Pd-Sb nano worm chain ethanol oxidation catalyst and preparation method thereof

Abstract

The invention discloses a Pd-Sb nano worm chain ethanol oxidation catalyst and a preparation method thereof, and relates to the technical field of inorganic nano functional materials. The invention relates to a preparation method of a PdSb nano worm chain ethanol oxidation catalyst. The raw materials comprise SbCl3, Pd (acac) 2, polyvinylpyrrolidone, hexadecyl trimethyl ammonium bromide, citric acid, dimethylformamide and W (CO) 6. The PdSb nano worm chain ethanol oxidation catalyst disclosed by the invention shows excellent electro-catalytic ethanol oxidation activity, relatively low initial potential, relatively high quality current density and good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic nanofunctional materials, and particularly relates to a Pd-Sb nanoworm chain ethanol oxidation catalyst and a preparation method thereof. BACKGROUND

[0002] The excessive use of traditional fossil fuels and the increasing environmental pollution have attracted widespread attention, and the development of new clean energy has attracted more and more attention. Direct ethanol fuel cells (DEFC) have attracted widespread interest of scientists due to their advantages of clean and environmental protection, high energy density, etc. However, due to the difficulty of multi-electron transfer and C-C bond breaking of ethanol molecules, the oxidation reaction process of ethanol is slow in kinetics and the reaction path is complex, so it is urgent to develop high-efficiency ethanol oxidation reaction (EOR) catalysts.

[0003] Early studies have shown that Pd-based noble metals and their derivatives are one of the currently optimal ethanol oxidation catalysts, but their limited specific surface area, insufficient stability, and easy accumulation of intermediates and passivation of catalytic sites during the reaction process seriously restrict their further development and application. In addition, the surface structure and electronic state of the catalyst play a key role in regulating its catalytic performance, therefore, developing new structure and composition regulation strategies has become a key direction to improve the performance of ethanol oxidation reaction.

[0004] In recent years, it has been found that regulating the electronic structure of Pd by hetero-metallic doping is an effective means to improve its catalytic performance. After Sb element forms an alloy with Pd, the d-orbital electron arrangement of Pd can be effectively adjusted, and the adsorption and desorption processes of reaction intermediates can be optimized, thereby significantly improving the catalytic activity and anti-poisoning ability. Further studies have shown that the nanostructure morphology of the catalyst also has a significant impact on its performance.

[0005] Compared with nanoparticles or bulk materials, metal nanoworm chain (NW) can accelerate the directional transfer and diffusion of electrons or ions, thereby significantly improving the efficiency of electrocatalytic reaction. Therefore, metal nanochain can be used as an ideal platform for electrochemical catalysis. In the prior art, the synthesis methods of worm-like nanostructures, such as molecular brush (MBB) synthesis, crystallization-driven self-assembly (CDSA), polymerization-induced self-assembly (PISA) and the like, have the following disadvantages: poor structural stability and uneven morphology. The prior art with the publication number CN102806079B and the title of a preparation method of Pd / SnO2 / C composite nanocatalyst introduces SnO2 into the Pd catalyst system for catalytic oxidation of ethanol to prepare a Pd / SnO2 / C composite nanocatalyst. The metal nanowire Pd material prepared by the prior art with the publication number CN103397217B and the title of a metal nanowire Pd material with electro-oxidation catalytic performance and a preparation method thereof exhibits excellent room-temperature ethanol and methanol electro-oxidation reaction catalytic performance in alkaline solution, and can be used as an anode reaction catalyst for alkaline ethanol fuel cell or directly as an anode support material. Compared with Pt-based and nanoporous gold materials, the material has a cost advantage. However, the catalysts of the above technologies cannot improve the durability while ensuring a low initial potential and a high mass current density.

[0006] In summary, the ethanol oxidation catalysts in the prior art have the following technical defects: poor durability and inability to simultaneously achieve a low initial potential and a high mass current density. SUMMARY

[0007] In view of the above technical problems, the present application provides a Pd-Sb nanoworm chain ethanol oxidation catalyst and a preparation method thereof, which achieves the following application purposes: improving the durability of the ethanol oxidation catalyst while ensuring a high mass current density and a low initial potential.

[0008] To achieve the above application purposes, the present application adopts the following technical solutions: A preparation method of a PdSb nanoworm chain ethanol oxidation catalyst, comprising the following steps: 1) mixing and stirring SbCl3, Pd(acac)2, polyvinylpyrrolidone, cetyltrimethylammonium bromide, citric acid and dimethylformamide to obtain a mixture A; The mass ratio of the SbCl3, Pd(acac)2, polyvinylpyrrolidone, cetyltrimethylammonium bromide and citric acid is 4-16:30-50:60-100:100-200:300-400; the mass ratio of dimethylformamide to Pd(acac)2 is 400-600:1.

[0009] 2) Add W(CO)6 to the mixture A, and react for 1 hour under the condition of 80±5℃ oil bath, and the obtained product is PdSb precursor in the form of ultra-small nanoparticles. The amount of W(CO)6 is 0.13% of the mass of the mixture A.

[0010] Add polyvinylpyrrolidone (PVP) and ethylene glycol (EG) to the PdSb precursor obtained in step 2, and transfer to a stainless steel reaction kettle with a polytetrafluoroethylene liner, and place the reaction kettle in an oven at 180-200℃ for 2 hours to obtain a PdSb nanoworm chain ethanol oxidation catalyst.

[0011] The polyvinylpyrrolidone has an average molecular weight of about 360000 and a K value in the range of 80-100.

[0012] The amount of polyvinylpyrrolidone is 5% of the mass of the mixture A.

[0013] The amount of EG is 2.4 times the mass of the mixture A.

[0014] Advantages of the present application: 1. The PdSb nanoworm chain ethanol oxidation catalyst of the present application exhibits excellent electrocatalytic ethanol oxidation activity and has a broad application prospect.

[0015] 2. The PdSb nanoworm chain ethanol oxidation catalyst of the present application has a uniform structure, rich active sites, and a large surface contact area, which promotes the adsorption and activation of reactants, significantly improves the catalytic efficiency of ethanol oxidation reaction, avoids the agglomeration phenomenon, and ensures the high efficiency and stability of the reaction; the electrochemical active surface area of the PdSb nanoworm chain structure reaches 60 m 2 / g. The catalyst of the present application exhibits good stability at a potential of-0.2 V, and the initial current density is 120 mA / cm², and no significant decline is observed within 1 hour.

[0016] 3. The catalyst of the present application utilizes the synergistic effect of metal alloying and nanostructure construction to effectively improve the catalytic activity and stability. The catalyst exhibits a low initial potential and a high mass current density; the initial potential is about 0.4 V vs. RHE, and the mass current density is about 120 mA / cm 2 .

[0017] 4. The preparation method of the PdSb nanoworm chain ethanol oxidation catalyst of the present application can prepare PdSb nanoworm chains with uniform structure and unique morphology; the preparation process is simple to operate, suitable for laboratory and large-scale production, low in cost, and easy to popularize and apply. The catalyst exhibits excellent electrocatalytic activity and stability for ethanol oxidation reaction in alkaline medium, and has high practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A transmission electron microscope (TEM) photo of the PdSb precursor in step 2 of the present application, taken by a JEOL-1400 transmission electron microscope; Figure 2 A transmission electron microscope (TEM) photo of the PdSb nanoworm chain ethanol oxidation catalyst of the present application, taken by a JEOL-1400 transmission electron microscope; Figure 3 An X-ray diffraction (XRD) pattern of the PdSb nanoworm chain ethanol oxidation catalyst of the present application; Figure 4 An ethanol electrocatalytic oxidation performance test curve obtained from the ethanol electrocatalytic oxidation performance characterization test in Example 3; Figure 5 A CO elution curve of the PdSb nanoworm chain ethanol oxidation catalyst prepared in Example 1 of the present application and a commercial palladium-carbon catalyst; Figure 6 An i-t test curve of the stability detection of the PdSb nanoworm chain ethanol oxidation catalyst prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0019] The present application will be further described in detail by specific implementation examples in combination with the accompanying drawings, but these examples do not limit the protection scope of the present application.

[0020] Example 1 A preparation method of a PdSb nanoworm chain ethanol oxidation catalyst 1) SbCl3, Pd(acac)2, polyvinylpyrrolidone, cetyltrimethylammonium bromide, citric acid and dimethylformamide are mixed and stirred uniformly to obtain a mixture A; The mass ratio of the SbCl3, Pd(acac)2, polyvinylpyrrolidone, cetyltrimethylammonium bromide and citric acid is 5:31:60:120:340; the mass ratio of dimethylformamide to Pd(acac)2 is 600:1.

[0021] The polyvinylpyrrolidone has an average molecular weight of 40000 and a K value ranging between 27 and 32.

[0022] 2) W(CO)6 is added to the mixture A, and the reaction is carried out at 80°C under oil bath conditions for 1 hour, and the obtained product is an ultra-small nanoparticle-shaped PdSb precursor. The amount of W(CO)6 is 0.13% of the mass of the mixture A.

[0023] 3) Add polyvinylpyrrolidone (PVP) and EG to the PdSb precursor obtained in step 2, and transfer to a stainless steel reaction kettle lined with polytetrafluoroethylene, and place the reaction kettle in an oven at 180°C for two hours to obtain a PdSb nanoworm chain ethanol oxidation catalyst.

[0024] The polyvinylpyrrolidone has an average molecular weight of 360,000 and a K value ranging from 80 to 100.

[0025] The amount of polyvinylpyrrolidone used is 5% of the mass of mixture A.

[0026] The amount of EG used is 2.4 times the mass of mixture A.

[0027] Example 2: A method for preparing a PdSb nanoworm chain ethanol oxidation catalyst 1) Mix SbCl3, Pd(acac)2, polyvinylpyrrolidone, cetyltrimethylammonium bromide, citric acid, and dimethylformamide, and stir until uniform to obtain mixture A; The mass ratio of SbCl3, Pd(acac)2, polyvinylpyrrolidone, cetyltrimethylammonium bromide, and citric acid is 16:50:100:200:400; the mass ratio of dimethylformamide to Pd(acac)2 is 400:1.

[0028] 2) Add W(CO)6 to mixture A, and react at 80°C in an oil bath for 1 hour to obtain a PdSb precursor in the form of ultra-small nanoparticles. The amount of W(CO)6 used is 0.13% of the mass of mixture A.

[0029] 3) Add polyvinylpyrrolidone (PVP) and EG to the PdSb precursor obtained in step 2, and transfer to a stainless steel reaction kettle lined with polytetrafluoroethylene, and place the reaction kettle in an oven at 180~200°C for two hours to obtain a PdSb nanoworm chain ethanol oxidation catalyst.

[0030] The polyvinylpyrrolidone has an average molecular weight of about 360,000 and a K value ranging from 80 to 100.

[0031] The amount of polyvinylpyrrolidone used is 5% of the mass of mixture A.

[0032] The amount of EG used is 2.4 times the mass of mixture A.

[0033] A transmission electron microscopy (TEM) image of the PdSb nanoworm-like chain ethanol oxidation catalyst of the present invention, taken using a JEOL-1400 transmission electron microscope. The image shows that the catalyst is composed of uniformly sized nanoparticles connected end-to-end, forming a worm-like, one-dimensional chain. The particles are tightly packed, have natural curvature, and exhibit good overall continuity and dispersion. The particle size is approximately 10 nm, demonstrating precise morphology control and uniform structure.

[0034] Example 3 Inspection test

[0035] (1) Characterization test of ethanol electrocatalytic oxidation performance The ethanol electrocatalytic oxidation performance characterization test of the PdSb nanoworm chain ethanol oxidation catalyst prepared in Example 1 was carried out using a Chenhua CHI 760D electrochemical workstation.

[0036] A glassy carbon electrode (3 mm in diameter) was used as the working electrode. A PdSb nanoworm chain ethanol oxidation catalyst was uniformly loaded onto the working electrode surface and dried. A platinum wire was used as the counter electrode. An Ag / AgCl electrode was selected as the reference electrode, supplemented with a saturated KCl solution, forming a three-electrode system. The electrolyte system consisted of a water-ethanol mixture of KOH, with a KOH concentration of 1.0 mol·L·L in the mixture. -1 , the concentration of ethanol in the mixed solution is 1.0 mol・L -1 .

[0037] During the test, the potential window was -0.8 V ~ -0.3 V (vs. Ag / AgCl) at a scan rate of 100 mV·s -1 Cyclic voltammetry (CV) tests were conducted to examine the catalytic performance of the PdSb nanoworm chain ethanol oxidation catalyst (PdSb NWs), palladium antimony nanoparticles (PdSb NPs), and commercial Pd / C catalyst (0.02 mol) for the electrocatalytic oxidation of ethanol. The resulting ethanol electrocatalytic oxidation performance curve is shown in the attached figure. Figure 4 .

[0038] Analysis Attachment Figure 4 It can be seen that the PdSb nanoworm chain ethanol oxidation catalyst of the present invention exhibits the best electrocatalytic activity and has the highest current density (about 120 mA / cm 2 ) and the lowest starting potential (about 0.4 V vs. RHE), making it suitable as a catalyst for ethanol electrocatalytic oxidation reaction.

[0039] (2) Detect and draw the CO dissolution curves of the PdSb nanoworm chain ethanol oxidation catalyst (PdSb NWs) and the commercial palladium carbon catalyst (Commercial Pd / C) prepared in Example 1, as shown in the attached figure. Figure 5 ; This figure compares the electrochemically active surface area (ECSA) of the tested catalysts. Calculation shows that the electrochemically active surface area of ​​the commercial palladium carbon catalyst (Commercial Pd / C) is 48m 2 / g, and the electrochemically active surface area of ​​PdSb nanoworm chain ethanol oxidation catalyst (PdSb NWs) is 60 m 2 / g, and the electrochemical active surface area has been significantly improved.

[0040] (3) The stability of the PdSb nanoworm chain ethanol oxidation catalyst (PdSb NWs) prepared in Example 1 was tested by chronoamperometry (IT method) at room temperature. 0.07 mg of the catalyst was tested in 1 M KOH + 1 M ethanol solution. The IT test curve is shown in the attached figure. Figure 6 As shown in Figure 2, the PdSb nanoworm chain ethanol oxidation catalyst (PdSb NWs) prepared in Example 1 showed good stability at a potential of -0.2 V, with an initial current density of 120 mA / cm² and no obvious decay within 1 hour.

Claims

1. A method for preparing a PdSb nanoworm chain ethanol oxidation catalyst, characterized by: The raw materials used include SbCl3, Pd(acac)2, polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, citric acid, dimethylformamide and W(CO)6.

2. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 1, characterized in that: The following steps are involved: 1) SbCl3, Pd(acac)2, polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, citric acid, and dimethylformamide were mixed and stirred to obtain a mixture A; 2) Add W(CO)6 to mixture A and react under oil bath conditions to obtain a PdSb precursor.

3. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 2, characterized in that: The method further comprises the following steps: adding polyvinyl pyrrolidone and ethylene glycol to the PdSb precursor obtained in step 2, reacting to obtain a PdSb nano-worm chain ethanol oxidation catalyst.

4. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 2, characterized in that: The oil bath temperature is 80±5° C. and the reaction time is 1 to 1.5 hours.

5. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 3, characterized in that: The reaction temperature is 180-200° C., and the reaction time is 2-2.5 hours.

6. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 1, characterized in that: The mass ratio of SbCl3, Pd(acac)2, polyvinyl pyrrolidone, cetyltrimethylammonium bromide, and citric acid is 4-16:30-50:60-100:100-200:300-400; the mass ratio of dimethylformamide to Pd(acac)2 is 400-600:

1.

7. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 2, characterized in that: The amount of W(CO)6 used is 0.13% of the mass of mixture A.

8. The method for preparing a PdSb nanoworm chain ethanol oxidation catalyst according to claim 3, characterized in that: The polyvinyl pyrrolidone has an average molecular weight of about 360,000 and a K value ranging from 80 to 100.

9. A PdSb nanoworm chain ethanol oxidation catalyst, characterized by: Prepared according to the preparation method according to any one of claims 1 to 8, the shape is a one-dimensional chain.

10. An application of a PdSb nanoworm chain ethanol oxidation catalyst, characterized by: Use of the catalyst prepared by the preparation method according to any one of claims 1 to 8 in an ethanol oxidation reaction.

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