Anionic covalent grafted metal catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electrochemistry, and particularly relates to a metal catalyst with the surface grafted with anion groups and a preparation method and application of the metal catalyst. The catalyst is formed by grafting small organic molecules with anion groups on the basis of an existing metal catalyst. Hydroxyl adsorbed on the surface of a metal catalyst is used as an active site and is covalently bound with organic molecules through chemical bonds, and anion groups are anchored on the surface in a strong bonding manner, so that the bonding strength of the anion groups and the catalyst is enhanced, and the anion groups are prevented from falling off and losing; besides, after the anionic groups are grafted, the potential of the surfaces of the catalyst nanoparticles is increased compared with that before, sedimentation and agglomeration of the catalyst nanoparticles in the process of preparing catalyst slurry are slowed down, and preparation and production of industrial-grade catalyst slurry and membrane electrodes are facilitated. The invention provides a feasible way for reasonable design and successful preparation of the anion modified catalyst, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical catalysis, and in particular relates to a metal catalyst with anionic groups grafted onto its surface, a preparation method and an application thereof. Background Art

[0002] As a zero-carbon energy carrier, hydrogen is a key path to achieving carbon neutrality. Green hydrogen (produced through water electrolysis using renewable energy) has become a key alternative to fossil fuel-based hydrogen (grey and blue hydrogen) due to its zero-carbon emissions. With the large-scale deployment of fluctuating renewable energy sources such as wind power and photovoltaics, water electrolysis can serve as a flexible "electricity-to-hydrogen" conversion technology, addressing renewable energy curtailment and achieving energy allocation across time and space.

[0003] Traditional alkaline water electrolysis (AWE) relies on liquid electrolytes (such as KOH solution), which has the disadvantages of large equipment size, low efficiency (~60%), slow start-up, and low current density (usually <0.5A / cm 2 ), it is difficult to match with fluctuating power sources, and it is prone to corrosion and gas crossover problems. In addition, the porous diaphragm easily leads to hydrogen and oxygen mixing, which poses an explosion risk and requires additional purification steps. The challenge of high-temperature solid oxide water electrolysis (SOEC) is that high temperature (700-1000°C) operation leads to accelerated material degradation, complex systems, and limited applicable scenarios. Therefore, solid polymer membrane water electrolysis technology has become the current research hotspot and key breakthrough direction.

[0004] Solid polymer membrane electrolysis water technology is usually referred to as proton exchange membrane electrolysis water (PEMWE). PEMWE has high proton conductivity (such as perfluorosulfonic acid membrane) and can be used at high current density (>2A / cm 2 ) operating under the same conditions, achieving efficiencies of 70-80%. Its extremely fast response makes it suitable for direct coupling with wind and solar power generation. The hydrogen outlet pressure of the water electrolysis device can reach 3-6 MPa, reducing compression energy consumption. The gas purity is >99.99%, eliminating the need for additional separation. PEMWE boasts a high volumetric power density, making it suitable for distributed hydrogen production scenarios (such as hydrogen refueling stations).

[0005] Solid polymer membrane water electrolysis technology still faces key challenges. One bottleneck is its dependence on precious metals: the anodic oxygen evolution reaction (OER) requires an iridium-based catalyst (IrO2), a scarce global resource (annual production of approximately 7 tons). Catalyst costs account for 30-40% of the total system cost. Furthermore, the membrane electrode interface (MEI) presents high contact resistance between the electrode and membrane, impacting overall efficiency.

[0006] To overcome the above challenges, this patent promotes proton dissociation and improves catalytic activity by grafting anionic groups on the catalyst surface in the form of covalent bonds. Summary of the Invention

[0007] The first object of the present invention is to provide a metal catalyst with anionic groups grafted on its surface and a preparation method thereof, the activity and stability of which can meet the industrial requirements of PEM water electrolysis and help enhance the proton dissociation and transfer process.

[0008] The second object of the present invention is to provide an oxygen evolution reaction catalyst electrode, a preparation method thereof, and a water electrolysis device, which uses a catalyst with surface grafted anionic groups to accelerate the OER kinetics.

[0009] The metal catalyst with anionic groups grafted on the surface provided by the present invention is composed of an organic small molecule with anionic groups grafted on the basis of an existing metal catalyst (including commercial catalysts or laboratory self-synthesized catalysts);

[0010] The metal catalyst is a noble metal and its oxide, transition metal and its oxide, sulfide, nitride, carbide and hydroxide, rare earth metal and its perovskite structure, as well as the above-mentioned multi-metal oxides and multi-metal alloys; the hydroxyl groups adsorbed on the surface of the metal catalyst are used as active sites, and are covalently bonded to the organic molecules through chemical bonds, and the anionic groups are anchored to the surface by a "strong bond" method, thereby enhancing the binding strength between the anionic groups and the catalyst and preventing the anionic groups from falling off and losing. The anchored anionic groups help to enhance the proton dissociation and transfer process, thereby accelerating the reaction kinetics. In addition, after the anionic groups are grafted, the potential on the surface of the catalyst nanoparticles is higher than before, which slows down their sedimentation and agglomeration during the preparation of the catalyst slurry, which is beneficial to the preparation and production of industrial-grade catalyst slurries and membrane electrodes.

[0011] Optionally, the noble metal is selected from Ir, Ru, Pt, Rh, Pd, Os, etc., the transition metal is selected from Fe, Co, Ni, Mn, Cu, Mo, W, etc., and the rare earth metal is La.

[0012] Optionally, the organic small molecule is selected from halosulfonic acid, sodium bromomethylsulfonate, sodium bromoethylsulfonate, sodium bromopropylsulfonate, 4-bromo-1-butanesulfonic acid, trifluoromethanesulfonic acid, sodium chloromethylsulfonate, sodium 2-chloroethylsulfonate, sodium 3-chloro-2-hydroxypropanesulfonate, sodium 3-hydroxy-1-propanesulfonate, sodium allylsulfonate, 1,3-propane sultone, 1,4-butane sultone, sodium 2-bromoethanesulfonate, 3-aminopropyltriethoxysilane, sulfonated aminopropyltriethoxysilane, chloromethylphosphoric acid, 2-bromoethylphosphoric acid, One of vinyl phosphoric acid, (3-bromopropyl)phosphonic acid, acrylic acid, 4-bromo-n-butyric acid, 3-bromopropionic acid, bromoacetic acid, tetramethyltetravinylcyclotetrasiloxane, 1-vinylimidazole, 1,4-dioxane, 2-aminoethanethiol hydrochloride, pentafluorostyrene, epoxypropyl phenyl ether, 1H,1H,2H-perfluoro-1-octene, perfluoro(4-methyl-3,6-dioxa-7-octene)sulfonyl fluoride, 1H,1H,2H,2H-perfluorodecanethiol, 3-mercapto-1-propanesulfonic acid sodium salt, etc.

[0013] The present invention also provides a method for preparing the metal catalyst having anionic groups grafted onto its surface, which comprises the following steps:

[0014] (1) Ultrasonic dispersion and dissolution of the catalyst and organic small molecules in an organic solvent in a certain ratio;

[0015] (2) heating the mixed solution according to preset conditions and heating it for a certain period of time under stirring conditions;

[0016] (3) After the reaction is completed, the mixed solution is cooled to room temperature, filtered, washed, and vacuum dried;

[0017] (4) placing the product in a dilute sulfuric acid solution and performing an acidification treatment at a certain temperature for a period of time;

[0018] (5) After the acidification is completed, the mixed solution is cooled to room temperature, filtered, washed, and vacuum dried to obtain the finished product.

[0019] Optionally, in step (1), the mass ratio of the metal catalyst to the organic small molecule is 1:(0.1-5), preferably 1:(3-5).

[0020] The organic solvent is selected from anhydrous ethanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methyl isobutyl ketone, tetrahydrofuran, toluene, and ionic liquids (1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium nitrate, ethylammonium nitrate, trimethylammonium formate, and 1-butylpyridinium tetrafluoroborate);

[0021] Optionally, in step (2), the heating conditions are: controlling the heating rate to 1°C / min to 20°C / min, heating to 80°C to 150°C, and reacting for 1h to 48h;

[0022] Optionally, in steps (3) and (5), the detergent used for washing is selected from anhydrous ethanol, deionized water, isopropyl alcohol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, and toluene; and the vacuum drying temperature is room temperature to 80°C;

[0023] Optionally, in step (4), the concentration of the dilute sulfuric acid is 0.05M to 1M, the acid treatment temperature is room temperature to 80°C, and the treatment time is 0.1h to 12h;

[0024] The present invention also provides the use of the catalyst with anionic groups grafted onto its surface in the preparation of a catalytic electrode for oxygen evolution reaction.

[0025] The catalytic electrode comprises an electrode carrier and a catalyst with surface-grafted anionic groups covering the electrode carrier.

[0026] The electrode carrier is a conductive substrate or a proton exchange membrane; the conductive substrate is one of carbon felt, carbon film, carbon cloth, titanium felt, metal foam or metal foil; the proton exchange membrane is one of perfluorosulfonic acid resin film, sulfonated polyvinylidene fluoride membrane, sulfonated polysulfone membrane, sulfonated polyetheretherketone membrane, sulfonated polyaryletherketone membrane, phosphoric acid-doped polybenzimidazole membrane, and a composite membrane of the above resin film and organic or inorganic fillers.

[0027] The preparation method of the oxygen evolution reaction catalyst electrode comprises the following specific steps:

[0028] (1) adding the catalyst having the surface grafted anionic groups, a binder, and a conductive agent into a solvent to form a catalyst slurry;

[0029] (2) The catalyst slurry is coated on a conductive substrate or a proton exchange membrane after ball milling, mechanical stirring, and ultrasonic dispersion to form an oxygen evolution reaction catalyst electrode. Alternatively, the catalyst slurry is first sprayed on a carrier film (such as a polytetrafluoroethylene film), and then adhered to the proton exchange membrane after drying, and the carrier film is peeled off to obtain an oxygen evolution reaction catalyst electrode.

[0030] The proportion of the binder in the catalyst slurry is 0.1% to 40%, the proportion of the conductive agent in the catalyst slurry is 1 to 30%, and the loading amount of the catalyst with surface grafted anionic groups on the oxygen evolution reaction catalyst electrode is 0.1 mg / cm 2 ~30mg / cm 2The solvent is selected from a mixture of one or more of deionized water, methanol, anhydrous ethanol, isopropanol, tetrahydrofuran, acetone, dimethyl sulfoxide, and n-hexanol; the binder is one of a perfluorosulfonic acid polymer membrane solution and a sulfonated resin membrane solution, and the conductive agent is selected from one of carbon nanotubes, carbon black, and graphene.

[0031] The present invention also provides a water electrolysis device, wherein the catalyst having the surface-grafted anionic groups as described in the present invention is an anode catalyst; or, the water electrolysis device has the oxygen evolution reaction catalyst electrode as described in the present invention.

[0032] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0033] (1) The present invention proposes a "strong bonding" strategy to achieve a firm anchoring of the anionic groups on the catalyst surface in the form of covalent bonds, thereby preventing them from falling off and losing.

[0034] (2) The anionic groups grafted onto the catalyst surface enhance the proton transfer process and promote the formation of *OOH intermediates, thereby accelerating the OER kinetics. In addition, the stable modification of the anionic groups ensures the durability of the anionic grafted catalyst during the OER process.

[0035] (3) In addition, since the surface of the catalyst carries more negative charges after the anionic groups are grafted onto the surface, the repulsive force between the catalyst nanoparticles in the catalyst slurry is enhanced, making it difficult for the catalyst particles to precipitate and agglomerate in a suitable catalyst slurry, which facilitates the preparation of industrial-grade catalyst slurries and membrane electrodes and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the Ir / IrO of Example 1 of the present invention x Schematic diagram of the synthesis steps of ~SO3H catalyst.

[0037] Figure 2 Schematic diagram of a PEM water electrolysis hydrogen production device according to an embodiment of the present invention.

[0038] Figure 3 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x Fourier transform infrared spectrum.

[0039] Figure 4 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x X-ray photoelectron spectrum.

[0040] Figure 5is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x Energy dispersive spectrum diagram.

[0041] Figure 6 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x X-ray diffraction spectrum of .

[0042] Figure 7 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x Transmission electron micrograph of .

[0043] Figure 8 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x LSV curve of quasi-membrane electrode assembly test and quasi-membrane electrode test device.

[0044] Figure 9 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x CV curves tested in a three-electrode setup.

[0045] Figure 10 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x Current density and potential curves during CV cycling, with 10,000 CV cycles scanned between 0.95 and 1.65 V at a scan rate of 50 mV s -1 .

[0046] Figure 11 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x EIS spectrum and corresponding equivalent circuit diagram tested in a three-electrode system.

[0047] Figure 12 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x The membrane electrode made of the catalyst is assembled in a water electrolysis hydrogen production device, and the polarization curve is obtained by recording the electrolytic cell voltage at different current densities.

[0048] Figure 13 is the Ir / IrO of the embodiment of the present invention x~ Electrical stability curve of SO3H-PEMWE during 1000 hours of constant current test.

[0049] Figure 14 is the Ir / IrO of the embodiment of the present invention x The chemical structure of the SO3H catalyst did not change before and after OER treatment, as analyzed by FTIR and XPS.

[0050] Figure 15 is the Ir / IrO of the embodiment of the present invention x ~SO3H and control sample Ir / IrO x The aggregation behavior of the nanostructured particles in solvents was studied by zeta electrophoresis and dynamic light scattering spectroscopy.

[0051] Figure 16 is the Ir / IrO of the embodiment of the present invention x Schematic diagram of preparing suitable catalyst slurry with SO3H and realizing the production of large-area membrane electrodes.

[0052] Figure 17 The embodiment of the present invention is Ir / IrO x -H2PO3 catalyst, Ir / IrO x -COOH catalyst, Ir / IrO x -NH2 catalyst and Ir / IrO x Schematic diagram of the synthesis steps of -SO3H-Ar catalyst. DETAILED DESCRIPTION

[0053] The present invention is further described below through embodiments in conjunction with the accompanying drawings.

[0054] The embodiment provides a catalyst with surface grafted anionic groups, the material of which is abbreviated as M~A, specifically including a catalyst body and a small molecule with specific anionic groups grafted on the surface, the catalyst body is a precious metal or non-precious metal catalyst M that is stable under strong acid and strong oxidizing conditions, and the small molecule A with specific anionic groups grafted on the surface.

[0055] In the catalyst M~A with surface-grafted anionic groups, M provides catalytic active sites, and the anionic groups on A can promote the dissociation of water bound to the active sites of M, enhance proton conduction between the catalyst and the ionomer interface, and thus accelerate the reaction kinetics.

[0056] Example 1, Ir / IrO x -SO3H catalyst and preparation method thereof.

[0057] This embodiment discloses an Ir / IrO x -SO3H catalyst, the metal oxide catalyst is commercial iridium oxide Ir / IrO xThe grafted small molecule raw material is 1,3-propane sultone, which is grafted through Ir / IrO x Nucleophilic substitution reaction between surface hydroxyl groups and 1,3-propanesulfonic acid for efficient one-step synthesis of Ir / IrO x ~SO3H catalyst, achieving the strong anchoring of -SO3H to Ir / IrO x surface.

[0058] Ir / IrO x The preparation method of the -SO3H catalyst specifically comprises the following steps:

[0059] like Figure 1 As shown, first weigh 100 mg of Ir / IrO x Add 12 ml of toluene into a round-bottom flask and disperse it evenly with ultrasound. Then add 50 mg of 1,3-propane sultone and continue to disperse it with ultrasound until it is completely dissolved. Then, heat the round-bottom flask to 110°C at a heating rate of 10°C / min and react for 24 hours under stirring. After the reaction is completed, filter and separate the solid product, wash it three times with anhydrous ethanol and deionized water respectively, and then dry it in a vacuum oven at 60°C overnight.

[0060] The dried product was acidified with 0.5 M dilute sulfuric acid at 60 °C for 1 h, and washed again with anhydrous ethanol and deionized water three times. The solid product was then dried in a vacuum oven at 60 °C overnight to obtain the final product Ir / IrO x -SO3H.

[0061] This embodiment also provides an electrode, which is composed of a conductive substrate and a catalyst layer covering the conductive substrate, wherein the catalyst layer contains Ir / IrO x ~SO3H catalyst; the conductive substrate is a perfluorosulfonic acid resin film and a glassy carbon electrode, the perfluorosulfonic acid resin film is 50 to 127 μm, and the glassy carbon electrode area is 0.0706 cm -2 The catalyst loading on the perfluorosulfonic acid resin film is 1 to 2 mg / cm 2 The catalyst loading on the glassy carbon electrode was 22.5 μg cm -2 .

[0062] This embodiment also provides a method for preparing an electrode, comprising the following steps:

[0063] 20 mg of catalyst and 120 μL of 5 wt.% perfluorosulfonic acid resin membrane solution were added to 10 mL of a mixed solvent of isopropanol and water, wherein the volume ratio of ethanol to water was 5:1, and after ultrasonic dispersion, a catalyst slurry was formed; the prepared catalyst slurry was ultrasonically sprayed on a perfluorosulfonic acid resin film, and a membrane electrode was obtained after hot pressing; 5 mg of catalyst, 2 mg of carbon powder and 20 μL of 5 wt.% perfluorosulfonic acid resin membrane solution were added to 1 mL of a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water was 5:1, and after ultrasonic dispersion, a catalyst slurry was formed; the catalyst slurry was drop-coated on a glassy carbon electrode, and an OER catalyst electrode was obtained after drying.

[0064] The present invention also provides a PEM water electrolysis hydrogen production device (PEMWE). Figure 2 As shown, the OER catalyst electrode is assembled between two fixtures with a flow field and assembled with a certain pressure. Ultrapure water at 80°C is circulated at the anode, and a certain current is applied to the anode and cathode to electrolyze water to produce hydrogen.

[0065] In this example, the structure and electrochemical properties of the catalyst after the surface grafting of anionic groups were characterized by using currently commonly used analytical methods such as X-ray diffraction (XRD), projection electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), etc.

[0066] The surface structure of the catalyst material was analyzed using FTIR. Figure 3 As shown, Ir / IrO x ~SO3H and Ir / IrO x At 3430cm -1 and 1629cm -1 Typical OH stretching and bending vibration peaks are shown. x ~SO3H and Ir / IrO x At 540cm -1 The Ir-O stretching vibration peaks near the Ir / IrO x The stretching vibration of -SO3H group in SO3H is between 1213 and 1000 cm -1 New characteristic bands appeared in the range, indicating that Ir / IrO x The surface was functionalized with -SO3H.

[0067] Study of Ir / IrO by XPS x ~The element content and electronic structure of SO3H catalyst. Figure 4 As shown, compared with commercial Ir / IrO xXPS spectrum shows Ir / IrO x The S2p signal at 168.1eV in the XPS spectrum of SO3H. Ir / IrO x The high-resolution S2p spectrum of ~SO3H is decomposed into two orbital splitting peaks, which are respectively assigned to the S2p in -SO3H. 3 / 2 (167.8eV) and S2p 1 / 2 (169.0eV), and XPS spectroscopy further proved that -SO3H was successfully grafted onto Ir / IrO x superior.

[0068] EDS element mapping intuitively reveals the presence and uniform distribution of S element on the surface of Ir / IrO catalyst, such as Figure 5 As shown, it further verifies that Ir / IrO x ~Successful synthesis of SO3 catalyst.

[0069] XRD results (such as Figure 6 As shown) shows, Ir / IrO x The samples did not undergo phase change before and after -SO3H modification. Figure 7 (shown) for Ir / IrO x ~SO3H and Ir / IrO x The morphology of the catalysts was characterized, and it was found that the microstructures of the two were similar, both of which were clusters of irregular nanoparticles and rough surfaces. The characterization results showed that the morphology of the catalyst was not affected after grafting -SO3H.

[0070] In this example, the electrochemical characterization methods such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to study the Ir / IrO x The electrochemical performance of Ir / IrO was investigated by using a quasi-membrane electrode assembly method. x ~SO3H and Ir / IrO x The LSV curve of the catalyst was characterized. The membrane electrode was subjected to linear voltammetry scanning in a 0.5M H2SO4 electrolyte solution at 80°C to obtain its LSV curve, as shown in FIG. Figure 8 As shown, at high current density, Ir / IrO x The catalytic performance of SO3H catalyst is significantly better than that of Ir / IrO x catalyst.

[0071] A three-electrode system was used to investigate the Ir / IrO x ~SO3H and Ir / IrO xThe CV curves of the catalysts were studied. The anodic peak in the range of 0.85–1.14 V (vs. RHE) was assigned to Ir 3+ Oxidized to Ir 4+ ( Figure 9 ) and Ir / IrO x In comparison, due to the introduction of -SO3H, Ir / IrO x The anodic potential of -SO3H shows a negative shift, indicating that the -SO3H group enhances the electron transfer process. x The OER current density (vs. RHE) of SO3H at 1.672 V increases slightly with the increase of cycle number and is greater than that of Ir / IrO at each cycle number. x OER current density ( Figure 10 ), proving the promoting effect of -SO3H on catalytic activity.

[0072] EIS and equivalent circuit model simulations are as follows Figure 11 As shown in Table 1, it shows that Ir / IrO x ~ Charge transfer resistance (R ct ) significantly reduced (76.4Ωvs.Ir / IrO x The EIS data show that -SO3H grafting effectively improves the electrical conductivity and charge-mass transfer capability, thereby accelerating the OER kinetics.

[0073] In the actual working environment, it was further verified that the membrane electrode was assembled in the water electrolysis hydrogen production device, and the polarization curve (such as Figure 12 b). At a current density of 3 A / cm 2 When, Ir / IrO x The voltage of SO3H-PEMWE is 1.75V, which is higher than Ir / IrO x -PEMWE voltage is 125mV lower, which is better than the 2026 US DOE target (1.8V@3Acm -2 ) performance requirements, Figure 12 a is Ir / IrO x Schematic diagram of the surface OER mechanism of ~SO3H.

[0074] Long-term stability is an essential criterion for measuring catalyst performance and validating “strong bonding” strategies, e.g. Figure 13 As shown, Ir / IrO x During the 1000-hour constant current test, the voltage of SO3H-PEMWE did not show a significant increase, indicating that Ir / IrO x ~SO3H electrode has extremely high stability.

[0075] After OER treatment, Ir / IrO was analyzed by FTIR and XPS. x The chemical structure of -SO3H. The -SO3H group persists and maintains its original chemical state (e.g. Figure 14 After OER treatment, the S content in Ir / IrOx~SO3H remained unchanged as determined by XPS (Table 2), thus verifying the x The structural and chemical stability of ~SO3H and the feasibility of the "strong bond" strategy.

[0076] The Ir / IrO x Agglomeration behavior of -SO3H catalyst in solvent. After grafting -SO3H group, Ir / IrO x The ζ-potential of the catalyst shifted from -13 mV to -30 mV ( Figure 15 As shown), further indicating that Ir / IrO x The successful synthesis of SO3H and Ir / IrO x The dispersibility of the SO3H catalyst in the solvent is enhanced.

[0077] Given that Ir / IrO x ~SO3H catalyst is not easy to settle, suitable catalyst slurry was prepared, and the production of large-area membrane electrode was realized, such as Figure 16 shown.

[0078] Example 2, Ir / IrO x -H2PO3 catalyst and preparation method thereof.

[0079] This embodiment discloses an Ir / IrO x -H2PO3 catalyst, the metal oxide catalyst is commercial iridium oxide Ir / IrO x The grafted small molecule raw material is 2-bromoethyl phosphate, which is grafted through Ir / IrO x Nucleophilic substitution reaction between surface hydroxyl groups and 2-bromoethylphosphoric acid resulted in efficient one-step synthesis of Ir / IrO x -H2PO3 catalyst, to achieve the strong anchoring of -H2PO3 to Ir / IrO x surface.

[0080] Ir / IrO x -H2PO3 catalyst preparation method, specifically comprising the following steps:

[0081] like Figure 17 As shown in a, first weigh 100 mg of Ir / IrO xAdd to a round-bottom flask containing 12 ml of DMF and ultrasonically disperse evenly, then add 70 mg of K2CO3 and continue ultrasonically dispersing until completely dissolved; then heat the round-bottom flask to 80°C at a heating rate of 10°C / min, stir for 30 minutes, add 77.47 mg of 2-bromoethylphosphoric acid, maintain heating at 80°C, continue stirring and react for 12 hours. After the reaction is completed, filter and separate the solid product, wash three times with anhydrous ethanol and deionized water respectively, and then place the solid product in a vacuum oven at 60°C to dry overnight.

[0082] The dried product was acidified with 0.5 M dilute sulfuric acid at 60 °C for 1 h, and washed again with anhydrous ethanol and deionized water three times. The solid product was then dried in a vacuum oven at 60 °C overnight to obtain the final product Ir / IrO x -H2PO3.

[0083] This example uses the electrode preparation method and water electrolysis hydrogen production device described in Example 1. At a current density of 1 A / cm 2 When, Ir / IrO x -H2PO3-PEMWE has a voltage of 1.54V, which is lower than that of Ir / IrO x -PEMWE voltage (1.64V@1A / cm 2 ) is 100mV lower, see Table 3.

[0084] Example 3, Ir / IrO x -COOH catalyst and preparation method thereof.

[0085] This embodiment discloses an Ir / IrO x -COOH catalyst, the metal oxide catalyst is commercial iridium oxide Ir / IrO x The grafted small molecule raw material is 3-bromopropionic acid, through Ir / IrO x The nucleophilic substitution reaction between the surface hydroxyl groups and 3-bromopropionic acid efficiently synthesized Ir / IrO in one step. x -COOH catalyst, to achieve a firm anchoring of -COOH to Ir / IrO x surface.

[0086] Ir / IrO x The preparation method of the -COOH catalyst specifically comprises the following steps:

[0087] like Figure 17 As shown in b, first weigh 100 mg of Ir / IrO xAdd to a round-bottom flask containing 12 ml of DMF and ultrasonically disperse evenly, then add 70 mg of K2CO3 and continue ultrasonically dispersing until completely dissolved; then heat the round-bottom flask to 80°C at a heating rate of 10°C / min, stir for 30 minutes, add 62.73 mg of 3-bromopropionic acid, maintain heating at 80°C, continue stirring and react for 12 hours, after the reaction is completed, filter and separate the solid product, wash three times with anhydrous ethanol and deionized water respectively, and then place the solid product in a vacuum oven at 60°C to dry overnight.

[0088] The dried product was acidified with 0.5 M dilute sulfuric acid at 60 °C for 1 h, and washed again with anhydrous ethanol and deionized water three times. The solid product was then dried in a vacuum oven at 60 °C overnight to obtain the final product Ir / IrO x -COOH.

[0089] This example uses the electrode preparation method and water electrolysis hydrogen production device described in Example 1. At a current density of 1 A / cm 2 When, Ir / IrO x The voltage of -COOH-PEMWE is 1.58 V, which is lower than that of Ir / IrO x -PEMWE voltage (1.64V@1A / cm 2 ) is 60mV lower, see Table 3.

[0090] Example 4, Ir / IrO x -NH2 catalyst and preparation method thereof.

[0091] This embodiment discloses an Ir / IrO x -NH2 catalyst, the metal oxide catalyst is commercial iridium oxide Ir / IrO x The grafted small molecule raw material is (3-aminopropyl) triethoxysilane, which is grafted through Ir / IrO x The nucleophilic substitution reaction between the surface hydroxyl groups and (3-aminopropyl)triethoxysilane resulted in the efficient synthesis of Ir / IrO in one step. x -NH2 catalyst, to achieve the strong anchoring of -NH2 to Ir / IrO x surface.

[0092] Ir / IrO x The preparation method of the -NH2 catalyst specifically comprises the following steps:

[0093] like Figure 17 As shown in c, first weigh 100 mg of Ir / IrO xAdd 12 ml of anhydrous ethanol into a round-bottom flask and disperse it evenly by ultrasonication. Then add 90.8 mg of (3-aminopropyl)triethoxysilane and continue to disperse it by ultrasonication until it is completely dissolved. Then, stir the round-bottom flask at room temperature for 24 hours. After the reaction is completed, filter and separate the solid product, wash it three times with anhydrous ethanol and deionized water respectively, and then dry it in a vacuum oven at 60°C overnight.

[0094] The dried product was acidified with 0.5 M dilute sulfuric acid at 60 °C for 1 h, and washed again with anhydrous ethanol and deionized water three times. The solid product was then dried in a vacuum oven at 60 °C overnight to obtain the final product Ir / IrO x -NH2.

[0095] This example uses the electrode preparation method and water electrolysis hydrogen production device described in Example 1. At a current density of 1 A / cm 2 When, Ir / IrO x The voltage of -NH2-PEMWE is 1.57V, which is higher than that of Ir / IrO x -PEMWE voltage (1.64V@1A / cm 2 ) is 70mV lower, see Table 3.

[0096] Example 5, Ir / IrO x -SO3H-Ar catalyst and preparation method thereof.

[0097] This embodiment discloses an Ir / IrO x -SO3H-Ar catalyst, the metal oxide catalyst is commercial iridium oxide Ir / IrO x The grafted small molecule raw material is epoxypropyl phenyl ether, through Ir / IrO x The nucleophilic substitution reaction between the surface hydroxyl groups and glycidyl phenyl ether resulted in the efficient synthesis of Ir / IrO in one step. x -SO3H-Ar catalyst, to achieve the strong anchoring of -SO3 to Ir / IrO x surface.

[0098] Ir / IrO x The preparation method of the -SO3H-Ar catalyst specifically comprises the following steps:

[0099] like Figure 17 As shown in d, first weigh 100 mg of Ir / IrO xAdd 12 ml of methyl isobutyl ketone (MIBK) into a round-bottom flask and disperse it evenly by ultrasonication. Then add 50 mg of SnCl2 and heat the round-bottom flask to 140 °C at a heating rate of 5 °C / min. After stirring for 30 minutes, add 61.5 mg of glycidyl phenyl ether and keep heating at 140 °C. Continue stirring and react for 24 hours. After the reaction is completed, filter and separate the solid product. Wash it three times with anhydrous ethanol and deionized water respectively. Then, dry the solid product in a vacuum oven at 60 °C overnight.

[0100] The solid product was placed in concentrated sulfuric acid and stirred at 110 °C for 6 h, filtered, washed and dried to obtain the final product Ir / IrO x -SO3H-Ar.

[0101] This example uses the electrode preparation method and water electrolysis hydrogen production device described in Example 1. At a current density of 1 A / cm 2 When, Ir / IrO x -SO3H-Ar-PEMWE has a voltage of 1.63 V, which is lower than that of Ir / IrO x -PEMWE voltage (1.64V@1A / cm 2 ) is 10mV lower, see Table 3.

[0102] Table 1

[0103] parameter <![CDATA[IrO2~SO3H]]> <![CDATA[IrO2]]> <![CDATA[R s (Oh)]]> 8.034 7.462 <![CDATA[R film (Oh)]]> 0.413 2.936 <![CDATA[CPE1.Q1(mMho s α-1 )]]> 8.150 0.957 <![CDATA[CPE1.α1]]> 0.554 0.496 <![CDATA[R ct (Oh)]]> 76.36 167.2 <![CDATA[CPE1.Q1(mMho s α-1 )]]> 7.185 4.623 <![CDATA[CPE1.α1]]> 0.886 0.832

[0104] Table 2

[0105]

[0106] Table 3

[0107] name Voltage <![CDATA[Ir / IrO x -PEMWE]]> <![CDATA[1.64V@1A / cm 2 ]]> <![CDATA[Ir / IrO x -H2PO3-PEMWE]]> <![CDATA[1.54V@1A / cm 2 ]]> <![CDATA[Ir / IrO x -COOH-PEMWE]]> <![CDATA[1.58V@1A / cm 2 ]]> <![CDATA[Ir / IrO x -NH2-ONE]]> <![CDATA[1.57V@1A / cm 2 ]]> <![CDATA[Ir / IrO x -SO3H-Ar-PEMWE]]> <![CDATA[1.63V@1A / cm 2 ]]> .

Claims

1. A metal catalyst with anionic groups grafted onto its surface, characterized in that: It is composed of small organic molecules with anionic groups grafted onto existing metal catalysts; The metal catalysts are noble metals and their oxides, transition metals and their oxides, sulfides, nitrides, carbides and hydroxides, rare earth metals and their perovskite structures, as well as the above-mentioned multi-metal oxides and multi-metal alloys; the hydroxyl groups adsorbed on the surface of the metal catalysts serve as active sites, covalently bonded to organic molecules through chemical bonds, and anchor the anionic groups to the surface through "strong bonding", thereby enhancing the bonding strength between the anionic groups and the catalyst and preventing the anionic groups from falling off and being lost.

2. The metal catalyst having anionic groups grafted onto its surface according to claim 1, characterized in that: The noble metal is selected from Ir, Ru, Pt, Rh, Pd, and Os; the transition metal is selected from Fe, Co, Ni, Mn, Cu, Mo, and W; and the rare earth metal is La.

3. The metal catalyst having anionic groups grafted onto its surface according to claim 2, characterized in that: The organic small molecule is selected from halosulfonic acid, sodium bromomethylsulfonate, sodium bromoethylsulfonate, sodium bromopropylsulfonate, 4-bromo-1-butanesulfonic acid, trifluoromethanesulfonic acid, sodium chloromethylsulfonate, sodium 2-chloroethylsulfonate, sodium 3-chloro-2-hydroxypropanesulfonate, sodium 3-hydroxy-1-propanesulfonate, sodium allylsulfonate, 1,3-propane sultone, 1,4-butane sultone, sodium 2-bromoethanesulfonate, 3-aminopropyltriethoxysilane, sulfonated aminopropyltriethoxysilane, chloromethylphosphonic acid, 2-bromoethylphosphonic acid, ethylene The invention further comprises one of the following: 1-amino-2-nitro-1-propanesulfonic acid, 2-amino-3-nitro-2-propanesulfonic acid, 2-amino-3 ...

4. The method for preparing a metal catalyst having anionic groups grafted onto its surface according to any one of claims 1 to 3, characterized in that: The specific steps are: (1) ultrasonically dispersing and dissolving the metal catalyst and the organic small molecule in an organic solvent to obtain a mixed solution; (2) heating the mixed solution under stirring conditions; (3) After the reaction is completed, the mixed solution is cooled to room temperature, filtered, washed, and vacuum dried to obtain the primary product; (4) placing the primary product in a dilute sulfuric acid solution for acidification; (5) After the acidification is completed, the mixed solution is cooled to room temperature, filtered, washed, and vacuum dried to obtain the finished product.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the metal catalyst to the organic small molecule in step (1) is 1:(0.1-5); The organic solvent is selected from anhydrous ethanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methyl isobutyl ketone, tetrahydrofuran, toluene, ionic liquid (1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium nitrate, ethylammonium nitrate, trimethylammonium formate, 1-butylpyridinium tetrafluoroborate; In step (2), the heating reaction conditions are: controlling the heating rate at 1°C / min to 20°C / min, heating to 80°C to 150°C, and reacting for 1h to 48h; In steps (3) and (5), the detergent used for washing is selected from anhydrous ethanol, deionized water, isopropyl alcohol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, and toluene; and the vacuum drying temperature is room temperature to 80°C; In step (4), the concentration of the dilute sulfuric acid is 0.05M to 1M, the acid treatment temperature is room temperature to 80°C, and the treatment time is 0.1h to 12h.

6. An oxygen evolution reaction catalytic electrode, characterized in that A metal catalyst comprising an electrode carrier and a surface-grafted anionic group-containing metal catalyst as claimed in any one of claims 1 to 4 covered on the electrode carrier; The electrode carrier is a conductive substrate or a proton exchange membrane; the conductive substrate is one of carbon felt, carbon film, carbon cloth, titanium felt, metal foam or metal foil; the proton exchange membrane is one of perfluorosulfonic acid resin film, sulfonated polyvinylidene fluoride membrane, sulfonated polysulfone membrane, sulfonated polyetheretherketone membrane, sulfonated polyaryletherketone membrane, phosphoric acid-doped polybenzimidazole membrane, and a composite membrane of the above resin film and organic or inorganic fillers.

7. The method for preparing an oxygen evolution reaction catalyst electrode according to claim 6, wherein: The specific steps are: (1) adding the metal catalyst with anionic groups grafted onto its surface, a binder, and a conductive agent into a solvent to form a catalyst slurry; (2) The catalyst slurry is coated on a conductive substrate or a proton exchange membrane after ball milling, mechanical stirring, and ultrasonic dispersion to form an oxygen evolution reaction catalyst electrode. Alternatively, the catalyst slurry is first sprayed on a carrier film, and after drying, it is attached to the proton exchange membrane, and the carrier film is peeled off to obtain the oxygen evolution reaction catalyst electrode.

8. The preparation method according to claim 7, characterized in that: The proportion of the binder in the catalyst slurry is 0.1% to 40%. The proportion of the conductive agent in the catalyst slurry is 1 to 30%; The loading amount of the catalyst with surface grafted anionic groups on the oxygen evolution reaction catalyst electrode is 0.1 mg / cm 2 ~30mg / cm 2 ; The solvent is selected from a mixture of one or more of deionized water, methanol, anhydrous ethanol, isopropanol, tetrahydrofuran, acetone, dimethyl sulfoxide, and n-hexanol; the binder is one of a perfluorosulfonic acid polymer membrane solution and a sulfonated resin membrane solution; and the conductive agent is selected from one of carbon nanotubes, carbon black, and graphene.

9. A water electrolysis device, characterized in that: The metal catalyst with anionic groups grafted onto the surface as claimed in any one of claims 1 to 4 is used as an anode catalyst; or the oxygen evolution reaction catalyst electrode as claimed in claim 6 is used.

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