Titanium-based self-supporting electrolytic seawater anode catalytic material and preparation method thereof

Abstract

The invention discloses a titanium-based self-supporting electrolytic seawater anode catalytic material and a preparation method thereof in novel electrocatalytic materials. The catalytic material is composed of a cobalt titanate nanowire network growing on foamed titanium, cobaltosic oxide nanoparticles dispersed in the nanowire network and graphene oxide covering the surface of the nanowire network. Firstly, an alkali liquor etching-ion exchange method is used for growing a cobalt titanate nanowire network on the surface of foamed titanium in situ to serve as a supporting framework, and then a hydrothermal method is used for growing cobaltosic oxide nanoparticles in the cobalt titanate nanowire network, so that a catalytic component is highly stable and is not prone to falling off; and finally, the surface of the cobalt titanate nanowire network is covered with graphene oxide through an electro-deposition method, an integrated self-supporting electrode is constructed, the chloride ion repulsion effect is further enhanced, the oxygen evolution activity and chlorine resistance are synchronously improved, the nanostructure is protected against corrosion of complex components of seawater, and the electrode has efficient and stable electro-catalytic performance as an electrolytic seawater anode. The electrode service life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of new electrocatalytic materials technology, specifically relating to a titanium-based self-supporting anode catalytic material for seawater electrolysis and its preparation method. Background Technology

[0002] Hydrogen production via water electrolysis driven by renewable energy is a crucial technology for achieving the national "dual-carbon" and clean energy strategic goals, boasting advantages such as high efficiency, environmental friendliness, and pure products. Oceans cover approximately 96.5% of the Earth's water and are rich in solar, wind, and tidal energy, making them an ideal location for hydrogen production by combining unlimited water resources with renewable electricity. However, unlike traditional electrocatalytic water splitting using freshwater as feedstock, direct seawater electrolysis is constrained by the complex composition and corrosiveness of seawater. To date, no ideal catalytic material has been developed that is fully adaptable to the seawater environment, becoming a bottleneck for the development of the marine green hydrogen industry. In addition to the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, numerous competing side reactions exist during the electrocatalytic splitting of seawater. In particular, chloride ions tend to accumulate at the anode and undergo chlorination, leading to poisoning and corrosion of the catalytic electrode, severely reducing electrolysis efficiency and stability. Therefore, improving the chlorine-repellent and oxygen evolution reaction performance of the anode material is a key issue that urgently needs to be addressed to achieve efficient and stable direct seawater electrolysis for hydrogen production.

[0003] Currently, researchers are improving the chloride-repellent and oxygen-evolution performance of anode materials through various methods, including constructing a manganese oxide chloride ion blocking layer (Inorg.Chem.2022,61,15256-15265), introducing phytic acid complexes, and PO4. 3- SO4 2- The plasmon anion layer (Adv. Energy Mater. 2023, 13, 2303360; Chem. Eng. J. 2023, 460, 141413; Angew. Chem. Int. Ed. 2021, 60, 22740-22744) incorporates Cr, Mo, and W into the lattice of a nickel-based compound and forms CrO4 in situ. 2- MoO4 2- W2O7 2- Strongly negatively charged layers, etc. (Angew. Chem. Int. Ed. 2023, 62, e202309854; Nat. Commun. 2023, 14, 3607; Appl. Catal. B-Environ. 2023, 330, 122612), thus affecting Cl. -Effective repulsion is achieved. However, most existing studies use nickel foam or nickel-based materials as the matrix. Although these materials exhibit some stability in alkaline electrolytes, their intrinsic electrocatalytic activity easily leads to reconstruction, resulting in structural degradation. In contrast, titanium-based materials possess superior chemical stability and can even be used in acidic environments. However, the intrinsic catalytic inertness of titanium-based materials means they are mostly used only as current collectors in supported electrodes, where catalyst powder and binder are co-supported on a titanium matrix. This supported structure suffers from high interfacial resistance and catalyst detachment issues. For example, Chinese Patent Publication No. CN120210887A, entitled "Titanium-based Catalytic Anode for Hydrogen Production by Water Electrolysis and its Preparation Method," reports a titanium-based catalytic anode comprising a titanium matrix and a catalyst layer covering the surface. The catalyst layer is a slurry coating formed by mixing cerium-zirconium solid solution powder and a noble metal catalyst, or formed by depositing a cerium-zirconium solid solution supported on a noble metal catalyst onto the surface of the titanium matrix. This is essentially a supported structure and lacks chlorine repulsion functionality specific to marine environments. Therefore, developing a self-supporting titanium-based catalytic anode with high activity, high stability, and chlorine repellency is crucial for the practical application of seawater electrolysis for hydrogen production. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, one objective of this invention is to provide a titanium-based self-supporting electrolytic seawater anode catalyst material that can enhance the chlorine-repellent and oxygen-evolution performance of anode materials for marine environments.

[0005] To achieve one of the above objectives, the present invention provides a titanium-based self-supporting anode catalyst for seawater electrolysis, which is implemented by the following technical solution: it is composed of a cobalt titanate nanowire network grown on foamed titanium, cobalt tetroxide nanoparticles dispersed in the nanowire network, and graphene oxide covering the surface of the nanowire network.

[0006] Preferably, the cobalt titanate nanowires have a diameter of 30–50 nm, the cobalt tetroxide nanoparticles have a size of 20–50 nm, and the graphene oxide on the surface of the nanowire network is a single layer.

[0007] The second objective of this invention is to provide a method for preparing a titanium-based self-supporting anode catalyst for seawater electrolysis. The catalytic components of the prepared catalyst are highly stable, which can extend the service life of the electrode.

[0008] The present invention discloses a method for preparing a titanium-based self-supporting anode catalyst for seawater electrolysis, which includes the following steps:

[0009] (1) In-situ growth of cobalt titanate nanowire network on the surface of titanium foam

[0010] First, the foamed titanium is soaked in an alkaline solution and then washed with deionized water until the washing solution is neutral. It is then vacuum dried for later use. Next, the treated foamed titanium is soaked in a cobalt salt solution to complete ion exchange, washed with deionized water, and vacuum dried to obtain a cobalt titanate nanowire network / foamed titanium.

[0011] (2) Growth of cobalt tetroxide nanoparticles within a cobalt titanate nanowire network

[0012] First, Co(NO3)2·6H2O is dissolved in a mixed solvent composed of ethanol and deionized water to form a cobalt nitrate solution; then, ammonia water is added while stirring, and the cobalt nitrate solution with added ammonia water is transferred to a reaction vessel lined with polytetrafluoroethylene.

[0013] The cobalt titanate nanowire network / foam titanium obtained in step (1) is placed in a reaction vessel, sealed, and reacted at 80°C to grow cobalt tetroxide nanoparticles in the cobalt titanate nanowire network, thus obtaining cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foam titanium; finally, the cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foam titanium is taken out, thoroughly washed with deionized water, and vacuum dried for later use.

[0014] (3) Coating the surface of the cobalt titanate nanowire network with graphene oxide

[0015] Using the dried cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foam titanium obtained in step (2) as the working electrode, Ag / AgCl electrode as the reference electrode, carbon rod as the counter electrode, and graphene oxide dispersion as the electrolyte, constant potential deposition was performed to cover the surface of the nanowire network with a single layer of graphene oxide.

[0016] Preferably, the alkaline solution in step (1) is 10 mL / L. -1 KOH or NaOH solution.

[0017] Preferably, in step (1), the foamed titanium is soaked in alkaline solution at 80-90°C for 6-8 hours, and the foamed titanium is soaked in cobalt salt solution at 80-90°C for 12-18 hours.

[0018] Preferably, the cobalt salt solution in step (1) is a divalent cobalt strong electrolyte solution.

[0019] Preferably, in step (2), the mass-to-volume ratio of Co(NO3)2·6H2O to the mixed solvent is (0.1–0.5 g):(30 mL), the volume ratio of ammonia to cobalt nitrate solution is 1:6, and the ratio of the area of ​​the cobalt titanate nanowire network / foam titanium to the volume of the mixed liquid in the reactor is (1–2 cm²). 2 ):(35mL), cobalt titanate nanowire network / foam titanium was placed in the reaction vessel and sealed, and reacted at 80℃ for 8-12h.

[0020] Preferably, the graphene oxide dispersion in step (3) is a single layer of graphene oxide dispersed in deionized water at a mass concentration of 0.5 mg / mL. -1 This is the optimal solution.

[0021] Preferably, the deposition potential during constant potential deposition in step (3) is -1.1V (vs.Ag / AgCl), and the deposition time is 40-160s.

[0022] Compared with the prior art, the significant advantages of this invention are:

[0023] (1) Using foamed titanium as a substrate, a cobalt titanate nanowire network was grown in situ as a supporting framework, and cobalt tetroxide nanoparticles were uniformly loaded inside the network to make the catalytic components highly stable and not easily detached. Finally, an integrated self-supporting electrode was constructed by firmly coating a graphene oxide layer through electrodeposition technology, which significantly improved the structural stability and catalytic efficiency of the electrode.

[0024] (2) Synergistic catalysis and chloride repulsion. The cobalt titanate nanowire network not only provides a high specific surface area and conductive framework, but its oxygen-containing anion properties can also effectively repel chloride ions, preventing the active sites from being poisoned. At the same time, the hydrogen bonding between titanate and hydroxide ions can promote the transport and adsorption of OH-, thereby simultaneously improving oxygen evolution activity and chloride resistance. In addition, the graphene oxide coating on the surface further enhances the chloride ion repulsion effect, protects the nanostructure from corrosion by the complex components of seawater, and extends the service life of the electrode.

[0025] (3) The preparation process is green and efficient, with broad application prospects. A three-step method involving alkaline etching-ion exchange, hydrothermal reaction, and electrodeposition is employed to prepare the high-performance self-supporting titanium-based catalytic electrode. This method is simple, operates under mild conditions, and eliminates the need for energy-intensive steps such as high-temperature calcination, thus yielding a high-performance self-supporting titanium-based catalytic electrode. This electrode is suitable for use in seawater and high-salinity electrolytes, exhibiting excellent chlorine-repellent and oxygen-evolution performance, providing a reliable electrode material solution for the large-scale development of marine green hydrogen. In summary, this invention, through material innovation and structural optimization, improves catalytic activity while solving problems such as easy corrosion and poor stability of traditional electrodes, demonstrating significant potential for industrial application. Attached Figure Description

[0026] Figure 1 The image shows a scanning electron microscope (SEM) image of K2Ti4O9 / Ti in Example 1.

[0027] Figure 2 Co in Example 1 x SEM images of Ti4O9 / Ti;

[0028] Figure 3 Co3O4 / Co in Example 1 x SEM images of Ti4O9 / Ti;

[0029] Figure 4 For example, 80-GO / Co3O4 / Co x SEM images of Ti4O9 / Ti;

[0030] Figure 5 For example 1, from 80-GO / Co3O4 / Co x Co3O4 / Co ultrasonically dissipated from Ti4O9 / Ti self-supporting material x TEM images of Ti4O9 nanowires and nanoparticles ( Figure 5 a and Figure 5 b) and element distribution map ( Figure 5 c);

[0031] Figure 6 For example, 80-GO / Co3O4 / Co x XRD pattern of Ti4O9 / Ti;

[0032] Figure 7 For example, 80-GO / Co3O4 / Co x XPS spectra of Ti4O9 / Ti. Figure 7 (a) is the full spectrum; Figure 7 (b) is the high-resolution spectrum of Co 2p; Figure 7 (c) is the high-resolution spectrum of O1s; Figure 7 (d) is the high-resolution C1s spectrum; Figure 7 (e) is the high-resolution spectrum of Ti 2p;

[0033] Figure 8 For example, 80-GO / Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 Linear sweep voltammetry (LSV) curves in KOH solution;

[0034] Figure 9 For example, 80-GO / Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 LSV curve of KOH + natural seawater;

[0035] Figure 10 For example, 80-GO / Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 Current-time curve of KOH + natural seawater;

[0036] Figure 11 For example, 40-GO / Co3O4 / Co xSEM images of Ti4O9 / Ti;

[0037] Figure 12 For example, 40-GO / Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 LSV curve in KOH solution;

[0038] Figure 13 For example, 40-GO / Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 LSV curve of KOH + natural seawater;

[0039] Figure 14 For example, 160-GO / Co3O4 / Co in Example 3 x SEM images of Ti4O9 / Ti;

[0040] Figure 15 For example, 160-GO / Co3O4 / Co in Example 3 x Ti4O9 / Ti in 1 mol L -1 LSV curve in KOH solution;

[0041] Figure 16 For example, 160-GO / Co3O4 / Co in Example 3 x Ti4O9 / Ti in 1 mol L -1 LSV curve of KOH + natural seawater;

[0042] Figure 17 For example, 0.1-Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 LSV curve in KOH solution;

[0043] Figure 18 For example, 0.5-GO / Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 LSV curve in KOH solution. Detailed Implementation

[0044] This invention discloses a titanium-based self-supporting anode catalyst for seawater electrolysis, comprising a cobalt titanate nanowire network grown on foamed titanium, cobalt tetroxide nanoparticles dispersed within the nanowire network, and graphene oxide covering the surface of the nanowire network. The cobalt titanate nanowires have a diameter of 30–50 nm, the cobalt tetroxide nanoparticles have a size of 20–50 nm, and the graphene oxide covering the nanowire network is a single layer.

[0045] The preparation method of the titanium-based self-supporting electrolytic seawater anode catalyst involves first growing a cobalt titanate nanowire network in situ on the surface of foamed titanium using an alkaline etching-ion exchange method, then growing cobalt tetroxide nanoparticles within the cobalt titanate nanowire network using a hydrothermal method, and finally coating the surface of the cobalt titanate nanowire network with graphene oxide using an electrodeposition method. The details are as follows:

[0046] (1) Cobalt titanate nanowire networks were grown in situ on the surface of titanium foam using an alkaline etching-ion exchange method.

[0047] Immerse the foamed titanium in an alkaline solution, preferably using a 10 mL / L solution. -1 The solution is preferably soaked in KOH or NaOH solution at 80-90℃ for 6-8 hours, then rinsed with deionized water until the cleaning solution is neutral, and then vacuum dried for later use.

[0048] The vacuum-dried, alkaline-treated titanium foam is immersed in a cobalt salt solution for ion exchange, preferably at 80-90°C for 12-18 hours. The cobalt salt solution is a divalent cobalt strong electrolyte solution, with Co(NO3)2·6H2O solution being optimal. It is then washed with deionized water and vacuum dried to obtain a cobalt titanate nanowire network / titanium foam.

[0049] (2) Growth of cobalt tetroxide nanoparticles within a cobalt titanate nanowire network using a hydrothermal method

[0050] Co(NO3)2·6H2O is dissolved in a mixed solvent of ethanol and deionized water to form a cobalt nitrate solution. Preferably, the mass-to-volume ratio of Co(NO3)2·6H2O to the mixed solvent is (0.1–0.5 g):(30 mL). Ammonia is then added to the cobalt nitrate solution while stirring. Preferably, the volume ratio of ammonia to cobalt nitrate solution is 1:6. The mixture of ammonia and cobalt nitrate solution is then transferred to a polytetrafluoroethylene-lined reactor.

[0051] The cobalt titanate nanowire network / foam titanium obtained in step (1) is also placed into the reactor. Preferably, the ratio of the area of ​​the cobalt titanate nanowire network / foam titanium to the volume of the mixed liquid in the reactor is (1-2 cm²). 2 ):(35mL), seal the reaction vessel and react, preferably at 80℃ for 8-12h. Grow cobalt tetroxide nanoparticles in the cobalt titanate nanowire network to obtain cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foamed titanium; finally, take out the cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foamed titanium sample, wash thoroughly with deionized water, and vacuum dry for later use.

[0052] (3) Graphene oxide was coated onto the surface of a cobalt titanate nanowire network using an electrodeposition method.

[0053] Using the cobalt tetroxide nanoparticles / cobalt titanate nanowire network / titanium foam obtained in step (2) as the working electrode, an Ag / AgCl electrode as the reference electrode, a carbon rod as the counter electrode, and a graphene oxide dispersion as the electrolyte, constant potential deposition is performed to coat a single layer of graphene oxide on the surface of the nanowire network. The preferred deposition potential is -1.1V (vs. Ag / AgCl), and the deposition time is 40-160s; preferably, the graphene oxide dispersion is a single layer of graphene oxide dispersed in deionized water at a mass concentration of 0.5 mg / mL. -1 This is the optimal solution.

[0054] To better understand the essence of the present invention, the present invention will be further described below with reference to five embodiments.

[0055] Example 1

[0056] Electrodeposition of 80s graphene oxide / cobalt tetroxide / cobalt titanate / titanium (80-GO / Co3O4 / Co) x Preparation, characterization and performance testing of Ti4O9 / Ti

[0057] (1) Cobalt titanate nanowire networks were grown in situ on the surface of titanium foam using an alkaline etching-ion exchange method.

[0058] Add titanium foam to 10 mol L -1 The potassium titanate nanowire network / foamed titanium (K2Ti4O9 / Ti) precursor was obtained by soaking in KOH at 90℃ for 6 hours, washing with deionized water until the washing solution was neutral, and drying in a vacuum drying oven at 60℃ overnight. -1 The cobalt titanate nanowire network / foamed titanium was obtained by soaking in a Co(NO3)2·6H2O solution at 80℃ for 12 hours to complete ion exchange, washing with deionized water, and vacuum drying. x Ti4O9 / Ti).

[0059] Figure 1 The image shows a SEM image of K2Ti4O9 / Ti obtained after alkaline etching, revealing the potassium titanate nanowire network structure. Figure 2 Co obtained after ion exchange x SEM images of Ti4O9 / Ti show a cobalt titanate nanowire network structure with nanowire diameters of 30–50 nm.

[0060] (2) Growth of cobalt tetroxide nanoparticles within a cobalt titanate nanowire network using a hydrothermal method

[0061] 0.3 g of Co(NO3)2·6H2O was dissolved in a mixed solvent consisting of 15 mL of ethanol and 15 mL of deionized water, with a mass-to-volume ratio of Co(NO3)2·6H2O to the mixed solvent of 0.3 g: 30 mL. Then, while stirring, 5 mL of ammonia solution was added, with a volume ratio of ammonia solution to cobalt nitrate solution of 1:6. The mixed solution was then transferred to a 70 mL polytetrafluoroethylene-lined reactor. The Co... x Ti4O9 / Ti was added to the reactor, and Co was then added. x The ratio of the area of ​​Ti4O9 / Ti to the volume of the mixed liquid in the reactor is 1 cm². 2 35 mL of the sample was sealed and reacted at 80 °C for 10 h to grow cobalt tetroxide nanoparticles in a cobalt titanate nanowire network. Finally, the sample was removed, thoroughly washed with deionized water, and vacuum dried to obtain cobalt tetroxide nanoparticles / cobalt titanate nanowire network / titanium foam (Co3O4 / Co). x Ti4O9 / Ti).

[0062] Figure 3 Co3O4 / Co x SEM images of Ti4O9 / Ti show that a large number of cobalt tetroxide nanoparticles have grown in the cobalt titanate nanowire network, with a particle size of approximately 20 nm.

[0063] (3) Graphene oxide was coated onto the surface of a cobalt titanate nanowire network using an electrodeposition method.

[0064] With 80-Co3O4 / Co x Ti4O9 / Ti was used as the working electrode, Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode. (0.5 mg / mL) -1 A graphene oxide dispersion was used as the electrolyte for constant potential deposition. The deposition potential was set to -1.1V (vs. Ag / AgCl), and the deposition time was set to 80s. A monolayer of graphene oxide was deposited on the surface of the nanowire network to obtain graphene oxide / cobalt tetroxide nanoparticles / cobalt titanate nanowire network / titanium foam (80-GO / Co3O4 / Co). x Ti4O9 / Ti).

[0065] Figure 4 For GO / Co3O4 / Co x SEM images of Ti4O9 / Ti show that the surface of the nanowire network is covered with a layer of graphene oxide, which is a single-layer structure.

[0066] Figure 5 a and Figure 5 b represents the value from 80-GO / Co3O4 / Co x Co ultrasonically removed from Ti4O9 / Ti self-supporting material xTEM images of Ti4O9 nanowires and Co3O4 nanoparticles. Figure 5 c is the corresponding elemental distribution diagram, which clearly shows that the nanowires are composed of Ti, Co, and O, while the nanoparticles are composed of Co and O.

[0067] Figure 6 80-GO / Co3O4 / Co x The XRD pattern of Ti4O9 / Ti shows that the sharp Ti diffraction peak originates from the foamed titanium substrate, while the remaining diffraction peaks originate from Co3O4 nanoparticles, and GO and Co... x Ti4O9 was too weak to be distinguished in the spectrum.

[0068] Figure 7 a is 80-GO / Co3O4 / Co x The XPS full spectrum of Ti4O9 / Ti shows Co, Ti, and O elements. The presence of the N signal is due to the use of Co(NO3)2 during the material preparation process. Figure 7 b-7e represent the high-resolution spectra and peak fitting results of Co, O, C, and Ti, respectively, proving that GO, Co3O4, and Co... x The bonding states of elements in Ti4O9.

[0069] (4)GO / Co3O4 / Co x Performance testing of Ti4O9 / Ti as a self-supporting anode catalyst for seawater electrolysis

[0070] A three-electrode system was adopted, with GO / Co3O4 / Co x Ti4O9 / Ti was used as the working electrode, Hg / HgO as the reference electrode, and a graphite rod as the counter electrode. 1 mol L -1 KOH or alkaline seawater (1 mol L) -1 Using KOH and natural seawater as the electrolyte, linear sweep voltammetry (LSV) was performed. To evaluate the stability of the material, chronoamperometry was conducted at a potential of 1.445V (vs. RHE).

[0071] Figure 8 For 1 mol L -1 The LSV curve of KOH shows that it only requires an overpotential of 215mV to achieve a current density of 10mA cm-2.

[0072] Figure 9 The LSV curve in alkaline seawater shows that an overpotential of only 240 mV is required to achieve a current density of 10 mA cm⁻², which is not much different from that of alkaline pure water electrolyte, indicating that it has excellent anodic catalytic activity for water electrolysis.

[0073] Figure 10The chronoamperometry curve in alkaline seawater shows that the current density remained around 80% after 38 hours of testing, indicating that the GO / Co3O4 / Co... x Ti4O9 / Ti exhibits high stability in seawater.

[0074] Example 2

[0075] Electrodeposition of graphene oxide / cobalt tetroxide / cobalt titanate / titanium (40-GO / Co3O4 / Co) for 40 s x Preparation, characterization and performance testing of Ti4O9 / Ti

[0076] The difference from Example 1 is: 1. The alkaline solution in step (1) is 10 mL / L. -1 NaOH solution, soaked at 80°C for 8 hours, and then the foamed titanium was soaked in a cobalt salt solution of divalent cobalt strong electrolyte at 90°C for 18 hours. 2. In step (2), Co... x The ratio of the surface area of ​​Ti4O9 / Ti to the volume of the mixed liquid in the reactor is 1.5 cm². 2 35 mL, and the reaction vessel was kept at 80°C for 8 hours. 3. In step (3), graphene oxide was coated onto the surface of the cobalt titanate nanowire network using an electrodeposition method, and the deposition time was set to 40 s. All other steps and parameters were the same as in Example 1.

[0077] Figure 11 40-GO / Co3O4 / Co x SEM images of Ti4O9 / Ti show that graphene oxide does not completely cover the nanowire network.

[0078] Figure 12 For 1 mol L -1 The LSV curve in KOH shows that an overpotential of 312 mV can reach 10 mA cm⁻¹. -2 The current density.

[0079] Figure 13 To obtain the LSV curve in alkaline seawater, an overpotential of 288 mV is required to reach 10 mA cm⁻¹. -2 Although the overpotential of the graphene oxide is lower at low currents compared to alkaline pure water electrolytes, its overpotential at high currents is significantly higher. This is because the graphene oxide coverage is not high, resulting in limited protection of the active ingredients and reducing its electrocatalytic effect in seawater.

[0080] Example 3

[0081] Electrodeposition of 160 s of graphene oxide / cobalt tetroxide / cobalt titanate / titanium (160-GO / Co3O4 / Co) xPreparation, characterization and performance testing of Ti4O9 / Ti

[0082] The difference from Example 1 is: 1. The alkaline solution in step (1) is 10 mL / L. -1 NaOH solution was used to soak the titanium foam in 85°C for 7 hours, and the foamed titanium was then soaked in a cobalt salt solution containing divalent cobalt strong electrolyte at 85°C for 15 hours. 2. In step (2), Co... x The ratio of the area of ​​Ti4O9 / Ti to the volume of the mixed liquid in the reactor is 2 cm². 2 35 mL, the reaction vessel was reacted at 80℃ for 10 hours. 3. In step (3), graphene oxide was coated onto the surface of the cobalt titanate nanowire network using an electrodeposition method, and the deposition time was set to 160 s. All other steps and parameters were the same as in Example 1.

[0083] Figure 14 160-GO / Co3O4 / Co x SEM images of Ti4O9 / Ti show that the nanowire network is completely covered by graphene oxide.

[0084] Figure 15 For 1 mol L -1 The LSV curve in KOH shows that an overpotential of 342 mV can reach 10 mA cm⁻¹. -2 The current density.

[0085] Figure 16 To obtain the LSV curve in alkaline seawater, an overpotential of 369 mV is required to reach 10 mA cm⁻¹. -2 The current density of the electrolyte was significantly higher than that of alkaline pure water electrolyte, resulting in a significantly increased overpotential. This is because the graphene oxide coating was too thick, hindering sufficient contact between the active ingredients and the electrolyte, thus affecting the electrocatalytic effect.

[0086] Example 4

[0087] Graphene oxide / cobalt tetroxide / cobalt titanate / titanium (GO / 0.1-Co3O4 / Co) prepared with low cobalt nitrate concentration x Preparation and performance testing of Ti4O9 / Ti

[0088] All steps and parameters are the same as in Example 1, the only difference being that in step (1), 0.3g Co(NO3)2·6H2O is replaced with 0.1g Co(NO3)2·6H2O, and the mass-volume ratio of Co(NO3)2·6H2O to the mixed solvent is 0.1g:30mL. Due to the low concentration of cobalt nitrate, the Co3O4 content grown after hydrothermal treatment is too low, resulting in a low 0.1-Co3O4 / Co content. x Ti4O9 / Ti in 1 mol L -1The OER catalytic performance of KOH is not high, such as Figure 17 As shown, further GO deposition did not significantly alter the OER catalytic performance, with no marked improvement or decrease.

[0089] Example 5

[0090] Graphene oxide / cobalt tetroxide / cobalt titanate / titanium (GO / 0.5-Co3O4 / Co) prepared with high cobalt nitrate concentration x Preparation and performance testing of Ti4O9 / Ti

[0091] All steps and parameters are the same as in Example 1, the only difference being that in step (1), 0.3g Co(NO3)2·6H2O is replaced with 0.5g Co(NO3)2·6H2O, and the mass-volume ratio of Co(NO3)2·6H2O to the mixed solvent is 0.5g:30mL. Due to the increased cobalt nitrate concentration, the Co3O4 grown after hydrothermal treatment exhibits aggregation, resulting in the obtained 0.5-Co3O4 / Co x Ti4O9 / Ti in 1 mol L -1 The OER catalytic performance of KOH decreased compared to the optimal sample, such as... Figure 18 As shown, further GO deposition did not significantly alter the OER catalytic performance, with no marked improvement or decrease.

[0092] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A titanium-based self-supporting anode catalyst for seawater electrolysis, characterized in that: It consists of a cobalt titanate nanowire network grown on foamed titanium, cobalt tetroxide nanoparticles dispersed in the nanowire network, and graphene oxide covering the surface of the nanowire network.

2. The titanium-based self-supporting anode catalyst for seawater electrolysis according to claim 1, characterized in that: The cobalt titanate nanowires have a diameter of 30-50 nm, the cobalt tetroxide nanoparticles have a size of 20-50 nm, and the graphene oxide on the surface of the nanowire network is a single layer.

3. A method for preparing a titanium-based self-supporting anode catalyst for seawater electrolysis, characterized in that... Includes the following steps: (1) In-situ growth of cobalt titanate nanowire network on the surface of titanium foam First, the foamed titanium is soaked in an alkaline solution and then washed with deionized water until the washing solution is neutral. It is then vacuum dried for later use. Next, the treated foamed titanium is soaked in a cobalt salt solution to complete ion exchange, washed with deionized water, and vacuum dried to obtain a cobalt titanate nanowire network / foamed titanium. (2) Growth of cobalt tetroxide nanoparticles within a cobalt titanate nanowire network First, Co(NO3)2·6H2O is dissolved in a mixed solvent composed of ethanol and deionized water to form a cobalt nitrate solution; then, ammonia water is added while stirring, and the cobalt nitrate solution with added ammonia water is transferred to a reaction vessel lined with polytetrafluoroethylene. The cobalt titanate nanowire network / foam titanium obtained in step (1) is placed in a reaction vessel, sealed, and reacted at 80°C to grow cobalt tetroxide nanoparticles in the cobalt titanate nanowire network, thus obtaining cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foam titanium; finally, the cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foam titanium is taken out, thoroughly washed with deionized water, and vacuum dried for later use. (3) Coating the surface of the cobalt titanate nanowire network with graphene oxide Using the dried cobalt tetroxide nanoparticles / cobalt titanate nanowire network / foam titanium obtained in step (2) as the working electrode, Ag / AgCl electrode as the reference electrode, carbon rod as the counter electrode, and graphene oxide dispersion as the electrolyte, constant potential deposition was performed to cover the surface of the nanowire network with a single layer of graphene oxide.

4. The preparation method according to claim 3, characterized in that: The alkaline solution in step (1) is 10 mL / L. -1 KOH or NaOH solution.

5. The preparation method according to claim 3, characterized in that: In step (1), the foamed titanium is soaked in alkaline solution at 80-90℃ for 6-8 hours, and the foamed titanium is soaked in cobalt salt solution at 80-90℃ for 12-18 hours.

6. The preparation method of the titanium-based self-supporting electrolytic seawater anode catalyst according to claim 3, characterized in that: The cobalt salt solution in step (1) is a divalent cobalt strong electrolyte solution.

7. The preparation method of the titanium-based self-supporting electrolytic seawater anode catalyst according to claim 6, characterized in that: The divalent cobalt strong electrolyte solution is a Co(NO3)2·6H2O solution.

8. The preparation method according to claim 3, characterized in that: In step (2), the mass-to-volume ratio of Co(NO3)2·6H2O to the mixed solvent is (0.1–0.5 g):(30 mL), the volume ratio of ammonia to cobalt nitrate solution is 1:6, and the ratio of the area of ​​the cobalt titanate nanowire network / foam titanium to the volume of the mixed liquid in the reactor is (1–2 cm²). 2 ):(35mL), cobalt titanate nanowire network / foam titanium was placed in the reaction vessel and sealed, and reacted at 80℃ for 8-12h.

9. The preparation method according to claim 3, characterized in that: The graphene oxide dispersion in step (3) consists of monolayer graphene oxide dispersed in deionized water at a mass concentration of 0.5 mg / mL. -1 This is the optimal solution.

10. The preparation method according to claim 3, characterized in that: The deposition potential during constant potential deposition in step (3) is -1.1V (vs.Ag / AgCl), and the deposition time is 40-160s.

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