A low noble metal loading electrocatalyst, its preparation method and application

Abstract

The application relates to a low noble metal loading electrocatalyst and a preparation method and application thereof. The low noble metal loading electrocatalyst comprises a self-supporting carrier, Co3O4 nanosheets loaded on the self-supporting carrier and array-distributed, and noble metal monomers loaded on the Co3O4 nanosheets; wherein the noble metal monomers comprise at least one of Pt monomers, Pd monomers and Ru monomers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic nanomaterials, and particularly relates to a low noble metal loading electrocatalyst for glycerol small molecule value-added electrooxidation in a neutral medium and a preparation method thereof. BACKGROUND

[0002] Glycerol is a low-value byproduct (about 10 wt.% of the total product) in the production of the biodiesel industry, and glycerol is also listed as one of the top ten biomass-derived platform molecules by the US Department of Energy, which is of great significance for the conversion of glycerol into high-value chemicals. Compared with traditional glycerol oxidation technology, under the driving of green power such as solar energy and wind energy, electrocatalytic glycerol oxidation reaction (GOR) for producing high-value chemicals has the advantages of environmental friendliness, sustainability and high efficiency. GOR can produce various high-value products such as glycerol aldehyde, dihydroxyacetone, glyceric acid, glycolic acid and formic acid. Therefore, it is of great significance to develop an electrocatalyst for glycerol oxidation reaction with high activity and high product selectivity.

[0003] Among the many oxidation products, glycerol aldehyde (a C3 aldehyde compound) with high added value has great application prospect, and it is of great research value to prepare C3 aldehyde compounds with high selectivity. However, the commonly used alkaline medium (such as 1M KOH) seriously hinders the synthesis of aldehyde products, because aldehyde is converted into gem-diol through hydration in alkaline medium, and is further oxidized to obtain carboxylic acid products. On the other hand, aldehyde may undergo side reactions such as aldol condensation and dimerization in alkaline medium, and cannot exist stably. In addition, strong alkali can also corrode the device. Therefore, in order to avoid these problems, a near-neutral medium is selected as the reaction electrolyte. However, under neutral conditions, there is a lack of strong nucleophile OH - , and the active center is insufficient, resulting in slow reaction kinetics of glycerol in the neutral medium and low selectivity of high-value C3 products.

[0004] Therefore, it is of great significance to develop a GOR catalyst capable of realizing high activity and high product selectivity in a near-neutral medium. SUMMARY

[0005] In view of the above technical problems, the application provides a low noble metal loading GOR electrocatalyst capable of realizing high activity and high C3 product selectivity in a near-neutral medium, and a preparation method and application thereof.

[0006] In a first aspect, the application provides a low noble metal loading electrocatalyst, which comprises: a self-supporting carrier, Co3O4 nanosheets arrayed and loaded on the self-supporting carrier, and noble metal monomers loaded on the Co3O4 nanosheets.

[0007] The noble metal monatomic atom includes at least one of a Pt monatomic atom, a Pd monatomic atom and a Ru monatomic atom.

[0008] Preferably, the self-supporting carrier is at least one of foamed nickel, foamed copper and foamed cobalt, and preferably is foamed nickel.

[0009] The Co3O4 nanosheet has a diameter of 400-800 nm, preferably 500-800 nm, and more preferably 500 nm, and a thickness of 5-30 nm.

[0010] Preferably, the self-supporting carrier has a loading amount of the Co3O4 nanosheet on the surface of 4-20 mg / cm2. 2 The mass ratio of the noble metal monatomic atom to the Co3O4 nanosheet is 1:(50-200).

[0011] In a second aspect, the present application provides a preparation method of the above-mentioned low-noble-metal-loading electrocatalyst, and the preparation method comprises the following steps:

[0012] (1) mixing a solution containing a cobalt source, a noble metal source and a precipitant to obtain a precursor solution;

[0013] (2) placing a self-supporting carrier into the above-mentioned precursor solution to make the cobalt source and the noble metal source nucleate and grow, and then performing cleaning and drying after the growth to obtain a noble metal-cobalt hydroxide nanosheet array loaded on the self-supporting carrier;

[0014] (3) performing heat treatment on the above-mentioned noble metal-cobalt hydroxide nanosheet array loaded on the self-supporting carrier in a protective atmosphere to obtain the low-noble-metal-loading electrocatalyst.

[0015] Preferably, in step (1), the cobalt source is at least one of cobalt nitrate hexahydrate, cobalt sulfate heptahydrate and cobalt chloride hexahydrate, and preferably is cobalt nitrate hexahydrate.

[0016] The noble metal source includes at least one of a platinum source, a palladium source and a ruthenium source; wherein the platinum source is at least one of chloroplatinic acid hexahydrate, potassium chloroplatinate, ammonium hexachloroplatinate and platinum acetylacetonate; the palladium source is at least one of palladium dichloride, palladium nitrate dihydrate and palladium acetylacetonate; and the ruthenium source is at least one of ruthenium trichloride hydrate, ruthenium dioxide and ruthenium acetylacetonate, and preferably is ruthenium trichloride hydrate.

[0017] The precipitant is at least one of urea, hexamethylenetetramine and ammonium fluoride, and preferably is hexamethylenetetramine.

[0018] Preferably, in step (1), the mass ratio of the cobalt source to the noble metal source is 50-290:1, and the molar ratio of the cobalt source to the precipitant is 1:1-5.

[0019] Preferably, in step (2), 0.1-4 cm3 of the self-supporting carrier is used per 1 mmol of the cobalt source. 2 Preferably, in step (2), 0.1-4 cm3 of the self-supporting carrier is used per 1 mmol of the cobalt source.

[0020] Preferably, in step (2), the nucleation and growth process is incubation at 80-150℃ for 4-16 hours.

[0021] Preferably, in step (3), the protective atmosphere is air, the temperature of the heat treatment is 300-550℃, preferably 350-550℃, and the time of the heat treatment is 1-4 hours.

[0022] In a third aspect, the application provides a use of the above-mentioned low-noble-metal-loading electrocatalyst in the electrocatalytic value-added oxidation of glycerol under near-neutral conditions.

[0023] Advantages

[0024] (1) The Ru-Co3O4 / NF catalyst provided by the application continuously generates CoOOH active species in situ in GOR, improves the kinetics of GOR, regulates the adsorption mode of glycerol, realizes a primary alcohol oxidation path of glycerol, and achieves a C3 product selectivity of >90%;

[0025] (2) The application successfully prepares a noble-metal-single-atom-loaded cobalt trioxide tetraoxide nanometer array using a hydrothermal method, increases the specific surface area while exposing active sites, realizes rapid mass transfer, and thus obtains a large current density;

[0026] (3) The preparation method described in the application reduces the content of noble metals (the amount of Ru can be 0.5-2 wt.%) and improves the dispersion of noble metals (in the form of single atoms) to prepare a low-noble-metal-content catalyst with high utilization rate to reduce costs, and the preparation conditions are mild and simple, having high economic benefits and practical value. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 SEM images of Co3O4 / NF prepared for Comparative Example 1 (a), 5-Ru-Co3O4 / NF prepared for Example 1 (b), RuO x / NF prepared for Comparative Example 2 (c), and NF prepared for Comparative Example 3 (d);

[0028] Figure 2 XRD images of Co3O4 / NF prepared for Comparative Example 1 (a) and 5-Ru-Co3O4 / NF prepared for Example 1 (b);

[0029] Figure 3TEM images of Co3O4 / NF prepared for Comparative Example 1 (a), selected area TEM images (b), TEM images of 5-Ru-Co3O4 / NF prepared in Example 1 (c), selected area TEM images (d);

[0030] Figure 4 Raman images of Co3O4 / NF prepared for Comparative Example 1 (a), Raman images of 5-Ru-Co3O4 / NF prepared in Example 1 (b);

[0031] Figure 5 LSV (linear sweep voltammetry) plots of 5-Ru-Co3O4 / NF prepared in Example 1 with and without glycerol (a) and LSV plots of Co3O4 / NF prepared for Comparative Example 1, RuO x / NF prepared for Comparative Example 2, Ru / Co3O4-NF prepared for Comparative Example 4 and 5-Ru-Co3O4 / NF prepared in Example 1 with glycerol (b), in (a) each curve from top to bottom is with glycerol, without glycerol, in (b) each curve from top to bottom is Example 1, Comparative Example 4, Comparative Example 1, Comparative Example 2;

[0032] Figure 6 Tafel slope plots of Co3O4 / NF prepared for Comparative Example 1, 5-Ru-Co3O4 / NF prepared in Example 1 and RuO x / NF prepared for Comparative Example 2 (a), ECSA (electrochemical active area) plots of Co3O4 / NF prepared for Comparative Example 1, 5-Ru-Co3O4 / NF prepared in Example 1 (b) and Nyquist plots of EIS (electrochemical impedance spectroscopy) of Co3O4 / NF prepared for Comparative Example 1, 5-Ru-Co3O4 / NF prepared in Example 1 (c);

[0033] Figure 7 Product selectivity plots of Co3O4 / NF prepared for Comparative Example 1 (a), C3 product selectivity and C3 product yield plots (b), in (a) each bar from top to bottom is glyceric acid, glycerol aldehyde, dihydroxyacetone, in (b) left y-axis corresponds to C3 product selectivity, right y-axis corresponds to C3 product yield;

[0034] Figure 8 Product selectivity plots of 5-Ru-Co3O4 / NF prepared in Example 1 (a), C3 product selectivity and C3 product yield plots (b), in (a) each bar from top to bottom is glyceric acid, glycerol aldehyde, dihydroxyacetone, in (b) left y-axis corresponds to C3 product selectivity, right y-axis corresponds to C3 product yield;

[0035] Figure 9CP (chronopotentiometry) curve of 5-Ru-Co3O4 / NF prepared for Example 1;

[0036] Figure 10 Co3O4 / NF prepared for Comparative Example 1, RuO x LSV curves of Co3O4 / NF prepared for Comparative Example 1, RuO DETAILED DESCRIPTION

[0037] The present application is further illustrated by the following examples, which should not be construed as limiting the present application.

[0038] Firstly, the present application provides a low noble metal loading electrocatalyst. The low noble metal loading electrocatalyst can include a self-supporting carrier, Co3O4 nanosheets loaded on the self-supporting carrier and arrayed, and noble metal monomers loaded on the Co3O4 nanosheets; preferably, the noble metal monomers can include at least one of Pt monomers, Pd monomers, and Ru monomers.

[0039] In some embodiments, the self-supporting carrier can be at least one of nickel foam (NF), copper foam, and cobalt foam, preferably nickel foam.

[0040] In some embodiments, the Co3O4 nanosheets can have a diameter of 400-800 nm, preferably 500-800 nm, and more preferably 500 nm, and a thickness of 5-30 nm. The present application has a relatively larger diameter, thinner nanosheet morphology, more active centers, more abundant edge active sites, and fast interface charge transfer capacity, which is conducive to improving the overall catalytic performance.

[0041] In some embodiments, the loading amount of the Co3O4 nanosheets on the surface of the self-supporting carrier can be 4-20 mg / cm 2 .

[0042] In some embodiments, the mass ratio of the noble metal single atom and the Co3O4 nanosheet can be 1:(50-200). In this way, the synergy of Co3O4 and noble metal single atoms can be fully exerted. When the noble metal loading is too high, the noble metal is prone to agglomerate into nanoparticles or clusters, which can cause excessive adsorption of glycerol, and is not conducive to the GOR reaction. By reducing the content of noble metal to improve the dispersion of noble metal (in the form of single atom) to prepare a low noble metal content catalyst with high utilization rate, the cost can be reduced, and the catalyst has high economic benefit and practical value. Moreover, such distribution mode promotes the full exposure of active sites, thereby promoting the reaction to occur rapidly and efficiently.

[0043] The low noble metal loading electrocatalyst provided by the present application is beneficial to the adsorption of OH - and accelerates the oxidation reaction of glycerol. In addition, the noble metal has the best adsorption capacity for oxygen-containing intermediates, effectively adjusts the adsorption configuration of glycerol, and achieves the effect of high selectivity of C3 product.

[0044] Hereinafter, the preparation method of the low noble metal loading electrocatalyst provided by the present application is exemplarily described. The preparation method can include the following steps:

[0045] (1) mixing a solution containing a cobalt source, a noble metal source and a precipitant to obtain a precursor solution;

[0046] (2) placing a self-supporting carrier into the precursor solution to make the cobalt source and the noble metal source nucleate and grow, and after the growth is completed, washing and drying are performed to obtain a noble metal-cobalt hydroxide nanosheet array loaded on the self-supporting carrier;

[0047] (3) heat treating the noble metal-cobalt hydroxide nanosheet array loaded on the self-supporting carrier in a protective atmosphere to obtain the low noble metal loading electrocatalyst.

[0048] In some embodiments, in step (1), the cobalt source can be at least one of cobalt nitrate hexahydrate, cobalt sulfate heptahydrate and cobalt chloride hexahydrate, and preferably is cobalt nitrate hexahydrate.

[0049] In some embodiments, in step (1), the noble metal source can include at least one of a platinum source, a palladium source and a ruthenium source; wherein: the platinum source can be at least one of chloroplatinic acid hexahydrate, potassium chloroplatinate, ammonium hexachloroplatinate and platinum acetylacetonate; the palladium source can be at least one of palladium dichloride, palladium nitrate dihydrate and palladium acetylacetonate; and the ruthenium source can be at least one of ruthenium trichloride hydrate, ruthenium dioxide and ruthenium acetylacetonate, and preferably is ruthenium trichloride hydrate.

[0050] In some embodiments, in step (1), the precipitant can be at least one of urea, hexamethylenetetramine, ammonium fluoride, and preferably hexamethylenetetramine. The precipitant can play the role of a nucleating agent, the cobalt source can react with the precipitant to generate an alkaline environment, and the rate of nucleation and growth can be increased.

[0051] In some embodiments, in step (1), the mass ratio of the cobalt source to the noble metal source can be 50-290: 1, and preferably 50-200: 1; and the molar ratio of the cobalt source to the precipitant can be 1: 1-5. By controlling the mass ratio of the cobalt source to the noble metal source in the above range, the noble metal can be more easily controlled to be in the form of a single atom during subsequent heat treatment; and by controlling the molar ratio of the cobalt source to the precipitant in the above range, a more uniform nanosheet array can be obtained.

[0052] In some embodiments, in step (1), 5-30 mL of solvent can be used per 1 mmol of cobalt source; and preferably, the solvent can be at least one of methanol, ethanol, and deionized water, and preferably deionized water.

[0053] In some embodiments, in step (1), the solution can be uniformly mixed by ultrasonic and stirring; and preferably, the mixed solution is ultrasonically treated for 3-10 minutes and stirred at room temperature for 0.1-1 hour to mix uniformly. As an example, raw materials are prepared according to a molar ratio of cobalt nitrate to hexamethylenetetramine of 1:(1-5) and a mass ratio of the cobalt source to the ruthenium source of 50-200: 1, 5-30 mL of deionized water is added per 1 mmol of cobalt nitrate, ultrasonic treatment is performed for 3-10 minutes, and stirring is performed at room temperature for 0.1-1 hour to mix uniformly to obtain a precursor solution.

[0054] In the preparation method provided by the present application, the solutions of the cobalt source, the noble metal source, and the precipitant are directly mixed to obtain a precursor solution. Compared with the traditional synthesis method, the preparation process is simple, efficient, and convenient. By directly mixing the solutions of the cobalt source, the noble metal source, and the precipitant, the noble metal single atom can be doped into the crystal lattice of the Co-based oxide, different sites for the noble metal single atom to be doped can be selectively controlled, the atomic utilization rate of the single atom can be improved, and thus the cost can be effectively reduced. In addition, directly mixing the raw materials can avoid a complicated synthesis process on the one hand, and can avoid agglomeration of the noble metal source during the subsequent synthesis process on the other hand, so that unnecessary nanoparticles or clusters are not generated, and thus the synthesis of the noble metal single atom can be maximized.

[0055] In some embodiments, in step (2), 0.1-4 cm 2 of the self-supporting carrier can be used per 1 mmol of the cobalt source.

[0056] In some embodiments, in step (2), the nucleation and growth process can be incubation at 80-150 DEG C for 4-16 hours. In this way, the cobalt source can be uniformly nucleated to form a nanosheet array, and uniform doping of the noble metal source can be promoted. If the hydrothermal temperature is too low or the time is too short, the nanosheet array cannot be formed; if the temperature is too high or the time is too long, uniform doping of the low-loading noble metal monolayer cannot be promoted.

[0057] In some embodiments, in step (2), the drying temperature can be 20-80 DEG C.

[0058] In some embodiments, in step (3), the protective atmosphere can be air, the heat treatment temperature can be 300-550 DEG C, preferably 350-550 DEG C, and the heat treatment time can be 1-4 hours. If the heat treatment temperature is too low, the nitrogen source contained in the precursor cannot be completely removed; if the heat treatment temperature is too high, the morphology can be easily changed.

[0059] The catalyst provided by the present application can achieve a current density of 10 mAcm-2 at 1.16 V vs. RHE and a current density of 200 mAcm-2 at 1.84 V vs. RHE under near-neutral conditions (such as pH = 8). -2 -2 Due to the difference in electronegativity between Co and the noble metal, the Co with small electronegativity transfers electrons to the noble metal, which is conducive to the adsorption of OH - by the Co with more positive charges, so that the hydroxyl group is oxidized to form a hydroxyl oxide active species, thereby accelerating the oxidation reaction kinetics of glycerol. Therefore, the GOR activity of the catalyst is enhanced. In addition, the noble metal has the best adsorption capacity for oxygen-containing intermediates, which effectively adjusts the adsorption configuration of glycerol, thereby achieving a C3 product selectivity of > 90% in a wide potential range.

[0060] The nanocatalyst provided by the present application has an orderly arranged nanosheet array morphology, and can have high GOR activity and high C3 product selectivity under near-neutral conditions, and can be stably operated for more than 100 h during the it test. In addition, the preparation method provided by the present application has mild conditions and is easy to operate. The present application solves the problems of slow reaction kinetics of glycerol in neutral medium and low selectivity of high-value-added C3 products due to the lack of strong nucleophile OH - and active centers under near-neutral conditions.

[0061] The nanocatalyst of the present application has excellent GOR activity, high C3 product selectivity, and good GOR electrocatalytic stability under near-neutral conditions, and can be applied to electrocatalytic glycerol value-added oxidation under near-neutral conditions.

[0062] ​The following examples are further illustrated to explain the present application in detail. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as a limitation to the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application are within the scope of protection of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can make appropriate selection within the range according to the description herein, and are not limited to the specific values in the following examples. If not specifically indicated, the technical means used in the examples are the conventional means known to those skilled in the art.

[0063] Unless otherwise specified:

[0064] The electrocatalytic activity was tested by three-electrode method using Shanghai Chenhua CHI 760E electrochemical workstation; the reference electrode was Ag / AgCl electrode, the counter electrode was carbon rod, and the scanning voltage method was in the range of -0.1-1.4V (vs. Ag / AgCl); the electrocatalytic activity test was carried out by electrocatalytic glycerol oxidation in 0.1M KHCO3 aqueous solution with glycerol in near neutral environment.

[0065] Example 1

[0066] The preparation method of the low noble metal loading electrocatalyst provided in the present embodiment comprises the following steps:

[0067] At room temperature, 0.87g (3mmol) of cobalt nitrate hexahydrate, 0.005g of RuCl3·H2O and 6mmol of methenamine were added to 80mL of deionized water, ultrasonic for 5 minutes and stirred at room temperature for 1h to obtain a uniform mixed solution;

[0068] The obtained solution was placed in a self-supporting body of 10cm 2 area of foam nickel (NF), and the self-supporting body was taken out, washed with water, and vacuum dried to obtain a Ru-Co(OH) x / NF precursor in nanoarray form;

[0069] The Ru-Co(OH) 2 / NF precursor with an area of 2cm x was placed in a crucible and calcined at 400℃ for 3h in a tube furnace, and then taken out after cooling to room temperature to obtain a Ru-Co3O4 / NF nanocatalyst material (marked as 5-Ru-Co3O4 / NF) with nanoarray form.

[0070] Example 2

[0071] The preparation method of the low noble metal loading electrocatalyst provided in this embodiment refers to embodiment 1, and the main difference is that 0.007 g of RuCl3·H2O is added to the raw material, and the prepared Ru-Co3O4 / NF nanocatalyst material with nano array shape is marked as 7-Ru-Co3O4 / NF.

[0072] Example 3

[0073] The preparation method of the low noble metal loading electrocatalyst provided in this embodiment refers to embodiment 1, and the main difference is that 0.009 g of RuCl3·H2O is added to the raw material, and the prepared Ru-Co3O4 / NF nanocatalyst material with nano array shape is marked as 9-Ru-Co3O4 / NF.

[0074] Example 4

[0075] The preparation method of the low noble metal loading electrocatalyst provided in this embodiment refers to embodiment 1, and the main difference is that 0.003 g of RuCl3·H2O is added to the raw material, and the prepared Ru-Co3O4 / NF nanocatalyst material with nano array shape is marked as 3-Ru-Co3O4 / NF.

[0076] Comparative Example 1

[0077] The preparation method of the catalyst material provided in this comparative example refers to embodiment 1, and the main difference is that RuCl3·H2O is not added to the raw material, and finally the Co3O4 / NF nanocatalyst material (marked as Co3O4 / NF) is obtained.

[0078] Comparative Example 2

[0079] The preparation method of the catalyst material provided in this comparative example refers to embodiment 1, and the main difference is that cobalt nitrate is not added to the raw material, and finally the RuO x / NF nanocatalyst material (marked as RuO x / NF) is obtained.

[0080] Comparative Example 3

[0081] The preparation method of the catalyst material provided in this comparative example refers to embodiment 1, and only the nickel foam is pretreated to obtain the NF material.

[0082] Comparative Example 4

[0083] The preparation method of the catalyst material provided by the present comparative example refers to Example 1, and the main difference is that: first, the noble metal source RuCl3·H2O is not added in the raw material, and the Co(OH)2 / NF nanocatalyst precursor material is obtained first; then, referring to Example 1, only RuCl3·H2O is added in the raw material, and no cobalt nitrate is added, that is, the cobalt source and the noble metal source are nucleated and grown in sequence, and the prepared catalyst material is marked as Ru / Co3O4-NF.

[0084] Figure 1 The SEM image of Co3O4 / NF prepared for Comparative Example 1 (a), the SEM image of 5-Ru-Co3O4 / NF prepared for Example 1 (b), the SEM image of RuO x / NF prepared for Comparative Example 2 (c), and the SEM image of NF prepared for Comparative Example 3 (d). As can be seen from the figure, the Co3O4 / NF prepared for Comparative Example 1 has a micro-morphology of nanosheet array; the 5-Ru-Co3O4 / NF prepared for Example 1 has a micro-morphology of nanosheet array, and the addition of Ru does not change the morphology of Co3O4; the RuO x / NF prepared for Comparative Example 2 does not have a micro-morphology of nanosheet array, but rather some loose hollow structures; the NF prepared for Comparative Example 3 has a smooth and flat surface.

[0085] Figure 2 The XRD image of Co3O4 / NF prepared for Comparative Example 1 (a), and the XRD image of 5-Ru-Co3O4 / NF prepared for Example 1 (b). According to the XRD image, it can be seen that the crystal form of the Co3O4 / NF prepared for Comparative Example 1 has a PDF card number of 42-1467 in the Joint Committee on Powder Diffraction (JCPDS), and the Ru-Co3O4 / NF prepared for Example 1 maintains the crystal phase structure of spinel Co3O4.

[0086] Figure 3 The TEM image of Co3O4 / NF prepared for Comparative Example 1 (a), the selected area TEM image (b), the TEM image of 5-Ru-Co3O4 / NF prepared for Example 1 (c), and the selected area TEM image (d). According to the selected area TEM, it can be determined that the main exposed crystal face of the Co3O4 / NF nanosheet in photograph (a) is the (311) crystal face, and according to the selected area TEM, it can be determined that the main exposed crystal face of the 5-Ru-Co3O4 / NF nanosheet in photograph (d) is the (311) crystal face, and Ru remains in the form of a single atom uniformly dispersed on Co3O4.

[0087] Figure 4Raman spectra (a) for Co3O4 / NF prepared in Comparative Example 1 and (b) for 5-Ru-Co3O4 / NF prepared in Example 1. As can be seen from the Raman spectra, the Raman spectrum of Co3O4 / NF prepared in Comparative Example 1 is in the range of 100-800 cm⁻¹. -1 Five characteristic peaks were observed within the range, corresponding to the F of spinel Co3O4, respectively. 2g 1 E g F 2g 2 F 2g 3 and A 1g Vibrational model; Raman spectra of Co3O4 / NF prepared in Example 1 in the range of 100-800 cm⁻¹ -1 Five characteristic peaks were observed within the range, corresponding to the F of spinel Co3O4, respectively. 2g 1 E g F 2g 2 F 2g 3 and A 1g Vibration model.

[0088] Figure 5 The LSV (linear voltammetry) curves of 5-Ru-Co3O4 / NF prepared in Example 1 with and without glycerol are shown in Figure (a) and the curves of Co3O4 / NF prepared in Comparative Example 1 and RuO2 prepared in Comparative Example 2 are also shown. x The LSV curves (b) of 5-Ru-Co3O4 / NF prepared in Example 1, Comparative Example 4, and Comparative Example 5-Ru-Co3O4 / NF are shown in Figure 1. In Figure 1, the curves from top to bottom represent those with and without glycerol addition, while in Figure 2, the curves from top to bottom represent those of Example 1, Comparative Example 4, Comparative Example 1, and Comparative Example 2. It can be seen from the figures that the current density of Co3O4 / NF prepared in Comparative Example 1 is 100 mA cm⁻¹ under near-neutral conditions. -2 The voltage for GOR electrocatalysis was 1.79 V vs. RHE; the current density of Ru / Co3O4-NF prepared in Comparative Example 4 was 100 mA cm⁻¹ under near-neutral conditions. -2 The electrocatalytic voltage of GOR was 1.74 V vs. RHE; Comparative Example 2 prepared RuO x / NF has a current density of 10 mA cm⁻¹ under near-neutral conditions. -2 The voltage of the GOR electrocatalysis at that time was 1.78V vs. RHE, far less than 100mAcm. -2, which is the worst material in the performance of the implementation case; after adding glycerol, the 5-Ru-Co3O4 / NF prepared in Example 1 moves 246 mV at a current density of 10 mA cm -2 , which means that the glycerol oxidation reaction is more favorable in thermodynamics, and the voltage of GOR electrocatalysis at a current density of 100 mA cm -2 -2 in near-neutral conditions is 1.62 V vs. RHE, which is the best in the implementation case.

[0089] Figure 6 The Tafel slope (a) of Co3O4 / NF prepared in Comparative Example 1, 5-Ru-Co3O4 / NF prepared in Example 1, and RuO x / NF prepared in Comparative Example 2, the ECSA (b) of Co3O4 / NF prepared in Comparative Example 1 and 5-Ru-Co3O4 / NF prepared in Example 1, and the Nyquist plot (c) of EIS of Co3O4 / NF prepared in Comparative Example 1, 5-Ru-Co3O4 / NF prepared in Example 1. As can be seen from the figure, the Tafel slope of GOR electrocatalysis in near-neutral conditions of Co3O4 / NF prepared in Comparative Example 1 is 61.9 mV dec -1 , the ECSA of GOR electrocatalysis in near-neutral conditions is 6.44 mF cm -1 , and the interfacial transfer resistance Rct of GOR electrocatalysis in near-neutral conditions is 5 Ω; the Tafel slope of GOR electrocatalysis in near-neutral conditions of 5-Ru-Co3O4 / NF prepared in Example 1 is 33.9 mV dec -1 , the ECSA of GOR electrocatalysis in near-neutral conditions is 12.25 mF cm -1 , and the interfacial transfer resistance Rct of GOR electrocatalysis in near-neutral conditions is 2.5 Ω; the Tafel slope of GOR electrocatalysis in near-neutral conditions of RuO x / NF prepared in Comparative Example 2 is 193.1 mV dec -1 .

[0090] Figure 7Product selectivity graph (a) of Co3O4 / NF prepared for Comparative Example 1, C3 product selectivity and C3 product yield graph (b), each column in (a) from top to bottom is glyceric acid, glycolaldehyde, dihydroxyacetone, left y-axis in (b) corresponds to C3 product selectivity, right y-axis corresponds to C3 product yield. As can be seen from the graph, Co3O4 / NF prepared for Comparative Example 1 has the highest selectivity for dihydroxyacetone product in a wide potential range, which can be maintained at about 50%, the overall C3 product selectivity in a wide potential range is > 80%, the overall C3 product yield in a wide potential range shows an upward trend, and reaches the highest at 1.7 V vs. RHE, ~ 0.2 mmol cm -2 h -1 .

[0091] Figure 8 Product selectivity graph (a) of 5-Ru-Co3O4 / NF prepared for Example 1, C3 product selectivity and C3 product yield graph (b), each column in (a) from top to bottom is glyceric acid, glycolaldehyde, dihydroxyacetone, left y-axis in (b) corresponds to C3 product selectivity, right y-axis corresponds to C3 product yield. As can be seen from the graph, 5-Ru-Co3O4 / NF prepared for Example 1 has the highest selectivity for glycolaldehyde product in a wide potential range, which is maintained between 55-60%, the overall C3 product selectivity in a wide potential range is > 90%, the overall C3 product yield in a wide potential range shows an upward trend, and reaches the highest at 1.7 V vs. RHE, ~ 0.41 mmol cm -2 h -1 .

[0092] Figure 9 CP (chronopotentiometry) curve graph of 5-Ru-Co3O4 / NF prepared for Example 1. As can be seen from the graph, it can be stably operated at a current density of 10 mA cm -2 for more than 100 h, which proves its excellent stability.

[0093] Figure 10 LSV curve graph of Co3O4 / NF prepared for Comparative Example 1, RuO x 2 prepared for Comparative Example 2, 5-Ru-Co3O4 / NF prepared for Example 1, 7-Ru-Co3O4 / NF prepared for Example 2, 9-Ru-Co3O4 / NF prepared for Example 3, and 3-Ru-Co3O4 / NF prepared for Example 4 in the presence of glycerol; wherein each curve from top to bottom is Example 1, Example 2, Example 4, Comparative Example 1, Example 3, and Comparative Example 2. As can be seen from the graph, Co3O4 / NF prepared for Comparative Example 1 has a current density of 100 mA cm -2The GOR electrocatalysis voltage was 1.79 V vs. RHE at the time; the 5-Ru-Co304 / NF prepared in Example 1 had a current density of 100 mA cm -2 The GOR electrocatalysis voltage was 1.62 V vs. RHE at the time; the sample in Example 2 had a current density of 10 mA cm -2 The GOR electrocatalysis voltage was 1.32 V vs. RHE at the time; the sample in Example 3 had a current density of 10 mA cm -2 The GOR electrocatalysis voltage was 1.47 V vs. RHE at the time; the sample in Example 4 had a current density of 10 mA cm -2 The GOR electrocatalysis voltage was 1.39 V vs. RHE at the time; the RuO x / NF prepared in Comparative Example 2 had a current density of 10 mA cm -2 The GOR electrocatalysis voltage was 1.78 V vs. RHE at the time, which was the worst performing material among all cases.

[0094] Although the present application has been described in detail through the preferred embodiments above, it should be appreciated that the above description should not be considered as limiting the present application. Various modifications and substitutions will be apparent to those skilled in the art after reading the above description. Therefore, the scope of the present application should be defined by the appended claims.

Claims

1. Use of a low noble metal loading electrocatalyst in the electrocatalytic valorized oxidation of glycerol under near-neutral conditions, characterized in that, The low noble metal loading electrocatalyst comprises: a self-supporting carrier, Co3O4 nanosheets arrayed and loaded on the self-supporting carrier, and noble metal monomers loaded on the Co3O4 nanosheets. The self-supporting carrier is foamed nickel, foamed copper or foamed cobalt, the noble metal single atom is a Ru single atom, the loading amount of the Co3O4 nanosheet on the surface of the self-supporting carrier is 4-20 mg / cm2, and the mass ratio of the noble metal single atom to the Co3O4 nanosheet is 1:(50-200). 2 , the self-supporting carrier is foamed nickel, foamed copper or foamed cobalt, the noble metal single atom is a Ru single atom, the loading amount of the Co3O4 nanosheet on the surface of the self-supporting carrier is 4-20 mg / cm2, and the mass ratio of the noble metal single atom to the Co3O4 nanosheet is 1:(50-200).

2. Use of the low noble metal loading electrocatalyst according to claim 1 for the electrocatalytic valorized oxidation of glycerol under near-neutral conditions, characterized in that, The Co3O4 nanosheets have a diameter of 400-800 nm and a thickness of 5-30 nm.

3. Use of the low noble metal loading electrocatalyst according to claim 1 for the electrocatalytic valorized oxidation of glycerol at near neutral conditions, characterized in that, The preparation method of the low noble metal loading electrocatalyst comprises the following steps: (1) mixing a solution containing a cobalt source, a noble metal source and a precipitant to obtain a precursor solution; (2) placing a self-supporting carrier into the precursor solution to make the cobalt source and the noble metal source nucleate and grow, and then performing cleaning and drying to obtain noble metal-cobalt hydroxide nanosheet arrays loaded on the self-supporting carrier; (3) performing heat treatment on the noble metal-cobalt hydroxide nanosheet arrays loaded on the self-supporting carrier in a protective atmosphere to obtain the low noble metal loading electrocatalyst.

4. Use according to claim 3, characterized in that, In step (1), the cobalt source is at least one of cobalt nitrate hexahydrate, cobalt sulfate heptahydrate and cobalt chloride hexahydrate; the noble metal source is a ruthenium source; wherein the ruthenium source is at least one of ruthenium trichloride hydrate, ruthenium dioxide and ruthenium acetylacetonate; and the precipitant is at least one of urea, hexamethylenetetramine and ammonium fluoride.

5. Use according to claim 3, characterized in that, In step (1), the mass ratio of the cobalt source to the noble metal source is 50-290:1, and the molar ratio of the cobalt source to the precipitant is 1:1-5.

6. Use according to claim 3, characterized in that, In step (2), 0.1 to 4 cm of the self-supporting carrier was used per 1 mmol of the cobalt source. 2 of the self-supporting carrier.

7. Use according to claim 3, characterized in that, In step (2), the nucleation and growth process is 80-150℃ for 4-16 hours.

8. Use according to claim 3, characterized in that, In step (3), the protective atmosphere is air, the heat treatment temperature is 300-550℃, and the heat treatment time is 1-4 hours.

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