A boron-ruthenium co-doped tricobalt tetraoxide catalytic material, a preparation method and application thereof

Abstract

The present application relates to a kind of boron ruthenium co-doped cobalt three oxide catalytic material and its preparation method and application, by hydrothermal, pyrolysis, etching three-step method preparation synthesis out with superfine nanoparticle B-Ru-Co3O4 Catalytic material, in alkaline total water splitting condition 10mA cm ‑2 Potential is 1.49V, simulate seawater total water splitting condition 10mA cm ‑2 Potential is 1.54V, using 3.5wt% NaCl as magnesium / seawater battery electrolyte, its maximum power density is 15mW cm ‑2 , and at 2mW cm ‑2 Power density under stable discharge 24h without attenuation.The synthesis method is simple and efficient, while realizing low noble metal loading rate, show higher than commercial noble metal catalyst performance, has broad application prospect.

Description

Technical Field

[0001] This invention belongs to the fields of materials science and technology and power industry technology, specifically relating to a boron-ruthenium co-doped cobalt tetroxide catalytic material, its preparation method and application. Background Technology

[0002] Due to the limited reserves of fossil fuels and the environmental pollution caused by their combustion, energy has become a major problem that urgently needs to be solved by human society. Electrocatalytic water splitting offers a sustainable strategy, providing clean energy through the cathode hydrogen evolution reaction and the anodic oxygen evolution reaction. Seawater on Earth is inexhaustible. Seawater electrolysis can effectively solve the problem of freshwater scarcity. The hydrogen / oxygen evolution reactions in water electrolysis occur at the interface between the catalyst and the electrolyte; therefore, regulating the surface chemical and electronic structures of the catalyst can enhance its intrinsic catalytic activity. According to reports, researchers have employed strategies such as active site regulation, elemental doping, and protective layer construction to optimize the surface structure and electronic state of materials, thereby increasing the intrinsic activity of catalytic sites, exposing more active regions, and protecting active sites from corrosion / poisoning.

[0003] Ru, also a precious metal, is much cheaper than Pt, yet it possesses similar hydrogen adsorption energy, resulting in good HER performance. However, its OER performance is poor, especially at high potentials where Ru is easily oxidized and dissolved, requiring further optimization. Cobalt-based catalysts exhibit suitable adsorption strength for oxygen-containing groups. Therefore, ruthenium-cobalt-based catalysts are considered potential alternatives to commercial catalysts.

[0004] Heteroatom doping is another important strategy for enhancing catalytic activity. Boron doping can induce electron redistribution in metals, modulate the activity of catalytic sites, reduce the thermodynamic and kinetic barriers of the hydrogen evolution / oxygen evolution reaction, and accelerate the reaction. Studies have also shown that anionic catalysts can repel chloride ions during seawater electrolysis, thus slowing down catalyst corrosion.

[0005] Furthermore, most current water / seawater electrolysis systems require an external power source, which is not conducive to large-scale mobile or subsea applications. Magnesium / seawater battery systems use seawater as the electrolyte, providing power for the electrolysis system and also producing hydrogen. The open structure of magnesium / seawater battery electrolysis systems is advantageous for applications in special environments such as the deep sea, showing broad application prospects. Jiang Luhua's team has developed different types of catalysts and applied them to magnesium / seawater batteries. Their carefully designed MoNi / NiMoO4 has a Schottky-like structure and emits up to 21.08 mW / cm³ in magnesium / seawater batteries. 2 The power density was 12.11 mL / cm² at the cathode. 2With a hydrogen evolution rate of / h, the magnesium-hydrogen conversion efficiency is as high as 83.97%. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a boron-ruthenium co-doped cobalt tetroxide catalytic material, its preparation method, and its applications. The B-Ru-Co3O4 catalyst is prepared using a sodium borohydride reduction strategy and a hydrochloric acid etching synthesis method. The borohydride reduction strategy successfully achieves boron doping, which is beneficial for improving the catalytic activity of the catalytic sites. In the simulated seawater electrolysis catalysis process, borate ions repel chloride ions, improving catalytic selectivity. The hydrochloric acid etching method gives the synthesized B-Ru-Co3O4 catalyst a nanoparticle structure, which is beneficial for exposing more catalytic sites. The B-Ru-Co3O4 catalyst, under alkaline total water splitting conditions at 10 mA cm⁻¹, exhibits [further details needed]. -2 The potential is 1.49V, which is relatively low in simulated seawater electrolytes (1.537V@10mAcm). -2 It achieves excellent HER and OER performance; and has a high power density (15mW cm⁻¹) in magnesium / seawater batteries. -2 ), and at 2mW cm -2 It can be discharged stably for 24 hours without decay at a power density.

[0007] Therefore, one of the objectives of this invention is to provide a method for preparing boron-ruthenium co-doped cobalt tetroxide catalytic material, the specific steps of which are as follows:

[0008] (1) Mix a certain amount of cobalt salt, ruthenium salt and sodium borohydride as solute, add deionized water as solvent, stir at room temperature for 1-2 hours under magnetic force until completely dissolved to obtain reaction solution;

[0009] (2) Transfer the reaction solution from (1) to a hydrothermal reactor and perform a hydrothermal reaction in an oven at 120℃-150℃ for 10-12 hours, then allow it to cool naturally to room temperature.

[0010] (3) Take the reaction vessel out of the oven, pour the completely cooled reaction solution into a centrifuge tube and centrifuge, then wash and centrifuge repeatedly with ethanol and deionized water, and finally dry in a freeze dryer for 10-15 hours until freeze-dried to obtain B-Ru-Co3O4 catalyst precursor-1.

[0011] (4) The B-Ru-Co3O4 catalyst precursor-1 obtained in (3) was poured into a ceramic boat and placed in a tube furnace. Under the protection of argon atmosphere, the temperature was raised to 300℃-500℃ at a rate of 5℃ / min and held for 2h. Then it was naturally cooled to room temperature to obtain B-Ru-Co3O4 catalyst precursor-2.

[0012] (5) The B-Ru-Co3O4 catalyst precursor-2 obtained in (4) was etched in hydrochloric acid solution for 12-24h, then washed repeatedly with ethanol and deionized water and centrifuged, and dried overnight in a vacuum oven at 60℃ to obtain boron-ruthenium co-doped cobalt tetroxide catalyst material, namely B-Ru-Co3O4 catalyst.

[0013] In this invention, step (1) is the preparation of the reaction solution. The ruthenium salt in the solute is ruthenium chloride (RuCl3·H2O); the cobalt salt is cobalt chloride (CoCl2·6H2O); the molar concentration ratio of cobalt salt, ruthenium salt and sodium borohydride in the reaction solution is (0.5-1):0.2:(10-20). The molar concentration ratio affects the catalytic performance of the catalyst. Preferably, the concentration of CoCl2·6H2O is 0.04-0.08 mol / L, more preferably 0.08 mol / L, the concentration of RuCl3·H2O is 0.016 mol / L, and the concentration of NaBH4 is 0.8-1.6 mol / L, more preferably 1.6 mol / L; preferably, the mixture is stirred at room temperature for 2 hours under magnetic force.

[0014] In step (2), the hydrothermal reactor is lined with polytetrafluoroethylene, the hydrothermal reaction temperature is preferably 130°C, and the hydrothermal reaction time is preferably 12h.

[0015] In step (3), the centrifugation speed is 10000 r / min, and the freeze-drying time is preferably 15 h.

[0016] In step (4), the preferred calcination temperature is 400°C;

[0017] In step (5), the hydrochloric acid concentration is 1 mol / L, and the etching time is preferably 24 h.

[0018] In this invention, ethanol and deionized water are used to wash the product alternately 4-6 times.

[0019] A second objective of this invention is to provide a B-Ru-Co3O4 catalyst prepared by the above method, which has a morphology of ultrafine nanoparticles with an average particle size of 5-10 nanometers. Metallic Ru serves as the active site, accelerating the reaction rate during the catalytic reaction. Boron is oxidized to borates during the catalytic reaction, effectively repelling chloride ions in seawater and significantly improving the catalyst's corrosion resistance in seawater environments. The uniformly distributed co-doped structure of boron, ruthenium, and cobalt in the nanoparticle structure significantly contributes to improving the catalyst's catalytic performance and corrosion resistance.

[0020] A third objective of this invention is to provide an application of the above-mentioned B-Ru-Co3O4 catalyst in alkaline water splitting and / or simulated seawater water splitting, as well as its use as a cathode catalyst in magnesium / seawater batteries. Under alkaline water splitting conditions at 10 mA cm⁻¹ -2 The potential is 1.49V, simulating the total hydrolysis of seawater at 10mA cm⁻¹. -2 The potential is 1.54V; as a cathode material in simulated seawater electrolysis, it can significantly reduce the overpotential of hydrogen evolution reaction and oxygen evolution reaction, exhibiting excellent catalytic activity and selectivity in seawater electrolysis; using 3.5wt% NaCl aqueous solution as electrolyte and B-Ru-Co3O4 catalyst as cathode catalyst in magnesium / seawater battery, the highest discharge power density can reach 15mW / cm². 2 It also exhibits extremely long-term stability at 2mW cm⁻¹. -2 It exhibits stable discharge for 24 hours at a high power density without attenuation, demonstrating promising application prospects.

[0021] In this invention, a sodium borohydride reduction strategy and a hydrochloric acid etching synthesis method were used to prepare the B-Ru-Co3O4 catalyst. Sodium borohydride in the reaction solute acts as a reducing agent during the hydrothermal reaction, regulating the electronic structure of ruthenium / cobalt to obtain zero-valent ruthenium and cobalt with both divalent and trivalent valences, playing a crucial role in improving catalytic performance. Simultaneously, during the catalytic reaction, boron doping is oxidized to borate ions in seawater electrolysis, which helps to repel chloride ions and improves the selectivity and corrosion resistance of the OER. During the preparation process, 1 mol / L hydrochloric acid solution was used for etching. The etching time directly affects the catalyst morphology; the longer the etching time, the more uniform the particle size. B-Ru-Co3O4 has an ultrafine nanoparticle structure, which has a large specific surface area, facilitating the exposure of more catalytic sites. When the above-mentioned B-Ru-Co3O4 with the ultrafine nanoparticle structure was placed in a membrane electrode testing system, high current density could be achieved at low voltage under alkaline conditions and simulated seawater conditions, and it also exhibited good stability.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] 1. This invention successfully achieves boron doping, which improves catalytic performance by regulating the electronic structure, and enhances catalytic selectivity and corrosion resistance of borate ions during seawater electrolysis catalysis.

[0024] 2. This invention employs hydrochloric acid etching during the synthesis process, allowing the ultrafine nanoparticle structure to expose more catalytic sites. It exhibits excellent HER and OER performance in simulated seawater, achieving results at 10 mA cm⁻¹. -2It exhibits low overpotentials (25mV, 270mV). It significantly improves energy efficiency and reduces energy consumption in seawater electrolysis, making it suitable for large-scale industrial production and showing promising application prospects.

[0025] 3. The B-Ru-Co3O4 catalyst synthesized in this invention, when used as the cathode in a magnesium / seawater battery with a magnesium alloy as the anode and a 3.5 wt% NaCl aqueous solution as the electrolyte, exhibits a high power density (15 mW / cm²). 2 ) and discharge stability (24h@2mW / cm 2 This surpasses most reported magnesium / seawater battery cathode catalysts. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the B-Ru-Co3O4 catalyst.

[0027] Figure 2 High-magnification transmission electron microscopy feature image of B-Ru-Co3O4 catalyst.

[0028] Figure 3 The graph shows the overall decomposition performance of the B-Ru-Co3O4 catalyst under alkaline conditions.

[0029] Figure 4 The graph shows the overall decomposition performance of the B-Ru-Co3O4 catalyst under alkaline seawater conditions.

[0030] Figure 5 This is a power density diagram of the B-Ru-Co3O4 catalyst in a magnesium / seawater battery.

[0031] Figure 6 This is a rate discharge diagram of the B-Ru-Co3O4 catalyst in a magnesium / seawater battery.

[0032] Figure 7 The figure shows the discharge stability of the B-Ru-Co3O4 catalyst in a magnesium / seawater battery. Detailed Implementation

[0033] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0034] Example 1:

[0035] (1) Weigh 0.285g of CoCl2·6H2O, 0.052g of RuCl3·H2O and 0.908g of NaBH4 and mix them as solutes. Add 15mL of deionized water as solvent and stir at room temperature for 2h under magnetic force until completely dissolved to obtain the reaction solution.

[0036] (2) Transfer the reaction solution in (1) into a 25 mL polytetrafluoroethylene liner, and perform a hydrothermal reaction in an oven at 130 °C for 12 h, and then allow it to cool naturally to room temperature.

[0037] (3) Take the reaction vessel out of the oven, pour the completely cooled reaction solution into a centrifuge tube and centrifuge at 10000 r / min. Then wash and centrifuge with ethanol and deionized water alternately. Repeat washing and centrifugation 6 times. Finally, dry in a freeze dryer for 15 h until freeze-dried to obtain B-Ru-Co3O4 catalyst precursor-1.

[0038] (4) Pour the B-Ru-Co3O4 catalyst precursor-1 obtained in (3) into a ceramic boat, place it in a tube furnace, and heat it at 5℃ / min under an argon atmosphere. - The temperature was increased to 400℃ at a certain rate and held for 2 hours, and then naturally cooled to room temperature to obtain B-Ru-Co3O4 catalyst precursor-2.

[0039] (5) The B-Ru-Co3O4 catalyst precursor-2 obtained in (4) was etched in 1 mol / L hydrochloric acid solution for 24 h, then washed with ethanol and deionized water alternately and centrifuged 6 times, and finally dried in a vacuum oven at 60 °C overnight to obtain boron-ruthenium co-doped cobalt tetroxide catalyst material, namely B-Ru-Co3O4 catalyst.

[0040] Example 2:

[0041] Similar to Example 1, except that in step (1), 0.285g of CoCl2·6H2O, 0.052g of RuCl3·H2O, and 0.454g of NaBH4 were weighed and mixed as solutes to prepare the B-Ru-Co3O4 catalyst. The catalyst exhibited a stability of 10% attenuation after 10 hours in a simulated seawater environment, and a total decomposition catalytic performance of 1.56V@10mA cm⁻¹. -2 .

[0042] Example 3:

[0043] Same as Example 1, except that in step (1), 0.143g of CoCl2·6H2O, 0.052g of RuCl3·H2O, and 0.908g of NaBH4 were weighed and mixed as solutes to prepare the B-Ru-Co3O4 catalyst with a total decomposition catalytic performance of 1.53V@10mAcm. -2 .

[0044] Comparative Example 1:

[0045] Similar to Example 1, except that ruthenium salt (RuCl3·H2O) is not added in step (1), and the molar ratio of cobalt salt, ruthenium salt and sodium borohydride in the reaction solution is 1:0:20. The catalytic performance of the resulting catalyst is greatly reduced (total water splitting under alkaline conditions: 1.82V@10mA cm). -2 This confirms that the Ru site has a significant impact on catalytic activity.

[0046] Comparative Example 2:

[0047] Similar to Example 1, the difference is that NaBH4 is not added in step (1). The resulting catalyst exhibits poor stability in simulated seawater conditions (25% degradation after 10 hours), and its catalytic performance also decreases (total water splitting under alkaline conditions: 1.64V@10mA cm⁻¹). -2 This study confirms that boron atom doping contributes to improving corrosion resistance and regulating the activity of catalytic sites.

[0048] like Figure 1 As shown in the scanning electron microscope image, the morphology of the B-Ru-Co3O4 catalyst prepared in Example 1 is a nanoparticle structure.

[0049] The transmission electron microscopy image of the B-Ru-Co3O4 catalyst obtained in Example 1 is shown below. Figure 2 As shown, the nanoparticle structure has an ultrafine particle size, with an average particle size of approximately 5-10 nanometers. The ultrafine nanoparticles obtained by hydrochloric acid etching have a larger specific surface area, increasing the catalytic reaction area and thus improving the catalytic reaction rate.

[0050] The LSV diagram of alkaline total water splitting of the B-Ru-Co3O4 catalyst prepared in Example 1 is shown below. Figure 3 As shown, the LSV curve displays 10 mA cm -2 The potential is 1.49V, which is less than that of a commercially available platinum-carbon and ruthenium dioxide combination (10 mA cm⁻¹). -2 The value below 1.61V indicates that B-Ru-Co3O4 has a higher overall water splitting efficiency.

[0051] The simulated seawater total water splitting LSV diagram of the B-Ru-Co3O4 catalyst prepared in Example 1 is shown below. Figure 4 As shown, the LSV curve displays 10 mA cm -2 The potential is 1.54V, and compared with alkaline water electrolysis, there is only a 50mV overpotential decay, indicating that B-Ru-Co3O4 has certain anti-corrosion properties and the possibility of application in seawater electrolysis.

[0052] The power density diagram of the B-Ru-Co3O4 catalyst prepared in Example 1 in a magnesium / seawater battery is shown below. Figure 5 As shown, the maximum power density reaches 15 mW / cm².-2 This surpasses the performance of most reported magnesium / seawater batteries, demonstrating the applicability of B-Ru-Co3O4 in magnesium / seawater batteries.

[0053] The rate discharge diagram of the B-Ru-Co3O4 catalyst prepared in Example 1 in a magnesium / seawater battery is shown below. Figure 6 As shown, the discharge power density is 2mW / cm². -2 4mW cm -2 6mW cm -2 8mW cm -2 . Figure 6 The results show that the magnesium / seawater battery has a constant voltage under different discharge rates, indicating that B-Ru-Co3O4 has a certain degree of corrosion resistance in magnesium / seawater battery applications.

[0054] The discharge stability diagram of the B-Ru-Co3O4 catalyst prepared in Example 1 in a magnesium / seawater battery is shown below. Figure 7 As shown, at 2mW cm -2 The battery can be stably discharged for 24 hours at a high power density without any degradation, which further demonstrates the corrosion resistance of B-Ru-Co3O4 and its feasibility for application in magnesium / seawater batteries.

Claims

1. A method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material, characterized in that, The specific steps include the following: (1) Mix a certain amount of cobalt salt, ruthenium salt and sodium borohydride as solute, add deionized water as solvent, stir at room temperature for 1-2 hours under magnetic force until completely dissolved to obtain reaction solution; the molar concentration ratio of cobalt salt, ruthenium salt and sodium borohydride in reaction solution is (0.5-1):0.2:(10-20); (2) Transfer the reaction solution from (1) to a hydrothermal reactor and perform a hydrothermal reaction in an oven at 120℃-150℃ for 10-12 hours, then allow it to cool naturally to room temperature. (3) Take the reaction vessel out of the oven, pour the completely cooled reaction solution into a centrifuge tube and centrifuge, then wash and centrifuge repeatedly with ethanol and deionized water, and finally dry in a freeze dryer for 10-15 hours until freeze-dried to obtain B-Ru-Co3O4 catalyst precursor-1. (4) The B-Ru-Co3O4 catalyst precursor-1 obtained in (3) was poured into a ceramic boat and placed in a tube furnace. Under the protection of argon atmosphere, the temperature was raised to 300℃-500℃ at a rate of 5℃ / min and held for 2h. Then it was naturally cooled to room temperature to obtain B-Ru-Co3O4 catalyst precursor-2. (5) The B-Ru-Co3O4 catalyst precursor-2 obtained in (4) was etched in hydrochloric acid solution for 12-24h, then washed repeatedly with ethanol and deionized water and centrifuged, and dried overnight in a vacuum oven at 60℃ to obtain boron-ruthenium co-doped cobalt tetroxide catalyst material, namely B-Ru-Co3O4 catalyst.

2. The method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material according to claim 1, characterized in that, In step (1), the concentration of cobalt salt in the reaction solution is 0.04-0.08 mol / L, the concentration of ruthenium salt is 0.016 mol / L, and the concentration of sodium borohydride is 0.8-1.6 mol / L.

3. The method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material according to claim 2, characterized in that, The cobalt salt is CoCl2·6H2O with a concentration of 0.08 mol / L, the ruthenium salt is RuCl3·H2O with a concentration of 0.016 mol / L, and the NaBH4 concentration is 1.6 mol / L.

4. The method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material according to claim 1, characterized in that, In step (2), the hydrothermal reactor is lined with polytetrafluoroethylene, the hydrothermal reaction temperature is 130℃, and the hydrothermal reaction time is 12h.

5. The method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material according to claim 1, characterized in that, In step (3), the centrifugation speed is 10000 r / min and the freeze-drying time is 15 h.

6. The method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material according to claim 1, characterized in that, In step (4), the calcination temperature is 400℃; in step (5), the hydrochloric acid concentration is 1mol / L and the etching time is 24h.

7. The method for preparing a boron-ruthenium co-doped cobalt tetroxide catalytic material according to claim 1, characterized in that, In steps (3) and (5), the fingers are washed 4-6 times alternately with ethanol and deionized water.

8. The B-Ru-Co3O4 catalyst prepared by the method according to any one of claims 3-7, characterized in that, The catalyst has an ultrafine nanoparticle structure with a size of 5-10 nanometers.

9. The application of the B-Ru-Co3O4 catalyst according to claim 8 in alkaline total water splitting and / or simulated seawater total water splitting, as well as as a cathode catalyst in magnesium / seawater batteries.

10. The application according to claim 9, characterized in that, The B-Ru-Co3O4 catalyst, under alkaline total water splitting conditions, at 10 mA cm⁻¹ -2 The potential is 1.49V, simulating the total hydrolysis of seawater at 10mA cm⁻¹. -2 The potential is 1.54V, and 3.5wt% NaCl is used as the electrolyte for the magnesium / seawater battery. Its maximum power density is 15mW / cm². -2 And at 2mW cm -2 It can be discharged stably for 24 hours without decay at a power density.

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