Ce-nimo / nf catalyst, preparation method and application thereof in field of biomass electrooxidation

Abstract

The application discloses a Ce-NiMo / NF catalyst, a preparation method and application of the catalyst in the field of biomass electro-oxidation, and belongs to the technical field of catalyst preparation. The application constructs a heterogeneous interface of CeO2 and NiMo by doping trace rare earth element Ce into transition metal NiMo, creates a more favorable bonding environment, improves active oxygen adsorption capacity, and thus improves furfural oxidation activity. Organic electro-oxidation reaction is used to replace anode OER reaction, so that large current density biomass electro-oxidation coupled with water electrolysis is driven at a lower overpotential, and a current density of 500 mA cm ‑2 of industrial water decomposition can be driven at a low voltage of 1.39 V vs RHE. The current density is only reduced by 6% after continuous testing in an electrolytic cell for 200 h, and the catalyst exhibits excellent electrocatalytic activity and stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a Ce-NiMo / NF catalyst, a preparation method and application thereof in the field of biomass electro-oxidation. BACKGROUND

[0002] The raw material for water electrolysis to produce hydrogen is clean and environmentally friendly, and the electrolysis products are only H2 and O2. However, the anode oxygen evolution reaction (OER) has a slow reaction rate, resulting in a high oxygen evolution overpotential, thereby directly reducing the overall energy conversion efficiency and increasing the electrolysis cost. In the water electrolysis to produce hydrogen, the anode product O2 has a low added value, and the H2 and O2 produced by the two poles are prone to mixing in the reactor, which poses a safety hazard. Therefore, by using biomass platform compounds such as five-hydroxymethylfurfural (HMF), furfural (FA), glucose and glycerol as raw materials, biomass electro-oxidation coupled with water electrolysis to produce hydrogen can significantly reduce the overpotential of the reaction and achieve efficient production of hydrogen and high-added-value chemicals. The oxidation process of FA is a complex process of electron and proton transfer. With the increase of the current density, the advantage of furfural electrochemical oxidation reaction (FOR) is gradually lost, resulting in a gradual increase in the oxidation potential of FA, and a decrease in the Faraday efficiency (FE) and selectivity. Therefore, it is urgent to develop a low-cost, high-catalytic-activity and high-stability catalytic electrode material.

[0003] Marisa Ketkaew et al. reported a method for preparing Pt / Au Janus particles as a bifunctional electrocatalyst by using a bipolar electrodeposition method. By using a bipolar electrochemical method, simultaneous electrochemical conversion of furfuryl alcohol and furfuryl alcohol was achieved by oxidation and reduction of furfuryl alcohol. However, these conversion reactions often rely on noble metal catalysts such as gold (Au), palladium (Pd) and platinum (Pt), and the high price and harsh reaction conditions greatly limit the application of noble metal catalysts in industrialization. Therefore, in order to improve the reaction efficiency of the electrocatalytic process, designing and preparing a high-efficiency and stable oxygen evolution electrocatalyst has become a key to the development of electrocatalytic hydrogen production technology. For the HER performance, since the precursor needs to be calcined at a high temperature, the performance of the catalyst with too large a surface area will decrease, and there is a problem that a large current density cannot be driven at a low overpotential. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a Ce-NiMo / NF catalyst, a preparation method and application thereof in the field of biomass electro-oxidation, so as to solve the technical problems of nickel-based catalysts that cannot drive a large current density at a low overpotential and have poor catalytic performance.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is to provide a preparation method of a Ce-NiMo / NF catalyst, comprising the following steps:

[0006] S1, pretreat the foamed nickel, then dissolve nickel salt, molybdenum salt, cerium salt and raw material one in water and stir for 15-25 min, then place the mixed solution and the pretreated foamed nickel (foamed nickel as a load substrate of nickel-based catalyst) in a hydrothermal reaction at 140-160 DEG C for 5-7 h to obtain a precursor Ce-NiMoO4 / NF; raw material one is ammonium fluoride or urea; the molar ratio of nickel salt, molybdenum salt, cerium salt and raw material one is 3-5:3-5:0.5-1.5:7-9;

[0007] S2, place the precursor Ce-NiMoO4 / NF in a reducing atmosphere and reduce at 500-600 DEG C for 1.5-2.5 h to obtain a catalyst Ce-NiMo / NF.

[0008] The rare earth element Ce has the possibility of dynamic adjustment for the electronic configuration of the d-band active center due to the empty or half-filled 4f electron shell structure and lower electronegativity, and enhances the spin-orbit coupling effect. The three-dimensional electron cloud configuration of the nickel-based catalyst promotes the effective transmission of electrons, and the unique property of the eg orbital acts as a "bridge" to deepen the interaction between the metal site and the oxygen atom, so that the furfural molecule can more smoothly undergo the adsorption, conversion and desorption stages in the electrocatalytic oxidation process, and the optimization of the reaction path and the improvement of the efficiency are realized.

[0009] On the basis of the above technical solution, the application can also be improved as follows:

[0010] Further, the pretreatment process of the foamed nickel is to place the foamed nickel in ethanol and hydrochloric acid respectively and ultrasonic treat at 15-25 KHz for 15-25 min.

[0011] Further, the nickel salt is nickel nitrate or nickel sulfate, the molybdenum salt is sodium molybdate or ammonium molybdate, and the cerium salt is cerium nitrate or cerium sulfate.

[0012] Further, the heating rate during the hydrothermal reaction is 2-3 DEG C / min; and the heating rate during the reduction reaction is 4-5 DEG C / min.

[0013] Further, the temperature of the hydrothermal reaction is 150 DEG C, and the time is 6 h.

[0014] Further, the temperature of the reduction reaction is 550 DEG C, and the time is 2 h.

[0015] Further, the reducing atmosphere is a mixture of H2 and N2 in a volume ratio of 5-15:85-95.

[0016] The application also discloses a Ce-NiMo / NF catalyst prepared by the preparation method.

[0017] The application also discloses an application of the Ce-NiMo / NF catalyst in the field of biomass electro-oxidation.

[0018] The beneficial effects of the present application are:

[0019] 1. The present application constructs a heterogeneous interface of CeO2 and NiMo by doping a small amount of rare earth element Ce into transition metal NiMo, creates a more favorable bonding environment, improves the active oxygen adsorption capacity, and thus enhances the furfural oxidation activity. And using organic electro-oxidation reaction instead of anode OER reaction, it realizes driving large current density of biomass electro-oxidation coupled with water electrolysis at low overpotential, and shows excellent electrocatalytic activity and stability.

[0020] 2. When the Ce-NiMo / NF catalyst prepared by the present application is used for furfural electro-oxidation coupled with water electrolysis to produce hydrogen, it can drive a 500mA cm -2 of industrial water decomposition current density at a low voltage of 1.39V vs RHE, and its catalytic activity is significantly better than RuO2 (500mA cm -2 at 1.63V vs RHE). At the same time, the corresponding furan acid (FAC) selectivity and Faraday efficiency (FE) reach 99.43% and 97.68%, respectively.

[0021] 3. The electrolytic cell using the Ce-NiMo / NF prepared by the present application as anode electrode only needs a cell voltage of 1.9V to drive a current density of 580mA cm -2 under industrial conditions; after continuous testing in the electrolytic cell for 200h, the current density only decreases by 6%, showing excellent electrochemical stability. The Ce-NiMo / NF catalyst is used for biomass oxidation of HMF, glucose and glycerol, and all show good electrocatalytic activity. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the preparation flowchart of the present application;

[0023] Figure 2 is the SEM image of Ce-NiMo / NF with different Ce concentrations, wherein Fig. (a) is the SEM image of Ce-NiMo / NF with a Ce concentration of 5mM, Fig. (b) is the SEM image of Ce-NiMo / NF with a Ce concentration of 10mM, Fig. (c) is the SEM image of Ce-NiMo / NF with a Ce concentration of 15mM, and Fig. (d) is the SEM image of Ce-NiMo / NF with a Ce concentration of 20mM;

[0024] Figure 3 is the XRD image of Ce-NiMoO4 / NF;

[0025] Figure 4XRD patterns of Ni, NiMo / NF and Ce-NiMo / NF;

[0026] Figure 5 XRD local magnification of Ni, NiMo / NF and Ce-NiMo / NF;

[0027] Figure 6 XPS full spectrum of Ce-NiMo / NF;

[0028] Figure 7 XPS spectrum of Ni 2p in NiMo / NP and Ce-NiMo / Ni / NF;

[0029] Figure 8 XPS spectrum of Ce 3d in Ce-NiMo / NF;

[0030] Figure 9 XPS spectrum of Co 2p in NiMo / NF and Ce-NiMo / NF;

[0031] Figure 10 XPS spectrum of O 1s in NiMo / NF and Ce-NiMo / NF;

[0032] Figure 11 EPR test results of Ce-NiMo / NF;

[0033] Figure 12 SEM image of Ce-NiMo / NF;

[0034] Figure 13 TEM image of Ce-NiMo / NF at different resolutions;

[0035] Figure 14 HRTEM image of Ce-NiMo / NF;

[0036] Figure 15 SAED image of Ce-NiMo / NF;

[0037] Figure 16 AC-HADDF-STEM image;

[0038] Figure 17 SAED image of Ni atomic distance;

[0039] Figure 18 SAED image of Mo atomic distance;

[0040] Figure 19 SAED image of Ce atomic longitudinal distance;

[0041] Figure 20 SAED image of Ce atomic lateral distance;

[0042] Figure 21 STEM image of Ce-NiMo / NF nanorods;

[0043] Figure 22 Activity comparison of Ce-NiMo / NF at different reduction temperatures;

[0044] Figure 23 XRD patterns of Ce-NiMo / NF at different reduction temperatures;

[0045] Figure 24 SEM images of Ce-NiMo / NF at different reduction temperatures, wherein, Fig. (a) is the SEM image of Ce-NiMo / NF at 450℃, Fig. (b) is the SEM image of Ce-NiMo / NF at 500℃, Fig. (c) is the SEM image of Ce-NiMo / NF at 550℃, and Fig. (d) is the SEM image of Ce-NiMo / NF at 600℃;

[0046] Figure 25 XRD pattern of Ce-NiMo / NF at 600℃ reduction temperature;

[0047] Figure 26 Comparison of LSV of electrolysis of water and electrochemical oxidation of furfural;

[0048] Figure 27 LSV comparison chart of different materials;

[0049] Figure 28 FOR and OER polarization curves of Ce-NiMo / NF and RuO2 / NF;

[0050] Figure 29 Tafel slope chart;

[0051] Figure 30 EIS curves of different nickel-based materials in FA solution;

[0052] Figure 31 Cyclic voltammograms of different nickel-based materials at different scan rates;

[0053] Figure 32 Changes of FA, FAC and FAL concentrations with charge consumption;

[0054] Figure 33 FAC selectivity and Faraday efficiency (FE) chart of Ce-NiMo / NF material;

[0055] Figure 34 Change chart of selectivity and FE of Ce-NiMo / NF after 6 cycles;

[0056] Figure 35 Furfuryl alcohol consumption for 6 cycles;

[0057] Figure 36 SEM image of Ce-NiMo / NF after 6 cycles;

[0058] Figure 37 Schematic diagram of flow cell device;

[0059] Figure 38 LSV curve of furfural electrolysis;

[0060] Figure 39 Long-term stability of Ce-NiMo / NF;

[0061] Figure 40 LSV curve of Ce-NiMo / NF under different substrates. DETAILED DESCRIPTION

[0062] The specific embodiments of the present application are described below to enable those skilled in the art to understand the present application, and the specific conditions are not specified in the examples, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer, and the reagents or instruments used are not specified by the manufacturer, which are all conventional products that can be purchased on the market. But it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application as defined and determined by the appended claims, and all inventions utilizing the concept of the present application are within the scope of protection.

[0063] Example 1

[0064] A preparation method of a Ce-NiMo / NF catalyst, as shown in Figure 1 , comprising the following steps:

[0065] S1, the foamed nickel was placed in ethanol and hydrochloric acid respectively, and was ultrasonically treated at 15 KHz for 25 min; then nickel nitrate Ni(NO3)2·6H2O (0.407 g, 40 mM), sodium molybdate Na2MoO4·2H2O (0.339 g, 40 mM), cerium nitrate Ce((NO3)3·6H2O) (0.152 g, 10 mM) and ammonium fluoride NH4F (0.1036 g, 80 mM) were dissolved in 35 mL of water and stirred for 15 min, then the mixed solution was added to the 1×1 cm 2 The pretreated foamed nickel was mixed, and was heated from room temperature to 140℃ at a heating rate of 2℃ / min, and was hydrothermally reacted for 7h to obtain a precursor Ce-NiMoO4 / NF;

[0066] S2, the precursor Ce-NiMoO4 / NF is placed in a reducing atmosphere (H2:N2=5:95, v:v), then the temperature is raised from room temperature to 500°C at a rate of 4°C / min, and reduction reaction is carried out for 2.5h to obtain the catalyst Ce-NiMo / NF.

[0067] Example 2

[0068] A preparation method of a Ce-NiMo / NF catalyst, as shown in Figure 1 , comprises the following steps:

[0069] S1, the nickel foam is respectively placed in ethanol and hydrochloric acid, and is sequentially ultrasonically treated at 25KHz for 15min; then nickel sulfate (0.407g, 40mM), ammonium molybdate (0.339g, 40mM), cerium nitrate Ce((NO3)3·6H2O) (0.152g, 10mM) and ammonium fluoride NH4F (0.1036g, 80mM) are dissolved in 35mL water and stirred for 25min, and then the mixed solution is mixed with 1×1cm 2 The pretreated nickel foam is mixed, the temperature is raised from room temperature to 160°C at a rate of 3°C / min, and hydrothermal reaction is carried out for 5h to obtain the precursor Ce-NiMoO4 / NF;

[0070] S2, the precursor Ce-NiMoO4 / NF is placed in a reducing atmosphere (H2:N2=15:85, v:v), then the temperature is raised from room temperature to 600°C at a rate of 5°C / min, and reduction reaction is carried out for 1.5h to obtain the catalyst Ce-NiMo / NF.

[0071] Example 3

[0072] A preparation method of a Ce-NiMo / NF catalyst, as shown in Figure 1 , comprises the following steps:

[0073] S1, the nickel foam is respectively placed in ethanol and hydrochloric acid, and is sequentially ultrasonically treated at 20KHz for 20min; then nickel nitrate Ni(NO3)2·6H2O (0.407g, 40mM), sodium molybdate Na2MoO4·2H2O (0.339g, 40mM), cerium nitrate Ce((NO3)3·6H2O) (0.152g, 10mM) and ammonium fluoride NH4F (0.1036g, 80mM) are dissolved in 35mL water and stirred for 20min, and then the mixed solution is mixed with 1×1cm 2 The pretreated nickel foam is mixed, the temperature is raised from room temperature to 150°C at a rate of 2°C / min, and hydrothermal reaction is carried out for 6h to obtain the precursor Ce-NiMoO4 / NF;

[0074] S2, the precursor Ce-NiMoO4 / NF was placed in a reducing atmosphere (H2:N2=10:90, v:v), then the temperature was raised from room temperature to 550°C at a rate of 4°C / min, and reduced for 2h to obtain the catalyst Ce-NiMo / NF, named as Ce 10 .

[0075] Example 4

[0076] The difference between this example and Example 3 is that the amount of cerium nitrate added is adjusted to 5mM, and the rest of the implementation conditions are the same as those of Example 3, to obtain the catalyst Ce-NiMo / NF, named as Ce5.

[0077] Example 5

[0078] The difference between this example and Example 3 is that the amount of cerium nitrate added is adjusted to 15mM, and the rest of the implementation conditions are the same as those of Example 3, to obtain the catalyst Ce-NiMo / NF, named as Ce 15 .

[0079] Comparative Example

[0080] The difference between this example and Example 3 is that the amount of cerium nitrate added is adjusted to 5mM, and the rest of the implementation conditions are the same as those of Example 3, to obtain the catalyst Ce-NiMo / NF, named as Ce5.

[0081] The Ce-NiMo / NF material used in the following experiments is the Ce-NiMo / NF catalyst prepared in Example 3.

[0082] Example 1 Material Characterization

[0083] 1. Micro-morphology of Ce-NiMo / NF

[0084] The morphology of Ce-NiMo / NF with different Ce contents (Ce0, Ce5, Ce 10 and Ce 15 ) is shown in Figure 2 . Compared with the densely packed nanorods in the NiMo / NF catalyst without Ce doping (Ce0), the spatial structure of Ce5, Ce 10 and Ce 15 clusters indicates that reasonable Ce doping promotes the growth of clusters and exposes more active sites.

[0085] 2. X-ray Diffraction Analysis

[0086] To further confirm the crystal structure, the composition analysis of the Ce-NiMo / NF material was carried out, and the X-ray diffraction (XRD) pattern is shown in Figure 3As shown. The diffraction peaks at 2θ–44.5°, 51.8° and 76.4° correspond to the (111), (200) and (220) crystal planes of Ni, and the diffraction peaks at 37.2°, 43.2° and 62.9° correspond to the (111), (200) and (110) crystal planes of NiO, respectively (PDF#44-1159). It can be seen that after hydrogen reduction, NiMoO4 and a part of NiO species are reduced to Ni( Figure 4 Due to the low Ce content, no Ce characteristic peak is shown in the XRD pattern. It is found that the intensity of Ni's characteristic diffraction peak is significantly weakened. The (111) crystal plane of Ni is locally enlarged ( Figure 5 ), showing that the (111) crystal plane of Ni shifted by 0.37° at a low angle after Ce doping. This is due to the 3+ The ionic radius is larger than that of Ni 2+ , which causes the Ni lattice to be distorted, which is conducive to the generation of more defects. It is preliminarily confirmed that Ce has been successfully doped into the NiMo material.

[0087] 3. X-ray photoelectron spectroscopy analysis

[0088] The chemical environment and electronic structure of the Ce-NiMo / NF catalyst prepared in Example 3 were investigated by X-ray photoelectron spectroscopy (XPS). Figure 6 As shown in Figure 2, the XPS spectrum of Ce-NiMo / NF shows the presence of Ce, Ni, Mo and O elements. Figure 7 As shown, the peaks at 881.79 and 901.61 eV belong to Ce 3+ , while the peaks at 879.12, 886.03, 892.94, 896.04, 899.19, and 905.04 eV belong to Ce 4+ .like Figure 8 As shown in the Mo 3d spectrum of NiMo / NF catalyst, the peaks at 223.02eV and 232.21eV are consistent with those at Mo 3+ The peaks at 229.48eV and 232.94eV are related to Mo 4+ The peaks at 231.45eV and 235.43eV are satellite peaks. After Ce doping, the peaks at 229.13eV and 232.32eV in Ce-NiMo / NF are related to Mo 3+ The peaks at 229.55eV and 233.01eV are related to Mo 4+ There is an obvious shift of 0.11 eV compared with NiMo / NF, indicating that the charge is transferred from NiMo / NF to Ce and that a certain degree of reduction of Mo oxide occurs during annealing in H2 atmosphere.

[0089] like Figure 9As shown in the Ni 2p spectrum of NiMo / NF, the peaks at 852.91 eV and 871.32 eV are related to NiO, the peaks at 855.95 eV and 873.70 eV are related to Ni 2+ 2p 3 / 2 , the peaks at 859.22 eV and 877.63 eV are related to Ni 2+ 2p 1 / 2 , and the peaks at 862.39 eV and 878.76 eV are satellite peaks. After Ce doping, the peaks at 852.95 eV and 871.36 eV in Ce-NiMo / NF are related to NiO, the peaks at 856.05 eV and 873.80 eV are related to Ni 2+ 2p 3 / 2 , the peaks at 858.83 eV and 877.24 eV are related to Ni 2+ 2p 1 / 2 , and the peaks at 862.27 eV and 880.68 eV are satellite peaks. The peaks move to a higher binding energy, indicating that the electronic interaction causes charge transfer. As shown in Figure 10 , the proportion of oxygen vacancies (Ov) in Ce-NiMo / NF is larger than that in NiMo / NF.

[0090] The EPR test was performed on Ce-NiMo / NF Figure 11 , and the results showed that there were a large number of defect sites in Ce-NiMo / NF. Combined with the XPS analysis results, it was shown that more oxygen vacancies were generated on the surface of the catalyst after the introduction of Ce, which helped to accelerate the oxidation reaction.

[0091] 4. Scanning electron microscope and transmission electron microscope analysis

[0092] Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to explore the micro-nano structure of Ce-NiMo / NF. As shown in Figure 12 and Figure 13 , the integrity of the NiMo nanorod structure and morphology was still maintained after Ce doping. Figure 14 and Figure 15 show the high-resolution TEM images of Ce-NiMo / NF. The lattice fringes with a spacing of 0.206 nm and 0.209 nm are directed to Ni(111), NiO(200) and CeO2(200), respectively, indicating the existence of a heterogeneous interface between NiMo and CeO2. In order to clearly confirm the existence of the heterogeneous interface between NiMo and CeO2, aberration-corrected (AC) high-angle annular dark-field scanning TEM (HAADF-STEM) measurement was performed Figure 16). The heterogeneous interface can be clearly observed according to the arrangement of atoms, and the close interface interaction between CeO2 and NiMo helps to cause local electronic configuration and internal electronic rearrangement, improve the active oxygen adsorption capacity, and thus improve the oxidation activity of the catalyst. As shown in Figure 17 and Figure 18 , the distance between Ni atoms and Mo atoms is (horizontal distance) and (vertical distance), respectively. Compared with the Cif of the Ni crystal, due to the larger atomic radius of Mo, the atomic spacing is increased. As shown in Figure 19 and Figure 20 , the horizontal and vertical distances between Ce atoms are measured to be and , respectively, which is consistent with the cubic structure and the Cif parameters of the CeO2 crystal. EDX element mapping Figure 21 also proves the uniform distribution of Ni, Mo and Ce on the nanorods.

[0093] Effect of reduction temperature on the catalytic activity of Ce-NiMo / NF catalyst

[0094] Comparing the catalytic activity and composition of Ce-NiMo / NF catalysts at different reduction temperatures, it is shown that the catalytic activity is best when the reduction temperature is 550°C Figure 22 . The crystal composition is the same when the reduction temperature is 450°C, 500°C and 550°C, and as the reduction temperature increases, the crystallinity of the crystal is better and better Figure 23 , and the nanorods grow more densely Figure 24 . When the reduction temperature is increased to 600°C, the surface morphology of the catalyst is changed, and a new phase is generated, which leads to the weakening of the catalytic activity Figure 25 .

[0095] Electrocatalytic activity

[0096] 1. Linear sweep voltammetry (LSV) test

[0097] The electrocatalytic activity of the furfural electrochemical oxidation reaction (FOR) and the anodic oxygen evolution reaction (OER) was studied in a three-electrode H-type electrolytic cell. The anode electrolyte of the experimental group was a 1 M potassium hydroxide solution containing 0.1 M furfural, and the anode electrolyte of the control group was a 1 M potassium hydroxide solution without furfural. The cathode electrolyte of both groups was 1 M potassium hydroxide, and the reaction solution volume was 30 mL, and the reaction temperature was 25°C. The specific steps are as follows: The electrochemical activity was tested using an electrochemical station (CHI1140C) in an H-type electrolytic cell with a three-electrode system. The reference electrode was Hg / HgO (1 M KOH), the counter electrode was a graphite sheet (2 cm x 2 cm x 2 mm), and the hydrothermally synthesized sample was used as the working electrode. All electrochemical tests were performed at room temperature (25°C). Before linear sweep voltammetry (LSV) testing, the activated electrode was subjected to 40 cyclic voltammetry (CV) cycles at a scan rate of 50 mV s -1 LSV was performed at a scan rate of 5 mV s -1 , using 30 mL of 1 M KOH solution and 0.1 M FA as the anode electrolyte, and using 30 mL of 1 M KOH solution as the cathode electrolyte, separated by an anion exchange membrane.

[0098] The results are shown in Figure 26 . When the anode electrolyte was only 1 M KOH (control group), there was a small oxidation peak at 1.38 V vs. RHE due to the oxidation of Ni 2+ to Ni 3+ , resulting in the need to apply a voltage of 1.66 V vs. RHE at a current density of 500 mA cm -2 to drive the oxygen evolution reaction. When the anode electrolyte was 1 M KOH and 0.1 M furfural (experimental group), a voltage of only 1.39 V vs. RHE was required to drive the furfural electrochemical oxidation reaction (FOR) at a current density of 500 mA cm -2 .

[0099] As shown in Figure 27 , Ce doping has better furfural electrochemical oxidation activity, with a voltage reduction of 90 mV compared to the NiMo / NF catalyst to reach a current density of 500 mA cm -2 , and a voltage reduction of 270 mV -2 ( Figure 28 ) compared to the RuO2 catalyst to reach a current density of 500 mA cm -2 at 1.63 V vs. RHE. The Ce-Ni / NF catalyst synthesized without Mo source has a large oxidation peak at 1.45 V vs. RHE due to the oxidation of Ni 2+ to Ni 3+ ​, which leads to a sharp decrease in its electrochemical activity. The precursor Ce-NiMoO4 / NF has a comparable electrochemical activity with the foam nickel substrate.

[0100] 2. Tafel slope analysis

[0101] To determine the effect of Ce doping on the reaction kinetics, Tafel slope analysis was performed according to the LSV curve, and the results are shown in Figure 29 The Tafel slope of Ce-NiMo / NF is 25.43 mV dec -1 , which is lower than that of NiMo / NF (29.42 mV dec -1 ), Ce-Ni / NF (32.32 mV dec -1 ), precursor Ce-NiMoO4 / NF (38.3 mV dec -1 ), and substrate NF (40.08 mV dec -1 ), indicating that the Ce-NiMo / NF catalyst has the highest FOR activity and the fastest reaction kinetics.

[0102] 3. Electrochemical impedance spectroscopy test

[0103] To further explore the catalytic activity of the catalyst, electrochemical impedance spectroscopy (EIS) was performed on the Ce-NiMo / NF material, and the results are shown in Figure 30 Ce-NiMo / NF exhibits the smallest Rct value, indicating faster charge transfer between the electrode and the electrolyte. Then, cyclic voltammetry (CV) was performed at different scan rates in the non-Faraday region range, as shown in Figure 31 Ce-NiMo / NF has the largest double-layer capacitance value (4.34 mF cm -2 ) and the largest electrochemical active surface area (108.5 cm 2 ), indicating that Ce-NiMo / NF has more active sites.

[0104] 4. Analysis of electrolysis products

[0105] After electrolysis, quantitative and qualitative analysis of the reaction products and by-products was performed using high-performance liquid chromatography. The specific steps are as follows: at 35°C, using a UV-visible detector (220 nm) and a C18 column (4.6 mm x 150 mm x 5 μm, pad set GWS), using a UV-visible detector (220 nm) and a C18 column (4.6 mm x 150 mm x 5 μm, pad set GWS) at 35°C at a flow rate of 0.6 mL min -1The flow rate of the stream was used to quantify and qualitatively analyze the product formation and reactant consumption in the potentiostatic electrolysis. The HPLC mobile phase consisted of a mixture of 50% water and 50% acetonitrile, and the instrument was calibrated using a standard curve generated from a commercial product for the quantitative determination of FA, FAC, and FAL. The electrochemical tests were performed at an anodic potential of 1.3 V vs. RHE.

[0106] The results, as shown in Figure 32 , show that the concentrations of furfural (FA) and furfuryl acid (FAC) both linearly change with the increase of electrolysis charge from 0 C to 400 C, and a trace amount of FAL is generated, which is likely to be generated by the disproportionation reaction of FA in a strong alkaline solution. The carbon balance during the reaction is always close to 100%, which indicates that the polymerization of furfural can be ignored.

[0107] Experimental Example 4 Stability of Ce-NiMo / NF Catalyst

[0108] By exploring the effects of different electrolysis potentials on the FAC selectivity and Faraday efficiency (FE) of the Ce-NiMo / NF electrode, as shown in Figure 33 , with the increase of the electrolysis potential, the Faraday efficiency of FAC gradually decreases, while the selectivity of FAC remains almost unchanged, which is due to the fact that with the increase of the potential, the competitiveness of OER continuously strengthens and consumes a considerable amount of electrolysis charge.

[0109] The stability of the Ce-NiMo / NF catalyst is shown in Figure 34 and Figure 35 , by continuously electrolyzing at an anodic potential of 1.39 V vs. RHE for 6 cycles, with each cycle consuming 300 C of charge, the selectivity of FAC decreases from 99.43% to 95.01%, and the Faraday efficiency decreases from 97.68% to 92.39%. In addition, after 6 complete electrolyses, the selectivity and Faraday efficiency of FAC only show a slight decrease, and the LSV curve changes little. As shown in the SEM image Figure 36 , the nanorod structure and the nanoparticles and nanoneedle-like structures on the nanorods still exist, which indicates that the Ce-NiMo / NF has good FOR stability.

[0110] Experimental Example 5 Cell Experiment

[0111] 1. By constructing a flow electrolysis cell (Ce-NiMo / NF(+)||NiPt4 / NM(-)) to simulate the industrial anodic furfural electro-oxidation coupled with cathodic hydrogen evolution reaction, the device schematic diagram is shown in Figure 37 , the anolyte of the experimental group is 1M potassium hydroxide solution containing 0.1M furfural, and the anolyte of the control group is 1M potassium hydroxide solution without furfural. The catholyte of the two groups is 1M potassium hydroxide, the reaction temperature is 50℃, and the anion exchange membrane uses a porous membrane ZP-1239.

[0112] The results are as follows Figure 38 As shown, it reaches 500mA cm -2 The cell voltage required for water electrolysis is 2.06V, while furfural electrolysis only requires 1.78V; furfural electrolysis only requires a cell voltage of 1.9V to achieve 580mA cm -2 The current density shows that the efficiency of furfural electrooxidation coupled with water electrolysis to produce hydrogen is better, and it has obvious thermodynamic and kinetic advantages over water electrolysis. Figure 39 As shown in the graph, the current density only decreased by 6% after 200 h of continuous testing in the electrolytic cell, indicating that the Ce-NiMo / NF catalyst has excellent electrochemical stability.

[0113] 2. The electrochemical activity was tested using an electrochemical station (CHI 1140C) in an H-type electrolytic cell with a three-electrode system. The reference electrode was Hg / HgO (1 M KOH), the counter electrode was a graphite sheet (2 cm × 2 cm × 2 mm), and the hydrothermally synthesized sample was used as the working electrode. All electrochemical tests were performed at room temperature (25°C). Before the linear sweep voltammetry (LSV) test, the activated electrode was charged at 50 mV s -1 40 voltammetry (CV) cycles were performed at a scan rate of 5 mV s -1 LSV was performed at a scan rate of 1.5 Å using 30 mL of 1 M KOH solution with 0.1 M HMF, glucose, and glycerol as the anode electrolyte and 30 mL of 1 M KOH solution as the cathode electrolyte, separated by an anion exchange membrane.

[0114] The results are as follows Figure 40 As shown in the results, the Ce-NiMo / NF catalyst exhibited good electrocatalytic activity in the oxidation of biomass such as HMF, glucose and glycerol.

Claims

1. A method for preparing a Ce-NiMo / NF catalyst, characterized by, The method comprises the following steps: S1, pretreating the foamed nickel, then dissolving a nickel salt, a molybdenum salt, a cerium salt and a raw material one in water and stirring for 15-25 min, then placing the mixed solution and the pretreated foamed nickel in a hydrothermal reaction at 140-160℃ for 5-7 h to obtain a precursor Ce-NiMoO4 / NF; the raw material one is ammonium fluoride or urea; the molar ratio of the nickel salt, the molybdenum salt, the cerium salt and the raw material one is 3-5:3-5:0.5-1.5:7-9; S2, placing the precursor Ce-NiMoO4 / NF in a reducing atmosphere and reducing at 500-600℃ for 1.5-2.5 h to obtain a catalyst Ce-NiMo / NF; the reducing atmosphere is a mixture of H2 and N2 at a volume ratio of 5-15:85-95; a heterogeneous interface is formed between CeO2 and NiMo in the Ce-NiMo / NF.

2. The method for preparing the Ce-NiMo / NF catalyst according to claim 1, characterized by, The pretreatment process of the foamed nickel is: placing the foamed nickel in ethanol and hydrochloric acid respectively and ultrasonic treating at 15-25 KHz for 15-25 min.

3. The method for preparing the Ce-NiMo / NF catalyst according to claim 1, characterized by, The nickel salt is nickel nitrate or nickel sulfate, the molybdenum salt is sodium molybdate or ammonium molybdate, and the cerium salt is cerium nitrate or cerium sulfate.

4. The method for preparing the Ce-NiMo / NF catalyst according to claim 1, characterized by, The temperature rising rate during the hydrothermal reaction is 2-3℃ / min; the temperature rising rate during the reduction reaction is 4-5℃ / min.

5. The method of claim 1, wherein the Ce-NiMo / NF catalyst is prepared by the steps of: The temperature of the hydrothermal reaction is 150℃, and the time is 6 h.

6. The method of claim 1, wherein the Ce-NiMo / NF catalyst is prepared by the steps of: The temperature of the reduction reaction is 550℃, and the time is 2 h.

7. A Ce-NiMo / NF catalyst characterized in that, The catalyst is prepared by the preparation method of any one of claims 1-6.

8. Application of the Ce-NiMo / NF catalyst of claim 7 in the field of furfural electro-oxidation.

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