Lanthanide metal oxide modified nickel-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a lanthanide metal oxide modified nickel-based catalyst as well as a preparation method and application thereof, and belongs to the technical field of electrocatalyst preparation. The preparation method comprises the following steps: preparing a Ni-MOF-74 catalyst precursor introduced with lanthanide metal ions through a solvothermal method, and calcining the precursor in a reducing atmosphere to obtain the lanthanide metal oxide modified nickel-based catalyst. The electron transfer of the catalyst at the interface is beneficial to optimizing the binding energy of an intermediate, the alkaline hydroxide activity is greatly improved, meanwhile, the catalyst has great economic benefits, and the catalyst variety is widened.

Description

Technical Field

[0001] The invention relates to the technical field of electrocatalyst preparation, and in particular to a preparation method and application of a lanthanide metal oxide modified nickel-based catalyst. Background Art

[0002] Hydrogen energy has become a powerful alternative to fossil fuels due to its high energy density and pollution-free combustion products, effectively alleviating the global energy and environmental crisis. Hydrogen-oxygen fuel cells are a promising zero-carbon emission energy conversion device with broad application prospects. Although proton exchange membrane fuel cells (PEMFCs) are currently the most advanced fuel cell technology, their cathode oxygen reduction reaction (ORR) requires expensive platinum (Pt)-based catalysts as catalytic materials. With the development of alkaline exchange membranes and the fact that the cathode ORR of alkaline exchange membrane fuel cells (AEMFCs) can achieve performance comparable to that of Pt using inexpensive and abundant transition metal-based materials, researchers have turned their attention to AEMFCs. However, when the electrolyte changes from acidic to alkaline, even the most advanced Pt-based catalysts will reduce the kinetics of the anodic hydrogen oxidation reaction (HOR) by two to three orders of magnitude, which limits the commercial development of AEMFCs. Therefore, the development of efficient and inexpensive non-platinum group metal catalytic materials is of great significance for further reducing the application cost of hydrogen energy and promoting the development of hydrogen energy technology.

[0003] Metal-organic framework (MOF) materials formed by the coordination of metal centers and organic ligands have the advantages of large specific surface area, large pore volume, adjustable pore size, ultra-low mass density, and good stability, and are widely used in the field of electrocatalysis. Due to the controllable selection of different metal centers and organic ligands, MOF materials have been widely synthesized. However, when MOF is used as an electrocatalyst, due to the presence of typical organic linkers around the redox active sites, MOF usually exhibits poor conductivity, making it an insulating material. In addition, the electronic interaction between the metal nodes and the organic linkers further affects the conductivity of MOF. Although simple MOF-based catalysts have a large price advantage, their catalytic activity is still far from that of ideal catalysts. Carbon-based catalysts have shown excellent catalytic activity, chemical stability, cost-effectiveness, and environmental compatibility in research applications. In recent years, significant progress has been made in the synthesis strategy and electrocatalytic activity of MOF-derived carbon-based electrocatalysts. Compared with traditional porous materials, MOF-derived carbon-based porous materials generally exhibit a series of unique advantages, with higher stability than their precursor MOFs, retaining characteristics such as high surface area, structural diversity, and rich porosity. Therefore, MOF-derived catalysts not only have good conductivity and stability, but also successfully maintain porosity while inheriting the large surface area of ​​the MOF precursor. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a lanthanide metal oxide modified nickel-based catalyst, a preparation method and use thereof. The obtained catalyst introduces lanthanide metal ions / clusters into MOF materials, which can effectively improve the catalytic performance of Ni-based MOF materials and has higher HOR performance.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention provides a method for preparing a lanthanide metal oxide modified nickel-based catalyst, comprising the following steps: preparing a Ni-MOF-74 catalyst precursor introduced with lanthanide metal ions by a solvothermal method, and then calcining the precursor in a reducing atmosphere to obtain a lanthanide metal oxide modified nickel-based catalyst.

[0006] Optionally, the lanthanide metal is selected from Ce, Nd or Sm, preferably Sm.

[0007] Optionally, the solvothermal method for preparing the Ni-MOF-74 catalyst precursor introduced with lanthanide metal ions comprises the following steps: dissolving different proportions of lanthanide metal salts, nickel salts and 2,5-dihydroxyterephthalic acid in a mixed solvent, and heating the mixture at 100-200 °C for 12-36 h. After naturally cooling to room temperature, centrifugation and washing, and vacuum drying at 20-80 °C. Preferably, heating the mixture at 120 °C for 24 h, centrifuging with ethanol at a speed of 9000 rpm, and vacuum drying at 60 °C.

[0008] Furthermore, the molar ratio of the lanthanide element to the nickel element in the lanthanide metal salt and the nickel salt is 1:(5-15); preferably 1:10; the molar amount of 2,5-dihydroxyterephthalic acid is 3.0-3.4 times the sum of the molar amounts of the lanthanide element and the nickel element, preferably 3.2 times; the mixed solvent is a mixed solvent composed of DMF, anhydrous ethanol and deionized water, and the volume ratio of DMF, anhydrous ethanol and deionized water is 30:(1.6-2.0):(1.6-2.0); preferably 30:1.8:1.8, and the total molar amount is 3000-6000 times the molar amount of the lanthanide element, preferably 4000 times; the lanthanide metal salt is selected from chloride, acetylacetonate, acetate or nitrate, preferably chloride; the nickel salt is selected from nickel nitrate hexahydrate, nickel chloride or nickel acetylacetonate; preferably nickel nitrate hexahydrate.

[0009] Optionally, the reducing atmosphere includes: a pure nitrogen reducing atmosphere, a pure argon reducing atmosphere, a hydrogen / nitrogen mixed reducing atmosphere or a hydrogen / argon mixed reducing atmosphere, preferably a hydrogen / nitrogen mixed reducing atmosphere; further, the volume ratio of nitrogen to hydrogen is 50:1, 40:1, 30:1, 20:1, 10:1, preferably 20:1.

[0010] Optionally, the calcination treatment in a reducing atmosphere is: calcination treatment is performed in a reducing atmosphere using a tubular furnace, and the calcination treatment conditions are calcination at 400-600° C. for 30-120 min, preferably calcination at 500° C. for 60 min.

[0011] In order to achieve the above-mentioned object of the invention, the present invention provides a lanthanide metal oxide-modified nickel-based catalyst prepared by the above-mentioned preparation method of the lanthanide metal oxide-modified nickel-based catalyst.

[0012] Optionally, the lanthanide metal oxide modified nickel-based catalyst is Ni-CeO x / C、Ni-NdO x / C or Ni-SmO x / C electrocatalyst, preferably Ni-SmO x / C electrocatalyst.

[0013] In order to achieve the above-mentioned purpose of the invention, the present invention applies the lanthanide metal oxide modified nickel-based catalyst to alkaline hydrogen oxidation reaction, and uses it as a MOF derivative electrocatalyst for alkaline hydrogen oxidation reaction.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method of the lanthanide metal oxide modified nickel-based catalyst provided by the present invention uses non-precious metal materials to prepare efficient alkaline HOR catalysts, which reduces production costs, is suitable for commercial mass production, and broadens the types of catalysts.

[0015] 2. The electron transfer at the interface of the lanthanide metal oxide-modified nickel-based catalyst provided by the present invention is conducive to optimizing the binding energy of the intermediate, providing more adsorption sites and active centers for the HOR intermediate, greatly improving the alkaline HOR activity, and has great application prospects.

[0016] 3. Catalyst Ni-SmO x / C In alkaline HOR, the exchange current density normalized to the metal mass ( j 0,m ) is 15.49 mA mg -1 , the exchange current density normalized to the electrochemical specific surface area ( j 0,s ) is 0.045 mA cm -2 , far exceeding the comparison sample Ni / C, and has excellent catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1a is the X-ray diffraction curve of the catalyst precursors NiSm-MOF-74, NiCe-MOF-74, and NiNd-MOF-74 prepared in Examples 1-3 of the present invention. Figure 1 b is the catalyst Ni-SmO prepared in Example 1-3 of the present invention x / C、Ni-CeO x / C、Ni-NdO x X-ray diffraction curve of / C.

[0018] Figure 2 The catalyst Ni-SmO prepared in Example 1 of the present invention x / C (2b) and scanning electron microscopy images of catalyst precursor NiSm-MOF-74 (2a).

[0019] Figure 3 Scanning electron microscope images of the catalyst Ni / C (3b) and the catalyst precursor Ni-MOF-74 (3a) prepared in Comparative Example 1 of the present invention.

[0020] Figure 4 The catalyst Ni-CeO prepared in Example 2 of the present invention x / C (4b) and scanning electron microscopy images of catalyst precursor NiCe-MOF-74 (4a).

[0021] Figure 5 The catalyst Ni-NdO prepared in Example 3 of the present invention x / C (5b) and scanning electron microscopy images of catalyst precursor NiNd-MOF-74 (5a).

[0022] Figure 6 The catalyst Ni-SmO prepared in Example 1 of the present invention x Transmission electron microscopy image and particle size distribution of / C.

[0023] Figure 7 The transmission electron microscope image and particle size distribution diagram of the catalyst Ni / C prepared in Comparative Example 1 of the present invention.

[0024] Figure 8 The catalyst Ni-CeO prepared in Example 2 of the present invention x Transmission electron microscopy image and particle size distribution of / C.

[0025] Fig. 9 The catalyst Ni-NdO prepared in Example 3 of the present invention x Transmission electron microscopy image and particle size distribution of / C.

[0026] Fig.10 a is the catalyst Ni-SmO prepared in Example 1 of the present invention xX-ray photoelectron spectra of Ni 2p of catalyst Ni / C prepared in Example 1. Fig.10 b is the catalyst Ni-SmO prepared in Example 1 of the present invention x X-ray photoelectron spectrum of Sm 3d of / C.

[0027] Fig.11 The samples of Examples 1-3 and Comparative Example 1 were saturated with hydrogen in 0.1 M KOH at a scan rate of 5 mV s -1 , HOR polarization curve at a rotation speed of 2500 rpm.

[0028] Fig.12 a is Ni-SmO prepared in Example 1 of the present invention x Polarization curves of / C catalyst in 0.1 M KOH saturated hydrogen solution at a scan rate of 10 mV s -1 , speed is 2500 to 625 rpm; Fig.12 b is Fig.12 a Koutecky–Levich plot obtained at an overpotential of 12 mV.

[0029] Fig.13 The linear curves are drawn by simplified Butler-Volmer fitting in a small polarization range for the catalysts prepared in Examples 1 to 3 of the present invention and the catalyst prepared in Comparative Example 1.

[0030] Fig.14 Tafel plots of the catalysts prepared in Examples 1 to 3 of the present invention and Comparative Example 1 were drawn using Butler-Volmer fitting.

[0031] Fig.15 CV curves of Examples 1-3 and Comparative Example 1 in nitrogen-saturated 0.1 M KOH, with a scan rate of 50 mV s -1 .

[0032] Fig.16 Preparation of Ni-SmO with different ratios of lanthanide metal salt and nickel salt in Example 1 of the present invention x Polarization curves of / C catalyst in 0.1 M KOH saturated hydrogen solution. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] The invention provides a method for preparing a lanthanide metal oxide modified nickel-based catalyst, comprising the following steps: preparing a Ni-MOF-74 catalyst precursor into which lanthanide metal ions are introduced by a solvent thermal method, and then calcining the precursor in a reducing atmosphere to obtain a lanthanide metal oxide modified nickel-based catalyst.

[0035] The lanthanide metal is selected from Ce, Nd or Sm, preferably Sm.

[0036] The solvothermal method for preparing the Ni-MOF-74 catalyst precursor introduced with lanthanide metal ions comprises the following steps: dissolving lanthanide metal salt, nickel salt and 2,5-dihydroxyterephthalic acid in a mixed solvent, heating and reacting at 100-200°C for 12-36 hours. After naturally cooling to room temperature, centrifugation and washing, and vacuum drying at 20-80°C. Preferably, heating and reacting at 120°C for 24 hours, centrifuging with ethanol at a speed of 9000 rpm, and vacuum drying at 60°C. The raw materials are lanthanide metal salts, nickel salts and 2,5-dihydroxyterephthalic acid in different proportions; for example, 1.31 mmol lanthanide metal salts, 0.13 mmol nickel salts and 0.45 mmol 2,5-dihydroxyterephthalic acid, and the molar ratio of lanthanide metal salts to nickel salts is 1:10; further, the mixed solvent is a mixed solvent composed of DMF, anhydrous ethanol and deionized water in different proportions; for example, a mixed solvent composed of 30 mL DMF, 1.8 mL anhydrous ethanol and 1.8 mL deionized water; the lanthanide metal salt is selected from chlorides, acetylacetonates, acetates or nitrates; preferably, chlorides; the nickel salt is selected from nickel nitrate hexahydrate, nickel chloride or nickel acetylacetonate; preferably, nickel nitrate hexahydrate.

[0037] The reducing atmosphere includes: a pure nitrogen reducing atmosphere, a pure argon reducing atmosphere, a hydrogen / nitrogen mixed reducing atmosphere or a hydrogen / argon mixed reducing atmosphere, preferably a hydrogen / nitrogen mixed reducing atmosphere; further, the volume ratio of nitrogen to hydrogen is 50:1, 40:1, 30:1, 20:1, 10:1, preferably 20:1.

[0038] Furthermore, the calcination treatment in a reducing atmosphere is: calcination treatment is performed in a reducing atmosphere using a tubular furnace, and the calcination treatment conditions are calcination at 400-600° C. for 30-120 min, preferably, calcination at 500° C. for 60 min.

[0039] The present invention provides a lanthanide metal oxide modified nickel-based catalyst prepared by adopting the preparation method of the lanthanide metal oxide modified nickel-based catalyst.

[0040] Furthermore, the lanthanide metal oxide modified nickel-based catalyst is Ni-CeO x / C、Ni-NdO x / C or Ni-SmO x / C electrocatalyst, preferably Ni-SmO x / C electrocatalyst.

[0041] The present invention applies the lanthanide metal oxide modified nickel-based catalyst to alkaline hydrogen oxidation reaction and uses it as a MOF derivative electrocatalyst for alkaline hydrogen oxidation reaction. The catalyst Ni-SmO x / C In alkaline HOR, the exchange current density normalized to the metal mass ( j 0,m ) is 15.49 mA mg -1 , the exchange current density normalized to the electrochemical specific surface area ( j 0,s ) is 0.045 mA cm -2 , about five times that of the comparison sample Ni / C, and has excellent catalytic performance. x / C and Ni-NdO x / C compared to Ni-SmO x / C is slightly insufficient, but it also shows super high catalytic activity compared with the comparison sample Ni / C.

[0042] The invention has universal applicability and is applicable to all lanthanide metals, and exhibits excellent catalytic performance.

[0043] The preparation method and application of the lanthanide metal oxide modified nickel-based catalyst provided by the present invention are further described in detail below through specific examples. Example 1

[0044] Ni-SmO x Preparation method of / C electrocatalyst: 380.7 mg (1.31 mmol) of nickel nitrate hexahydrate, 33.6 mg (0.13 mmol) of samarium chloride and 89.2 mg (0.45 mmol) of 2,5-dihydroxyterephthalic acid were dissolved in a mixed solvent consisting of 30 mL of DMF (0.39 mol), 1.8 mL of deionized water (0.1 mol) and 1.8 mL of anhydrous ethanol (0.03 mol). The total amount of the solvent is 0.52 mol. The total amount of the solvent can be appropriately relaxed to 4000-6000 times the molar amount of samarium chloride, i.e. 0.39-0.78 mol. The amount of deionized water can be 1.6-2.0 mL, and the amount of anhydrous ethanol can be 1.6-2.0 mL.

[0045] The obtained solution was further ultrasonically treated, and after complete dissolution, it was placed in a 100 mL Teflon-lined stainless steel autoclave and heated at 120 °C for 24 h. After cooling naturally to room temperature, the sample was collected by centrifugation, and the obtained product was washed three times with ethanol and dried in vacuum at room temperature. Finally, the dried sample was placed in a quartz boat in the center of a tube furnace and calcined at 500 °C for 60 min in a reducing atmosphere with a volume ratio of nitrogen to hydrogen of 20:1 to obtain Ni-SmO x / C. The catalyst of Example 1 with different proportions was prepared by feeding metal salts with a total molar mass of 1.44 mmol in different proportions.

[0046] Comparative Example 1 Preparation method of Ni / C electrocatalyst: 418.8 mg (1.44 mmol) of nickel nitrate hexahydrate and 2,5-dihydroxyterephthalic acid (89.2 mg) were dissolved in a mixed solvent consisting of 30 mL DMF, 1.8 mL deionized water and 1.8 mL anhydrous ethanol. The obtained solution was further ultrasonicated and completely dissolved, then loaded into a 100 mL Teflon-lined stainless steel autoclave and heated at 120 °C for 24 h. After cooling naturally to room temperature, the sample was collected by centrifugation, and the obtained product was washed three times with ethanol and dried in vacuum at 60 °C. Finally, the dried sample was placed in a quartz boat in the center of a tube furnace and calcined at 500 °C for 60 min in a reducing atmosphere with a volume ratio of nitrogen to hydrogen of 20:1 to obtain Ni / C. Example 2

[0047] Ni-CeO x Preparation method of / C electrocatalyst: 380.7 mg (1.31 mmol) of nickel nitrate hexahydrate, 32.3 mg (0.13 mmol) of cerium chloride, and 89.2 mg (0.45 mmol) of 2,5-dihydroxyterephthalic acid were dissolved in a mixed solvent consisting of 30 mL of DMF, 1.8 mL of deionized water, and 1.8 mL of anhydrous ethanol. The obtained solution was further ultrasonicated and, after complete dissolution, was placed in a 100 mL Teflon-lined stainless steel autoclave and heated at 120 °C for 24 h. After cooling naturally to room temperature, the sample was collected by centrifugation, and the obtained product was washed three times with ethanol and dried in vacuum at 60 °C. Finally, the dried sample was placed in a quartz boat in the center of a tube furnace and calcined at 500 °C for 60 min in a reducing atmosphere with a volume ratio of nitrogen to hydrogen of 20:1 to obtain Ni-CeO x / C. Example 3

[0048] Ni-NdO xPreparation method of / C electrocatalyst: 380.7 mg (1.31 mmol) of nickel nitrate hexahydrate, 32.8 mg (0.13 mmol) of neodymium chloride, and 89.2 mg (0.45 mmol) of 2,5-dihydroxyterephthalic acid were dissolved in a mixed solvent consisting of 30 mL of DMF, 1.8 mL of deionized water, and 1.8 mL of anhydrous ethanol. The obtained solution was further ultrasonicated and, after complete dissolution, placed in a 100 mL Teflon-lined stainless steel autoclave and heated at 120 °C for 24 h. After naturally cooling to room temperature, the sample was collected by centrifugation, and the obtained product was washed three times with ethanol and dried in vacuum at 60 °C. Finally, the dried sample was placed in a quartz boat in the center of a tube furnace and calcined at 500 °C for 60 min in a reducing atmosphere with a volume ratio of nitrogen to hydrogen of 20:1 to obtain Ni-NdO x / C.

[0049] 1. Physical and chemical performance analysis of the catalysts prepared in Examples 1-3 and Comparative Example 1: Related results such as Figure 1-10 As shown. Figure 1 It can be seen from the X-ray powder diffraction curve (XRD) in a that the XRD diffraction peak positions of the catalyst MOF precursor powders prepared in Examples 1-3 and Comparative Example 1 are basically consistent with the XRD diffraction peak positions of the cif files obtained on the CCDC website, thus proving the successful formation of the lanthanide gold Ni-MOF-74 precursor. In addition, Figure 1 As shown in Figure b, the crystal configuration of the Ni-based MOF derivative material is a face-centered cubic structure. The strongest peaks (111), (200), and (220) in the figure are consistent with the Ni standard card (PDF#87-0712), and no impurity peaks appear, indicating the successful preparation of the Ni-based MOF derivative material. Due to the small size effect of the nanoparticles, the diffraction peaks in the XRD patterns of the catalysts prepared in Examples 1-3 are broadened to varying degrees.

[0050] from Figure 2-5 The scanning electron microscope (SEM) images show that the morphology of the catalyst is in the form of nanospheres, which are formed by the aggregation of nanoparticles. The catalyst prepared by this method is relatively stable, and the morphology does not change much before and after calcination. Examples 1-3 and Comparative Example 1 well inherit the structure of the MOF precursor and meet the requirements of being an alkaline electrocatalyst.

[0051] from Figure 6-9The transmission electron microscope (TEM) images show that the morphology of the catalysts after calcination is in the form of nanoparticles, which further proves that the nanosphere morphology of the catalyst in the SEM is formed by the aggregation of nanoparticles. The average particle size of the electrocatalysts prepared in Examples 1-3 and Comparative Example 1 is about 7 nm, among which Ni-SmO x / C catalyst has the smallest average particle size, reaching 6.16 nm, indicating that Ni-SmO x / C catalysts have more active sites and a larger surface area, which can more effectively adsorb reactant molecules and promote the catalytic reaction.

[0052] like Fig.10 The X-ray photoelectron spectroscopy (XPS) in a shows that Ni-SmO x There are three characteristic peaks at 852.23 eV, 855.03 eV and 859.93 in the Ni 2p spectrum of / C, which correspond to the three forms of Ni metal state, Ni oxidation state and Ni satellite peak, respectively, proving the existence of Ni in the catalyst. x The Ni / C catalyst was compared with the Ni / C catalyst prepared in Comparative Example 1, and it was found that the peak of Ni species shifted positively, which further verified the Ni-SmO x Electron transfer in C / C electrocatalysts. Fig.10 As shown in b, the Ni-SmO prepared in Example 1 x The XPS spectrum of Sm 3d of the Ni-SmO / C catalyst contains a pair of characteristic peaks, which are characteristic peaks of Sm oxides, indicating that the Ni-SmO x The Sm in the Mg / C catalyst exists in an oxidized form.

[0053] 2. HOR performance test and analysis of the catalysts prepared in Examples 1-3 and Comparative Example 1: First, prepare the working electrode: add 1 mg of XC-72 carbon powder to 4 mg of the catalyst prepared in Examples 1-3 and the catalyst in Comparative Example 1, then add 1 mL of isopropanol solvent containing 0.05 wt% Nafion, mix, and ultrasonicate for 60 min to form a uniform black solution. Polish the glassy carbon (GC) electrode with a diameter of 5 mm with 0.05 mm γ-alumina powder, and then clean it with ultrapure water and ethanol to make the electrode surface smooth. After natural air drying, 2×6.0 μL of black solution was dripped on the electrode surface, and electrochemical measurement was performed after air drying in air.

[0054] The electrochemical tests were carried out on a CHI 760E electrochemical workstation. The GC electrode modified with the electrocatalyst was used as the working electrode, the graphite rod was used as the counter electrode, and the saturated calomel electrode in 0.1 M KOH was used as the reference electrode. In this study, all operations were carried out at a constant temperature of 303 (±0.1) K, and all measured potentials refer to the reversible hydrogen electrode (RHE) potential with iR compensation. The catalyst was pretreated by cyclic voltammetry (CV) under 0.1 M KOH saturated with N2, and the voltammetry curve of the catalyst was stable in the range of −0.08 to 0.48. Then, the saturated H2 was continued with a scan rate of 5 mV s −1 The polarization curve of the catalyst was measured from −0.08 to 0.12 V at an RDE speed of 2500 rpm. The scan rate was 50 mV s −1 The cyclic voltammetry curve of the catalyst was tested from −0.08 to 0.48 V at an RDE speed of 1600 rpm. The electrochemically active surface area (ECSA) can be calculated from the CV curve.

[0055] The results of the HOR test are as follows: Catalyst Ni-SmO prepared in Example 1-3 x / C、Ni-CeO x / C、Ni-NdO x The catalysts Ni / C and Comparative Example 1 were prepared by rotating disk electrode in H2-saturated 0.1 M KOH electrolyte at a rotation speed of 2500 rpm and a voltage of 5 mV s -1 The polarization curve of the catalyst was recorded at a scan rate of Fig.11 As shown, Ni-SmO x / C electrocatalyst has the most significant apparent reaction activity.

[0056] In order to eliminate the interference of H2 mass transfer, the kinetic current density ( j k ), first of all, the limiting diffusion current density of these substances ( j d ) was studied. Generally, the Ni-SmO prepared in Example 1 x The polarization curves of / C measured at different speeds from 2500 to 625 rpm are shown in Fig.12 As shown in a. Fig.12 As shown in b, Fig.12 When the overpotential of a is 12 mV, the corresponding Koutecky-Levich plot is constructed, and its slope (1 / Bc 0) is 14.02 cm 2 mA -1 rpm 1 / 2, which means that at 2500 rpm, 0.0014 mA cm -2 of j d Then, using the Koutecky-Levich equation, we get j k At the same time, the catalysts prepared in Examples 1-3 and Comparative Example 1 were measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). On this basis, after the Ni mass was normalized, Ni-SmO x / C、Ni-CeO x / C、Ni-NdO x / C and Ni / C at 10 mV j k,m 0.872, 0.295, 0.386 and 0.149 mA mg respectively -1 .

[0057] like Fig.13 As shown, according to the Butler-Volmer equation, j k The Tafel plot of potential and exchange current density ( j 0 ).after, j 0 It can be further normalized by the metal mass to obtain the mass activity ( j 0,m ), Ni-SmO x / C j 0,m (15.49 mA mg -1 ) than Ni / C (2.15 mA mg PGM -1 ) is 7-8 times higher, while Ni-CeO x / C and Ni-NdO x / C j 0,m (7.83 mA mg -1 and 5.24 mA mg -1 ) is also higher than Ni / C (2.15 mA mg PGM -1 ) is 2-4 times higher.

[0058] like Fig.14 As shown, calculation j 0 Another method is to perform linear fitting based on the approximate Butler-Volmer formula. x / C has excellent HOR performance, which is close to the nonlinear fitting result.

[0059] like Fig.15 As shown in Figure 2, the cyclic voltammetry (CV) curve can be used to calculate its electrochemically active specific surface area (ECSA). j 0 , expressed as specific activity ( j 0,s ). Ni-SmO prepared in Example 1 x / C j 0,s The value is 0.045 mA cm -2 , five times higher than Ni / C and higher than most Ni-based non-precious HOR electrocatalysts.

[0060] Different proportions of Ni-SmO prepared in Example 1 x The polarization curve measured by / C is as follows Fig.16 As shown, the molar ratio of lanthanide metal salt to nickel salt is 1:10. When the potential is greater than zero, Ni 10 -SmO x / C has the highest potential, higher than Ni5-SmO x / C and Ni 15 -SmO x / C, has the best catalytic performance. It can be seen that when the lanthanide metal salt feed is relatively low, the rare earth metal content is low and cannot play a good modification role. When the lanthanide metal salt feed is relatively high, it will affect the porosity of the catalyst, increase the average particle size of the catalyst, and then inhibit the catalytic activity of the catalyst.

[0061] In summary, the present invention provides a lanthanide metal oxide modified nickel-based catalyst. A MOF-based precursor is obtained by a solvothermal method, and the reaction precursor is calcined in a reducing atmosphere to obtain a lanthanide metal oxide modified nickel-based catalyst. The catalyst is a non-Pt MOF-based derivative material, which is used for efficient alkaline HOR, reduces production costs, is suitable for commercial mass production, and broadens the types of catalysts. In addition, the catalyst utilizes the oxophilicity of lanthanide metals, which is beneficial to optimize the binding energy of intermediates, especially enhance OHBE, greatly improve the alkaline hydrogen oxidation activity, and has great application prospects in the field of alkaline HOR. Specifically, the present invention uses nickel nitrate hexahydrate as a nickel metal source, chloride as a lanthanide metal source, 2,5-dihydroxyterephthalic acid as a precursor ligand, and a mixed solvent consisting of 30 mL DMF, 1.8 mL anhydrous ethanol and 1.8 mL deionized water to prepare a catalyst Ni-SmO x / C. In alkaline HOR, the catalyst has an exchange current density normalized to the metal mass ( j 0,m) is 15.49 mA mg -1 , the exchange current density normalized to the electrochemical specific surface area ( j 0,s ) is 0.045 mA cm -2 , far exceeding the comparison sample Ni / C, and has excellent HOR catalytic performance. x / C and Ni-NdO x / C compared to Ni-SmO x / C is slightly insufficient, but it also shows super high catalytic activity compared with the comparison sample Ni / C.

[0062] It should be noted that those skilled in the art should understand that the nickel metal source may also be one of nickel acetylacetonate or nickel chloride, which is not exhaustively listed in the embodiments of the present invention. The preparation method provided by the present invention can successfully prepare a lanthanide metal oxide modified nickel-based catalyst, such as Ni-LaO x / C or Ni-PrO x / C, and all showed high catalytic activity.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a lanthanide metal oxide modified nickel-based catalyst, characterized in that The method comprises the following steps: preparing a Ni-MOF-74 catalyst precursor introduced with lanthanide metal ions by a solvent thermal method, and then calcining the precursor in a reducing atmosphere to obtain a lanthanide metal oxide-modified nickel-based catalyst.

2. The method for preparing a lanthanide metal oxide modified nickel-based catalyst as claimed in claim 1, characterized in that: The lanthanide metal is Ce, Nd or Sm.

3. The method for preparing a lanthanide metal oxide modified nickel-based catalyst as claimed in claim 1, characterized in that: The solvent thermal method for preparing the Ni-MOF-74 catalyst precursor introduced with lanthanide metal ions comprises the following steps: dissolving lanthanide metal salt, nickel salt and 2,5-dihydroxyterephthalic acid in a mixed solvent, then transferring them to a reactor, heating for reaction, naturally cooling to room temperature, centrifuging and washing, and then vacuum drying to obtain.

4. The method for preparing a lanthanide metal oxide modified nickel-based catalyst as claimed in claim 3, characterized in that: The molar ratio of the lanthanide element to the nickel element in the lanthanide metal salt and the nickel salt is 1:(5-15); the molar amount of 2,5-dihydroxyterephthalic acid is 3.0-3.4 times the sum of the molar amounts of the lanthanide element and the nickel element; the mixed solvent is a mixed solvent composed of DMF, anhydrous ethanol and deionized water, the volume ratio of DMF, anhydrous ethanol and deionized water is 30:(1.6-2.0):(1.6-2.0), and the total molar amount is 3000-6000 times the molar amount of the lanthanide element; the lanthanide metal salt is a chloride, an acetylacetonate, an acetate or a nitrate; the nickel salt is nickel nitrate hexahydrate, nickel chloride or nickel acetylacetonate.

5. The method for preparing a lanthanide metal oxide modified nickel-based catalyst as claimed in claim 4, characterized in that: The molar ratio of the lanthanide element to the nickel element in the lanthanide metal salt and the nickel salt is 1:10; the molar amount of 2,5-dihydroxyterephthalic acid is 3.2 times the sum of the molar amounts of the lanthanide element and the nickel element; the mixed solvent is a mixed solvent composed of DMF, anhydrous ethanol and deionized water, the volume ratio of DMF, anhydrous ethanol and deionized water is 30:1.8:1.8, and the total amount is 4000 times the amount of the lanthanide element.

6. The method for preparing a lanthanide metal oxide modified nickel-based catalyst as claimed in claim 3, characterized in that: The heating reaction temperature is 100-120°C, and the heating reaction time is 12-36 h; the centrifugal washing speed is 8000-10000 rpm, and ethanol, methanol or isopropanol is used for washing; the vacuum drying temperature is 20-80°C.

7. The method for preparing a lanthanide metal oxide modified nickel-based catalyst according to claim 1, characterized in that: The reducing atmosphere includes: pure nitrogen reducing atmosphere, pure argon reducing atmosphere, hydrogen / nitrogen mixed reducing atmosphere or hydrogen / argon mixed reducing atmosphere; the calcination treatment is carried out in a reducing atmosphere using a tubular furnace, and the calcination treatment conditions are calcination at 400-600°C for 30-120 min.

8. A lanthanide metal oxide modified nickel-based catalyst, characterized in that: The catalyst is prepared by the method for preparing a lanthanide metal oxide-modified nickel-based catalyst according to any one of claims 1 to 7.

9. The lanthanide metal oxide modified nickel-based catalyst as claimed in claim 8, characterized in that: The lanthanide metal oxide modified nickel-based catalyst is Ni-CeO x / C、Ni-NdO x / C or Ni-SmO x / C catalyst.

10. The use of the lanthanide metal oxide modified nickel-based catalyst according to claim 8 or 9, characterized in that: The catalyst is used as a MOF derivative electrocatalyst in an alkaline hydrogen oxidation reaction.

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