Preparation method of CoPx-CeO2 loaded platinum catalyst with core-shell structure and application of CoPx-CeO2 loaded platinum catalyst in seawater electrolysis for hydrogen production

Abstract

The invention belongs to the technical field of hydrolysis hydrogen production, and particularly relates to a preparation method of a CoPx-CeO2 loaded platinum catalyst with a core-shell structure and application of the CoPx-CeO2 loaded platinum catalyst in seawater electrolysis hydrogen production. A Co (CO3) 0.5 (OH) nanorod precursor is prepared on foamed nickel through a hydrothermal method and then calcined to obtain CoPx, a CeO2 film is electrically deposited to obtain a CoPx-CeO2 composite carrier, and platinum is impregnated and loaded to obtain the CoPx-CeO2-Pt catalyst. The catalyst shows excellent hydrogen evolution catalytic activity in seawater, and the CoPx-CeO2 composite carrier prevents Pt nano-particles from being agglomerated through interaction of metal carriers, so that the atom utilization rate of Pt is increased. Meanwhile, the CeO2 film actively enriches OH <-> in an alkaline electrolyte to construct a local high-alkalinity microenvironment on the surface of the catalyst, Cl <-> in seawater is prevented from getting close to an active site corroding the catalyst through electrostatic repulsion, and the stability and durability of the catalyst are improved.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis hydrogen production technology, specifically relating to a core-shell structured CoP. x Preparation method of @CeO2 supported platinum catalyst and its application in seawater electrolysis for hydrogen production. Background Technology

[0002] The depletion of traditional fossil fuels and the severe environmental problems they bring are driving the global energy system towards a cleaner and more sustainable future. Hydrogen energy, due to its high energy density (142 MJ / kg⁻¹), is a promising option. -1 With its characteristics of high purity and zero carbon emissions, water electrolysis is considered one of the most promising sustainable clean energy sources of the 21st century. Unlike traditional fossil fuel hydrogen production processes such as coal gasification and natural gas reforming, which are accompanied by large amounts of greenhouse gas emissions, water electrolysis hydrogen production technology is a promising and sustainable green hydrogen production route due to its high product purity and ability to achieve zero carbon emissions.

[0003] However, traditional freshwater electrolysis for hydrogen production faces challenges such as uneven water resource distribution and high desalination costs. Directly utilizing abundant seawater (accounting for approximately 96.5% of global water resources) as the electrolyte promises to significantly reduce hydrogen production costs and geographical limitations. Compared to proton exchange membrane electrolysis and solid oxide electrolysis, alkaline seawater electrolysis has become a research hotspot due to its relatively mature technology and low cost. However, seawater has a complex composition, especially its high concentration of chloride ions (Cl-). - During electrolysis, not only does the electrolyte corrode electrode materials, but it also poisons the active sites of the hydrogen evolution reaction (HER) catalyst, leading to a sharp decline in activity and stability. Therefore, developing HER catalysts suitable for alkaline seawater environments, possessing high activity, high stability, and excellent resistance to chloride ion poisoning, is key to achieving a breakthrough in seawater electrolysis hydrogen production technology. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a core-shell structured CoP x Preparation method of @CeO2 supported platinum catalyst and its application in seawater electrolysis for hydrogen production. The core-shell structure CoP x @CeO2 composite carrier with CoP x With a core and a CeO2 shell, the strong interaction between the metal and the carrier promotes the uniform dispersion of Pt nanoparticles, thereby improving the utilization rate and mass activity of the noble metal under low Pt loading. Simultaneously, this CeO2 shell can actively enrich OH- in alkaline electrolytes. - A locally highly alkaline microenvironment is constructed on the catalyst surface; this microenvironment can effectively block and repel Cl from seawater through electrostatic repulsion. - The proximity to and corrosion of the catalyst's active sites gives the catalyst excellent chemical stability and durability in chlorine-containing media.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a core-shell structured CoP x A method for preparing a CeO2-supported platinum catalyst, the method comprising the following steps: (1) Co(NO3)2·6H2O, NH4F, and CO(NH2)2 were dissolved in ultrapure water to form a mixed solution. Pretreated nickel foam was then added to the solution and subjected to a hydrothermal reaction. After cooling to room temperature, the solution was washed and dried to obtain Co(CO3). 0.5 (OH) / NF; (2) Co(CO3) 0.5 CoP was obtained by phosphating (OH) / NF with NaH2PO2 as the phosphorus source under an argon atmosphere. x / NF; (3) CoP x / NF was electrodeposited to obtain CoP in a three-electrode system. x @CeO2 / NF; (4) The original chloroplatinic acid solution was diluted with ultrapure water to obtain a diluted chloroplatinic acid solution. CoP x @CeO2 / NF was impregnated in a diluted chloroplatinic acid solution, washed, and dried to obtain CoP. x @CeO2-Pt catalyst.

[0006] Further, in step (1), the molar ratio of Co(NO3)2·6H2O, NH4F, and CO(NH2)2 is 1~2:5.5~6.5:2~3, and the volume ratio of Co(NO3)2·6H2O to ultrapure water is 1~2 mmol:35~45 mL.

[0007] Furthermore, in step (1), the temperature of the hydrothermal reaction is 110~130 ℃ and the reaction time is 4~8 h.

[0008] Further, in step (1), the pretreatment method is as follows: first, place the nickel foam in hydrochloric acid solution for ultrasonic cleaning, then place it in acetone for ultrasonic cleaning, and finally clean it with ethanol and ultrapure water respectively. After vacuum drying, the pretreated nickel foam is obtained.

[0009] Furthermore, the concentration of the hydrochloric acid solution is 1~2 mol / L, the ultrasonic cleaning time is 10~30 min, and the ethanol and ultrapure water are used for cleaning 2~3 times each.

[0010] Further, in step (1), the washing and drying refers to washing with pure water and ethanol 3-4 times, and finally placing it in a vacuum drying oven to dry overnight.

[0011] Further, in step (2), the ratio of the amount of phosphorus source NaH2PO2 to Co(NO3)2·6H2O in step (1) is 0.5~1.5 g:1~2 mmol, and the phosphating process is specifically as follows: under an argon atmosphere, the temperature is raised to 250~450 ℃ at a heating rate of 2~5 ℃ / min and held for 1~2 h.

[0012] Further, in step (3), the electrodeposition operation specifically involves using CoP... x A three-electrode system was constructed, consisting of a working electrode ( / NF), a Pt sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. Constant potential deposition was performed in 2.0–2.5 mM Ce(NO3)3·6H2O and 8.0–10.0 mM NaCl solutions, with a deposition potential of 0.5–0.6 V (vs. Ag / AgCl) and a deposition time of 10–30 min.

[0013] Further, in step (4), the concentration of the original chloroplatinic acid solution is 0.1~0.2 g / mL, and the volume ratio of the original chloroplatinic acid solution to the diluted chloroplatinic acid solution is 3~7:500~1000.

[0014] Further, in step (4), the soaking time is 1-2 h, and then the sample is washed 3-4 times with ultrapure water and vacuum dried.

[0015] A second aspect of the present invention provides a core-shell structured CoP prepared by the above-described preparation method. x @CeO2 supported platinum catalyst.

[0016] A third aspect of the present invention provides a core-shell structure CoP as described above. x Application of @CeO2 supported platinum catalyst in seawater electrolysis for hydrogen production.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention prepares a core-shell structured CoP by impregnation method. x @CeO2 supported platinum catalyst (CoP) x @CeO2-Pt), that is, first preparing the nanorod-shaped precursor Co(CO3) on nickel foam via hydrothermal treatment. 0.5 (OH) was then calcined under an argon atmosphere to obtain CoP. x Then, amorphous CeO2 is deposited onto CoP by electrodeposition. x Surface, forming CoP x CoP with a core and a CeO2 shell x @CeO2 composite carrier, and finally Pt nanoparticles were spontaneously reduced to CoP by impregnation method.x CoP was obtained on a CeO2 composite support. x @CeO2-Pt catalyst. This method of spontaneously reducing Pt through impregnation is simple, requires no additional reducing agents such as NaBH4, and is very environmentally friendly. At the same time, the slow kinetics of the spontaneous reduction process are conducive to the uniform dispersion of Pt nanoparticles, thereby improving the utilization rate of the precious metal Pt.

[0018] (2) The core-shell structure CoP prepared in this invention x @CeO2 supported platinum catalyst due to CoP x The strong metal-support interaction between the CeO2 composite support and Pt nanoparticles optimizes the electron density of active sites, significantly increasing the electrochemical active surface area of ​​the catalyst to expose more active sites, thus enabling it to exhibit excellent hydrogen evolution performance in alkaline seawater. Simultaneously, the amorphous shell of CeO2 not only promotes water dissociation but also actively enriches OH groups. - A locally highly alkaline microenvironment is constructed on the catalyst surface, utilizing OH... - With Cl - The electrostatic repulsion between them prevents Cl in seawater from - They migrate from the bulk solution to the catalyst surface and corrode the active sites of the catalyst. Attached Figure Description

[0019] Figure 1 For CoP x Transmission electron microscopy characterization of @CeO2-Pt / NF.

[0020] Figure 2 For CoP x Comparison of X-ray electron diffraction patterns of @CeO2-Pt / NF and standard card.

[0021] Figure 3 For CoP x Linear sweep voltammetry curve of hydrogen evolution in @CeO2-Pt / NF in alkaline simulated seawater electrolyte.

[0022] Figure 4 For CoP x @CeO2-Pt / NF was tested in an alkaline simulated seawater electrolyte at 100 mA cm⁻¹ using a chronopotential method. -2 The stability plot was obtained at the given current density.

[0023] Figure 5 For CoP x In-situ Raman spectra of @CeO2-Pt / NF.

[0024] Figure 6 For CoP xIn-situ infrared spectrum of @CeO2-Pt / NF. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0027] Example 1: Core-shell structure CoP x Preparation and characterization of @CeO2 supported platinum catalyst (1) Dissolve 0.48 g Co(NO3)2·6H2O, 0.36 g CO(NH2)2 and 0.093 g NH4F in 40 mL of ultrapure water. After stirring for 30 min, transfer the solution to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene and place the pretreated nickel foam (first ultrasonically clean the nickel foam in 1.5 mol / L hydrochloric acid solution for 20 min, then ultrasonically clean it in acetone for 20 min, and finally wash it three times with ethanol and water respectively, and then vacuum dry it.) Heat the nickel foam at 120 ℃ for 6 h, cool it to room temperature, take out the sample, wash it four times with pure water and ethanol, and then vacuum dry it overnight to obtain Co(CO3). 0.5 (OH) / NF.

[0028] (2) Mix 1.0 g of NaH2PO2 and Co(CO3) 0.5 (OH) / NF was placed in a tube furnace, with NaH2PO2 located upstream. Under an argon atmosphere, the temperature was increased to 350 °C at a rate of 5 °C / min and held for 2 h to obtain CoP. x / NF.

[0029] (3) CoP x Using / NF as the working electrode, a Pt sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode, constant potential deposition was performed in a solution containing 2 mM Ce(NO3)3·6H2O and 10 mM NaCl. The deposition potential was 0.5 V (vs. Ag / AgCl), and the deposition time was 10 min. After washing four times with pure water, CoP was obtained by vacuum drying. x @CeO2 / NF.

[0030] (4) Take 50 μL of 0.1 g / mL chloroplatinic acid hexahydrate solution, dilute it with ultrapure water to 5 mL to obtain the diluted impregnation solution, and then apply CoP... x @CeO2 / NF was immersed in it for 1 hour, then the sample was removed, washed four times with ultrapure water, and then vacuum dried to obtain CoP. x @CeO2-Pt / NF.

[0031] The prepared CoP x @CeO2-Pt / NF was characterized using a transmission electron microscope (TEM) on a FEI Talos F200S instrument (USA). Figure 1 Figure a shows the morphology at a magnification of 50 nm, where the prepared CoP can be observed. x @CeO2-Pt is a nanorod structure. Figure 1 Figure b shows the morphology at a magnification of 10 nm, where Pt nanoparticles can be observed to be uniformly dispersed on the surface of the nanorods. Figure 1 As shown in Figure c, at a magnification of 5 nm, an amorphous CeO2 film can be seen on the outer side of the nanorod. Figure 1 d, e, and f are respectively Figure 1 In region c, regions d, e, and f have lattice fringes corresponding to the CoP (111) crystal plane, the Co2P (120) crystal plane, and the (200) crystal plane of Pt nanoparticles, respectively. Furthermore, for CoP... x X-ray electron diffraction tests were performed on @CeO2-Pt / NF using a Rigaku Ultima IV instrument. Figure 2 As shown, CoP x The results corresponded well with the CoP and Co2P standard cards, but no peaks for CeO2 and Pt were observed. This is mainly because CeO2 is an amorphous structure, and X-ray electron diffraction can only observe the crystalline structure. The low Pt content resulted in the absence of a noticeable Pt peak.

[0032] Comparative Example 1: Preparation of Commercial Pt / C 5 mg of 20 wt% commercial platinum-carbon powder was dissolved in 1 mL of a solution containing 880 μL isopropanol, 100 μL of pure water, and 20 μL of Nafion. The solution was sonicated for at least 30 min to ensure uniform dispersion of the platinum-carbon powder, thus obtaining commercial platinum-carbon ink. 135 μL of the commercial platinum-carbon ink was dropped onto a clean nickel foam measuring 1 × 1 cm and dried in an oven.

[0033] Comparative Example 2: CoP x Preparation of -Pt (1) Dissolve 0.48 g Co(NO3)2·6H2O, 0.36 g CO(NH2)2 and 0.093 g NH4F in 40 mL of ultrapure water. After stirring for 30 min, transfer the solution to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene and place the pretreated nickel foam (first ultrasonically clean the nickel foam in 1.5 mol / L hydrochloric acid solution for 20 min, then ultrasonically clean it in acetone for 20 min, and finally wash it three times with ethanol and water respectively, and then vacuum dry it.) Heat the nickel foam at 120 ℃ for 6 h, cool it to room temperature, take out the sample, wash it four times with pure water and ethanol, and then vacuum dry it overnight to obtain Co(CO3). 0.5 (OH) / NF.

[0034] (2) Mix 1.0 g of NaH2PO2 and Co(CO3) 0.5 (OH) / NF was placed in a tube furnace, with NaH2PO2 located upstream. Under an argon atmosphere, the temperature was increased to 350 °C at a rate of 5 °C / min and held for 2 h to obtain CoP. x / NF.

[0035] (3) Take 50 μL of 0.1 g / mL chloroplatinic acid hexahydrate solution, dilute it with ultrapure water to 5 mL to obtain the diluted impregnation solution, and then apply CoP... x / NF was immersed in it for 1 h, then the sample was removed, washed 4 times with ultrapure water and vacuum dried for 1 h. Then, under a 5% H2 / Ar mixed atmosphere, the temperature was increased to 200 °C at a heating rate of 2 °C / min and held for 2 h to obtain CoP. x -Pt / NF.

[0036] Comparative Example 3: Preparation of CeO2-Pt (1) Using NF as the working electrode, Pt sheet as the counter electrode, and saturated Ag / AgCl electrode as the reference electrode, constant potential deposition was carried out in a solution containing 2 mM Ce(NO3)3·6H2O and 10 mM NaCl. The deposition potential was 0.5 V (vs. Ag / AgCl) and the deposition time was 10 min. After washing with pure water 4 times, CeO2 / NF was obtained by vacuum drying.

[0037] (2) Take 50 μL of 0.1 g / mL chloroplatinic acid hexahydrate solution, dilute it with ultrapure water to 5 mL to obtain the diluted impregnation solution, immerse CeO2 / NF in it, take out the sample after soaking for 1 h, wash it with ultrapure water 4 times, and then vacuum dry to obtain CeO2-Pt / NF.

[0038] Test Example 1: Electrochemical Test Electrochemical testing employed a three-electrode system. The testing instrument was an AUTOLAB (model AUT88171). The electrolyte was alkaline simulated seawater (1 M KOH + 3.5 wt% NaCl). Hg / HgO was used as the reference electrode, a carbon rod as the counter electrode, and the working electrode was the CoP prepared in Example 1. x @CeO2-Pt / NF catalyst. After verifying the circuit connection, set the program to use Linearsweep voltammetry potentiostatic for hydrogen evolution testing. The potential range was set to -0.75 to -1.8V, and the scan rate was 0.005 V / s. A linear sweep voltammetry (LSV) curve was then plotted.

[0039] Figure 3 Demonstrated CoP x The linear sweep voltammetric curve of hydrogen evolution of @CeO2-Pt / NF in alkaline simulated seawater (1 M KOH + 3.5 wt% NaCl) is shown in the figure. As can be seen from the figure, CoP... x @CeO2-Pt / NF exhibits good hydrogen evolution performance in alkaline simulated seawater, driving 10 mA cm⁻¹ -2 The current density required is only 19 mV overpotential, which is significantly better than CoP. x -Pt / NF, CeO2-Pt / NF and commercial Pt / C.

[0040] Figure 4 Demonstrated CoP x The stability of @CeO2-Pt / NF in alkaline simulated seawater (1 M KOH + 3.5 wt% NaCl) was obtained by chronovoltammetry. As shown in the figure, CoP... x @CeO2-Pt / NF catalyst can achieve 100 mA cm⁻¹ -2 It operates stably for 200 hours at a current density, while CoP x -Pt / NF voltage over 24 hours compared to CoP x @CeO2-Pt / NF exhibits a certain degree of voltage decay, while commercial Pt / C and CeO2-Pt / NF show significant voltage decay within 24 hours, proving that CoP x @CeO2-Pt / NF exhibits excellent stability in alkaline seawater.

[0041] Figure 5 Demonstrated CoP x The results of in-situ Raman spectroscopy of @CeO2-Pt / NF were obtained using a Horiba LabRAM HR Evolution instrument. As shown in the figure, the in-situ HER test was performed in a CO2-saturated 0.5 M KHCO3 solution (pH=7.26), located at 10¹² cm⁻¹.-1 and 1064cm -1 The peaks at each location are attributed to HCO3. - and CO3 2- As the voltage gradually increases, CoP x CO3 in @CeO2-Pt sample 2- The corresponding signal peaks gradually increase, leading to HCO3 - / CO3 2- The intensity ratio decreased significantly. This change directly confirms that in the alkaline HER process, the presence of the CeO2 layer on the catalyst surface induces a stronger local alkaline microenvironment. The accumulation of negative charges on the catalyst surface caused by this microenvironment can repel Cl in the bulk solution. - Migrating poisons the active sites of catalysts.

[0042] Figure 6 Demonstrated CoP x The results of in-situ infrared spectroscopy measurements of @CeO2-Pt / NF were obtained using a Shimadzu IRXross FTIR Spectrophotometer. As shown in the figure, with the gradual increase of the operating voltage, CoP... x @CeO2-Pt / NF can promote the dissociation of water and effectively prevent Cl-. - Poisoning the active site of the catalyst, causing CoP x @CeO2-Pt exhibits excellent catalytic activity and stability.

[0043] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A core-shell structure CoP x The method for preparing a CeO2-supported platinum catalyst is characterized by, The preparation method includes the following steps: (1) Co(NO3)2·6H2O, NH4F, and CO(NH2)2 were dissolved in ultrapure water to form a mixed solution. Pretreated nickel foam was then added to the solution and subjected to a hydrothermal reaction. After cooling to room temperature, the solution was washed and dried to obtain Co(CO3). 0.5 (OH) / NF; (2) Co(CO3) 0.5 CoP was obtained by phosphating (OH) / NF with NaH2PO2 as the phosphorus source under an argon atmosphere. x / NF; (3) CoP x / NF was electrodeposited to obtain CoP in a three-electrode system. x @CeO2 / NF; (4) The original chloroplatinic acid solution was diluted with ultrapure water to obtain a diluted chloroplatinic acid solution. CoP x @CeO2 / NF was impregnated in a diluted chloroplatinic acid solution, washed, and dried to obtain CoP. x @CeO2-Pt catalyst.

2. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (1), the molar ratio of Co(NO3)2·6H2O, NH4F, and CO(NH2)2 is 1~2:5.5~6.5:2~3, and the volume ratio of Co(NO3)2·6H2O to ultrapure water is 1~2 mmol:35~45 mL.

3. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (1), the temperature of the hydrothermal reaction is 110~130 ℃ and the reaction time is 4~8 h.

4. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (1), the pretreatment method is as follows: first, place the nickel foam in hydrochloric acid solution for ultrasonic cleaning, then place it in acetone for ultrasonic cleaning, and finally clean it with ethanol and ultrapure water respectively. After vacuum drying, the pretreated nickel foam is obtained.

5. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (2), the ratio of the amount of phosphorus source NaH2PO2 to Co(NO3)2·6H2O in step (1) is 0.5~1.5 g:1~2 mmol. The phosphating process is as follows: under an argon atmosphere, the temperature is raised to 250~450℃ at a heating rate of 2~5℃ / min and held for 1~2 h.

6. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (3), the electrodeposition operation specifically involves using CoP... x A three-electrode system was constructed, consisting of a working electrode ( / NF), a Pt sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. Constant potential deposition was performed in 2.0–2.5 mM Ce(NO3)3·6H2O and 8.0–10.0 mM NaCl solutions, with a deposition potential of 0.5–0.6 V and a deposition time of 10–30 min.

7. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (4), the concentration of the original chloroplatinic acid solution is 0.1~0.2 g / mL, and the volume ratio of the original chloroplatinic acid solution to the diluted chloroplatinic acid solution is 3~7:500~1000.

8. A core-shell structure CoP according to claim 1 x The method for preparing a CeO2-supported platinum catalyst is characterized by, In step (4), the soaking time is 1 to 2 hours.

9. A core-shell structured CoP prepared by the preparation method according to any one of claims 1 to 8 x @CeO2 supported platinum catalyst.

10. A core-shell structure CoP as described in claim 9 x Application of @CeO2 supported platinum catalyst in seawater electrolysis for hydrogen production.

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