Preparation method and application of high-entropy nano-sponge CuNiFePdPt catalyst

Abstract

When the high-entropy nano-sponge CuNiFePdPt catalyst is synthesized, a Cu < 2 + >-containing salt precursor needs to be added, and preparation and co-reduction are carried out by utilizing the strong reducibility of sodium borohydride, so that the high-entropy alloy nano-sponge is prepared; cu, Ni, Fe, Pd and Pt elements in a zero-valence form exist on the high-entropy alloy nano sponge. The chemical general formula of the high-entropy nano-sponge CuNiFePdPt catalyst is CuxNiaFebPdcPtd, and x is more than or equal to 0.2 and less than or equal to 0.9, 0 lt; a is less than or equal to 0.3, 0lt; b is less than or equal to 0.3, 0lt; c is less than or equal to 0.8, 0lt; d < = 0.8, and x + a + b + c + d = 1. In the preparation of the catalyst, the reaction can be completed at room temperature by utilizing metal reduction potential difference and combining a specific charging sequence and whole-course stirring, complex conditions such as high temperature and high pressure are not needed, and the process is simple and controllable; the catalyst shows the comprehensive performance far better than that of a commercial catalyst in electro-catalysis ethylene glycol oxidation (EGOR).

Description

TECHNICAL FIELD

[0001] The application belongs to the field of fuel cell catalysts, and particularly relates to a preparation method and application of a high-entropy nano-sponge CuNiFePdPt catalyst. BACKGROUND

[0002] Under the background of global energy structure transformation, fuel cells have become an advantageous alternative to traditional fossil energy due to their efficient and clean energy conversion characteristics, and are one of the core technologies for future energy development. Among them, direct ethylene glycol fuel cells (DEGFC) have shown significant advantages due to the unique physicochemical properties of ethylene glycol: compared with traditional alcohols such as methanol and ethanol, ethylene glycol has a higher theoretical energy density, which can provide more stable energy support for portable electronic devices, new energy vehicles and other scenarios. At the same time, ethylene glycol can be converted into carbon dioxide and water by microorganisms in the ecological system, has low biological toxicity and environmental friendliness, and meets the increasing demand for ecological and environmental protection around the world. In addition, ethylene glycol, as a large-scale chemical product, has an annual output of over ten million tons, making it stand out from many direct fuel cells in terms of cost, and laying a cost advantage for the industrialization and popularization of DEGFC. In recent years, palladium-based nano-catalysts are considered to be one of the most promising EGOR materials, with excellent catalytic activity, stability and durability. However, due to the high cost, low quality activity, poor durability and stability, and easy poisoning of the current commercial palladium-carbon catalyst, the development and application of ethylene glycol fuel cells are limited. Therefore, the development of anode catalysts with low cost, high activity and durability is of great significance to the development of EGOR. SUMMARY

[0003] Based on the above background technology, the high-entropy alloy nano-sponge CuNiFePdPt is synthesized by a one-step reduction method at room temperature, using a cheap copper nanoweb as a template and taking advantage of the difference in metal reduction potential to solve the problems of high cost, low activity and poor stability of traditional ethylene glycol anode catalysts, and to reduce the dependence on noble metals. It is necessary to develop a preparation method and application of a high-entropy nano-sponge CuNiFePdPt catalyst.

[0004] The purpose of the present application is to provide a high-entropy nano-sponge CuNiFePdPt catalyst, which needs to add a Cu 2+ salt precursor during synthesis, and uses the strong reducing property of sodium borohydride for co-reduction to prepare a high-entropy alloy nano-sponge, so that Cu, Ni, Fe, Pd and Pt elements exist in the form of zero-valent on the high-entropy alloy nano-sponge.

[0005] As a preferred, the chemical formula of the high-entropy nano-sponge CuNiFePdPt catalyst is Cu x Nia Fe b Pd c Pt d , wherein 0.2≤x≤0.9, 0

[0006] A method for preparing a high-entropy alloy nanosponge CuNiFePdPt catalyst, comprising the following steps: Step 1, take sodium borohydride dissolved in deionized water to obtain a sodium borohydride solution; Step 2, the sodium borohydride solution of step 1 is added again to deionized water and stirred to obtain a dilute sodium borohydride solution; Step 3, a metal salt mixed solution is prepared, the metal mixed solution contains Cu 2+ , Ni 2+ , Pt 2+ , Pd 2+ , Fe 3+ , the metal concentration in the metal salt mixed solution is respectively: Cu 2+ (0.03-10 mmol / L), Ni 2+ (0.01-2 mmol / L), Pt 2 + (0.01-2 mmol / L), Pd 2+ (0.01-2 mmol / L), Fe 3+ (0.01-2 mmol / L); Step 4, the metal salt mixed solution of step 3 is added dropwise into the dilute sodium borohydride solution in step 2 and reacted under stirring; the precipitate after reaction is collected; Step 5, the precipitate of step 4 is washed by centrifugation with deionized water and then freeze-dried to obtain a high-entropy alloy nanosponge CuNiFePdPt catalyst.

[0007] Preferably, the mass concentration of the dilute sodium borohydride solution in step 2 is 0.2-0.9 mg / mL.

[0008] Preferably, the metal salt mixed solution in step 3 is prepared by taking 1 mL CuCl2·2H2O (0.1 mol L -1 ), 133 μL Ni(NO3)2 (0.1 mol L -1 ), 133 μL K2PtCl4 (0.1 mol L -1 ), 133 μL K2PdCl4 (0.1 mol L -1) and 133 μL FeCl3(0.1 mol L -1 ) into 20 ml aqueous solution.

[0009] As preferred, the volume ratio of the metal salt mixed solution in step 4 to the sodium borohydride dilute solution in step 2 is 1:5~1:10.

[0010] As preferred, the dropping speed in step 4 is 0.3~6 mL / min.

[0011] As preferred, the reaction time under stirring in step 4 is 0.5~1 h.

[0012] As preferred, the freezing temperature in step 5 is-198~-20 ℃, and the freezing time is 2~100 h.

[0013] A high-entropy nanosponge CuNiFePdPt catalyst can be used in the fields of electrocatalytic oxidation of ethylene glycol, oxygen reduction, electrochemical sensing, heterogeneous catalysis, etc.

[0014] The beneficial effects of the present application are: (1) Material design and cost control innovation A cheap copper nanoweb is used as a template, and non-noble metals such as Cu, Ni, and Fe are introduced to form a high-entropy alloy nanosponge structure with Pd and Pt noble metals, such as Figure 1 . As shown in the CuNiFePdPt high-entropy nanosponge XRD pattern, the characteristic diffraction peak at 2θ=42.06 ° corresponds to the (200) crystal plane, and is located between the standard cards of each metal element, verifying the formation of a single solid solution phase of CuNiFePdPt high-entropy alloy (the large wide peak at 2θ=23.31 ° is the diffraction peak of SiO2 measured due to the glass slide not being fully spread). This design greatly reduces the dependence on Pd and Pt noble metals, directly reduces the cost of the catalyst from the material composition level, and breaks through the cost bottleneck of traditional EGOR catalysts due to the high proportion of noble metals.

[0015] (2) Preparation method innovation A "room temperature one-step reduction method" is used to achieve efficient preparation: By utilizing the difference in metal reduction potential, combined with a specific feeding sequence (adding sodium borohydride reducing agent first, then dropping metal salt mixed solution) and stirring throughout the process, the reaction can be completed at room temperature without the need for complex conditions such as high temperature and high pressure; The process is simple and controllable (mixing, reaction, washing, and freeze-drying), easy to operate and scale up, and significantly simplifies the preparation process compared to the multi-step synthesis or high-temperature preparation process of traditional alloy catalysts.

[0016] (3) Catalytic performance and application innovation The high-entropy alloy nanosponge CuNiFePdPt catalyst prepared in the embodiment 1 of the present application has the following advantages: 1. The activity is greatly increased: the mass activity (5.54 A mg⁻¹) is 7.45 times that of the commercial Pd / C, and the catalytic efficiency is greatly improved; 2. The stability and durability are enhanced: the activity retention rate (87.18%) after 5000 s circulation is 1.58 times that of the commercial Pd / C, and the service life is prolonged; 3. The anti-poisoning and mass transfer advantages are superior to those of the commercial Pd / C: the anti-poisoning capacity (the ratio of the forward peak current to the reverse peak current is 6.36) and the mass transfer rate (the diffusion control slope is 0.271) are superior to those of the commercial Pd / C, and the problems of the traditional catalysts that are easily poisoned by intermediate products and the reaction rate is limited are solved.

[0017] In summary, the technology realizes the synergistic innovation in the three core dimensions of “low cost, easy preparation and high performance”, and provides an economical and practical solution for the EGOR catalysis field. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is an XRD diagram of the high-entropy alloy nanosponge CuNiFePdPt catalyst prepared in the embodiment 1 of the present application.

[0019] Figure 2 FIG. 2 is an SEM, TEM and EDS diagram and element distribution diagram of the high-entropy alloy nanosponge CuNiFePdPt catalyst prepared in the embodiment 1 of the present application.

[0020] Figure 3 FIG. 3 is the mass activity of the high-entropy alloy nanosponge CuNiFePdPt catalyst in step (3) in the embodiment 2 of the present application.

[0021] Figure 4 FIG. 4 is the stability i-t test curve diagram of the high-entropy alloy nanosponge CuNiFePdPt catalyst in step (2) in the embodiment 3 of the present application.

[0022] Figure 5 FIG. 5 is the mass activity curve of the high-entropy alloy nanosponge CuNiFePdPt catalyst in step (4) in the embodiment 2 of the present application under different scan speeds.

[0023] Figure 6 FIG. 6 is a linear fitting diagram of the peak mass activity and the square root of the scan speed of the high-entropy alloy nanosponge CuNiFePdPt catalyst in step (4) in the embodiment 2 of the present application under different scan speeds.

[0024] Figure 7This is a graph showing the percentage of initial mass activity retained by the high-entropy alloy nano-sponge CuNiFePdPt catalyst after the completion of the it test in step (3) of Example 3 of the present invention.

[0025] Figure 8 This refers to step (4) of Example 3 of the present invention, where the high-entropy alloy nano-sponge CuNiFePdPt catalyst is used at 50 mV s. -1 The ratio of the forward and reverse peak current densities of the cyclic voltammetry curve at the scan rate (I f / I b )picture. Detailed Implementation

[0026] This invention provides a method for preparing and applying a high-entropy nano-sponge CuNiFePdPt catalyst. The high-entropy alloy nano-sponge CuNiFePdPt catalyst uses Cu-containing... 2+ A co-reduction reaction was carried out between a salt precursor and sodium borohydride to prepare a high-entropy alloy nanosponge, which contains Cu, Ni, Fe, Pd and Pt elements in zero-valent form.

[0027] The high-entropy nanosponge CuNiFePdPt catalyst has the general chemical formula Cu. x Ni a Fe b Pd c Pt d Where 0.2≤x≤0.9, 0 <a≤0.3,0<b≤0.3,0<c≤0.8,0<d≤0.8,x+a+b+c+d=1。

[0028] This invention develops a high-entropy nano-sponge CuNiFePdPt catalyst and its preparation method. The high-entropy alloy nano-sponge CuNiFePdPt catalyst exhibits strong multi-metal synergistic effects and excellent continuous electronic structure regulation capabilities. Furthermore, the incorporation of oxyphilic metal elements Cu, Fe, and Ni can alter the d-band centers of noble metals such as palladium and platinum and induce lattice distortion, enabling the catalyst to better adsorb OH generated during the reaction. ads Reduce the toxic substance CO ad and -CH x The binding energy. On the other hand, the catalyst's unique porous sponge structure provides a large number of high-index crystal faces and abundant active sites, which helps improve the mass transfer efficiency of the catalytic reaction process, thereby enhancing catalytic performance and stability.

[0029] (1) Synthesis method steps High-entropy alloy nano-sponge CuNiFePdPt catalyst was prepared via a standard template reduction method. The preparation method of the high-entropy alloy nano-sponge CuNiFePdPt catalyst includes the following steps: Step 1, weigh 120 mg of sodium borohydride NaBH4 and dissolve in 30 mL of deionized water; Step 2, transfer the solution obtained in step 1 to a beaker containing 150 mL of water, and continuously stir with a mechanical stirrer; Step 3, use a pipette to take 1 mL of CuCl2·2H2O (0.1 mol L -1 ), 133 μL of Ni(NO3)2 (0.1 mol L -1 ), 133 μL of K2PtCl4 (0.1 mol L -1 ), 133 μL of K2PdCl4 (0.1 mol L -1 ) and 133 μL of FeCl3 (0.1 mol L -1 ) into 20 ml of aqueous solution.

[0030] Step 4, slowly add the metal salt mixed solution of step 3 to the beaker in step 2 within 5 minutes, continuously stir with a mechanical stirrer for 1 hour; Step 5, collect the product obtained in step 4, and centrifugally wash with deionized water for 3 times, and dry in a freeze dryer at -57℃ overnight (12 h) to obtain high-entropy alloy nanosponge CuNiFePdPt catalyst; The present application selects low-cost Cu nanosponge as a template, and prepares high-entropy alloy nanosponge CuNiFePdPt catalyst by a simple one-step reduction method. The prepared high-entropy alloy nanosponge CuNiFePdPt catalyst can be used for efficient and high-stable electrocatalytic oxidation of ethylene glycol, and serves as a potential new type of anode catalyst.

[0031] (2) Example Example

[0032] The preparation of high-entropy alloy nanosponge CuNiFePdPt catalyst includes the following steps: Weigh 120 mg of sodium borohydride NaBH4 and dissolve in 30 mL of deionized water, then transfer the obtained sodium borohydride solution to a beaker containing 150 mL of water, and continuously stir with a mechanical stirrer; use a pipette to take 1 mL of CuCl2·2H2O (0.1 mol L -1 ), 133 μL of Ni(NO3)2 (0.1 mol L -1 ), 133 μL of K2PtCl4 (0.1 mol L -1 ), 133 μL of K2PdCl4 (0.1 mol L -1) and 133 μL FeCl3(0.1 mol L -1 ) into 20 mL aqueous solution. The previously configured mixed solution of metal salts was slowly added dropwise into the previously containing sodium borohydride beaker within 5 minutes, and the reaction was continuously stirred by a mechanical stirrer for 1 hour; the reaction product was collected and washed with deionized water by centrifugation for 3 times, and dried in a freeze dryer at -57°C overnight to obtain high-entropy alloy nanosponge CuNiFePdPt catalyst, and the XRD pattern thereof is shown in Figure 1 . Figure 2 SEM, TEM and EDS images and element distribution map of the high-entropy alloy nanosponge CuNiFePdPt catalyst prepared in this example. Example

[0033] Application of high-entropy alloy nanosponge CuNiFePdPt catalyst in oxidation of ethylene glycol.

[0034] The performance of the high-entropy alloy nanosponge CuNiFePdPt catalyst in Example 1 was determined in a three-electrode system, and the catalytic activity curve of electrocatalytic oxidation of ethylene glycol in 0.5 mol L -1 KOH and 0.5 mol L -1 EG mixed solution was drawn: The product obtained in Example 1 was weighed at 5 mg, ultrasonically dispersed in a mixed solution of 960 μL ultrapure water, 1000 μL ethanol and 40 μL 10% Nafion solution to prepare catalyst ink, 1 μL of the obtained ink was dropped on a glassy carbon electrode and naturally dried at room temperature, and the test was performed in a three-electrode system using an electrochemical workstation.

[0035] The glassy carbon electrode after drying in Example 2 step (1) was used as the working electrode, a carbon rod was used as the counter electrode, Hg / HgO was used as the reference electrode, and 0.5 mol L -1 KOH and 0.5 mol L -1 EG mixed solution was used as the electrolyte. The current density of the high-entropy alloy nanosponge CuNiFePdPt catalyst was collected at a scan rate of 50 mV s -1 , and the mass activity of the high-entropy alloy nanosponge CuNiFePdPt catalyst was calculated as shown in Figure 3 , and it can be seen that the mass activity of the catalyst reached 5.54 A mg⁻¹, which was 7.45 times that of commercial Pd / C, and the catalytic performance was significantly improved. The calculation formula of the mass activity of the catalyst is: , C max is the peak current (A) of the measured cyclic voltammetry curve, and M iA represents the mass (mg) of the catalyst dropped onto the glassy carbon electrode. i The mass activity of the catalyst (A mg) -1 ).

[0036] At 5 mV s -1 10 mV s -1 20 mV s -1 50 mV s -1 75 mV s -1 and 100 mV s -1 The scan rate was used to collect the mass activity change curves of the high-entropy alloy nanosponge CuNiFePdPt catalyst, as shown in the figure. Figure 5 As shown; and a linear fit was performed between peak mass activity and the square root of the scan rate; as shown Figure 6 The results show that the catalytic oxidation rate conforms to first-order catalytic kinetics, and the slope of the fitted line is greater than that of the fitted line for commercial Pd / C, indicating that it has a faster catalytic alcohol oxidation rate. Example

[0037] The performance of the high-entropy alloy nanosponge CuNiFePdPt catalyst from Example 1 was determined in a three-electrode system, and plots were generated for 0.5 mol L⁻¹. -1 KOH and 0.5 mol L -1 Stability, antitoxicity, and durability of EG mixed solution in electrocatalytic ethylene glycol oxidation: The test was conducted using an electrochemical workstation with a three-electrode system. The glassy carbon electrode dried in step (1) of Example 2 was used as the working electrode, a carbon rod as the counter electrode, and Hg / HgO as the reference electrode. 0.5 mol L -1 KOH and 0.5 mol L -1 The EG mixed solution is an electrolyte; With 50 mV s -1 The stability of the catalyst was tested at a scan rate of 5000 s, and the decay curve of the current density during the test was recorded. Figure 4 As shown; and the decay curve of its mass activity is calculated by the formula in step (3) of Example 2.

[0038] The residual mass activity of the high-entropy alloy nanosponge CuNiFePdPt catalyst after the completion of the IT test was collected, such as... Figure 7 As shown, the residual mass activity of the high-entropy alloy nanosponge CuNiFePdPt is much higher than that of commercial Pd / C, and it has good stability and durability.

[0039] Collect 50mV s -1 The ratio of the forward and reverse peak current densities of the cyclic voltammetry curve at the scan rate (If / I b ), as shown in I Figure 8 I of high-entropy alloy nanosponge CuNiFePdPt shown in f / I b The ratio is 6.3, higher than the commercial Pd / C, indicating that the prepared high-entropy alloy nanosponge CuNiFePdPt has good anti-poisoning.

[0040] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-entropy nanosponge CuNiFePdPt catalyst, characterized in that, Cu is required to be added during synthesis 2+ The salt precursor is prepared by co-reduction using the strong reducing property of sodium borohydride, thereby preparing a high-entropy alloy nanosponge; Cu, Ni, Fe, Pd and Pt elements in zero-valence form exist on the high-entropy alloy nanosponge. 2.The high-entropy nanosponge CuNiFePdPt catalyst of claim 1, wherein, The high-entropy nanosponge CuNiFePdPt catalyst has a chemical formula of Cu x Ni a Fe b Pd c Pt d , wherein 0.2≤x≤0.9, 0 3. A method for preparing the high-entropy alloy nanosponge CuNiFePdPt catalyst according to any one of claims 1-2, characterized in that, The method comprises the following steps: Step 1, sodium borohydride is dissolved in deionized water to obtain a sodium borohydride solution; Step 2, the sodium borohydride solution in step 1 is added into deionized water again and stirred to obtain a diluted sodium borohydride solution; Step 3, configuring a metal salt mixed solution, the metal mixed solution contains Cu 2+ , Ni 2+ , Pt 2+ , Pd 2+ , Fe 3+ , the metal concentration in the metal salt mixed solution is respectively: Cu 2+ (0.03-10 mmol / L), Ni 2+ (0.01-2 mmol / L), Pt 2+ (0.01-2 mmol / L), Pd 2+ (0.01-2 mmol / L), Fe 3+ (0.01-2 mmol / L); Step 4, the mixed metal salt solution in step 3 is added dropwise into the diluted sodium borohydride solution in step 2 and reacted under stirring; the precipitate after reaction is collected; Step 5, the precipitate in step 4 is centrifugally washed with deionized water and then freeze-dried to obtain a high-entropy alloy nanosponge CuNiFePdPt catalyst.

4. The method of claim 3, wherein, The mass concentration of the diluted sodium borohydride solution in step 2 is 0.2-0.9 mg / mL.

5. The method of claim 3, wherein, The metal salt mixed solution in Step 3 was prepared by adding 1 mL of CuCl2-2H2O (0.1 mol L -1 ), 133 μL of Ni(NO3)2(0.1 mol L -1 ), 133 μL of K2PtCl4(0.1 mol L -1 ), 133 μL of K2PdCl4(0.1 mol L -1 ), and 133 μL of FeCl3(0.1 mol L -1 ) to 20 mL of water.

6. The method of claim 3, wherein, The volume ratio of the mixed metal salt solution in step 4 to the diluted sodium borohydride solution in step 2 is 1:5-1:

10.

7. The method of claim 3, wherein, The dropping speed in step 4 is 0.3-6 mL / min.

8. The method of claim 3, wherein, The reaction time under stirring in step 4 is 0.5-1 h.

9. The method of claim 3, wherein, The freeze-drying temperature in step 5 is-198--20℃, and the freezing time is 2-100 h.

10. The application of the high-entropy nanosponge CuNiFePdPt catalyst according to any one of claims 1-2, wherein the catalyst can be used in the fields of electrocatalytic oxidation of ethylene glycol, oxygen reduction, electrochemical sensing and heterogeneous catalysis.

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