A hydrogen fuel cell electrode catalyst, its preparation method and use

Abstract

This invention relates to the field of catalyst technology, and discloses a hydrogen fuel cell electrode catalyst, its preparation method, and its application. The hydrogen fuel cell electrode catalyst comprises a composite support and Pt particles supported on the composite support; the composite support comprises: graphene, a ZrO2 layer coated on the graphene, and a surface oxide layer bonded to the surface of the ZrO2 layer; the surface oxide layer is SiO2 and / or TiO2. The catalyst of this invention achieves high electrocatalytic efficiency when used in hydrogen fuel cell electrodes and exhibits good electrochemical stability, maintaining high electrocatalytic efficiency even in corrosive environments (such as phosphoric acid electrolytes).

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a hydrogen fuel cell electrode catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen fuel cells, with their advantages of zero emissions, high energy efficiency, rapid refueling, and renewable fuel, are becoming one of the key energy conversion technologies. In hydrogen fuel cells, the catalyst is the "first element" that efficiently and controllably converts chemical energy into electrical energy. Its activity and selectivity determine the rated efficiency and peak power of the fuel cell stack, while its stability and resistance to poisoning determine its lifespan and maintenance costs. Therefore, the catalyst is both a technological bottleneck in hydrogen fuel cells and a key lever for cost reduction and efficiency improvement.

[0003] From the perspective of electrode division of labor, the anode is responsible for the hydrogen oxidation reaction (HOR), which has extremely fast intrinsic kinetics. Typically, low-loaded platinum (Pt) or a small amount of alloyed Pt is sufficient. Engineering applications focus more on resistance to impurities such as carbon monoxide and sulfur, as well as the coordination between hydrogen supply purity and hydrothermal management. The cathode is responsible for the oxygen reduction reaction (ORR). Its multi-electron, multi-proton coupling pathway and high reaction free energy barrier make it a major bottleneck for efficiency and lifetime. Currently, various Pt-based catalysts and non-platinum group metals (Fe, Co, Ni) are commonly used. Noble metal Pt-based catalysts are the baseline for current industrial applications, but their high cost and resource scarcity make it difficult to meet long-term large-scale requirements. Furthermore, under extreme operating conditions, Pt still experiences activity degradation due to the coupling of dissolution / migration and support corrosion.

[0004] Patent CN119542445A discloses a topologically chiral semimetal catalyst for oxygen electrocatalysis, its preparation method, and its application. This topologically chiral semimetal catalyst is a supported catalyst, comprising a support, an active component, and a guest metal. The support is selected from Vulcan XC-72R, Vulcan XC-72, Ketjenblack, and carbon nanotubes. The active component is Pt, and the guest metal is selected from one or two of Ga, Al, Ba, Ge, Bi, Sb, Eu, Fe, Cr, Sr, and Mg. This topologically chiral semimetal catalyst exhibits high catalytic activity and product selectivity in the oxygen reduction reaction at the cathode of a fuel cell; however, the carbon support used results in poor electrochemical stability. Summary of the Invention

[0005] To address the technical problem of poor electrochemical stability in existing hydrogen fuel cell electrode catalysts, this invention provides a hydrogen fuel cell electrode catalyst, its preparation method, and its application. The catalyst of this invention achieves high electrocatalytic efficiency when used in hydrogen fuel cell electrodes and exhibits good electrochemical stability, maintaining high electrocatalytic efficiency even in corrosive environments (such as phosphoric acid electrolytes).

[0006] The specific technical solution of this invention is as follows:

[0007] In a first aspect, the present invention provides a hydrogen fuel cell electrode catalyst, comprising a composite support and Pt particles supported on the composite support; the composite support comprises: graphene, a ZrO2 layer coated on the graphene, and a surface oxide bonded to the surface of the ZrO2 layer; the surface oxide is SiO2 and / or TiO2.

[0008] ZrO2 can be firmly bonded to the graphene surface through CO-Zr bonds and physical anchoring. The two work together to produce the following effects: graphene can endow the composite support with good conductivity, enabling the catalyst to achieve high electrocatalytic efficiency when used in hydrogen fuel cell electrodes; ZrO2 has a robust crystal structure and can provide strong anchoring sites for Pt. These properties can alleviate the corrosion of graphene, and even if some graphene is corroded, ZrO2 can maintain the porous structure of the catalyst to a certain extent, preventing its collapse, thereby maintaining the dispersion and accessibility of active sites. In this way, the introduction of the ZrO2 layer can improve the electrochemical stability of the catalyst, enabling it to maintain high catalytic efficiency in corrosive environments (such as phosphoric acid electrolytes).

[0009] Based on this, by combining SiO2 and / or TiO2 on the surface of the ZrO2 layer, the electrochemical stability of the catalyst can be further improved. Specifically, the ZrO2-TiO2 interface can form a heterogeneous interface charge rearrangement, making the local electronic environment around the Pt active site more stable; the -SiOH group on the SiO2 surface and the Lewis acid site on the ZrO2 surface can form a complex acid-base environment, which can change the solvation and adsorption morphology of anions near the interface and reduce their tendency to form a dense blocking layer near the Pt active site.

[0010] Furthermore, compared to doping SiO2 and / or TiO2 into the ZrO2 layer, or first combining SiO2 and / or TiO2 on the graphene surface and then combining ZrO2, the present invention adopts the order of first combining ZrO2 and then combining SiO2 and / or TiO2, which can produce the following advantages: when ZrO2 is in the inner layer, its "strong anchoring" and "high structural stability" are mainly used to stabilize Pt and the framework, while TiO2 and / or SiO2 located on the catalyst surface can effectively regulate the adsorption of anions (such as phosphate ions), making it easier to achieve the optimal microenvironment for the cathodic oxygen reduction reaction (ORR) near Pt.

[0011] Secondly, the present invention provides a method for preparing the hydrogen fuel cell electrode catalyst, comprising:

[0012] S1: A ZrO2 layer is generated on the graphene surface through an in-situ reaction using a zirconium source;

[0013] S2: A surface oxide is generated on the surface of the product S1 by in-situ reaction with a surface oxide source, wherein the surface oxide source is a silicon source and / or a titanium source;

[0014] S3: Pt particles are generated on the surface of the S2 product through in-situ reaction with a platinum source.

[0015] Preferably, in step S1, the mass ratio of graphene to ZrO2 is 1:0.4~0.6, based on the assumption that the zirconium source has completely reacted.

[0016] Preferably, in step S2, the mass ratio of the product of S1 to the surface oxide is 1:0.8~1.1, based on the assumption that the surface oxide source has completely reacted.

[0017] Preferably, in step S3, based on the complete reaction of the platinum source, the mass ratio of the product of S2 to the Pt particles is 1:0.3~1.4, and more preferably 1:0.6~1.4.

[0018] Preferably, the preparation method specifically includes:

[0019] S1: Add NaOH and zirconium source to the graphene aqueous dispersion, carry out hydrothermal reaction, add H2O2, mix, and separate the product;

[0020] S2: Disperse the S1 product in water, add sodium hydroxide, add silicon source, react at 60~65℃ for 10~15h, and separate the product; or, mix titanium source, oleic acid, oleylamine, reaction solvent and S1 product, react at 150~160℃ for 20~30h, and separate the product.

[0021] S3: Mix the product of S2 with ethylene glycol, add citrate and platinum source, and carry out a reduction reaction at 130~150℃ to separate the product.

[0022] In the preparation of graphene@ZrO2 composite support, the present invention restricts the size of ZrO2 by adding H2O2 after hydrothermal reaction, allowing more ZrO2 to attach to graphene nanosheets, thereby providing more strong anchoring sites for Pt and helping to improve the catalytic efficiency of the catalyst in hydrogen fuel cells.

[0023] Furthermore, this invention utilizes the mild reducing agent ethylene glycol in conjunction with a specific reaction temperature (130~150℃) to reduce platinum ions to zero-valent platinum. At the same time, the addition of the stabilizer citrate can prevent the instantaneous generation of a large number of platinum nuclei. Meanwhile, steric hindrance and electrostatic repulsion prevent Pt particles from "pushing and colliding" (aggregating) with each other, ensuring that each particle can be independently and uniformly distributed on the support surface, thereby improving catalytic performance.

[0024] Preferably, in step S3, the platinum source is chloroplatinic acid, and the mass ratio of chloroplatinic acid to citrate is 1:9~37; the citrate is added in the form of 0.01~0.02 mol / L citrate aqueous solution, and the platinum source is added in the form of 15~25 mg / mL platinum source aqueous solution; the reduction reaction time is 5~7 h.

[0025] Preferably, in step S1, the hydrothermal reaction temperature is 100~120℃ and the time is 5~7h; the volume ratio of H2O2 to water in the graphene aqueous dispersion is 0.005~0.01:1; and the mixing temperature is 50~55℃ and the time is 5~6h.

[0026] Preferably, in step S1, the graphene aqueous dispersion includes graphene nanosheets, hexadecyltrimethylammonium bromide and water, wherein the mass-to-volume ratio of graphene nanosheets to water is 1g:100~150mL, and the mass-to-volume ratio of hexadecyltrimethylammonium bromide to water is 1g:250~300mL.

[0027] The addition of hexadecyltrimethylammonium bromide can reduce the aggregation between graphene nanosheets, which helps to obtain graphene@ZrO2 composite carriers with uniform size and good dispersion of zirconium dioxide particles.

[0028] Thirdly, the present invention provides the application of the hydrogen fuel cell electrode catalyst prepared by the preparation method in a hydrogen fuel cell, wherein the hydrogen fuel cell electrode catalyst is used to catalyze the cathode oxygen reduction reaction or the anode hydrogen oxidation reaction in a hydrogen fuel cell.

[0029] Preferably, the hydrogen fuel cell includes a working electrode, a counter electrode, a reference electrode, and an electrolyte; the working electrode is the hydrogen fuel cell electrode catalyst; the counter electrode is a carbon rod; and the electrolyte contains 0.1~0.5 mol / L HClO4 and 0~0.2 mol / L H3PO4.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) In the catalyst of the present invention, the coordination between graphene and its surface ZrO2 can give the catalyst good conductivity and electrochemical stability, so that the catalyst can achieve high electrocatalytic performance and resistance to chemical substances (such as phosphoric acid) corrosion when used in hydrogen fuel cells.

[0032] (2) In the catalyst of the present invention, the coordination between ZrO2 and SiO2 and / or TiO2 can optimize the environment around the Pt active site, further improve the electrochemical stability of the catalyst, and enable it to maintain high catalytic efficiency in corrosive environments (such as phosphoric acid electrolyte). Attached Figure Description

[0033] Figure 1 The ORR polarization curves of the catalysts in Examples 1-3 and the Pt / C catalyst in O2-saturated 0.1 mol / L HClO4 solution are shown.

[0034] Figure 2 The ORR polarization curves of the catalysts in Comparative Examples 1-3 and the Pt / C catalyst in O2-saturated 0.1 mol / L HClO4 solution are shown.

[0035] Figure 3 The ORR polarization curves of the catalysts of Comparative Examples 1 and 3, as well as the Pt / C catalyst, in O2-saturated 0.1 mol / L HClO4 solution and a mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4 are shown.

[0036] Figure 4 These are the ORR polarization curves of the catalysts of Examples 1, 4, 4, and 5 in O2-saturated 0.1 mol / L HClO4 solution and a mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4.

[0037] Figure 5 The ORR polarization curves of the catalysts of Comparative Examples 6 and 7 in O2-saturated 0.1 mol / L HClO4 solution and 0.1 mol / L HClO4 + 0.1 mol / L H3PO4 mixed solution are shown. Detailed Implementation

[0038] The present invention will now be described through specific embodiments and comparative examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0039] Example 1: Preparation of GNS@(ZrO2-TiO2)-Pt

[0040] This embodiment prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@(ZrO2-TiO2)-Pt") through the following steps:

[0041] S1: Synthesis of GNS@ZrO2 complex:

[0042] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0043] S1.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S1.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0044] S1.3: Transfer the mixed reaction solution obtained in step S1.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0045] S1.4: Transfer the hydrothermal reaction product mixture obtained in step S1.3 to a 100 mL round-bottom flask, add 0.128 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0046] S1.5: The mixture obtained in step S1.4 is centrifuged to remove excess solution, and the wet solid is dried overnight to obtain the GNS@ZrO2 composite, which consists of graphene and a ZrO2 layer coated on its surface.

[0047] S2: TiO2 is bound to the GNS@ZrO2 complex.

[0048] S2.1: Add 50 mL of cyclohexane, 15 mL of oleic acid, 0.5 mL of tetrabutyl titanate (TBT) and 5 mL of oleylamine to a beaker in sequence, and form a homogeneous solution under vigorous magnetic stirring.

[0049] S2.2: 123 mg of GNS@ZrO2 complex and 61.5 mg of cetyltrimethylammonium bromide were dispersed in the homogeneous solution obtained in step S2.1, and the mixture was sonicated at room temperature for 2 hours to form a suspension, thus obtaining a mixed reaction solution.

[0050] S2.3: The mixed reaction solution obtained in step S2.2 is transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 150°C for 24 hours. After cooling, excess solution is removed by centrifugation, and the wet solid is dried overnight to obtain GNS@(ZrO2-TiO2) composite carrier. The composite carrier is composed of graphene, a ZrO2 layer coated on the surface of graphene, and TiO2 bonded to the surface of the ZrO2 layer.

[0051] S3: Platinum nanoparticles loaded on GNS@(ZrO2-TiO2) composite support:

[0052] S3.1: Mix 100 mg of GNS@(ZrO2-TiO2) composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@(ZrO2-TiO2) composite carrier-ethylene glycol dispersion.

[0053] S3.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@(ZrO2-TiO2) composite carrier-ethylene glycol dispersion obtained in step S3.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0054] S3.3: Transfer the mixed reaction solution obtained in step S3.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0055] S3.4: The mixture of reduction reaction products obtained in step S3.3 is centrifuged (10,000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@(ZrO2-TiO2)-Pt). The catalyst is composed of GNS@(ZrO2-TiO2) composite support and Pt particles supported thereon.

[0056] Example 2: Preparation of GNS@(ZrO2-TiO2)-Pt-1

[0057] The only difference between this embodiment and Example 1 is that the amount of chloroplatinic acid aqueous solution used in step S3.2 is reduced; the remaining raw materials and steps are the same as in Example 1. Specifically, this embodiment prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@(ZrO2-TiO2)-Pt-1") through the following steps:

[0058] S1: Synthesis of GNS@ZrO2 complex:

[0059] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0060] S1.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S1.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0061] S1.3: Transfer the mixed reaction solution obtained in step S1.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0062] S1.4: Transfer the hydrothermal reaction product mixture obtained in step S1.3 to a 100 mL round-bottom flask, add 0.128 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0063] S1.5: The mixture obtained in step S1.4 is centrifuged to remove excess solution, and the wet solid is dried overnight to obtain the GNS@ZrO2 composite, which consists of graphene and a ZrO2 layer coated on its surface.

[0064] S2: TiO2 is bound to the GNS@ZrO2 complex.

[0065] S2.1: Add 50 mL of cyclohexane, 15 mL of oleic acid, 0.5 mL of tetrabutyl titanate (TBT) and 5 mL of oleylamine to a beaker in sequence, and form a homogeneous solution under vigorous magnetic stirring.

[0066] S2.2: 123 mg of GNS@ZrO2 complex and 61.5 mg of cetyltrimethylammonium bromide were dispersed in the homogeneous solution obtained in step S2.1, and the mixture was sonicated at room temperature for 2 hours to form a suspension, thus obtaining a mixed reaction solution.

[0067] S2.3: The mixed reaction solution obtained in step S2.2 is transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 150°C for 24 hours. After cooling, excess solution is removed by centrifugation, and the wet solid is dried overnight to obtain GNS@(ZrO2-TiO2) composite carrier. The composite carrier is composed of graphene, a ZrO2 layer coated on the surface of graphene, and TiO2 bonded to the surface of the ZrO2 layer.

[0068] S3: Platinum nanoparticles loaded on GNS@(ZrO2-TiO2) composite support:

[0069] S3.1: Mix 100 mg of GNS@(ZrO2-TiO2) composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@(ZrO2-TiO2) composite carrier-ethylene glycol dispersion.

[0070] S3.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 3.54 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@(ZrO2-TiO2) composite carrier-ethylene glycol dispersion obtained in step S3.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0071] S3.3: Transfer the mixed reaction solution obtained in step S3.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0072] S3.4: The mixture of reduction reaction products obtained in step S3.3 is centrifuged (10000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@(ZrO2-TiO2)-Pt-1), which is composed of GNS@(ZrO2-TiO2) composite support and Pt particles supported thereon.

[0073] Example 3: Preparation of GNS@(ZrO2-TiO2)-Pt-2

[0074] The only difference between this embodiment and Example 1 is that the amount of chloroplatinic acid aqueous solution used in step S3.2 is increased; the remaining raw materials and steps are the same as in Example 1. Specifically, this embodiment prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@(ZrO2-TiO2)-Pt-2") through the following steps:

[0075] S1: Synthesis of GNS@ZrO2 complex:

[0076] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0077] S1.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S1.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0078] S1.3: Transfer the mixed reaction solution obtained in step S1.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0079] S1.4: Transfer the hydrothermal reaction product mixture obtained in step S1.3 to a 100 mL round-bottom flask, add 0.128 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0080] S1.5: The mixture obtained in step S1.4 is centrifuged to remove excess solution, and the wet solid is dried overnight to obtain the GNS@ZrO2 composite, which consists of graphene and a ZrO2 layer coated on its surface.

[0081] S2: TiO2 is bound to the GNS@ZrO2 complex.

[0082] S2.1: Add 50 mL of cyclohexane, 15 mL of oleic acid, 0.5 mL of tetrabutyl titanate (TBT) and 5 mL of oleylamine to a beaker in sequence, and form a homogeneous solution under vigorous magnetic stirring.

[0083] S2.2: 123 mg of GNS@ZrO2 complex and 61.5 mg of cetyltrimethylammonium bromide were dispersed in the homogeneous solution obtained in step S2.1, and the mixture was sonicated at room temperature for 2 hours to form a suspension, thus obtaining a mixed reaction solution.

[0084] S2.3: The mixed reaction solution obtained in step S2.2 is transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 150°C for 24 hours. After cooling, excess solution is removed by centrifugation, and the wet solid is dried overnight to obtain GNS@(ZrO2-TiO2) composite carrier. The composite carrier is composed of graphene, a ZrO2 layer coated on the surface of graphene, and TiO2 bonded to the surface of the ZrO2 layer.

[0085] S3: Platinum nanoparticles loaded on GNS@(ZrO2-TiO2) composite support:

[0086] S3.1: Mix 100 mg of GNS@(ZrO2-TiO2) composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@(ZrO2-TiO2) composite carrier-ethylene glycol dispersion.

[0087] S3.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 14.16 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@(ZrO2-TiO2) composite carrier-ethylene glycol dispersion obtained in step S3.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0088] S3.3: Transfer the mixed reaction solution obtained in step S3.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0089] S3.4: The mixture of reduction reaction products obtained in step S3.3 is centrifuged (10000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@(ZrO2-TiO2)-Pt-1), which is composed of GNS@(ZrO2-TiO2) composite support and Pt particles supported thereon.

[0090] Application Example 1: Hydrogen fuel cell (electrolyte is 0.1 mol / L HClO4 solution)

[0091] The intrinsic oxygen reduction reaction (ORR) activity of the catalysts prepared in Examples 1-3 and a commercial 40 wt% Pt / C catalyst (consisting of a carbon support and Pt supported thereon, with a Pt content of 40 wt%) was evaluated using linear sweep voltammetry on a rotating disk electrode. The tests were conducted in an O2-saturated 0.1 mol / L HClO4 solution using a three-electrode system: the working electrodes were the catalysts prepared in Examples 1-3 and the commercial 40 wt% Pt / C catalyst, respectively; the counter electrode was a carbon rod; and the reference electrode was Ag / AgCl. The electrode rotation speed was kept constant at 1600 rpm, and the O2 flow rate was kept constant at 20 mL / min during the tests. Linear sweep voltammetry was performed in the range of 0.2–1.0 V vs. RHE, and the obtained ORR polarization curves are shown below. Figure 1 As shown ( Figure 1 In the middle, "E" 1 / 2 "Indicates half-wave potential".

[0092] Figure 1 The test results show that the catalyst in Example 1 (GNS@(ZrO2-TiO2)-Pt) can provide a half-wave potential of 0.910 V vs. RHE, the catalyst in Example 2 (GNS@(ZrO2-TiO2)-Pt-1) can provide a half-wave potential of 0.881 V vs. RHE, and the catalyst in Example 3 (GNS@(ZrO2-TiO2)-Pt-2) can provide a half-wave potential of 0.911 V vs. RHE. These results indicate that the amount of platinum source used affects the catalytic performance of the catalyst during Pt loading. Too low a amount will decrease the catalytic performance, while too high a amount will not further improve the performance but will increase the cost of the catalyst. The reason for this is that too low a amount of platinum source results in fewer catalytic active sites, while too high a amount will cause the active sites to aggregate.

[0093] Comparative Example 1: Preparation of GNS@ZrO2-Pt

[0094] The only difference between this comparative example and Example 1 is that, in step S1, TiO2 was not bonded to the surface of GNS@ZrO2; all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@ZrO2-Pt") through the following steps:

[0095] S1: Synthesis of GNS@ZrO2 composite support:

[0096] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0097] S1.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S1.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0098] S1.3: Transfer the mixed reaction solution obtained in step S1.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0099] S1.4: Transfer the hydrothermal reaction product mixture obtained in step S1.3 to a 100 mL round-bottom flask, add 0.255 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0100] S1.5: Remove excess solution from the mixture obtained in step S1.4 by centrifugation, and dry the wet solid overnight to obtain the GNS@ZrO2 composite carrier.

[0101] S2: Platinum nanoparticles loaded on GNS@ZrO2 composite support:

[0102] S2.1: Mix 100 mg of GNS@ZrO2 composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@ZrO2 composite carrier-ethylene glycol dispersion.

[0103] S2.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@ZrO2 composite carrier-ethylene glycol dispersion obtained in step S2.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0104] S2.3: Transfer the mixed reaction solution obtained in step S2.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0105] S2.4: Centrifuge the mixture of reduction reaction products obtained in step S2.3 (10000 rpm, 10 minutes) to collect the powder, wash it three times alternately with distilled water and ethanol, and freeze-dry it for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@ZrO2-Pt).

[0106] Comparative Example 2: Preparation of ZrO2-Pt

[0107] The only difference between this comparative example and Comparative Example 1 is that graphene nanosheets and hexadecyltrimethylammonium bromide were not added in step S1; all other raw materials and steps are the same as in Comparative Example 1. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "ZrO2-Pt") through the following steps:

[0108] S1: Synthesis of ZrO2 support:

[0109] S1.1: Dissolve 0.25 g sodium hydroxide and 0.25 g basic zirconium carbonate ((ZrO)2(OH)2CO3) in 50 mL of water and stir for 30 minutes to obtain a mixed reaction solution.

[0110] S1.2: Transfer the mixed reaction solution obtained in step S1.1 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0111] S1.3: Transfer the hydrothermal reaction product mixture obtained in step S1.2 to a 100 mL round-bottom flask, add 0.255 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0112] S1.4: Remove excess solution from the mixture obtained in step S1.3 by centrifugation, and dry the wet solid overnight to obtain ZrO2 support.

[0113] S2: Platinum nanoparticles loaded on a ZrO2 support:

[0114] S2.1: Mix 100 mg ZrO2 carrier with 125 mL ethylene glycol and stir for 30 minutes to obtain a ZrO2 carrier-ethylene glycol dispersion.

[0115] S2.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the ZrO2 support-ethylene glycol dispersion obtained in step S2.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0116] S2.3: Transfer the mixed reaction solution obtained in step S2.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0117] S2.4: Centrifuge the mixture of reduction reaction products obtained in step S2.3 (10000 rpm, 10 minutes) to collect the powder, wash it three times alternately with distilled water and ethanol, and freeze-dry it for 24 hours to obtain the hydrogen fuel cell electrode catalyst (ZrO2-Pt).

[0118] Comparative Example 3: Preparation of GNS-Pt

[0119] The only difference between this comparative example and Comparative Example 1 is that ZrO2 was not composited on the surface of the graphene nanosheets in step S1; all other raw materials and steps are the same as in Comparative Example 1. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS-Pt") through the following steps:

[0120] S1: 100 mg of graphene nanosheets and 50 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of ethylene glycol and sonicated at room temperature for 2 hours to form a suspension, thus obtaining a graphene-ethylene glycol dispersion.

[0121] S2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the graphene-ethylene glycol dispersion obtained in step S1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0122] S3: Transfer the mixed reaction solution obtained in step S2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixture of reduction reaction products.

[0123] S4: Centrifuge the mixture of reduction reaction products obtained in step S3 (10000 rpm, 10 minutes) to collect the powder, wash it three times alternately with distilled water and ethanol, and freeze-dry it for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS-Pt).

[0124] Application Example 2: Hydrogen fuel cell (electrolyte is 0.1 mol / L HClO4 solution)

[0125] The intrinsic activity of the oxygen reduction reaction (ORR) of the catalysts prepared in Comparative Examples 1-3 and the commercial 40 wt% Pt / C catalyst was evaluated using linear sweep voltammetry on a rotating disk electrode. The tests were conducted in an O2-saturated 0.1 mol / L HClO4 solution using a three-electrode system: the working electrodes were the catalysts prepared in Comparative Examples 1-3 and the commercial 40 wt% Pt / C catalyst, respectively; the counter electrode was a carbon rod; and the reference electrode was Ag / AgCl. The electrode rotation speed was kept constant at 1600 rpm, and the O2 flow rate was kept constant at 20 mL / min during the tests. Linear sweep voltammetry was performed in the range of 0.2–1.0 V vs. RHE, and the obtained ORR polarization curves are shown below. Figure 2 As shown ( Figure 2 In the middle, "E" 1 / 2 "Indicates half-wave potential".

[0126] Figure 2The test results showed that the catalyst in Comparative Example 1 (GNS@ZrO2-Pt) provided a half-wave potential of 0.885 V vs. RHE, the catalyst in Comparative Example 2 (ZrO2-Pt) provided a half-wave potential of 0.740 V vs. RHE, and the catalyst in Comparative Example 3 (GNS-Pt) provided a half-wave potential of 0.801 V vs. RHE. These results indicate that the synergistic effect of ZrO2 and graphene in the support can improve the catalytic performance of the catalyst. The reason for this is that graphene provides good conductivity to the catalyst support, while ZrO2 provides strong anchoring sites for Pt, facilitating the dispersion and firm bonding of Pt on the composite support surface. Therefore, the synergistic effect of the two can achieve higher catalytic efficiency.

[0127] Application Example 3: Hydrogen fuel cell (electrolytes are 0.1 mol / L HClO4 solution and 0.1 mol / L HClO4 + 0.1 mol / L H3PO4 mixed solution respectively)

[0128] The intrinsic activity of the oxygen reduction reaction (ORR) of the catalysts prepared in Comparative Examples 1 and 3, as well as the commercial 40 wt% Pt / C catalyst, was evaluated using linear sweep voltammetry on a rotating disk electrode. Tests were conducted in O2-saturated 0.1 mol / L HClO4 solution and an O2-saturated mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4, respectively, using a three-electrode system: the working electrodes were the catalysts prepared in Examples 1 and 2, and the commercial 40 wt% Pt / C catalyst, respectively; the counter electrode was a carbon rod; and the reference electrode was Ag / AgCl. During the tests, the electrode rotation speed was kept constant at 1600 rpm, and the O2 flow rate was kept constant at 20 mL / min. Linear sweep voltammetry was performed in the range of 0.2–1.0 V vs. RHE, and the obtained ORR polarization curves are shown below. Figure 3 As shown ( Figure 3 In the middle, "E" 1 / 2 "E" represents the half-wave potential measured in a 0.1 mol / L HClO4 solution. 1 / 2 ' " indicates the half-wave potential measured in a mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4.

[0129] Figure 3The test results showed that after the addition of phosphoric acid, the half-wave potential of the catalyst in Comparative Example 1 (GNS@ZrO2-Pt) decreased by 37 mV, the half-wave potential of the catalyst in Comparative Example 3 (GNS-Pt) decreased by 52 mV, and the half-wave potential of the commercial 40 wt% Pt / C catalyst decreased by 63 mV. The decrease in half-wave potential of Comparative Example 1 was significantly smaller than that of Comparative Example 3 and the Pt / C catalyst. These results indicate that by composite ZrO2 on the graphene surface, the electrochemical stability of the catalyst can be improved. The reason for this is that ZrO2 has a robust crystal structure, high electrochemical stability, and can provide strong anchoring sites for Pt. These characteristics enable it to mitigate the corrosion of graphene, and even if some graphene is corroded, ZrO2 can maintain the porous structure of the catalyst to a certain extent, preventing its collapse and thus maintaining the dispersion and accessibility of active sites.

[0130] Example 4: Preparation of GNS@(ZrO2-SiO2)-Pt

[0131] This embodiment prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@(ZrO2-SiO2)-Pt") through the following steps:

[0132] S1: Synthesis of GNS@ZrO2 complex:

[0133] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0134] S1.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S1.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0135] S1.3: Transfer the mixed reaction solution obtained in step S1.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0136] S1.4: Transfer the hydrothermal reaction product mixture obtained in step S1.3 to a 100 mL round-bottom flask, add 0.128 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0137] S1.5: The mixture obtained in step S1.4 is centrifuged to remove excess solution, and the wet solid is dried overnight to obtain the GNS@ZrO2 composite, which consists of graphene and a ZrO2 layer coated on its surface.

[0138] S2: SiO2 is bound to the GNS@ZrO2 composite.

[0139] S2.1: 370 mg of GNS@ZrO2 complex and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and sonicated at room temperature for 2 hours to form a suspension, thus obtaining an aqueous dispersion of GNS@ZrO2 complex.

[0140] S2.2: After preheating the aqueous dispersion of the GNS@ZrO2 complex obtained in step S2.1 to 60℃ and keeping it at that temperature for 10 minutes, add 1.85 mL of 2 mol / L sodium hydroxide solution to obtain an alkaline mixture.

[0141] S2.3: After pre-diluting the orthoethyl silicate with ethanol at a volume ratio of 1:4, take 7.4 mL and add it to the alkaline mixture obtained in step S2.2 by gentle shaking to obtain a mixed reaction solution.

[0142] S2.4: The mixed reaction solution obtained in step S2.3 is aged at 60°C for 12 hours to complete the coating process. Then, the black precipitate is collected by centrifugation, washed with ethanol, and freeze-dried for 24 hours to obtain GNS@(ZrO2-SiO2) composite carrier. The composite carrier is composed of graphene, a ZrO2 layer coated on the surface of graphene, and SiO2 bonded to the surface of the ZrO2 layer.

[0143] S3: Platinum nanoparticles loaded on GNS@(ZrO2-SiO2) composite support:

[0144] S3.1: Mix 100 mg of GNS@(ZrO2-SiO2) composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@(ZrO2-SiO2) composite carrier-ethylene glycol dispersion.

[0145] S3.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@(ZrO2-SiO2) composite carrier-ethylene glycol dispersion obtained in step S3.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0146] S3.3: Transfer the mixed reaction solution obtained in step S3.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0147] S3.4: The mixture of reduction reaction products obtained in step S3.3 is centrifuged (10000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@(ZrO2-SiO2)-Pt). The catalyst is composed of GNS@(ZrO2-SiO2) composite support and Pt particles supported thereon.

[0148] Comparative Example 4: Preparation of GNS@SiO2-Pt

[0149] The only difference between this comparative example and Example 4 is that ZrO2 was not composited on the surface of the graphene nanosheets in step S1; all other raw materials and steps are the same as in Example 4. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@SiO2-Pt") through the following steps:

[0150] S1: Synthesis of GNS@SiO2 composite support:

[0151] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0152] S1.2: After preheating the graphene aqueous dispersion obtained in step S1.1 to 60℃ and keeping it at that temperature for 10 minutes, add 3.7 mL of 2 mol / L sodium hydroxide solution to obtain an alkaline mixture.

[0153] S1.3: After pre-diluting the orthosilicate with ethanol at a volume ratio of 1:4, take 14.8 mL and add it to the alkaline mixture obtained in step S1.2 by gentle shaking to obtain a mixed reaction solution.

[0154] S1.4: The mixed reaction solution obtained in step S1.3 is aged at 60°C for 12 hours to complete the coating process. Then, the black precipitate is collected by centrifugation, washed with ethanol, and freeze-dried for 24 hours to obtain the GNS@SiO2 composite carrier. The composite carrier is composed of graphene and SiO2 bound to its surface.

[0155] S2: Platinum nanoparticles loaded on GNS@SiO2 composite support:

[0156] S2.1: Mix 100 mg of GNS@SiO2 composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@SiO2 composite carrier-ethylene glycol dispersion.

[0157] S2.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@SiO2 composite carrier-ethylene glycol dispersion obtained in step S2.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0158] S2.3: Transfer the mixed reaction solution obtained in step S2.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0159] S2.4: The mixture of reduction reaction products obtained in step S2.3 is centrifuged (10,000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@SiO2-Pt). The catalyst is composed of GNS@SiO2 composite support and Pt particles supported thereon.

[0160] Comparative Example 5: Preparation of GNS@TiO2-Pt

[0161] The only difference between this comparative example and Example 1 is that ZrO2 was not composited on the surface of the graphene nanosheets in step S1; all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@TiO2-Pt") through the following steps:

[0162] S1: Synthesis of GNS@TiO2 composite support:

[0163] S1.1: Add 50 mL of cyclohexane, 15 mL of oleic acid, 0.5 mL of tetrabutyl titanate (TBT) and 5 mL of oleylamine to a beaker in sequence, and form a homogeneous solution under vigorous magnetic stirring.

[0164] S1.2: 123 mg of graphene nanosheets and 61.5 mg of cetyltrimethylammonium bromide are dispersed in the homogeneous solution obtained in step S1.1, and the mixture is sonicated at room temperature for 2 hours to form a suspension, thus obtaining a mixed reaction solution.

[0165] S1.3: The mixed reaction solution obtained in step S1.2 is transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 150°C for 24 hours. After cooling, excess solution is removed by centrifugation, and the wet solid is dried overnight to obtain the GNS@TiO2 composite support, which is composed of graphene and TiO2 bound to its surface.

[0166] S2: Platinum nanoparticles loaded on GNS@TiO2 composite support:

[0167] S2.1: Mix 100 mg of GNS@TiO2 composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@TiO2 composite carrier-ethylene glycol dispersion.

[0168] S2.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@TiO2 composite carrier-ethylene glycol dispersion obtained in step S2.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0169] S2.3: Transfer the mixed reaction solution obtained in step S2.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0170] S2.4: The mixture of reduction reaction products obtained in step S2.3 is centrifuged (10,000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@TiO2-Pt). The catalyst is composed of GNS@TiO2 composite support and Pt particles supported thereon.

[0171] Application Example 4: Hydrogen fuel cell (electrolytes are 0.1 mol / L HClO4 solution and 0.1 mol / L HClO4 + 0.1 mol / L H3PO4 mixed solution respectively)

[0172] The intrinsic activity of the catalysts prepared in Example 1 and Comparative Example 5 for the oxygen reduction reaction was evaluated using linear sweep voltammetry on a rotating disk electrode. Tests were conducted in O2-saturated 0.1 mol / L HClO4 solution and O2-saturated mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4, respectively, using a three-electrode system: the working electrodes were the catalysts prepared in Example 1 and Comparative Example 5, respectively; the counter electrode was a carbon rod; and the reference electrode was Ag / AgCl. During the tests, the electrode rotation speed was kept constant at 1600 rpm, and the O2 flow rate was kept constant at 20 mL / min. Linear sweep voltammetry was performed in the range of 0.2–1.0 V vs. RHE, and the obtained ORR polarization curves are shown below. Figure 4 As shown ( Figure 4 In the middle, "E" 1 / 2 "E" represents the half-wave potential measured in a 0.1 mol / L HClO4 solution. 1 / 2 ' " indicates the half-wave potential measured in a mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4.

[0173] Figure 3 and Figure 4 The test results showed that after the addition of phosphoric acid, the half-wave potential of the catalyst (GNS@(ZrO2-TiO2)-Pt) in Example 1 decreased by 19 mV. Figure 4 The half-wave potential of the catalyst (GNS@ZrO2-Pt) in Comparative Example 1 decreased by 37 mV. Figure 3 The half-wave potential of the catalyst (GNS@TiO2-Pt) in Comparative Example 5 decreased by 41 mV. Figure 4 The decrease in half-wave potential in Example 1 was significantly smaller than that in Comparative Examples 1 and 5. These results indicate that, compared to using ZrO2 or TiO2 alone as a support in graphene composites, the sequential composite of ZrO2 and TiO2 in graphene in this invention improves the electrochemical stability of the catalyst. The reason for this is that the ZrO2-TiO2 interface can form a heterogeneous interface charge rearrangement, making the local electronic environment around the Pt active sites more stable.

[0174] Application Example 5: Hydrogen fuel cell (electrolytes are 0.1 mol / L HClO4 solution and 0.1 mol / L HClO4 + 0.1 mol / L H3PO4 mixed solution respectively)

[0175] The intrinsic activity of the catalysts prepared in Example 4 and Comparative Example 4 for the oxygen reduction reaction (ORR) was evaluated using linear sweep voltammetry on a rotating disk electrode. Tests were conducted in O2-saturated 0.1 mol / L HClO4 solution and O2-saturated mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4, respectively, using a three-electrode system: the working electrodes were the catalysts prepared in Example 4 and Comparative Example 4, respectively; the counter electrode was a carbon rod; and the reference electrode was Ag / AgCl. During the tests, the electrode rotation speed was kept constant at 1600 rpm, and the O2 flow rate was kept constant at 20 mL / min. Linear sweep voltammetry was performed in the range of 0.2–1.0 V vs. RHE, and the obtained ORR polarization curves are shown below. Figure 4 As shown ( Figure 4 In the middle, "E" 1 / 2 "E" represents the half-wave potential measured in a 0.1 mol / L HClO4 solution. 1 / 2 ' " indicates the half-wave potential measured in a mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4.

[0176] Figure 3 and Figure 4 The test results showed that after the addition of phosphoric acid, the half-wave potential of the catalyst (GNS@(ZrO2-SiO2)-Pt) in Example 4 decreased by 33 mV. Figure 4The half-wave potential of the catalyst (GNS@ZrO2-Pt) in Comparative Example 1 decreased by 37 mV. Figure 3 The half-wave potential of the catalyst (GNS@SiO2-Pt) in Comparative Example 4 decreased by 63 mV. Figure 4 The half-wave potential decrease in Example 4 was significantly smaller than that in Comparative Examples 1 and 4. These results indicate that, compared to using ZrO2 or SiO2 alone in combination with graphene as a support, the sequential combination of ZrO2 and SiO2 in graphene in this invention improves the electrochemical stability of the catalyst. The reason for this is that the -SiOH groups on the SiO2 surface and the Lewis acid sites on the ZrO2 surface can form a complex acid-base environment, which can alter the solvation and adsorption morphology of anions near the interface, reducing their tendency to form a dense blocking layer near the Pt active sites.

[0177] Comparative Example 6: Preparation of GNS@(TiO2-ZrO2)-Pt

[0178] The only difference between this comparative example and Example 1 is that the order of steps S1 and S2 is reversed; all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@(TiO2-ZrO2)-Pt") through the following steps:

[0179] S1: Synthesis of GNS@TiO2 composite support:

[0180] S1.1: Add 50 mL of cyclohexane, 15 mL of oleic acid, 0.5 mL of tetrabutyl titanate (TBT) and 5 mL of oleylamine to a beaker in sequence, and form a homogeneous solution under vigorous magnetic stirring.

[0181] S1.2: 123 mg of graphene nanosheets and 61.5 mg of cetyltrimethylammonium bromide are dispersed in the homogeneous solution obtained in step S1.1, and the mixture is sonicated at room temperature for 2 hours to form a suspension, thus obtaining a mixed reaction solution.

[0182] S1.3: The mixed reaction solution obtained in step S1.2 is transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and reacted at 150°C for 24 hours. After cooling, excess solution is removed by centrifugation, and the wet solid is dried overnight to obtain the GNS@TiO2 composite support, which is composed of graphene and TiO2 bound to its surface.

[0183] S2: ZrO2 is bound to the GNS@TiO2 complex.

[0184] S2.1: 370 mg GNS@TiO2 complex and 185 mg hexadecyltrimethylammonium bromide were dispersed in 50 mL of water and sonicated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0185] S2.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S2.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0186] S2.3: Transfer the mixed reaction solution obtained in step S2.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0187] S2.4: Transfer the hydrothermal reaction product mixture obtained in step S2.3 to a 100 mL round-bottom flask, add 0.128 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0188] S2.5: The mixture obtained in step S2.4 is centrifuged to remove excess solution, and the wet solid is dried overnight to obtain GNS@(TiO2-ZrO2) composite support. The composite support is composed of graphene, a TiO2 layer coated on the surface of graphene, and ZrO2 bonded to the surface of the TiO2 layer.

[0189] S3: Platinum nanoparticles loaded on GNS@(TiO2-ZrO2) composite support:

[0190] S3.1: Mix 100 mg of GNS@(TiO2-ZrO2) composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@TiO2 composite carrier-ethylene glycol dispersion.

[0191] S3.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@(TiO2-ZrO2) composite carrier-ethylene glycol dispersion obtained in step S2.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0192] S3.3: Transfer the mixed reaction solution obtained in step S2.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0193] S3.4: The mixture of reduction reaction products obtained in step S2.3 is centrifuged (10000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@(TiO2-ZrO2)-Pt). The catalyst is composed of GNS@(TiO2-ZrO2) composite support and Pt particles supported thereon.

[0194] Comparative Example 7: Preparation of GNS@(SiO2-ZrO2)-Pt

[0195] The only difference between this comparative example and Example 4 is that the order of steps S1 and S2 is reversed; all other raw materials and steps are the same as in Example 4. Specifically, this comparative example prepares a hydrogen fuel cell electrode catalyst (denoted as "GNS@SiO2-ZrO2)-Pt") through the following steps:

[0196] S1: Synthesis of GNS@SiO2 composite support:

[0197] S1.1: 370 mg of graphene nanosheets and 185 mg of cetyltrimethylammonium bromide were dispersed in 50 mL of water and ultrasonically treated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0198] S1.2: After preheating the graphene aqueous dispersion obtained in step S1.1 to 60℃ and keeping it at that temperature for 10 minutes, add 3.7 mL of 2 mol / L sodium hydroxide solution to obtain an alkaline mixture.

[0199] S1.3: After pre-diluting the orthosilicate with ethanol at a volume ratio of 1:4, take 14.8 mL and add it to the alkaline mixture obtained in step S1.2 by gentle shaking to obtain a mixed reaction solution.

[0200] S1.4: The mixed reaction solution obtained in step S1.3 is aged at 60°C for 12 hours to complete the coating process. Then, the black precipitate is collected by centrifugation, washed with ethanol, and freeze-dried for 24 hours to obtain the GNS@SiO2 composite carrier. The composite carrier is composed of graphene and SiO2 bound to its surface.

[0201] S2: ZrO2 is bound to the GNS@SiO2 composite.

[0202] S2.1: 370 mg GNS@SiO2 complex and 185 mg hexadecyltrimethylammonium bromide were dispersed in 50 mL of water and sonicated at room temperature for 2 hours to form a suspension, thus obtaining a graphene aqueous dispersion.

[0203] S2.2: Dissolve 0.25 g of sodium hydroxide and 0.25 g of basic zirconium carbonate ((ZrO)2(OH)2CO3) in the graphene aqueous dispersion obtained in step S2.1, and stir for 30 minutes to obtain a mixed reaction solution.

[0204] S2.3: Transfer the mixed reaction solution obtained in step S2.2 into a 100 mL hydrothermal reactor, heat it at 110°C for 6 hours in the hydrothermal reactor, and after cooling, obtain a hydrothermal reaction product mixture.

[0205] S2.4: Transfer the hydrothermal reaction product mixture obtained in step S2.3 to a 100 mL round-bottom flask, add 0.128 mL of H2O2 to the round-bottom flask while stirring continuously at 50°C, and continue stirring at 50°C for 5 hours to obtain the mixture.

[0206] S2.5: Remove excess solution from the mixture obtained in step S2.4 by centrifugation, and dry the wet solid overnight to obtain GNS@(SiO2-ZrO2) composite carrier. The composite carrier is composed of graphene, a SiO2 layer coated on the surface of graphene, and ZrO2 bonded to the surface of the SiO2 layer.

[0207] S3: Platinum nanoparticles loaded on GNS@(SiO2-ZrO2) composite support:

[0208] S3.1: Mix 100 mg of GNS@(SiO2-ZrO2) composite carrier with 125 mL of ethylene glycol and stir for 30 minutes to obtain GNS@TiO2 composite carrier-ethylene glycol dispersion.

[0209] S3.2: At room temperature, add 1 mL of 0.01 mol / L sodium citrate aqueous solution and 7.08 mL of 20 mg / mL chloroplatinic acid aqueous solution to the GNS@(SiO2-ZrO2) composite carrier-ethylene glycol dispersion obtained in step S2.1, and continue stirring for 1 hour to obtain a mixed reaction solution.

[0210] S3.3: Transfer the mixed reaction solution obtained in step S2.2 to a three-necked flask and reflux at 140°C for 6 hours to completely reduce the platinum, thereby obtaining a mixed solution of reduction reaction products.

[0211] S3.4: The mixture of reduction reaction products obtained in step S2.3 is centrifuged (10000 rpm, 10 minutes) to collect the powder, washed three times alternately with distilled water and ethanol, and freeze-dried for 24 hours to obtain the hydrogen fuel cell electrode catalyst (GNS@(SiO2-ZrO2)-Pt). The catalyst is composed of GNS@(SiO2-ZrO2) composite support and Pt particles supported thereon.

[0212] Application Example 6: Hydrogen fuel cell (electrolytes are 0.1 mol / L HClO4 solution and 0.1 mol / L HClO4 + 0.1 mol / L H3PO4 mixed solution respectively)

[0213] The intrinsic activity of the catalysts prepared in Comparative Examples 6 and 7 for the oxygen reduction reaction (ORR) was evaluated using linear sweep voltammetry on a rotating disk electrode. Tests were conducted in O2-saturated 0.1 mol / L HClO4 solution and O2-saturated mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4, respectively, using a three-electrode system: the working electrodes were the catalysts prepared in Comparative Examples 6 and 7, respectively; the counter electrode was a carbon rod; and the reference electrode was Ag / AgCl. During the tests, the electrode rotation speed was kept constant at 1600 rpm, and the O2 flow rate was kept constant at 20 mL / min. Linear sweep voltammetry was performed in the range of 0.2–1.0 V vs. RHE, and the obtained ORR polarization curves are shown below. Figure 5 As shown ( Figure 5 In the middle, "E" 1 / 2 "E" represents the half-wave potential measured in a 0.1 mol / L HClO4 solution. 1 / 2 ' " indicates the half-wave potential measured in a mixed solution of 0.1 mol / L HClO4 + 0.1 mol / L H3PO4.

[0214] Figure 4 and Figure 5 The test results showed that after the addition of phosphoric acid, the half-wave potential of the catalyst (GNS@(ZrO2-TiO2)-Pt) in Example 1 decreased by 19 mV. Figure 4 The half-wave potential of the catalyst in Comparative Example 6 (GNS@(TiO2-ZrO2)-Pt) decreased by 34 mV. Figure 5 The half-wave potential decrease in Example 1 was significantly smaller than that in Comparative Example 6; the half-wave potential of the catalyst (GNS@(ZrO2-SiO2)-Pt) in Example 4 decreased by 33 mV. Figure 4 The half-wave potential of the catalyst in Comparative Example 7 (GNS@(SiO2-ZrO2)-Pt) decreased by 43 mV. Figure 5The half-wave potential decrease in Example 4 was significantly smaller than that in Comparative Example 6. These results indicate that the order in which ZrO2, SiO2, and / or TiO2 are bonded to graphene during the preparation of the composite support affects the electrochemical stability of the final catalyst. This invention employs a sequence of first bonding ZrO2 and then SiO2 and / or TiO2, which imparts higher electrochemical stability to the catalyst. The reason for this is that when ZrO2 is in the inner layer, its strong anchoring and high structural stability primarily stabilize Pt and the framework, while TiO2 and / or SiO2 on the catalyst surface effectively regulate the adsorption of anions (such as phosphate ions), making it easier to achieve the optimal microenvironment for the cathodic oxygen reduction reaction (ORR) near Pt.

Claims

1. A method for preparing a hydrogen fuel cell electrode catalyst, characterized by, include: S1: A ZrO2 layer is generated on the surface of graphene through in-situ reaction with a zirconium source; the mass ratio of graphene to ZrO2 is 1:0.4~0.6, based on the complete reaction of the zirconium source. S2: A surface oxide is generated on the surface of the S1 product through an in-situ reaction with a surface oxide source; the surface oxide source is a silicon source and / or a titanium source; based on the complete reaction of the surface oxide source, the mass ratio of the S1 product to the surface oxide is 1:0.8~1.

1. S3: Pt particles are generated on the surface of the product of S2 through in-situ reaction with a platinum source to obtain a hydrogen fuel cell electrode catalyst; the hydrogen fuel cell electrode catalyst includes a composite support and Pt particles supported on the composite support; the composite support includes: graphene, a ZrO2 layer coated on the graphene, and a surface oxide bonded to the surface of the ZrO2 layer; the surface oxide is SiO2 and / or TiO2.

2. The production method according to claim 1, characterized by, The surface oxides are SiO2 and TiO2.

3. The production method according to claim 1, characterized by, In step S3, based on the assumption that the platinum source reacts completely, the mass ratio of the product from S2 to the Pt particles is 1:0.3~1.

4.

4. The preparation method according to claim 1, characterized in that, Specifically, it includes: S1: Add NaOH and zirconium source to the graphene aqueous dispersion, carry out hydrothermal reaction, add H2O2, mix, and separate the product; S2: Disperse the product of S1 in water, add sodium hydroxide, add silicon source, react at 60~65℃ for 10~15h, and separate the product; Alternatively, the titanium source, oleic acid, oleylamine, reaction solvent and S1 product are mixed and reacted at 150~160℃ for 20~30h, and the product is separated. S3: Mix the product of S2 with ethylene glycol, add citrate and platinum source, and carry out a reduction reaction at 130~150℃ to separate the product.

5. The preparation method according to claim 4, characterized in that, In step S3, the platinum source is chloroplatinic acid, and the mass ratio of chloroplatinic acid to citrate is 1:9~37; the citrate is added in the form of 0.01~0.02 mol / L citrate aqueous solution, and the platinum source is added in the form of 15~25 mg / mL platinum source aqueous solution; the reduction reaction takes 5~7 hours.

6. The preparation method according to claim 4, characterized in that, In step S1, the hydrothermal reaction temperature is 100~120℃ and the time is 5~7h; the volume ratio of H2O2 to water in the graphene aqueous dispersion is 0.005~0.01:1; the mixing temperature is 50~55℃ and the time is 5~6h.

7. The preparation method according to claim 4, characterized in that, In step S1, the graphene aqueous dispersion includes graphene nanosheets, hexadecyltrimethylammonium bromide and water, wherein the mass-volume ratio of graphene nanosheets to water is 1g:100~150mL, and the mass-volume ratio of hexadecyltrimethylammonium bromide to water is 1g:250~300mL.

8. A hydrogen fuel cell electrode catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the hydrogen fuel cell electrode catalyst according to claim 8 in a hydrogen fuel cell, characterized in that, The hydrogen fuel cell electrode catalyst is used to catalyze the cathode oxygen reduction reaction or the anode hydrogen oxidation reaction in the hydrogen fuel cell.

10. Use according to claim 9, characterized in that, The hydrogen fuel cell includes a working electrode, a counter electrode, a reference electrode, and an electrolyte; the working electrode is the electrode catalyst of the hydrogen fuel cell; the counter electrode is a carbon rod; the electrolyte contains 0.1~0.5 mol / L HClO4 and 0~0.2 mol / L H3PO4.

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