Preparation method and application of urea electrooxidation catalyst in seawater

Abstract

The invention belongs to the technical field of urea electrooxidation catalysis in seawater, and discloses a preparation method and application of a urea electrooxidation catalyst in seawater, and the preparation method comprises the following steps: S1, preparing soaking foam nickel, and drying for later use; s2, adding an aqueous solution containing chromium nitrate nonahydrate and cobalt potassium cyanide into the foamed nickel, cleaning and drying after the reaction is completed, and generating NiCo-PBA (at) NF; wherein the concentration of the chromium nitrate nonahydrate is 0.75 mg / ml to 1.25 mg / ml, and the concentration of the cobalt potassium cyanide is 0.75 mg / ml to 1.25 mg / ml; adding the CrNiCo-PBA (at) NF into an aqueous solution containing thiourea, cleaning and drying after the reaction is completed, and generating S-CrNiCo-PBA (at) NF; wherein the concentration of the thiourea ranges from 0.15 mmol / ml to 0.4 mmol / ml; according to the method, through two times of hydrothermal treatment, the S-CrNiCo-PBA-coated NF grows on the foamed nickel in situ to serve as the electrocatalyst, meanwhile, the chlorine evolution reaction is effectively inhibited through urea oxidation, and the UOR electrocatalytic efficiency and stability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of urea electro-oxidation catalysis in seawater, and in particular to a preparation method and application of a urea electro-oxidation catalyst in seawater. Background Art

[0002] Hydrogen (H2) has broad application prospects in replacing fossil fuels as a sustainable and clean energy source. Water electrolysis accompanied by oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is an effective way to obtain hydrogen. However, the slow OER kinetics limits the overall energy conversion. To further alleviate this problem, electrooxidation of other small molecules including methanol, ethanol, hydrazine and urea is considered to be a promising alternative method. Among them, urea oxidation (UOR), which has a theoretical voltage (0.37 V) lower than the OER thermodynamic potential (1.23 V), is an attractive method. However, due to the complex six-electron transfer reaction, electrocatalysts are required to accelerate the anodic UOR process.

[0003] However, noble metal-based electrocatalysts such as Pt / C, IrO2, and RuO2 have been widely considered to be highly efficient but expensive electrocatalytic reactions. Therefore, there is an urgent need to develop a low-cost, high-efficiency, and highly stable electrocatalyst that can improve the adsorption rate of reaction intermediates and reduce energy loss. Summary of the Invention

[0004] The present invention aims to provide a preparation method and application of a urea electro-oxidation catalyst in seawater. Through two hydrothermal treatments, S-CrNiCo-PBA@NF is in situ grown on nickel foam as an electrocatalyst. At the same time, urea oxidation is used to effectively inhibit the chlorine evolution reaction, thereby improving the UOR electrocatalytic efficiency and stability.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a urea electrooxidation catalyst in seawater comprises the following steps:

[0007] S1. Material pretreatment:

[0008] The nickel foam was soaked in HCl, washed with ethanol and deionized water for several times, and vacuum dried for later use;

[0009] S2. Preparation of CrNiCo-PBA@NF:

[0010] The nickel foam treated in step S1 is placed in a reaction vessel, and an aqueous solution containing chromium nitrate nonahydrate and potassium cobalt cyanide is added. The mixture is reacted at 80°C to 120°C for 2.5 hours to 4 hours. After the reaction is completed, the mixture is washed with deionized water and ethanol and dried in vacuo to produce NiCo-PBA@NF; wherein the concentration of chromium nitrate nonahydrate is 0.75 mg / ml to 1.25 mg / ml, and the concentration of potassium cobalt cyanide is 0.75 mg / ml to 1.25 mg / ml;

[0011] Preparation of S3 and S-CrNiCo-PBA@NF:

[0012] The CrNiCo-PBA@NF obtained in step S2 is placed in a reaction vessel, an aqueous solution containing thiourea is added, and the reaction is carried out at 180°C to 220°C for 0.5h to 1.5h. After the reaction is completed, it is cleaned with deionized water and ethanol and vacuum dried to generate a urea electro-oxidation catalyst S-CrNiCo-PBA@NF; wherein the concentration of thiourea is 0.15mmol / ml to 0.4mmol / ml.

[0013] Furthermore, in S1, the size of the nickel foam is 1×3 cm 2 , soak in 3M HCl for 30 min.

[0014] Furthermore, in S2, the concentration of chromium nitrate nonahydrate is 1 mg / ml, and the concentration of potassium cobalt cyanide is 1 mg / ml.

[0015] Furthermore, in S2, the reaction at 80°C to 120°C for 2.5 hours to 4 hours includes: reacting at 100°C for 3 hours.

[0016] Furthermore, in S3, the concentration of thiourea is 0.2 mmol / ml.

[0017] Furthermore, in S3, the reacting at 180°C to 220°C for 0.5h to 1.5h includes reacting at 200°C for 1h.

[0018] Furthermore, in S2 and S3, the volume ratio of the aqueous solution containing chromium nitrate nonahydrate and potassium cobalt cyanide to the aqueous solution containing thiourea is 1:1.

[0019] The catalyst prepared by the above-mentioned method for preparing a urea electrooxidation catalyst in seawater is used in seawater electrolysis.

[0020] The beneficial effects of the technical solution are:

[0021] The present invention provides a method for preparing a urea electrooxidation catalyst in seawater. The raw materials used are easily available and low in cost. The S-CrNiCo-PBA@NF prepared by hydrothermal and sulfurization treatment exhibits good UOR catalytic performance in simulated seawater. -2 The overpotential is 1.36 V at 200 mA cm -2 Under the condition of 1.49V, the overpotential is lower than that of the simple seawater electrolysis. 2 , continuously tested for 90 h. S-CrNiCo-PBA@NF exhibited good UOR catalytic performance and good stability in simulated seawater, providing new ideas for the practical application of seawater electrolysis in the future.

[0022] Specifically, the electrode material S-CrNiCo-PBA@NF grows uniformly on the surface of nickel foam, and forms a granular structure composed of interconnected thin sheets. These granular structures are regularly and evenly distributed on the nickel foam skeleton. This compact and interconnected granular structure not only helps the electrode material S-CrNiCo-PBA@NF fully expose the active sites, but also promotes mass transfer and gas diffusion during the reaction, thereby significantly improving the activity of UOR. At a current density of 100 mA / cm 2 When the overpotential of S-CrNiCo-PBA@NF reaches 1.36 V, the 2 When the overpotential reaches 1.50 V, which is lower than that of the nickel foam after single Co doping and Cr doping, indicating that the co-doping of Co and Cr can effectively improve the catalytic performance, and the Cl in the electrolyte - Ions promote electrocatalysis; the Tafel slope of S-CrNiCo-PBA@NF is lower than that of S-CrNi@NF (110 mV dec -1 ) and S-NiCo-PBA@NF (115mV dec -1 ), which also proves the superior electrocatalytic performance of S-CrNiCo-PBA@NF for UOR; S-CrNiCo-PBA@NF has the lowest impedance, which is conducive to electron transfer, thereby accelerating the electrochemical reaction. In addition to the excellent electrocatalytic performance, the present invention evaluated the electrochemical stability of the electrocatalyst through the IT curve test. S-CrNiCo-PBA@NF has the best electrocatalytic performance at an initial current density of 50mA / cm 2 , continuous testing for 90h, with excellent stability performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The XRD spectra, XPS spectra, SEM images and TEM images of different materials in Example 2 of the present invention are shown;

[0024] In the figure, a is the XRD spectrum of CrNiCo-PBA@NF, S-CrNiCo-PBA@NF, NiCo@NF, S-NiCo-PBA@NF, CrNi@NF, and S-CrNi@NF; b is the XPS spectrum Co 2p of S-CrNiCo-PBA@NF, c is the XPS spectrum Ni 2p of S-CrNiCo-PBA@NF, d is the XPS spectrum Cr 2p of S-CrNiCo-PBA@NF, and e is the XPS spectrum of S-CrNiCo-PBA@NF. Figure 2 p; fh are SEM images of S-CrNiCo-PBA@NF at different magnifications; i is the Ni element distribution map corresponding to the TEM image of S-CrNiCo-PBA@NF, j is the Co element distribution map corresponding to the TEM image of S-CrNiCo-PBA@NF, k is the Cr element distribution map corresponding to the TEM image of S-CrNiCo-PBA@NF, l is the S element distribution map corresponding to the TEM image of S-CrNiCo-PBA@NF;

[0025] Figure 2 1 is an LSV polarization curve diagram of different materials in Example 2 of the present invention;

[0026] In the figure, a is the LSV polarization curve of S-Ni@NF, S-CrNi@NF, S-NiCo-PBA@NF, and S-CrNiCo-PBA@NF; b is the LSV polarization curve of different samples at a current density of 100 mA / cm 2 and 200mA / cm 2 c is the overpotential bar graph of different samples; c is the Tafel slope curve of different samples; d is the LSV polarization curve of CrNiCo-PBA@NF at different temperatures; e is the LSV polarization curve of CrNiCo-PBA@NF at different hydrothermal times; f is the LSV polarization curve of CrNiCo-PBA@NF at different Co and Cr doping ratios; g is the LSV polarization curve of S-CrNiCo-PBA@NF at different sulfurization times; h is the LSV polarization curve of S-CrNiCo-PBA@NF at different sulfurization temperatures; i is the LSV polarization curve of S-CrNiCo-PBA@NF in different electrolytes;

[0027] Figure 3 CV curves of different materials at different scanning speeds in Example 3;

[0028] In the figure, a is the CV curve of S-Ni@NF at different scanning speeds, b is the CV curve of S-NiCo-PBA@NF at different scanning speeds, c is the CV curve of S-CrNi@NF at different scanning speeds, and d is the CV curve of S-CrNiCo-PBA@NF at different scanning rates;

[0029] Figure 4 CV curves of different materials in Example 3, C dl graph, it curve and EIS curve;

[0030] Figure a is the CV curve of S-CrNiCo-PBA@NF at different scan rates; b is the C of different samples dl Figure 2c shows the S-CrNiCo-PBA@NF at an initial current density of 50 mA cm -2 d is the EIS curve. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0032] Hydrogen (H2) has broad application prospects in replacing fossil fuels as a sustainable and clean energy source. Water electrolysis accompanied by oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is an effective way to obtain hydrogen. However, the slow OER kinetics limits the overall energy conversion. To further alleviate this problem, electrooxidation of other small molecules including methanol, ethanol, hydrazine and urea is considered to be a promising alternative method. Among them, urea oxidation (UOR), which has a theoretical voltage (0.37 V) lower than the OER thermodynamic potential (1.23 V), is an attractive method. However, due to the complex six-electron transfer reaction, electrocatalysts are required to accelerate the anodic UOR process.

[0033] However, noble metal-based electrocatalysts such as Pt / C, IrO2 and RuO2 have been widely regarded as efficient but expensive electrocatalytic reactions. In recent years, nickel-based catalysts such as phosphides, oxides, sulfides and hydroxides have been effectively used in electrocatalysis. Among them, nickel sulfide and nickel phosphide have broad application prospects in HER and UOR due to their rich active sites, adjustable structure and good intrinsic activity. The present invention uses two hydrothermal treatments to in situ grow S-CrNiCo-PBA@NF on nickel foam as an electrocatalyst, and at the same time uses urea oxidation to effectively inhibit the chlorine evolution reaction and improve the UOR electrocatalytic efficiency. The catalyst has a current density of 100mA cm in 1M KOH+0.5M NaCl+0.33M urea electrolyte.-2 The overpotential is 1.36 V at 200 mA cm -2 Under the condition of overpotential of 1.49V, and the current density of 50mA / cm 2 , continuously tested for 90h, with good stability, providing new ideas for the practical application of seawater electrolysis in the future.

[0034] Example 1

[0035] A method for preparing a urea electrooxidation catalyst in seawater and its application, comprising the following steps:

[0036] S1. Material pretreatment:

[0037] Press nickel foam (NF) into 1×3cm 2 The size was determined by soaking in 3 M HCl for 30 min, washing three times with ethanol and deionized water, and drying in vacuum.

[0038] S2. Preparation of CrNiCo-PBA@NF:

[0039] The nickel foam (NF) prepared in step S1 was placed in a high-temperature reactor, and 20 ml of an aqueous solution containing 20 mg of chromium nitrate nonahydrate and 20 mg of potassium cobalt cyanide was added. The reactor was covered with a stainless steel jacket and placed in a forced air drying oven for reaction at 100°C for 3 h. After the reactor was cooled naturally, the reactor was taken out, cleaned with deionized water and ethanol, and vacuum dried to produce NiCo-PBA@NF material.

[0040] To optimize the experimental conditions, the reaction time and temperature were fixed, and the catalyst performance was investigated at different concentrations of chromium nitrate nonahydrate and potassium cobalt cyanide (0.75 mg / ml to 1.25 mg / ml). The resulting products were designated mCr,nCoNi@NF (m = 15 mg, 20 mg, 25 mg; n = 15 mg, 20 mg, 25 mg). The catalyst with the best OER performance (i.e., m = 20 mg, n = 20 mg, i.e., chromium nitrate nonahydrate and potassium cobalt cyanide concentrations of 1 mg / ml) was selected and the temperature and time were investigated separately. The resulting products were designated Cr,Co(x,y)Ni@NF (x = 80°C, 100°C, 120°C; y = 2.5 h, 3 h, 4 h). The optimal temperature and time were x = 100°C, y = 3 h.

[0041] Preparation of S3 and S-CrNiCo-PBA@NF:

[0042] The CrNiCo-PBA@NF obtained in step S2 was placed in a high-temperature reactor, and 20 ml of an aqueous solution containing 4 mmol of thiourea was added. The reactor was covered with a stainless steel jacket and placed in a forced air drying oven for reaction at 200°C for 1 hour. After the reactor was cooled naturally, the reactor was taken out, cleaned with deionized water and ethanol, and vacuum dried to produce S-CrNiCo-PBA@NF material.

[0043] To optimize the experimental conditions, the reaction time and temperature were fixed, and the catalyst performance was investigated at different thiourea concentrations (0.15 mmol / ml to 0.4 mmol / ml). The products obtained were denoted as rS-CrNiCo-PBA@NF (r = 3 mmol, 4 mmol, 5 mmol, 6 mmol, and 8 mmol). The product with the best OER performance (r = 4 mmol, i.e., thiourea concentration of 0.2 mmol / ml) was selected and the temperature and time were investigated separately. The products obtained were denoted as (p, q)S-CrNiCo-PBA@NF (p = 180°C, 200°C, and 220°C; q = 0.5 h, 1.0 h, and 1.5 h). The optimal temperature and time were p = 200°C and q = 1 h.

[0044] Example 2

[0045] The urea electrooxidation catalyst S-CrNiCo-PBA@NF prepared in Example 1 was subjected to electrochemical testing and XRD, XPS, SEM and TEM detection. The test process and test results are shown below:

[0046] XRD, XPS, SEM and TEM test results Figure 1 As shown, Figure 1 (a) XRD spectra of CrNiCo-PBA@NF, S-CrNiCo-PBA@NF, NiCo-PBA@NF, S-NiCo-PBA@NF, CrNi@NF, and SCrNi@NF. Comparison with standard charts demonstrates the successful synthesis of the catalysts of this invention. The surface elements and chemical valence states of the electrode material S-CrNiCo-PBA@NF were characterized using X-ray photoelectron spectroscopy (XPS). Figure 1 b to Figure 1 e shows the fitting peak spectra of Co 2p, Ni 2p, Cr 2p and S2p orbitals respectively. Figure 1 b and Figure 1 c It can be concluded that the high-resolution XPS spectra of Co 2p and Ni 2p are fitted to 2p 3 / 2 and 2p 1 / 2 Two spin orbits. Figure 1 The two peaks at 780.5 eV and 795.7 eV in b belong to Co 2+, the two peaks at 774.4eV and 789.5eV belong to Co 3+ , indicating that the Co element is Co 2+ / Co 3+ There are two oxidation states. Figure 1 In c, the two peaks at 854.9 eV and 872.5 eV are attributed to Ni 2+ , and the two peaks at 859.9eV and 877.3eV are attributed to Ni 3+ .exist Figure 1 In d, the Cr 2p spectrum at 587.2 eV and 577.3 eV corresponds to the Cr 2p 1 / 2 and Cr 2p 3 / 2 , indicating that Cr in the composite material exists in trivalent form. Figure 1 It can be concluded that the peaks at 161.5eV and 162.1eV belong to S2p 1 / 2 and S2p 3 / 2 , confirmed that S 2- The results show that the product contains Cr, Co, Ni, and S elements, and the main element is Cr 3+ 、Co 2+ / Co 3+ 、Ni 2+ / Ni 3+ and S 2- oxidation state exists.

[0047] Scanning electron microscopy (SEM) was used to characterize the morphology and microstructure of the electrode material S-CrNiCo-PBA@NF. Figure 1 fh are SEM images of the electrode material at different magnifications when the catalyst is S-CrNiCo-PBA@NF. Figure 1 It can be concluded that the surface of the electrode material S-CrNiCo-PBA@NF is rough and grows evenly on the surface of nickel foam. Figure 1 As shown in Figures 1f, 1g, and 1h, granular structures formed by interconnected thin sheets can be observed. These granular structures are regularly and evenly distributed on the nickel foam skeleton. This tight and interconnected granular structure not only helps the electrode material S-CrNiCo-PBA@NF to fully expose the active sites, but also promotes mass transfer and gas diffusion during the reaction, thereby significantly improving the activity of UOR. Figure 1 il is the TEM image of S-CrNiCo-PBA@NF catalyst material, in which the uniform distribution of Ni, Co, Cr, and S elements can be seen, which further confirms that the catalyst elements are uniformly and dispersedly loaded on the nickel foam substrate.

[0048] The OER electrocatalytic performance of all samples was studied using a three-electrode system in a simulated seawater (1 M KOH + 0.5 M NaCl) + 0.33 M urea electrolyte on a CHI630e instrument. S-CrNiCo-PBA@NF was used as the working electrode, a graphite rod as the counter electrode, and saturated Hg / HgO as the reference electrode. All potentials were calculated according to the Nernst equation: E(RHE) = E(Hg / HgO) + 0.0591 pH + 0.098. OER linear sweep voltammetry (LSV) analysis was performed at a scan rate of 5 mV s. -1 All samples were activated by 20 cycles of cyclic voltammetry (CV) before testing. The samples were activated by increasing the scan rate (20, 40, 60, 80, 100 and 120 mV s) within the appropriate potential in the non-Faraday region. -1 ) to obtain the CV curve for determining the electrochemical double layer capacitance (C dl The stability test was conducted by measuring the current versus time chronoamperometric response (IT curve) in an electrolyte solution containing simulated seawater and 0.33M urea at a current density of 50 mA / cm 2 , continuous testing for 90h.

[0049] Specifically, in order to evaluate the effects of Cr atoms, Co atoms and S atoms on the performance of the catalyst of the present invention, we conducted electrochemical tests. In order to understand the effect of nickel-based catalysts on UOR, we directly sulfurized the treated nickel foam and conducted LSV electrochemical tests. The test results are as follows: Figures 2 to 4 As shown, from Figure 2 a It can be seen that the direct sulfurization performance of the nickel-based substrate is general, so the influence of the nickel-based base on the catalytic activity of the sample can be ignored. Figure 2 As shown in Figures 2a and 2b, the linear sweep voltammetry (LSV) curves after compensation correction show that at a current density of 100 mA / cm 2 When the overpotential of S-CrNiCo-PBA@NF reaches 1.36V, the overpotential of S-CrNiCo-PBA@NF reaches 1.36V at 200mA / cm 2 When the overpotential reaches 1.50 V, it is lower than that of the nickel foam after single Co doping and Cr doping, indicating that the co-doping of Co and Cr can effectively improve the catalytic performance.

[0050] At the same time, by Figure 2 c shows that S-CrNiCo-PBA@NF (107mV dec -1 ) has a lower Tafel slope than S-CrNi@NF (110mV dec -1 ) and S-NiCo-PBA@NF (115mV dec -1 ), which also proves the superior electrocatalytic performance of S-CrNiCo-PBA@NF for UOR. Figure 2In Fig. 1, by comparing S-CrNiCo-PBA@NF in 1MKOH+0.5MNaCl and in 1MKOH+0.5MNaCl+0.33Murea, it can be seen that S-CrNiCo-PBA@NF shows better performance in UOR than OER. At the same time, by comparing S-CrNiCo-PBA@NF in 1M KOH+0.5MNaCl+0.33Murea and in 1MKOH+0.33Murea, it can be seen that Cl in the electrolyte - Ions promote electrocatalysis.

[0051] pass Figure 3 It can be seen that the activation sites on the surface of S-CrNiCo-PBA@NF are more than those of other comparison samples, and Figure 3 Comparing b and 3d, it can be seen that Cr 3+ Ions have a promoting effect on the formation of NiCo-PBA. Figure 4 b It can be clearly seen that the C dl (9.18mF cm -2 ) than S-NiCo-PBA@NF (2.45mF cm -2 )、S-CrNi@NF(1.36mFcm -2 ), which is consistent with the previous speculation that doping Co and Cr provides more active sites for the catalytic reaction. Figure 4 d is the EIS spectrum of different samples. The diameter of the semicircle of the curve in the spectrum is related to the charge transfer resistance R ct The smaller the diameter, the smaller the R ct The smaller it is. Figure 4 d It can be seen that the impedance of S-CrNiCo-PBA@NF is the smallest, which is conducive to electron transfer, thereby accelerating the electrochemical reaction. In addition to excellent electrocatalytic performance, the electrochemical stability of the catalyst is also the key to measuring whether it can be truly applied on a large scale. The present invention evaluates the electrochemical stability of the electrocatalyst through the IT curve test. Since urea is consumed during the test, the electrolyte is replaced midway to maintain the performance of the catalyst. Figure 4 c It can be seen that S-CrNiCo-PBA@NF has an initial current density of 50 mA / cm 2 , continuously tested for 90h, with excellent stability, providing new ideas for the preparation of corrosion-resistant seawater electrolysis catalysts.

[0052] In summary, the present invention provides a method for preparing a urea electrooxidation catalyst in seawater. The raw materials used are easy to obtain and the cost is low. The S-CrNiCo-PBA@NF prepared by hydrothermal and sulfurization treatments exhibits good UOR catalytic performance in simulated seawater. -2 The overpotential is 1.36 V at 200 mA cm -2 Under the condition of 1.49V, the overpotential is lower than that of the simple seawater electrolysis. 2 , continuously tested for 90 h. S-CrNiCo-PBA@NF exhibited good UOR catalytic performance and good stability in simulated seawater, providing new ideas for the practical application of seawater electrolysis in the future.

[0053] The above is only an embodiment of the present invention, and common knowledge such as the specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A method for preparing a urea electrooxidation catalyst in seawater, characterized in that: The following steps are involved: S1. Material pretreatment: The nickel foam was soaked in HCl, washed with ethanol and deionized water for several times, and vacuum dried for later use; S2. Preparation of CrNiCo-PBA@NF: The nickel foam treated in step S1 is placed in a reaction vessel, and an aqueous solution containing chromium nitrate nonahydrate and potassium cobalt cyanide is added. The mixture is reacted at 80°C to 120°C for 2.5 hours to 4 hours. After the reaction is completed, the mixture is washed with deionized water and ethanol and dried in vacuo to produce NiCo-PBA@NF; wherein the concentration of chromium nitrate nonahydrate is 0.75 mg / ml to 1.25 mg / ml, and the concentration of potassium cobalt cyanide is 0.75 mg / ml to 1.25 mg / ml; Preparation of S3 and S-CrNiCo-PBA@NF: The CrNiCo-PBA@NF obtained in step S2 is placed in a reaction vessel, an aqueous solution containing thiourea is added, and the reaction is carried out at 180°C to 220°C for 0.5h to 1.5h. After the reaction is completed, it is cleaned with deionized water and ethanol and vacuum dried to generate a urea electro-oxidation catalyst S-CrNiCo-PBA@NF; wherein the concentration of thiourea is 0.15mmol / ml to 0.4mmol / ml.

2. The method for preparing a urea electro-oxidation catalyst in seawater according to claim 1, characterized in that: In S1, the size of nickel foam is 1×3 cm 2 , soak in 3M HCl for 30 min.

3. The method for preparing a urea electro-oxidation catalyst in seawater according to claim 1, characterized in that: In S2, the concentration of chromium nitrate nonahydrate was 1 mg / ml, and the concentration of potassium cobalt cyanide was 1 mg / ml.

4. The method for preparing a urea electro-oxidation catalyst in seawater according to claim 1, wherein: In S2, the reaction at 80°C to 120°C for 2.5 hours to 4 hours includes: reacting at 100°C for 3 hours.

5. The method for preparing a urea electro-oxidation catalyst in seawater according to claim 1, characterized in that: In S3, the concentration of thiourea was 0.2 mmol / ml.

6. The method for preparing a urea electro-oxidation catalyst in seawater according to claim 1, characterized in that: In S3, the reaction at 180°C to 220°C for 0.5h to 1.5h includes: reacting at 200°C for 1h.

7. The method for preparing a urea electro-oxidation catalyst in seawater according to claim 1, characterized in that: In S2 and S3, the volume ratio of the aqueous solution containing chromium nitrate nonahydrate and potassium cobalt cyanide to the aqueous solution containing thiourea is 1:

1.

8. Use of a catalyst prepared by the method for preparing a urea electrooxidation catalyst in seawater according to any one of claims 1 to 7, characterized in that: It is used in seawater electrolysis.

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