Pt-based synergistic catalyst, preparation method and application thereof

Abstract

This invention belongs to the field of fuel cell catalytic materials technology, specifically relating to a Pt-based synergistic catalyst, its preparation method, and its application. It includes a Pt / C catalyst matrix formed by a carbon support and Pt nanoparticles supported on the carbon support. The Pt nanoparticles have poisoned atoms (A) selectively adsorbed on their surface via A-Pt bonds. The carbon support surface is supported with metal oxide nanoclusters (MO). x Metal oxide nanoclusters MO x Pt / MO forms with Pt nanoparticles, creating a reverse hydrogen overflow channel. x Interface. This invention is based on a synergistic strategy of "selectively poisoning ORR active sites" and "enhancing HOR kinetics through interfacial hydrogen spillover" to achieve specific HOR catalysis in acidic media in the traditional Pt / C system. This solves the problems of existing catalysts being unable to simultaneously achieve ORR inhibition and HOR activity, having poor compatibility, and being complex to prepare. At the same time, it has commercial feasibility, high stability, and excellent resistance to start-stop degradation.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell catalytic materials technology, specifically relating to a Pt-based synergistic catalyst, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) hold an irreplaceable core position in the field of new energy vehicles, boasting outstanding advantages such as high energy conversion efficiency, environmental friendliness, and zero noise pollution. However, insufficient durability of PEMFCs has become the ultimate bottleneck for their large-scale industrialization, with the accelerated performance degradation under start-stop conditions being the most critical issue, severely restricting the actual service life and economic viability of automotive PEMFCs.

[0003] The performance degradation of PEMFCs under start-up and shutdown conditions has a clear electrochemical mechanism: during the start-up and shutdown transients, the interruption of hydrogen supply to the anode and air intrusion are asynchronous, forming an unavoidable hydrogen-air interface. The inherent "dual-function activity" of commercial Pt / C catalysts (catalyzing both the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR)) turns from an advantage to a disaster under this abnormal environment, triggering the "reverse current" or "virtual fuel cell" effect. This causes the anode potential to jump from the steady-state 0V to 1.0-1.2V, and the cathode potential to rise simultaneously, even exceeding 1.5V. This, in turn, triggers a chain reaction of deterioration, including the electrochemical oxidation of the cathode carbon support and the shedding and aggregation of Pt particles, resulting in the cumulative degradation of the membrane electrode assembly (MEA) performance.

[0004] Currently, researchers have developed two main technical approaches to address the above problems: (1) a "symptomatic" solution for mass transfer regulation, which focuses on eliminating the hydrogen-air interface by regulating anode mass transfer. Typical technical approaches include inert gas purging, external circuit dummy load discharge, rapid anode hydrogen charging, and closed-loop hydrogen circulation control. While these solutions can alleviate start-stop degradation in the short term, they require additional equipment and control modules, leading to a significant increase in system complexity, weight, cost, and failure rate. This contradicts the industrialization requirements of automotive PEMFCs for "lightweight, low cost, and high reliability," making large-scale application difficult. (2) a "passive defense" solution for catalyst optimization: improving the corrosion resistance of cathode catalysts through Pt alloying, carbon support modification and graphitization, and interface strengthening. While these studies have made some progress in improving material stability, they have not addressed the core contradiction of the problem—they focus on making the catalyst resistant to high-potential cathode impacts rather than preventing such impacts from the source. As long as the Pt / C catalyst maintains ORR activity, the potential spike caused by the start-stop hydrogen-air interface is inevitable and the start-stop degradation problem cannot be fundamentally solved. Summary of the Invention

[0005] The purpose of this invention is to provide a Pt-based synergistic catalyst for resisting start-stop degradation in proton exchange membrane fuel cells, along with its preparation method and application. Through a synergistic strategy of "selectively poisoning ORR active sites" and "enhancing HOR kinetics through interfacial hydrogen overflow," specific HOR catalysis in acidic media is achieved in the traditional Pt / C system, eliminating potential spikes under start-stop conditions from the source. This addresses the problems of existing catalysts being unable to simultaneously achieve ORR inhibition and HOR activity, having poor compatibility, and being complex to prepare. Furthermore, it possesses commercial feasibility, high stability, and excellent resistance to start-stop degradation.

[0006] To achieve the above objectives, the specific technical solution provided by the present invention is as follows: The first objective of this invention is a Pt-based synergistic catalyst, comprising a carbon support and a Pt / C catalyst matrix formed by Pt nanoparticles supported on the carbon support. The surface of the Pt nanoparticles is selectively adsorbed with poisoning atoms A via A-Pt bonds to poison the active sites on the Pt nanoparticle surface. The coverage of the poisoning atoms is 0.1 to 0.5 monolayers. The carbon support surface is supported with metal oxide nanoclusters MO. x Metal oxide nanoclusters MO x Pt / MO forms with Pt nanoparticles, creating a reverse hydrogen overflow channel. x The interface, where the M atom is at least one of W, Mo, Ce or Mn.

[0007] Furthermore, the metal oxide nanocluster structure MO x The loading amount is 5wt% to 20wt% of the mass of Pt nanoparticles, and the metal oxide nanocluster structure MO x The particle size is 2nm to 3nm.

[0008] Furthermore, the poisoning atom A is one or both of S and P atoms; when the poisoning atom A is both S and P atoms, the molar ratio of S atoms to P atoms is 1:0.5 to 2.

[0009] Furthermore, in the Pt / C catalyst matrix, the loading of Pt nanoparticles is 20wt% to 50wt%, and the particle size of the Pt nanoparticles is 2nm to 5nm.

[0010] Furthermore, the carbon support is at least one of Vulcan XC-72, EC-300J, and carbon nanotubes, with a specific surface area of ​​200 m². 2 / g~1000m 2 / g, with a pore size of 2nm to 50nm.

[0011] A second objective of this invention is to provide a method for preparing the above-mentioned Pt-based synergistic catalyst, comprising the following steps: S1. Under a protective atmosphere, using Pt / C catalyst matrix as raw material and hydride containing poisoned A atoms as precursor, vapor deposition is performed to selectively adsorb A atoms onto the surface of Pt nanoparticles. Subsequently, annealing is performed to induce A atoms to migrate or reconstruct from the Pt surface, thus obtaining the A-Pt / C intermediate.

[0012] S2. Using a metal salt containing M atoms as a precursor solution, the A-Pt / C intermediate is immersed in the precursor solution by impregnation, followed by stirring and adsorption. Then, a reducing agent is added, and stirring continues to reduce the precursor to MO on the carbon support surface. x Nanoclusters, MO x Nanoclusters and Pt nanoparticles form Pt / MO x The interface provides the load MO. x The intermediate.

[0013] S3. Under a protective atmosphere or a protective atmosphere containing 5%–10% H2 by volume, load the MO x The intermediate was calcined to obtain a Pt-based synergistic catalyst.

[0014] Furthermore, the vapor deposition temperature is 150℃~200℃, the time is 10min~30min, the annealing temperature is 200℃~300℃, the annealing time is 1h~2h, and the annealing atmosphere is an inert gas or an inert gas containing 5%~10% H2 by volume.

[0015] Furthermore, the concentration of the precursor solution is 0.01 mol / L to 0.05 mol / L, the temperature for stirring and adsorption is 25℃ to 60℃, and the molar ratio of reducing agent to precursor is 2 to 5:1.

[0016] Furthermore, the calcination temperature is 300℃~400℃, the time is 2h~3h, and the heating rate is 5℃ / min~10℃ / min.

[0017] A third objective of this invention is to provide the application of the aforementioned Pt-based synergistic catalyst as an anode catalyst in proton exchange membrane fuel cells.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The Pt-based synergistic catalyst provided by this invention utilizes a dual-mechanism synergistic regulation of "selective poisoning of ORR active sites" and "interfacial hydrogen spillover enhancing HOR kinetics." Using a commercially available Pt / C catalyst matrix, poisoning atoms A are selectively adsorbed onto specific active sites on the surface of Pt nanoparticles to selectively poison the ORR active sites. By regulating the d-band electronic structure of Pt, the ORR reaction pathway is blocked, while simultaneously preserving the appropriate adsorption strength of Pt for H*, thus providing a foundation for the HOR reaction. Secondly, MO forms a tight interface with the Pt nanoparticles on the carbon support surface. x Nanocluster structures are used to construct reverse hydrogen overflow channels, achieving efficient compensation and enhancement of HOR activity through the reverse hydrogen overflow effect. This addresses the potential impact of S / P atom poisoning on HOR activity and alleviates the hydrogen depletion problem during start-up and shutdown. Furthermore, it involves poisoning atoms A and MO. x The synergistic effect of nanoclusters achieves a dynamic balance of "oxygen suppression and hydrogen promotion", enabling the catalyst to maintain high HOR activity during normal hydrogen supply operation and completely suppress the ORR pathway when the start-stop hydrogen-vacancy interface is formed, thus avoiding potential spikes.

[0019] This invention employs a combined vapor-phase deposition and liquid-phase deposition approach. Through precise site-selective poisoning, it poisons only the ORR active sites on the Pt surface, maximizing the preservation of HOR activity and ensuring that the rated power output of the fuel cell is not affected during normal operation. This achieves a balance between start-stop stability and normal power generation performance. The fabrication process is simple, cost-controllable, and easy to scale up industrially. Furthermore, the fabrication process is compatible with existing membrane electrode coating and assembly processes, requiring no modifications to existing production lines, and enabling rapid industrial production and application. Attached Figure Description

[0020] Figure 1 S-Pt / WO prepared in Example 1 of this invention x X-ray photoelectron spectroscopy of the -C co-catalyst. Figure 1 In the diagram, a is the S 2p spectrum, b is the O 1s spectrum, c is the W 4f spectrum, and d is the Pt 4f spectrum.

[0021] Figure 2 P-Pt / MoO prepared in Example 2 of this invention x X-ray photoelectron spectroscopy of the -C co-catalyst Figure 2 In the diagram, a is the P 2p spectrum, b is the O 1s spectrum, c is the Mo 3d spectrum, and d is the Pt 4f spectrum.

[0022] Figure 3 SP-Pt / (CeO) prepared in Example 3 of this invention x -MnO x X-ray photoelectron spectroscopy of the )-C co-catalyst, Figure 3 In the diagram, a is the S 2p spectrum, b is the P 2p spectrum, c is the O 1s spectrum, d is the Ce 3d spectrum, e is the Mn 2p spectrum, and f is the Pt 4f spectrum.

[0023] Figure 4 The above diagram shows the comparison of cathode potentials of PEMFCs assembled from the catalysts of Examples 1 to 3 and Comparative Example 1 under start-up and shutdown conditions.

[0024] Figure 5 This is a comparison of the cathode potentials under start-stop conditions after 500 start-stop cycles of the catalysts assembled into PEMFCs in Examples 1 to 3 and Comparative Example 1 of the present invention.

[0025] Figure 6 The above chart shows the hydrogen-air performance of PEMFC assembled with the catalysts of Examples 1 to 3 and Comparative Example 1 under normal operating conditions with sufficient hydrogen supply.

[0026] Figure 7 The graph shows the hydrogen-air performance of the catalysts assembled into PEMFCs in Examples 1 to 3 and Comparative Example 1 of this invention after 500 start-stop cycles under normal operating conditions with sufficient hydrogen supply.

[0027] Figure 8 The images show the cathode catalyst structure characterization diagrams after 500 start-stop cycles of the catalysts from Example 1 and Comparative Example 1 assembled into a PEMFC. Figure 8 In the text, a represents Comparative Example 1, and b represents Example 1. Detailed Implementation

[0028] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Commercial Pt / C catalysts, due to their d-band electronic structure, exhibit suitable adsorption of intermediates in both the hydrogen-oxygen reduction (HOR) and oxygen reduction (ORR) reactions. This leads to an inherent bifunctional activity at the hydrogen-air interface, triggering a "reverse current" effect. This forces the anode potential to surge to 1.0–1.2 V and the cathode potential to exceed 1.5 V, subsequently inducing carbon support oxidation and Pt particle agglomeration, resulting in irreversible degradation of membrane electrode performance. Existing technological approaches to address this core challenge of start-stop degradation have fundamental limitations: while mass transfer control schemes can alleviate degradation by eliminating the HOR interface, the added complexity of equipment and control systems contradicts the lightweight and low-cost requirements of automotive fuel cells; catalyst optimization focuses on improving the corrosion resistance of the cathode material, a passive defense approach that cannot prevent potential spikes at the source as long as Pt / C retains ORR activity.

[0031] Therefore, the key to overcoming the start-stop degradation of PEMFCs lies not in seeking more corrosion-resistant bifunctional catalysts, but in designing "quasi-monofunctional" catalysts that can intelligently distinguish reaction environments and selectively perform HOR (Heat-Off Rise) only at the start-stop hydrogen-air interface. Thus, within an acidic environment and a commercially viable Pt / C system framework, achieving specific catalysis of HOR to eliminate start-stop potential spikes at the source has become a core technical problem urgently needing to be solved in the current PEMFC field, and a key breakthrough for promoting the large-scale industrialization of PEMFCs.

[0032] This invention, based on the intrinsic catalytic characteristics of the anode catalyst, selectively poisons the ORR active sites and constructs a reverse hydrogen overflow channel, fundamentally blocking the ORR reaction and potential rise after the formation of the anode hydrogen-vacuum interface. This achieves "active protection," unlike the "passive protection" of existing technologies, and completely prevents the cathode potential from exceeding 1.5V, fundamentally solving the core problem of PEMFC start-up and shutdown degradation. Specifically:

[0033] A Pt-based synergistic catalyst comprises a carbon support and a Pt / C catalyst matrix formed by Pt nanoparticles supported on the carbon support. The Pt nanoparticles have selectively adsorbed poisoning atoms (A) via A-Pt bonds on their surface to poison the active sites. The coverage of the poisoning atoms is 0.1 to 0.5 monolayers. The carbon support surface is supported with metal oxide nanoclusters (MO). x Metal oxide nanoclusters MO x Pt / MO forms with Pt nanoparticles, creating a reverse hydrogen overflow channel. x The interface, where the M atom is at least one of W, Mo, Ce or Mn.

[0034] The Pt / C catalyst matrix used in this invention is a commercially available Pt / C catalyst. A Pt-based synergistic catalyst is obtained through selective poisoning and interfacial modification of the commercial Pt / C catalyst. First, poisoning atoms A at specific active sites are selectively adsorbed on the surface of Pt nanoparticles to selectively poison the ORR active sites on the Pt nanoparticle surface. By regulating the d-band electronic structure of Pt, the ORR reaction pathway is blocked, while retaining the appropriate adsorption strength of Pt for H*, providing a basis for the HOR reaction. Second, MO forms a tight interface with the Pt nanoparticles on the carbon support surface. x Nanocluster structures are used to construct reverse hydrogen overflow channels, achieving efficient compensation and enhancement of HOR activity through the reverse hydrogen overflow effect. This addresses the potential impact of S / P atom poisoning on HOR activity and alleviates the hydrogen depletion problem during start-up and shutdown. Furthermore, it involves poisoning atoms A and MO. x The synergistic effect of nanoclusters achieves a dynamic balance of "oxygen suppression and hydrogen promotion", enabling the catalyst to maintain high HOR activity during normal hydrogen supply operation and completely suppress the ORR pathway when the start-stop hydrogen-vacancy interface is formed, thus avoiding potential spikes.

[0035] In some embodiments, the loading of Pt nanoparticles in the Pt / C catalyst matrix is ​​20wt%–50wt%, the particle size of the Pt nanoparticles is 2nm–5nm, and the metal oxide nanoclusters MO x The loading amount is 5wt% to 20wt% of the mass of Pt nanoparticles. As a preferred embodiment of the present invention, the metal oxide nanoclusters MO x The loading amount is 10wt% to 15t of Pt nanoparticles, and the metal oxide nanoclusters MO x The particle size is 2nm to 3nm. In this invention, the nanoclusters MO x The structure is uniformly dispersed on the surface of the carbon support, forming a tight Pt / MO structure with the Pt nanoparticles. x Interface for constructing an efficient reverse hydrogen overflow channel.

[0036] In some embodiments, the poisoning atom A is one or both of S and P atoms. In this invention, the poisoning atom A is selectively adsorbed on the high-index crystal plane (such as the Pt(211) crystal plane) of Pt nanoparticles and is bound to the Pt nanoparticles through A-Pt bonds. The high thermodynamic stability of the A-Pt bonds ensures the persistence of the poisoning effect under high-potential transients during start-up and shutdown. In the preferred embodiment of this invention, the coverage of the poisoning atom A is 0.1 to 0.5 monolayers. When the poisoning atom A is S and P atoms, the molar ratio of S atoms to P atoms is 1:0.5 to 2, which can further optimize the ORR activity inhibition effect and improve the stability of HOR activity.

[0037] This invention achieves specific HOR catalysis of Pt-based catalysts in acidic media through the synergistic regulation of a dual mechanism: selective poisoning of ORR active sites and enhanced HOR kinetics through interfacial hydrogen spillover. The core synergistic mechanism is as follows: (1) S / P atom precise poisoning to break ORR activity: S atoms selectively adsorb on the high-index surface (ORR active site) of Pt nanoparticles. Through the formation of S-Pt bonds, the center of the d-band of Pt is significantly moved upward, specifically enhancing the excessive adsorption of ORR intermediates, making it difficult for these intermediates to be further reduced or desorbed, thus blocking the ORR reaction pathway from both thermodynamic and kinetic perspectives. At the same time, by controlling the coverage and local coordination environment of S, the appropriate adsorption strength of Pt for H* is preserved to the maximum extent, laying the foundation for subsequent hydrogen spillover compensation. In addition, the high thermodynamic stability of S-Pt bonds ensures the persistence of the poisoning effect under the high-potential transient of start-stop, avoiding the recovery of ORR activity caused by the desorption of S / P atoms.

[0038] (2) MO x Induced reverse hydrogen overflow compensation and enhanced HOR activity: MOx nanostructures possess strong proton (H) content. + The affinity and local enrichment ability of MO can create a proton-rich microenvironment on the carbon support surface, providing favorable conditions for the adsorption and dissociation of hydrogen species; at the same time, MO x It can itself serve as a highly efficient hydrogen overflow "starter." Its unique electronic structure weakens HH bonds, promoting heterolytic dissociation of H2 on the carbon support surface to generate reactive H species, providing a sufficient hydrogen source for the HOR reaction. More importantly, in Pt / MO... x The reverse hydrogen overflow channel formed at the interface can transfer MO x The H species generated by surface dissociation are rapidly and directionally transported to nearby Pt active sites, effectively compensating for the potential impact of S atom poisoning on HOR activity and enhancing HOR reaction kinetics.

[0039] (3) Synergistic balance of "Oxygen suppression and hydrogen promotion": The S poisoning site and the hydrogen overflow network form a dynamic synergistic effect. During normal hydrogen supply operation, the hydrogen overflow network continuously delivers H species to the Pt surface, maintaining a high Pt-H coverage and ensuring excellent HOR activity. At this time, the S poisoning site is in a "silent" state and does not affect normal operation. During the start-up and shutdown crisis, the hydrogen supply is interrupted and the anode hydrogen-vacuum interface is formed. At this time, the "hydrogen buffer" provided by the hydrogen overflow network can effectively slow down the rate of anode potential rise. At the same time, the pre-constructed S poisoning site resolutely "rejects oxygen" and completely inhibits the start-up of ORR. The synergy of the two provides a double guarantee for stabilizing the anode potential in the low potential range within the critical time window, realizing the intelligent adaptive switching of catalyst function with changes in the reaction environment, eliminating the surge in start-up and shutdown potentials from the source, and avoiding the occurrence of chain deterioration reactions.

[0040] In some embodiments, the carbon support is at least one of Vulcan XC-72, EC-300J, and carbon nanotubes, with a specific surface area of ​​200 m². 2 / g~1000m 2 / g, with a pore size of 2nm~50nm. This ensures the compatibility of Pt nanoparticles with MO. x Uniform dispersion and efficient mass transfer of nanoclusters.

[0041] In addition, the present invention also provides a method for preparing the above-mentioned Pt-based synergistic catalyst, comprising the following steps: S1. Under a protective atmosphere, using Pt / C catalyst matrix as raw material and hydride containing poisoned A atoms as precursor, vapor deposition is performed to selectively adsorb A atoms onto the surface of Pt nanoparticles. Subsequently, annealing is performed to induce A atoms to migrate or reconstruct from the Pt surface, thus obtaining the A-Pt / C intermediate.

[0042] In this invention, the hydrides containing poisoning atom A are H2S and H3P, but under an inert atmosphere (Ar) protection, they are deposited onto a Pt / C catalyst. The vapor deposition temperature is 150℃~200℃ and the time is 10min~30min, achieving the initial adsorption of S / P atoms on the surface of Pt nanoparticles. Subsequently, annealing is performed under an inert gas (Ar) or an inert gas containing 5%~10% H2 by volume, inducing the migration or reconstruction of S / P atoms from the Pt surface, achieving the directional modulation of S / P atom coverage and local coordination environment. The annealing temperature is 200℃~300℃ and the annealing time is 1h~2h.

[0043] S2. Using a metal salt containing M atoms as a precursor solution, the A-Pt / C intermediate is immersed in the precursor solution by impregnation, followed by stirring and adsorption. Then, a reducing agent is added, and stirring continues to reduce the precursor to MO on the carbon support surface. x Nanoclusters, MO x Nanoclusters and Pt nanoparticles form Pt / MO x The interface provides the load MO. x The intermediate.

[0044] In this invention, the metal salt is a nitrate, and the concentration of the precursor solution is 0.01 mol / L to 0.05 mol / L. M is one or more of W, Mo, Ce, and Mn. x When the mixture is a mixture of multiple metal oxides, the corresponding multiple metal nitrates can be mixed in a preset ratio to prepare a mixed precursor solution, and the remaining operations remain unchanged to achieve multiple MOs. x Collaborative load.

[0045] In this invention, liquid-phase deposition is employed. The A-Pt / C intermediate is immersed in a precursor solution and adsorbed by stirring at 25°C to 60°C for 1 to 3 hours at a stirring rate of 200 to 500 r / min. Then, a reducing agent is added, with a molar ratio of reducing agent to precursor of 2 to 5:1. The reducing agent is sodium borohydride or ascorbic acid, which reduces the precursor to MO on the carbon support surface. x Nanoclusters; the sample was then centrifuged (5000-8000 rpm, 5-10 min), and washed alternately with anhydrous ethanol and deionized water 3-5 times to remove unreacted precursors and reducing agents, yielding MO-loaded nanoclusters. x The intermediate, at this time MO x Uniformly dispersed on the surface of the carbon support, and forming a tight Pt / MO structure with Pt nanoparticles. x interface.

[0046] S3. Under a protective atmosphere or a protective atmosphere containing 5%–10% H2 by volume, load the MO x The intermediate was placed in a tube furnace and calcined. The calcination temperature was controlled at 300℃~400℃, the calcination time was 2~3h, and the heating rate was 5℃ / min~10℃ / min. This further enhanced the bonding between S / P atoms and Pt, the interfacial interaction between MOx and carbon support and Pt, and removed residual impurities to obtain a Pt-based synergistic catalyst.

[0047] This invention employs a combined vapor-phase deposition and liquid-phase deposition method to achieve precise poisoning of S / P atoms and MO on a commercial Pt / C catalyst substrate. x The nanostructured interface construction, through precise site-selective poisoning, poisons only the ORR active sites on the Pt surface, maximizing the preservation of HOR activity and ensuring that the rated power output of the fuel cell remains unaffected during normal operation, achieving a balance between start-stop stability and normal power generation performance. The catalyst of this invention is based on commercially available Pt / C modification, with a simple, convenient, and mild preparation process that requires no complex equipment or high costs. Furthermore, the preparation process is compatible with existing membrane electrode coating and assembly processes, requiring no modification to existing production lines and enabling rapid industrial production and application.

[0048] This invention also provides the application of the above-mentioned Pt-based synergistic catalyst as an anode catalyst in a proton exchange membrane fuel cell. It includes the following steps:

[0049] Pt-based co-catalysts were mixed with ionomers (Nafion solution, 5%–10% by mass), and anhydrous ethanol was added. The mass ratio of co-catalyst, ionomer, and anhydrous ethanol was 1:0.2–0.5:2–5. The mixture was ultrasonically dispersed for 30–60 min to obtain a uniform anodic catalyst slurry. The anodic catalyst slurry was then sprayed onto the surface of carbon paper, with the spraying amount controlled at 0.1 mg Pt / cm². 2 ~0.3mg Pt / cm 2 The anode catalyst layer is then dried at 80℃~100℃ for 1h~2h to obtain the anodic catalyst layer. The anodic catalyst layer is then combined with a commercially available cathode catalyst layer (such as a Pt / C cathode catalyst with a loading of 0.3 mg Pt / cm³). 2 ~0.5mg Pt / cm 2 The membrane electrode assembly (MEA) is formed by assembling proton exchange membranes (Nafion 211, Nafion 212, etc.) at an assembly pressure of 1MPa to 3MPa, an assembly temperature of 120℃ to 160℃, and an assembly time of 3min to 5min. The MEA is then assembled with bipolar plates, sealing rings, and other components to form a proton exchange membrane fuel cell for use in new energy vehicles, portable power supplies, and other fields.

[0050] When the proton exchange membrane fuel cell is running under start-stop conditions, the cathode potential can be stably controlled below 0.8V; after ≥500 start-stop cycles, the cathode potential is 0.83V; under normal operating conditions (with sufficient hydrogen supply), its battery activity is comparable to that of commercial Pt / C catalysts, meeting the normal power generation requirements of PEMFC.

[0051] The following specific examples will provide further explanation.

[0052] Example 1 A Pt-based synergistic catalyst, using a commercial Pt / C catalyst as the matrix, wherein the loading of Pt nanoparticles is 50 wt%, the Pt particle size is 3 nm to 4 nm, the carbon support is Ketjenblack EC-300J, S atoms are used as poisoning atoms, and WO3 is used as the carbon support. x Hydrogen spillover promotes the structure; the S atom coverage on the Pt nanoparticle surface is a 0.2 monolayer, WO x The particle size is 2nm to 3nm, and the loading is 10wt% of the Pt mass.

[0053] The preparation method of the above-mentioned Pt-based synergistic catalyst includes the following steps: Step 1, S atom-selective poisoning: 1g of commercial Pt / C was placed in a vapor deposition apparatus, with H2S as the precursor at a flow rate of 10 sccm, under Ar atmosphere (flow rate 80 sccm) protection, and deposited at 180℃ for 20 min; subsequently, it was annealed at 250℃ for 1.5 h in Ar atmosphere to obtain the S-Pt / C intermediate.

[0054] Step 2, WO x Nanostructured interface construction: Using W(NO3)6 as a precursor, a 0.03 mol / L precursor solution was prepared. The S-Pt / C intermediate was immersed in the solution and adsorbed by stirring at 40 °C for 2 h (stirring rate 300 r / min). Subsequently, a 0.1 mol / L sodium borohydride solution was added, with a molar ratio of sodium borohydride to W(NO3)6 of 3:1, and stirring was continued for 0.5 h. Then, centrifugation was performed (7000 r / min, 8 min), and the mixture was washed four times alternately with anhydrous ethanol and deionized water to obtain the WO3-loaded interface. x The intermediate.

[0055] Step 3, Post-processing: [The text appears to be incomplete and contains several typos. A more accurate translation would x The intermediate was placed in a tube furnace under Ar atmosphere protection and heated to 350°C at a heating rate of 8°C / min, and calcined for 2.5 h to obtain the Pt-based co-catalyst, named S-Pt / WO. x -C synergistic catalyst.

[0056] Example 2 A Pt-based synergistic catalyst, using a commercially available Pt / C catalyst as the matrix, wherein the loading of Pt nanoparticles is 20 wt%, the Pt particle size is 2 nm to 3 nm, the carbon support is Vulcan XC-72, P atoms are used as poisoning atoms, and MoO is used. x Hydrogen spillover promotes the structure; the coverage of P atoms on the surface of Pt nanoparticles is a 0.3 monolayer, MoO x The particle size is 2nm to 3nm, and the loading is 15wt% of the Pt mass.

[0057] The preparation method of the above-mentioned Pt-based synergistic catalyst includes the following steps: Step 1, P atom selective poisoning: 1g of commercial Pt / C was placed in a vapor deposition apparatus, using H3P as a precursor at a flow rate of 8sccm, under Ar atmosphere protection (flow rate of 60sccm), and deposited at 150℃ for 30min; subsequently, it was annealed at 200℃ for 2h in an H2 / Ar atmosphere (H2 to Ar volume ratio of 5:95, H2 flow rate of 8sccm, Ar flow rate of 72sccm) to obtain the P-Pt / C intermediate.

[0058] Step 2, MoO xNanostructured interface construction: Using Mo(NO3)5 as a precursor, a 0.05 mol / L precursor solution was prepared. The P-Pt / C intermediate was immersed in the solution and adsorbed by stirring at 60 °C for 1 h (stirring rate 500 r / min). Subsequently, a 0.1 mol / L ascorbic acid solution was added, with a molar ratio of ascorbic acid to Mo(NO3)5 of 5:1, and stirring was continued for 1 h. Then, centrifugation was performed (8000 r / min, 5 min), and the mixture was washed 5 times alternately with anhydrous ethanol and deionized water to obtain the loaded MoO2. x The intermediate.

[0059] Step 3, Post-processing: The above MoO x The intermediate was placed in a tube furnace and calcined at 300°C for 3 hours under an H2 / Ar atmosphere (H2 to Ar volume ratio of 5:95) at a heating rate of 5°C / min to obtain a Pt-based co-catalyst, named P-Pt / MoO. x -C synergistic catalyst.

[0060] Example 3 A Pt-based synergistic catalyst, using a commercially available Pt / C catalyst as the matrix, wherein the loading of Pt nanoparticles is 30 wt%, the Pt particle size is 4 nm to 5 nm, the carbon support is Ketjenblack EC-300J, S and P atoms are poisoning atoms, the molar ratio of S to P is 1:1, and CeO is used. x and MnO x CeO is a hydrogen overflow promoting structure. x and MnO x The mass ratio is 1:1; the total coverage of S and P atoms on the surface of Pt nanoparticles is 0.4 monolayer, mixed with CeO x and MnO x The particle size is 2nm to 3nm, and the total loading is 10wt% of the Pt mass.

[0061] The preparation method of the above-mentioned Pt-based synergistic catalyst includes the following steps: Step 1, S and P atom-selective poisoning: 1g of commercial Pt / C was placed in a vapor deposition apparatus, with H2S and H3P as precursors, both at a flow rate of 5 sccm, under Ar atmosphere (flow rate 100 sccm), and deposited at 200℃ for 10 min; subsequently, it was annealed at 300℃ for 1 h in Ar atmosphere to obtain SP-Pt / C intermediate.

[0062] Step 2, mix CeO x and MnO xNanostructured interface construction: Using Ce(NO3)3 and Mn(NO3)2 as precursors, a 0.01 mol / L mixed precursor solution was prepared by mixing them at a mass ratio of 1:1. The SP-Pt / C intermediate was immersed in the solution and adsorbed by stirring at 25 °C for 3 h (stirring rate 200 r / min). Subsequently, a 0.05 mol / L sodium borohydride solution was added, with a molar ratio of sodium borohydride to the mixed precursors of 2:1, and stirring was continued for 0.5 h. Then, centrifugation was performed (5000 r / min, 10 min), and the mixture was washed four times alternately with anhydrous ethanol and deionized water to obtain the loaded mixed MO. x The intermediate.

[0063] Step 3, Post-processing: The above mixed MO x The intermediate was placed in a tube furnace under Ar atmosphere protection and heated to 400℃ at a heating rate of 10℃ / min, and calcined for 2 hours to obtain a Pt-based co-catalyst, named SP-Pt / (CeO2). x -MnO x )-C synergistic catalyst.

[0064] Comparative Example 1 A commercial Pt / C catalyst with a Pt loading of 30 wt%, Pt particle size of 3 nm to 4 nm, and Vulcan XC-72 carbon support.

[0065] The catalysts from Examples 1 to 3 and Comparative Example 1 were used as anode catalysts in proton exchange membrane fuel cells.

[0066] Weigh 0.5g of the S-Pt / WO prepared in Example 1. x -C co-catalyst or Comparative Example 1 commercial Pt / C catalyst was mixed with 0.2 g of Nafion solution (5% by mass) and 1.5 g of anhydrous ethanol, and ultrasonically dispersed at 150 W for 40 min to obtain an anode catalyst slurry; the slurry was sprayed onto carbon paper at a coating amount of 0.2 mg Pt / cm 2 The anode catalyst layer was obtained by drying at 90℃ for 1.5 h. The anode catalyst layer was then combined with a commercial Pt / C cathode catalyst layer (with a loading of 0.4 mg Pt / cm³). 2 Nafion 211 proton exchange membranes were assembled into MEAs (assembly pressure 2MPa, assembly temperature 140℃ for 4min), and then assembled into PEMFCs.

[0067] Weigh 0.5g of the P-Pt / MoO prepared in Example 2 x-C catalyst was mixed with 0.1 g of Nafion solution (10% by mass) and 2 g of anhydrous ethanol, and ultrasonically dispersed at 100 W for 60 min. 0.005 g of polyethylene glycol (dispersant) was added and stirred until homogeneous to obtain the anode catalyst slurry. The slurry was then sprayed onto carbon paper at a coating density of 0.1 mg Pt / cm². 2 The anode catalyst layer was obtained by drying at 80℃ for 2 hours. The anode catalyst layer was then combined with a commercial Pt / C cathode catalyst layer (with a loading of 0.3 mg Pt / cm³). 2 Nafion 212 proton exchange membranes were assembled into MEAs (assembly pressure 1 MPa, 120℃ assembly for 5 min), and then assembled into PEMFCs.

[0068] Weigh 0.5g of SP-Pt / (CeO) prepared in Example 3 x -MnO x The α-C catalyst was mixed with 0.25 g of Nafion solution (8% by mass) and 1 g of anhydrous ethanol, and ultrasonically dispersed at 200 W for 30 min to obtain an anode catalyst slurry. The slurry was then sprayed onto carbon paper at a coating amount of 0.3 mg Pt / cm². 2 The anode catalyst layer was obtained by drying at 100℃ for 1 hour; the anode catalyst layer was then combined with a commercial Pt / C cathode catalyst layer (with a loading of 0.5 mg Pt / cm³). 2 Nafion 211 proton exchange membranes were assembled into MEAs (assembly pressure 3MPa, assembly temperature 160℃ for 3min), and then assembled into PEMFCs.

[0069] The Pt-based synergistic catalysts prepared in Examples 1 to 3 were structurally characterized, as follows: Figures 1 to 3 As shown.

[0070] Figure 1 S-Pt / WO prepared in Example 1 of this invention x X-ray photoelectron spectroscopy of the -C co-catalyst. Figure 1 In the diagram, a is the S 2p spectrum, b is the O 1s spectrum, c is the W 4f spectrum, and d is the Pt 4f spectrum. For example... Figure 1 As shown, this confirms that S atoms were successfully adsorbed onto the Pt surface, and WO3... x The nanoclusters are effectively loaded with Pt, W, O, and S elements, all existing in the target chemical states.

[0071] Figure 2 P-Pt / MoO prepared in Example 2 of this invention x X-ray photoelectron spectroscopy of the -C co-catalyst Figure 2 In the diagram, a represents the P 2p spectrum, b represents the O 1s spectrum, c represents the Mo 3d spectrum, and d represents the Pt 4f spectrum. For example... Figure 2As shown, this confirms that P atoms were successfully modified onto the Pt surface, and MoO x The nanoclusters are stably loaded, and the characteristic peaks of Pt, Mo, O, and P elements are consistent with the designed structure.

[0072] Figure 3 SP-Pt / (CeO) prepared in Example 3 of this invention x -MnO x X-ray photoelectron spectroscopy of the )-C co-catalyst, Figure 3 In the diagram, a represents the S 2p spectrum, b represents the P 2p spectrum, c represents the O 1s spectrum, d represents the Ce 3d spectrum, e represents the Mn 2p spectrum, and f represents the Pt 4f spectrum. For example... Figure 3 As shown, the co-modification of S and P atoms was successfully confirmed, and CeO x With MnO x Bimetallic oxide co-supported catalyst with matching chemical states of each element to form a synergistic catalyst structure.

[0073] The performance of the PEMFC prepared above was tested, such as... Figures 4 to 8 As shown.

[0074] Figure 4 This is a comparison of the cathode potentials of the catalysts assembled into PEMFCs in Examples 1-3 and Comparative Example 1 under start-up and shutdown conditions. Figure 4 As shown, the performance of the PEMFC prepared above was tested. During start-up and shutdown operation, the cathode potential can be stably maintained in the range of 0.7V to 0.8V.

[0075] Figure 5 This is a comparison of the cathode potentials under start-stop conditions after 500 start-stop cycles of the catalysts assembled into PEMFCs in Examples 1 to 3 and Comparative Example 1 of the present invention. Figure 6 The above chart shows the hydrogen-air performance of PEMFC assembled with the catalysts of Examples 1 to 3 and Comparative Example 1 under normal operating conditions with sufficient hydrogen supply. Figure 7 This is a comparison chart showing the hydrogen-air performance of the catalysts from Examples 1-3 and Comparative Example 1 assembled into PEMFCs after 500 start-stop cycles under normal operating conditions with sufficient hydrogen supply. Figures 5 to 7 As shown, the catalysts from Examples 1 to 3, assembled into a PEMFC, maintained a cathode potential below 0.83V after 500 start-stop cycles, demonstrating significantly superior durability compared to commercial Pt / C catalysts. After 500 start-stop cycles, under normal operating conditions with sufficient hydrogen supply, single-cell performance showed some degradation, but remained far superior to Comparative Example 1. Compared to commercial Pt / C anode catalysts, the Pt-based synergistic catalyst of this invention effectively suppresses cathode potential spikes under start-stop conditions, significantly improving MEA stability and highlighting the superiority of the "selective poisoning-reverse hydrogen overflow" synergistic strategy of this invention.

[0076] Figure 8 The images show the cathode catalyst structure characterization diagrams after 500 start-stop cycles of the catalysts from Example 1 and Comparative Example 1 assembled into a PEMFC. Figure 8 In the text, a represents Comparative Example 1, and b represents Example 1. Figure 8 As shown, in Comparative Example 1, the Pt nanoparticles exhibited severe agglomeration, accompanied by significant particle detachment and carbon support corrosion; while in Example 1, the Pt nanoparticles were uniformly distributed on the carbon support surface without significant detachment, and the carbon support structure remained intact.

[0077] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A Pt-based co-catalyst, characterized in that, Pt-based co-catalysts comprise a Pt / C catalyst matrix consisting of a carbon support and Pt nanoparticles supported on the carbon support. The Pt nanoparticles have selectively adsorbed poisoning atoms (A) via A-Pt bonds on their surface, which poison the active sites on the Pt nanoparticle surface. The coverage of the poisoning atoms is 0.1 to 0.5 monolayers. The carbon support surface is supported with metal oxide nanoclusters (MO). x Metal oxide nanoclusters MO x Pt / MO forms with Pt nanoparticles, creating a reverse hydrogen overflow channel. x The interface, where the M atom is at least one of W, Mo, Ce or Mn.

2. The Pt-based synergistic catalyst according to claim 1, characterized in that, Metal oxide nanocluster structure MO x The loading amount is 5wt% to 20wt% of the mass of Pt nanoparticles, and the metal oxide nanocluster structure MO x The particle size is 2nm to 3nm.

3. The Pt-based synergistic catalyst according to claim 1, characterized in that, The poisoning atom A is one or both of S and P atoms; when the poisoning atom A is both S and P atoms, the molar ratio of S atoms to P atoms is 1:0.5 to 2.

4. The Pt-based synergistic catalyst according to claim 1, characterized in that, In the Pt / C catalyst matrix, the loading of Pt nanoparticles is 20wt% to 50wt%, and the particle size of Pt nanoparticles is 2nm to 5nm.

5. The Pt-based synergistic catalyst according to claim 1, characterized in that, The carbon support is at least one of Vulcan XC-72, EC-300J, and carbon nanotubes, with a specific surface area of ​​200 m². 2 / g~1000m 2 / g, with a pore size of 2nm to 50nm.

6. A method for preparing a Pt-based synergistic catalyst according to any one of claims 1 to 5, characterized in that, Includes the following steps: Under a protective atmosphere, using a Pt / C catalyst matrix as raw material and a hydride containing poisoned A atoms as a precursor, vapor deposition was performed to selectively adsorb A atoms onto the surface of Pt nanoparticles. Subsequently, annealing was performed to induce the migration or reconstruction of A atoms from the Pt surface, thus obtaining an A-Pt / C intermediate. Using a metal salt containing M atoms as a precursor solution, the A-Pt / C intermediate was immersed in the precursor solution by impregnation, followed by stirring and adsorption. Then, a reducing agent was added, and stirring continued to reduce the precursor to MO on the carbon support surface. x Nanoclusters, MO x Nanoclusters and Pt nanoparticles form Pt / MO x The interface provides the load MO. x Intermediates; Under a protective atmosphere or a protective atmosphere containing 5%–10% H2 by volume, the loaded MO x The intermediate was calcined to obtain a Pt-based synergistic catalyst.

7. The method for preparing the Pt-based synergistic catalyst according to claim 6, characterized in that, The vapor deposition temperature is 150℃~200℃, the time is 10min~30min, the annealing temperature is 200℃~300℃, the annealing time is 1h~2h, and the annealing atmosphere is an inert gas or an inert gas containing 5%~10% H2 by volume.

8. The method for preparing the Pt-based synergistic catalyst according to claim 6, characterized in that, The concentration of the precursor solution was 0.01 mol / L to 0.05 mol / L, the temperature for stirring and adsorption was 25℃ to 60℃, and the molar ratio of reducing agent to precursor was 2 to 5:

1.

9. The method for preparing the Pt-based synergistic catalyst according to claim 6, characterized in that, The calcination temperature is 300℃~400℃, the time is 2h~3h, and the heating rate is 5℃ / min~10℃ / min.

10. The application of the Pt-based synergistic catalyst according to any one of claims 1 to 5 as an anode catalyst in a proton exchange membrane fuel cell.

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