An oxygen evolution reaction catalyst for electrolysis of seawater and a preparation method and application thereof

Abstract

The application discloses a core-shell structure of an oxygen evolution reaction catalyst cerium dioxide coated on a nickel-iron hydrotalcite and a preparation method and application thereof. The CeO2@NiFe-LDH / NF non-noble metal nano core-shell structure electrocatalyst is prepared on a nickel foam through a two-step method of hydrothermal and electrodeposition. In the heterogeneous structure catalyst, the NiFe-LDH is a nanosheet, and the CeO2 is a dense film connected by tiny nanoparticles and covers on the LDH nanosheet. In the alkaline simulated seawater and alkaline natural seawater electrolyte, the oxygen evolution performance of the CeO2@NiFe-LDH / NF is obviously superior to that of the NiFe-LDH / NF without the covering layer. The main reason is that the introduced CeO2 provides oxygen vacancies for the catalytic interface and the heterogeneous interface formed with the NiFe-LDH, and the catalyst oxygen evolution activity is improved; in addition, the deposited CeO2 layer can effectively inhibit the Cl ‑ corrosion to the catalyst. Therefore, the CeO2@NiFe-LDH / NF exhibits excellent OER catalytic activity and stability in the electrolyte containing chloride ions.

Description

Technical field:

[0001] The present invention belongs to the field of new energy material technology and electrochemical catalysis, and specifically relates to an oxygen evolution catalyst for electrolysis of seawater, comprising cerium oxide nanoparticles coated with nickel-iron hydrotalcite nanosheets; it also relates to a method for preparing the catalyst and its electrocatalytic application in oxygen evolution reactions in electrolysis of seawater. Background technology:

[0002] The oxygen evolution reaction (OER) is a key electrode process in seawater electrolysis, but the abundant chloride ions (~0.5 mol / L) in seawater present significant challenges. Under acidic conditions, the equilibrium potential of the OER relative to the standard hydrogen electrode is only 130 mV higher than that of the chlorine evolution reaction (CER). However, the two-electron transfer CER exhibits a kinetic advantage over the four-electron transfer CER. Under alkaline conditions (pH > 7.5), chloride ions compete with the OER for electrons and are oxidized to hypochlorite ions. However, the onset potential of this reaction is 490 mV higher than that of the OER, necessitating the use of highly efficient catalysts to achieve selective oxygen evolution from seawater at overpotentials far below those required for hypochlorite formation. Even in alkaline media, the large amount of aggressive chloride ions in seawater can severely corrode the catalyst, reducing its catalytic activity. To prevent activity decay, the catalyst must exhibit a certain degree of resistance to chloride ion corrosion. Currently, the noble metal electrode materials IrO2 and RuO2 exhibit the best OER activity under alkaline conditions, but their scarcity and poor electrochemical stability limit their widespread application as seawater electrolysis catalysts in energy storage and conversion systems. Therefore, the development of new, efficient, stable, and inexpensive electrocatalysts is crucial. In recent years, compounds such as transition metal sulfides, phosphides, oxides, and hydroxides have attracted widespread attention from researchers due to their abundant reserves, low cost, and long-term durability, providing more possibilities for the selection of seawater electrolysis catalysts.

[0003] Transition metal layered hydroxides (LDHs) have excellent OER electrocatalytic activity due to their special layered structure and compositional tunability, especially NiFe-LDH has been widely used. Cerium (Ce), as the most abundant rare earth metal, has a unique 4f orbital structure [Xe]4f 2 6s 2 , strong affinity for oxygen and good ion / electron conductivity. Its common valence state is Ce 4+ / Ce 3+ The redox process is carried out through the loss of electrons or oxygen, and abundant oxygen vacancies are generated. Its excellent oxygen storage capacity can accelerate the interfacial electron transfer. The electronic interaction between CeO2 and the coupled catalyst can regulate the adsorption and activation energy of the intermediates. Under the action of oxygen vacancies in the OER process, the OH -The adsorption of CeO2 is conducive to the formation of hydroperoxides (*OOH, a key intermediate in OER), promoting the progress of OER. In addition, due to its mechanical stability and excellent corrosion resistance, CeO2 can inhibit the degradation of the main electrocatalyst in electrolytes containing chloride ions. Considering that three-dimensional core-shell structured catalysts can provide a large surface area and abundant active sites in the electrolysis of seawater, there has been no report on the construction of core-shell structured catalysts composed of transition metal layered hydroxides and ceria nanoparticles and their use in catalyzing the electrolysis of oxygen from seawater.

[0004] The present invention utilizes a solvothermal method to synthesize NiFe-LDH on a nickel foam (NF) support. Under optimal electrodeposition conditions, a dense film composed of CeO2 nanoparticles is electrodeposited on the surface of the NiFe-LDH to produce a composite catalyst with a CeO2@NiFe-LDH / NF core-shell structure. The synergistic effect and strong electronic interaction between the NiFe-LDH nanosheets and CeO2 nanoparticles promote electron transfer, enhancing the OER performance of the core-shell heterostructure CeO2@NiFe-LDH. At the same time, CeO2 creates more oxygen vacancies on the catalyst surface, which is beneficial for improving the inherent catalytic activity of the catalyst. The dense film composed of CeO2 nanoparticles improves the catalyst's resistance to chloride ion corrosion, making CeO2@NiFe-LDH more stable during the electrolysis of chloride ion-containing aqueous solutions. This invention has important theoretical significance and potential application value for the development of transition metal OER catalysts for the selective catalytic production of hydrogen and oxygen from seawater. Summary of the invention:

[0005] In response to the deficiencies in the prior art and the needs of research and application in this field, one of the objectives of the present invention is to provide an oxygen evolution reaction catalyst for the electrolysis of seawater; namely, a core-shell structure catalyst formed by depositing cerium dioxide nanoparticles on nickel-iron hydrotalcite nanosheets; prepared by constant current technology under optimal deposition time, current density and electrolyte concentration conditions; the catalyst is in situ grown on nickel foam, denoted as CeO2@NiFe-LDH / NF;.

[0006] A second object of the present invention is to provide a method for preparing an oxygen evolution reaction catalyst for electrolysis of seawater, which specifically comprises the following steps:

[0007] (a) Preparation of NiFe-LDH / NF

[0008] The specification is 3*2cm 2The nickel foam was ultrasonically treated with 3 mol / L hydrochloric acid solution, deionized water and ethanol for 20, 5 and 20 min respectively, and dried at 50°C for 6 h; 1 mmol of Ni(NO3)2·6H2O, 0.5 mmol of Fe(NO3)3·9H2O and 5 mmol of urea were weighed and dissolved in 40 mL of deionized water; the mixed solution was transferred to a 100 mL polytetrafluoroethylene reactor, and a piece of pretreated nickel foam was added, and it was reacted at 120°C for 12 h. After cooling to room temperature, the nickel foam was taken out from the reactor, washed several times with deionized water and anhydrous ethanol, and then dried at 50°C for 5 h to obtain NiFe-LDH / NF;

[0009] (b) Preparation of CeO2@NiFe-LDH / NF

[0010] NiFe-LDH (1*1cm) prepared by (a) 2 ) as the working electrode, platinum wire as the counter electrode, saturated Ag / AgCl as the reference electrode, 50-250 mM Ce(NO3)3·6H2O solution as the electrolyte, at a current density of -1 to -3 mA cm -2 , constant current deposition was carried out under the condition of deposition time of 300 to 2400 s to grow CeO2 on its surface and prepare core-shell CeO2@NiFe-LDH catalyst;

[0011] CeO2 nanoparticles with a particle size of less than 10 nm in the oxygen evolution reaction catalyst for electrolysis of seawater are densely covered on the surface of NiFe-LDH nanosheets. The lateral size of the NiFe-LDH nanosheets is 300 to 500 nm and the thickness is 10 nm.

[0012] A third object of the present invention is to provide an oxygen evolution reaction catalyst for electrolysis of seawater for catalytic application in the anode oxygen evolution reaction of electrolysis of seawater.

[0013] Under optimal deposition conditions, the present invention prepared a CeO2@NiFe-LDH / NF core-shell structure of oxygen evolution reaction catalyst for seawater electrolysis; this heterogeneous core-shell structure promotes electron transfer and produces more oxygen vacancies on the surface, thereby enhancing the catalytic activity of the catalyst and improving its corrosion resistance and stability in chloride ion-containing electrolytes.

[0014] Compared with the prior art, the present invention has the following main advantages and beneficial effects:

[0015] 1) The CeO2@NiFe-LDH / NF catalyst of the present invention is a non-precious metal composite material. The raw materials used are easy to purchase, abundant in resources and low in cost. The experimental method is easy to operate and is convenient for large-scale production.

[0016] 2) The CeO2@NiFe-LDH / NF core-shell structure of the catalyst described in the present invention has good OER catalytic selectivity, corrosion resistance and stability in chloride ion-containing electrolytes, and has obvious advantages over precious metal catalysts. Description of the drawings:

[0017] Figure 1 They are scanning electron microscope images of NiFe-LDH / NF (A) obtained in comparative example 2 and CeO2@NiFe-LDH / NF (B) obtained in example 1, and transmission electron microscope images (CD) of CeO2@NiFe-LDH / NF obtained in example 1.

[0018] Figure 2 These are the XRD patterns of the catalyst NiFe-LDH / NF obtained in Comparative Example 2 and the catalyst CeO2@NiFe-LDH obtained in Example 1.

[0019] Figure 3 OER linear sweep voltammetry curves (a) and Tafel slope (b) of CeO2@NiFe-LDH / NF-1 obtained in Example 1, NF obtained in Comparative Example 1, NiFe-LDH / NF obtained in Comparative Example 2, CeO2@NF obtained in Comparative Example 3, and commercial IrO2-modified NF in 1M KOH+0.5M NaCl.

[0020] Figure 4 Cyclic voltammetry curves of CeO2@NiFe-LDH / NF-1 obtained in Example 1 and NiFe-LDH / NF obtained in Comparative Example 2 in 1M KOH and 1M KOH+0.2M K4[Fe(CN)6], respectively.

[0021] Figure 5 OER linear sweep voltammetry curves (a) and Tafel slope (b) of CeO2@NiFe-LDH / NF-1 obtained in Example 1 and NiFe-LDH / NF obtained in Comparative Example 2 in 1 M KOH, 1 M KOH + 0.5 M NaCl and 1 M KOH + seawater.

[0022] Figure 6 The constant voltage it (a) of the OER of CeO2@NiFe-LDH / NF-1 obtained in Example 1 in 1 M KOH + 0.5 M NaCl, the comparison of the linear voltammetric curves before and after the test (b), and the constant voltage it (c) in 1 M KOH + seawater.

[0023] Figure 7 The constant voltage it of OER of NiFe-LDH / NF obtained in Comparative Example 2 in 1 M KOH (a) and 1 M KOH+0.5 M NaCl (b). Specific implementation method:

[0024] For a further understanding of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited in any way.

[0025] Example 1:

[0026] (a) Preparation of NiFe-LDH / NF

[0027] Take the size 3*2cm 2 The nickel foam was ultrasonically treated with 3 mol / L hydrochloric acid solution, deionized water and ethanol for 20, 5 and 20 min, respectively, and dried at 50°C for 6 h; 0.2908 g Ni(NO3)2·6H2O (1 mmol), 0.202 g Fe(NO3)3·9H2O (0.5 mmol) and 0.303 g urea (5 mmol) were weighed and dissolved in 40 mL of deionized water; the mixed solution was transferred to a 100 mL polytetrafluoroethylene reactor, and a piece of pretreated nickel foam was added, and it was reacted at 120°C for 12 h, cooled to room temperature, and the nickel foam was removed from the reactor, washed several times with deionized water and anhydrous ethanol, respectively, and then dried at 50°C for 5 h to synthesize NiFe-LDH / NF;

[0028] (b) Preparation of CeO2@NiFe-LDH / NF-1

[0029] The NiFe-LDH (1*1cm 2 ) as the working electrode, platinum wire as the counter electrode, and saturated Ag / AgCl as the reference electrode (the internal reference solution is a saturated KCl solution) to form a three-electrode system for deposition. The deposition current density is -2 mA cm -2 The electrolyte is 50 mL of 150 mM Ce(NO3)3·6H2O solution, and the deposition time is 1200 s to obtain the catalyst CeO2@NiFe-LDH / NF-1;

[0030] Example 2:

[0031] (a) Preparation of NiFe-LDH / NF

[0032] Prepared according to the method and conditions of step (a) in Example 1;

[0033] (b) Preparation of CeO2@NiFe-LDH / NF-2

[0034] The NiFe-LDH (1*1cm 2) as the working electrode, platinum wire as the counter electrode, and saturated Ag / AgCl as the reference electrode (the internal reference solution is a saturated KCl solution) to form a three-electrode system for deposition. The deposition current density is -2 mA cm -2 The electrolyte is 50 mL of 150 mM Ce(NO3)3·6H2O solution, and the deposition time is 300 s to obtain the catalyst CeO2@NiFe-LDH / NF-2;

[0035] Example 3:

[0036] (a) Preparation of NiFe-LDH / NF

[0037] Prepared according to the method and conditions of step (a) in Example 1;

[0038] (b) Preparation of CeO2@NiFe-LDH / NF-3

[0039] The NiFe-LDH (1*1cm 2 ) as the working electrode, platinum wire as the counter electrode, and saturated Ag / AgCl as the reference electrode (the internal reference solution is a saturated KCl solution) to form a three-electrode system for deposition. The deposition current density is -2 mA cm -2 The electrolyte is 50 mL of 150 mM Ce(NO3)3·6H2O solution, and the deposition time is 600 s to obtain the catalyst CeO2@NiFe-LDH / NF-3;

[0040] Example 4:

[0041] (a) Preparation of NiFe-LDH / NF

[0042] Prepared according to the method and conditions of step (a) in Example 1;

[0043] (b) Preparation of CeO2@NiFe-LDH / NF-4

[0044] The NiFe-LDH (1*1cm 2 ) as the working electrode, platinum wire as the counter electrode, and saturated Ag / AgCl as the reference electrode (the internal reference solution is a saturated KCl solution) to form a three-electrode system for deposition. The deposition current density is -2 mA cm -2 The electrolyte is 50 mL of 150 mM Ce(NO3)3·6H2O solution, and the deposition time is 1800 s to obtain the catalyst CeO2@NiFe-LDH / NF-4;

[0045] Example 5:

[0046] (a) Preparation of NiFe-LDH / NF

[0047] Prepared according to the method and conditions of step (a) in Example 1 ;

[0048] (b) Preparation of CeO2@NiFe-LDH / NF-5

[0049] The NiFe-LDH prepared in (a) (1*1 cm 2 ) was used as the working electrode, platinum wire as the counter electrode, saturated Ag / AgCl as the reference electrode (internal reference solution was saturated KCl solution) to form a three-electrode system for deposition. The deposition current density was -2 mA cm -2 , the electrolyte was 50 mL of Ce(NO3)3·6H2O solution containing 150 mM, and the deposition time was 2400 s, to obtain the catalyst CeO2@NiFe-LDH / NF-5;

[0050] Example 6:

[0051] (a) Preparation of NiFe-LDH / NF

[0052] Prepared according to the method and conditions of step (a) in Example 1 ;

[0053] (b) Preparation of CeO2@NiFe-LDH / NF-6

[0054] The NiFe-LDH prepared in (a) (1*1 cm 2 ) was used as the working electrode, platinum wire as the counter electrode, saturated Ag / AgCl as the reference electrode (internal reference solution was saturated KCl solution) to form a three-electrode system for deposition. The deposition current density was -1 mA cm -2 , the electrolyte was 50 mL of Ce(NO3)3·6H2O solution containing 150 mM, and the deposition time was 1200 s, to obtain the catalyst CeO2@NiFe-LDH / NF-6;

[0055] Example 7:

[0056] (a) Preparation of NiFe-LDH / NF

[0057] Prepared according to the method and conditions of step (a) in Example 1 ;

[0058] (b) Preparation of CeO2@NiFe-LDH / NF-7

[0059] The NiFe-LDH prepared in (a) (1*1 cm 2 ) was used as the working electrode, platinum wire as the counter electrode, saturated Ag / AgCl as the reference electrode (internal reference solution was saturated KCl solution) to form a three-electrode system for deposition. The deposition current density was -3 mA cm-2 The electrolyte is 50 mL of 150 mM Ce(NO3)3·6H2O solution, and the deposition time is 1200 s to obtain the catalyst CeO2@NiFe-LDH / NF-7;

[0060] Comparative Example 1:

[0061] Preparation of nickel foam

[0062] Cut the nickel foam into 2×3cm pieces 2 , ultrasonically treated with 3 mol / L hydrochloric acid solution, deionized water, and ethanol for 20, 5, and 20 min, respectively, to remove surface oxides and organic molecules, and then dried at 50 °C for 6 h;

[0063] Comparative Example 2:

[0064] Preparation of NiFe-LDH / NF

[0065] Prepared according to the method and conditions of step (a) in Example 1;

[0066] Comparative Example 3:

[0067] Preparation of CeO2@NF

[0068] Take the size 3*2cm 2 Nickel foam was ultrasonically treated with 3 mol / L hydrochloric acid solution, deionized water, and ethanol for 20, 5, and 20 min, respectively, and dried at 50°C for 6 h. Deposition was performed using a three-electrode system consisting of the pretreated nickel foam as the working electrode, platinum wire as the counter electrode, and saturated Ag / AgCl as the reference electrode (the internal reference solution was saturated KCl solution). The deposition current density was -2 mA cm -2 The electrolyte is 50 mL of 150 mM Ce(NO3)3·6H2O solution, and the deposition time is 1200 s to obtain the catalyst CeO2@NF.

[0069] Figure 1The figures are scanning electron micrographs of NiFe-LDH / NF (A) obtained in comparative example 2 and CeO2@NiFe-LDH / NF-1 (B) obtained in example 1, and transmission electron micrographs (CD) of CeO2@NiFe-LDH / NF obtained in example 1, respectively. As can be seen from Figure A, NiFe-LDH / NF presents a flower-like array of nanosheets, which are evenly arranged on the nickel foam and cross-connected with each other. As can be seen from Figure B, the product CeO2@NiFe-LDH / NF-1 after electrodeposition of CeO2 better maintains the NiFe-LDH nanoflower sheet array, and a dense film formed by connecting CeO2 nanoparticles with tiny particle size grows on the nanosheets. Both Figures C and D clearly show the simultaneous existence of sheet structure and particle structure, and the CeO2 particle structure is attached to the NiFe-LDH nanosheet, indicating that the catalyst forms a heterogeneous core-shell structure after CeO2 deposition.

[0070] Figure 2 The XRD patterns of the catalyst NiFe-LDH / NF obtained in Comparative Example 2 and the catalyst CeO2@NiFe-LDH-1 obtained in Example 1 are shown. Due to the presence of the nickel foam substrate, there are two strong diffraction peaks of Ni at 44.5° and 51.9° (JCPDS No.04-0850). The diffraction peaks at 11.5°, 23.2°, 34.5°, 39.0°, 60.2°, and 65.2° correspond to the (003), (006), (012), (015), (110), and (116) crystal planes of NiFe-LDH, respectively (JCPDS No.51-0463). However, due to the dense coating of the CeO2 nanolayer, the diffraction peaks of NiFe-LDH are not obvious. Compared with NiFe-LDH / NF, the diffraction peaks of CeO2@NiFe-LDH / NF-1 at 28.7°, 33.2°, 47.4°, 56.3°, 59.3°, 69.3°, 76.6°, and 79.3° are respectively attributed to the (111), (200), (220), (311), (222), (400), (331), and (420) crystal planes of face-centered cubic CeO2 (JCPDS No. 34-0394). Therefore, it can be inferred that the catalyst CeO2@NiFe-LDH / NF-1 was successfully synthesized.

[0071] The following electrocatalytic performance tests all used a saturated Hg / HgO electrode as the reference electrode, a millstone electrode as the counter electrode, and a scan rate of 2 mV / s.

[0072] Figure 3OER linear sweep voltammetry curves (a) and Tafel slope (b) of CeO2@NiFe-LDH / NF-1 obtained in Example 1, NF obtained in Comparative Example 1, NiFe-LDH / NF obtained in Comparative Example 2, CeO2@NF obtained in Comparative Example 3, and commercial IrO2 modified NF in 1M KOH+0.5M NaCl. As can be seen from the figure, the current density reaches 100mA / cm 2 When the catalyst is heated to 100 ℃ and 100 ℃, the CeO2@NiFe-LDH / NF-1 catalyst has the lowest overpotential and the smallest Tafel slope, indicating that the presence of NiFe-LDH and CeO2 plays a synergistic role in promoting the OER performance of the catalyst. The formation of the heterogeneous structure promotes the transfer of electrons, improves the electronic properties of the catalyst surface, and enhances its catalytic performance in chloride ion-containing electrolytes.

[0073] Figure 4 The cyclic voltammetry curves of CeO2@NiFe-LDH / NF-1 obtained in Example 1 and NiFe-LDH / NF obtained in Comparative Example 2 in 1M KOH and 1M KOH + 0.2M K4[Fe(CN)6], respectively. The solid line is the electrolyte without 0.2M K4Fe(CN)6. From the CV curves of CeO2@NiFe-LDH / NF-1 and NiFe-LDH, it can be found that both have a Ni at 1.41V (vs RHE). 2+ / Ni 3+ In an alkaline solution containing potassium ferrocyanide redox ions, NiFe-LDH exhibits obvious ferrocyanide and ferricyanide oxidation peaks at 1.33V (vs RHE) and 1.41V (vs RHE), respectively. 2+ / Ni 3+ The redox peak of CeO2@NiFe-LDH / NF-1 is Ni 2+ / Ni 3+ The redox peak, but the peak current is significantly reduced, and the Fe in ferrocyanide 2+ / Fe 3+ The redox peak is significantly lower than that of NiFe-LDH, indicating that the negatively charged CeO2 layer has a strong effect on the [Fe(CN)6] 3- / 4- It has an electrostatic repulsion effect, which effectively hinders the diffusion of these redox ions from the electrolyte to the catalyst, avoids their poisoning of the catalyst during anode polarization, and ensures the integrity of the OER active center.

[0074] Figure 5Linear sweep voltammetry curves (a) and Tafel slope plots (b) of Ce02@NiFe-LDH / NF-1 obtained from Example 1 and NiFe-LDH / NF obtained from Comparative Example 2 in 1 M KOH, 1 M KOH + 0.5 M NaCl and 1 M KOH + seawater. It is observed that the LSV curves of Ce02@NiFe-LDH / NF-1 in 1 M KOH + 0.5 M NaCl and 1 M KOH electrolytes almost overlap, indicating that the OER catalytic performance of the catalyst in the two electrolytes is close, which means that the catalyst undergoes the same OER reaction through the same kinetic mechanism in the two electrolytes, that is, Ce02@NiFe-LDH / NF-1 has good selectivity for oxygen evolution catalytic performance in the electrolyte containing chloride ions. However, the OER performance of NiFe-LDH in 1 M KOH + 0.5 M NaCl and 1 M KOH electrolytes is quite different, confirming that the deposition of Ce02 not only synergizes with NiFe-LDH to increase the activity of the catalyst, but also effectively alleviates the Cl - Corrosion effect on the catalyst to ensure the selective oxygen evolution catalytic performance, corrosion resistance and stability of Ce02@NiFe-LDH in the chloride ion-containing electrolyte. In 1 M KOH + seawater electrolyte, it is observed that the catalytic performance of Ce02@NiFe-LDH / NF-1 has a slight attenuation compared to the other two electrolytes, while NiFe-LDH shows a significant attenuation. This indicates that the presence of Ce02 improves the OER selectivity and stability of the catalyst in seawater, and on the other hand, it also indicates that the dust, colloids and bacteria or metal cations present in natural seawater react with the alkaline electrolyte to form insoluble precipitates (Ca(OH)2 / Mg(OH)2) which will poison the catalyst, reduce the catalytic activity and long-term stability.

[0075] Figure 6 Linear sweep voltammetry curves (a) and Tafel slope plots (b) of Ce02@NiFe-LDH / NF-1 obtained from Example 1 and NiFe-LDH / NF obtained from Comparative Example 2 in 1 M KOH, 1 M KOH + 0.5 M NaCl and 1 M KOH + seawater. It is observed that the LSV curves of Ce02@NiFe-LDH / NF-1 in 1 M KOH + 0.5 M NaCl and 1 M KOH electrolytes almost overlap, indicating that the OER catalytic performance of the catalyst in the two electrolytes is close, which means that the catalyst undergoes the same OER reaction through the same kinetic mechanism in the two electrolytes, that is, Ce02@NiFe-LDH / NF-1 has good selectivity for oxygen evolution catalytic performance in the electrolyte containing chloride ions. However, the OER performance of NiFe-LDH in 1 M KOH + 0.5 M NaCl and 1 M KOH electrolytes is quite different, confirming that the deposition of Ce02 not only synergizes with NiFe-LDH to increase the activity of the catalyst, but also effectively alleviates the Cl

[0076] Figure 7The constant voltages of NiFe-LDH / NF in 1M KOH (a) and 1M KOH+0.5M NaCl (b) obtained in Comparative Example 2 are shown. After 30 h of fixed potential testing, the initial current in 1M KOH+0.5M NaCl significantly decayed compared to that in 1M KOH solution, which may be due to the presence of Cl. - This result once again confirms that the electrodeposited CeO2 layer not only cooperates with NiFe-LDH to enhance the catalyst performance, but also protects CeO2@NiFe-LDH / NF from Cl - It can reduce the corrosion of catalyst and improve its resistance to chloride ion corrosion.

Claims

1. A method for preparing an oxygen evolution reaction catalyst for electrolysis of alkaline seawater, characterized in that The catalyst is a core-shell structure formed by cerium dioxide nanoparticles deposited on nickel-iron hydrotalcite nanosheets; the catalyst is in situ grown on nickel foam, denoted as CeO2@NiFe-LDH / NF; The method for preparing the oxygen evolution reaction catalyst for electrolysis of alkaline seawater comprises the following specific steps: (a) Preparation of NiFe-LDH / NF The size is 3*2 cm 2 The nickel foam was ultrasonically treated with 3 mol / L hydrochloric acid solution, deionized water, and ethanol for 20, 5, and 20 min, respectively, and dried at 50°C for 6 h. 1 mmol of Ni(NO3)2·6H2O, 0.5 mmol of Fe(NO3)3·9H2O, and 5 mmol of urea were weighed and dissolved in 40 mL of deionized water. The mixed solution was transferred to a 100 mL polytetrafluoroethylene reactor, and a piece of pretreated nickel foam was added. The mixture was reacted at 120°C for 12 h. After cooling to room temperature, the nickel foam was removed from the reactor, washed several times with deionized water and anhydrous ethanol, and then dried at 50°C for 5 h to obtain NiFe-LDH / NF. (b) Preparation of CeO2@NiFe-LDH / NF The size of the product prepared in step (a) is 1*1 cm 2 NiFe-LDH was used as the working electrode, platinum wire as the counter electrode, saturated Ag / AgCl as the reference electrode, and Ce(NO3)3·6H2O solution with a concentration of 50~250 mM was used as the electrolyte. The current density was -1 ~ -3 mA cm -2 CeO2 was grown on the surface of the catalyst by constant current deposition at a deposition time of 300 to 2400 s to prepare a core-shell CeO2@NiFe-LDH catalyst. CeO2 nanoparticles with a particle size of less than 10 nm in the oxygen evolution reaction catalyst for electrolysis of alkaline seawater are densely covered on the surface of NiFe-LDH nanosheets, and the lateral size of the NiFe-LDH nanosheets is 300-500 nm and the thickness is 10 nm; The oxygen evolution reaction catalyst for electrolysis of alkaline seawater is used for catalytic application of anode oxygen evolution reaction in electrolysis of alkaline seawater.

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