Graphene oxide-wrapped pt-sn s hydrogen fuel cell catalyst and method of making

Abstract

The application discloses a hydrogen fuel cell catalyst of graphene oxide wrapped Pt-SnS, and the catalyst is spherical, the catalyst takes sulfonated graphene oxide as a carrier, the sulfonated graphene oxide is in a spherical reticular structure, Pt-SnS is grafted on the sulfonated graphene oxide carrier, and the Pt-SnS is coated in the inside of the spherical reticular carrier. The application also discloses a preparation method of the hydrogen fuel cell catalyst of graphene oxide wrapped Pt-SnS. In the catalyst, the sulfonated graphene oxide forms a spherical wrapping of a reaction active site, so that the catalytic stability of Pt nanoparticles is improved; after high-temperature reduction, a Pt-SnS alloy is formed in situ on the Pt, the SnS can change the d-band center potential in the Pt, so that the Pt surface electron distribution is changed, the active site is favorable to the adsorption of oxygen-containing functional groups, and then the catalytic efficiency of the catalyst is improved.

Description

Technical Field

[0001] This invention relates to a hydrogen fuel cell catalyst with Pt-SnS encapsulated in graphene oxide, and also to a method for preparing the above catalyst. Background Technology

[0002] In proton exchange membrane hydrogen fuel cell batteries, the catalyst is a crucial component, accounting for approximately 40% of the stack cost. The catalytic stability and efficiency of the hydrogen fuel cell catalyst significantly impact the cost and lifespan of the fuel cell. Catalytic stability affects the stack's lifespan, while catalytic efficiency influences the efficiency of hydrogen-to-electricity conversion. Currently, Pt nanocatalysts in hydrogen fuel cell batteries are prone to agglomeration during use and, with the corrosion of the carbon support material, detach from the proton exchange membrane, causing collapse and loss of catalytic activity. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a hydrogen fuel cell catalyst with graphene oxide-encapsulated Pt-SnS, which can effectively solve the problems of easy agglomeration and collapse caused by the detachment of carbon support from the proton exchange membrane in existing Pt nanocatalysts. Another purpose of this invention is to provide a method for preparing the above-mentioned catalyst.

[0004] Technical solution: The hydrogen fuel cell catalyst of graphene oxide encapsulating Pt-SnS described in this invention is spherical. The catalyst uses sulfonated graphene oxide as a support. The sulfonated graphene oxide has a spherical network structure. Pt-SnS is grafted onto the sulfonated graphene oxide support, and the Pt-SnS is encapsulated inside the spherical network support.

[0005] The preparation method of the above-mentioned graphene oxide-encapsulated Pt-SnS hydrogen fuel cell catalyst includes the following steps:

[0006] (1) Preparation of GO-SO3H: Graphene oxide (GO) was added to a saturated ammonium sulfate solution, ultrasonically mixed, and then sulfonated at high temperature. The product was washed and filtered to obtain sulfonated GO-SO3H. The purpose of sulfonation is to give graphene oxide sulfonated functional groups, which facilitates the grafting of active sites.

[0007] (2) Preparation of PS / SnO2: Stannous chloride is added to concentrated hydrochloric acid, and then an aqueous solution of amino-modified polystyrene spheres (PS) is added to it. After ultrasonic mixing at 50°C, PS / SnO2 is obtained.

[0008] (3) Preparation of Pt / GO-SO3H: Chloroplatinic acid is added to water to obtain chloroplatinic acid aqueous solution. GO / SO3H from step (1) is added to chloroplatinic acid aqueous solution. The mixture is added to ethylene glycol (as an oxidant). After sonication, the product obtained from the reaction is filtered and washed to obtain Pt / GO-SO3H. Pt / GO-SO3H uses GO-SO3H as a support and Pt nanoparticles are loaded on the GO-SO3H support.

[0009] (4) Preparation of spherical Pt-SnO2 / GO-SO3H: PS / SnO2 from step (2) is mixed with Pt / GO-SO3H from step (3). GO-SO3H self-assembles and encapsulates PS / SnO2. After heating, spherical Pt-SnO2 / GO-SO3H is obtained. Pt-SnO2 / GO-SO3H uses GO-SO3H as a support. The support GO-SO3H has a spherical network structure. Pt-SnO2 is encapsulated and loaded in the spherical network structure of the GO-SO3H support.

[0010] (5) The spherical Pt-SnO2 / GO-SO3H from step (4) is mixed with thioacetamide, and then added to water for ultrasonic mixing and heated in a nitrogen protective gas to obtain a spherical Pt-SnS / GO-SO3H catalyst.

[0011] In step (1), the mass-to-volume ratio of graphene oxide to saturated ammonium sulfate solution is 0.5 g: 10 mL; the ultrasonic time is 20 minutes.

[0012] In step (1), the sulfonation temperature is 235℃ and the sulfonation time is 1h.

[0013] In step (2), the mass-to-volume ratio of stannous chloride to concentrated hydrochloric acid is 5–20 g: 30 mL; and the mass concentration of concentrated hydrochloric acid is 37%.

[0014] In step (2), the mass-volume ratio of stannous chloride and the aqueous solution of aminated polystyrene spheres is 5 g: 1.5 mL; and the mass concentration of the aminated polystyrene spheres in the aqueous solution is 20%, and the particle size of the aminated polystyrene spheres is 100 nm.

[0015] In step (3), the mass-to-volume ratio of chloroplatinic acid to ethylene glycol is 0.2 g: 20 mL.

[0016] In step (4), the heating temperature is 120℃ and the heating time is 3 hours. The purpose of heating is to remove the aminated polystyrene spheres.

[0017] In step (5), the mass ratio of spherical Pt-SnO2 / GO-SO3H to thioacetamide is 5:1.

[0018] In step (5), the heating temperature is 500℃ and the heating time is 4 hours.

[0019] This invention utilizes SnCl2 to prepare positively charged spherical particles (PS / SnO2) on the surface of aminated polystyrene spheres. This allows negatively charged sulfonated graphene oxide anchored with Pt nanoparticles to self-assemble around the PS / SnO2 spheres via electrostatic interactions. The sulfonated graphene oxide then encapsulates the PS / SnO2. After removing the PS, the sulfonated graphene oxide forms spherical structures that encapsulate the reactive sites (Pt nanoparticles), preventing the catalyst from detaching from the support and thus improving the catalytic stability of the Pt nanoparticles. High-temperature reduction forms a Pt-SnS alloy in situ on the Pt. SnS alters the d-band center potential in Pt, changing the electron distribution on the Pt surface and facilitating the adsorption of oxygen-containing functional groups at the active sites, thereby improving the catalyst's catalytic efficiency. This method reduces the amount of platinum used in the oxygen reduction reaction through alloying, lowering costs, and improves the catalytic efficiency by adjusting the d-band center potential in Pt.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The catalyst of the present invention is wrapped with SO3H functional groups and anchored to the reactive active sites by graphene oxide support. On the one hand, it can reduce the problem of agglomeration of reactive active sites, and on the other hand, it can make the catalyst (reactive active sites) less likely to fall off from the support. At the same time, after spherical assembly, it can increase the bonding force between the catalyst support and the membrane electrode surface, and reduce the collapse problem caused by the detachment due to support corrosion. (2) The catalyst of the present invention can also improve the stability of the catalyst reaction by wrapping the reactive active sites with the support. At the same time, the increased specific surface area of ​​the spherical structure enhances its catalytic efficiency (more active sites are loaded). (3) The catalyst of the present invention introduces SnS in situ on the Pt active sites, adjusts the center potential of the d band in Pt, reduces the activation energy of the oxygen reduction reaction of the substance, and thus improves the catalytic performance of the catalyst. Attached Figure Description

[0021] Figure 1 The XRD pattern of the catalyst obtained in Example 3;

[0022] Figure 2 This is a SEM image of the catalyst obtained in Example 3. Detailed Implementation

[0023] Example 1

[0024] The present invention discloses a method for preparing a Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide, comprising the following steps:

[0025] (1) Preparation of GO-SO3H: 0.5g of graphene oxide (GO) was added to 10mL of saturated ammonium sulfate solution, and after ultrasonic mixing for 20 minutes, it was sulfonated at 235℃ for 1h. The product was washed and filtered to obtain sulfonated GO-SO3H. The purpose of sulfonation is to give graphene oxide sulfonated functional groups, which facilitates the grafting of Pt active sites.

[0026] (2) Preparation of PS / SnO2: 10g of stannous chloride was added to 30mL of 37% concentrated hydrochloric acid, and then 3mL of 20wt.% aqueous solution of amino-modified polystyrene spheres (PS) was added. After ultrasonic mixing for 20 minutes, PS / SnO2 was obtained. In PS / SnO2, SnO2 and PS are bonded by covalent bonds. Since Sn is easily oxidized, the surface of the obtained PS / SnO2 is positively charged. The bonding principle of SnO2 and PS is shown in the figure below:

[0027]

[0028] (3) Preparation of Pt / GO-SO3H: Add 0.2g of chloroplatinic acid to 10mL of water to obtain chloroplatinic acid aqueous solution. Add 0.5g of GO / SO3H from step (1) to the chloroplatinic acid aqueous solution. After stirring, add the mixture to 20mL of ethylene glycol. After sonication for 20 minutes, filter and wash the product obtained from the reaction to obtain Pt / GO-SO3H.

[0029] (4) Preparation of spherical Pt-SnO2 / GO-SO3H: 5g of PS / SnO2 from step (2) and 10g of Pt / GO-SO3H from step (3) were mixed. GO-SO3H self-assembled and encapsulated PS / SnO2. The mixture was kept at 120℃ for 3 hours to obtain graphene spherical encapsulated Pt-SnO2 / GO-SO3H.

[0030] (5) The spherical Pt-SnO2 / GO-SO3H from step (4) was mixed with thioacetamide at a mass ratio of 5:1. After mixing, it was added to 10 mL of water and ultrasonically mixed. After mixing, it was kept at 500 °C for 4 hours under nitrogen protection to obtain graphene spherical Pt-SnS / GO-SO3H catalyst.

[0031] Example 2

[0032] The preparation method of Example 2 is exactly the same as that of Example 1, except that stannous chloride was not added in step (2), resulting in Pt / GO-SO3H based on graphene support.

[0033] Example 3

[0034] The preparation method of Example 3 is exactly the same as that of Example 1, except that 5g of stannous chloride is added in step (2) to obtain a graphene spherically encapsulated Pt-SnS / GO-SO3H catalyst.

[0035] Example 4

[0036] The preparation method of Example 4 is exactly the same as that of Example 1, except that 15g of stannous chloride is added in step (2) to obtain a graphene spherically encapsulated Pt-SnS / GO-SO3H catalyst.

[0037] Example 5

[0038] The preparation method of Example 5 is exactly the same as that of Example 1, except that 20g of stannous chloride is added in step (2) to obtain a graphene spherically encapsulated Pt-SnS / GO-SO3H catalyst.

[0039] The particle size, catalytic efficiency, and catalytic stability of the products obtained in Examples 1-5 are shown in Table 1.

[0040] Table 1

[0041]

[0042] As shown in Table 1, the Pt-SnS / GO-SO3H catalyst with graphene oxide spherical encapsulation prepared by adding 10g SnCl2 has the highest catalytic efficiency and the best catalytic stability.

[0043] pass Figure 1 The XRD pattern shows that the three strong diffraction peaks contain SnS and Pt phases, corresponding to JPCDS 39-0354 and JCPDS 04-0802, respectively. Figure 2 The SEM images show that the prepared catalyst is a spherical encapsulated catalyst.

Claims

1. A method for preparing a Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide, characterized in that, Includes the following steps: (1) Preparation of GO-SO3H: Graphene oxide was added to a saturated ammonium sulfate solution, ultrasonically mixed, and then sulfonated at high temperature. The product was washed and filtered to obtain sulfonated GO-SO3H. (2) Preparation of PS / SnO2: Stannous chloride was added to concentrated hydrochloric acid, and then an aqueous solution of amino-modified polystyrene spheres was added to it. After ultrasonic mixing, PS / SnO2 was obtained. (3) Preparation of Pt / GO-SO3H: Chloroplatinic acid is added to water to obtain chloroplatinic acid aqueous solution. GO / SO3H from step (1) is added to chloroplatinic acid aqueous solution. The mixture is added to ethylene glycol. After sonication, the product obtained from the reaction is filtered and washed to obtain Pt / GO-SO3H. Pt / GO-SO3H uses GO-SO3H as a support and Pt nanoparticles are loaded on the GO-SO3H support. (4) Preparation of spherical Pt-SnO2 / GO-SO3H: PS / SnO2 from step (2) is mixed with Pt / GO-SO3H from step (3). GO-SO3H self-assembles and encapsulates PS / SnO2. After heating, spherical Pt-SnO2 / GO-SO3H is obtained. Pt-SnO2 / GO-SO3H uses GO-SO3H as a support. The support GO-SO3H has a spherical network structure. Pt-SnO2 is encapsulated and loaded in the spherical network structure of the GO-SO3H support. (5) The spherical Pt-SnO2 / GO-SO3H from step (4) is mixed with thioacetamide, and then added to water for ultrasonic mixing and heated in a nitrogen protective gas to obtain a spherical Pt-SnS / GO-SO3H catalyst.

2. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (1), the mass-to-volume ratio of graphene oxide to saturated ammonium sulfate solution is 0.5 g: 10 mL.

3. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (1), the sulfonation temperature is 235℃ and the sulfonation time is 1h.

4. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (2), the mass-to-volume ratio of stannous chloride to concentrated hydrochloric acid is 5–20 g: 30 mL; wherein the mass concentration of concentrated hydrochloric acid is 37%.

5. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (2), the mass-volume ratio of stannous chloride and the aqueous solution of aminated polystyrene spheres is 5 g: 1.5 mL; wherein, the mass concentration of the aminated polystyrene spheres in the aqueous solution is 20%.

6. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (3), the mass-to-volume ratio of chloroplatinic acid to ethylene glycol is 0.2 g: 20 mL.

7. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (4), the heating temperature is 120℃ and the heating time is 3 hours.

8. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (5), the mass ratio of spherical Pt-SnO2 / GO-SO3H to thioacetamide is 5:

1.

9. The method for preparing the Pt-SnS hydrogen fuel cell catalyst encapsulated in graphene oxide according to claim 1, characterized in that: In step (5), the heating temperature is 500℃ and the heating time is 4 hours.

10. The graphene oxide-encapsulated Pt-SnS hydrogen fuel cell catalyst prepared by any one of the preparation methods described in claims 1 to 9, characterized in that: The catalyst uses sulfonated graphene oxide as a support. The sulfonated graphene oxide has a spherical network structure, and Pt-SnS is grafted onto the sulfonated graphene oxide support. The Pt-SnS is encapsulated inside the spherical network support.

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