen-doped graphene dispersion, add 5 mL of ruthenium trichloride solution with a concentration of 0.5 g / L, after heating to 65 °C in an oil bath environment, add 5 mL of sodium borohydride solution with a concentration of 0.36 g / L, then heat to 130 °C, stir and react for 10 h, wash, and vacuum dry at 60 °C for 8 h to obtain a ruthenium-loaded nitrogen-doped graphene catalyst.

[0055] (2) Modify and improve the HER activity of the ruthenium-based electrocatalyst: Take 50 mg of the ruthenium-loaded nitrogen-doped graphene catalyst solid in a crucible, add 0.5 mL of deionized water, and then place it in an oven and heat at 180 °C for 2 h to obtain a ruthenium-loaded nitrogen-doped graphene catalyst with improved HER activity.

[0056] Comparative Example 3

[0057] The difference between Comparative Example 3 and Example 3 is that: in step (2), 0.5 mL of deionized water is omitted, and 50 mg of the ruthenium-loaded carbon nanotube catalyst solid is directly taken in a crucible, and then placed in an oven and heated at 180 °C for 2 h.

[0058] Example 4

[0059] A method for simply improving the HER activity of a ruthenium-based electrocatalyst, the specific steps are as follows:

[0060] (1) Prepare a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier

[0061] Add 0.1 g of carbon nanotubes to 20 mL of chlorosulfonic acid with a concentration of 99%, ultrasonicate for 5 min, then add 0.6 g of potassium permanganate thereto, stir and react for 5 h, wash with dilute hydrochloric acid and deionized water respectively, centrifuge and wash at 9000 r / min for 10 min, repeat three times, and oxidized carbon nanotubes are obtained at this time;

[0062] Disperse carbon nanotubes in solvent water to make a concentration of 1 g / L; take 70 mL of this carbon nanotube dispersion, add 0.014 g of urea, and perform a hydrothermal reduction reaction at 180 °C for 20 h. Then, carry out suction filtration and washing to obtain nitrogen-doped carbon nanotubes.

[0063] Disperse the nitrogen-doped carbon nanotubes in solvent water to make a concentration of 1 g / L; then take 10 mL of this nitrogen-doped carbon nanotube dispersion, add 5 mL of a ruthenium trichloride solution with a concentration of 0.5 g / L. After heating to 60 °C in an oil bath environment, add 5 mL of a sodium borohydride solution with a concentration of 0.36 g / L, and then heat up to 130 °C and stir for 10 h. After washing, perform vacuum drying at 60 °C for 8 h to obtain a ruthenium catalyst supported on nitrogen-doped carbon nanotubes.

[0064] (2) Modify and enhance the HER activity of the ruthenium-based electrocatalyst: Take 50 mg of the ruthenium catalyst supported on nitrogen-doped carbon nanotubes in a crucible, add 0.5 mL of deionized water, and then place it in an oven and heat at 180 °C for 2 h to obtain a ruthenium catalyst supported on nitrogen-doped carbon nanotubes with improved HER activity.

[0065] Comparative Example 4

[0066] The difference between Comparative Example 4 and Example 4 is that in step (2), 0.5 mL of deionized water is omitted, and directly take 50 mg of the ruthenium catalyst supported on carbon nanotubes in a crucible, and then place it in an oven and heat at 180 °C for 2 h.

[0067] Example 5

[0068] A method for simply improving the HER activity of a ruthenium-based electrocatalyst, the specific steps are as follows:

[0069] (1) Prepare a ruthenium-based electrocatalyst with a nitrogen-doped carbon material as the carrier

[0070] Add 0.2 g of carbon nanotubes to 30 mL of chlorosulfonic acid with a concentration of 72%, ultrasonicate for 5 min, then add 1.2 g of potassium permanganate and stir for 5 h. Wash with dilute hydrochloric acid and deionized water respectively, and centrifuge and wash at 9000 r / min for 10 min, repeating three times. At this time, carbon nanotubes are obtained.

[0071] Disperse the carbon nanotubes in solvent water to make a concentration of 1 g / L; take 70 mL of this carbon nanotube dispersion, add 0.014 g of urea, and perform a hydrothermal reduction reaction at 180 °C for 20 h. Then, carry out suction filtration and washing to obtain nitrogen-doped carbon nanotubes.

[0072] Disperse nitrogen-doped carbon nanotubes in solvent water to make a concentration of 1 g / L; then take 10 mL of the nitrogen-doped carbon nanotube dispersion, add 5 mL of a ruthenium trichloride solution with a concentration of 0.25 g / L, heat to 60 °C in an oil bath environment, add 5 mL of a sodium borohydride solution with a concentration of 0.18 g / L, then heat to 130 °C, stir and react for 10 h, wash, and vacuum dry at 60 °C for 8 h to obtain a ruthenium-loaded catalyst on nitrogen-doped carbon nanotubes.

[0073] (2) Modify and improve the HER activity of the ruthenium-based electrocatalyst: Take 50 mg of the ruthenium-loaded catalyst solid on nitrogen-doped carbon nanotubes in a crucible, add 0.5 mL of deionized water, and then place it in an oven and heat at 180 °C for 2 h to obtain a ruthenium-loaded catalyst on nitrogen-doped carbon nanotubes with improved HER activity.

[0074] Comparative Example 5

[0075] The difference between Comparative Example 5 and Example 5 is that: in step (2), 0.5 mL of deionized water is omitted, directly take 50 mg of the ruthenium-loaded catalyst solid on carbon nanotubes in a crucible, and then place it in an oven and heat at 180 °C for 2 h.

[0076] Comparative Example 6

[0077] Commercial 20% Pt / C catalyst.

[0078] Application Example

[0079] Take 5 mg of the catalyst powder of Example 1 after being wetted with water and reprocessed, disperse it in a mixture of 950 μL of solvent (a mixed solvent composed of ethanol and water in a volume ratio of 4:1) and 50 μL of 5% Nafion solution to obtain a catalyst dispersion; coat 5 μL of this catalyst dispersion on a glassy carbon electrode and dry it in an oven at 60 °C, repeating twice. Then conduct an electrochemical hydrogen evolution test in 1 M KOH electrolyte. First, test the cyclic voltammetry curve (CV), set the potential to -1.6 V to -0.4 V, the scanning speed at 100 mV / s, and the number of cycles to 40; secondly, conduct a linear sweep voltammetry (LSV) curve test, set the potential to -1.6 V to -0.4 V, the scanning speed at 5 mV / s, and finally conduct a chronoamperometry curve (i-t) with a current set at 10 mA / cm 2 The corresponding current at -2, and the time is 24 h. According to the same settings, conduct an electrochemical hydrogen evolution test in 1 M KOH (containing 3.5% NaCl) electrolyte. Examples 2 - 5 and Comparative Examples 1 - 5 also conduct electrochemical hydrogen evolution tests according to the above process.

[0080] Table 1 shows the overpotentials of Examples and Comparative Examples 1 - 5 in 1 M KOH electrolyte to reach 10 mA / cm 2The overpotential corresponding to the current density and the mass activity at a potential of -100 mV (V vs RHE). Electrochemical mass activity refers to the activity of a unit mass of metal catalyst in catalyzing the HER reaction under specific conditions, which is defined as the current density exhibited by a unit mass of metal catalyst at a specific potential. The calculation formula is Metal Mass Activity = I / m, and the unit is usually A mg -1 Metal or mA μg -1 Metal . By linear voltammetry testing, the relationship between current and voltage is obtained, and then through inductively coupled plasma optical emission spectrometer (ICP-OES) testing, the specific content of noble metals in the catalyst is obtained. Table 1 provides the mass activity of ruthenium metal at an overpotential of 100 mV for the examples and comparative examples.

[0081] Table 1

[0082]

[0083] Table 2 shows the overpotential corresponding to the current density and the mass activity at a potential of -100 mV (V vs RHE) for Examples 1-5 and Comparative Examples 1-5 in a 1 M KOH (containing 3.5% NaCl) electrolyte to reach 10 mA / cm 2 The overpotential corresponding to the current density and the mass activity at a potential of -100 mV (V vs RHE).

[0084] Table 2

[0085]

[0086]

[0087] As can be seen from Tables 1 and 2, the examples that are heat-treated after being wetted with a small amount of water have a lower overpotential than the comparative examples that are directly heat-treated at a current density of 10 mA / cm in 1 M KOH and 1 M KOH (containing 3.5% NaCl) electrolytes, and the mass activity at a potential of -100 mV (V vs RHE) is increased to three to four times that of the comparative examples. Therefore, by adopting the technical solution of the present invention, a ruthenium-based electrocatalyst supported on a nitrogen-doped carbon material is selected, a small amount of water is added to wet the ruthenium-based electrocatalyst, and then heat treatment is carried out, which can effectively improve the HER activity of the ruthenium-based electrocatalyst, and the mass activity can be increased to more than three times. 2

[0088] Figure 1 As Figure 1 shown in Figure 2, for the catalyst modified in Comparative Example 1, at 10 mA / cm in a 1 M KOH environment and a 1 M KOH (containing 3.5% NaCl) environment 2The overpotentials corresponding to the current densities are 86 mV and 77 mV respectively. For the catalyst of Example 1 after being wetted with water and then heat-treated, the corresponding overpotentials are 37 mV and 10 mV. It can be seen that the wetting effect of a small amount of water during the heat treatment can improve the HER activity. For the commercial 20% Pt / C catalyst (i.e., Comparative Example 6), the corresponding overpotentials are 38 mV and 31 mV. It can be seen that the HER activity of this example is better than that of the commercial 20% Pt / C catalyst.

[0089] As Figure 3 , shown in Figure 4, for the catalyst of Example 1 after being wetted with water and then heat-treated and the commercial 20% Pt / C, the chronopotentiometry curves at a current setting of 10 mA / cm 2 in an environment of 1 M KOH and 1 M KOH (containing 3.5% NaCl) are shown. After continuous operation for 24 h, the overpotential of this catalyst increases by no more than 10 mV, and it still has good HER activity, which is comparable to the stability performance of the commercial 20% Pt / C catalyst.

[0090] In addition, the ruthenium-based electrocatalyst prepared by the modification method of this application can not only ensure the repeatability of electrocatalytic activity, but also has simple operation. It can also be applied to other ruthenium-based electrocatalyst systems and has the potential to be applied to the industrial electrolytic water hydrogen production field.

[0091] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several improvements and transformations can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for improving the activity of a ruthenium-based electrocatalyst for hydrogen evolution reaction, characterized in that: A ruthenium-based electrocatalyst with a nitrogen-doped carbon material as a carrier is selected, water is added to wet the ruthenium-based electrocatalyst, and then heat-treated, thereby improving the hydrogen evolution reaction activity of the ruthenium-based electrocatalyst.

2. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: The ratio between the mass of water used for wetting and the volume of the ruthenium-based electrocatalyst is 1 mL; (50-150) mg.

3. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: The heat treatment temperature is between 100 and 200°C, and the heat treatment time is between 1 and 6 hours.

4. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: The ruthenium-based electrocatalyst uses nitrogen-doped carbon materials as carriers, and the carriers include but are not limited to nitrogen-doped graphene and nitrogen-doped carbon nanotubes.

5. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: The method for preparing the ruthenium-based catalyst using the nitrogen-doped carbon material as a carrier mainly comprises the following steps: (1) dispersing the nanocarbon material in concentrated acid, ultrasonically adding potassium permanganate, stirring and reacting for 2 to 6 hours to achieve oxidation, and washing to obtain an oxidized nanocarbon material; (2) dispersing the oxidized nanocarbon material in solvent water, adding a nitrogen source, performing a hydrothermal reduction reaction to achieve nitrogen doping, and washing to obtain a nitrogen-doped nanocarbon material; (3) Dispersing the nitrogen-doped nanocarbon material in solvent water, sequentially adding ruthenium trichloride solution and sodium borohydride aqueous solution and heating to achieve reduction and loading, and after washing and drying, obtaining a nitrogen-doped carbon material-loaded ruthenium electrocatalyst, that is, a ruthenium-based electrocatalyst with the nitrogen-doped carbon material as a carrier.

6. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 5, characterized in that: In step (1), the nano-carbon material is one or more of nano-graphite powder, natural graphite or carbon nanotubes; wherein the flake diameter of the nano-graphite powder is 3 to 6 μm, the size of the natural graphite powder is less than 20 μm, and the size of the carbon nanotube is 10 to 30 μm.

7. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: In step (1), the concentrated acid is one of perchloric acid, chlorosulfonic acid or phosphoric acid, the concentration of perchloric acid is 65% to 80%, the concentration of chlorosulfonic acid is above 95%, and the concentration of phosphoric acid is 80% to 95%; when the amount of the nano-carbon material added is 0.05 to 1.0 g, the amount of the concentrated acid added is 10 to 100 mL, the mass ratio of the nano-carbon material to potassium permanganate is between 1:1 and 1:6, and the reaction is stirred for 2 to 6 hours.

8. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: In step (2), the nitrogen source is one or more of urea, cystine, and ammonia water, and the concentration of ammonia water is 25% to 28%; the temperature of the hydrothermal reduction reaction is 100 to 200° C., and the time is 12 to 24 hours; the dispersed concentration of the oxidized nano-carbon material in the solvent water is 0.1 to 5 g / L; the mass ratio of urea to the oxidized nano-carbon material is between 1:2 and 1:6, and the mass ratio of cystine to the oxidized nano-carbon material is between 1:0.8 and 1:3; the volume mass ratio of ammonia water to the oxidized nano-carbon material is between 1 mL: (10 to 20) mg.

9. A method for improving the hydrogen evolution reaction activity of a ruthenium-based electrocatalyst according to claim 1, characterized in that: In step (3), the dispersion concentration of the nitrogen-doped nanocarbon material in the solvent water is 0.1-5 g / L; the mass ratio of the input ruthenium atoms to the nitrogen-doped carbon material is 0.05-0.2:1, and the mass ratio of the sodium borohydride to the nitrogen-doped carbon material is 1:4-1:

12.

10. The method for improving the activity of a ruthenium-based electrocatalyst for hydrogen evolution reaction according to claim 1, characterized in that: In step (3), heating is carried out in an oil bath, ruthenium trichloride solution is added, the temperature is raised to 60-70° C. in an oil bath environment, and then sodium borohydride solution is added, the temperature is raised to 100-150° C., and the reaction is stirred for 6-12 hours.

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