Anti-poisoning electro-catalysis formic acid oxidation catalyst and preparation process thereof

Abstract

The invention relates to the technical field of electrochemistry and energy, in particular to an anti-poisoning electro-catalysis formic acid oxidation catalyst and a preparation process thereof.The anti-poisoning electro-catalysis formic acid oxidation catalyst comprises carbon paper, tungsten oxide and palladium nanoparticles, the tungsten oxide is loaded on the carbon paper and is in a three-dimensional cluster spine shape, and the palladium nanoparticles are modified on the surface of the tungsten oxide; a tungsten oxide micron structure grows on a carbon paper substrate in situ through a hydrothermal synthesis method to form a multidirectional disorderly crossed three-dimensional micron network, and spiny nano strips uniformly cover the surface of a single carbon fiber; the palladium nanoparticles are loaded on the surface of the tungsten oxide or embedded into the tungsten oxide through a pulse electrodeposition method. The problems of limited activity, CO poisoning and low precious metal utilization rate of a traditional catalyst are comprehensively solved through spine-shaped structure design, precious metal gradient distribution and interface synergistic effect, and the catalyst has the advantages of high catalytic efficiency, high poisoning resistance and low cost.

Description

Technical Field

[0001] The present invention relates to the field of electrochemistry and energy technology, and in particular to a poisoning-resistant electrocatalytic formic acid oxidation catalyst and a preparation process thereof. Background Art

[0002] With the continuous increase in global energy demand and the increasing severity of environmental pollution, the search for clean and efficient energy conversion technologies has become a research hotspot. Fuel cells, as a power generation technology with high energy conversion efficiency and low emissions, have attracted widespread attention. Among them, direct formic acid fuel cells (DMFCs) have become a key area of ​​focus in the fuel cell field due to their high energy density, environmental friendliness, and simple reaction pathway. The formic acid oxidation reaction (FAOR) is the core electrocatalytic step in DMFCs and determines the performance and efficiency of the cell. However, there are several technical bottlenecks in the formic acid oxidation reaction, with the selection and performance of catalysts being a key technical challenge. The electrocatalytic formic acid oxidation reaction (FAOR) generally requires the use of highly active catalysts, especially precious metal materials (such as Pt and Pd), which are widely used due to their excellent catalytic performance. Byproducts easily generated during formic acid oxidation, such as carbon monoxide (CO), often adsorb on the catalyst surface, leading to catalyst deactivation and thus affecting reaction efficiency. Therefore, improving catalyst stability, resistance to CO poisoning, and long-term durability has become a major challenge in the field of formic acid electrocatalysis.

[0003] At the microscopic level, in the electrocatalytic formic acid oxidation reaction, the structure, morphology and surface properties of the catalyst surface have a decisive influence on the reaction activity. For noble metal catalysts (such as Pt and Pd), their surfaces are usually used to adsorb reactants, and the catalytic process involves electron transfer between the reactants and the catalyst surface and the desorption process of reaction intermediates. The CO poisoning effect (i.e., the adsorption of the reaction intermediate CO leads to the blockage of active sites on the catalyst surface) has always been a key factor limiting the performance of noble metal catalysts. In order to improve the performance of catalysts, researchers have conducted a lot of exploration in catalyst design, among which the design of three-dimensional nanostructures and composite materials has received widespread attention. In particular, by constructing catalysts with high specific surface area, porosity or spiky structures, not only can the effective surface area of ​​the catalyst be increased, but also the rapid desorption of reactants and intermediates can be promoted during the reaction, thereby reducing the risk of CO poisoning and improving the stability of the catalyst.

[0004] In the prior art, noble metals (such as platinum (Pt) and palladium (Pd)) are widely used in the electrocatalytic formic acid oxidation reaction due to their excellent catalytic activity. However, numerous studies have shown that when noble metals exist in a single metal form, their catalytic activity and stability in FAOR still have significant limitations. Monometallic catalysts are easily adsorbed and poisoned by intermediates (such as CO) during the reaction, resulting in the blocking of active sites on the catalyst surface and a rapid decrease in catalytic efficiency, making it difficult to meet the requirements for high activity and high stability in practical applications.

[0005] In addition, metal oxides (such as TiO2, WO3, Co3, O4, etc.) have become potential supports for precious metal catalysts due to their high stability and strong redox properties. Precious metals are usually loaded on oxide supports to improve metal utilization and enhance catalytic activity.

[0006] For example, WO3-supported Pt and Pd catalysts: Ur Rehman A et al. prepared a Pt / Pd / WO3-OMC composite catalyst. OMC stands for Ordered Mesoporous Carbon. WO3 was first loaded onto OMC, forming a micrometer-scale rope-like morphology that intertwined with each other. Pd and Pt nanoparticles were then thermally reduced onto WO3 for formic acid electrooxidation. Compared to the Pd / OMC catalyst, the Pd / WO3-OMC electrocatalyst exhibited higher electrocatalytic activity and long-term formic acid oxidation stability. The incorporation of Pt enhanced the Pd2Pt1 / WO3-OMC catalyst's tolerance to CO poisoning. Despite this improved CO poisoning resistance, the Pd / WO3-OMC composite catalyst's catalytic activity was only 15% higher than that of Pd / OMC and was still limited by the inherently low catalytic activity of WO3. The fewer Pd active sites on the WO3 surface resulted in a relatively slow overall reaction rate, which compromised the catalytic performance.

[0007] Wan et al. uniformly deposited Pd nanoparticles on the surface of TiO2 nanoparticles via an impregnation-reduction method and then mixed them with carbon black to form a composite catalyst (Pd / TiO2–C). The TiO2:C mass ratio was controlled to be 1:1 to achieve an optimal balance between conductivity and synergistic effects. Compared with the traditional Pd / C catalyst, the Pd / TiO2–C (1:1) catalyst exhibited a higher electrochemical specific surface area (ECSA) and stronger resistance to CO poisoning. CV and CA tests showed that the catalyst exhibited a higher initial current density and lower peak shift in formic acid oxidation, indicating that formic acid was more readily oxidized. The well-controlled particle size (~3.5 nm) resulted in a more uniform dispersion of Pd on the TiO2 surface, which facilitated the utilization of the precious metal. Although TiO2 as a support for the Pd catalyst improved catalytic activity to some extent, due to its inherently poor conductivity, it still required the addition of carbon materials to maintain overall electron transfer efficiency. At the same time, the structural morphology of this type of catalyst is relatively traditional, and key aspects such as interfacial gas evacuation and catalytic channel structure have not been deeply optimized, which limits its further development in more efficient and stable FAOR catalyst systems.

[0008] From these examples of composite catalysts, it can be seen that although metal oxides have shown certain advantages in inhibiting CO poisoning and enhancing stability, their catalytic activity is usually limited, and the synergistic effect of metal oxides and precious metals often cannot find a balance between efficient catalysis and resistance to CO poisoning.

[0009] Spike-like structures have become a hot topic in electrocatalytic research in recent years due to their high specific surface area, special geometric shape and excellent underwater aerophobicity. Spike-like oxides can effectively increase the surface area and active sites of the catalyst through microstructural design, improve the diffusion rate of reactants, and reduce the adsorption of reaction intermediates (such as CO) on the surface. Zhou et al. directly deposited Pd metal on carbon paper. The Pd formed a spike-like morphology. The palladium nanoarray with super aerophobic properties solved the problems of bubble accumulation and gas transmission barriers on the surface of traditional electrodes. The electrode showed a high power density (35.8mW / cm 2 ) and good stability. The use of Pd nanoarray electrodes significantly improves the catalytic performance of formic acid electrooxidation, especially in terms of bubble removal and gas transport. However, the utilization rate of Pd metal is too low, and too much Pd cannot participate in the reaction inside the spikes. High cost and low mass activity are still the main problems limiting its widespread application. Further optimization and solutions are needed by reducing the amount of precious metals, increasing metal utilization, and improving catalytic activity. Summary of the Invention

[0010] To solve the above problems, the present invention provides a poisoning-resistant electrocatalytic formic acid oxidation catalyst and a preparation process thereof, which comprehensively solves the problems of limited activity of traditional catalysts, CO poisoning and low precious metal utilization through spike-like structure design, precious metal gradient distribution and interface synergy, and has the advantages of high catalytic efficiency, strong anti-poisoning ability and low cost.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows: a poisoning-resistant electrocatalytic formic acid oxidation catalyst comprising carbon paper, tungsten oxide and palladium nanoparticles, wherein the tungsten oxide is a particle with a diameter of less than 10 μm, the tungsten oxide is supported on the carbon paper in the form of three-dimensional clustered spikes, and the palladium nanoparticles are modified on the surface of the tungsten oxide;

[0012] Tungsten oxide microstructures are grown in situ on a carbon paper substrate through a hydrothermal synthesis method, forming a multi-directional, disordered, and cross-linked three-dimensional micron network. The surface of a single carbon fiber is evenly covered with thorn-like nanosheets or nanostrips. Palladium nanoparticles are loaded onto the surface of tungsten oxide through a pulsed electrodeposition method, forming a metallized thorn-like composite structure with increased surface roughness and local formation of clustered or stacked sheet-like connections.

[0013] Furthermore, the tungsten oxide microstructured thorn-like nanosheets / nanobars have a length of 200 to 800 nm, a width of 50 to 200 nm, and a deposition density on the surface of the thorn-like structure of 0.1 to 0.5 mg / cm 2 .

[0014] Furthermore, the palladium nanoparticles have a particle size of 200 nm and a surface coverage density of 10^3 to 10^4 particles / μm 2 , and presents a gradient enrichment distribution on the surface of tungsten oxide spikes.

[0015] Furthermore, when the poisoning-resistant electrocatalytic formic acid oxidation catalyst was subjected to cyclic voltammetry testing in 1 mol / L formic acid and 0.1 mol / L perchloric acid solutions, the peak current of the formic acid oxidation reaction was ≥120 mA, and the forward sweep current and reverse sweep current curves were consistent, showing excellent resistance to CO poisoning.

[0016] Furthermore, when the electroplating time of the poisoning-resistant electrocatalytic formic acid oxidation catalyst was 0.5 to 15 minutes, the overall thorn-like structure was completely retained, and after being soaked in a perchloric acid solution for 24 hours, the peak current of the formic acid oxidation reaction increased by more than 10 mA.

[0017] A preparation process of a poisoning-resistant electrocatalytic formic acid oxidation catalyst, comprising the following steps:

[0018] S1, hydrothermal synthesis of tungsten oxide carrier: Sodium tungstate dihydrate was dissolved in deionized water, concentrated nitric acid was added dropwise to adjust the pH to 1.5, carbon paper with an area of ​​​​1 was added, and the reaction was hydrothermally reacted at 180°C for 28 hours. The carbon paper was washed several times and dried to obtain tungsten oxide-loaded carbon paper, which was recorded as WO3 / CP;

[0019] S2, electrodeposition of palladium nanoparticles: a solution containing HClO4 and NaPdCl4 was prepared as an electrodeposition solution, WO3 / CP was clamped with an electrode clamp as a working electrode, a Pt sheet was used as a counter electrode, and a saturated calomel electrode was used as a reference electrode. A pulsed electrodeposition method was used to apply voltages of +0.5 V and ~0.1 V to the positive and negative electrodes, respectively. The duration of the applied voltage was 1 to 100 ms, and the total deposition time was any time within the range of 0.5 min to 15 min, thereby obtaining a catalyst with Pd deposited on tungsten oxide-supported carbon paper, which was recorded as Pd-WO3 / CP.

[0020] S3, acid washing activation: the obtained Pd-WO3 / CP was immersed in a perchloric acid solution for 24 h to further enhance the catalytic activity.

[0021] Furthermore, in S1, the mass of sodium tungstate dihydrate is 0.67 g, the volume of deionized water is 20 ml, and the area of ​​carbon paper is 1*3 cm 2 .

[0022] Furthermore, in S2, the concentrations of HClO4 and NaPdCl4 solutions are 0.1 mol / L and 0.5-100 mmol / L, respectively.

[0023] Furthermore, in S2, the pulsed electrodeposition method was used with a pulse frequency of 5 to 500 Hz, WO3 / CP was used as the working electrode, and the electrode was clamped with an electrode clamp, and the electroplating area was 1 × 1 cm 2 .

[0024] Furthermore, in S2, after electrodeposition, gradient drying is performed under nitrogen protection, first drying at 60°C for 1 hour, and then heating to 80°C for 2 hours.

[0025] The above scheme has the following beneficial effects:

[0026] This scheme boasts high specific surface area and high catalytic activity: Tungsten oxide is supported on carbon paper in a three-dimensional, clustered, spiky microstructure, forming a multidirectional, disordered, and open network. This significantly increases the specific surface area, exposing more active sites and promoting the adsorption and reaction of formic acid molecules. Palladium nanoparticles are then distributed and modified on the tungsten oxide spike surface via a gradient enrichment pattern, forming a "metallized thorn forest" structure that enhances interfacial electron transfer efficiency. The catalyst achieves a peak current of ≥120 mA for formic acid oxidation, a significant improvement over conventional Pd / C catalysts, achieving highly efficient catalysis.

[0027] 2. This scheme has excellent resistance to CO poisoning: the gas-repellent properties of the spike-like structure and the open channel design effectively accelerate the rapid desorption of reaction products and avoid the accumulation of CO intermediates on the catalyst surface; the forward current and reverse current curves are consistent, indicating that the CO adsorption poisoning phenomenon is significantly suppressed, the catalytic active sites are stable for a long time, and no obvious poisoning peaks appear in the cyclic voltammetry test.

[0028] 3. This scheme uses pulse electrodeposition combined with a gradient drying process (60°C → 80°C) to achieve high dispersion and uniform loading of palladium nanoparticles, reduce precious metal agglomeration, and achieve a particle surface coverage density of 10^3 to 10^4 particles / μm. 2 , significantly improving Pd utilization. The coordinated optimization of electrodeposition time and acid wash activation enables the catalyst to maintain a high peak current at low precious metal loading, reducing precious metal usage and production costs.

[0029] 4. This scheme has a stable and durable structure: the three-dimensional spike-shaped tungsten oxide substrate is grown in situ by a hydrothermal method, and is firmly bonded to the carbon paper interface to prevent structural collapse; the palladium particles form a strong electronic interaction with the tungsten oxide interface (Pd-WO3 synergistic effect), and WO3 acts as a proton reservoir to promote H + The catalyst can be activated by the catalyst to remove the adsorbents and to dynamically regulate the adsorption behavior of the intermediates, thus extending the catalyst life. The activity is still improved after 24 hours of acid washing, proving that the structure has excellent corrosion resistance and stability.

[0030] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the steps of the preparation method of the anti-poisoning electrocatalytic formic acid oxidation catalyst and the preparation process embodiment of the present invention;

[0032] Figure 2 The XRD test patterns of the original spike-shaped tungsten oxide-supported carbon paper and its electrodeposited palladium particles (electrodeposition time is 10 min) of the anti-poisoning electrocatalytic formic acid oxidation catalyst and its preparation process embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the enlarged structure of the original spike-shaped tungsten oxide-supported carbon paper according to an embodiment of the present invention's anti-poisoning electrocatalytic formic acid oxidation catalyst and its preparation process;

[0034] Figure 4 Schematic diagram of the composite catalyst structure after electroplating palladium particles (electroplating time is 10 min) according to an embodiment of the present invention's anti-poisoning electrocatalytic formic acid oxidation catalyst and its preparation process;

[0035] Figure 5The formic acid oxidation curve test results of the anti-poisoning electrocatalytic formic acid oxidation catalyst and the preparation process embodiment of the present invention after electrodeposition of palladium particles (electrodeposition time is 5 to 15 minutes);

[0036] Figure 6 The XRD test patterns of the original spike-shaped tungsten oxide-supported carbon paper and its electrodeposited palladium particles (electrodeposition time is 60s) of the anti-poisoning electrocatalytic formic acid oxidation catalyst and its preparation process embodiment of the present invention;

[0037] Figure 7 Schematic diagram of the composite catalyst structure after electro-deposition of palladium particles (electro-deposition time is 30 to 60 seconds) according to an embodiment of the present invention's anti-poisoning electrocatalytic formic acid oxidation catalyst and its preparation process;

[0038] Figure 8 These are the test results of formic acid oxidation curves after electro-depositing palladium particles (electro-deposition time is 30 to 60 seconds) of the anti-poisoning electrocatalytic formic acid oxidation catalyst and its preparation process embodiment of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0042] The following is further described in detail through specific implementation methods:

[0043] Example 1:

[0044] As attached Figure 1 As shown: This embodiment synthesizes a spike-shaped anti-poisoning electrocatalytic formic acid oxidation catalyst, including carbon paper, tungsten oxide and palladium nanoparticles. The tungsten oxide is a particle with a diameter of less than 10 μm. The tungsten oxide is supported on the carbon paper in a three-dimensional clustered spike shape, and the palladium nanoparticles are modified on the surface of the tungsten oxide.

[0045] Tungsten oxide microstructures are grown in situ on a carbon paper substrate through a hydrothermal synthesis method, forming a multi-directional, disordered, and cross-linked three-dimensional micron network. The surface of a single carbon fiber is evenly covered with thorn-like nanosheets or nanostrips. Palladium nanoparticles are loaded onto the surface of tungsten oxide through a pulsed electrodeposition method, forming a metallized thorn-like composite structure with increased surface roughness and local formation of clustered or stacked sheet-like connections.

[0046] The thorn-like nanosheets / nanobars of tungsten oxide microstructures have a length of 200-800 nm and a width of 50-200 nm. The deposition density on the surface of the thorn-like structure is 0.1-0.5 mg / cm 2 .

[0047] The particle size of palladium nanoparticles is 200nm, and the surface coverage density is 10^3~10^4 particles / μm 2 , and presents a gradient enrichment distribution on the surface of tungsten oxide spikes.

[0048] When the poisoning-resistant electrocatalytic formic acid oxidation catalyst was subjected to cyclic voltammetry testing in 1 mol / L formic acid and 0.1 mol / L perchloric acid solutions, the peak current of the formic acid oxidation reaction was ≥120 mA, and the forward sweep current and reverse sweep current curves were consistent.

[0049] When the electrodeposition time of the poisoning-resistant electrocatalytic formic acid oxidation catalyst is 0.5 to 15 minutes, the overall thorn-like structure is completely retained, and after immersion in perchloric acid solution for 24 hours, the peak current of the formic acid oxidation reaction is increased by more than 10 mA.

[0050] A poisoning-resistant electrocatalytic formic acid oxidation catalyst prepared based on the materials described in Example 1 comprises the following steps:

[0051] S1, hydrothermal synthesis of tungsten oxide carrier: 0.67g sodium tungstate dihydrate was dissolved in 20ml deionized water, concentrated nitric acid was added dropwise to adjust the pH to 1.5, carbon paper was added, and the hydrothermal reaction was carried out at 180℃ for 28h. The heating rate of the hydrothermal reaction was 3-5℃ / min. After the reaction, graded cooling was adopted, first cooling to 100℃ at 2℃ / min and then naturally cooling to room temperature. The carbon paper with tungsten oxide loading was taken out and rinsed several times. After drying, the carbon paper was obtained, which was recorded as WO3 / CP.

[0052] S2, electroplating palladium nanoparticles: Prepare a solution of 0.1 mol / L HClO4 and 0.5-100 m mol / L NaPdCl4 as the electroplating solution, clamp the WO3 / CP with an electrode clamp as the working electrode, and the electroplating area is 1×1 cm 2 , a Pt sheet electrode was used as the counter electrode, a saturated calomel electrode was used as the reference electrode, and a pulse electrodeposition method was used to apply voltages of +0.5 V and -0.1 V. The applied voltage lasted for 1 to 100 ms and the pulse frequency was 5 to 500 Hz. WO3 / CP was used as the working electrode and clamped with an electrode clip. The electroplating area was 1 × 1 cm 2 , the total deposition time is within any time range of 5 to 15 minutes, and a catalyst with Pd deposited on tungsten oxide-supported carbon paper is obtained, which is recorded as Pd-WO3 / CP; after deposition, gradient drying is adopted under nitrogen protection, first drying at 60°C for 1 hour, and then heating to 80°C for 2 hours.

[0053] S3, acid washing activation: the obtained Pd-WO3 / CP was immersed in a perchloric acid solution for 24 h to further enhance the catalytic activity.

[0054] The specific implementation process is as follows: First, tungsten oxide is loaded onto carbon paper via a hydrothermal synthesis method: 6.7g of sodium tungstate dihydrate is dissolved in 20ml of deionized water and stirred at room temperature until the solute is completely dissolved. Concentrated nitric acid is added dropwise to adjust the pH to 1.5, and carbon paper is added. After a hydrothermal reaction at 180°C for 28 hours, the carbon paper is removed, rinsed several times, and dried to obtain the tungsten oxide-loaded carbon paper, designated WO3 / CP.

[0055] The obtained WO3 was subjected to XRD test, and the test results were as follows Figure 2 As shown; SEM test was also carried out, and the test results are shown Figure 3 shown.

[0056] A solution of 0.1 mol / L HClO4 and 5 m mol / L NaPdCl4 was prepared as the electrodeposition solution, WO3 / CP was used as the working electrode, and the electroplating area was 1 × 1 cm 2 The Pt sheet electrode was used as the counter electrode and the saturated calomel electrode was used as the reference electrode. The voltage of +0.5V and -0.1V was applied by pulse electrodeposition method with a duration of 5ms. The deposition time was set to 5min, 8min, 10min, 12min, and 15min to obtain Pd 5min -WO3 / CP、Pd 8min -WO3 / CP、Pd 10min -WO3 / CP、Pd 12min -WO3 / CP、Pd 15min-WO3 / CP, after deposition, gradient drying was performed under nitrogen protection, first drying at 60℃ for 1h, then heating to 80℃ for 2h. All the obtained Pd-WO3 / CP samples were immersed in perchloric acid solution for 24h.

[0057] The obtained Pd 10min -WO3 / CP was tested by XRD, the test results are as follows Figure 2 As shown; SEM test was carried out at the same time, and the test results were as follows Figure 4 shown.

[0058] Figure 2 The XRD test proved the successful synthesis of WO3 / CP. After 10 minutes of electroplating, the peak of WO3 became weak and difficult to observe, and the metal peak of palladium proved the successful electroplating of palladium nanoparticles.

[0059] Figure 4 The SEM image shows that palladium nanoparticles are loaded on the surface of tungsten oxide by pulse electrodeposition, forming a metallized thorn-like composite structure with increased surface roughness and local formation of clustered or stacked sheet connections.

[0060] All the obtained Pd-WO3 / CP were subjected to formic acid oxidation electrochemical tests, and the test instrument used was the CHI electrochemical workstation produced by Shanghai Chenhua Company.

[0061] The test method is as follows:

[0062] The Pd-WO3 / CP sample was clamped with an electrode clamp as the working electrode; the Pt sheet electrode was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode. Electrochemical tests were carried out in an aqueous solution containing 0.1 M perchloric acid and 1 M formic acid.

[0063] The electrochemical test results are as follows Figure 5 shown.

[0064] Figure 5 The curve results show that when the electrodeposition time is 5 to 15 minutes, the Pd-WO3 / CP samples of this example all exhibit a high peak current for the formic acid oxidation reaction. For example, when the electroplating time is 5 minutes, the peak current for the formic acid oxidation reaction is 92 mA; when the electroplating time is 10 minutes, the peak current for the formic acid oxidation reaction is 120 mA. The forward and reverse currents of the Pd-WO3 / CP during this electroplating period show consistent curves, indicating that no poisoning occurs and that the surface aerophobic structure can effectively prevent CO poisoning.

[0065] Example 2:

[0066] The difference from Example 1 is that the electrodeposition time is shortened in step S2 and the deposition time is set to 30s, 40s, 50s, and 60s, and the samples are marked as Pd30s -WO3 / CP、Pd 40s -WO3 / CP、Pd 50s -WO3 / CP、Pd 60s -WO3 / CP.

[0067] The obtained Pd 60s -WO3 / CP was tested by XRD, the test results are as follows Figure 6 As shown; SEM test was carried out at the same time, and the test results were as follows Figure 7 shown.

[0068] Figure 6 The XRD test results demonstrated the successful incorporation of palladium nanoparticles.

[0069] Figure 7 The SEM images show that electroplating palladium nanoparticles at a low electroplating time does not change the morphology of tungsten oxide, indicating that the palladium nanoparticles exist in the form of extremely small particles.

[0070] All the obtained Pd-WO3 / CP were subjected to formic acid oxidation electrochemical tests, and the test instrument used was the CHI electrochemical workstation produced by Shanghai Chenhua Company.

[0071] The test method is as follows:

[0072] The Pd-WO3 / CP sample was clamped with an electrode clamp as the working electrode; the Pt sheet electrode was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode. Electrochemical tests were carried out in an aqueous solution containing 0.1 M perchloric acid and 1 M formic acid.

[0073] The electrochemical test results are as follows Figure 8 shown.

[0074] Figure 8 The formic acid oxidation polarization curve shows that when the electrodeposition time is as low as 60 seconds, the peak current of the formic acid oxidation reaction remains considerable, at 67 mA. As the electroplating time decreases, the peak potential of formic acid oxidation shifts forward, demonstrating a lower overpotential requirement. This means that the reaction can proceed efficiently at a potential closer to the theoretical potential, indicating that the system has low polarization losses, which is conducive to improving energy efficiency.

[0075] Example 3:

[0076] The difference from Example 2 is that molybdenum oxide is deposited on the surface of carbon paper, and Pd metal is loaded on the molybdenum oxide by electroplating.

[0077] Example 4:

[0078] The difference from Example 3 is that cerium oxide is loaded on the surface of carbon paper, and Pd metal is loaded on the cerium oxide by electroplating.

[0079] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A poisoning-resistant electrocatalytic formic acid oxidation catalyst, characterized in that: The invention comprises carbon paper, tungsten oxide and palladium nanoparticles. The tungsten oxide is a particle with a diameter of less than 10 μm. The tungsten oxide is loaded on the carbon paper in the form of three-dimensional clustered spikes. The palladium nanoparticles are modified on the surface of the tungsten oxide. Tungsten oxide microstructures are grown in situ on a carbon paper substrate through a hydrothermal synthesis method, forming a multi-directional, disordered, and cross-linked three-dimensional micron network. The surface of a single carbon fiber is evenly covered with thorn-like nanosheets or nanostrips. Palladium nanoparticles are loaded onto the surface of tungsten oxide through a pulsed electrodeposition method, forming a metallized thorn-like composite structure with increased surface roughness and local formation of clustered or stacked sheet-like connections.

2. The poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 1, characterized in that: The thorn-like nanosheets / nanobars of tungsten oxide microstructures have a length of 200-800 nm and a width of 50-200 nm. The deposition density on the surface of the thorn-like structure is 0.1-0.5 mg / cm 2 .

3. The poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 2, characterized in that: The particle size of palladium nanoparticles is 200nm, and the surface coverage density is 10^3~10^4 particles / μm 2 , and presents a gradient enrichment distribution on the surface of tungsten oxide spikes.

4. The poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 3, characterized in that: When the poisoning-resistant electrocatalytic formic acid oxidation catalyst was subjected to cyclic voltammetry testing in 1 mol / L formic acid and 0.1 mol / L perchloric acid solutions, the peak current of the formic acid oxidation reaction was ≥120 mA, and the forward sweep current and reverse sweep current curves were consistent.

5. The poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 4, characterized in that: When the electrodeposition time of the poisoning-resistant electrocatalytic formic acid oxidation catalyst is 0.5 to 15 minutes, the overall thorn-like structure is completely retained, and after immersion in perchloric acid solution for 24 hours, the peak current of the formic acid oxidation reaction is increased by more than 10 mA.

6. A process for preparing a poisoning-resistant electrocatalytic formic acid oxidation catalyst, comprising: The following steps are involved: S1, hydrothermal synthesis of tungsten oxide carrier: Sodium tungstate dihydrate was dissolved in deionized water, concentrated nitric acid was added dropwise to adjust the pH to 1.5, carbon paper was added, and the reaction was hydrothermally reacted at 180°C for 28 hours. The carbon paper was washed several times and dried to obtain tungsten oxide-loaded carbon paper, which was recorded as WO3 / CP. S2, electrodeposition of palladium nanoparticles: a solution containing HClO4 and NaPdCl4 was prepared as an electrodeposition solution, WO3 / CP was clamped with an electrode clamp as a working electrode, a Pt sheet was used as a counter electrode, and a saturated calomel electrode was used as a reference electrode. A pulsed electrodeposition method was used to apply a voltage of +0.5V and -0.1V to the positive and negative electrodes, respectively. The duration of the applied voltage was 1 to 100ms, and the total deposition time was any time within the range of 0.5 to 15min, thereby obtaining a catalyst with Pd deposited on tungsten oxide-supported carbon paper, which was recorded as Pd-WO3 / CP. S3, acid washing activation: the obtained Pd-WO3 / CP was immersed in a perchloric acid solution for 24 h to further enhance the catalytic activity.

7. The preparation process of the poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 6, characterized in that: In S1, the heating rate of the hydrothermal reaction is 3-5°C / min. After the reaction, step cooling is adopted, firstly decreasing the temperature to 100°C at 2°C / min and then naturally cooling to room temperature.

8. The preparation process of the poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 7, characterized in that: In S2, the concentrations of HClO4 and NaPdCl4 solutions are 0.1 mol / L and 0.5-100 m mol / L, respectively.

9. The preparation process of the poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 8, characterized in that: In S2, the pulsed electrodeposition method was used with a pulse frequency of 5 to 500 Hz, WO3 / CP was used as the working electrode, and the electrode was clamped with an electrode clamp. The electroplating area was 1 × 1 cm 2 .

10. The preparation process of the poisoning-resistant electrocatalytic formic acid oxidation catalyst according to claim 9, characterized in that: In S2, after electrodeposition, gradient drying under nitrogen protection is adopted, first drying at 60°C for 1 hour, and then heating to 80°C for 2 hours.

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