A metal alloy catalyst for proton exchange membrane fuel cells for ships, and its preparation method and application

Abstract

The present invention discloses a metal alloy catalyst for proton exchange membrane fuel cells for ships, as well as its preparation method and application. The metal alloy catalyst for proton exchange membrane fuel cells for ships comprises metal ions selected from platinum, nickel, and cobalt, and a carrier. The metal alloy has a Pt surface and a PtNiCo core-shell structure within it, and the carrier is reduced graphene oxide grafted with sulfonic acid groups. The PtNiCo ternary alloy structure provides a complex shape, thereby increasing the specific surface area. The sulfonic acid groups enhance the stability of the catalyst as an anchoring center for the PtNiCo ternary alloy. The Pt@PtNiCo / RGO-SO3H catalyst exhibits excellent electrochemical performance for oxygen reduction reactions under a simulated proton exchange membrane fuel cell environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical catalysis, and in particular relates to a metal alloy catalyst for a proton exchange membrane fuel cell for ships, and a preparation method and application thereof. Background Art

[0002] Proton exchange membrane fuel cells (PEMFCs) convert chemical energy into electricity through an oxygen reduction reaction at the cathode and a hydrogen oxidation reaction at the anode, without requiring high temperatures. They are ideally suited for converting chemical energy into electricity in marine, automotive, and stationary applications. They offer high efficiency, low temperature, high energy density, and low or zero emissions. Several key components require development, including electrodes, bipolar plates, membranes, and catalysts. However, degradation of commercial Pt / C catalysts is a major concern during fuel cell operation and repeated cycling. Furthermore, the high cost and scarcity of platinum metal must be reduced for future large-scale application. Consequently, graphene-based materials have been sought to improve conductivity and durability, including doping elements and grafting groups onto the 2D graphene surface. Furthermore, the selection of Pt-based alloys can reduce the amount of Pt required, increase the catalyst's specific surface area, and thus improve catalytic efficiency. Binary, ternary, and even quaternary Pt-based metal catalysts have been developed for PEMFCs.

[0003] To commercialize platinum-based metal catalysts, it is necessary to reduce the amount of platinum used, modify the electronic structure, and improve long-term stability. Various methods exist to achieve structural effects, including surface activation, core-shell structures, nanostructures of varying shapes, platinum-skin structures, heat treatment of platinum-based alloys, and surface structural modification of platinum-based alloys. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] In view of the above-mentioned and / or existing deficiencies in the prior art, one of the objects of the present invention is to provide a metal alloy catalyst for proton exchange membrane fuel cells for ships, a preparation method thereof, and an application thereof. The structure of the PtNiCo ternary alloy provides a complex shape, thereby increasing the specific surface area. The sulfonic acid group can improve the stability of the catalyst as an anchoring center of the PtNiCo ternary alloy. Pt@PtNiCo / RGO-SO3H exhibits good electrochemical performance for oxygen reduction reaction under the simulated environment of a proton exchange membrane fuel cell.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: A metal alloy catalyst for a proton exchange membrane fuel cell for a ship, comprising metal ions and a carrier;

[0007] The metal ions are platinum, nickel and cobalt; wherein the surface of the metal alloy is Pt and the interior is a core-shell structure of PtNiCo;

[0008] The carrier is reduced graphene oxide grafted with sulfonic acid groups.

[0009] As a preferred solution of the metal alloy catalyst for proton exchange membrane fuel cells for ships of the present invention, the metal ion loading amount is 10 to 25 wt.%.

[0010] As a preferred embodiment of the metal alloy catalyst for proton exchange membrane fuel cells for ships of the present invention, the atomic ratio of platinum, nickel and cobalt is 1:1:1.

[0011] Another object of the present invention is to provide a method for preparing a metal alloy catalyst for a proton exchange membrane fuel cell for use in ships, comprising: mixing a platinum salt, a cobalt salt, and a nickel salt, ultrasonically mixing the mixture with a reduced graphene oxide carrier grafted with sulfonic acid groups, adding the mixture to an organic solvent, and heating the mixture for reduction reaction to obtain a suspension;

[0012] The suspension is acid-washed, then washed, filtered and dried to obtain a metal alloy catalyst.

[0013] As a preferred embodiment of the method for preparing the metal alloy catalyst for proton exchange membrane fuel cells for ships of the present invention, the platinum salt, cobalt salt and nickel salt are mixed at a ratio of 1:1:1 in terms of the number of metal ion atoms.

[0014] As a preferred embodiment of the preparation method of the metal alloy catalyst for proton exchange membrane fuel cells for ships of the present invention, the catalyst is ultrasonically mixed with the reduced graphene oxide carrier grafted with sulfonic acid groups at a metal ion loading ratio of 10 to 25 wt.%.

[0015] As a preferred embodiment of the method for preparing the metal alloy catalyst for proton exchange membrane fuel cells for ships of the present invention, the heating reduction reaction is carried out at 150° C. in an Ar atmosphere for 2 hours.

[0016] As a preferred embodiment of the method for preparing the metal alloy catalyst for proton exchange membrane fuel cells for ships of the present invention, the method for preparing the reduced graphene oxide grafted with sulfonic acid groups is as follows:

[0017] (NH4)2SO4 and graphene oxide were mixed, ultrasonically dispersed, and evaporated under reduced pressure in a rotary evaporator to obtain a powder;

[0018] The powder is decomposed at 250° C. under a protective atmosphere to obtain reduced graphene oxide grafted with sulfonic acid groups.

[0019] Another object of the present invention is to provide use of the metal alloy catalyst described above in proton exchange membrane fuel cells for ships.

[0020] Another object of the present invention is to provide an electrode for a proton exchange membrane fuel cell for use in a ship, wherein the electrode surface film is prepared using any of the metal alloy catalysts described above.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This study used a solvothermal method to prepare three PtNiCo ternary alloy catalysts supported by graphene oxide (GO), reduced graphene oxide (RGO), and reduced graphene oxide (RGO-SO3H) grafted with sulfonic acid groups. The PtNiCo ternary alloy structure provides a complex shape, thereby increasing the specific surface area. The sulfonic acid groups enhance the stability of the catalyst as an anchoring center for the PtNiCo ternary alloy. Pt@PtNiCo / RGO-SO3H exhibited excellent electrochemical performance for the oxygen reduction reaction under a simulated proton exchange membrane fuel cell environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0024] Figure 1 This is the X-ray powder diffraction spectrum of the catalyst prepared in Example 1 of the present invention.

[0025] Figure 2 This is a scanning electron microscope image of the catalyst prepared in Example 1 of the present invention.

[0026] Figure 3 This is a comparison chart of the CV curves of the metal alloy catalysts obtained in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0030] Example 1

[0031] (1) (NH4)2SO4 and graphene oxide (GO) were mixed in a mass ratio of 1:5 and dispersed in distilled water under ultrasonication for 30 min. The suspension was decompressed in a rotary evaporator to obtain a powder;

[0032] (2) The above powder was decomposed in a quartz tube furnace at 250 °C, wherein flowing Ar gas was introduced into the quartz tube to ensure that oxygen was isolated during the reaction process, to obtain reduced graphene oxide (RGO) grafted with -SO3H groups, named RGO-SO3H support;

[0033] (3) H2PtCl6·H2O, Co(NO3)2·6H2O and Ni(NO3)·6H2O were mixed in a metal ion atomic ratio of 1:1:1, mixed with the above-mentioned RGO-SO3H support with a metal loading of 20 wt.%, ultrasonically mixed at room temperature for 30 min, added to ethylene glycol (200 ml), and reduced at 150 °C under Ar atmosphere for 2 h to obtain a suspension of RGO-SO3H loaded PtNiCo;

[0034] (4) The suspension of PtNiCo supported on RGO-SO3H was acid-washed by adding 0.1 mol / L dilute sulfuric acid solution to remove Ni and Co elements on the surface of PtNiCo. The catalyst was then washed, filtered and dried to obtain a metal alloy catalyst supported on RGO-SO3H, named Pt@PtNiCo / RGO-SO3H catalyst.

[0035] The X-ray powder diffraction spectrum of the obtained catalyst is as follows: Figure 1 As shown in the figure, obvious diffraction peaks are shown. After comparison with the JCPDS diffraction data card, it is found that they are Pt (2θ = 39.76°, 2θ = 46.24°), PtNi (2θ = 26.12°, 2θ = 34.94°) and PtCo (2θ = 22.54°, 2θ = 26.12°, 2θ = 48.26°). It can be determined that PtNiCo exists in the form of a ternary alloy.

[0036] The scanning electron microscopy images of the obtained catalyst are shown in Figure 2 As shown in the figure, it can be seen that the size of the metal alloy catalyst nanoparticles is between 5 and 10 nm.

[0037] Among them, the surface of the metal alloy is Pt, and the interior is a core-shell structure of PtNiCo, forming a Pt@PtNiCo / RGO-SO3H catalyst.

[0038] Example 2

[0039] (1) (NH4)2SO4 and graphene oxide (GO) were mixed in a mass ratio of 1:5 and dispersed in distilled water under ultrasonication for 30 min. The suspension was decompressed in a rotary evaporator to obtain a powder;

[0040] (2) The above powder was decomposed in a quartz tube furnace at 250 °C, wherein flowing Ar gas was introduced into the quartz tube to ensure that oxygen was isolated during the reaction process, to obtain reduced graphene oxide (RGO) grafted with -SO3H groups, named RGO-SO3H support;

[0041] (3) H2PtCl6·H2O, Co(NO3)2·6H2O and Ni(NO3)·6H2O were mixed in a ratio of 1:1:1 of the number of metal ion atoms, mixed with the above-mentioned RGO-SO3H support with a metal loading of 25 wt.%, ultrasonically mixed at room temperature for 30 min, added to ethylene glycol (200 ml), and reduced at 150 °C under Ar atmosphere for 2 h to obtain a suspension of RGO-SO3H loaded PtNiCo.

[0042] (4) The suspension of PtNiCo supported on RGO-SO3H was acid-washed with 0.1 mol / L dilute sulfuric acid solution to remove Ni and Co elements on the surface of PtNiCo. The suspension was then washed, filtered, and dried to obtain a metal alloy catalyst supported on RGO-SO3H, designated Pt@PtNiCo / RGO-SO3H catalyst. The size of the resulting catalyst nanoparticles was between 20 and 30 nm.

[0043] Example 3

[0044] (1) (NH4)2SO4 and graphene oxide (GO) were mixed in a mass ratio of 1:5 and dispersed in distilled water under ultrasonication for 30 min. The suspension was decompressed in a rotary evaporator to obtain a powder;

[0045] (2) The above powder was decomposed in a quartz tube furnace at 250 °C, wherein flowing Ar gas was introduced into the quartz tube to ensure that oxygen was isolated during the reaction process, to obtain reduced graphene oxide (RGO) grafted with -SO3H groups, named RGO-SO3H support;

[0046] (3) H2PtCl6·H2O, Co(NO3)2·6H2O and Ni(NO3)·6H2O were mixed in a ratio of 1:1:1 of the number of metal ions, mixed with the above-mentioned RGO-SO3H support with a metal loading of 10 wt.%, ultrasonically mixed at room temperature for 30 min, added to ethylene glycol (200 ml), and reduced at 150 ° C under Ar atmosphere for 2 h to obtain a suspension of RGO-SO3H loaded PtNiCo;

[0047] (4) The suspension of PtNiCo supported on RGO-SO3H was acid-washed with 0.1 mol / L dilute sulfuric acid solution to remove Ni and Co elements on the surface of PtNiCo. The suspension was then washed, filtered, and dried to obtain a metal alloy catalyst supported on RGO-SO3H, designated Pt@PtNiCo / RGO-SO3H catalyst. The size of the resulting catalyst nanoparticles was between 5 and 10 nm.

[0048] Example 4

[0049] (1) (NH4)2SO4 and graphene oxide (GO) were mixed in a mass ratio of 1:5 and dispersed in distilled water under ultrasonication for 30 min. The suspension was decompressed in a rotary evaporator to obtain a powder;

[0050] (2) The above powder was decomposed in a quartz tube furnace at 250 °C, wherein flowing Ar gas was introduced into the quartz tube to ensure that oxygen was isolated during the reaction process, to obtain reduced graphene oxide (RGO) grafted with -SO3H groups, named RGO-SO3H support;

[0051] (3) H2PtCl6·H2O, Co(NO3)2·6H2O and Ni(NO3)·6H2O were mixed in a ratio of 1:1:1 of the number of metal ions, mixed with the above-mentioned RGO-SO3H support with a metal loading of 5 wt.%, ultrasonically mixed at room temperature for 30 min, added to ethylene glycol (200 ml), and reduced at 150 ° C under Ar atmosphere for 2 h to obtain a suspension of RGO-SO3H loaded PtNiCo;

[0052] (4) The suspension of PtNiCo supported on RGO-SO3H was acid-washed with 0.1 mol / L dilute sulfuric acid solution to remove Ni and Co elements on the surface of PtNiCo. The suspension was then washed, filtered, and dried to obtain a metal alloy catalyst supported on RGO-SO3H, designated Pt@PtNiCo / RGO-SO3H catalyst. The size of the resulting catalyst nanoparticles was between 5 and 10 nm.

[0053] Comparative Example 1

[0054] (1) H2PtCl6·H2O, Co(NO3)2·6H2O and Ni(NO3)·6H2O were mixed in a ratio of 1:1:1 of the number of metal ions, mixed with a graphene oxide (GO) carrier with a metal loading of 20 wt.%, ultrasonically mixed at room temperature for 30 min, added to ethylene glycol (200 ml), and reduced at 150 °C in an Ar atmosphere for 2 h to obtain a suspension of RGO loaded PtNiCo.

[0055] (2) The suspension of PtNiCo supported on RGO was acid-washed with 0.1 mol / L dilute sulfuric acid solution to remove Ni and Co elements on the surface of PtNiCo. The suspension was then washed, filtered, and dried to obtain a metal alloy catalyst supported on RGO, designated Pt@PtNiCo / RGO catalyst. The resulting catalyst nanoparticles had a size of 15 to 20 nm.

[0056] Comparative Example 2

[0057] (1) (NH4)2SO4 and graphene oxide (GO) were mixed in a ratio of 1:5 and dispersed in distilled water under ultrasonication for 30 min. The suspension was decompressed in a rotary evaporator to obtain a powder.

[0058] (2) The above powder was decomposed in a quartz tube furnace at 250 °C, wherein flowing Ar gas was introduced into the quartz tube to ensure that oxygen was isolated during the reaction process, and reduced graphene oxide (RGO) grafted with -SO3H groups was obtained, which was named RGO-SO3H support.

[0059] (3) H2PtCl6·H2O and RGO-SO3H support were mixed with the above RGO-SO3H support at a metal loading of 20 wt.%, ultrasonically mixed at room temperature for 30 min, added to ethylene glycol (200 ml), and reduced at 150 °C under Ar atmosphere for 2 h to obtain a suspension of RGO-SO3H loaded with Pt.

[0060] (4) The suspension was washed, filtered, and dried to obtain a metal catalyst on a RGO-SO3H support, named Pt / RGO-SO3H catalyst. The size of the obtained catalyst nanoparticles was between 20 and 25 nm.

[0061] Electrochemical performance test

[0062] Three conventional electrodes were used to characterize the electrochemical properties of Examples 1 to 4 and Comparative Examples 1 to 2. A platinum plate was used as a counter electrode. A Hg / Hg2Cl2 electrode was used as a reference electrode. A glassy carbon electrode (d = 3 mm) was connected to a rotating system (Princeton Applied Research, Model 636A) as a working electrode. The glassy carbon electrode was polished with 0.03 μm alumina slurry. Then, the surface of the working electrode was ultrasonically treated for 10 minutes. 1 mg of catalyst was dispersed in distilled water. The suspension was 1 mL, containing 0.1 mL of 5 wt.% Nafion solution. 20 μL of the suspension was dropwise applied to a clean glassy carbon electrode as a working electrode. After drying the electrode surface, the electrochemical measurement of the electrode was completed. Cyclic voltammetry (CV) was performed in 0.5 M H2SO4 at 10 mV·s -1 The scanning rate of the scanning rate was 10mV·s in the potential range of 0-1.0V vs.RHE at room temperature and oxygen was added for 40min to saturate the solution with oxygen. -1 The catalyst was tested for half-cell oxygen reduction reaction (ORR) at a scan rate of 1500 rpm. The durability of the catalyst was evaluated by performing 5000 cycles of CV between 0.5 V and 1.0 V (vs. RHE). After the durability test, the catalyst was tested at a scan rate of 10 mV·s -1 The CV curves of the metal alloy catalysts obtained in Example 1, Comparative Example 1 and Comparative Example 2 were compared with the initial values ​​to characterize the Pt surface activity. Figure 3 The electrochemical performance test results are shown in Table 1.

[0063] Table 1

[0064]

[0065] As can be seen from the data in Table 1, the metal alloy catalyst obtained by the present invention has a smaller particle size than the catalyst without sulfonic acid groups grafted onto the carrier (Comparative Example 1) and the catalyst without NiCo alloy added (Comparative Example 2). However, the metal loading on the reduced graphene oxide carrier grafted with sulfonic acid groups of the present invention should not be too high. When the metal loading reaches 25 wt.%, the particle size of the obtained metal alloy catalyst increases to 20 to 30 nm.

[0066] It can be seen from the data in Table 1 that only when the metal loading on the reduced graphene oxide support grafted with sulfonic acid groups of the present invention is 20 wt.%, the electrochemical performance of the obtained metal alloy catalyst is the best, and the catalytic efficiency reaches 8.2 J / mA cm -2The Pt surface area loss after 5000 cycles was only 10%. At other metal loadings, the electrochemical performance of the obtained metal alloy catalysts was not significantly different from that of the catalyst without sulfonic acid groups grafted onto the support (Comparative Example 1) and the catalyst without NiCo alloy addition (Comparative Example 2).

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a metal alloy catalyst for a proton exchange membrane fuel cell for use in ships, characterized by: (NH4)2SO4 and graphene oxide were mixed in a mass ratio of 1:5 and dispersed in distilled water under ultrasonication for 30 min. The suspension was decompressed in a rotary evaporator to obtain a powder; The powder was decomposed in a quartz tube furnace at 250°C, with flowing Ar gas passing through the quartz tube to ensure oxygen isolation during the reaction, to obtain reduced graphene oxide grafted with sulfonic acid groups, named RGO-SO3H support; H2PtCl6·H2O, Co(NO3)2·6H2O and Ni(NO3)·6H2O were mixed in a metal ion atomic ratio of 1:1:1, mixed with RGO-SO3H support with a metal loading of 20 wt.%, ultrasonically mixed at room temperature for 30 min, added to 200 ml of ethylene glycol, and reduced at 150 ° C under Ar atmosphere for 2 h to obtain a suspension of RGO-SO3H loaded PtNiCo; The suspension of PtNiCo loaded on RGO-SO3H was acid-washed by adding 0.1 mol / L dilute sulfuric acid solution to remove Ni and Co elements on the surface of PtNiCo. The suspension was then washed, filtered and dried to obtain a metal alloy catalyst on the RGO-SO3H carrier, which is a metal alloy catalyst for proton exchange membrane fuel cells for ships.

2. The metal alloy catalyst for proton exchange membrane fuel cells for ships prepared by the preparation method according to claim 1.

3. Use of the metal alloy catalyst according to claim 2 in a proton exchange membrane fuel cell for ships.

4. An electrode for a proton exchange membrane fuel cell for a ship, characterized in that: The electrode surface film is prepared using the metal alloy catalyst according to claim 2.

Images