Preparation method and application of a pdcd catalyst

Abstract

The application provides a preparation method and application of a PdCd catalyst, and belongs to the technical field of fuel cell catalysts. The PdCd nanowire with an ordered intermetallic compound structure is directly synthesized under mild conditions through specific raw material combination and one-step hydrothermal method, and high-temperature post-treatment or template assistance is not needed, so that the process is simple and the operation is convenient. The obtained catalyst has the nanowire morphology and the ordered intermetallic compound structure, and when being used for the anode ethanol oxidation reaction of a direct ethanol fuel cell, the catalyst shows excellent catalytic activity and long-term stability. The preparation method provided by the application has wide raw material sources, mild reaction conditions and good reproducibility, and provides a new technical path for the development of a high-performance anode catalyst of a direct ethanol fuel cell.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell catalyst technology, specifically relating to a method for preparing and applying a PdCd catalyst. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Ethanol is an abundant feedstock that is easy to store, transport, and produce on a large scale, making direct ethanol fuel cells (DEFCs) a promising portable energy source. However, the performance of DEFCs is limited by the sluggish kinetics of the anodic ethanol oxidation reaction (EOR), which is one of the bottlenecks restricting the commercialization of DEFCs.

[0004] Pd-based materials are a core research focus in catalytic systems due to their excellent catalytic performance for EOR in alkaline environments and their advantages in terms of reserves and cost compared to Pt-based catalysts. However, conventional Pd-based disordered alloy catalysts are prone to active component dissolution and intermediate poisoning during long-term cycling, leading to a rapid decline in catalytic activity and stability. Constructing ordered structures to precisely control the electronic states and active sites of Pd-based catalysts has proven to be an effective way to improve catalytic performance. Compared to disordered alloys, ordered intermetallic compounds have stronger interatomic bonding forces and more stable electronic structures, which can effectively control the d-band centers of the active metal while inhibiting the aggregation and leaching of active components.

[0005] In recent years, researchers have conducted extensive studies on the preparation and electrocatalytic applications of ordered metal phase materials, involving various Pd-based ordered alloy systems. However, the synthesis conditions of existing ordered phase materials are generally quite demanding, and research on the formation of ordered intermetallic compounds between Pd and Group IIB metals is still insufficient. Exploring novel Pd-based ordered intermetallic compound systems and developing mild and controllable synthesis methods is of great significance for improving the catalytic performance of DEFCs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a PdCd catalyst.

[0007] The present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a PdCd catalyst, comprising the following steps: The palladium precursor, cadmium precursor, reducing agent, morphology control agent and solvent are mixed evenly to obtain a mixture; The mixture was subjected to a hydrothermal reaction and purified to obtain a PdCd catalyst.

[0008] A second aspect of the present invention provides a PdCd catalyst prepared by the preparation method described in the first aspect.

[0009] A third aspect of the invention provides the application of the PdCd catalyst described in the second aspect in a direct ethanol fuel cell.

[0010] A fourth aspect of the present invention provides a direct ethanol fuel cell comprising the PdCd catalyst described in the second aspect.

[0011] Compared with the prior art, the beneficial effects of the present invention are: This invention synthesizes a PdCd catalyst using a hydrothermal method. By mixing a palladium precursor, a cadmium precursor, a reducing agent, a morphology control agent, and a polyol solvent, and then carrying out a hydrothermal reaction, PdCd nanowires with an ordered intermetallic compound structure can be directly synthesized in one step under mild conditions (180-240℃). The process is simple, convenient, and easily scalable. The method utilizes a specific combination of palladium and cadmium precursors and a reducing agent, which can induce the ordered arrangement of Pd and Cd atoms at a relatively low temperature, forming an ordered intermetallic compound with strong interatomic bonding and stable electronic structure. This overcomes the drawback of conventional ordered phase material preparation requiring high-temperature annealing (typically >500℃), avoiding the sintering and agglomeration problems of nanostructures caused by high-temperature treatment. It exhibits excellent catalytic activity and long-term stability in the ethanol oxidation reaction at the anode of a direct ethanol fuel cell. Experiments show that its ethanol oxidation mass activity and specific activity are significantly higher than those of commercial Pd / C and Pt / C catalysts, and it also has superior anti-poisoning performance and cycle stability. The preparation method provided by this invention has a wide range of raw material sources, mild reaction conditions, and good reproducibility, providing a new technical path for the development of high-performance ethanol fuel cell anode catalysts. Attached Figure Description

[0012] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0013] Figure 1 These are TEM, SEM-EDS, and XRD results of the ordered PdCd nanowire (o-PdCd NWs) catalyst prepared in Example 1 of this invention. In the image, a is a low-magnification TEM image at 100 nm, b is a high-magnification TEM image at 20 nm, c is the XRD diffraction pattern, and d is the SEM-EDS pattern. Figure 2 This is a magnified TEM image of the o-PdCd NWs prepared in Example 1 of this invention; Figure 3 for Figure 2 HRTEM image of the selected area; Figure 4 These are TEM, SEM-EDS, and XRD results of the disordered PdCd nanowires (d-PdCd NWs) prepared in Comparative Example 1 of this invention. In the images, a is a low-magnification TEM image at the 100 nm scale, b is a high-magnification TEM image at the 20 nm scale, c is the XRD diffraction pattern, and d is the SEM-EDS pattern. Figure 5 These are TEM, SEM-EDS, and XRD results of the PdCd nanoparticle (PdCd NPs) catalyst prepared in Comparative Example 2 of this invention. In the figure, a is a low-magnification TEM image at 100 nm, b is a high-magnification TEM image at 20 nm, c is the XRD diffraction pattern, and d is the SEM-EDS pattern. Figure 6 The above are XPS results of the PdCd catalyst o-PdCd NWs prepared in Example 1 of this invention, where a is the total XPS spectrum, b is the high-resolution XPS spectrum of Pd 3d, and c is the high-resolution XPS spectrum of Cd 3d. Figure 7 The figures show the electrochemical performance test results of the catalysts prepared in Examples 1, 1, and 2 of this invention, compared with commercial catalysts. In the figures, a is the CO dissolution curve of each catalyst, b is the cyclic voltammogram of each catalyst in 1 M KOH and 1 M CH3CH2OH, c is the bar chart of mass activity and area ratio activity of each catalyst, and d is the chronoamperometry curve of each catalyst in 1 M KOH + 1 M CH3CH2OH solution at a fixed potential of 0.7 V (relative to RHE) for 3600 s. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, 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.

[0016] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] A typical embodiment of the present invention provides a method for preparing a PdCd catalyst, comprising the following steps: The palladium precursor, cadmium precursor, reducing agent, morphology control agent and solvent are mixed evenly to obtain a mixture; The mixture was subjected to a hydrothermal reaction and purified to obtain a PdCd catalyst.

[0018] In some embodiments, the homogenization process includes ultrasonic treatment for 70–120 min, with an ultrasonic power of 180–220 W and an ultrasonic frequency of 90–110 kHz. Ultrasonic treatment can further improve the dispersion uniformity of each component, ensuring sufficient contact and synergistic reaction of each element during the subsequent hydrothermal reaction, and avoiding problems such as irregular morphology and abnormal crystal phase caused by excessively high local component concentrations.

[0019] In some embodiments, the palladium precursor comprises palladium acetylacetonate; the cadmium precursor is cadmium acetate dihydrate. Palladium acetylacetonate exhibits good solubility and thermal stability in polyol solvents, which is beneficial for achieving uniform co-reduction of Pd and Cd. Cadmium acetate dihydrate is readily decomposed and has good reaction compatibility with the palladium precursor.

[0020] In some embodiments, the mass ratio of the palladium precursor to the cadmium precursor is 1:(0.5~1.5), preferably 1:(0.5~1.4).

[0021] In some embodiments, the reducing agent comprises glucose; the mass ratio of the palladium precursor to the reducing agent is 1:(2~9). Glucose, as a weak reducing agent, can continuously release its reducing power under mild conditions, which is beneficial for the ordered arrangement of Pd and Cd atoms rather than rapid disordered deposition, thereby promoting the formation of intermetallic compounds.

[0022] In some embodiments, the morphology control agent includes polyvinylpyrrolidone; the mass ratio of the palladium precursor to polyvinylpyrrolidone is 1:(10~15). Polyvinylpyrrolidone can selectively adsorb onto specific crystal planes, inducing anisotropic growth of crystals along a one-dimensional direction. At the same time, the steric hindrance effect formed by its long chains can effectively prevent nanowire aggregation, thereby obtaining nanowire products with uniform morphology.

[0023] In some embodiments, the solvent includes one or more of ethylene glycol, glycerol, and diethylene glycol; the mass-to-volume ratio of the palladium precursor to the solvent is 1 mg:(0.8~1.5) mL.

[0024] In some embodiments, the hydrothermal reaction is carried out at a temperature of 180–240 °C for a duration of 1–5 h. Within this temperature range, reducing agents such as glucose can continuously decompose to provide reducing power, while avoiding excessively high temperatures that could lead to nanowire breakage or aggregation; within this time range, Pd and Cd can fully react and complete the formation of an ordered structure.

[0025] In some embodiments, the purification step includes: after the hydrothermal reaction is completed, the mixture is naturally cooled to room temperature, and the precipitate is collected by centrifugation.

[0026] In some embodiments, the centrifugation conditions include: a centrifugation speed of 3000~8000 rpm and a centrifugation time of 3~10 minutes.

[0027] Another embodiment of the present invention provides a PdCd catalyst prepared by the above preparation method.

[0028] In some embodiments, the PdCd catalyst has an ordered intermetallic compound structure and is in the form of nanowires with a cross-sectional diameter of 5–20 nm. The nanowires have protrusions of varying degrees, meaning the PdCd catalyst has a larger specific surface area, thus providing more abundant catalytic active sites.

[0029] Preferably, the cross-sectional diameter of the PdCd catalyst is 8~15 nm.

[0030] A third embodiment of the present invention provides the application of the above-described PdCd catalyst in a direct ethanol fuel cell. The PdCd catalyst is used for the ethanol oxidation reaction at the anode of the direct ethanol fuel cell. Specifically, the o-PdCd NWs / C exhibits the highest current density, reaching 8.18 A·mgPd. -1 The specific activity of o-PdCd NWs / C was 2.2, 3.9, 7.9, and 6.5 times that of d-PdCd NWs / C, PdCd NPs / C, commercial Pd / C, and commercial Pt / C, respectively; the specific activity of o-PdCd NWs / C was 1.2, 1.8, 4.2, and 6.3 times that of d-PdCd NWs / C, PdCd NPs / C, commercial Pd / C, and commercial Pt / C, respectively.

[0031] A fourth embodiment of the present invention provides a direct ethanol fuel cell comprising the above-described PdCd catalyst.

[0032] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0033] The experimental reagents used in this invention are shown in Table 1 below.

[0034] Table 1 Experimental Reagents

[0035] The commercial Pt / C is sourced from Shanghai Hesen Electric Co., Ltd., with a Pt load of 20 wt.% and model HPT020; the commercial Pd / C is sourced from McLean, with a Pd load of 10 wt.% and model P821217.

[0036] The instruments used in this invention for characterization: X-ray diffractometer (XRD): SmartLab 9, manufactured by Rigaku Corporation, Japan, Cu-Kα target (λ = 0.15406 nm). Scanning range 10°~90°, used for analyzing the phase composition of samples.

[0037] Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS): A SU8010 field emission scanning electron microscope, manufactured by Hitachi, Japan, operating at 15 kV, was used to characterize the surface morphology of samples. The energy dispersive spectroscopy (EDS) instrument equipped on the SU8010 scanning electron microscope was used to analyze the content of Pd and Cd elements on the catalyst surface.

[0038] Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM): JEM-1011 transmission electron microscope, manufactured by Rigaku Corporation, Japan, with an accelerating voltage of 100 kV, was used to observe the overall morphology of the catalyst. JEOL JEM-2100plus high-resolution transmission electron microscope, manufactured by Nippon Electron Ltd., USA, with an accelerating voltage of 200 kV, was used to observe the lattice fringes of the catalyst and measure the interplanar spacing.

[0039] X-ray photoelectron spectroscopy (XPS): Collected on a Thermo Fisher Scientific spectrometer, using Al Kα radiation as the excitation source to observe the valence states of elements on the material surface.

[0040] Inductively Coupled Plasma Mass Spectrometry (ICP-MS): Agilent ICP-MS7850 inductively coupled plasma mass spectrometer, manufactured by Agilent Technologies, Inc., USA, is used for the quantitative analysis of elements in catalysts.

[0041] Electrochemical workstation: CHI660E, manufactured by Shanghai Chenhua Instrument Co., Ltd. Used for testing the EOR performance of catalysts.

[0042] Electrochemical performance testing method of this invention: All electrochemical data were measured using a Shanghai Chenhua CHI660e electrochemical workstation. In the three-electrode system, a saturated calomel electrode (SCE) was used as the reference electrode, and a carbon rod as the counter electrode. In the EOR test, a glassy carbon electrode coated with 2.5 μg of catalyst was used as the working electrode. Before the test, the catalyst (1 mg) was ultrasonically dispersed in isopropanol and Nafion (5 wt%) solution to prepare a homogeneous catalyst ink with a concentration of 2.5 mg / ml. To ensure uniform catalyst loading, the noble metal loading of the catalyst was 2.5 μg. The electrochemical active area (ECSA) of all catalysts was determined by CO dissolution curve analysis. The CO dissolution experiment was conducted at room temperature in 0.1 M HClO4 solution at a scan rate of 20 mV·s. -1 The potential range was 0 V to 1.3 V (relative to the RHE electrode). In the CO dissolution measurement, CO gas (99.99%) was bubbled in an open circuit in 0.1 M HClO4 solution for 30 min. The electrode was rapidly transferred to fresh 0.1 M HClO4 solution, and two cycles were recorded: the first cycle was CO dissolution voltammetry, and the second cycle was performed at room temperature at 20 mV s. -1 The scanning rate verified that there was no residual CO in the solution. The CO dissolution peak can also be used to determine the specific surface area. The ECSA of Pd in ​​the working electrode was calculated using formula (1).

[0043] (1) in, It is the amount of oxidation charge of CO. It is the CO conversion factor. It is the Pd loading on the electrode.

[0044] Meanwhile, in the performance testing of the catalyst for the electrocatalytic oxidation of ethanol (EOR), the electrolyte was 1 M KOH + 1 M CH3CH2OH, the scan range was 0.3–1.2 V, and the scan rate was 50 mV s. -1 The maximum peak current value during the positive sweep of the CV curve was normalized by the mass of the catalyst and ECSA, respectively, to obtain the mass activity and specific activity of the catalyst. To evaluate the stability of the catalyst, long-cycle cyclic voltammetry and chronoamperometry (CA) were used for assessment.

[0045] Example 1 A method for preparing a PdCd catalyst includes the following steps: 7.6 mg Pd(acac)₂, 6.7 mg Cd(Ac)₂·2H₂O, 60 mg glucose, 100 mg polyvinylpyrrolidone (PVP), and 8 ml ethylene glycol were mixed and ultrasonicated at 200 W and 100 kHz for 90 min to achieve uniform dispersion. The resulting homogeneous solution was then placed in a reaction vessel and maintained at 210 °C for 2 h. After cooling to room temperature, the suspension containing the precipitate was transferred, balanced, and centrifuged at 5000 rpm for 5 min for solid-liquid separation. After centrifugation, the supernatant was removed, and the desired centrifuged precipitate was collected to obtain the PdCd catalyst, which is o-PdCdNWs.

[0046] Example 2 A method for preparing a PdCd catalyst includes the following steps: 7.6 mg Pd(acac)₂, 6.7 mg Cd(Ac)₂·2H₂O, 60 mg glucose, 100 mg PVP, and 8 ml ethylene glycol were mixed and ultrasonicated at 200 W and 100 kHz for 90 min to achieve uniform dispersion. The resulting homogeneous solution was then placed in a reaction vessel and maintained at 230 °C for 2 h. After cooling to room temperature, the precipitate was separated by centrifugation to obtain the PdCd catalyst, which was o-PdCd NWs-1.

[0047] Example 3 A method for preparing a PdCd catalyst includes the following steps: 7.6 mg Pd(acac)₂, 10.64 mg Cd(Ac)₂·2H₂O, 60 mg glucose, 100 mg PVP, and 8 ml ethylene glycol were mixed and ultrasonicated at 200 W and 100 kHz for 90 min to achieve uniform dispersion. The resulting homogeneous solution was then placed in a reaction vessel and maintained at 210 °C for 2 h. After cooling to room temperature, the precipitate was separated by centrifugation to obtain the PdCd catalyst, which was o-PdCd NWs-2.

[0048] Comparative Example 1 A method for preparing a disordered PdCd catalyst includes the following steps: 4.4 mg PdCl2, 4.6 mg CdCl2·xH2O, 72 mg ascorbic acid, 100 mg PVP, and 8 ml ethylene glycol were mixed and ultrasonicated at 200 W and 100 kHz for 90 min to achieve uniform dispersion. The resulting homogeneous solution was then placed in a reaction vessel and maintained at 210 °C for 5 h. After cooling to room temperature, the precipitate was separated by centrifugation to obtain d-PdCd NWs.

[0049] Comparative Example 2 A method for preparing a PdCd nanoparticle catalyst includes the following steps: 7.6 mg Pd(acac)₂, 6.7 mg Cd(Ac)₂·2H₂O, 72 mg ascorbic acid, 100 mg PVP, and 8 ml ethylene glycol were mixed and ultrasonicated at 200 W and 100 kHz for 90 min to achieve uniform dispersion. The resulting homogeneous solution was then placed in a reaction vessel and maintained at 210 °C for 5 h. After cooling to room temperature, the precipitate was separated by centrifugation to obtain PdCdNPs.

[0050] Test Example 1 The morphology of the synthesized samples was characterized using transmission electron microscopy (TEM). For example... Figure 1 As shown in figures a and b, o-PdCd NWs exhibit a bent nanowire structure with a cross-sectional diameter of approximately 10 nm, and the nanowires display protrusions of varying degrees. This indicates that o-PdCd possesses a larger specific surface area, thus providing more abundant catalytic active sites. To investigate the crystal structure of o-PdCd, XRD measurements were performed on the o-PdCd NWs. Figure 1 As shown in c, the XRD pattern of o-PdCd NWs shows that the diffraction peaks at 38.957°, 42.193°, 50.373°, 61.344°, 67.859°, 74.884°, 83.217°, and 87.002° correspond to the (111), (200), (002), (220), (202), (311), (222), and (302) planes of body-centered tetragonal (bct) PdCd (JCPDS No. 06-0570), and there are no other impurity peaks, indicating that well-crystallized ordered intermetallic compound PdCd nanowires were successfully synthesized. Figure 1 The d in the image represents the SEM-EDS spectrum of o-PdCd NWs, and analysis confirms the presence of both Pd and Cd elements. Figure 1 The value of 'd' in the figure shows that the atomic percentage of Pd:Cd is 51.4:48.6. This also satisfies the consistency of the Pd and Cd feed ratio, proving that the reaction between Pd and Cd is complete. Figure 2To obtain a TEM image magnified 30,000 times, high-resolution transmission electron microscopy (HRTEM) was used to further observe the atomic arrangement of o-PdCd NWs in the selected area. Figure 3 As shown, the HRTEM image reveals that the lattice fringes of o-PdCd NWs are clearly visible, with a crystal plane spacing of 0.231 nm, corresponding to the (111) crystal plane of body-centered tetragonal PdCd, further confirming the formation of an ordered intermetallic compound.

[0051] The TEM, SEM-EDS, and XRD results of the PdCd catalyst d-PdCd NWs prepared in Comparative Example 1 of this invention are as follows: Figure 4 As shown, Figure 4 Figures a and b show TEM images of d-PdCd NWs at different magnifications. As can be seen from the figures, compared with o-PdCd NWs, d-PdCd has a nanowire morphology with smooth lines. The lower specific surface area results in fewer active sites, which in turn leads to poorer catalytic performance. Figure 4 The diffraction peak shown in c is highly consistent with the characteristic peak of Pd (JCPDS No. 46-1043), and the diffraction peak is shifted relative to the standard Pd, indicating that Cd atoms randomly replace Pd lattice sites, thus forming a disordered alloy. Figure 4 The image shows the SEM-EDS of d-PdCd NWs, with an atomic percentage of Pd:Cd of 52.5:47.5.

[0052] The TEM, SEM-EDS, and XRD results of the PdCd catalyst PdCd NPs prepared in Comparative Example 2 of this invention are as follows: Figure 5 As shown, Figure 5 a and b in the figure show the morphology of PdCd NPs. Figure 5 The XRD pattern of c in the sample shows diffraction peaks that correspond to those of PdCd (JCPDS No. 06-0570), but with lower intensity, indicating poor crystallinity of PdCd NPs. Furthermore, compared with the characteristic peaks of Pd (JCPDS No. 46-1043), a shift occurs, indicating the presence of a pure Pd phase. Therefore, PdCd NPs exhibit a coexistence of bct phase PdCd and pure Pd phases. Figure 5 The SEM-EDS results for d in the image show that the atomic percentages of Pd:Cd are 51.3:48.7.

[0053] To investigate the surface elemental valence states of PdCd, 1 mg of o-PdCd NWs, 1 mg of d-PdCd NWs, 1 mg of PdCd NPs, and 3 mg of Vulcan XC-72R C were sonicated in ethanol for 90 min, followed by centrifugation and natural air drying to obtain o-PdCd NWs / C, d-PdCd NWs / C, and PdCd NWs / C, which were then subjected to XPS testing. Figure 6 In the figure, 'a' represents the XPS full spectrum of o-PdCdNWs / C. As can be seen from the figure, o-PdCd NWs are mainly composed of Pd 3d and Cd 3d, which is consistent with the SEM-EDS results. Figure 1 (d) Figure 6 Figures b and c show high-resolution spectra of Pd 3d and Cd 3d in each catalyst. Figure 6 As shown in b, the high-resolution spectrum of Pd 3d contains four characteristic peaks, with the peaks at 335.7 eV and 341.0 eV belonging to the metallic state of Pd. 0 . Pd in ​​o-PdCd NWs (335.0 eV and 340.28 eV), d-PdCd NWs (334.98 eV and 340.18 eV), PdCdNPs (334.8 eV and 340.08 eV) 0 The combination of Pd and Pd in ​​commercial Pd / C 0 The binding energies of all NWs shifted towards lower binding energies, with o-PdCd NWs showing the smallest negative shift. This negative shift at the d-band center is key to the excellent catalytic activity of o-PdCd NWs in EOR. Figure 6 The 'c' in the spectrum corresponds to the high-resolution spectrum of Cd 3d, and its characteristic peaks are attributed to Cd. 0 and Cd 2 + Furthermore, the Cd 3d peak position of o-PdCd NWs / C also shows a negative shift compared to d-PdCd NWs and PdCd NPs, which corroborates the shift results of Pd 3d. This fully demonstrates that there is a significant electronic regulation effect between Pd and Cd, which optimizes the electronic structure and is one of the important reasons for the improvement of catalytic performance.

[0054] Test Example 2 Electrochemical performance testing The EOR performance of the catalyst was studied in depth. Figure 7 Figure 'a' shows the CV curves of different catalysts in 0.1 M HClO4, with a scan rate of 20 mV / s. -1A CO dissolution curve was obtained by scanning within the range of 0 V to 1.3 V (relative to the RHE electrode), and the electrochemical active area of ​​the prepared catalyst was calculated from this curve. The ECSA value of o-PdCd NWs / C was 66.4 m. 2 ·g -1 Higher than d-PdCd NWs / C (36.5 m 2 ·g -1 ), PdCd NPs / C (31.2 m 2 ·g -1 ), Commercial Pd / C (35.8m 2 ·g -1 ) and commercial Pt / C (64.1 m 2 ·g -1 ). Figure 7 Figure b shows the CV plots for the catalytic oxidation of ethanol using all catalysts, with an electrolyte of 1 M KOH + 1 M CH3CH2OH and a scan rate of 50 mV / s. -1 The scanning range was 0.3 V to 1.2 V. Among them, o-PdCd NWs / C exhibited the highest current density, reaching 8.18 A·mgPd. -1 The values ​​are d-PdCd NWs / C (3.78 A·mg). Pd -1 ), PdCd NPs / C (2.1 A·mg) Pd -1 Commercial Pd / C (1.04 A·mg) Pd -1 ) and commercial Pt / C (1.25 A·mg Pt -1 2.2, 3.9, 7.9 and 6.5 times () Figure 7 (b) Meanwhile, the specific activity of o-PdCd NWs / C was also the highest, reaching 12.3 mA·cm⁻¹. -2 The values ​​are d-PdCd NWs / C (10.4 mA·cm⁻¹). -2 PdCd NPs / C (6.73 mA·cm) -2 ), commercial Pd / C (2.91 mA·cm⁻¹) -2 ) and commercial Pt / C (1.95 mA·cm -2 ) is 1.2, 1.8, 4.2 and 6.3 times that of ). Figure 7Figure c shows a comparison of the mass activity and area activity of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 with those of commercial Pd / C. The results show that the mass activity and area activity of the o-PdCd NWs / C catalyst prepared in this invention are significantly higher than those of the comparative samples and commercial catalysts, exhibiting the best electrocatalytic performance.

[0055] Long-term durability is also important for evaluating the electrocatalytic performance of catalysts. The long-term stability of the prepared o-PdCd NWs, d-PdCd NWs, PdCd NPs, commercial Pd / C, and commercial Pt / C catalysts was investigated by chronoamperometry (CA) in a 1 M KOH + 1 M CH3CH2OH solution at a scan potential of 0.7 V (relative to the RHE electrode) for 3600 s. Figure 7 (d) After a long cycle of 3600 s, o-PdCd NWs still have the highest current density, which means that o-PdCd NWs / C not only have the highest catalytic activity, but also have better long-range stability. Its unique ordered structure is the key to improving catalytic activity and stability.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a PdCd catalyst, characterized by, Includes the following steps: The palladium precursor, cadmium precursor, reducing agent, morphology control agent and solvent are mixed evenly to obtain a mixture; The mixture was subjected to a hydrothermal reaction and purified to obtain a PdCd catalyst. The palladium precursor is palladium acetylacetonate; the cadmium precursor is cadmium acetate dihydrate. The reducing agent is glucose; The morphology control agent is polyvinylpyrrolidone; The hydrothermal reaction is carried out at a temperature of 180~240℃ for a time of 1~5 h. The PdCd catalyst has an ordered intermetallic compound structure and exhibits a nanowire structure. The mass ratio of the palladium precursor to the cadmium precursor is 1:(0.5~1.5); The mass ratio of the palladium precursor to the reducing agent is 1:(2~9).

2. The production method according to claim 1, wherein The mass ratio of the palladium precursor to polyvinylpyrrolidone is 1:(10~15).

3. The production method according to claim 1, wherein The solvent includes one or more of ethylene glycol, glycerol, and diethylene glycol; The mass-to-volume ratio of the palladium precursor to the solvent is 1 mg:(0.8~1.5) mL.

4. The PdCd catalyst prepared by the preparation method according to any one of claims 1-3.

5. The application of the PdCd catalyst according to claim 4 in a direct ethanol fuel cell.

6. A direct ethanol fuel cell characterized by comprising: It includes the PdCd catalyst of claim 4.

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