A ruthenium dioxide nanoparticle - acidified carbon nanotube composite material, a preparation method thereof and an application thereof

Abstract

The present invention discloses a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material and its preparation method and application. The composition of the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention includes acidified carbon nanotubes, ruthenium dioxide nanoparticles and a carbon layer, and its preparation method includes the following steps: 1) preparing acidified carbon nanotubes; 2) preparing acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles; 3) preparing polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles; 4) calcining the polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles. The ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention has the advantages of high catalytic activity, excellent stability and low cost, and its preparation method is simple to operate, safe and highly controllable, suitable for use as a catalyst for electrocatalytic water decomposition to produce hydrogen, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysis, and in particular to a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen (H2) has high energy density and is a carbon-free, green energy source, making it a promising alternative to fossil fuels. However, current hydrogen production relies heavily on non-renewable fossil fuels such as natural gas and crude oil, generating large amounts of gaseous pollutants during the production process. Therefore, there is an urgent need to develop green, environmentally friendly, and sustainable hydrogen production technologies.

[0003] Electrocatalytic water splitting is a green and environmentally friendly hydrogen production technology with broad application prospects. Among current water electrolysis hydrogen production technologies, alkaline water electrolysis (AWE) and proton exchange membrane water electrolysis (PEMWE) have gradually achieved industrialization. The key to electrocatalytic water splitting hydrogen production technology lies in the catalyst, whose performance directly affects hydrogen production efficiency. Therefore, the development of high-performance catalysts is crucial.

[0004] Ir-based catalysts (e.g., IrO2) are common anode catalysts in industry, with advantages such as good durability and high activity, while Pt / C catalysts are common cathode catalysts in industry. However, since both Ir and Pt are rare precious metal materials, they are not only expensive but also have extremely low abundance on Earth. Therefore, the large-scale application of Ir-based catalysts and Pt / C catalysts is greatly limited.

[0005] Ruthenium (Ru) is much cheaper than Ir and Pt, and its oxides (e.g., RuO2) exhibit superior catalytic performance and have great application prospects. However, the stability of existing Ru-based catalysts is generally poor. Most Ru-based catalysts reported so far have a low stability at about 10 mA / cm 2 At low current densities, Ru-based catalysts lose their activity within tens of hours, far from meeting the requirements for industrial application. Furthermore, existing Ru-based catalysts suffer from low mass activity, making them unable to meet the requirements for high performance and long-term stability at commercial current densities.

[0006] Therefore, it is of great significance to develop a Ru-based catalyst with high catalytic activity, excellent stability and low cost. Summary of the Invention

[0007] The purpose of the present invention is to provide a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material and a preparation method and application thereof.

[0008] The technical solution adopted by the present invention is:

[0009] A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material comprises acidified carbon nanotubes, ruthenium dioxide nanoparticles and a carbon layer; the ruthenium dioxide nanoparticles are anchored on the surface of the acidified carbon nanotubes; and the carbon layer is coated on the surface of the acidified carbon nanotubes and the ruthenium dioxide nanoparticles.

[0010] Preferably, the particle size of the ruthenium dioxide nanoparticles is 2 nm to 5 nm.

[0011] More preferably, the particle size of the ruthenium dioxide nanoparticles is 2.3 nm to 2.6 nm.

[0012] Preferably, the thickness of the carbon layer is 0.6 nm to 1 nm.

[0013] Preferably, the carbon layer is made of polyaniline through calcination.

[0014] A method for preparing the above-mentioned ruthenium dioxide nanoparticle-acidified carbon nanotube composite material comprises the following steps:

[0015] 1) dispersing carbon nanotubes in an acid solution and performing an acidification treatment to obtain acidified carbon nanotubes;

[0016] 2) dispersing the acidified carbon nanotubes and a soluble ruthenium salt in water for a hydrothermal reaction to obtain the acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles;

[0017] 3) dispersing the acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles, aniline, and an initiator in water for reaction to obtain polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles;

[0018] 4) calcining the polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material.

[0019] Preferably, the acid solution in step 1) is a mixed acid made of sulfuric acid and nitric acid.

[0020] Further preferably, the acid solution in step 1) is a mixed acid prepared by mixing 95% to 98% sulfuric acid by mass and 68% to 70% nitric acid by mass in a volume ratio of 2.8 to 3.2:1.

[0021] Preferably, the acidification treatment in step 1) is carried out at 70° C. to 90° C., and the acidification treatment time is 4 h to 6 h.

[0022] Preferably, the soluble ruthenium salt in step 2) is ruthenium trichloride (RuCl3), triruthenium dodecacarbonyl (Ru3(CO) 12 ) at least one of.

[0023] Further preferably, the soluble ruthenium salt in step 2) is ruthenium trichloride.

[0024] Preferably, in step 2), the mass ratio of the acidified carbon nanotubes to the soluble ruthenium salt is 1:0.5-2.

[0025] Preferably, the hydrothermal reaction in step 2) is carried out at 150° C. to 180° C., and the reaction time is 4 h to 6 h.

[0026] Preferably, in step 3), the mass ratio of the acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles to aniline is 1:0.5-2.

[0027] Preferably, the initiator in step 3) is at least one of ammonium persulfate and ferric chloride.

[0028] Further preferably, the initiator in step 3) is ammonium persulfate.

[0029] Preferably, the amount of the initiator in step 3) is 100% to 300% of the mass of aniline.

[0030] Preferably, the reaction in step 3) is carried out at 0°C to 5°C, and the reaction time is 10h to 12h.

[0031] Preferably, the specific operation of the calcination in step 4) is: first control the heating rate to be 2°C / min-5°C / min from room temperature to 350°C-500°C, then keep it at that temperature for 2h-4h, and then control the cooling rate to be 2°C / min-5°C / min to cool it down to room temperature.

[0032] A catalyst for producing hydrogen by electrocatalytically decomposing water comprises the above-mentioned ruthenium dioxide nanoparticle-acidified carbon nanotube composite material.

[0033] The beneficial effects of the present invention are as follows: the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention has the advantages of high catalytic activity, excellent stability, low cost, etc., and its preparation method is simple to operate, safe, and highly controllable. It is suitable for use as a catalyst for electrocatalytic water decomposition to produce hydrogen and has broad application prospects.

[0034] Specifically:

[0035] 1) The ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention comprises a carbon layer made by calcining polyaniline. The carbon layer has good hydrophilicity, which can increase the charge transfer rate during the oxygen evolution reaction (OER), thereby greatly reducing the reaction energy barrier of the OER, and ultimately significantly improving the OER electrocatalytic performance of the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material;

[0036] 2) The ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention contains ruthenium dioxide nanoparticles. The ruthenium dioxide nanoparticles are rich in oxygen defects, which can increase the oxidation state of Ru and promote the p orbital of O to be closer to the Fermi level, thereby enhancing the electronic binding between the ruthenium dioxide nanoparticles and the carbon nanotubes. It has excellent intrinsic activity, so that the mass activity and stability of the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material under acidic, neutral and alkaline OER conditions are far superior to commercial ruthenium dioxide (commercial ruthenium dioxide at a current density of 10 mA / cm 2 The ruthenium dioxide nanoparticle-acidified carbon nanotube composite material exhibits ultra-low overpotential in acidic, neutral, and alkaline hydrogen evolution reaction (HER) processes, with catalytic performance close to that of commercial Pt / C catalysts.

[0037] 3) The production cost of the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention is much lower than that of the Ir-based catalyst and Pt / C catalyst that have been industrially applied;

[0038] 4) The preparation method of the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material of the present invention is simple to operate, safe, and highly controllable, and is suitable for large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 These are the SEM and TEM images of PANI / RuO2 / CNTs and C / RuO2 / CNTs in Example 1.

[0040] Figure 2 These are the XRD patterns of PANI / RuO2 / CNTs and C / RuO2 / CNTs in Example 1.

[0041] Figure 3 This is the dispersion test result diagram of PANI / RuO2 / CNTs and C / RuO2 / CNTs in Example 1.

[0042] Figure 4 This is a graph showing the results of the activity and stability test of the C / RuO2 / CNTs in Example 1 and the commercially available RuO2 / C catalyst (the electrolyte is a H2SO4 solution with a concentration of 0.5 mol / L).

[0043] Figure 5 The results of the activity and stability test of the C / RuO2 / CNTs and commercially available RuO2 / C catalysts in Example 1 (the electrolyte is PBS buffer with a concentration of 1.0 mol / L) are shown.

[0044] Figure 6This is a graph showing the results of the activity and stability test of the C / RuO2 / CNTs in Example 1 and the commercially available RuO2 / C catalyst (the electrolyte is a KOH solution with a concentration of 1.0 mol / L).

[0045] Figure 7 This is the activity test result diagram of RuO2 / CNTs in Comparative Example 1.

[0046] Figure 8 This is the activity test result diagram of RuO2 / CNTs in Comparative Example 2.

[0047] Figure 9 This is the activity test result diagram of C / RuO2 / CNTs in Comparative Example 3. DETAILED DESCRIPTION

[0048] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0049] Example 1:

[0050] A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, the preparation method of which comprises the following steps:

[0051] 1.5 g of carbon nanotubes were stirred and dispersed in 120 mL of an acid solution prepared by mixing 98% sulfuric acid and 68% nitric acid in a volume ratio of 3:1. The solution was then refluxed at 80° C. for 5 h and filtered. The filtered solid was washed with water until neutral and then dried to obtain acidified carbon nanotubes.

[0052] 2) ultrasonically dispersing the acidified carbon nanotubes in water to prepare an acidified carbon nanotube dispersion with a concentration of 10 mg / mL, then mixing 1.5 mL of the acidified carbon nanotube dispersion, 14 mL of ethanol, and 14 mL of water, and then adding 1 mL of a 0.05 mmol / L RuCl3 solution dropwise while stirring. After the addition, stirring was continued for 10 minutes. Then, 100 mg of urea was added and stirring was continued for 20 minutes. The resulting mixed solution was transferred to a polytetrafluoroethylene-lined reactor, and the reactor was placed in an oven at 180°C for 4 hours. After naturally cooling to room temperature, it was centrifuged and the solid obtained by centrifugation was alternately washed with anhydrous ethanol and water, and then dried at 60°C to obtain acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (denoted as RuO2 / CNTs);

[0053] 3) 20 mg of RuO2 / CNTs was added to 20 mL of water and ultrasonicated for 1 h to prepare a RuO2 / CNTs dispersion. 5 mL of 0.5 mol / L hydrochloric acid was placed in an ice bath at 0°C, and 30 μL of aniline was added dropwise while stirring. The RuO2 / CNTs dispersion was then added dropwise, followed by 5 mL of ammonium persulfate hydrochloric acid solution (containing 60 mg of ammonium persulfate, prepared with 0.5 mol / L hydrochloric acid). Stirring was continued for 10 h after the addition, and the mixture was centrifuged. The solid obtained by centrifugation was alternately washed with anhydrous ethanol and water, and then dried at 60°C to obtain polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (denoted as PANI / RuO2 / CNTs).

[0054] 4) 10 mg of PANI / RuO2 / CNTs was loaded into a porcelain boat and placed in a tube furnace. The temperature was first raised from room temperature to 350°C at a heating rate of 3°C / min, then kept at this temperature for 4 h, and then cooled to room temperature at a cooling rate of 3°C / min to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material (denoted as C / RuO2 / CNTs).

[0055] Performance testing:

[0056] 1) The scanning electron microscope (SEM) and transmission electron microscope (TEM) images of PANI / RuO2 / CNTs and C / RuO2 / CNTs in this embodiment are as follows: Figure 1 (a is SEM of PANI / RuO2 / CNTs, b is TEM of PANI / RuO2 / CNTs, c is SEM of C / RuO2 / CNTs, d is TEM of C / RuO2 / CNTs).

[0057] Depend on Figure 1 It can be seen that:

[0058] a) The surface of PANI / RuO2 / CNTs is jagged and consists of acidified carbon nanotubes, ruthenium dioxide nanoparticles anchored on the surface of the acidified carbon nanotubes, and a polyaniline coating layer covering the outside. The particle size of the ruthenium dioxide nanoparticles is about 1.3 nm, and the polyaniline coating layer is relatively thick, with a thickness of about 26.7 nm.

[0059] b) C / RuO2 / CNTs consists of acidified carbon nanotubes, ruthenium dioxide nanoparticles anchored on the surface of the acidified carbon nanotubes, and a carbon layer covering the outside. The particle size of the ruthenium dioxide nanoparticles is about 2.3nm, and the carbon layer is very thin, with a thickness of about 0.6nm.

[0060] 2) The X-ray diffraction (XRD) patterns of PANI / RuO2 / CNTs and C / RuO2 / CNTs in this example are shown in Figure 2. Figure 2 (a is PANI / RuO2 / CNTs, b is C / RuO2 / CNTs) as shown.

[0061] Depend on Figure 2 It can be seen that no obvious RuO2 peak can be observed in PANI / RuO2 / CNTs, while a carbon peak can be observed in C / RuO2 / CNTs.

[0062] 3) 4 mg of PANI / RuO2 / CNTs and C / RuO2 / CNTs in this example were added to 1 mL of water and shaken several times. The dispersion test results were shown in the figure below. Figure 3 (a is C / RuO2 / CNTs, b is PANI / RuO2 / CNTs).

[0063] Depend on Figure 3 Yes: PANI / RuO2 / CNTs has poor dispersibility in water, while C / RuO2 / CNTs has good dispersibility in water, indicating that C / RuO2 / CNTs has good hydrophilicity.

[0064] 4) 5 mg of C / RuO2 / CNTs in this example and commercially available RuO2 / C (Shanghai McLean Biochemical Technology Co., Ltd.) were added to a naphthol solution (containing 10 μL of naphthol, and the solvent was composed of water and isopropanol in a volume ratio of 7:3), and then ultrasonicated for 30 minutes to prepare a catalyst ink. Then 10 μL of the catalyst ink was dropped onto a glassy carbon electrode (disc-shaped) with a diameter of 5 mm and dried naturally at room temperature to obtain a working electrode. The working electrode, the counter electrode (platinum wire) and the reference electrode (Ag / AgCl electrode, 0.197 V vs. RHE) were assembled into a three-electrode cell. The electrolyte was a 0.5 mol / L H2SO4 solution, a 1.0 mol / L PBS buffer solution or a 1.0 mol / L KOH solution. The Shanghai Chenhua workstation (CHI760) was used to test the voltage in the range of 1.1 V vs. RHE to 1.6 V. The catalyst activity and stability were tested under the conditions of RHE (C / RuO2 / CNTs for 2000 CV cycles and commercial RuO2 / C for 200 CV cycles). The test results are as follows: Figure 4 (a is the OER polarization curve, b is the HER polarization curve), Figure 5 (a is the OER polarization curve, b is the HER polarization curve) and Figure 6 (a is the OER polarization curve, b is the HER polarization curve).

[0065] Depend on Figure 4 It can be seen that:

[0066] a) OER polarization curve shows that after 2000 CV cycles, C / RuO2 / CNTs has a high conductivity at a current density of 10 mA / cm 2The OER overpotential hardly increases under low conditions, showing ultra-high stability. However, after 200 CV cycles, the commercial RuO2 / C shows no significant difference at a current density of 10 mA / cm 2 The OER overpotential increases significantly under the current density of 10 mA / cm 2 It exhibits an ultra-low overpotential (172 mV), exceeding most reported catalysts and is one of the best catalysts.

[0067] b) The HER polarization curve shows that after 2000 CV cycles, C / RuO2 / CNTs still maintains an overpotential of 40 mV, indicating that C / RuO2 / CNTs has extremely high stability and is superior to most of the catalysts reported so far.

[0068] Depend on Figure 5 It can be seen that:

[0069] a) OER polarization curve shows that after 2000 CV cycles, C / RuO2 / CNTs has a high conductivity at a current density of 10 mA / cm 2 The OER overpotential hardly increases under low conditions, showing ultra-high stability. However, after 200 CV cycles, the commercial RuO2 / C shows no significant difference at a current density of 10 mA / cm 2 The OER overpotential increases significantly under the current density of 10 mA / cm 2 It exhibits an ultra-low overpotential (195 mV), exceeding most reported catalysts and is one of the best catalysts.

[0070] b) The HER polarization curve shows that after 2000 CV cycles, C / RuO2 / CNTs still maintains an overpotential of 38 mV, indicating that C / RuO2 / CNTs has extremely high stability and is superior to most of the currently reported catalysts.

[0071] Depend on Figure 6 It can be seen that:

[0072] a) OER polarization curve shows that after 2000 CV cycles, C / RuO2 / CNTs has a high conductivity at a current density of 10 mA / cm 2 The OER overpotential hardly increases under low conditions, showing ultra-high stability. However, after 200 CV cycles, the commercial RuO2 / C shows no significant difference at a current density of 10 mA / cm 2 The OER overpotential increases significantly under the current density of 10 mA / cm 2 It exhibits an ultra-low overpotential (195 mV), exceeding most reported catalysts and is one of the best catalysts.

[0073] b) The HER polarization curve shows that after 2000 CV cycles, C / RuO2 / CNTs still maintains an overpotential of 40 mV, indicating that C / RuO2 / CNTs has extremely high stability and is superior to most of the catalysts reported so far.

[0074] In summary, C / RuO2 / CNTs is a catalyst with ultra-high catalytic activity and excellent stability in the acidic OER process over a wide pH range.

[0075] Example 2:

[0076] A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, the preparation method of which comprises the following steps:

[0077] 1) 20 mg of RuO2 / CNTs (same as in Example 1) was added to 10 mL of water and ultrasonicated for 1 h to prepare a RuO2 / CNTs dispersion. 10 mL of 0.5 mol / L hydrochloric acid was then placed in an ice bath at 0°C. 30 μL of aniline was then added dropwise while stirring, followed by the RuO2 / CNTs dispersion. 10 mL of ammonium persulfate hydrochloric acid solution (containing 60 mg of ammonium persulfate prepared with 0.5 mol / L hydrochloric acid) was then added dropwise. Stirring was continued for 10 h after the addition was complete, and the mixture was centrifuged. The solid obtained by centrifugation was alternately washed with anhydrous ethanol and water, and then dried at 60°C to obtain polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (denoted as PANI / RuO2 / CNTs).

[0078] 2) 10 mg of PANI / RuO2 / CNTs was loaded into a porcelain boat and placed in a tube furnace. The temperature was first raised from room temperature to 350°C at a heating rate of 3°C / min, then kept at this temperature for 4 h, and then cooled to room temperature at a cooling rate of 3°C / min to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material (denoted as C / RuO2 / CNTs).

[0079] Performance testing:

[0080] 1) Through SEM and TEM tests, it was found that the microscopic morphology of C / RuO2 / CNTs in this example was highly similar to that of C / RuO2 / CNTs in Example 1, and the particle size of RuO2 nanoparticles and the thickness of the carbon layer were very close.

[0081] 2) The catalyst activity and stability tests (same as in Example 1) showed that the C / RuO2 / CNTs in this example had an OER overpotential of 176 mV, 267 mV, and 199 mV when the electrolyte was a 0.5 mol / L H2SO4 solution, a 1.0 mol / L PBS buffer solution, and a 1.0 mol / L KOH solution, respectively. The HER overpotentials were 60 mV, 41 mV, and 42 mV, respectively, showing ultra-high catalytic activity. After 2000 CV cycles in three different electrolytes, the C / RuO2 / CNTs exhibited a high catalytic activity at a current density of 10 mA / cm 2 The OER and HER overpotentials under these conditions barely increased (<10 mV), demonstrating ultrahigh stability.

[0082] Example 3:

[0083] A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, the preparation method of which comprises the following steps:

[0084] 1) 20 mg of RuO2 / CNTs (same as in Example 1) was added to 20 mL of water and ultrasonicated for 1 h to prepare a RuO2 / CNTs dispersion. 5 mL of 0.5 mol / L hydrochloric acid was placed in an ice bath at 0°C, and 40 μL of aniline was added dropwise while stirring. The RuO2 / CNTs dispersion was then added dropwise, followed by 5 mL of ammonium persulfate hydrochloric acid solution (containing 80 mg of ammonium persulfate, prepared with 0.5 mol / L hydrochloric acid). Stirring was continued for 10 h after the addition, and the mixture was centrifuged. The solid obtained by centrifugation was alternately washed with anhydrous ethanol and water, and then dried at 60°C to obtain polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (denoted as PANI / RuO2 / CNTs).

[0085] 2) 10 mg of PANI / RuO2 / CNTs was loaded into a porcelain boat and placed in a tube furnace. The temperature was first raised from room temperature to 350°C at a heating rate of 3°C / min, then kept at this temperature for 4 h, and then cooled to room temperature at a cooling rate of 3°C / min to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material (denoted as C / RuO2 / CNTs).

[0086] Performance testing:

[0087] 1) Through SEM and TEM tests, it was found that the microscopic morphology of C / RuO2 / CNTs in this example was highly similar to that of C / RuO2 / CNTs in Example 1, and the particle size of RuO2 nanoparticles and the thickness of the carbon layer were very close.

[0088] 2) The catalyst activity and stability tests (same as in Example 1) showed that the C / RuO2 / CNTs in this example had an OER overpotential of 174 mV, 265 mV, and 197 mV when the electrolyte was a 0.5 mol / L H2SO4 solution, a 1.0 mol / L PBS buffer solution, and a 1.0 mol / L KOH solution, respectively. The HER overpotentials were 59 mV, 39 mV, and 41 mV, respectively, showing ultra-high catalytic activity. After 2000 CV cycles in three different electrolytes, the C / RuO2 / CNTs exhibited a high catalytic activity at a current density of 10 mA / cm 2 The OER and HER overpotentials under these conditions barely increased (<10 mV), demonstrating ultrahigh stability.

[0089] Example 4:

[0090] A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, the preparation method of which comprises the following steps:

[0091] 1) 20 mg of RuO2 / CNTs (same as in Example 1) was added to 20 mL of water and ultrasonicated for 1 h to prepare a RuO2 / CNTs dispersion. 5 mL of 0.5 mol / L hydrochloric acid was placed in an ice bath at 0°C, and 30 μL of aniline was added dropwise while stirring. The RuO2 / CNTs dispersion was then added dropwise, followed by 5 mL of ammonium persulfate hydrochloric acid solution (containing 60 mg of ammonium persulfate, prepared with 0.5 mol / L hydrochloric acid). Stirring was continued for 12 h after the addition, and the mixture was centrifuged. The solid obtained by centrifugation was alternately washed with anhydrous ethanol and water, and then dried at 60°C to obtain polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (denoted as PANI / RuO2 / CNTs).

[0092] 2) 10 mg of PANI / RuO2 / CNTs was loaded into a porcelain boat and placed in a tube furnace. The temperature was first raised from room temperature to 350°C at a heating rate of 3°C / min, then kept at this temperature for 4 h, and then cooled to room temperature at a cooling rate of 3°C / min to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material (denoted as C / RuO2 / CNTs).

[0093] Performance testing:

[0094] 1) Through SEM and TEM tests, it was found that the microscopic morphology of C / RuO2 / CNTs in this example was highly similar to that of C / RuO2 / CNTs in Example 1, and the particle size of RuO2 nanoparticles and the thickness of the carbon layer were very close.

[0095] 2) The catalyst activity and stability tests (same as in Example 1) showed that the C / RuO2 / CNTs in this example had an OER overpotential of 175 mV, 266 mV, and 198 mV when the electrolyte was a 0.5 mol / L H2SO4 solution, a 1.0 mol / L PBS buffer solution, and a 1.0 mol / L KOH solution, respectively. The HER overpotentials were 62 mV, 41 mV, and 43 mV, respectively, showing ultra-high catalytic activity. After 2000 CV cycles in three different electrolytes, the C / RuO2 / CNTs exhibited a high catalytic activity at a current density of 10 mA / cm 2 The OER and HER overpotentials under these conditions barely increased (<10 mV), demonstrating ultra-high stability.

[0096] Acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (same as in Example 1, denoted as RuO2 / CNTs).

[0097] Performance testing:

[0098] The three-electrode cell was assembled according to the operation of Example 1 to test the catalyst activity. The activity test results were shown in FIG. Figure 7 (a is the OER polarization curve, b is the HER polarization curve).

[0099] Depend on Figure 7 It can be seen that:

[0100] a) OER polarization curves show that the RuO2 / CNTs in this comparative example have OER overpotentials of >600 mV, >600 mV, and 500 mV when the electrolytes are 0.5 mol / L H2SO4 solution, 1.0 mol / L PBS buffer, and 1.0 mol / L KOH solution, respectively. These performances are very unsatisfactory and are much worse than those of the C / RuO2 / CNTs in Examples 1 to 4.

[0101] b) HER polarization curves show that the HER overpotentials of the RuO2 / CNTs in this comparative example are 78 mV, 63 mV, and 70 mV when the electrolytes are 0.5 mol / L H2SO4 solution, 1.0 mol / L PBS buffer, and 1.0 mol / L KOH solution, respectively. This indicates unsatisfactory performance, which is inferior to that of the C / RuO2 / CNTs in Examples 1 to 4.

[0102] In summary, the RuO2 / CNTs in this comparative example are not coated with a carbon layer. Although the HER performance is acceptable, there is almost no OER performance, and it is not suitable for use as a catalyst for electrocatalytic water decomposition to produce hydrogen.

[0103] Comparative Example 2:

[0104] A method for preparing an acidified carbon nanotube loaded with ruthenium dioxide nanoparticles comprises the following steps:

[0105] 10 mg of RuO2 / CNTs (same as Example 1) was loaded into a porcelain boat and placed in a tube furnace. The temperature was first raised from room temperature to 350°C at a heating rate of 3°C / min, then kept warm for 4 hours, and then cooled to room temperature at a cooling rate of 3°C / min to obtain acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles (denoted as RuO2 / CNTs).

[0106] Performance testing:

[0107] The three-electrode cell was assembled according to the operation of Example 1 to test the catalyst activity. The activity test results were shown in FIG. Figure 8 (a is the OER polarization curve, b is the HER polarization curve).

[0108] Depend on Figure 8 It can be seen that:

[0109] a) OER polarization curves show that the RuO2 / CNTs in this comparative example have OER overpotentials of 308 mV, 460 mV, and 315 mV when the electrolytes are 0.5 mol / L H2SO4 solution, 1.0 mol / L PBS buffer, and 1.0 mol / L KOH solution, respectively. These performances are very unsatisfactory and are much worse than those of the C / RuO2 / CNTs in Examples 1 to 4.

[0110] b) HER polarization curves show that the HER overpotentials of the RuO2 / CNTs in this comparative example are 170 mV, 126 mV, and 123 mV when the electrolytes are 0.5 mol / L H2SO4 solution, 1.0 mol / L PBS buffer, and 1.0 mol / L KOH solution, respectively. This indicates unsatisfactory performance, which is worse than that of the C / RuO2 / CNTs in Examples 1 to 4.

[0111] In summary, the RuO2 / CNTs in this comparative example are not coated with a carbon layer and are not suitable for use as a catalyst for electrocatalytic water decomposition to produce hydrogen.

[0112] Comparative Example 3:

[0113] A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, the preparation method of which comprises the following steps:

[0114] 10 mg of PANI / RuO2 / CNTs (same as Example 1) was loaded into a porcelain boat and placed in a tube furnace. The temperature was first raised from room temperature to 300°C at a heating rate of 3°C / min, then kept warm for 4 hours, and then cooled to room temperature at a cooling rate of 3°C / min to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material (denoted as C / RuO2 / CNTs).

[0115] Performance testing:

[0116] The three-electrode cell was assembled according to the operation of Example 1 to test the catalyst activity. The activity test results were shown in FIG. Figure 9 (a is the OER polarization curve, b is the HER polarization curve).

[0117] Depend on Figure 9 It can be seen that:

[0118] a) OER polarization curves show that the RuO2 / CNTs in this comparative example have OER overpotentials of >600 mV, >600 mV, and >600 mV when the electrolytes are 0.5 mol / L H2SO4 solution, 1.0 mol / L PBS buffer, and 1.0 mol / L KOH solution, respectively. These performances are very unsatisfactory and are much worse than those of the C / RuO2 / CNTs in Examples 1 to 4.

[0119] b) HER polarization curves show that the HER overpotentials of the RuO2 / CNTs in this comparative example when the electrolytes are 0.5 mol / L H2SO4 solution, 1.0 mol / L PBS buffer, and 1.0 mol / L KOH solution are 50 mV, 32 mV, and 34 mV, respectively, which are slightly better than those of the C / RuO2 / CNTs in Examples 1 to 4.

[0120] In summary, although the C / RuO2 / CNTs in this comparative example has good HER performance, it has almost no OER performance and is not suitable as a catalyst for electrocatalytic water decomposition to produce hydrogen.

[0121] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A ruthenium dioxide nanoparticle-acidified carbon nanotube composite material, characterized in that: The composition includes acidified carbon nanotubes, ruthenium dioxide nanoparticles and a carbon layer; the ruthenium dioxide nanoparticles are anchored on the surface of the acidified carbon nanotubes; the carbon layer is coated on the surface of the acidified carbon nanotubes and the ruthenium dioxide nanoparticles; the carbon layer is made by calcining polyaniline; the specific operation of the calcination is: first controlling the heating rate to be 2°C / min to 5°C / min from room temperature to 350°C to 500°C, then keeping the temperature for 2h to 4h, and then controlling the cooling rate to be 2°C / min to 5°C / min to cool to room temperature.

2. The ruthenium dioxide nanoparticle-acidified carbon nanotube composite material according to claim 1, characterized in that: The particle size of the ruthenium dioxide nanoparticles is 2nm to 5nm.

3. The ruthenium dioxide nanoparticle-acidified carbon nanotube composite material according to claim 1 or 2, characterized in that: The thickness of the carbon layer is 0.6 nm to 1 nm.

4. A method for preparing the ruthenium dioxide nanoparticle-acidified carbon nanotube composite material according to any one of claims 1 to 3, characterized in that: The following steps are involved: 1) dispersing carbon nanotubes in an acid solution and performing an acidification treatment to obtain acidified carbon nanotubes; 2) dispersing the acidified carbon nanotubes and a soluble ruthenium salt in water for a hydrothermal reaction to obtain the acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles; 3) dispersing the acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles, aniline, and an initiator in water for reaction to obtain polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles; 4) calcining the polyaniline-coated acidified carbon nanotubes loaded with ruthenium dioxide nanoparticles to obtain a ruthenium dioxide nanoparticle-acidified carbon nanotube composite material.

5. The preparation method according to claim 4, characterized in that: Step 1) The acid solution is a mixed acid made of sulfuric acid and nitric acid.

6. The preparation method according to claim 4 or 5, characterized in that: Step 1) The acidification treatment is carried out at 70° C. to 90° C. for 4 to 6 hours.

7. The preparation method according to claim 4, characterized in that: Step 2) The hydrothermal reaction is carried out at 150° C. to 180° C. for 4 to 6 hours.

8. The preparation method according to claim 4, characterized in that: Step 3) The reaction is carried out at 0°C to 5°C for 10 hours to 12 hours.

9. A catalyst for electrocatalytic water decomposition to produce hydrogen, characterized in that: A composite material comprising the ruthenium dioxide nanoparticles and acidified carbon nanotubes according to any one of claims 1 to 3.

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