A method for preparing a carrier-metal strong interaction catalyst for a direct formate fuel cell anode

Abstract

A method for preparing a carrier-metal strong interaction catalyst for a direct formate fuel cell anode belongs to the field of liquid fuel cell anode catalysts. The present invention ultrasonically disperses ruthenium dioxide in deionized water, mixes it with a chloropalladic acid solution, heats and stirs it, washes it, vacuum dries it, and calcines it in a tube furnace under an argon atmosphere. After natural cooling, the final catalyst Pd / RuO2 is obtained. The carrier-supported metal catalyst prepared by this method utilizes the strong interaction between ruthenium dioxide (carrier) and palladium (metal), effectively promotes the desorption of intermediates and improves the catalytic activity of formate electrooxidation.

Description

Technical Field

[0001] The invention belongs to the field of direct liquid fuel cell anode catalysts, and specifically discloses a method for preparing a carrier-metal strong interaction catalyst for a direct formate fuel cell anode. Background Art

[0002] Alkaline anion exchange membrane fuel cells have attracted the attention of researchers because they reduce dependence on fossil fuels. Among them, direct formate fuel cells can directly convert chemical energy in formate into electrical energy, and are safe and have high energy conversion efficiency. However, the development of direct formate fuel cells is facing the bottleneck of poor anode kinetics. The design and preparation of formate electrocatalysts with high catalytic performance and low cost are crucial for the widespread application of direct formate fuel cells.

[0003] Studies have shown that the oxidation of formate over palladium-based catalysts produces a strongly adsorbed intermediate (H ad ), H ad It will occupy the palladium active sites, hinder the further adsorption of reactants, and reduce the electrocatalytic performance of formate. Therefore, it is necessary to modify the palladium-based catalyst to solve the problem of difficult desorption of intermediates in the formate oxidation process in order to improve the electrooxidation activity of formate.

[0004] In the present invention, we modify the palladium-based catalyst by loading palladium with ruthenium dioxide. The active oxygen species contained in the ruthenium dioxide will react with the H on the palladium. ad The strong interaction between ruthenium dioxide (support) and palladium (metal) solves the problem of H in the electrooxidation of formate. ad The problem of difficult desorption. The preparation method of the Pd / RuO2 anode catalyst we proposed is simple and has a low content of precious metals, which is conducive to its commercial application while saving costs. Summary of the invention

[0005] In view of the defects of commercial palladium-carbon catalysts in catalyzing the electro-oxidation of formate, the present invention aims to provide a simple and efficient method for preparing a formate electrocatalyst, which can effectively promote the removal of intermediates in the reaction process and improve its activity. In order to solve the above technical problems, the present invention provides a carrier-metal strong interaction catalyst for the anode of a direct formate fuel cell, characterized in that palladium is loaded on ruthenium dioxide, and the loading amount of palladium is 2wt%-10wt%, and further 2wt%-7wt%.

[0006] The preparation method of the above-mentioned carrier-metal strong interaction catalyst comprises the following steps:

[0007] (1) Preparation of chloropalladium acid solution;

[0008] (2) ultrasonically dispersing RuO2 in deionized water;

[0009] (3) adding the chloropalladium acid solution prepared in (1) dropwise into (2), and stirring the mixed solution at 70° C. for 5 h; washing the collected samples with water and ethanol, and drying them in vacuum;

[0010] (4) The sample of step (3) was placed in a tubular furnace and calcined at 400°C for 2 h under an argon atmosphere, and then naturally cooled to obtain the product Pd / RuO2.

[0011] The preparation of the chloropalladic acid solution is as follows: palladium chloride is dispersed in water, and then concentrated hydrochloric acid is added, wherein for every 4-8 mg of palladium chloride, 2-4 ml of deionized water and 4-8 μl of concentrated hydrochloric acid are corresponding. The stirring is magnetic stirring to form a uniform dispersion system. In step (2), every 50 mg of RuO2 is corresponding to 70-100 mL of deionized water.

[0012] Step (4) of the present invention further improves the performance of the catalyst.

[0013] The obtained Pd / RuO2 is used in direct formate fuel cell anodes and to overcome hydrogen poisoning.

[0014] Further preference is given to: electrolysis in 1M KOH+1M HCOOK solution; using a three-electrode system: counter electrode - platinum wire, reference electrode - Hg / HgO electrode, working electrode - glassy carbon electrode coated with Pd / RuO2; the cyclic voltammetry potential scan range is set to -0.924-0.276V vs.Hg / HgO, and the point interval is 0.001V; the sensitivity is 0.001A / V; the test atmosphere is argon gas with a gas flow rate of 20 to 30mL / min continuously ventilated into the electrochemical cell.

[0015] The purpose of the present invention is to further reduce the amount of palladium used and solve the problem of H ad The problem of difficult desorption. The prepared material has high catalytic activity. The modification is purposefully carried out to solve the problems existing in the electrocatalytic process of formate. The above characteristics are helpful for the in-depth study of the electrooxidation process of formate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the microscopic morphology of the anode electrocatalyst Pd / RuO2 used in a direct formate fuel cell according to the present invention;

[0017] Figure 2 It is a schematic diagram of the X-ray photoelectron spectrum of the anode electrocatalyst Pd / RuO2 used in the direct formate fuel cell of the present invention;

[0018] Figure 3 It is a schematic diagram of the electrochemical performance of the anode electrocatalyst Pd / RuO2 used in a direct formate fuel cell according to the present invention;

[0019] Figure 4 This is a schematic diagram of the chronoamperometric test results of the anode electrocatalyst Pd / RuO2 for a direct formate fuel cell according to the present invention;

[0020] Figure 5 It is a schematic diagram of the cyclic voltammetry test results (multiple tests after activation) of the anode electrocatalyst Pd / RuO2 used for direct formate fuel cell of the present invention.

[0021] Table 1 shows the palladium content measured by inductively coupled plasma emission spectroscopy in the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below through specific implementation modes, but the present invention is not limited to the following embodiments.

[0023] Preparation method:

[0024] Add 4 mg of palladium chloride and 4 μl of concentrated hydrochloric acid to 3 ml of deionized water, and after complete dissolution by ultrasonication, transfer to a volumetric flask and dilute to 10 mL. Ultrasonicate 50 mg of RuO2 in 80 mL of deionized water; drop 10 mL of chloropalladium acid solution, stir at 70 ° C for 5 hours; wash with water and ethanol; vacuum dry at 70 ° C for 10 hours; calcine the dried product at 400 ° C in a tube furnace under argon atmosphere for 2 hours, and obtain the product Pd / RuO2 after natural cooling.

[0025] Table 1

[0026]

[0027] In this embodiment, the microscopic morphology of the product was characterized and analyzed using a scanning electron microscope. Figure 1 It can be seen that the catalyst presents a linear structure.

[0028] Figure 2 This is a schematic diagram of the X-ray photoelectron spectrum of this product; Figure 2 It can be seen that this product contains palladium, ruthenium and oxygen. Some literature points out that defective oxygen (O def ) will produce active oxygen species, which will react with the adsorbed intermediates on the palladium. From the O1s diagram, it can be seen that this product contains more active oxygen species, so it can solve the problem of difficult desorption of adsorbed hydrogen during the electro-oxidation of formate.

[0029] Figure 3This is a schematic diagram of the electrochemical performance of the material of the present invention; the specific experimental parameters are: electrolysis in 1M potassium hydroxide and 1M potassium formate solution; a three-electrode system is used: counter electrode - platinum wire, reference electrode - Hg / HgO electrode, working electrode - glassy carbon electrode coated with Pd / RuO2; the cyclic voltammetry potential scanning range is set to -0.924-0.276V vs.Hg / HgO, the point interval is 0.001V; the sensitivity is 0.001A / V; the test atmosphere is argon gas flow rate of 20-30mL / min continuously ventilated to the electrochemical cell. Figure 3 It can be seen that in the positive scan process of the cyclic voltammogram, at the oxidation voltage of -0.35 V, there is only the oxidation peak of formate, and the oxidation peak current in this state is 2.68A mg -1 , no peak of adsorbed hydrogen appeared at about -0.30 V under high potential, indicating that the adsorbed hydrogen on palladium can be oxidized in time, solving the problem of hydrogen poisoning in the formate oxidation process.

[0030] Figure 4 This is a schematic diagram of the chronoamperometric test results of this product. The specific experimental parameters are: the potential is set to -0.474Vvs.Hg / HgO, the point interval is 0.001V; the sensitivity is 0.001A / V. After 1500s of testing, Pd / RuO2 still retains a high current density of 30.5% for electrocatalytic potassium formate. The improvement in the stability of Pd / RuO2 should be attributed to the improvement in the removal ability of intermediates, which can expose more active sites to maintain electrocatalytic ability.

[0031] from Figure 5 This is the result of multiple cyclic voltammetry tests on this product after activation. The specific experimental parameters are: electrolysis in 1M potassium hydroxide and 1M potassium formate solution; a three-electrode system: counter electrode - platinum wire, reference electrode - Hg / HgO electrode, working electrode - glassy carbon electrode coated with Pd / RuO2; the cyclic voltammetry potential scan range is set to -0.924-0.276V vs.Hg / HgO, and the point interval is 0.001V; the sensitivity is 0.001A / V; the test atmosphere is argon gas continuously ventilated into the electrochemical cell at a flow rate of 20-30mL / min. The box in the figure corresponds to the peak of intermediate desorption at high potential. From Figure 5 It can be seen that after multiple cyclic voltammetry scans, no peak of intermediate desorption was observed in the forward scan process, indicating that this product can effectively promote the removal of intermediates.

[0032] Table 1 shows the palladium content in the product measured by inductively coupled plasma emission spectrometry. The palladium content is 2.83wt%, which is much lower than the palladium content (20wt%) in commercial palladium carbon. This reduces the cost of the catalyst and is conducive to its commercial development.

[0033] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. An application of a carrier-metal strong interaction catalyst for a direct formate fuel cell anode, wherein the carrier-metal strong interaction catalyst is palladium loaded on ruthenium dioxide, namely Pd / RuO2, and the loading amount of palladium is 2wt%-10wt%.

2. According to the use described in claim 1, the loading amount of palladium is 2wt%-7wt%.

3. According to the use of claim 1 or 2, the preparation method of the carrier-metal strong interaction catalyst comprises the following steps: (1) Preparation of chloropalladium acid solution; (2) ultrasonically dispersing RuO2 in deionized water; (3) adding the chloropalladium acid solution prepared in (1) dropwise into (2), and stirring the mixed solution at 70° C. for 5 h; washing the collected samples with water and ethanol, and drying them in vacuum; (4) The sample of step (3) was placed in a tubular furnace and calcined at 400°C for 2 h under an argon atmosphere, and then naturally cooled to obtain the product Pd / RuO2.

4. The use according to claim 3, characterized in that The preparation of the chloropalladic acid solution is as follows: palladium chloride is dispersed in water, and then concentrated hydrochloric acid is added, wherein for every 4-8 mg of palladium chloride, there is 2-4 ml of deionized water and 4-8 μl of concentrated hydrochloric acid; the stirring is magnetic stirring to form a uniformly dispersed system.

5. The use according to claim 3, characterized in that In step (2), every 50 mg of RuO2 corresponds to 70-100 mL of deionized water.

6. The use according to claim 1 or 2, wherein Pd / RuO2 is used for the anode of a direct formate fuel cell to overcome hydrogen poisoning.

7. The use according to claim 1 or 2, characterized in that: Electrolysis was performed in 1M KOH+1M HCOOK solution; a three-electrode system was used: counter electrode - platinum wire, reference electrode - Hg / HgO electrode, working electrode - glassy carbon electrode coated with Pd / RuO2; the cyclic voltammetry potential scan range was set to -0.924-0.276V vs. Hg / HgO, with a point interval of 0.001V; the sensitivity was 0.001A / V; the test atmosphere was argon gas continuously ventilated into the electrochemical cell at a gas flow rate of 20-30mL / min.

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