Palladium-based catalyst PdRhCu as well as preparation method and application thereof

Abstract

The invention discloses a palladium-based catalyst PdRhCu and a preparation method and application thereof, and belongs to the technical field of proton exchange membrane fuel cells, and the preparation method of the PdRhCu catalyst comprises the following steps: filling Pd (acac) 2, RhCl3, Cu (acac) 2 and KOH into a small bottle, adding DMF and EG, carrying out ultrasonic dissolution, and uniformly mixing; dETA is added into the solution, the obtained solution is transferred into a 25 mL reaction kettle, and a product is obtained at high temperature and high pressure and centrifugally washed and collected; through the synergistic effect of Pd, Rh and Cu, the d band center of Pd is reduced, the morphology is adjusted by adding DMF, EG and DETA, and more active sites are exposed; when the catalyst is used as a proton exchange membrane fuel cell positive electrode catalyst, the power density and the stability are higher than those of commercial 20% Pt / C; the method is simple and feasible in process, low in cost, simple to operate and capable of realizing large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of proton exchange membrane fuel cells, and specifically relates to a palladium-based catalyst PdRhCu and a preparation method and application thereof. Background Art

[0002] Proton exchange membrane fuel cells (PEMFCs) represent a clean and sustainable energy conversion vehicle for transportation and stationary power generation. However, the high cost and poor performance of platinum group metal catalysts such as Pt and Pd for the oxygen reduction reaction (ORR) at the cathode of fuel cells have hindered the large-scale commercialization of PEMFCs. Alloying of precious metals with non-precious metals improves ORR activity while reducing the cost of catalysts. However, the high atomic percentage of platinum-based metals used in state-of-the-art alloy catalysts and their poor activity and durability under fuel cell operating conditions constitute the main obstacle to the large-scale commercialization of fuel cells. Even if alternative catalysts to Pt are developed, such as Pd-based oxygen reduction catalysts, to reduce the dependence on Pt, the activity of Pd in ​​catalyzing ORR can be improved through strategies such as alloying, but the stability of Pd under acidic conditions is poor. How to improve ORR activity in acidic environments remains challenging. Therefore, the purpose of this work is to improve the efficiency of Pd-based oxygen reduction catalysts for use in the field of proton exchange membrane fuel cells.

[0003] In recent years, two-dimensional metal materials with atomic layer thickness are very promising electrocatalytic materials. This is mainly because compared with other catalysts and two-dimensional materials, metalloene is a graphene-like two-dimensional nanomaterial molecule with a thickness of less than 5 nanometers. Its flexible microstructural adjustability, highly exposed metal active sites and simple and clear structural patterns make metalloene an ideal carrier for fixing single atoms, clusters or nanoparticles. At the same time, studies have shown that the strong metal interaction between Cu and Rh can form activated Rh-coordinated Cu single-atom active sites, which is conducive to optimizing the adsorption and activation between active sites and reactants in electrocatalytic reactions. Summary of the invention

[0004] Technical issues solved:

[0005] The present application aims to address the shortcomings of the prior art, such as the poor stability of Pd under acidic conditions, the high cost and poor performance of catalysts such as Pt and Pd, and the slow kinetic reaction of the cathode oxygen reduction reaction as the most important half-reaction in the fuel cell, which seriously affects the performance of the fuel cell. A palladium-based catalyst PdRhCu and a preparation method and application thereof are provided. The method of the present invention is simple and universal, low in cost, and the prepared PdRhCu alloy material exhibits excellent activity and stability as an oxygen reduction electrocatalyst, and exhibits good power density as a positive electrode material for a proton exchange membrane fuel cell.

[0006] Technical solution:

[0007] To achieve the above objectives, this application is implemented through the following technical solutions:

[0008] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0009] Step 1: Take Pd(acac) according to mass volume ratio 2 5-10mg, RhCl 3 5-10 mg, Cu(acac) 2 5-10 mg and KOH 1.2-2.4 g are placed in a 30 mL vial;

[0010] Step 2: Add 6-12 mL DMF and 4-8 mL EG into the vial and dissolve by ultrasonic to obtain a uniformly mixed solution;

[0011] Step 3: Add 5-10 mL of DETA to the mixed solution to obtain a mixed solution;

[0012] Step 4: Transfer the mixed solution to a 25 mL reactor and heat it;

[0013] Step 5: The product obtained after heating in the reactor is centrifugally washed and collected with ethanol and acetone to obtain a palladium-based catalyst PdRhCu.

[0014] Furthermore, the ultrasonic time in the second step of ultrasonic dissolution is 40 minutes.

[0015] Furthermore, the heating condition in the fourth step reaction kettle is heating at 100-200° C. for 8-10 h.

[0016] Furthermore, in the fifth step, the centrifugal speed is 10000 r / min and the centrifugal time is 8 min.

[0017] A palladium-based catalyst PdRhCu prepared by any of the above preparation methods.

[0018] Furthermore, in the palladium-based catalyst PdRhCu, Pd, Rh and Cu exist in the form of single atoms.

[0019] Furthermore, the morphology of the palladium-based catalyst PdRhCu is a defect-rich ultra-thin two-dimensional nanosheet.

[0020] The present application also discloses the application of the palladium-based catalyst PdRhCu in the positive electrode material of the proton exchange membrane fuel cell.

[0021] The present application also discloses the use of a palladium-based catalyst PdRhCu in an acidic oxygen reduction reaction catalyst.

[0022] Principle explanation: Palladium acetylacetonate, rhodium chloride and copper acetylacetonate are used as metal sources, EG is used as solvent, and DETA is used as a structure-directing agent to guide the growth of two-dimensional nanosheet structures; KOH can induce the decomposition of DMF to generate dimethylamine, promote the growth of the two-dimensional structure, and provide OH* during the synthesis process to promote the surface hydroxylation of PdRhCu metal olefins; the material has a neat morphology and presents a two-dimensional nanosheet shape; the PdRhCu nanosheets have a small size, reaching the atomic level, with rich surface defects and many active sites. The obtained material has high oxygen reduction activity and excellent stability under acidic conditions.

[0023] Beneficial effects:

[0024] The present application provides a palladium-based catalyst PdRhCu and a preparation method and application thereof, which have the following beneficial effects compared with the prior art:

[0025] 1. The synergistic effect of the metal Cu and Pd etc. of the present invention will improve the durability of the catalyst;

[0026] 2. The metal Cu of the present invention can reduce the d-band center of Pd, thereby preventing the active sites on Pd from being covered by CO;

[0027] 3. The synergistic effect of the oxygen-philic metal Rh and Pd etc. of the present invention can improve the CO anti-poisoning ability;

[0028] 4. Palladium-based catalysts have high density, corrosion resistance and high electrothermal stability;

[0029] 5. Palladium-based catalysts have a huge affinity for H and O;

[0030] 6. Palladium, as a member of the same family as platinum, has similar intrinsic properties to platinum and is more abundant in reserves than platinum.

[0031] 7. Metalloene has a unique two-dimensional structure with high specific surface area, abundant defect sites, excellent conductivity, and exposes a large number of unsaturated catalytic active sites;

[0032] 8. The preparation method of palladium-based catalyst PdRhCu is a one-pot wet chemical method, which is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a SEM spectrum of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for use as a positive electrode material for a proton exchange membrane fuel cell;

[0034] Figure 2 This is the TEM spectrum of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for use as a positive electrode material for a proton exchange membrane fuel cell;

[0035] Figure 3 This is the HR-TEM spectrum of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for the positive electrode material of a proton exchange membrane fuel cell;

[0036] Figure 4 This is the XRD spectrum of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for the positive electrode material of a proton exchange membrane fuel cell;

[0037] Figure 5 The LSV curve of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for the positive electrode material of a proton exchange membrane fuel cell;

[0038] Figure 6 The Tafel curve of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for the positive electrode material of a proton exchange membrane fuel cell;

[0039] Figure 7 Polarization and corresponding power density curve of the palladium-based catalyst PdRhCu prepared in Example 1 of the present application for the positive electrode material of a proton exchange membrane fuel cell;

[0040] Figure 8 The LSV curves of the materials obtained in Example 1 of the present application and Comparative Examples 1 to 2 are compared. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] Example 1

[0043] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0044] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0045] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0046] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0047] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0048] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0049] The PdRhCu catalyst material prepared in Example 1 was physically characterized by SEM, TEM, HR-TEM and XRD. Figure 1 From the SEM image, it can be seen that the material is composed of metal nanosheet structures. Figure 2 The TEM image shows ultrathin two-dimensional nanosheets, which is consistent with the SEM results. Figure 4 It can be seen from the XRD spectrum that the diffraction peaks of the material are completely consistent with the standard card of Pd (JCPDS card, 05-0681), proving the successful preparation of the catalyst PdRhCu. Figure 5 This is the LSV graph obtained by testing the oxygen reduction performance of the material. It can be seen from the figure that the initial reduction potential and half-wave potential are 1.04 and 0.93V respectively. Figure 6 The Tafel curve shown shows that the value of the Tafel slope of this material is only 23.87mV dec -1 , which is superior to most acidic oxygen reduction electrocatalyst materials. Figure 7 The polarization curve and corresponding power density curve of the material as the positive electrode material of proton exchange membrane fuel cell show that the material has a high power density, and its maximum power density is 801mW cm -2 The above results all indicate that this material has a good application prospect as an alkaline oxygen reduction electrocatalyst material.

[0050] Example 2

[0051] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0052] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 10 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0053] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0054] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0055] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0056] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0057] Example 3

[0058] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0059] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 10 mg and KOH 1.2 g were placed in a 30 mL vial;

[0060] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0061] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0062] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0063] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0064] Example 4

[0065] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0066] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 2.4 g were placed in a 30 mL vial;

[0067] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0068] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0069] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0070] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0071] Example 5

[0072] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0073] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0074] Step 2: Add 12 mL of DMF and 4 mL of EG into the vial and dissolve them by ultrasonic for 40 min to obtain a well-mixed solution;

[0075] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0076] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0077] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0078] Example 6

[0079] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0080] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0081] Step 2: Add 6 mL of DMF and 8 mL of EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0082] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0083] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0084] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0085] Example 7

[0086] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0087] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0088] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0089] Step 3: Add 10 mL of DETA to the mixed solution to obtain a mixed solution;

[0090] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0091] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0092] Example 8

[0093] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0094] Step 1: Take Pd(acac) according to mass volume ratio 2 5mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0095] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0096] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0097] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 10 h;

[0098] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0099] Example 9

[0100] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0101] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0102] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0103] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0104] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 200 °C for 8 h;

[0105] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0106] Example 10

[0107] A method for preparing a palladium-based catalyst PdRhCu, comprising the following steps:

[0108] Step 1: Take Pd(acac) according to mass volume ratio 2 10mg, RhCl 3 5 mg, Cu(acac) 2 5 mg and KOH 1.2 g were placed in a 30 mL vial;

[0109] Step 2: Add 6 mL DMF and 4 mL EG into the vial and dissolve by ultrasonic for 40 min to obtain a well-mixed solution;

[0110] Step 3: Add 5 mL of DETA to the mixed solution to obtain a mixed solution;

[0111] Step 4: Transfer the mixed solution to a 25 mL reactor and heat at 100 °C for 10 h;

[0112] Step 5: The product obtained after heating in the reactor is washed and collected by centrifugation with ethanol and acetone at a centrifugal speed of 10000 r / min and a centrifugal time of 8 min to obtain a palladium-based catalyst PdRhCu.

[0113] Comparative Example 1

[0114] The difference between this comparative example and Example 1 is that RhCl is not added. 3 , the other implementation conditions remain unchanged.

[0115] Comparative Example 2

[0116] The difference between this comparative example and Example 1 is that no Cu(acac) is added. 2 , the other implementation conditions remain unchanged.

[0117] The LSV test results of the corresponding oxygen reduction reaction are as follows: Figure 8 As shown, the overall performance comparison shows the order of PdRhCu>20%Pt / C>PdRh>PdCu, and the performance of Comparative Example 1 is better than that of Comparative Example 2.

[0118] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a palladium-based catalyst PdRhCu, characterized in that: The specific steps are: Step 1: Pd(acac) 25-10 mg, RhCl3 5-10 mg, Cu(acac) 25-10 mg and KOH 1.2-2.4 g were placed in a 30 mL vial according to the mass volume ratio; Step 2: Add 6-12 mL DMF and 4-8 mL EG into the vial and dissolve by ultrasonic to obtain a uniformly mixed solution; Step 3: Add 5-10 mL of DETA to the mixed solution to obtain a mixed solution; Step 4: Transfer the mixed solution to a 25 mL reactor and heat it; Step 5: The product obtained after heating in the reactor is centrifugally washed and collected with ethanol and acetone to obtain a palladium-based catalyst PdRhCu.

2. A method for preparing a palladium-based catalyst PdRhCu according to claim 1, characterized in that: The ultrasonic time in the second step of ultrasonic dissolution is 40 minutes.

3. A method for preparing a palladium-based catalyst PdRhCu according to claim 1, characterized in that: The heating condition in the fourth step reaction kettle is heating at 100-200° C. for 8-10 hours.

4. A method for preparing a palladium-based catalyst PdRhCu according to claim 1, characterized in that: In the fifth step, the centrifugal speed is 10000 r / min and the centrifugal time is 8 min.

5. A palladium-based catalyst PdRhCu prepared by the preparation method according to any one of claims 1 to 4.

6. The palladium-based catalyst PdRhCu according to claim 5, characterized in that: The palladium-based catalyst In PdRhCu, Pd, Rh and Cu exist in the form of single atoms.

7. The palladium-based catalyst PdRhCu according to claim 5, characterized in that: The palladium-based catalyst The morphology of PdRhCu is ultra-thin two-dimensional nanosheets rich in defects.

8. Use of the palladium-based catalyst PdRhCu according to claim 5 in a positive electrode material for a proton exchange membrane fuel cell.

9. Use of the palladium-based catalyst PdRhCu according to claim 5 in an acidic oxygen reduction reaction catalyst.

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