A flexible carbon cloth-supported porous Pd metal electrode, its preparation method and application
By preparing porous Pd metal electrodes on flexible carbon cloth substrates using impregnation reduction and dealloying processes, the problems of high cost and low utilization of noble metal Pd in H2O2 electroreduction catalysts were solved, achieving high efficiency, low cost, and good catalytic performance and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGBEI UNIV
- Filing Date
- 2022-12-30
- Publication Date
- 2026-07-17
AI Technical Summary
In existing technologies, the use of precious metal Pd as an electroreduction catalyst for H2O2 suffers from high cost and low utilization rate. In particular, under acidic systems, it is difficult to balance the stability and high utilization rate of Pd.
Porous Pd metal electrodes were prepared on flexible carbon cloth substrates using an impregnation reduction method and a "dealloying" process, avoiding the use of binders and improving the specific surface area of the catalyst and the utilization rate of precious metals through the "dealloying" process.
This improves the catalytic performance and utilization rate of Pd metal electrodes, reduces electrode costs, and ensures electrode stability and flexibility, facilitating industrial production.
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Figure CN116154186B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalytic reduction technology, specifically relating to a flexible carbon cloth-supported porous Pd metal electrode, its preparation method and application, which is used in the catalytic electroreduction of hydrogen peroxide. Background Technology
[0002] Fuel cells, as a novel energy device that can directly convert the chemical energy in fuel and oxidant into electrical energy, have attracted increasing attention. H2O2, as an oxidant that can replace oxygen, is liquid under normal temperature and pressure conditions, offering advantages such as ease of storage, transportation, and high safety. Furthermore, it provides the conditions for fuel cells to operate in oxygen-free environments; fuel cells using hydrogen peroxide as an oxidant are considered strong contenders for next-generation aerospace and underwater energy devices.
[0003] As the primary site for reduction reactions, the activity of electrode catalysts plays a crucial role in improving battery performance. In acidic systems, the reduction potential of H₂O₂ is higher, and transition metals are not stable in acidic environments; therefore, noble metals have become the primary choice for cathode catalysts. Pd is more abundant than Pt, and more importantly, it exhibits better catalytic activity towards H₂O₂ (Fan Y, Cheng K, Mo Y, et al. Direct peroxide–peroxide fuelcell – Part 1: The anode and cathode catalyst of carbon fiber cloth supported dendritic Pd[J]. Journal of Power Sources, 2012, 217(NOV.1):562-568.). However, its high price and limited reserves also increase the cost of fuel cells. Therefore, increasing the specific surface area of the electrode to minimize the Pd metal loading while ensuring performance is an important method to reduce electrode costs. Summary of the Invention
[0004] This invention aims to improve Pd metal utilization and electrode catalytic performance, and to reduce catalyst costs. It provides a flexible carbon cloth-supported porous Pd metal electrode, its preparation method, and its application. This electrode is used in the catalytic electroreduction of hydrogen peroxide. Porous Pd metal is prepared using an impregnation reduction method and a dealloying process, serving as a raw material for the electroreduction of H2O2. This improves Pd metal utilization and electrode catalytic performance, providing a method and approach for reducing catalyst costs.
[0005] The present invention is achieved by the following technical solution: a porous Pd metal electrode supported by flexible carbon cloth, wherein the porous Pd metal electrode is prepared on a flexible carbon cloth substrate by impregnation reduction method and "dealloying" process.
[0006] The method for preparing the flexible carbon cloth-supported porous Pd metal electrode comprises the following steps:
[0007] (1) Arrange carbon in a hydrothermal reactor, add nitric acid and keep warm at 120°C for 240 min. After cooling to room temperature, wash thoroughly with deionized water and then dry in a 70°C forced-air drying oven for 3 h.
[0008] (2) The pretreated carbon was immersed in a mixed solution of PdCl2 and FeCl3 for 5 min, and then dried in a 160℃ forced-air drying oven for 15 min. The dried carbon was then placed in a 0.1 mol·dm³ solution. -3 PdFe composite material was prepared on the surface of carbon cloth by chemical reduction in NaBH4 solution for 5 min. After thorough washing with deionized water, it was placed in a 6 mol·dm³ solution. -3 Fe metal in PdFe composite material is removed by HCl solution; the above operation is a cycle, repeated 2-10 times to obtain a porous Pd metal electrode supported by flexible carbon cloth.
[0009] The nitric acid concentration mentioned in step (1) is 65-68%, and the nitric acid in the hydrothermal reactor should be at least 1 cm above the carbon cloth to ensure complete oxidation of the carbon cloth.
[0010] In step (2), the concentration of PdCl2 in the mixed solution of PdCl2 and FeCl3 is 5 mmol·dm³. -3 The FeCl3 concentration was 0.5 mmol·dm³. -3 -2.0 mmol·dm -3 Repeat 6 times to obtain a porous Pd metal electrode supported by flexible carbon cloth.
[0011] In step (2), the FeCl3 concentration is 1.0 mmol·dm³. -3 .
[0012] The present invention also provides the application of the aforementioned flexible carbon cloth-supported porous Pd metal electrode in the catalytic electroreduction of H2O2.
[0013] The specific application process is as follows: a porous Pd metal electrode supported by flexible carbon cloth is used as the working electrode, and a silver chloride electrode and a graphite rod are used as the reference electrode and counter electrode, respectively, at a temperature of 0.5-2.5 mol·dm³. -3 H2SO4 and 0.5-2.5 mol·dm -3 Catalytic electroreduction of H2O2 in H2O2 solution.
[0014] Impregnation reduction is an effective method for preparing electrode materials, avoiding the use of binders and the resulting reduction in conductivity. Compared to electrodeposition, impregnation reduction allows for arbitrary changes in electrode shape and area under the same preparation conditions, ensuring the electrode can be used in batteries of any structure. The dealloying process can be used to prepare porous electrodes, thereby increasing the specific surface area of the electrode catalyst, improving the utilization rate of noble metal catalysts, and reducing electrode costs.
[0015] This invention utilizes an impregnation-reduction method to prepare PdFe composite materials. This method eliminates the need for binders during preparation, resulting in excellent electrode conductivity, high catalyst utilization, and avoids the catalyst dead zone problem caused by catalyst coating. Furthermore, the impregnation-reduction method prevents material detachment during testing, ensuring a stable electrode structure. Third, the "dealloying" process removes metallic Fe from the PdFe composite material, giving the Pd electrode a porous structure and a high specific surface area, thus improving the utilization rate of the precious metal Pd and enhancing electrode performance. This also helps reduce catalyst usage and electrode costs. Fourth, the electrode preparation process is simple and not limited by electrode shape or area, facilitating industrial production and use. Attached Figure Description
[0016] Figure 1 This is a comparison graph showing the catalytic performance of electrodes prepared using mixed impregnation solutions with different Fe contents for H2O2 in Example 1.
[0017] Figure 2 Chronoamperometry results of the flexible carbon cloth-loaded porous Pd electrode prepared in Example 2 at different voltages;
[0018] Figure 3 Figure (a) shows the CV test results of the porous Pd electrode (a) and Pd electrode (b) supported on flexible carbon cloth in H2SO4 solution at different scan rates in Example 3. Figure (c) shows the linear fitting of the current of the porous Pd electrode and Pd electrode supported on carbon cloth with scan rate at a voltage of 0.20 V.
[0019] Figure 4 Transmission electron microscopy (TEM) images of the porous Pd electrode supported on flexible carbon cloth in Example 4 at different magnifications.
[0020] Figure 5 The images show the XRD characterization of the flexible carbon cloth-supported porous Pd electrode under different preparation steps in Example 4.
[0021] Figure 6 The images shown are scanning electron microscope (SEM) and electronic spectroscopy (EDS) images of the flexible carbon cloth-loaded porous Pd electrode at different magnifications in Example 4.
[0022] Figure 7This is a comparison chart of the electroreduction performance of H2O2 catalyzed by different electrodes in Example 5;
[0023] Figure 8 This is a comparison chart of the performance of single cells with different electrode compositions in Example 5. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and all materials publicly cited herein and cited by them are incorporated herein by reference.
[0026] Equivalent technologies of the specific embodiments described herein that are readily apparent to those skilled in the art through routine experimentation are included in this application.
[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the instruments and equipment used in the following examples are all standard laboratory instruments and equipment; unless otherwise specified, the experimental materials used in the following examples were all purchased from regular biochemical reagent stores.
[0028] Example 1: A porous Pd metal electrode supported by flexible carbon cloth was prepared on a flexible carbon cloth substrate using an impregnation reduction method and a dealloying process. The specific method is as follows:
[0029] (1) The carbon cloth is placed in a hydrothermal reactor, nitric acid is added and kept at 120°C for 240 min. After cooling to room temperature, it is cleaned and dried to improve the hydrophilicity of the carbon cloth.
[0030] (2) The pretreated carbon was arranged in a 5 mmol·dm³ container. -3 PdCl2 and 2.0 mmol·dm -3 The carbon was immersed in a mixed FeCl3 solution for 5 min, then dried in a 160℃ forced-air drying oven for 15 min. The dried carbon was then arranged in a 0.1 mol·dm³ solution. - 3 PdFe composite material was prepared by chemical reduction in NaBH4 solution for 5 min on the surface of carbon cloth. After thorough washing with deionized water, it was placed in a 6 mol·dm³ solution. -3The Fe metal in the PdFe composite material is removed using an HCl solution. This process constitutes one cycle; repeating this cycle six times yields a porous Pd metal electrode supported by flexible carbon cloth.
[0031] The resulting flexible carbon cloth-supported porous Pd metal electrode is applied by using the electrode prepared by the above method as the working electrode, and a silver chloride electrode and a graphite rod as the reference electrode and counter electrode, respectively, placed in a 1.5 mol·dm³ atmosphere. -3 H2SO4 and 1.5 mol·dm -3 Cyclic voltammetry was performed in an H₂O₂ solution. Process parameters: scan range 0.6 to -0.2 V, scan rate 10 mV / s. -1 The result is as follows Figure 1 As shown, the results indicate that when the FeCl3 concentration in the impregnation solution is 1.0 mmol·dm³, the concentration of FeCl3 is... -3 The performance reaches 889 mA·cm -2 Compared to electrodes prepared without FeCl3 in the impregnation solution, the performance of the electrodes is significantly improved. This is mainly due to the fact that the "dealloying" method imparts more defects to the electrode surface, which is beneficial for exposing the active sites on the catalyst surface, thereby improving the catalytic performance of the electrode.
[0032] Example 2: A porous Pd metal electrode supported by flexible carbon cloth was prepared on a flexible carbon cloth substrate using an impregnation reduction method and a dealloying process. Specifically, pretreated carbon was arranged on a 5 mmol·dm³ substrate. -3 PdCl2 and 1.0 mmol·dm -3 The electrode is immersed in a FeCl3 mixed solution for 5 minutes, then dried in a 160°C forced-air drying oven for 15 minutes. The remaining steps are the same as those described in Example 1, and a porous Pd metal electrode supported by flexible carbon cloth can be obtained.
[0033] The inductively coupled plasma atomic emission spectrometry (ICP-OES) results of the obtained flexible carbon cloth-supported porous Pd metal electrode are shown in Table 1. The results show that the Pd element content of this material is 5.94~5.95% after two repeated tests.
[0034] Table 1: Inductively Coupled Plasma Emission Spectroscopy (ICP-OES) Results of the Flexible Carbon Cloth Supported Porous Pd Metal Electrode Prepared in Example 2
[0035]
[0036] The resulting flexible carbon cloth-supported porous Pd metal electrode was used as the working electrode, with a silver chloride electrode and a graphite rod serving as the reference and counter electrodes, respectively. The electrode was placed in a 2.0 mol·dm³ atmosphere. -3H2SO4 and 1.5 mol·dm -3 Chronoamperometry was performed in H₂O₂ solution. Process parameters: scan potential -0.1-0.3V, scan rate 10 mVs. -1 The scan time was 1800 seconds. The results are as follows: Figure 2 As shown in the results, the electrode remained stable during multiple chronocurrent scans, and no electrode detachment occurred, indicating that the electrode prepared by this method has good stability.
[0037] Example 3: A porous Pd metal electrode supported by flexible carbon cloth was prepared on a flexible carbon cloth substrate using an impregnation reduction method and a dealloying process. Specifically, pretreated carbon was arranged on a 5 mmol·dm³ substrate. -3 PdCl2 and 1.0 mmol·dm -3 The carbon was immersed in a mixed solution of FeCl3 for 5 min, and the dried carbon was arranged in a 0.1 mol·dm³ solution. - 3 Chemical reduction in NaBH4 solution for 5 min, with the remaining methods being the same as those shown in Example 1.
[0038] In contrast, in a solution containing only 5 mmol·dm -3 A carbon cloth-supported Pd metal electrode without porous structure is prepared by impregnation in a PdCl2 solution while keeping other preparation steps unchanged.
[0039] The resulting flexible carbon cloth-supported porous Pd metal electrode and ordinary Pd metal electrode were applied. The electrode prepared by the above method was used as the working electrode, and a silver chloride electrode and a graphite rod were used as the reference electrode and counter electrode, respectively. The electrodes were placed in a 2 mol·dm³ atmosphere. -3 Cyclic voltammetry was performed in an H₂SO₄ solution. Process parameters: scan range 0.25–0.15 V, scan rate 5–20 mV / s. -1 .
[0040] The results are as follows Figure 3 As shown in (a~b), combined with Figure 3 (c) The effective area of the porous Pd electrode supported by flexible carbon cloth, calculated using the slope of the fitted curve and formulas (1-2), is 25.5 cm². 2 The effective area of the Pd electrode without a porous structure is 21.8 cm². 2 It can be seen that imparting a porous structure to the Pd catalyst through the "dealloying" method can effectively increase the effective area of the catalyst. In the formula, C d denoted as ε0, where A is the effective area of the electrode and C* is the theoretical double-layer capacitance.
[0041] Example 4: A porous Pd metal electrode supported by flexible carbon cloth was prepared on a flexible carbon cloth substrate using an impregnation reduction method and a dealloying process. Specifically, pretreated carbon was arranged on a 5 mmol·dm³ substrate. -3 PdCl2 and 1.0 mmol·dm -3 The carbon was immersed in a mixed solution of FeCl3 for 5 min, and the dried carbon was arranged in a 0.1 mol·dm³ solution. - 3 Chemical reduction in NaBH4 solution for 5 min, with the remaining methods being the same as those shown in Example 1.
[0042] The obtained porous Pd metal electrode supported by flexible carbon cloth was characterized by transmission electron microscopy, and the results are as follows: Figure 4 As shown, Pd metal is attached to the carbon cloth surface in a spherical shape, and the surface of the Pd metal spheres is made "wrinkled" by the "dealloying" method. These "wrinkles" increase the effective area of the electrode, making the electrode have higher catalytic performance for the electroreduction of H2O2.
[0043] The obtained porous Pd metal electrode supported by flexible carbon cloth was characterized by XRD, and the results are as follows: Figure 5 As shown, in addition to the obvious characteristic peaks corresponding to graphite carbon, there are also characteristic peaks corresponding to the (111), (200), and (220) crystal planes in the XRD curve, which proves that the Pd metal catalyst was successfully prepared by the simple impregnation reduction method. At the same time, the absence of Fe characteristic peaks in the XRD curve also indicates that the "dealloying" method successfully removed Fe from the PdFe alloy.
[0044] The obtained porous Pd metal electrode supported by flexible carbon cloth was characterized by scanning electron microscopy, and the results are as follows: Figure 6 As shown, consistent with the transmission electron microscopy (TEM) results, the scanning electron microscopy (SEM) image clearly shows a large number of spherical Pd metal particles successfully attached to the carbon cloth surface. EDS characterization also confirms the presence of Pd. EDS analysis reveals the presence of nitrogen (N) on the carbon cloth surface, indicating N doping through the nitric acid oxidation process, which also endows the carbon cloth with certain catalytic activity.
[0045] Example 5: To compare the necessity of all steps in this invention, different preparation steps were taken to obtain different electrodes, and performance comparison experiments were conducted. The effect of pretreatment on carbon cloth was compared, and the pretreated and untreated carbon cloths were named "oxidized CFC" and "CFC," respectively. The effect was achieved by changing the FeCl3 concentration in the impregnation solution (1.0 mmol·dm³). -3 and 0m mol·dm -3 To compare the effects of porous structures on the performance of Pd metal catalysts, porous Pd metal catalysts and Pd metal catalysts were named "NP Pd" and "Pd" catalysts, respectively.
[0046] like Figure 7 CFC, CFC oxide, Pd / CFC, Pd / CFC oxide, and NP Pd / CFC oxide electrodes at 1.5 mol·dm³ - 3 H2SO4 and 1.5 mol·dm -3 In H2O2 solution, the catalytic electroreduction performance of different electrode pairs was compared to verify the necessity of each operational step of the present invention. At 0.6 V, comparing the current density of different electrodes catalyzing the electroreduction of H2O2, it can be seen that the oxidation of CFCs after pretreatment exhibits certain catalytic activity, and the pretreated carbon cloth-supported Pd metal catalyst shows higher performance. Compared with 1.0 mmol·dm³ in the impregnation solution... -3 and 0 mmol·dm -3 The catalytic performance of the electrodes (NP Pd / CFC oxide, Pd / CFC oxide) prepared by FeCl3 shows that the electrode catalytic performance is higher after the "dealloying" treatment.
[0047] like Figure 8 The solution at the anodic reaction was 2.0 mol·dm³. -3 H2SO4 and 1.5 mol·dm -3 H2O2, cathode reaction solution is 3 mol·dm -3 NaOH and 0.6 mol·dm -3 In H₂O₂, at a flow rate of 5 ml / min, the performance of single cells composed of Pd / CFC, Pd / Oxide CFC, and NP Pd / Oxide CFC electrodes as cathode and anode were compared. The figures show that the single cell composed of NP Pd / Oxide CFC as both cathode and anode has a higher power density and a higher open-circuit potential.
[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A porous Pd metal electrode supported by flexible carbon cloth, characterized in that: Porous Pd metal electrodes were prepared on flexible carbon cloth substrates using an impregnation reduction method and a dealloying process. The specific preparation steps are as follows: (1) Arrange carbon in a hydrothermal reactor, add nitric acid and keep warm at 120°C for 240 min. After cooling to room temperature, wash thoroughly with deionized water and then dry in a 70°C forced-air drying oven for 3 h. (2) The pretreated carbon was immersed in a mixed solution of PdCl2 and FeCl3 for 5 min, and then dried in a 160℃ forced-air drying oven for 15 min. The dried carbon was then placed in a 0.1 mol·dm³ solution. -3 PdFe composite material was prepared on the surface of carbon cloth by chemical reduction in NaBH4 solution for 5 min. After thorough washing with deionized water, it was placed in a 6 mol·dm³ solution. -3 Fe metal in PdFe composite material is removed by HCl solution; the above operation is a cycle, repeated 2-10 times to obtain a porous Pd metal electrode supported by flexible carbon cloth.
2. The flexible carbon cloth-supported porous Pd metal electrode according to claim 1, characterized in that: The nitric acid concentration mentioned in step (1) is 65-68%, and the nitric acid in the hydrothermal reactor should be at least 1 cm above the carbon cloth to ensure complete oxidation of the carbon cloth.
3. The flexible carbon cloth-supported porous Pd metal electrode according to claim 1, characterized in that: In step (2), the concentration of PdCl2 in the mixed solution of PdCl2 and FeCl3 is 5 mmol·dm³. -3 The FeCl3 concentration was 0.5 mmol·dm³. -3 -2.0 mmol·dm -3 Repeat 6 times to obtain a porous Pd metal electrode supported by flexible carbon cloth.
4. The flexible carbon cloth-supported porous Pd metal electrode according to claim 1, characterized in that: In step (2), the FeCl3 concentration is 1.0 mmol·dm³. -3 .
5. The application of the flexible carbon cloth-supported porous Pd metal electrode as described in claim 1 in the catalytic electroreduction of H2O2.
6. The application according to claim 5, characterized in that: The specific application process is as follows: a porous Pd metal electrode supported by flexible carbon cloth is used as the working electrode, and a silver chloride electrode and a graphite rod are used as the reference electrode and counter electrode, respectively, in the range of 0.5-2.5 mol·dm³. -3 H2SO4 and 0.5-2.5 mol·dm -3 Catalytic electroreduction of H2O2 in H2O2 solution.