A MoO x Modified PtCo nanochain and its preparation method and application

Abstract

The present invention provides a MoO x -modified PtCo nanochain and its preparation method and application. The MoO x -modified PtCo nanochain includes a one-dimensional linear PtCo nanochain, and the surface of the PtCo nanochain is modified with MoO x . The PtCo nanochain is formed by connecting PtCo nanoparticles in series with PtCo nanowires. The MoO x -modified PtCo nanochain of the present invention, as an electrocatalyst, has better performance than commercial Pt / C and unmodified PtCo nanochains. The mass activity is nearly 13 times higher than that of commercial Pt / C, and it has higher catalytic activity and anti-poisoning ability, enabling the catalyst to maintain high electrocatalytic performance for a long time.

Description

Technical Field

[0001] The present invention relates to the field of electrocatalysts, in particular to a MoO x Modified PtCo nanochains and preparation methods and applications thereof. Background Art

[0002] In the face of increasingly severe energy and environmental problems, it is particularly important to find clean and efficient green energy to replace traditional fossil energy. Fuel cells have the characteristics of high energy conversion efficiency, high power density, low noise and zero pollution, and have broad application prospects. During the anode reaction of fuel cells - methanol oxidation reaction, the catalyst is easily poisoned and deactivated, resulting in poor stability and low service life. Therefore, solving the poisoning problem is the key to improving battery life.

[0003] It is well known that metal Pt is the best single metal catalyst for methanol oxidation reaction. However, Pt has limited reserves, high price, slow reaction rate, and is easily poisoned by intermediate products such as CO during the reaction, which seriously limits its industrial application. PtCo nanomaterials are considered to be good catalysts for methanol oxidation reaction. In addition to reducing costs, the synergistic effect of PtCo effectively improves the reaction efficiency, but the CO poisoning problem in these alloy catalysts still exists. How to improve the anti-poisoning ability of Pt-based nanocatalysts and further improve their catalytic performance in alcohol oxidation reactions is still an urgent problem to be solved. Summary of the invention

[0004] The present invention proposes a MoO x Modified PtCo nanochain and its preparation method and application, prepared MoO x The modified PtCo nanochains have excellent catalytic activity for methanol oxidation as electrocatalysts, with the mass activity nearly 13 times higher than that of commercial Pt / C, and have excellent resistance to CO poisoning.

[0005] The technical solution of the present invention is achieved in this way: a MoO x Modified PtCo nanochains, including one-dimensional linear PtCo nanochains, the surface of the PtCo nanochains is modified with MoO x ,PtCo nanochain is composed of PtCo nanowires connecting PtCo nanoparticles in series.

[0006] Furthermore, MoO x After modification, the size of PtCo nanoparticles is 5-10 nm, the diameter of PtCo nanowires is 0.5-3 nm, and the length of PtCo nanochains is 50-500 nm.

[0007] Mo atoms are oxidized to different valence states, namely MoO xThe MoO x Pt and Co are evenly distributed in the modified PtCo nanochains, and Mo is modified on their surfaces in an oxidized form.

[0008] A MoO x The preparation method of the modified PtCo nanochain comprises the following steps:

[0009] (1) dispersing a metal precursor, a surfactant and a reducing agent in a solvent to obtain a solution A, wherein the metal precursor includes a Pt source and a Co source;

[0010] (2) heating solution A under closed conditions for reaction, and then naturally cooling to room temperature to obtain solution B;

[0011] (3) adding the molybdenum source to solution B, mixing evenly with ultrasound, heating in an oil bath, and cooling to room temperature to obtain solution C;

[0012] (4) Centrifuging solution C to obtain an intermediate product, washing the intermediate product, and drying it under vacuum to obtain MoO x Modified PtCo nanochains.

[0013] Furthermore, in step (1), the amount of Pt source is 20-40 mg, the amount of Co source is 4-8 mg, the amount of surfactant is 30-35 mg, the amount of reducing agent is 50-150 mg, and the volume of solvent is 15-25 mL; in step (3), the amount of Mo source is 9-20 mg.

[0014] Furthermore, in step (1), the Pt source is platinum acetylacetonate, the Co source is cobalt acetylacetonate, the surfactant is hexadecyltrimethylammonium chloride, the reducing agent is glucose, and the solvent is oleylamine.

[0015] Further, the Mo source is molybdenum carbonyl.

[0016] Furthermore, in step (2), the temperature of the heating reaction is 130-190° C., and the reaction time is 4-20 hours; in step (3), the temperature of the heating reaction is 130-180° C., and the reaction time is 1-3 hours.

[0017] Furthermore, in step (1), dispersion is carried out by ultrasound, and the ultrasound time is not less than 0.5 hours; in step (4), the specific method for washing the intermediate product is: the intermediate product is dispersed in ethanol by ultrasound, and then centrifuged and precipitated, and repeated 3-6 times.

[0018] A MoO x Modified PtCo nanochains prepared by the method.

[0019] A MoO xApplication of modified PtCo nanochains as electrocatalysts.

[0020] Beneficial effects of the present invention:

[0021] MoO of the present invention x PtCo nanochains modified by MoO x Modified on the surface of PtCo nanochains; Mo atoms are oxidized to different valence states to form MoO x The PtCo nanochain has a Pt-rich surface and MoO x The combination of the two has a good reaction mechanism in the electrocatalytic reaction, and has very good catalytic performance and resistance to CO poisoning.

[0022] The preparation method of the present invention is divided into two steps, but the operation is simple and easy to implement, with good repeatability and high yield; in the same system, changing the reaction conditions can achieve controllable regulation of the catalyst components, etc., which is a simple and efficient preparation method.

[0023] MoO of the present invention x The modified PtCo nanochains are used in fuel cells to catalyze the anode reaction - the alcohol oxidation reaction. Their performance is better than that of commercial Pt / C, and their mass activity is nearly 13 times higher than that of commercial Pt / C, showing higher catalytic activity. Compared with PtCo nanochains, MoO x The modified PtCo nanochains have a better reaction mechanism and have good anti-CO poisoning ability through synergistic effect with the Pt surface; at the same time, MoO x The modified PtCo nanoparticles have a higher surface-to-body ratio and provide more active sites in the electrocatalytic reaction. x The modified PtCo nanoparticles also perform well in catalyzing other electrochemical reactions, such as oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, and perhydrolysis reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 MoO x Schematic diagram of the preparation process of modified PtCo nanochains;

[0026] Figure 2 For MoO xMorphology of the modified PtCo nanochains;

[0027] Figure 3 For MoO x Structural diagram of the modified PtCo nanochains;

[0028] Figure 4 For MoO x The test curves of PtCo nanochains before and after modification and commercial Pt / C catalyzing methanol oxidation reaction and the comparison of their mass activity and specific activity.

[0029] Figure 5 To modify MoO x CO dissolution curves of PtCo nanochains before and after. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] like Figure 1 As shown, a MoO x The preparation method of the modified PtCo nanochain comprises the following steps:

[0033] (1) Weigh 30 mg of platinum acetylacetonate, 7 mg of cobalt acetylacetonate, 32 mg of hexadecyltrimethylammonium chloride, and 90 mg of glucose respectively into a beaker, then add 20 mL of oleylamine into the beaker, and mix by ultrasonication for 1 hour to obtain a solution A;

[0034] (2) Solution A was transferred to a 25 mL reactor liner, sealed, heated to 160° C. and maintained for 12 hours. After the reaction was completed, the reactor was naturally cooled to room temperature and then taken out to obtain Solution B;

[0035] (3) Weigh 10 mg of carbonyl molybdenum and place it in solution B, mix it evenly with ultrasonic for 0.5 hours, transfer it to a flask and heat it in an oil bath to 160° C. for 2 hours. After the reaction is completed, cool it naturally to room temperature to obtain solution C;

[0036] (4) Solution C was centrifuged to obtain an intermediate product, which was dispersed in ethanol by ultrasonication and then centrifuged to precipitate. The dispersion and centrifugation treatment was repeated three times and dried under vacuum to obtain MoO x Modified PtCo nanochains, MoO xThe modified PtCo nanochains were placed in a vacuum drying oven and stored at room temperature.

[0037] Figure 2 The MoO prepared in this example x Morphology of the modified PtCo nanochain (transmission electron microscope photo). Figure 2 It can be seen from (ab) that MoO x The size of the modified PtCo nanoparticles is 5-10 nm, the diameter of the nanowires is 0.5-3 nm, and the length is 50-500 nm. Figure 2 As can be seen from (cf), Pt, Co, Mo, and O are evenly distributed, with the Pt atom content being the largest and more obvious, and the Mo atom content being less and only being modified on the surface. x The modified PtCo nanochains have the advantages of alloys and excellent electrocatalytic performance. x Therefore, it has a better electrocatalytic reaction mechanism and strong resistance to CO poisoning.

[0038] Figure 3 The MoO prepared in this example x Structural spectrum of the modified PtCo nanochain (X-ray diffraction spectrum). Compared with the PtCo nanochain, the modified MoO x No new diffraction peaks appeared after the addition, indicating that Mo was modified on the surface of the nanochain in the form of oxide.

[0039] Comparative Example 1

[0040] The preparation method of PtCo nanochain comprises the following steps: 30 mg of platinum acetylacetonate, 7 mg of cobalt acetylacetonate, 32 mg of hexadecyltrimethylammonium chloride and 90 mg of glucose are dissolved in 20 mL of oleylamine, and after ultrasonic homogenization, the mixture is transferred to a reaction kettle and reacted at 160° C. for 12 hours, and then naturally cooled, centrifuged, washed and dried to obtain the PtCo nanochain.

[0041] Figure 4 The MoO prepared in Example 1 x Modified PtCo nanochains (MoO x -PtCo PNCs) and Comparative Example 1 Unmodified MoO x The test results of methanol oxidation catalyzed by PtCo nanochains (PtCo PNCs) and commercial Pt / C, including their mass activity and column comparison chart. Commercial Pt / C was purchased from Shanghai Hesen Electric Co., Ltd., model: HPT040. The test environment is based on the three-electrode system of the electrochemical workstation. Figure 4(ab) Linear sweep voltammetry was used to test the mixed electrolyte solution of 0.5M H2SO4 and 1M methanol. From the test results, it can be seen that PtCo nanochains, MoO x The mass activities of the modified PtCo nanochains and commercial Pt / C are 0.65 A mg Pt -1 、3.01A mg Pt -1 , 0.22A mg Pt -1 (vs.RHE), modified MoO x The performance of the modified MoO x PtCo nanochains compared to unmodified MoO x The PtCo nanochains prepared by this method have been significantly improved. x The modified PtCo nanochains have excellent catalytic activity for methanol oxidation and can also be used to improve the methanol oxidation performance of Pt alloy nanocatalysts.

[0042] Figure 5 The modified MoO prepared in Example 1 is shown x The CO dissolution curve test of the PtCo nanochain before and after in 0.5MH2SO4 electrolyte solution reflects the anti-poisoning ability of the sample to CO. x The CO oxidation potential of the modified PtCo nanochains is only 0.348 mV, which is significantly better than that of the unmodified MoO x PtCo nanochains, showing the MoO prepared by this method x The PtCo nanochains have excellent electrochemical resistance to CO poisoning.

[0043] Example 2

[0044] like Figure 1 As shown, a MoO x The preparation method of the modified PtCo nanochain comprises the following steps:

[0045] (1) Weigh 20 mg of platinum acetylacetonate, 4 mg of cobalt acetylacetonate, 30 mg of hexadecyltrimethylammonium chloride, and 50 mg of glucose respectively into a beaker, then add 15 mL of oleylamine into the beaker, and mix by ultrasonication for 1 hour to obtain a solution A;

[0046] (2) Solution A was transferred to a 25 mL reactor liner, sealed, heated to 130° C. and maintained for 20 hours. After the reaction was completed, the reactor was naturally cooled to room temperature and then taken out to obtain Solution B;

[0047] (3) Weigh 9 mg of carbonyl molybdenum into solution B, mix evenly with ultrasonic for 0.5 hours, transfer to a flask, heat in an oil bath to 130° C. and maintain for 3 hours. After the reaction is completed, naturally cool to room temperature to obtain solution C;

[0048] (4) Solution C was centrifuged to obtain an intermediate product, which was dispersed in ethanol by ultrasonication and then centrifuged to precipitate. The dispersion and centrifugation treatment was repeated three times and dried under vacuum to obtain MoO x Modified PtCo nanochains, MoO x The modified PtCo nanochains were placed in a vacuum drying oven and stored at room temperature.

[0049] The MoO prepared in this example x Modified PtCo nanochains (MoO x -PtCo PNCs) with a mass activity of 2.91Amg Pt -1 .

[0050] Example 3

[0051] like Figure 1 As shown, a MoO x The preparation method of the modified PtCo nanochain comprises the following steps:

[0052] (1) Weigh 40 mg of platinum acetylacetonate, 8 mg of cobalt acetylacetonate, 35 mg of hexadecyltrimethylammonium chloride, and 150 mg of glucose respectively into a beaker, then add 25 mL of oleylamine into the beaker, and mix by ultrasonication for 1 hour to obtain a solution A;

[0053] (2) Solution A was transferred to a 25 mL reactor liner, sealed, heated to 190° C. and maintained for 4 hours. After the reaction was completed, the reactor was naturally cooled to room temperature and then taken out to obtain Solution B;

[0054] (3) Weigh 20 mg of carbonyl molybdenum into solution B, mix evenly with ultrasonic for 0.5 hour, transfer to a flask, heat in an oil bath to 180° C. and maintain for 1 hour, and cool naturally to room temperature after the reaction to obtain solution C;

[0055] (4) Solution C was centrifuged to obtain an intermediate product, which was dispersed in ethanol by ultrasonication and then centrifuged to precipitate. The dispersion and centrifugation treatment was repeated 6 times and dried under vacuum to obtain MoO x Modified PtCo nanochains, MoO x The modified PtCo nanochains were placed in a vacuum drying oven and stored at room temperature.

[0056] The MoO prepared in this example x Modified PtCo nanochains (MoOx -PtCo PNCs) with a mass activity of 2.67Amg Pt -1 .

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A MoO x The method for preparing the modified PtCo nanochain is characterized in that: The following steps are involved: (1) dispersing a metal precursor, a surfactant and a reducing agent in a solvent to obtain a solution A, wherein the metal precursor includes a Pt source and a Co source; (2) Solution A is heated under closed conditions for reaction, and then naturally cooled to room temperature to obtain solution B; (3) Add the Mo source to solution B, mix evenly with ultrasonic wave, heat in an oil bath, and cool to room temperature to obtain solution C; (4) Solution C is centrifuged to obtain an intermediate product, which is then washed and dried under vacuum to obtain MoO x Modified PtCo nanochains; In step (1), the amount of Pt source is 20-40 mg, the amount of Co source is 4-8 mg, the amount of surfactant is 30-35 mg, the amount of reducing agent is 50-150 mg, and the volume of solvent is 15-25 mL; the Pt source is platinum acetylacetonate, the Co source is cobalt acetylacetonate, the surfactant is hexadecyltrimethylammonium chloride, the reducing agent is glucose, and the solvent is oleylamine; In step (3), the amount of Mo source used is 9-20 mg, and the Mo source is carbonyl molybdenum; In step (2), the heating reaction temperature is 130-190°C, and the reaction time is 2-20 hours; in step (3), the heating reaction temperature is 130-190°C, and the reaction time is 1-3 hours; The MoO x The modified PtCo nanochains include one-dimensional linear PtCo nanochains, and the surface of the PtCo nanochains is modified with MoO x ,PtCo nanochain is composed of PtCo nanowires connecting PtCo nanoparticles in series.

2. The preparation method according to claim 1, characterized in that: MoO x After modification, the size of PtCo nanoparticles is 5-10 nm, the diameter of PtCo nanowires is 0.5-3 nm, and the length of PtCo nanochains is 50-500 nm.

3. The preparation method according to claim 1, characterized in that: In step (4), the specific method for washing the intermediate product is: dispersing the intermediate product in ethanol by ultrasonication, and then centrifuging and precipitating, and repeating 2-8 times.

4. MoO prepared by the preparation method according to any one of claims 1 to 3 x Modified PtCo nanochains.

5. MoO according to claim 4 x Application of modified PtCo nanochains as electrocatalysts.

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