CN116005194A - A kind of transition metal doped nickel phosphide integral composite electrocatalytic material, preparation method and application - Google Patents

Abstract

The invention provides a transition metal doped nickel phosphide integral composite electrocatalytic material, a preparation method and application thereof, belonging to the technical field of electrocatalytic material preparation, wherein the preparation method comprises the following steps: (1) The nickel-based material is used as a carrier after pretreatment, and then copper salt and cobalt salt mixed raw material liquid with certain concentration and molar ratio are prepared. (2) Putting a nickel substrate into a hydrothermal kettle, adding raw material liquid, and then putting into an oven for constant-temperature hydrothermal treatment to obtain a transition metal doped integral composite material pre-product; (3) And (3) treating the hydrothermal pre-product in a tubular furnace by using a phosphating process to obtain the transition metal doped nickel phosphide integral composite catalytic material. The invention has the following advantages: firstly, the method has the advantages of simple technical process, small operation difficulty, wide raw material sources and low production cost. Secondly, the transition metal doped nickel phosphide integral composite catalytic material prepared by the method has the advantages of high catalytic activity, stable active substances, high selectivity and the like.

Description

A kind of transition metal doped nickel phosphide integral composite electrocatalytic material, preparation method and application

technical field

The invention relates to a preparation method and application of a transition metal-doped nickel phosphide integral composite electrocatalytic material, belonging to the technical field of electrocatalytic material preparation.

Background technique

Electrocatalytic water splitting hydrogen production technology has become a promising energy conversion technology due to its mild operating conditions and clean and pollution-free characteristics. The water splitting process mainly includes the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. For the overall water electrolysis reaction, HER is a simple two-electron transfer, while OER involves a complex four-electron transfer process, which makes the OER process the rate-limiting step in water electrolysis. Theory shows that the thermodynamic potential for overall water splitting is 1.23 V in both acidic and alkaline electrolytes. In order to achieve efficient water splitting, it is necessary to apply a voltage much higher than 1.23 V to achieve a considerable current density, which increases the cost of electrolyzing water to produce hydrogen. Compared with the hydrogen produced by HER, the added value of oxygen produced by anode OER is lower, and the coexistence of hydrogen and oxygen can easily cause safety hazards. In order to solve a series of problems faced by the electrocatalytic water splitting hydrogen production technology, the hybrid electrolytic water technology based on the combination of cathodic hydrogen evolution and anodic organic oxidation has highlighted its advantages. At the anode, the organic substrate in the electrolyte usually has good water solubility. Thermodynamically, the energy barrier required for the electrochemical oxidation of organic matter is lower than OER, which is expected to replace OER, and ultimately, contribute to green hydrogen and value-added high-fine chemicals manufactured at the same time.

At present, the global annual output of polyester plastics such as polyethylene terephthalate (PET) is about 65-70 million tons, and its production mainly depends on terephthalic acid derived from petroleum, which has limited resources and environment. limit. Polyethylene 2,5-furandicarboxylate (PEF) plastic is one of the most promising alternatives to PET plastic thanks to lower overall carbon emissions in production and better availability. PEF is produced by polymerizing biomass-based 2,5-furandicarboxylic acid (FDCA) with ethylene glycol. Studies have shown that FDCA has been used as a high value-added biological and chemical intermediate, and the US Department of Energy has also listed FDCA as one of the 12 priority compounds for establishing the future green chemical industry. At present, FDCA is mainly produced by the oxidation of 5-hydroxymethylfurfural (HMF), which can be obtained from the dehydration conversion of hexoses, by traditional thermocatalytic techniques. Compared with traditional thermal catalysis, electrocatalytic conversion has the advantages of mild reaction conditions, controllable process and simple operation. Thus, the combination of electrochemical HMF oxidation and water splitting can realize the coupled production of high-value-added FDCA and high-purity hydrogen, and give full play to the advantages of hybrid electrolyzed water. In addition, HMF has good water solubility, and its electrooxidation thermodynamic potential is 0.11V, which is much lower than the thermodynamic potential of water splitting (1.23V), which can replace the OER reaction with a higher energy barrier at the anode. The development of high-performance and low-cost electrocatalysts is also an important part of achieving efficient water splitting. At present, the existing HMF oxidation electrocatalysts are mainly noble metal catalysts such as palladium, platinum, or gold, which are difficult to realize large-scale utilization due to their high cost and limited resources. Transition metals, such as manganese, iron, nickel, cobalt, copper, etc., have the advantages of wide sources and low cost. Therefore, the development of transition metal electrocatalysts that are easy for large-scale production, high performance and high stability has become a need for the development of electrocatalysis.

The existing transition metal catalytic materials are affected by their synthesis methods, and there are problems such as cumbersome synthesis process and long preparation time. The synthesized catalysts also have obvious defects in selectivity and service life. Using commercial nickel foam as the substrate, we firstly synthesized transition metal-doped monolithic composite pre-products by hydrothermal method. Then, after a phosphating process, a transition metal-doped nickel phosphide integral composite catalytic material with high activity and high stability can be formed. Compared with the catalysts reported at home and abroad, the catalytic material has obvious advantages in the performance of HMF electrooxidation. Commercialized nickel foam ensures a stable source of raw materials for the synthesis of catalysts, and hydrothermal reaction and phosphating processes are important technologies with the potential to expand production. In the follow-up, we should continue to explore the process conditions suitable for the scale-up production of this catalytic material, so as to lay a solid foundation for practical application.

Contents of the invention

In order to overcome the insufficient performance of existing materials, the object of the present invention is to provide a preparation method and application of a transition metal-doped nickel phosphide monolithic composite catalytic material. The method uses commercial, low-cost nickel foam as a carrier to synthesize a pre-product of a transition metal-doped overall composite material, and further cooperates with a simple phosphating process to synthesize a transition gold-doped nickel phosphide overall composite catalytic material. The process method has the advantages of low cost and low operation difficulty, and can prepare electrocatalytic anode materials with excellent performance. The composite catalytic material prepared by this process method has the advantages of high catalytic activity, long life, high selectivity, etc., and has great application potential in the field of catalysis. On this basis, the catalytic activity of HMF-assisted water splitting for hydrogen production was explored.

In order to realize the above-mentioned purpose of the invention, the technical scheme that the present invention takes is:

A preparation method of a transition metal-doped nickel phosphide overall composite catalytic material, comprising the following steps:

The first step is to prepare a transition metal-doped monolithic composite pre-product

1.1) Dissolving copper salt and cobalt salt in water to obtain a salt solution, then adding ammonium fluoride and urea to the above salt solution, stirring evenly to obtain an alkaline raw material solution.

1.2) Put nickel foam into a hydrothermal kettle lined with polytetrafluoroethylene, add the above-mentioned raw material solution, and place the hydrothermal kettle in water for ultrasonic treatment for 3 minutes. After ultrasonic treatment, carry out constant temperature hydrothermal reaction, 120°C-150°C constant temperature hydrothermal reaction for 4-6h. After the hydrothermal reaction, cool naturally in an oven to room temperature, open the hydrothermal kettle, rinse with water and ethanol, and obtain a transition metal-doped monolithic composite material pre-product.

The second step is to prepare transition metal-doped nickel phosphide monolithic composite catalytic materials

2.1) Rinse the pre-product of the transition metal-doped integral composite material obtained in the first step with water and ethanol, and put it into an oven for drying treatment.

2.2) Cut the dried pre-product of 1cm×2cm and put it in the porcelain state, and add 0-0.5g of phosphorus salt. Place the phosphate salt on the pre-product side and against the pre-product. Then put the porcelain state with the pre-product and phosphorus salt in the tube furnace, feed argon as a protective gas, and control the temperature of the tube furnace at 250-350°C. After phosphating for 0-1h, it is washed repeatedly with deionized water, put into an oven for drying treatment, and the transition metal-doped nickel phosphide overall composite catalytic material can be obtained. In order to ensure sufficient phosphating, the flow direction of argon must first pass through the phosphorus salt, and then pass through the pre-product.

Further, the nickel foam in the step 1.2) is a commercial nickel foam, the drying temperature is 60° C., and the drying time is 30 minutes. After washing and drying the nickel foam, it is added to the hydrothermal kettle.

Further, the cobalt salt in the step 1.1) is one of cobalt nitrate hexahydrate and cobalt chloride hexahydrate, preferably cobalt nitrate hexahydrate; the copper salt is one of copper nitrate trihydrate and copper chloride species, preferably copper nitrate trihydrate. The concentrations of cobalt nitrate hexahydrate, copper nitrate trihydrate, ammonium fluoride, and urea are preferably 0-1 mmol/L, 0-0.5 mmol/L, 3 mmol/L, and 6 mmol/L, respectively.

Further, 0-0.291g of cobalt salt and 0-0.121g of copper salt are added to every 40ml of water in the step 1.1).

Further, the ammonium fluoride in the step 1.1) can be replaced by ammonium bifluoride, and the urea can be replaced by potassium hydroxide.

Further, in the step 2.1), the drying temperature is 50° C. and the drying time is 15 minutes. In the step 2.1), the drying temperature is 50° C. and the drying time is 30 minutes.

Further, in the step 2.2), the flow rate of argon is controlled at 20-25ml/min.

Further, in the step 2.2), the phosphorus salt is one of sodium phosphate, sodium hypophosphite monohydrate, and potassium phosphate.

A transition metal-doped nickel phosphide integral composite catalytic material is prepared by the above method.

The application of the transition metal-doped nickel phosphide overall composite catalytic material prepared by the above method in the hydrogen production reaction of hybrid water electrolysis, specifically: the composite catalytic material obtained above is used as the anode to assemble a three-electrode test system, and the cathode uses A commercial Pt sheet electrode with a saturated Ag/AgCl reference electrode.

Analysis of the innovative point of the present invention: the nickel foam substrate used in the present invention has a porous structure, which can not only strengthen the mass transfer between the electrolyte and the surface of the catalyst, but also maintain good electrical conductivity and mechanical strength of the overall composite catalytic material. At the same time, the added additives such as urea or potassium hydroxide provide an alkaline environment during the hydrothermal process, which makes the nickel substrate partially dissolve in the reaction solution during the hydrothermal process. The dissolved nickel compound, copper salt, and cobalt salt form a composite catalytic material covering the surface of the nickel substrate, realizing the synthesis of an overall composite electrocatalytic anode material with nickel-rich surface without the addition of nickel salt. Additives such as ammonium fluoride (ammonium bifluoride) can modify the crystal structure of the composite catalytic material, so that the cobalt salt, copper salt and nickel compound dissolved in the reaction solution can be effectively combined to form an amorphous compound. Relying on the large surface area of porous nickel foam, this amorphous structure can provide more active sites, thus significantly lowering the energy barrier of electrochemical reactions. During phosphating, the phosphorus-containing steam produced by the decomposition of phosphorus salt under high temperature conditions is used to form phosphide on the surface of the pre-product. These phosphides form defective active sites, further reducing the activation energy of the reaction.

The beneficial effects of the present invention are:

(1) The method of the present invention has the advantages of simple technological process, low operation difficulty, wide sources of raw materials, low production cost, and can prepare composite catalytic materials with excellent performance. The XRD pattern shows the successful preparation of the amorphous material. On this basis, the catalytic activity of the catalytic material in electro-oxidation reaction in 1mol/L KOH, 0.05mol/L HMF electrolyte was explored. The results show that the initial potential of the whole system is close to the theoretical potential of 1.23V for electrolyzed water; the current density can reach 155mAcm ^-2 at an operating voltage of 1.5V; in the 9 cycle stability tests, the HMF conversion rate is 100%. showed good stability.

(2) In addition, compared with the catalytic materials reported by other works, the transition metal-doped nickel phosphide monolithic composite catalytic material prepared by this method has the advantages of high current density, stable active material, and high selectivity, and has a relatively high level in the field of catalysis. great application potential.

Description of drawings

Fig. 1 is the field emission scanning electron micrograph of the copper, cobalt doped nickel phosphide overall composite catalytic material prepared in Example 1.

Figure 2 is the XRD pattern of the copper and cobalt doped nickel phosphide overall composite catalytic material prepared in Example 1.

Fig. 3 is embodiment 1 (copper, cobalt-doped nickel phosphide monolithic composite catalytic material), 2 (copper-doped nickel phosphide monolithic composite catalytic material), 3 (copper-doped monolithic composite catalytic material), 4 (Cobalt-doped nickel phosphide monolithic composite catalytic material) and 5 (Cobalt-doped monolithic composite catalytic material) The linear voltammetry scans of the composite catalytic materials prepared.

Fig. 4 is the HMF oxidation cycle stability test diagram of Example 6 (copper, cobalt doped nickel phosphide overall composite catalytic material).

Fig. 5 is a diagram of Faraday efficiency of Examples 1-8.

Detailed ways

The present invention will be further described below in conjunction with embodiment.

Example 1

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut a 2.5cm×3.5cm nickel foam with a blade and place it vertically in a polytetrafluoroethylene hydrothermal kettle. Weigh 0.121g of copper nitrate, 0.291g of cobalt nitrate, 0.111g of ammonium fluoride and 0.36g of urea, mix with 40ml of deionized water and stir evenly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with water at a constant temperature of 120°C for 6 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain a pre-product of copper and cobalt-doped overall composite material. Rinse the obtained copper and cobalt-doped monolithic composite material pre-product with ethanol, and put it into an oven at 50° C. for constant temperature drying for 15 minutes. Cut the 1cm×2cm pre-product after hydroheating, put it into the porcelain state and add 0.5g of sodium hypophosphite monohydrate. Put Cizhou into a tube furnace and bake at 300°C for 1h, using argon as a protective gas, and the flow rate of argon is controlled at 20ml/min. After roasting, the overall composite catalytic material of nickel phosphide doped with copper and cobalt can be obtained. It can be seen from Figure 1 that a typical rod-shaped convex structure is formed on the surface of the phosphated nickel foam. In addition, it can be seen from Figure 2 that the obtained copper and cobalt-doped nickel phosphide overall composite catalytic material only shows the characteristic peaks of the nickel substrate in the XRD spectrum, so it is an amorphous composite material.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. As can be seen from accompanying drawing 3, solid line represents the linear voltammetry sweep curve (LSV) of the nickel phosphide overall composite catalytic material of synthesis copper, cobalt doping, and the initial potential of its HMF oxidation is very close to the thermodynamic potential of electrolytic water.

Example 2

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut the nickel foam with a blade to 2.5cm×3.5cm and place it vertically in a polytetrafluoroethylene hydrothermal kettle. Weigh 0.121g of copper nitrate, cobalt-free nitrate, 0.111g of ammonium fluoride and 0.36g of urea, mix with 40ml of deionized water and stir evenly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with water at a constant temperature of 130°C for 6 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain a copper-doped overall composite material pre-product. Rinse the pre-product of the copper-doped monolithic composite material obtained in step 2 with ethanol, and put it into an oven for drying at a constant temperature of 50° C. for 15 minutes. Cut the 1cm×2cm pre-product after hydroheating, put it into the porcelain state and add 0.5g of sodium hypophosphite monohydrate. Put Cizhou into a tube furnace and bake at 300°C for 1h, with argon as the protective gas, and the flow rate is controlled at 20ml/min. After firing, the copper-doped nickel phosphide overall composite catalytic material can be obtained.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. It can be seen from the short dotted line in Figure 3 that the copper-doped nickel phosphide overall composite catalytic material composite catalytic material corresponds to a current density of 100mA cm ^-2 at a voltage of 1.5Vvs.RHE, showing good HMF oxidation performance.

Example 3

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut the nickel foam with a blade to 2.5cm×3.5cm and place it vertically in a polytetrafluoroethylene hydrothermal kettle. Weigh 0.121g of copper nitrate, cobalt-free nitrate, 0.111g of ammonium fluoride and 0.36g of urea, mix with 40ml of deionized water and stir evenly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with water at a constant temperature of 120°C for 6 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain a copper-doped monolithic composite material. Rinse the copper-doped overall composite material obtained in step 2 with ethanol, put it in an oven for 15 minutes at a constant temperature of 50° C., without subsequent phosphating process.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. It can be seen from the long dotted line in Figure 3 that under the condition that only copper is added, its electrochemical performance is significantly higher than that of pure nickel foam. As can be seen from Figure 5, the as-synthesized Cu-doped monolithic composite has an anode Faradaic efficiency of 97.1%.

Example 4

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut the nickel foam with a blade to 2.5cm×3.5cm and place it vertically in a polytetrafluoroethylene hydrothermal kettle. No copper nitrate, 0.291g of cobalt nitrate, 0.111g of ammonium fluoride and 0.36g of urea were mixed with 40ml of deionized water and stirred uniformly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with water at a constant temperature of 120°C for 6 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain a cobalt-doped overall composite material pre-product. Rinse the pre-product of the cobalt-doped monolithic composite material obtained in step 2 with ethanol, and put it into an oven for drying at a constant temperature of 50° C. for 15 minutes. Cut the 1cm×1.5cm pre-product after hydroheating, put it into the porcelain state and add 0.5g of sodium hypophosphite monohydrate. Put Cizhou into a tube furnace and bake at 300°C for 1h, with argon as the protective gas, and the flow rate is controlled at 20ml/min. After roasting, the cobalt-doped nickel phosphide overall composite composite catalytic material can be obtained.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. It can be seen from Figure 3 that the onset potential of the cobalt-doped nickel phosphide monolithic composite is also very close to the theoretical potential of 1.23V for water splitting.

Example 5

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut the nickel foam with a blade to 2.5cm×3.5cm and place it vertically in a polytetrafluoroethylene hydrothermal kettle. No copper nitrate, 0.291g of cobalt nitrate, 0.111g of ammonium fluoride and 0.36g of urea were mixed with 40ml of deionized water and stirred uniformly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with constant temperature water at 150°C for 4 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain a cobalt-doped monolithic composite material. Rinse the cobalt-doped overall composite material obtained in step 2 with ethanol, put it in an oven and dry it at a constant temperature of 50°C for 15 minutes, without subsequent phosphating process. The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1MKOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. As can be seen from Fig. 5, the as-synthesized Cu-doped monolithic composite has an anodic Faradaic efficiency of 98.2%.

Example 6

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut a 2.5cm×3.5cm nickel foam with a blade and place it vertically in a polytetrafluoroethylene hydrothermal kettle. Weigh 0.121g of copper chloride, 0.291g of cobalt chloride hexahydrate, 0.111g of ammonium bifluoride and 0.05g of potassium hydroxide, mix them with 40ml of deionized water and stir evenly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with water at a constant temperature of 120°C for 4 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain a pre-product of copper and cobalt-doped overall composite material. The obtained copper and cobalt-doped monolithic composite material pre-product was rinsed with ethanol, and dried in an oven at a constant temperature of 50° C. for 15 minutes. Cut the 1cm×2cm pre-product after hydroheating, put it into the porcelain state and add 0.5g sodium phosphate. Put Cizhou into a tube furnace and bake at 250°C for 1h, using argon as a protective gas, and the flow rate of argon is controlled at 20ml/min. After firing, the copper and cobalt doped nickel phosphide overall composite material can be obtained.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. As shown in Figure 4, in the 9 times of 18h constant voltage test, the current density did not drop significantly, showing good electrochemical stability.

Example 7

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut a 2.5cm×3.5cm nickel foam with a blade and place it vertically in a polytetrafluoroethylene hydrothermal kettle. Weigh 0.121g of copper chloride, 0.291g of cobalt chloride hexahydrate, 0.111g of ammonium bifluoride and 0.05g of potassium hydroxide, mix them with 40ml of deionized water and stir evenly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with constant temperature water at 120°C for 5 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain the pre-product of the overall composite material doped with copper and cobalt. The obtained copper and cobalt-doped monolithic composite material pre-product was rinsed with ethanol, and dried in an oven at a constant temperature of 50° C. for 15 minutes. Cut the 1cm×2cm pre-product after hydroheating, put it into the porcelain state and add 0.5g sodium phosphate. Put Cizhou into a tube furnace and bake at 250°C for 1h, using argon as a protective gas, and the flow rate of argon is controlled at 25ml/min. After firing, the copper and cobalt doped nickel phosphide overall composite material can be obtained.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material.

Example 8

Wash the nickel foam with clean water, place it in an oven, and dry it at 60°C for 30 minutes. Cut a 2.5cm×3.5cm nickel foam with a blade and place it vertically in a polytetrafluoroethylene hydrothermal kettle. Weigh 0.121g of copper chloride, 0.291g of cobalt chloride hexahydrate, 0.111g of ammonium bifluoride and 0.05g of potassium hydroxide, mix them with 40ml of deionized water and stir evenly to obtain a raw material solution. Pour the raw material solution into the above-mentioned polytetrafluoroethylene hydrothermal kettle containing foamed nickel, then put the hydrothermal kettle into a constant temperature oven, and heat it with constant temperature water at 120°C for 5 hours. After the hydrothermal reaction, cool naturally in an oven to room temperature and open the hydrothermal kettle to obtain the pre-product of the overall composite material doped with copper and cobalt. The obtained copper and cobalt-doped monolithic composite material pre-product was rinsed with ethanol, and dried in an oven at a constant temperature of 50° C. for 15 minutes. Cut the 1cm×2cm pre-product after hydroheating, put it into the porcelain state and add 0.5g potassium phosphate. Put Cizhou into a tube furnace and bake at 350°C for 1h, using argon as a protective gas, and the flow rate of argon is controlled at 25ml/min. After firing, the copper and cobalt doped nickel phosphide overall composite material can be obtained.

The composite catalytic material obtained above was used as an anode, a commercial Pt sheet electrode was used as a cathode, and a saturated Ag/AgCl was used as a reference electrode. Add 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. As shown in Figure 5, the anode Faraday efficiencies of Examples 1-8 all remain above 98%, which indicates that the synthesized composite catalytic material has good selectivity for HMF oxidation reaction.

Embodiment 9 (this embodiment is blank control)

Wash the nickel foam with water, place it in an oven, and dry it at 60°C for 30 minutes. The dried nickel foam is directly used as the anode, the cathode is a commercial Pt electrode, and the reference electrode is saturated Ag/AgCl. Add 15ml 1M KOH and 95mg HMF into the electrolytic cell, turn on the electrochemical workstation, and test the catalytic performance of the material. It can be seen from accompanying drawing 3 that the short dash line represents the HMF oxidation performance of the nickel foam substrate. Compared with the composite catalysts of Examples 1-5 above, the electrochemical performance of the pure nickel foam substrate is significantly worse than that of the composite catalysts.

The above-mentioned embodiment only expresses the implementation mode of the present invention, but can not therefore be interpreted as the limitation of the scope of the patent of the present invention, it should be pointed out that, for those skilled in the art, under the premise of not departing from the concept of the present invention, Several modifications and improvements can also be made, all of which belong to the protection scope of the present invention.

Claims (10)

1. a preparation method of transition metal-doped nickel phosphide monolithic composite electrocatalytic material, is characterized in that, comprises the following steps: The first step is to prepare a transition metal-doped monolithic composite pre-product 1.1) Dissolving copper salt and cobalt salt in water to obtain a salt solution, then adding ammonium fluoride and urea to the above-mentioned salt solution, stirring evenly to obtain an alkaline raw material solution; 1.2) Put nickel foam into a hydrothermal kettle lined with polytetrafluoroethylene, add the above raw material solution, put the hydrothermal kettle in water for ultrasonic treatment, and perform constant temperature hydrothermal reaction; Naturally cool to room temperature to open the hydrothermal kettle, and obtain a transition metal-doped monolithic composite material pre-product after rinsing; The second step is to prepare transition metal-doped nickel phosphide monolithic composite catalytic materials 2.1) Put the transition metal-doped overall composite pre-product obtained in the first step into an oven for drying; 2.2) Put the dried pre-product into the porcelain state, and add phosphorus salt. The phosphorus salt is placed on the side of the pre-product and close to the pre-product. For every 0.09-0.1g of the pre-stored product, 0-0.5g of the corresponding Phosphate salt; then put the porcelain state in a tube furnace, pass in argon gas as a protective gas, perform phosphating treatment at 250-350°C for 0-1h, rinse and dry it to obtain transition metal-doped Nickel phosphide integral composite catalytic material. 2. the preparation method of the nickel phosphide overall composite catalytic material of a kind of transition metal doping according to claim 1, is characterized in that, in described step 1.1), add 0-0.291g cobalt salt, 0-0.291g cobalt salt, 0- 0.121 g copper salt. 3. the preparation method of the nickel phosphide overall composite catalytic material of a kind of transition metal doping according to claim 1, it is characterized in that, the ammonium fluoride described in described step 1.1) can be replaced by ammonium bifluoride, urea can be Substitute potassium hydroxide. 4. the preparation method of the nickel phosphide integral composite catalytic material of a kind of transition metal doping according to claim 1, is characterized in that, in described step 1.1) cobalt salt is cobalt nitrate hexahydrate, cobalt chloride hexahydrate The one in; the copper salt is one in copper nitrate trihydrate and copper chloride. 5. the preparation method of the nickel phosphide integral composite catalytic material of a kind of transition metal doping according to claim 4, is characterized in that, in described step 1.1), cobalt salt is preferably cobalt nitrate hexahydrate; Described copper salt Copper nitrate trihydrate is preferred; the concentrations of cobalt nitrate hexahydrate, copper nitrate trihydrate, ammonium fluoride, and urea are preferably 0-1mmol/L, 0-0.5mmol/L, 3mmol/L, and 6mmol/L respectively . 6. The preparation method of a transition metal-doped nickel phosphide integral composite catalytic material according to claim 1, characterized in that, in the step 1.2), the constant temperature hydrothermal reaction temperature is 120°C-150°C , the time is 4-6h. 7. the preparation method of the nickel phosphide integral composite catalytic material doped with a kind of transition metal according to claim 1, is characterized in that, in described step 2.2), the flow of argon is controlled at 20-25ml/min, And in order to ensure sufficient phosphating, the flow direction of argon must first pass through the phosphorus salt, and then pass through the pre-product. 8. the preparation method of the nickel phosphide overall composite catalytic material of a kind of transition metal doping according to claim 1, is characterized in that, in described step 2.2), phosphorus salt is sodium phosphate, sodium hypophosphite monohydrate One of substances, potassium phosphate. 9. a transition metal-doped nickel phosphide monolithic composite catalytic material, characterized in that, the transition metal-doped nickel phosphide monolithic composite catalytic material is by the preparation method described in any one of claims 1-8 be made of. 10. the application of a kind of transition metal-doped nickel phosphide monolithic composite catalytic material according to claim 9, characterized in that, the transition metal-doped nickel phosphide monolithic composite catalytic material is applied in hybrid water electrolysis in the hydrogen production reaction.

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