CuO / PdO@Pd-C heterojunction nanomaterial with built-in electric field enhancement and application thereof

Abstract

This invention discloses a CuO / PdO@Pd-C heterojunction nanomaterial with a built-in electric field enhancement and its applications, belonging to the field of nanomaterials technology. This CuO / PdO@Pd-C heterojunction nanomaterial is prepared by a solvothermal method using PdCl2·xH2O, CuCl2·2H2O, and anhydrous phloroglucinol as raw materials. The CuO / PdO@Pd-C heterojunction nanomaterial of this invention exhibits excellent electrocatalytic hydrogen evolution performance, particularly demonstrating excellent catalytic activity and stability across the entire pH range and in natural seawater media. This invention provides a new approach for developing low-cost, high-activity non-platinum-based hydrogen evolution electrocatalysts, and has significant scientific value and broad application prospects in fields such as renewable energy hydrogen production, seawater resource utilization, and green energy storage.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a CuO / PdO@Pd-C heterojunction nanomaterial with built-in electric field enhancement and its applications. Background Technology

[0002] Hydrogen energy, as an ideal clean energy carrier, boasts advantages such as high energy density, zero pollution, and zero carbon emissions, and is considered one of the most promising energy sources for replacing fossil fuels. Utilizing renewable energy to drive water electrolysis for hydrogen production is a crucial pathway to achieving green hydrogen production. The water electrolysis process involves two half-reactions: the oxygen evolution reaction at the anode and the hydrogen evolution reaction at the cathode. However, both reactions suffer from sluggish kinetics, requiring highly efficient electrocatalysts to reduce overpotential and thus improve energy conversion efficiency. Currently, platinum-based materials are considered the most effective catalysts for the hydrogen evolution reaction. However, the high cost and scarcity of platinum severely restrict its large-scale industrial application. To reduce catalyst costs, researchers are dedicated to developing non-precious metal catalysts or strategies to reduce the amount of precious metals used. Among these, combining precious metals with abundant transition metals to construct heterostructures can not only effectively reduce the precious metal loading but also leverage the unique electronic structure and synergistic effects of transition metals to enhance catalytic performance, making it a current research hotspot.

[0003] Transition metals (such as copper, cobalt, nickel, and iron) possess advantages such as low cost, abundant resources, and tunable d-orbital electrons, demonstrating great potential in the field of electrocatalysis. However, single transition metal oxides often exhibit poor conductivity or insufficient catalytic activity. Combining them with small amounts of noble metals (such as platinum, palladium, and ruthenium) to form heterostructures can induce a built-in electric field through electronic coupling at the interface, optimizing the electronic structure of active sites and regulating the hydrogen adsorption free energy, thereby significantly improving the hydrogen evolution reaction performance. For example, Sun et al. successfully prepared Cu3Pd atomic clusters anchored on α-MoC by pyrolyzing a Pd-modified NENUS metal-organic framework precursor under a nitrogen atmosphere. 1-x Composite electrocatalysts on nanoparticle surfaces (Cu3Pd@α-MoC) 1-x / C) (SunX R, Ge BX, Xue SK, et al. Lattice-matched Cu3Pd@α-MoC 1-xHeterointerfaces boost alkaline hydrogen evolution by accelerating water dissociation and optimizing hydrogen adsorption energy [J]. Applied Catalysis B-Environment and Energy, 2026, 386.). This catalyst utilizes lattice-matched heterointerfaces to promote electron transfer from Cu3Pd to α-MoC. 1-x The transfer optimized the d-band center of Pd, resulting in excellent hydrogen evolution activity (10 mA·cm⁻¹) in 1.0 M KOH. -2 The overpotential is 56mV, and it exhibits excellent long-term stability (over 500 hours). This strategy retains the high reactivity of precious metals while significantly reducing the amount of precious metals used, thus balancing performance and cost.

[0004] Palladium (Pd), a member of the platinum group metals, is cheaper than platinum and abundant in nature. It possesses excellent hydrogen evolution activity and corrosion resistance, making it an ideal candidate to replace platinum. However, the activity and stability of pure palladium-based catalysts in alkaline media, especially in complex seawater environments, still need improvement. Furthermore, freshwater resources on Earth are becoming increasingly scarce, and large-scale water electrolysis for hydrogen production will put enormous pressure on these limited resources. Seawater accounts for approximately 97% of the Earth's total water volume, and electrocatalytic seawater hydrogen production provides a new pathway for low-cost, clean energy conversion. However, natural seawater contains a large number of impurity ions (such as Cl-). - Na + Mg 2+ Ca 2+ Certain substances (such as chlorine, chlorine, and chlorine) can poison the active sites of the catalyst and cause electrode corrosion, severely limiting the catalyst's stability in seawater. Currently, many research tests are conducted primarily in alkaline pure water or hydrogenation reaction systems, and the long-term stability and high efficiency of hydrogen evolution performance in real seawater have not yet been fully verified. Therefore, developing Pd-based hydrogen evolution catalysts that exhibit both high activity and high stability across the entire pH range and in seawater remains a significant challenge. Summary of the Invention

[0005] One objective of this invention is to provide a CuO / PdO@Pd-C heterojunction nanomaterial, which is prepared by a solvothermal method using PdCl2·xH2O, CuCl2·2H2O, and anhydrous phloroglucinol as raw materials. The preparation method is as follows: PdCl2·xH2O, CuCl2·2H2O, anhydrous phloroglucinol, octadecene and oleylamine are uniformly mixed and reacted in a one-pot solvothermal method. After the reaction is completed, the heterojunction nanomaterial is obtained by washing and separation.

[0006] Furthermore, the molar ratio of PdCl2·xH2O, CuCl2·2H2O, and anhydrous phloroglucinol is 2:0.5:0.1.

[0007] Furthermore, the solvent used in the reaction is oleylamine and octadecene.

[0008] Furthermore, the reaction conditions are a reaction temperature of 210 °C and a reaction time of 5 h.

[0009] Furthermore, a programmed temperature rise to 210 °C was employed, specifically at 1 °C / min increments. -1 The heating rate is increased to 210℃.

[0010] Furthermore, after the reaction is completed, the mixture of equal volumes of cyclohexane and anhydrous ethanol is used for washing to remove unreacted impurities and surface-adsorbed organic matter.

[0011] The second objective of this invention is to provide the application of the above-mentioned CuO / PdO@Pd-C heterojunction nanomaterial as a catalyst in the electrolysis of water to produce hydrogen, especially in natural seawater and electrolytes of different pH values.

[0012] The CuO / PdO@Pd-C heterojunction preparation process of this invention is simple and efficient, with mild reaction conditions, easy to scale up for production, and requires no complex post-processing steps. The obtained CuO / PdO@Pd-C heterojunction exhibits excellent electrocatalytic hydrogen evolution performance, especially demonstrating excellent catalytic activity and stability across the entire pH range and in natural seawater media. This superior performance is mainly attributed to the strong built-in electric field and synergistic effect between PdO and CuO, which not only optimizes the hydrogen adsorption free energy but also improves the charge transfer efficiency. This invention provides a new approach for developing low-cost, highly active non-platinum-based hydrogen evolution electrocatalysts, and has significant scientific value and broad application prospects in fields such as renewable energy hydrogen production, seawater resource utilization, and green energy storage.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention successfully constructed a CuO / PdO@Pd-C heterojunction with a built-in electric field using a one-pot solvothermal method. Utilizing the work function difference between the PdO and CuO components, a built-in electric field is induced at the heterojunction interface, optimizing the interfacial charge transfer characteristics and regulating the hydrogen adsorption free energy. Simultaneously, by introducing the inexpensive transition metal copper, the amount of the noble metal palladium is reduced, achieving a balance between high activity and low cost. Electrochemical tests showed that this catalyst, in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M PBS, exhibited a 10 mA·cm⁻¹ energy dissipation rate. -2The overpotentials at the specified current densities were only 25 mV, 23 mV, and 12 mV, respectively, demonstrating excellent hydrogen evolution performance across all pH levels. Furthermore, this catalyst exhibited excellent hydrogen evolution performance at 30 mA·cm⁻¹ in the aforementioned three electrolytes. -2 The stability at current densities can reach 250 hours, 1175 hours and 350 hours, respectively, which is far superior to most palladium-based catalysts reported in the existing literature.

[0014] 2. The CuO / PdO@Pd-C heterojunction prepared in this invention also exhibits excellent catalytic activity in simulated seawater (1 M KOH + 0.5 M NaCl), with a catalytic activity of 10 mA·cm⁻¹. -2 The overpotential is only 25 mV. This is especially true at high current densities of 500 mA·cm⁻¹. -2 Under these conditions, the catalyst can operate stably for over 700 hours without significant performance degradation, demonstrating excellent potential for industrial applications. In particular, this invention tested real natural seawater collected from the South China Sea, and the results showed that the CuO / PdO@Pd-C heterojunction maintained excellent hydrogen evolution activity in real seawater. This research provides a new material option for green hydrogen production utilizing abundant seawater resources.

[0015] 3. The preparation method of this invention employs a one-pot solvothermal process, which is simple, reproducible, and yields high output, making it suitable for large-scale production. The resulting product exhibits a clear heterogeneous interface structure and uniform particle size distribution, which is beneficial for fully utilizing its catalytic performance.

[0016] 4. This invention achieves precise control over the electronic structure of the catalyst through a heterogeneous interface built-in electric field strategy, providing a new approach for designing high-performance, low-cost transition metal-noble metal composite hydrogen evolution catalysts. This material has broad application prospects in renewable energy hydrogen production, seawater resource utilization, and green energy storage. Attached Figure Description

[0017] Figure 1 The images show the SEM, TEM, and elemental mapping of CuO / PdO@Pd-C in Example 1 of this invention.

[0018] Figure 2 The image shows the XRD pattern of CuO / PdO@Pd-C in Example 1 of this invention. Figure 3 This is the XPS image of CuO / PdO@Pd-C in Embodiment 1 of the present invention.

[0019] Figure 4 This is a UPS diagram of CuO / PdO@Pd-C in Embodiment 1 of the present invention.

[0020] Figure 5This is a comparison chart of the electrochemical performance of CuO / PdO@Pd-C across the entire pH range in Example 1 of this invention.

[0021] Figure 6 This is the chronoamperometry curve of CuO / PdO@Pd-C in Example 1 of the present invention over the entire pH range.

[0022] Figure 7 The figure shows the chronocurrent curve of CuO / PdO@Pd-C in simulated seawater in Example 1 of this invention.

[0023] Figure 8 The figure shows the hydrogen evolution polarization curves of CuO / PdO@Pd-C in simulated seawater and alkaline seawater in Example 1 of this invention. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0026] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1

[0027] A method for preparing a CuO / PdO@Pd-C heterojunction includes the following steps: At room temperature, 0.3547 g (2 mmol) PdCl2·xH2O, 0.08524 g (0.5 mmol) CuCl2·2H2O, 0.0504 g (0.4 mmol) anhydrous phloroglucinol, 8 mL oleylamine, and 2 mL octadecene are weighed and added to a dry and clean single-necked flask. The mixture is ultrasonically dispersed for 30 min, and then dispersed in an oil bath at 1 ℃ for 1 min using programmed temperature control technology. -1 The temperature was increased to 210 °C at a rising rate and held at 210 °C for 5 h. After cooling to room temperature, the product was washed four times with an equal volume mixture of anhydrous ethanol and cyclohexane. The solid was separated by centrifugation. After washing, a black product was obtained and dried in a vacuum drying oven at 60 °C for 12 h to obtain CuO / PdO@Pd-C heterojunction.

[0028] The precursor was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental mapping. The results are as follows: Figure 1As shown, SEM revealed that the prepared precursor had a regular nanocluster morphology. Elemental mapping analysis showed that the prepared precursor was composed of Pd, Cu, and Cl. Further magnified TEM revealed that the CuO / PdO@Pd-C heterojunction had numerous heterocrystalline facets, effectively increasing the number of catalytically active sites. Furthermore, the large specific surface area of ​​the nanocluster structure assembled from small nanoparticles is also an important factor contributing to its excellent HER performance.

[0029] like Figure 2 As shown in the figure, the XRD test results show that the material synthesized in this embodiment is a CuO / PdO@Pd-C heterojunction, which is mainly composed of monoclinic CuO (PDF#97-004-3179) and cubic PdO (PDF#97-007-7650), with the main crystal planes being the 200 crystal plane of CuO and the 220 crystal plane of PdO.

[0030] like Figure 3 As shown, XPS photoelectron spectroscopy characterization reveals that the Pd 3d XPS spectrum can be decomposed into four peaks. The peaks at 335.41 and 337.96 eV correspond to Pd 3d 5 / 2, and the peaks at 340.73 and 343.03 eV correspond to Pd 3d 3 / 2. The peaks at 337.96 and 343.03 eV are attributed to divalent palladium (Pd 3d 5 / 2). 2+ The peaks at 335.41 and 340.73 eV correspond to zero-valent palladium (Pd). 0 This indicates that the Pd element is mainly composed of Pd 2+ and Pd 0 It exists in the form of Cu 2p orbital. The Cu 2p orbital consists of four peaks, with the peaks at 954.56 and 951.66 eV corresponding to Cu 2p 1 / 2, and the peaks at 934.31 and 931.77 eV corresponding to Cu 2p 3 / 2. The peaks at 954.56 and 934.31 eV belong to divalent copper (Cu). 2+ The peaks at 951.66 and 931.77 eV correspond to 0-valent copper (Cu). 0 This indicates that Cu is mainly composed of Cu. 2+ and Cu 0 It exists in the form of O 1s orbital, which consists of two peaks at binding energies of 530.45 eV, 532.45 eV, and 535.3 eV, corresponding to the metal-oxygen bond, hydroxyl-oxygen bond, and 3p bond of PdO, respectively. 3 / 2 Energy levels. These results all indicate that this embodiment prepared CuO / PdO@Pd-C heterojunction nanospheres.

[0031] like Figure 4As shown, due to the different work functions (Φ) and band gap energies (Eg) between the CuO@C and PdO@Pd-C phases, a built-in electric field is formed at the interface, optimizing the electronic structure of CuO / PdO@Pd-C. Furthermore, the work function (Φ) of the material was measured using ultraviolet photoelectron spectroscopy (UPS), which helps to reveal the variation law of the electronic band structure in the CuO / PdO@Pd-C mixed phase. Figure 4 As shown, the corresponding Φ values ​​for CuO@C and PdO@Pd-C are estimated to be 2.4 eV and 4.39 eV, respectively (Φ values ​​are calculated using the equation Φ = 21.2 eV − Ecutoof + EF). Based on the above results, the possible interaction mechanism of CuO / PdO@Pd-C composed of CuO@C and PdO@Pd-C is as follows: Figure 4 As shown, when CuO@C and PdO@Pd-C directly contact to form a heterojunction, the spontaneous difference in band potential energy drives electrons from the CuO@C phase with the lower Fermi level to the PdO@Pd-C phase until the Fermi levels of the two materials reach equilibrium at the heterojunction interface. Subsequently, the band structure of the two sets of samples was characterized using UV-Vis DRS spectroscopy. All samples exhibited optical absorption characteristics in the visible region of the electromagnetic spectrum. The estimated band gap energies were calculated based on the Wood-Tauc model using the previous equations. Due to the difference in Φ and Eg values ​​between the two phases, a built-in electric field is generated at the CuO / PdO@Pd-C heterojunction interface. This means that designing a built-in electric field effect can significantly promote charge separation / transport and electrode dynamics. Comparative Example 1

[0032] At room temperature, 0.08867 g (0.5 mmol) of PdCl2·xH2O, 0.0504 g (0.4 mmol) of anhydrous phloroglucinol, 8 mL of oleylamine, and 2 mL of octadecene were weighed and added to a clean, dry single-necked flask. The mixture was ultrasonically dispersed for 30 min, and then heated to 210 °C in an oil bath at a heating rate of 1 °C / min using a temperature-programmed control technique. The mixture was then held at 210 °C for 5 h. After cooling to room temperature, the solid was washed four times with an equal volume mixture of anhydrous ethanol and cyclohexane. The solid was then centrifuged to separate the solid. The resulting black product was dried in a vacuum oven at 60 °C for 12 h to obtain PdO@Pd-C. Comparative Example 2

[0033] At room temperature, 0.4262 g (2.5 mmol) CuCl2·2H2O, 0.0504 g (0.4 mmol) anhydrous phloroglucinol, 8 mL oleylamine, and 2 mL octadecene were weighed and added to a dry, clean single-necked flask. The mixture was ultrasonically dispersed for 30 min, and then, using programmed temperature control, dispersed in an oil bath at 1 °C / min.-1 The temperature was increased to 210 °C at a rising rate and held at 210 °C for 5 h. After cooling to room temperature, the product was washed four times with an equal volume mixture of anhydrous ethanol and cyclohexane. The solid was separated by centrifugation. After washing, a black product was obtained and dried in a vacuum drying oven at 60 °C for 12 h to obtain CuO@C. Test case

[0034] The electrochemical performance of the CuO / PdO@Pd-C heterojunction obtained in Example 1, the PdO@Pd-C obtained in Comparative Example 1, the CuO@C obtained in Comparative Example 2, and the commercial 20% Pt / C catalyst were tested. The test method is as follows: Before the experiment, 5 mg of the test substance was weighed and dispersed in 800 μL of anhydrous ethanol. After uniform dispersion, 150 μL of double-distilled water and 50 μL of 5 wt% naphthol solution were added to obtain a suspension of 5 mg / mL. A glassy carbon electrode with a diameter of 3 mm was ground to a mirror finish using Al2O3, rinsed clean with double-distilled water, and dried in an oven at 45 ℃ for later use. The 5 μL suspension was dropped onto the electrode surface ten times and dried in an oven to obtain the modified electrode.

[0035] like Figure 5 As shown, HER performance tests reveal that in 1 M KOH (pH=14), the CuO / PdO@Pd-C heterojunction performs well at a current density of 10 mA cm⁻¹. -2 At that time, its overpotential was 25 mV and the Tafel slope was 30 mV dec. -1 It is much smaller than PdO@Pd-C (overpotential of 46 mV, Tafel slope of 72 mV dec) -1 ) and CuO@C (overpotential of 495 mV, Tafel slope of 200 mV dec) -1 In 0.5 M H₂SO₄ (pH=0), the CuO / PdO@Pd-C heterojunction operates at a current density of 10 mAcm⁻¹. -2 At that time, its overpotential was 23 mV and the Tafel slope was 24 mV dec. -1 Much smaller than PdO@Pd-C (overpotential of 60 mV, Tafel slope of 80 mV dec) -1 ) and CuO@C (overpotential of 343 mV, Tafel slope of 130 mV dec) -1 In 1 M PBS, the CuO / PdO@Pd-C heterojunction at a current density of 10 mA cm⁻¹ -2 At that time, its overpotential was 12 mV and the Tafel slope was 29 mV dec. -1 It is much smaller than PdO@Pd-C (overpotential of 365 mV, Tafel slope of 153 mV dec)-1 ) and CuO@C (overpotential of 628mV, Tafel slope of 257 mV dec) -1 This demonstrates that the CuO / PdO@Pd-C heterojunction is comparable to commercial Pt / C across the entire pH range (overpotential of 14 mV in 1 M KOH, Tafel slope of 20 mV dec). -1 The overpotential in 0.5 M H₂SO₄ is 43 mV, and the Tafel slope is 43 mV dec. -1 The overpotential in 1 M PBS was 22 mV, and the Tafel slope was 41 mVdec. -1 ).

[0036] like Figure 5 As shown, to evaluate the hydrogen evolution performance of the catalyst across the entire pH range, linear sweep voltammetry (LSV) tests were performed using a Shanghai Chenhua Electrochemical Workstation 660E in a standard three-electrode system. In the tests, a saturated calomel electrode (calibrated before use), a graphite rod, and a glassy carbon electrode loaded with the catalyst were used as the reference, counter, and working electrodes, respectively. In a 1 mM MKOH solution (pH=14), the LSV was measured at 5 mV / s. -1 The scan rate was tested in the range of -0.9 to -1.7 V vs. SCE. The results showed that the CuO / PdO@Pd-C heterojunction performed well at a current density of 10 mA cm⁻¹. -2 The overpotential at that time was 25 mV, and the Tafel slope was 30 mV dec. -1 Its performance is far superior to PdO@Pd-C (overpotential 46 mV, Tafel slope 72 mV dec). -1 ) and CuO@C (overpotential 495 mV, Tafel slope 200 mV dec) -1 In 0.5 M H₂SO₄ (pH=0) solution, the test scan range was -0.1 to -0.9 V vs. SCE. The results showed that the overpotential of the CuO / PdO@Pd-C heterojunction at 10 mA·cm⁻² was 23 mV, and the Tafel slope was 24 mV dec. -1 It is also significantly superior to PdO@Pd-C (overpotential 60 mV, Tafel slope 80 mV dec) -1 ) and CuO@C (overpotential 343 mV, Tafel slope 130 mV dec) -1 In 1 M PBS (pH=7) solution, the test scan range was -0.5 to -1.3 V vs. SCE. The results showed that the CuO / PdO@Pd-C heterojunction had an overpotential as low as 12 mV and a Tafel slope of 29 mV at 10 mA cm⁻². -1It is much lower than that of PdO@Pd-C (overpotential 365 mV, Tafel slope 153 mVdec) -1 ) and CuO@C (overpotential 628 mV, Tafel slope 257 mV dec) -1 All LSV tests described above were performed with 85% iR compensation on the polarization curves, and the pH values ​​of all electrolytes were precisely calibrated using a pH meter. Potentials were calculated according to formula E. RHE = E SCE +0.241 +0.059 pH is converted to a reversible hydrogen electrode potential. The Tafel slope is derived mathematically from the LSV curve. In summary, the CuO / PdO@Pd-C heterojunction exhibits excellent hydrogen evolution activity comparable to commercial 20% Pt / C across the entire pH range (overpotential 14 mV in 1 M KOH, Tafel slope 20 mV dec). -1 The overpotential in 0.5 M H₂SO₄ is 43 mV, and the Tafel slope is 43 mV dec. -1 ; Overpotential 22 mV, Tafel slope 41 mV dec in 1 M PBS -1 ).

[0037] like Figure 6 As shown, the stability of the catalyst was evaluated using the chronoamperometry method. At a constant potential (based on a current density of 30 mA cm⁻¹ in the LSV curve), the catalyst was tested. -2 The potential values ​​corresponding to the time were measured, and the current decay over time in 1 M KOH, 0.5 M H2SO4, and 1 M PBS solutions was tested. The results showed that in 1 M KOH, the current decay of the CuO / PdO@Pd-C heterojunction over time was measured at 30 mAcm⁻¹. -2 It can operate stably for up to 250 hours at a given current density; up to 1175 hours in 0.5 M H2SO4; and up to 350 hours in 1 M PBS. These results demonstrate that this heterojunction material exhibits excellent electrochemical stability across the entire pH range, and its superior hydrogen evolution performance and stability suggest its potential to replace commercial Pt / C.

[0038] like Figure 7 As shown, the industrial application prospects of the catalyst in simulated seawater (1 M KOH + 0.5 M NaCl) were further evaluated. Its stability at industrial-grade current densities was tested using the chronoamperometry method. The results show that the electrode can reach 500 mA cm⁻¹ with only an input potential of -1.37 V. -2The current density was maintained at a high level, and the device operated stably for 700 hours under these conditions without significant degradation. This excellent stability fully demonstrates the promising industrial application prospects of CuO / PdO@Pd-C heterojunctions in seawater hydrogen production.

[0039] like Figure 8 As shown, to better reflect practical applications, the hydrogen evolution performance of the catalyst in real natural seawater (taken from the South China Sea) was tested. The natural seawater, after simple filtration to remove sediment and silt, was used to prepare a 1 M KOH seawater solution (5.61 g KOH dissolved in 100 mL of seawater, the supernatant was collected after standing, pH 13.8). The LSV test method was consistent with the alkaline solution conditions. The results showed that in alkaline seawater (1 M KOH + seawater), the CuO / PdO@Pd-C heterojunction exhibited good hydrogen evolution performance at 10 mA cm⁻¹. -2 The overpotential at the current density was 26.7 mV, slightly higher than the 25 mV in simulated seawater. This is likely due to the influence of impurities such as calcium and magnesium ions and microorganisms present in natural seawater. Nevertheless, this result fully validates the reliability of the simulated seawater conditions. Meanwhile, at an industrial-grade current density (500 mA cm⁻¹), [further details are needed to complete the translation]. -2 Under these conditions, the catalyst can achieve efficient hydrogen production in natural seawater with an overpotential of only 272 mV, demonstrating its great potential for application in complex real seawater environments.

[0040] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structures made using the contents of the present invention specification and drawings, whether directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of the present invention.

Claims

1. A CuO / PdO@Pd-C heterojunction nanomaterial, characterized in that, The heterojunction nanomaterial was prepared by a solvothermal method using PdCl2·xH2O, CuCl2·2H2O, and anhydrous phloroglucinol as raw materials.

2. The preparation method of CuO / PdO@Pd-C heterojunction nanomaterial according to claim 1, characterized in that, PdCl2·xH2O, CuCl2·2H2O, anhydrous phloroglucinol, octadecene, and oleylamine were uniformly mixed and reacted using a one-pot solvothermal method. After the reaction was completed, the heterojunction nanomaterial was obtained by washing and separation.

3. The preparation method according to claim 2, characterized in that, The molar ratio of PdCl2·xH2O, CuCl2·2H2O, and anhydrous phloroglucinol is 2:0.5:0.

1.

4. The preparation method according to claim 2, characterized in that, The solvent used in the reaction is oleylamine and octadecene.

5. The preparation method according to claim 2, characterized in that, The reaction conditions were a reaction temperature of 210 °C and a reaction time of 5 h.

6. The preparation method according to claim 5, characterized in that, The temperature was programmed to 210 °C, specifically heated to 210 °C at a rate of 1 °C min -1 -1.

7. The preparation method according to claim 2, characterized in that, After the reaction is completed, the mixture of equal volumes of cyclohexane and anhydrous ethanol is used for washing to remove unreacted impurities and surface-adsorbed organic matter.

8. The application of the CuO / PdO@Pd-C heterojunction nanomaterial as described in claim 1 as a catalyst in hydrogen production by water electrolysis.

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